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Recent Articles in Microbiology and Molecular Biology Reviews

Umeno D, Tobias AV, Arnold FH
Diversifying carotenoid biosynthetic pathways by directed evolution.
Microbiol Mol Biol Rev. 2005 Mar;69(1):51-78.
Microorganisms and plants synthesize a diverse array of natural products, many of which have proven indispensable to human health and well-being. Although many thousands of these have been characterized, the space of possible natural products--those that could be made biosynthetically--remains largely unexplored. For decades, this space has largely been the domain of chemists, who have synthesized scores of natural product analogs and have found many with improved or novel functions. New natural products have also been made in recombinant organisms, via engineered biosynthetic pathways. Recently, methods inspired by natural evolution have begun to be applied to the search for new natural products. These methods force pathways to evolve in convenient laboratory organisms, where the products of new pathways can be identified and characterized in high-throughput screening programs. Carotenoid biosynthetic pathways have served as a convenient experimental system with which to demonstrate these ideas. Researchers have mixed, matched, and mutated carotenoid biosynthetic enzymes and screened libraries of these "evolved" pathways for the emergence of new carotenoid products. This has led to dozens of new pathway products not previously known to be made by the assembled enzymes. These new products include whole families of carotenoids built from backbones not found in nature. This review details the strategies and specific methods that have been employed to generate new carotenoid biosynthetic pathways in the laboratory. The potential application of laboratory evolution to other biosynthetic pathways is also discussed. [Abstract/Link to Full Text]

Wolfe AJ
The acetate switch.
Microbiol Mol Biol Rev. 2005 Mar;69(1):12-50.
To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the "acetate switch," occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the "switch" (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl approximately P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl approximately P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl approximately P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl approximately P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to "flip the switch," the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the "acetate switch" as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described. [Abstract/Link to Full Text]

Gottesman ME, Weisberg RA
Little lambda, who made thee?
Microbiol Mol Biol Rev. 2004 Dec;68(4):796-813.
The study of the bacteriophage lambda has been critical to the discipline of molecular biology. It was the source of key discoveries in the mechanisms of, among other processes, gene regulation, recombination, and transcription initiation and termination. We trace here the events surrounding these findings and draw on the recollections of the participants. We show how a particular atmosphere of interactions among creative scientists yielded spectacular insights into how living things work. [Abstract/Link to Full Text]

Ghosh P
Process of protein transport by the type III secretion system.
Microbiol Mol Biol Rev. 2004 Dec;68(4):771-95.
The type III secretion system (TTSS) of gram-negative bacteria is responsible for delivering bacterial proteins, termed effectors, from the bacterial cytosol directly into the interior of host cells. The TTSS is expressed predominantly by pathogenic bacteria and is usually used to introduce deleterious effectors into host cells. While biochemical activities of effectors vary widely, the TTSS apparatus used to deliver these effectors is conserved and shows functional complementarity for secretion and translocation. This review focuses on proteins that constitute the TTSS apparatus and on mechanisms that guide effectors to the TTSS apparatus for transport. The TTSS apparatus includes predicted integral inner membrane proteins that are conserved widely across TTSSs and in the basal body of the bacterial flagellum. It also includes proteins that are specific to the TTSS and contribute to ring-like structures in the inner membrane and includes secretin family members that form ring-like structures in the outer membrane. Most prominently situated on these coaxial, membrane-embedded rings is a needle-like or pilus-like structure that is implicated as a conduit for effector translocation into host cells. A short region of mRNA sequence or protein sequence in effectors acts as a signal sequence, directing proteins for transport through the TTSS. Additionally, a number of effectors require the action of specific TTSS chaperones for efficient and physiologically meaningful translocation into host cells. Numerous models explaining how effectors are transported into host cells have been proposed, but understanding of this process is incomplete and this topic remains an active area of inquiry. [Abstract/Link to Full Text]

Zientz E, Dandekar T, Gross R
Metabolic interdependence of obligate intracellular bacteria and their insect hosts.
Microbiol Mol Biol Rev. 2004 Dec;68(4):745-70.
Mutualistic associations of obligate intracellular bacteria and insects have attracted much interest in the past few years due to the evolutionary consequences for their genome structure. However, much less attention has been paid to the metabolic ramifications for these endosymbiotic microorganisms, which have to compete with but also to adapt to another metabolism--that of the host cell. This review attempts to provide insights into the complex physiological interactions and the evolution of metabolic pathways of several mutualistic bacteria of aphids, ants, and tsetse flies and their insect hosts. [Abstract/Link to Full Text]

Henderson IR, Navarro-Garcia F, Desvaux M, Fernandez RC, Ala'Aldeen D
Type V protein secretion pathway: the autotransporter story.
Microbiol Mol Biol Rev. 2004 Dec;68(4):692-744.
Gram-negative bacteria possess an outer membrane layer which constrains uptake and secretion of solutes and polypeptides. To overcome this barrier, bacteria have developed several systems for protein secretion. The type V secretion pathway encompasses the autotransporter proteins, the two-partner secretion system, and the recently described type Vc or AT-2 family of proteins. Since its discovery in the late 1980s, this family of secreted proteins has expanded continuously, due largely to the advent of the genomic age, to become the largest group of secreted proteins in gram-negative bacteria. Several of these proteins play essential roles in the pathogenesis of bacterial infections and have been characterized in detail, demonstrating a diverse array of function including the ability to condense host cell actin and to modulate apoptosis. However, most of the autotransporter proteins remain to be characterized. In light of new discoveries and controversies in this research field, this review considers the autotransporter secretion process in the context of the more general field of bacterial protein translocation and exoprotein function. [Abstract/Link to Full Text]

Schloss PD, Handelsman J
Status of the microbial census.
Microbiol Mol Biol Rev. 2004 Dec;68(4):686-91.
Over the past 20 years, more than 78,000 16S rRNA gene sequences have been deposited in GenBank and the Ribosomal Database Project, making the 16S rRNA gene the most widely studied gene for reconstructing bacterial phylogeny. While there is a general appreciation that these sequences are largely unique and derived from diverse species of bacteria, there has not been a quantitative attempt to describe the extent of sequencing efforts to date. We constructed rarefaction curves for each bacterial phylum and for the entire bacterial domain to assess the current state of sampling and the relative taxonomic richness of each phylum. This analysis quantifies the general sense among microbiologists that we are a long way from a complete census of the bacteria on Earth. Moreover, the analysis indicates that current sampling strategies might not be the most effective ones to describe novel diversity because there remain numerous phyla that are globally distributed yet poorly sampled. Based on the current level of sampling, it is not possible to estimate the total number of bacterial species on Earth, but the minimum species richness is 35,498. Considering previous global species richness estimates of 10(7) to 10(9), we are certain that this estimate will increase with additional sequencing efforts. The data support previous calls for extensive surveys of multiple chemically disparate environments and of specific phylogenetic groups to advance the census most rapidly. [Abstract/Link to Full Text]

Handelsman J
Metagenomics: application of genomics to uncultured microorganisms.
Microbiol Mol Biol Rev. 2004 Dec;68(4):669-85.
Metagenomics (also referred to as environmental and community genomics) is the genomic analysis of microorganisms by direct extraction and cloning of DNA from an assemblage of microorganisms. The development of metagenomics stemmed from the ineluctable evidence that as-yet-uncultured microorganisms represent the vast majority of organisms in most environments on earth. This evidence was derived from analyses of 16S rRNA gene sequences amplified directly from the environment, an approach that avoided the bias imposed by culturing and led to the discovery of vast new lineages of microbial life. Although the portrait of the microbial world was revolutionized by analysis of 16S rRNA genes, such studies yielded only a phylogenetic description of community membership, providing little insight into the genetics, physiology, and biochemistry of the members. Metagenomics provides a second tier of technical innovation that facilitates study of the physiology and ecology of environmental microorganisms. Novel genes and gene products discovered through metagenomics include the first bacteriorhodopsin of bacterial origin; novel small molecules with antimicrobial activity; and new members of families of known proteins, such as an Na(+)(Li(+))/H(+) antiporter, RecA, DNA polymerase, and antibiotic resistance determinants. Reassembly of multiple genomes has provided insight into energy and nutrient cycling within the community, genome structure, gene function, population genetics and microheterogeneity, and lateral gene transfer among members of an uncultured community. The application of metagenomic sequence information will facilitate the design of better culturing strategies to link genomic analysis with pure culture studies. [Abstract/Link to Full Text]

Dennis PP, Ehrenberg M, Bremer H
Control of rRNA synthesis in Escherichia coli: a systems biology approach.
Microbiol Mol Biol Rev. 2004 Dec;68(4):639-68.
The first part of this review contains an overview of the various contributions and models relating to the control of rRNA synthesis reported over the last 45 years. The second part describes a systems biology approach to identify the factors and effectors that control the interactions between RNA polymerase and rRNA (rrn) promoters of Escherichia coli bacteria during exponential growth in different media. This analysis is based on measurements of absolute rrn promoter activities as transcripts per minute per promoter in bacterial strains either deficient or proficient in the synthesis of the factor Fis and/or the effector ppGpp. These absolute promoter activities are evaluated in terms of rrn promoter strength (V(max)/K(m)) and free RNA polymerase concentrations. Three major conclusions emerge from this evaluation. First, the rrn promoters are not saturated with RNA polymerase. As a consequence, changes in the concentration of free RNA polymerase contribute to changes in rrn promoter activities. Second, rrn P2 promoter strength is not specifically regulated during exponential growth at different rates; its activity changes only when the concentration of free RNA polymerase changes. Third, the effector ppGpp reduces the strength of the rrn P1 promoter both directly and indirectly by reducing synthesis of the stimulating factor Fis. This control of rrn P1 promoter strength forms part of a larger feedback loop that adjusts the synthesis of ribosomes to the availability of amino acids via amino acid-dependent control of ppGpp accumulation. [Abstract/Link to Full Text]

García-Fernández JM, de Marsac NT, Diez J
Streamlined regulation and gene loss as adaptive mechanisms in Prochlorococcus for optimized nitrogen utilization in oligotrophic environments.
Microbiol Mol Biol Rev. 2004 Dec;68(4):630-8.
Prochlorococcus is one of the dominant cyanobacteria and a key primary producer in oligotrophic intertropical oceans. Here we present an overview of the pathways of nitrogen assimilation in Prochlorococcus, which have been significantly modified in these microorganisms for adaptation to the natural limitations of their habitats, leading to the appearance of different ecotypes lacking key enzymes, such as nitrate reductase, nitrite reductase, or urease, and to the simplification of the metabolic regulation systems. The only nitrogen source utilizable by all studied isolates is ammonia, which is incorporated into glutamate by glutamine synthetase. However, this enzyme shows unusual regulatory features, although its structural and kinetic features are unchanged. Similarly, urease activities remain fairly constant under different conditions. The signal transduction protein P(II) is apparently not phosphorylated in Prochlorococcus, despite its conserved amino acid sequence. The genes amt1 and ntcA (coding for an ammonium transporter and a global nitrogen regulator, respectively) show noncorrelated expression in Prochlorococcus under nitrogen stress; furthermore, high rates of organic nitrogen uptake have been observed. All of these unusual features could provide a physiological basis for the predominance of Prochlorococcus over Synechococcus in oligotrophic oceans. [Abstract/Link to Full Text]

Phipps AJ, Premanandan C, Barnewall RE, Lairmore MD
Rabbit and nonhuman primate models of toxin-targeting human anthrax vaccines.
Microbiol Mol Biol Rev. 2004 Dec;68(4):617-29.
The intentional use of Bacillus anthracis, the etiological agent of anthrax, as a bioterrorist weapon in late 2001 made our society acutely aware of the importance of developing, testing, and stockpiling adequate countermeasures against biological attacks. Biodefense vaccines are an important component of our arsenal to be used during a biological attack. However, most of the agents considered significant threats either have been eradicated or rarely infect humans alive today. As such, vaccine efficacy cannot be determined in human clinical trials but must be extrapolated from experimental animal models. This article reviews the efficacy and immunogenicity of human anthrax vaccines in well-defined animal models and the progress toward developing a rugged immunologic correlate of protection. The ongoing evaluation of human anthrax vaccines will be dependent on animal efficacy data in the absence of human efficacy data for licensure by the U.S. Food and Drug Administration. [Abstract/Link to Full Text]

Melo AM, Bandeiras TM, Teixeira M
New insights into type II NAD(P)H:quinone oxidoreductases.
Microbiol Mol Biol Rev. 2004 Dec;68(4):603-16.
Type II NAD(P)H:quinone oxidoreductases (NDH-2) catalyze the two-electron transfer from NAD(P)H to quinones, without any energy-transducing site. NDH-2 accomplish the turnover of NAD(P)H, regenerating the NAD(P)(+) pool, and may contribute to the generation of a membrane potential through complexes III and IV. These enzymes are usually constituted by a nontransmembrane polypeptide chain of approximately 50 kDa, containing a flavin moiety. There are a few compounds that can prevent their activity, but so far no general specific inhibitor has been assigned to these enzymes. However, they have the common feature of being resistant to the complex I classical inhibitors rotenone, capsaicin, and piericidin A. NDH-2 have particular relevance in yeasts like Saccharomyces cerevisiae and in several prokaryotes, whose respiratory chains are devoid of complex I, in which NDH-2 keep the balance and are the main entry point of electrons into the respiratory chains. Our knowledge of these proteins has expanded in the past decade, as a result of contributions at the biochemical level and the sequencing of the genomes from several organisms. The latter showed that most organisms contain genes that potentially encode NDH-2. An overview of this development is presented, with special emphasis on microbial enzymes and on the identification of three subfamilies of NDH-2. [Abstract/Link to Full Text]

Brüssow H, Canchaya C, Hardt WD
Phages and the evolution of bacterial pathogens: from genomic rearrangements to lysogenic conversion.
Microbiol Mol Biol Rev. 2004 Sep;68(3):560-602.
Comparative genomics demonstrated that the chromosomes from bacteria and their viruses (bacteriophages) are coevolving. This process is most evident for bacterial pathogens where the majority contain prophages or phage remnants integrated into the bacterial DNA. Many prophages from bacterial pathogens encode virulence factors. Two situations can be distinguished: Vibrio cholerae, Shiga toxin-producing Escherichia coli, Corynebacterium diphtheriae, and Clostridium botulinum depend on a specific prophage-encoded toxin for causing a specific disease, whereas Staphylococcus aureus, Streptococcus pyogenes, and Salmonella enterica serovar Typhimurium harbor a multitude of prophages and each phage-encoded virulence or fitness factor makes an incremental contribution to the fitness of the lysogen. These prophages behave like "swarms" of related prophages. Prophage diversification seems to be fueled by the frequent transfer of phage material by recombination with superinfecting phages, resident prophages, or occasional acquisition of other mobile DNA elements or bacterial chromosomal genes. Prophages also contribute to the diversification of the bacterial genome architecture. In many cases, they actually represent a large fraction of the strain-specific DNA sequences. In addition, they can serve as anchoring points for genome inversions. The current review presents the available genomics and biological data on prophages from bacterial pathogens in an evolutionary framework. [Abstract/Link to Full Text]

Brehm-Stecher BF, Johnson EA
Single-cell microbiology: tools, technologies, and applications.
Microbiol Mol Biol Rev. 2004 Sep;68(3):538-59.
The field of microbiology has traditionally been concerned with and focused on studies at the population level. Information on how cells respond to their environment, interact with each other, or undergo complex processes such as cellular differentiation or gene expression has been obtained mostly by inference from population-level data. Individual microorganisms, even those in supposedly "clonal" populations, may differ widely from each other in terms of their genetic composition, physiology, biochemistry, or behavior. This genetic and phenotypic heterogeneity has important practical consequences for a number of human interests, including antibiotic or biocide resistance, the productivity and stability of industrial fermentations, the efficacy of food preservatives, and the potential of pathogens to cause disease. New appreciation of the importance of cellular heterogeneity, coupled with recent advances in technology, has driven the development of new tools and techniques for the study of individual microbial cells. Because observations made at the single-cell level are not subject to the "averaging" effects characteristic of bulk-phase, population-level methods, they offer the unique capacity to observe discrete microbiological phenomena unavailable using traditional approaches. As a result, scientists have been able to characterize microorganisms, their activities, and their interactions at unprecedented levels of detail. [Abstract/Link to Full Text]

Gil R, Silva FJ, Peretó J, Moya A
Determination of the core of a minimal bacterial gene set.
Microbiol Mol Biol Rev. 2004 Sep;68(3):518-37.
The availability of a large number of complete genome sequences raises the question of how many genes are essential for cellular life. Trying to reconstruct the core of the protein-coding gene set for a hypothetical minimal bacterial cell, we have performed a computational comparative analysis of eight bacterial genomes. Six of the analyzed genomes are very small due to a dramatic genome size reduction process, while the other two, corresponding to free-living relatives, are larger. The available data from several systematic experimental approaches to define all the essential genes in some completely sequenced bacterial genomes were also considered, and a reconstruction of a minimal metabolic machinery necessary to sustain life was carried out. The proposed minimal genome contains 206 protein-coding genes with all the genetic information necessary for self-maintenance and reproduction in the presence of a full complement of essential nutrients and in the absence of environmental stress. The main features of such a minimal gene set, as well as the metabolic functions that must be present in the hypothetical minimal cell, are discussed. [Abstract/Link to Full Text]

Schweizer E, Hofmann J
Microbial type I fatty acid synthases (FAS): major players in a network of cellular FAS systems.
Microbiol Mol Biol Rev. 2004 Sep;68(3):501-17.
The present review focuses on microbial type I fatty acid synthases (FASs), demonstrating their structural and functional diversity. Depending on their origin and biochemical function, multifunctional type I FAS proteins form dimers or hexamers with characteristic organization of their catalytic domains. A single polypeptide may contain one or more sets of the eight FAS component functions. Alternatively, these functions may split up into two different and mutually complementing subunits. Targeted inactivation of the individual yeast FAS acylation sites allowed us to define their roles during the overall catalytic process. In particular, their pronounced negative cooperativity is presumed to coordinate the FAS initiation and chain elongation reactions. Expression of the unlinked genes, FAS1 and FAS2, is in part constitutive and in part subject to repression by the phospholipid precursors inositol and choline. The interplay of the involved regulatory proteins, Rap1, Reb1, Abf1, Ino2/Ino4, Opi1, Sin3 and TFIIB, has been elucidated in considerable detail. Balanced levels of subunits alpha and beta are ensured by an autoregulatory effect of FAS1 on FAS2 expression and by posttranslational degradation of excess FAS subunits. The functional specificity of type I FAS multienzymes usually requires the presence of multiple FAS systems within the same cell. De novo synthesis of long-chain fatty acids, mitochondrial fatty acid synthesis, acylation of certain secondary metabolites and coenzymes, fatty acid elongation, and the vast diversity of mycobacterial lipids each result from specific FAS activities. The microcompartmentalization of FAS activities in type I multienzymes may thus allow for both the controlled and concerted action of multiple FAS systems within the same cell. [Abstract/Link to Full Text]

Tropel D, van der Meer JR
Bacterial transcriptional regulators for degradation pathways of aromatic compounds.
Microbiol Mol Biol Rev. 2004 Sep;68(3):474-500.
Human activities have resulted in the release and introduction into the environment of a plethora of aromatic chemicals. The interest in discovering how bacteria are dealing with hazardous environmental pollutants has driven a large research community and has resulted in important biochemical, genetic, and physiological knowledge about the degradation capacities of microorganisms and their application in bioremediation, green chemistry, or production of pharmacy synthons. In addition, regulation of catabolic pathway expression has attracted the interest of numerous different groups, and several catabolic pathway regulators have been exemplary for understanding transcription control mechanisms. More recently, information about regulatory systems has been used to construct whole-cell living bioreporters that are used to measure the quality of the aqueous, soil, and air environment. The topic of biodegradation is relatively coherent, and this review presents a coherent overview of the regulatory systems involved in the transcriptional control of catabolic pathways. This review summarizes the different regulatory systems involved in biodegradation pathways of aromatic compounds linking them to other known protein families. Specific attention has been paid to describing the genetic organization of the regulatory genes, promoters, and target operon(s) and to discussing present knowledge about signaling molecules, DNA binding properties, and operator characteristics, and evidence from regulatory mutants. For each regulator family, this information is combined with recently obtained protein structural information to arrive at a possible mechanism of transcription activation. This demonstrates the diversity of control mechanisms existing in catabolic pathways. [Abstract/Link to Full Text]

Roberts GP, Youn H, Kerby RL
CO-sensing mechanisms.
Microbiol Mol Biol Rev. 2004 Sep;68(3):453-73.
Carbon monoxide (CO) has long been known to have dramatic physiological effects on organisms ranging from bacteria to humans, but recently there have a number of suggestions that organisms might have specific sensors for CO. This article reviews the current evidence for a variety of proteins with demonstrated or potential CO-sensing ability. Particular emphasis is placed on the molecular description of CooA, a heme-containing CO sensor from Rhodospirillum rubrum, since its biological role as a CO sensor is clear and we have substantial insight into the basis of its sensing ability. [Abstract/Link to Full Text]

Wang Q, Carmichael GG
Effects of length and location on the cellular response to double-stranded RNA.
Microbiol Mol Biol Rev. 2004 Sep;68(3):432-52.
Since double-stranded RNA (dsRNA) has not until recently generally been thought to be deliberately expressed in cells, it has commonly been assumed that the major source of cellular dsRNA is viral infections. In this view, the cellular responses to dsRNA would be natural and perhaps ancient antiviral responses. While the cell may certainly react to some dsRNAs as an antiviral response, this does not represent the only response or even, perhaps, the major one. A number of recent observations have pointed to the possibility that dsRNA molecules are not seen only as evidence of viral infection or recognized for degradation because they cannot be translated. In some instances they may also play important roles in normal cell growth and function. The purpose of this review is to outline our current understanding of the fate of dsRNA in cells, with a focus on the apparent fact that their fates and functions appear to depend critically not only on where in the cell dsRNA molecules are found, but also on how long they are and perhaps on how abundant they are. [Abstract/Link to Full Text]

Thompson FL, Iida T, Swings J
Biodiversity of vibrios.
Microbiol Mol Biol Rev. 2004 Sep;68(3):403-31, table of contents.
Vibrios are ubiquitous and abundant in the aquatic environment. A high abundance of vibrios is also detected in tissues and/or organs of various marine algae and animals, e.g., abalones, bivalves, corals, fish, shrimp, sponges, squid, and zooplankton. Vibrios harbour a wealth of diverse genomes as revealed by different genomic techniques including amplified fragment length polymorphism, multilocus sequence typing, repetetive extragenic palindrome PCR, ribotyping, and whole-genome sequencing. The 74 species of this group are distributed among four different families, i.e., Enterovibrionaceae, Photobacteriaceae, Salinivibrionaceae, and Vibrionaceae. Two new genera, i.e., Enterovibrio norvegicus and Grimontia hollisae, and 20 novel species, i.e., Enterovibrio coralii, Photobacterium eurosenbergii, V. brasiliensis, V. chagasii, V. coralliillyticus, V. crassostreae, V. fortis, V. gallicus, V. hepatarius, V. hispanicus, V. kanaloaei, V. neonatus, V. neptunius, V. pomeroyi, V. pacinii, V. rotiferianus, V. superstes, V. tasmaniensis, V. ezurae, and V. xuii, have been described in the last few years. Comparative genome analyses have already revealed a variety of genomic events, including mutations, chromosomal rearrangements, loss of genes by decay or deletion, and gene acquisitions through duplication or horizontal transfer (e.g., in the acquisition of bacteriophages, pathogenicity islands, and super-integrons), that are probably important driving forces in the evolution and speciation of vibrios. Whole-genome sequencing and comparative genomics through the application of, e.g., microarrays will facilitate the investigation of the gene repertoire at the species level. Based on such new genomic information, the taxonomy and the species concept for vibrios will be reviewed in the next years. [Abstract/Link to Full Text]

Barth H, Aktories K, Popoff MR, Stiles BG
Binary bacterial toxins: biochemistry, biology, and applications of common Clostridium and Bacillus proteins.
Microbiol Mol Biol Rev. 2004 Sep;68(3):373-402, table of contents.
Certain pathogenic species of Bacillus and Clostridium have developed unique methods for intoxicating cells that employ the classic enzymatic "A-B" paradigm for protein toxins. The binary toxins produced by B. anthracis, B. cereus, C. botulinum, C. difficile, C. perfringens, and C. spiroforme consist of components not physically associated in solution that are linked to various diseases in humans, animals, or insects. The "B" components are synthesized as precursors that are subsequently activated by serine-type proteases on the targeted cell surface and/or in solution. Following release of a 20-kDa N-terminal peptide, the activated "B" components form homoheptameric rings that subsequently dock with an "A" component(s) on the cell surface. By following an acidified endosomal route and translocation into the cytosol, "A" molecules disable a cell (and host organism) via disruption of the actin cytoskeleton, increasing intracellular levels of cyclic AMP, or inactivation of signaling pathways linked to mitogen-activated protein kinase kinases. Recently, B. anthracis has gleaned much notoriety as a biowarfare/bioterrorism agent, and of primary interest has been the edema and lethal toxins, their role in anthrax, as well as the development of efficacious vaccines and therapeutics targeting these virulence factors and ultimately B. anthracis. This review comprehensively surveys the literature and discusses the similarities, as well as distinct differences, between each Clostridium and Bacillus binary toxin in terms of their biochemistry, biology, genetics, structure, and applications in science and medicine. The information may foster future studies that aid novel vaccine and drug development, as well as a better understanding of a conserved intoxication process utilized by various gram-positive, spore-forming bacteria. [Abstract/Link to Full Text]

Longworth MS, Laimins LA
Pathogenesis of human papillomaviruses in differentiating epithelia.
Microbiol Mol Biol Rev. 2004 Jun;68(2):362-72.
Human papillomaviruses (HPV) are the etiological agents of cervical and other anogenital malignancies. Over 100 different types of HPVs have been identified to date, and all target epithelial tissues for infection. One-third of HPV types specifically infect the genital tract, and a subset of these are the causative agents of anogenital cancers. Other HPV types that infect the genital tract induce benign hyperproliferative lesions or genital warts. The productive life cycle of HPVs is linked to epithelial differentiation. Papillomaviruses are thought to infect cells in the basal layer of stratified epithelia and establish their genomes as multicopy nuclear episomes. In these cells, viral DNA is replicated along with cellular chromosomes. Following cell division, one of the daughter cells migrates away from the basal layer and undergoes differentiation. In highly differentiated suprabasal cells, vegetative viral replication and late-gene expression are activated, resulting in the generation of progeny virions. Since virion production is restricted to differentiated cells, infected basal cells can persist for up to several decades or until the immune system clears the infection. The E6 and E7 genes encode viral oncoproteins that target Rb and p53, respectively. During the viral life cycle, these proteins facilitate stable maintenance of episomes and stimulate differentiated cells to reenter the S phase. The E1 and E2 proteins act as origin recognition factors as well as regulators of early viral transcription. The functions of the E5 and E1--E4 proteins are still largely unknown, but these proteins have been implicated in modulating late viral functions. The L1 and L2 proteins form icosahedral capsids for progeny virion generation. The characterization of the cellular targets of these viral proteins and the mechanisms regulating the differentiation-dependent viral life cycle remain active areas for the study of these important human pathogens. [Abstract/Link to Full Text]

Nickerson CA, Ott CM, Wilson JW, Ramamurthy R, Pierson DL
Microbial responses to microgravity and other low-shear environments.
Microbiol Mol Biol Rev. 2004 Jun;68(2):345-61.
Microbial adaptation to environmental stimuli is essential for survival. While several of these stimuli have been studied in detail, recent studies have demonstrated an important role for a novel environmental parameter in which microgravity and the low fluid shear dynamics associated with microgravity globally regulate microbial gene expression, physiology, and pathogenesis. In addition to analyzing fundamental questions about microbial responses to spaceflight, these studies have demonstrated important applications for microbial responses to a ground-based, low-shear stress environment similar to that encountered during spaceflight. Moreover, the low-shear growth environment sensed by microbes during microgravity of spaceflight and during ground-based microgravity analogue culture is relevant to those encountered during their natural life cycles on Earth. While no mechanism has been clearly defined to explain how the mechanical force of fluid shear transmits intracellular signals to microbial cells at the molecular level, the fact that cross talk exists between microbial signal transduction systems holds intriguing possibilities that future studies might reveal common mechanotransduction themes between these systems and those used to sense and respond to low-shear stress and changes in gravitation forces. The study of microbial mechanotransduction may identify common conserved mechanisms used by cells to perceive changes in mechanical and/or physical forces, and it has the potential to provide valuable insight for understanding mechanosensing mechanisms in higher organisms. This review summarizes recent and future research trends aimed at understanding the dynamic effects of changes in the mechanical forces that occur in microgravity and other low-shear environments on a wide variety of important microbial parameters. [Abstract/Link to Full Text]

Roux PP, Blenis J
ERK and p38 MAPK-activated protein kinases: a family of protein kinases with diverse biological functions.
Microbiol Mol Biol Rev. 2004 Jun;68(2):320-44.
Conserved signaling pathways that activate the mitogen-activated protein kinases (MAPKs) are involved in relaying extracellular stimulations to intracellular responses. The MAPKs coordinately regulate cell proliferation, differentiation, motility, and survival, which are functions also known to be mediated by members of a growing family of MAPK-activated protein kinases (MKs; formerly known as MAPKAP kinases). The MKs are related serine/threonine kinases that respond to mitogenic and stress stimuli through proline-directed phosphorylation and activation of the kinase domain by extracellular signal-regulated kinases 1 and 2 and p38 MAPKs. There are currently 11 vertebrate MKs in five subfamilies based on primary sequence homology: the ribosomal S6 kinases, the mitogen- and stress-activated kinases, the MAPK-interacting kinases, MAPK-activated protein kinases 2 and 3, and MK5. In the last 5 years, several MK substrates have been identified, which has helped tremendously to identify the biological role of the members of this family. Together with data from the study of MK-knockout mice, the identities of the MK substrates indicate that they play important roles in diverse biological processes, including mRNA translation, cell proliferation and survival, and the nuclear genomic response to mitogens and cellular stresses. In this article, we review the existing data on the MKs and discuss their physiological functions based on recent discoveries. [Abstract/Link to Full Text]

Szurmant H, Ordal GW
Diversity in chemotaxis mechanisms among the bacteria and archaea.
Microbiol Mol Biol Rev. 2004 Jun;68(2):301-19.
The study of chemotaxis describes the cellular processes that control the movement of organisms toward favorable environments. In bacteria and archaea, motility is controlled by a two-component system involving a histidine kinase that senses the environment and a response regulator, a very common type of signal transduction in prokaryotes. Most insights into the processes involved have come from studies of Escherichia coli over the last three decades. However, in the last 10 years, with the sequencing of many prokaryotic genomes, it has become clear that E. coli represents a streamlined example of bacterial chemotaxis. While general features of excitation remain conserved among bacteria and archaea, specific features, such as adaptational processes and hydrolysis of the intracellular signal CheY-P, are quite diverse. The Bacillus subtilis chemotaxis system is considerably more complex and appears to be similar to the one that existed when the bacteria and archaea separated during evolution, so that understanding this mechanism should provide insight into the variety of mechanisms used today by the broad sweep of chemotactic bacteria and archaea. However, processes even beyond those used in E. coli and B. subtilis have been discovered in other organisms. This review emphasizes those used by B. subtilis and these other organisms but also gives an account of the mechanism in E. coli. [Abstract/Link to Full Text]

Gage DJ
Infection and invasion of roots by symbiotic, nitrogen-fixing rhizobia during nodulation of temperate legumes.
Microbiol Mol Biol Rev. 2004 Jun;68(2):280-300.
Bacteria belonging to the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Azorhizobium (collectively referred to as rhizobia) grow in the soil as free-living organisms but can also live as nitrogen-fixing symbionts inside root nodule cells of legume plants. The interactions between several rhizobial species and their host plants have become models for this type of nitrogen-fixing symbiosis. Temperate legumes such as alfalfa, pea, and vetch form indeterminate nodules that arise from root inner and middle cortical cells and grow out from the root via a persistent meristem. During the formation of functional indeterminate nodules, symbiotic bacteria must gain access to the interior of the host root. To get from the outside to the inside, rhizobia grow and divide in tubules called infection threads, which are composite structures derived from the two symbiotic partners. This review focuses on symbiotic infection and invasion during the formation of indeterminate nodules. It summarizes root hair growth, how root hair growth is influenced by rhizobial signaling molecules, infection of root hairs, infection thread extension down root hairs, infection thread growth into root tissue, and the plant and bacterial contributions necessary for infection thread formation and growth. The review also summarizes recent advances concerning the growth dynamics of rhizobial populations in infection threads. [Abstract/Link to Full Text]

Elsen S, Swem LR, Swem DL, Bauer CE
RegB/RegA, a highly conserved redox-responding global two-component regulatory system.
Microbiol Mol Biol Rev. 2004 Jun;68(2):263-79.
The Reg regulon from Rhodobacter capsulatus and Rhodobacter sphaeroides encodes proteins involved in numerous energy-generating and energy-utilizing processes such as photosynthesis, carbon fixation, nitrogen fixation, hydrogen utilization, aerobic and anaerobic respiration, denitrification, electron transport, and aerotaxis. The redox signal that is detected by the membrane-bound sensor kinase, RegB, appears to originate from the aerobic respiratory chain, given that mutations in cytochrome c oxidase result in constitutive RegB autophosphorylation. Regulation of RegB autophosphorylation also involves a redox-active cysteine that is present in the cytosolic region of RegB. Both phosphorylated and unphosphorylated forms of the cognate response regulator RegA are capable of activating or repressing a variety of genes in the regulon. Highly conserved homologues of RegB and RegA have been found in a wide number of photosynthetic and nonphotosynthetic bacteria, with evidence suggesting that RegB/RegA plays a fundamental role in the transcription of redox-regulated genes in many bacterial species. [Abstract/Link to Full Text]

Hilbert DW, Piggot PJ
Compartmentalization of gene expression during Bacillus subtilis spore formation.
Microbiol Mol Biol Rev. 2004 Jun;68(2):234-62.
Gene expression in members of the family Bacillaceae becomes compartmentalized after the distinctive, asymmetrically located sporulation division. It involves complete compartmentalization of the activities of sporulation-specific sigma factors, sigma(F) in the prespore and then sigma(E) in the mother cell, and then later, following engulfment, sigma(G) in the prespore and then sigma(K) in the mother cell. The coupling of the activation of sigma(F) to septation and sigma(G) to engulfment is clear; the mechanisms are not. The sigma factors provide the bare framework of compartment-specific gene expression. Within each sigma regulon are several temporal classes of genes, and for key regulators, timing is critical. There are also complex intercompartmental regulatory signals. The determinants for sigma(F) regulation are assembled before septation, but activation follows septation. Reversal of the anti-sigma(F) activity of SpoIIAB is critical. Only the origin-proximal 30% of a chromosome is present in the prespore when first formed; it takes approximately 15 min for the rest to be transferred. This transient genetic asymmetry is important for prespore-specific sigma(F) activation. Activation of sigma(E) requires sigma(F) activity and occurs by cleavage of a prosequence. It must occur rapidly to prevent the formation of a second septum. sigma(G) is formed only in the prespore. SpoIIAB can block sigma(G) activity, but SpoIIAB control does not explain why sigma(G) is activated only after engulfment. There is mother cell-specific excision of an insertion element in sigK and sigma(E)-directed transcription of sigK, which encodes pro-sigma(K). Activation requires removal of the prosequence following a sigma(G)-directed signal from the prespore. [Abstract/Link to Full Text]

Tjalsma H, Antelmann H, Jongbloed JD, Braun PG, Darmon E, Dorenbos R, Dubois JY, Westers H, Zanen G, Quax WJ, Kuipers OP, Bron S, Hecker M, van Dijl JM
Proteomics of protein secretion by Bacillus subtilis: separating the "secrets" of the secretome.
Microbiol Mol Biol Rev. 2004 Jun;68(2):207-33.
Secretory proteins perform a variety of important "remote-control" functions for bacterial survival in the environment. The availability of complete genome sequences has allowed us to make predictions about the composition of bacterial machinery for protein secretion as well as the extracellular complement of bacterial proteomes. Recently, the power of proteomics was successfully employed to evaluate genome-based models of these so-called secretomes. Progress in this field is well illustrated by the proteomic analysis of protein secretion by the gram-positive bacterium Bacillus subtilis, for which approximately 90 extracellular proteins were identified. Analysis of these proteins disclosed various "secrets of the secretome," such as the residence of cytoplasmic and predicted cell envelope proteins in the extracellular proteome. This showed that genome-based predictions reflect only approximately 50% of the actual composition of the extracellular proteome of B. subtilis. Importantly, proteomics allowed the first verification of the impact of individual secretion machinery components on the total flow of proteins from the cytoplasm to the extracellular environment. In conclusion, proteomics has yielded a variety of novel leads for the analysis of protein traffic in B. subtilis and other gram-positive bacteria. Ultimately, such leads will serve to increase our understanding of virulence factor biogenesis in gram-positive pathogens, which is likely to be of high medical relevance. [Abstract/Link to Full Text]

Gray JV, Petsko GA, Johnston GC, Ringe D, Singer RA, Werner-Washburne M
"Sleeping beauty": quiescence in Saccharomyces cerevisiae.
Microbiol Mol Biol Rev. 2004 Jun;68(2):187-206.
The cells of organisms as diverse as bacteria and humans can enter stable, nonproliferating quiescent states. Quiescent cells of eukaryotic and prokaryotic microorganisms can survive for long periods without nutrients. This alternative state of cells is still poorly understood, yet much benefit is to be gained by understanding it both scientifically and with reference to human health. Here, we review our knowledge of one "model" quiescent cell population, in cultures of yeast grown to stationary phase in rich media. We outline the importance of understanding quiescence, summarize the properties of quiescent yeast cells, and clarify some definitions of the state. We propose that the processes by which a cell enters into, maintains viability in, and exits from quiescence are best viewed as an environmentally triggered cycle: the cell quiescence cycle. We synthesize what is known about the mechanisms by which yeast cells enter into quiescence, including the possible roles of the protein kinase A, TOR, protein kinase C, and Snf1p pathways. We also discuss selected mechanisms by which quiescent cells maintain viability, including metabolism, protein modification, and redox homeostasis. Finally, we outline what is known about the process by which cells exit from quiescence when nutrients again become available. [Abstract/Link to Full Text]


Recent Articles in Applied and Environmental Microbiology

Coutard F, Lozach S, Pommepuy M, Hervio-Heath D
Real-time reverse transcription-PCR for transcriptional expression analysis of virulence and housekeeping genes in viable but nonculturable Vibrio parahaemolyticus after recovery of culturability.
Appl Environ Microbiol. 2007 Aug;73(16):5183-9.
A real-time reverse transcription-PCR method was developed to determine whether the recovery of culturability of viable but nonculturable (VBNC) Vibrio parahaemolyticus induced the expression of virulence genes coding for the thermostable direct hemolysin and for type III secretion system 2 (TTSS2). The culturability of clinical strain Vp5 of V. parahaemolyticus in artificial seawater at 4 degrees C was monitored, and the VBNC state was obtained. One day after entry into the VBNC state, temperature upshifts to 20 and 37 degrees C allowed the recovery of culturability. Standard curves for the relative quantification of expression of the housekeeping genes rpoS, pvsA, fur, and pvuA; the tdh2 gene; and the TTSS2 genes (VPA1354, VPA1346, and VPA1342) were established. The levels of expression of the pvsA and pvuA genes were stable and were used to normalize the levels of expression of the other genes. No transcriptional induction of the selected virulence genes under the temperature conditions used to recover the culturability of the VBNC bacteria was observed. The study results demonstrate that the recovery of culturability of VBNC cells of pathogenic V. parahaemolyticus is restricted to regrowth, without correlation with the induction of virulence gene expression. Disease induction would depend mainly on host-pathogen interactions that allow the expression of the virulence genes. This is the first time that the use of mRNA to detect viable cells was evaluated by computing the half-lives of multiple mRNA species under conditions inducing the VBNC state. [Abstract/Link to Full Text]

Harrison JJ, Ceri H, Yerly J, Rabiei M, Hu Y, Martinuzzi R, Turner RJ
Metal ions may suppress or enhance cellular differentiation in Candida albicans and Candida tropicalis biofilms.
Appl Environ Microbiol. 2007 Aug;73(15):4940-9.
Candida albicans and Candida tropicalis are polymorphic fungi that develop antimicrobial-resistant biofilm communities that are characterized by multiple cell morphotypes. This study investigated cell type interconversion and drug and metal resistance as well as community organization in biofilms of these microorganisms that were exposed to metal ions. To study this, Candida biofilms were grown either in microtiter plates containing gradient arrays of metal ions or in the Calgary Biofilm Device for high-throughput susceptibility testing. Biofilm formation and antifungal resistance were evaluated by viable cell counts, tetrazolium salt reduction, light microscopy, and confocal laser scanning microscopy in conjunction with three-dimensional visualization. We discovered that subinhibitory concentrations of certain metal ions (CrO(4)(2-), Co(2+), Cu(2+), Ag(+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), AsO(2)(-), and SeO(3)(2-)) caused changes in biofilm structure by blocking or eliciting the transition between yeast and hyphal cell types. Four distinct biofilm community structure types were discerned from these data, which were designated "domed," "layer cake," "flat," and "mycelial." This study suggests that Candida biofilm populations may respond to metal ions to form cell-cell and solid-surface-attached assemblages with distinct patterns of cellular differentiation. [Abstract/Link to Full Text]

de María N, Guevara A, Serra MT, García-Luque I, González-Sama A, García de Lacoba M, de Felipe MR, Fernández-Pascual M
Putative porin of Bradyrhizobium sp. (Lupinus) bacteroids induced by glyphosate.
Appl Environ Microbiol. 2007 Aug;73(16):5075-82.
Application of glyphosate (N-[phosphonomethyl] glycine) to Bradyrhizobium sp. (Lupinus)-nodulated lupin plants caused modifications in the protein pattern of bacteroids. The most significant change was the presence of a 44-kDa polypeptide in bacteroids from plants treated with the higher doses of glyphosate employed (5 and 10 mM). The polypeptide has been characterized by the amino acid sequencing of its N terminus and the isolation and nucleic acid sequencing of its encoding gene. It is putatively encoded by a single gene, and the protein has been identified as a putative porin. Protein modeling revealed the existence of several domains sharing similarity to different porins, such as a transmembrane beta-barrel. The protein has been designated BLpp, for Bradyrhizobium sp. (Lupinus) putative porin, and would be the first porin described in Bradyrhizobium sp. (Lupinus). In addition, a putative conserved domain of porins has been identified which consists of 87 amino acids, located in the BLpp sequence 30 amino acids downstream of the N-terminal region. In bacteroids, mRNA of the BLpp gene shows a basal constitutive expression that increases under glyphosate treatment, and the expression of the gene is seemingly regulated at the transcriptional level. By contrast, in free-living bacteria glyphosate treatment leads to an inhibition of BLpp mRNA accumulation, indicating a different effect of glyphosate on BLpp gene expression in bacteroids and free-living bacteria. The possible role of BLpp in a metabolite interchange between Bradyrhizobium and lupin is discussed. [Abstract/Link to Full Text]

Spain AM, Peacock AD, Istok JD, Elshahed MS, Najar FZ, Roe BA, White DC, Krumholz LR
Identification and isolation of a Castellaniella species important during biostimulation of an acidic nitrate- and uranium-contaminated aquifer.
Appl Environ Microbiol. 2007 Aug;73(15):4892-904.
Immobilization of uranium in groundwater can be achieved through microbial reduction of U(VI) to U(IV) upon electron donor addition. Microbial community structure was analyzed in ethanol-biostimulated and control sediments from a high-nitrate (>130 mM), low-pH, uranium-contaminated site in Oak Ridge, TN. Analysis of small subunit (SSU) rRNA gene clone libraries and polar lipid fatty acids from sediments revealed that biostimulation resulted in a general decrease in bacterial diversity. Specifically, biostimulation resulted in an increase in the proportion of Betaproteobacteria (10% of total clones in the control sediment versus 50 and 79% in biostimulated sediments) and a decrease in the proportion of Gammaproteobacteria and Acidobacteria. Clone libraries derived from dissimilatory nitrite reductase genes (nirK and nirS) were also dominated by clones related to Betaproteobacteria (98% and 85% of total nirK and nirS clones, respectively). Within the nirK libraries, one clone sequence made up 59 and 76% of sequences from biostimulated sediments but only made up 10% of the control nirK library. Phylogenetic analysis of SSU rRNA and nirK gene sequences from denitrifying pure cultures isolated from the site indicate that all belong to a Castellaniella species; nearly identical sequences also constituted the majority of biostimulated SSU rRNA and nirK clone libraries. Thus, by combining culture-independent with culture-dependent techniques, we were able to link SSU rRNA clone library information with nirK sequence data and conclude that a potentially novel Castellaniella species is important for in situ nitrate removal at this site. [Abstract/Link to Full Text]

Kamgang-Youbi G, Herry JM, Bellon-Fontaine MN, Brisset JL, Doubla A, Naïtali M
Evidence of temporal postdischarge decontamination of bacteria by gliding electric discharges: application to Hafnia alvei.
Appl Environ Microbiol. 2007 Aug;73(15):4791-6.
This study aimed to characterize the bacterium-destroying properties of a gliding arc plasma device during electric discharges and also under temporal postdischarge conditions (i.e., when the discharge was switched off). This phenomenon was reported for the first time in the literature in the case of the plasma destruction of microorganisms. When cells of a model bacterium, Hafnia alvei, were exposed to electric discharges, followed or not followed by temporal postdischarges, the survival curves exhibited a shoulder and then log-linear decay. These destruction kinetics were modeled using GinaFiT, a freeware tool to assess microbial survival curves, and adjustment parameters were determined. The efficiency of postdischarge treatments was clearly affected by the discharge time (t*); both the shoulder length and the inactivation rate k(max) were linearly modified as a function of t*. Nevertheless, all conditions tested (t* ranging from 2 to 5 min) made it possible to achieve an abatement of at least 7 decimal logarithm units. Postdischarge treatment was also efficient against bacteria not subjected to direct discharge, and the disinfecting properties of "plasma-activated water" were dependent on the treatment time for the solution. Water treated with plasma for 2 min achieved a 3.7-decimal-logarithm-unit reduction in 20 min after application to cells, and abatement greater than 7 decimal logarithm units resulted from the same contact time with water activated with plasma for 10 min. These disinfecting properties were maintained during storage of activated water for 30 min. After that, they declined as the storage time increased. [Abstract/Link to Full Text]

Kolvenbach B, Schlaich N, Raoui Z, Prell J, Zühlke S, Schäffer A, Guengerich FP, Corvini PF
Degradation pathway of bisphenol A: does ipso substitution apply to phenols containing a quaternary alpha-carbon structure in the para position?
Appl Environ Microbiol. 2007 Aug;73(15):4776-84.
The degradation of bisphenol A and nonylphenol involves the unusual rearrangement of stable carbon-carbon bonds. Some nonylphenol isomers and bisphenol A possess a quaternary alpha-carbon atom as a common structural feature. The degradation of nonylphenol in Sphingomonas sp. strain TTNP3 occurs via a type II ipso substitution with the presence of a quaternary alpha-carbon as a prerequisite. We report here a new degradation pathway of bisphenol A. Consequent to the hydroxylation at position C-4, according to a type II ipso substitution mechanism, the C-C bond between the phenolic moiety and the isopropyl group of bisphenol A is broken. Besides the formation of hydroquinone and 4-(2-hydroxypropan-2-yl)phenol as the main metabolites, further compounds resulting from molecular rearrangements consistent with a carbocationic intermediate were identified. Assays with resting cells or cell extracts of Sphingomonas sp. strain TTNP3 under an (18)O(2) atmosphere were performed. One atom of (18)O(2) was present in hydroquinone, resulting from the monooxygenation of bisphenol A and nonylphenol. The monooxygenase activity was dependent on both NADPH and flavin adenine dinucleotide. Various cytochrome P450 inhibitors had identical inhibition effects on the conversion of both xenobiotics. Using a mutant of Sphingomonas sp. strain TTNP3, which is defective for growth on nonylphenol, we demonstrated that the reaction is catalyzed by the same enzymatic system. In conclusion, the degradation of bisphenol A and nonylphenol is initiated by the same monooxygenase, which may also lead to ipso substitution in other xenobiotics containing phenol with a quaternary alpha-carbon. [Abstract/Link to Full Text]

Schleheck D, Knepper TP, Eichhorn P, Cook AM
Parvibaculum lavamentivorans DS-1T degrades centrally substituted congeners of commercial linear alkylbenzenesulfonate to sulfophenyl carboxylates and sulfophenyl dicarboxylates.
Appl Environ Microbiol. 2007 Aug;73(15):4725-32.
Commercial linear alkylbenzenesulfonate (LAS) contains 20 congeners of linear alkanes (C(10) to C(13)) substituted subterminally with the 4-sulfophenyl moiety in any position from lateral to central. Parvibaculum lavamentivorans DS-1(T) degrades each of eight laterally substituted congeners [e.g., 2-(4-sulfophenyl)decane (2-C10-LAS); herein, compounds are named systematically by chain length (e.g., C(10)) and by the position of the substituent on the chain (e.g., position 2)] to a major sulfophenyl carboxylate [SPC; here 3-(4-sulfophenyl)butyrate (3-C4-SPC)] and two minor products, namely, the alpha,beta-unsaturated SPC (SPC-2H, here 3-C4-SPC-2H) and the SPC+2C (here 5-C6-SPC) species (D. Schleheck, T. P. Knepper, K. Fischer, and A. M. Cook, Appl. Environ. Microbiol. 70:4053-4063). The degradation of centrally substituted congeners by strain DS-1 was examined in this work. 5-C10-LAS yielded not only the predicted 4-C8-SPC, 4-C8-SPC-2H, and 6-C10-SPC (about 70% of products) but also sulfophenyl dicarboxylates (SPdC), i.e., C6-, C8-, and C10-SPdC. These were identified by electrospray ionization-mass spectrometry (ESI-MS) after separation by high-pressure liquid chromatography (HPLC). ESI ion-trap MS and ESI-time of flight-MS were used to confirm the identities of key intermediates. Different mixtures of congeners obtained by separation of commercial LAS by HPLC were degraded, and the degradative products were compared. If a congener carried the sulfophenyl substituent on the 5, 6, or 7 position, SPdCs were formed as well as SPC, SPC-2H, and SPC+2C, whereas the substituent on the 2, 3, or 4 position yielded only SPC, SPC-2H, and SPC+2C. Some 50 products were generated from the 20 LAS congeners: 11 major SPCs, each with an SPC-2H and an SPC+2C (i.e., 33 SPC and SPC-2H species), and about 17 SPdC species. A large array of compounds, many in low quantities, is thus generated by P. lavamentivorans DS-1 during the degradation of commercial LAS. [Abstract/Link to Full Text]

Beutin L, Miko A, Krause G, Pries K, Haby S, Steege K, Albrecht N
Identification of human-pathogenic strains of Shiga toxin-producing Escherichia coli from food by a combination of serotyping and molecular typing of Shiga toxin genes.
Appl Environ Microbiol. 2007 Aug;73(15):4769-75.
We examined 219 Shiga toxin-producing Escherichia coli (STEC) strains from meat, milk, and cheese samples collected in Germany between 2005 and 2006. All strains were investigated for their serotypes and for genetic variants of Shiga toxins 1 and 2 (Stx1 and Stx2). stx(1) or variant genes were detected in 88 (40.2%) strains and stx(2) and variants in 177 (80.8%) strains. Typing of stx genes was performed by stx-specific PCRs and by analysis of restriction fragment length polymorphisms (RFLP) of PCR products. Major genotypes of the Stx1 (stx(1), stx(1c), and stx(1d)) and the Stx2 (stx(2), stx(2d), stx(2-O118), stx(2e), and stx(2g)) families were detected, and multiple types of stx genes coexisted frequently in STEC strains. Only 1.8% of the STEC strains from food belonged to the classical enterohemorrhagic E. coli (EHEC) types O26:H11, O103:H2, and O157:H7, and only 5.0% of the STEC strains from food were positive for the eae gene, which is a virulence trait of classical EHEC. In contrast, 95 (43.4%) of the food-borne STEC strains carried stx(2) and/or mucus-activatable stx(2d) genes, an indicator for potential high virulence of STEC for humans. Most of these strains belonged to serotypes associated with severe illness in humans, such as O22:H8, O91:H21, O113:H21, O174:H2, and O174:H21. stx(2) and stx(2d) STEC strains were found frequently in milk and beef products. Other stx types were associated more frequently with pork (stx(2e)), lamb, and wildlife meat (stx(1c)). The combination of serotyping and stx genotyping was found useful for identification and for assignment of food-borne STEC to groups with potential lower and higher levels of virulence for humans. [Abstract/Link to Full Text]

Merod RT, Warren JE, McCaslin H, Wuertz S
Toward automated analysis of biofilm architecture: bias caused by extraneous confocal laser scanning microscopy images.
Appl Environ Microbiol. 2007 Aug;73(15):4922-30.
An increasing number of studies utilize confocal laser scanning microscopy (CLSM) for in situ visualization of biofilms and rely on the use of image analysis programs to extract quantitative descriptors of architecture. Recently, designed programs have begun incorporating procedures to automatically determine threshold values for three-dimensional CLSM image stacks. We have found that the automated threshold calculation is biased when a stack contains images lacking pixels of biological significance. Consequently, we have created the novel program Auto PHLIP-ML to resolve this bias by iteratively excluding extraneous images based on their area coverage of biomass. A procedure was developed to identify the optimal percent area coverage value used for extraneous image removal (PACVEIR). The optimal PACVEIR was defined to occur when the standard deviation of mean thickness, determined from replicate image stacks, was at a maximum, because it more accurately reflected inherent structural variation. Ten monoculture biofilms of either Ralstonia eutropha JMP228n::gfp or Acinetobacter sp. strain BD413 were tested to verify the routine. All biofilms exhibited an optimal PACVEIR between 0 and 1%. Prior to the exclusion of extraneous images, JMP228n::gfp appeared to develop more homogeneous biofilms than BD413. However, after the removal of extraneous images, JMP228n::gfp biofilms were found to form more heterogeneous biofilms. Similarly, JMP228n::gfp biofilms grown on glass surfaces vis-à-vis polyethylene membranes produced significantly different architectures after extraneous images had been removed but not when such images were included in threshold calculations. This study shows that the failure to remove extraneous images skewed a seemingly objective analysis of biofilm architecture and significantly altered statistically derived conclusions. [Abstract/Link to Full Text]

Albers E, Larsson C, Andlid T, Walsh MC, Gustafsson L
Effect of nutrient starvation on the cellular composition and metabolic capacity of Saccharomyces cerevisiae.
Appl Environ Microbiol. 2007 Aug;73(15):4839-48.
This investigation addresses the following question: what are the important factors for maintenance of a high catabolic capacity under various starvation conditions? Saccharomyces cerevisiae was cultured in aerobic batch cultures, and during the diauxic shift cells were transferred and subjected to 24 h of starvation. The following conditions were used: carbon starvation, nitrogen starvation in the presence of glucose or ethanol, and both carbon starvation and nitrogen starvation. During the starvation period changes in biomass composition (including protein, carbohydrate, lipid, and nucleic acid contents), metabolic activity, sugar transport kinetics, and the levels of selected enzymes were recorded. Subsequent to the starvation period the remaining catabolic capacity was measured by addition of 50 mM glucose. The results showed that the glucose transport capacity is a key factor for maintenance of high metabolic capacity in many, but not all, cases. The results for cells starved of carbon, carbon and nitrogen, or nitrogen in the presence of glucose all indicated that the metabolic capacity was indeed controlled by the glucose transport ability, perhaps with some influence of hexokinase, phosphofructokinase, aldolase, and enolase levels. However, it was also demonstrated that there was no such correlation when nitrogen starvation occurred in the presence of ethanol instead of glucose. [Abstract/Link to Full Text]

Roohparvar R, Huser A, Zwiers LH, De Waard MA
Control of Mycosphaerella graminicola on wheat seedlings by medical drugs known to modulate the activity of ATP-binding cassette transporters.
Appl Environ Microbiol. 2007 Aug;73(15):5011-9.
Medical drugs known to modulate the activity of human ATP-binding cassette (ABC) transporter proteins (modulators) were tested for the ability to potentiate the activity of the azole fungicide cyproconazole against in vitro growth of Mycosphaerella graminicola and to control disease development due to this pathogen on wheat seedlings. In vitro modulation of cyproconazole activity could be demonstrated in paper disk bioassays. Some of the active modulators (amitriptyline, flavanone, and phenothiazines) increased the accumulation of cyproconazole in M. graminicola, suggesting that they reversed cyproconazole efflux. However, synergism between cyproconazole and modulators against M. graminicola on wheat seedlings could not be shown. Despite their low in vitro toxicity to M. graminicola, some modulators (amitriptyline, loperamide, and promazine) did show significant intrinsic disease control activity in preventive and curative foliar spray tests with wheat seedlings. The results suggest that these compounds have indirect disease control activity based on modulation of fungal ABC transporters essential for virulence and constitute a new class of disease control agents. [Abstract/Link to Full Text]

Harris DM, van der Krogt ZA, van Gulik WM, van Dijken JP, Pronk JT
Formate as an auxiliary substrate for glucose-limited cultivation of Penicillium chrysogenum: impact on penicillin G production and biomass yield.
Appl Environ Microbiol. 2007 Aug;73(15):5020-5.
Production of beta-lactams by the filamentous fungus Penicillium chrysogenum requires a substantial input of ATP. During glucose-limited growth, this ATP is derived from glucose dissimilation, which reduces the product yield on glucose. The present study has investigated whether penicillin G yields on glucose can be enhanced by cofeeding of an auxiliary substrate that acts as an energy source but not as a carbon substrate. As a model system, a high-producing industrial strain of P. chrysogenum was grown in chemostat cultures on mixed substrates containing different molar ratios of formate and glucose. Up to a formate-to-glucose ratio of 4.5 mol.mol(-1), an increasing rate of formate oxidation via a cytosolic NAD(+)-dependent formate dehydrogenase increasingly replaced the dissimilatory flow of glucose. This resulted in increased biomass yields on glucose. Since at these formate-to-glucose ratios the specific penicillin G production rate remained constant, the volumetric productivity increased. Metabolic modeling studies indicated that formate transport in P. chrysogenum does not require an input of free energy. At formate-to-glucose ratios above 4.5 mol.mol(-1), the residual formate concentrations in the cultures increased, probably due to kinetic constraints in the formate-oxidizing system. The accumulation of formate coincided with a loss of the coupling between formate oxidation and the production of biomass and penicillin G. These results demonstrate that, in principle, mixed-substrate feeding can be used to increase the yield on a carbon source of assimilatory products such as beta-lactams. [Abstract/Link to Full Text]

Lindner SN, Vidaurre D, Willbold S, Schoberth SM, Wendisch VF
NCgl2620 encodes a class II polyphosphate kinase in Corynebacterium glutamicum.
Appl Environ Microbiol. 2007 Aug;73(15):5026-33.
Corynebacterium glutamicum is able to accumulate up to 600 mM cytosolic phosphorus in the form of polyphosphate (poly P). Granular poly P (volutin) can make up to 37% of the internal cell volume. This bacterium lacks the classic enzyme of poly P synthesis, class I polyphosphate kinase (PPK1), but it possesses two genes, ppk2A (corresponds to NCgl0880) and ppk2B (corresponds to NCgl2620), for putative class II (PPK2) PPKs. Deletion of ppk2B decreased PPK activity and cellular poly P content, while overexpression of ppk2B increased both PPK activity and cellular poly P content. Neither deletion nor overexpression of ppk2A changed specific activity of PPK or cellular poly P content significantly. Purified PPK2B of C. glutamicum is active as a homotetramer and formed poly P with an average chain length of about 125, as determined with (31)P nuclear magnetic resonance. The catalytic efficiency of C. glutamicum PPK2B was higher in the poly P-forming direction than for nucleoside triphosphate formation from poly P. The ppk2B deletion mutant, which accumulated very little poly P and grew as C. glutamicum wild type under phosphate-sufficient conditions, showed a growth defect under phosphate-limiting conditions. [Abstract/Link to Full Text]

Koike S, Krapac IG, Oliver HD, Yannarell AC, Chee-Sanford JC, Aminov RI, Mackie RI
Monitoring and source tracking of tetracycline resistance genes in lagoons and groundwater adjacent to swine production facilities over a 3-year period.
Appl Environ Microbiol. 2007 Aug;73(15):4813-23.
To monitor the dissemination of resistance genes into the environment, we determined the occurrence of tetracycline resistance (Tc(r)) genes in groundwater underlying two swine confinement operations. Monitoring well networks (16 wells at site A and 6 wells at site C) were established around the lagoons at each facility. Groundwater (n = 124) and lagoon (n = 12) samples were collected from the two sites at six sampling times from 2000 through 2003. Total DNA was extracted, and PCR was used to detect seven Tc(r) genes [tet(M), tet(O), tet(Q), tet(W), tet(C), tet(H), and tet(Z)]. The concentration of Tc(r) genes was quantified by real-time quantitative PCR. To confirm the Tc(r) gene source in groundwater, comparative analysis of tet(W) gene sequences was performed on groundwater and lagoon samples. All seven Tc(r) genes were continually detected in groundwater during the 3-year monitoring period at both sites. At site A, elevated detection frequency and concentration of Tc(r) genes were observed in the wells located down-gradient of the lagoon. Comparative analysis of tet(W) sequences revealed that the impacted groundwater contained gene sequences almost identical (99.8% identity) to those in the lagoon, but these genes were not found in background libraries. Novel sequence clusters and unique indigenous resistance gene pools were also found in the groundwater. Thus, antibiotic resistance genes in groundwater are affected by swine manure, but they are also part of the indigenous gene pool. [Abstract/Link to Full Text]

Yu M, Faan YW, Chung WY, Tsang JS
Isolation and characterization of a novel haloacid permease from Burkholderia cepacia MBA4.
Appl Environ Microbiol. 2007 Aug;73(15):4874-80.
Burkholderia cepacia MBA4 is a bacterium that can utilize 2-haloacids as carbon and energy sources for growth. It has been proposed that dehalogenase-associated permease mediates the uptake of haloacid. In this paper, we report the first cloning and characterization of such a haloacid permease. The structural gene, designated deh4p, was found 353 bases downstream of the dehalogenase gene deh4a. Quantitative analysis of the expression of deh4p showed that it was induced by monochloroacetate (MCA), to a level similar to the MCA-induced level of deh4a. The nucleotide sequence of deh4p was determined, and an open reading frame of 1,656 bp encoding a putative peptide of 552 amino acids was identified. Deh4p has a putative molecular weight of 59,414 and an isoelectric point of 9.88. Deh4p has the signatures of sugar transport proteins and integral membrane proteins of the major facilitator superfamily. Uptake of [(14)C]MCA into the cell was Deh4p dependent. Deh4p has apparent K(m)s of 5.5 and 8.9 muM and V(max)s of 9.1 and 23.1 nmol mg(-1) min(-1) for acetate and MCA, respectively. A mutant with a transposon-inactivated haloacid operon failed to grow on MCA even when deh4a was provided in trans. [Abstract/Link to Full Text]

Elshahed MS, Youssef NH, Luo Q, Najar FZ, Roe BA, Sisk TM, Bühring SI, Hinrichs KU, Krumholz LR
Phylogenetic and metabolic diversity of Planctomycetes from anaerobic, sulfide- and sulfur-rich Zodletone Spring, Oklahoma.
Appl Environ Microbiol. 2007 Aug;73(15):4707-16.
We investigated the phylogenetic diversity and metabolic capabilities of members of the phylum Planctomycetes in the anaerobic, sulfide-saturated sediments of a mesophilic spring (Zodletone Spring) in southwestern Oklahoma. Culture-independent analyses of 16S rRNA gene sequences generated using Planctomycetes-biased primer pairs suggested that an extremely diverse community of Planctomycetes is present at the spring. Although sequences that are phylogenetically affiliated with cultured heterotrophic Planctomycetes were identified, the majority of the sequences belonged to several globally distributed, as-yet-uncultured Planctomycetes lineages. Using complex organic media (aqueous extracts of the spring sediments and rumen fluid), we isolated two novel strains that belonged to the Pirellula-Rhodopirellula-Blastopirellula clade within the Planctomycetes. The two strains had identical 16S rRNA gene sequences, and their closest relatives were isolates from Kiel Fjord (Germany), Keauhou Beach (HI), a marine aquarium, and tissues of marine organisms (Aplysina sp. sponges and postlarvae of the giant tiger prawn Penaeus monodon). The closest recognized cultured relative of strain Zi62 was Blastopirellula marina (93.9% sequence similarity). Detailed characterization of strain Zi62 revealed its ability to reduce elemental sulfur to sulfide under anaerobic conditions, as well as its ability to produce acids from sugars; both characteristics may potentially allow strain Zi62 to survive and grow in the anaerobic, sulfide- and sulfur-rich environment at the spring source. Overall, this work indicates that anaerobic metabolic abilities are widely distributed among all major Planctomycetes lineages and suggests carbohydrate fermentation and sulfur reduction as possible mechanisms employed by heterotrophic Planctomycetes for growth and survival under anaerobic conditions. [Abstract/Link to Full Text]

Wijnands LM, Dufrenne JB, van Leusden FM, Abee T
Germination of Bacillus cereus spores is induced by germinants from differentiated Caco-2 Cells, a human cell line mimicking the epithelial cells of the small intestine.
Appl Environ Microbiol. 2007 Aug;73(15):5052-4.
Spores of 11 enterotoxigenic strains of Bacillus cereus isolated from foods and humans adhered with similar efficiencies to Caco-2 cells, whereas subsequent germination triggering was observed with only 8 of these strains. Notably, Hep-2 cells did not trigger germination, while spores of all strains displayed similar germination efficiencies in brain heart infusion broth. [Abstract/Link to Full Text]

Kitphati W, Ngok-Ngam P, Suwanmaneerat S, Sukchawalit R, Mongkolsuk S
Agrobacterium tumefaciens fur has important physiological roles in iron and manganese homeostasis, the oxidative stress response, and full virulence.
Appl Environ Microbiol. 2007 Aug;73(15):4760-8.
In Agrobacterium tumefaciens, the balance between acquiring enough iron and avoiding iron-induced toxicity is regulated in part by Fur (ferric uptake regulator). A fur mutant was constructed to address the physiological role of the regulator. Atypically, the mutant did not show alterations in the levels of siderophore biosynthesis and the expression of iron transport genes. However, the fur mutant was more sensitive than the wild type to an iron chelator, 2,2'-dipyridyl, and was also more resistant to an iron-activated antibiotic, streptonigrin, suggesting that Fur has a role in regulating iron concentrations. A. tumefaciens sitA, the periplasmic binding protein of a putative ABC-type iron and manganese transport system (sitABCD), was strongly repressed by Mn(2+) and, to a lesser extent, by Fe(2+), and this regulation was Fur dependent. Moreover, the fur mutant was more sensitive to manganese than the wild type. This was consistent with the fact that the fur mutant showed constitutive up-expression of the manganese uptake sit operon. Fur(At) showed a regulatory role under iron-limiting conditions. Furthermore, Fur has a role in determining oxidative resistance levels. The fur mutant was hypersensitive to hydrogen peroxide and had reduced catalase activity. The virulence assay showed that the fur mutant had a reduced ability to cause tumors on tobacco leaves compared to wild-type NTL4. [Abstract/Link to Full Text]

den Besten HM, Ingham CJ, van Hylckama Vlieg JE, Beerthuyzen MM, Zwietering MH, Abee T
Quantitative analysis of population heterogeneity of the adaptive salt stress response and growth capacity of Bacillus cereus ATCC 14579.
Appl Environ Microbiol. 2007 Aug;73(15):4797-804.
Bacterial populations can display heterogeneity with respect to both the adaptive stress response and growth capacity of individual cells. The growth dynamics of Bacillus cereus ATCC 14579 during mild and severe salt stress exposure were investigated for the population as a whole in liquid culture. To quantitatively assess the population heterogeneity of the stress response and growth capacity at a single-cell level, a direct imaging method was applied to monitor cells from the initial inoculum to the microcolony stage. Highly porous Anopore strips were used as a support for the culturing and imaging of microcolonies at different time points. The growth kinetics of cells grown in liquid culture were comparable to those of microcolonies grown upon Anopore strips, even in the presence of mild and severe salt stress. Exposure to mild salt stress resulted in growth that was characterized by a remarkably low variability of microcolony sizes, and the distributions of the log(10)-transformed microcolony areas could be fitted by the normal distribution. Under severe salt stress conditions, the microcolony sizes were highly heterogeneous, and this was apparently caused by the presence of both a nongrowing and growing population. After discriminating these two subpopulations, it was shown that the variability of microcolony sizes of the growing population was comparable to that of non-salt-stressed and mildly salt-stressed populations. Quantification of population heterogeneity during stress exposure may contribute to an optimized application of preservation factors for controlling growth of spoilage and pathogenic bacteria to ensure the quality and safety of minimally processed foods. [Abstract/Link to Full Text]

Rodríguez-Echeverría S, Crisóstomo JA, Freitas H
Genetic diversity of rhizobia associated with Acacia longifolia in two stages of invasion of coastal sand dunes.
Appl Environ Microbiol. 2007 Aug;73(15):5066-70.
We examined the genetic diversity of root nodule bacteria associated with the Australian legume Acacia longifolia in two stages of invasion of a coastal sand dune system. All isolates belonged to the genus Bradyrhizobium. A higher diversity was found in the long-established trees. The results suggest the introduction of exotic bradyrhizobia with the plant. [Abstract/Link to Full Text]

Wisselink HW, Toirkens MJ, del Rosario Franco Berriel M, Winkler AA, van Dijken JP, Pronk JT, van Maris AJ
Engineering of Saccharomyces cerevisiae for efficient anaerobic alcoholic fermentation of L-arabinose.
Appl Environ Microbiol. 2007 Aug;73(15):4881-91.
For cost-effective and efficient ethanol production from lignocellulosic fractions of plant biomass, the conversion of not only major constituents, such as glucose and xylose, but also less predominant sugars, such as l-arabinose, is required. Wild-type strains of Saccharomyces cerevisiae, the organism used in industrial ethanol production, cannot ferment xylose and arabinose. Although metabolic and evolutionary engineering has enabled the efficient alcoholic fermentation of xylose under anaerobic conditions, the conversion of l-arabinose into ethanol by engineered S. cerevisiae strains has previously been demonstrated only under oxygen-limited conditions. This study reports the first case of fast and efficient anaerobic alcoholic fermentation of l-arabinose by an engineered S. cerevisiae strain. This fermentation was achieved by combining the expression of the structural genes for the l-arabinose utilization pathway of Lactobacillus plantarum, the overexpression of the S. cerevisiae genes encoding the enzymes of the nonoxidative pentose phosphate pathway, and extensive evolutionary engineering. The resulting S. cerevisiae strain exhibited high rates of arabinose consumption (0.70 g h(-1) g [dry weight](-1)) and ethanol production (0.29 g h(-1) g [dry weight](-1)) and a high ethanol yield (0.43 g g(-1)) during anaerobic growth on l-arabinose as the sole carbon source. In addition, efficient ethanol production from sugar mixtures containing glucose and arabinose, which is crucial for application in industrial ethanol production, was achieved. [Abstract/Link to Full Text]

Paredes CJ, Senger RS, Spath IS, Borden JR, Sillers R, Papoutsakis ET
A general framework for designing and validating oligomer-based DNA microarrays and its application to Clostridium acetobutylicum.
Appl Environ Microbiol. 2007 Jul;73(14):4631-8.
While DNA microarray analysis is widely accepted as an essential tool for modern biology, its use still eludes many researchers for several reasons, especially when microarrays are not commercially available. In that case, the design, construction, and use of microarrays for a sequenced organism constitute substantial, time-consuming, and expensive tasks. Recently, it has become possible to construct custom microarrays using industrial manufacturing processes, which offer several advantages, including speed of manufacturing, quality control, no up-front setup costs, and need-based microarray ordering. Here, we describe a strategy for designing and validating DNA microarrays manufactured using a commercial process. The 22K microarrays for the solvent producer Clostridium acetobutylicum ATCC 824 are based on in situ-synthesized 60-mers employing the Agilent technology. The strategy involves designing a large library of possible oligomer probes for each target (i.e., gene or DNA sequence) and experimentally testing and selecting the best probes for each target. The degenerate C. acetobutylicum strain M5 lacking the pSOL1 megaplasmid (with 178 annotated open reading frames [genes]) was used to estimate the level of probe cross-hybridization in the new microarrays and to establish the minimum intensity for a gene to be considered expressed. Results obtained using this microarray design were consistent with previously reported results from spotted cDNA-based microarrays. The proposed strategy is applicable to any sequenced organism. [Abstract/Link to Full Text]

Guinane CM, Cotter PD, Lawton EM, Hill C, Ross RP
Insertional mutagenesis to generate lantibiotic resistance in Lactococcus lactis.
Appl Environ Microbiol. 2007 Jul;73(14):4677-80.
While the potential emergence of food spoilage and pathogenic bacteria with resistance to lantibiotics is a concern, the creation of derivatives of starter cultures and adjuncts that can grow in the presence of these antimicrobials may have applications in food fermentations. Here a bank of Lactococcus lactis IL1403 mutants was created and screened, and a number of novel genetic loci involved in lantibiotic resistance were identified. [Abstract/Link to Full Text]

Moran MA, Belas R, Schell MA, González JM, Sun F, Sun S, Binder BJ, Edmonds J, Ye W, Orcutt B, Howard EC, Meile C, Palefsky W, Goesmann A, Ren Q, Paulsen I, Ulrich LE, Thompson LS, Saunders E, Buchan A
Ecological genomics of marine Roseobacters.
Appl Environ Microbiol. 2007 Jul;73(14):4559-69.
Bacterioplankton of the marine Roseobacter clade have genomes that reflect a dynamic environment and diverse interactions with marine plankton. Comparative genome sequence analysis of three cultured representatives suggests that cellular requirements for nitrogen are largely provided by regenerated ammonium and organic compounds (polyamines, allophanate, and urea), while typical sources of carbon include amino acids, glyoxylate, and aromatic metabolites. An unexpectedly large number of genes are predicted to encode proteins involved in the production, degradation, and efflux of toxins and metabolites. A mechanism likely involved in cell-to-cell DNA or protein transfer was also discovered: vir-related genes encoding a type IV secretion system typical of bacterial pathogens. These suggest a potential for interacting with neighboring cells and impacting the routing of organic matter into the microbial loop. Genes shared among the three roseobacters and also common in nine draft Roseobacter genomes include those for carbon monoxide oxidation, dimethylsulfoniopropionate demethylation, and aromatic compound degradation. Genes shared with other cultured marine bacteria include those for utilizing sodium gradients, transport and metabolism of sulfate, and osmoregulation. [Abstract/Link to Full Text]

Atterbury RJ, Van Bergen MA, Ortiz F, Lovell MA, Harris JA, De Boer A, Wagenaar JA, Allen VM, Barrow PA
Bacteriophage therapy to reduce salmonella colonization of broiler chickens.
Appl Environ Microbiol. 2007 Jul;73(14):4543-9.
Acute enteric infections caused by salmonellas remain a major public health burden worldwide. Poultry, particularly chickens, are known to be the main reservoir for this zoonotic pathogen. Although some progress has been made in reducing Salmonella colonization of broiler chickens by using biosecurity and antimicrobials, it still remains a considerable problem. The use of host-specific bacteriophages as a biocontrol is one possible intervention by which Salmonella colonization could be reduced. A total of 232 Salmonella bacteriophages were isolated from poultry farms, abattoirs, and wastewater in 2004 and 2005. Three phages exhibiting the broadest host ranges against Salmonella enterica serotypes Enteritidis, Hadar, and Typhimurium were characterized further by determining their morphology and lytic activity in vitro. These phages were then administered in antacid suspension to birds experimentally colonized with specific Salmonella host strains. The first phage reduced S. enterica serotype Enteritidis cecal colonization by > or = 4.2 log10 CFU within 24 h compared with controls. Administration of the second phage reduced S. enterica serotype Typhimurium by > or = 2.19 log10 CFU within 24 h. The third bacteriophage was ineffective at reducing S. enterica serotype Hadar colonization. Bacteriophage resistance occurred at a frequency commensurate with the titer of phage being administered, with larger phage titers resulting in a greater proportion of resistant salmonellas. The selection of appropriate bacteriophages and optimization of both the timing and method of phage delivery are key factors in the successful phage-mediated control of salmonellas in broiler chickens. [Abstract/Link to Full Text]

Gerba CP, Kennedy D
Enteric virus survival during household laundering and impact of disinfection with sodium hypochlorite.
Appl Environ Microbiol. 2007 Jul;73(14):4425-8.
This study was conducted to determine whether enteric viruses (adenovirus, rotavirus, and hepatitis A virus) added to cotton cloth swatches survive the wash cycle, the rinse cycle, and a 28-min permanent press drying cycle as commonly practiced in households in the United States. Detergent with and without bleach (sodium hypochlorite) was added to washing machines containing sterile and virus-inoculated 58-cm2 swatches, 3.2 kg of cotton T-shirts and underwear, and a soiled pillowcase designed to simulate the conditions (pH, organic load, etc.) encountered in soiled laundry. The most important factors for the reduction of virus in laundry were passage through the drying cycle and the addition of sodium hypochlorite. Washing with detergent alone was not found to be effective for the removal or inactivation of enteric viruses, as significant concentrations of virus were found on the swatches (reductions of 92 to 99%). It was also demonstrated that viruses are readily transferred from contaminated cloths to uncontaminated clothes. The use of sodium hypochlorite reduced the number of infectious viruses on the swatches after washing and drying by at least 99.99%. Laundering practices in common use in the United States do not eliminate enteric and respiratory viruses from clothes. The use of bleach can further reduce the numbers of enteric viruses in laundry. [Abstract/Link to Full Text]

Burt SA, van der Zee R, Koets AP, de Graaff AM, van Knapen F, Gaastra W, Haagsman HP, Veldhuizen EJ
Carvacrol induces heat shock protein 60 and inhibits synthesis of flagellin in Escherichia coli O157:H7.
Appl Environ Microbiol. 2007 Jul;73(14):4484-90.
The essential oils of oregano and thyme are active against a number of food-borne pathogens, such as Escherichia coli O157:H7. Carvacrol is one of the major antibacterial components of these oils, and p-cymene is thought to be its precursor in the plant. The effects of carvacrol and p-cymene on protein synthesis in E. coli O157:H7 ATCC 43895 cells were investigated. Bacteria were grown overnight in Mueller-Hinton broth with a sublethal concentration of carvacrol or p-cymene, and their protein compositions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and confirmed by Western blotting. The presence of 1 mM carvacrol during overnight incubation caused E. coli O157:H7 to produce significant amounts of heat shock protein 60 (HSP60) (GroEL) (P < 0.05) and inhibited the synthesis of flagellin highly significantly (P < 0.001), causing cells to be aflagellate and therefore nonmotile. The amounts of HSP70 (DnaK) were not significantly affected. p-Cymene at 1 mM or 10 mM did not induce HSP60 or HSP70 in significant amounts and did not have a significant effect on flagellar synthesis. Neither carvacrol (0.3, 0.5, 0.8, or 1 mM) nor p-cymene (0.3, 0.5, or 0.8 mM) treatment of cells in the mid-exponential growth phase induced significant amounts of HSP60 or HSP70 within 3 h, although numerical increases of HSP60 were observed. Motility decreased with increasing concentrations of both compounds, but existing flagella were not shed. This study is the first to demonstrate that essential oil components induce HSP60 in bacteria and that overnight incubation with carvacrol prevents the development of flagella in E. coli O157:H7. [Abstract/Link to Full Text]

Hotto AM, Satchwell MF, Boyer GL
Molecular characterization of potential microcystin-producing cyanobacteria in Lake Ontario embayments and nearshore waters.
Appl Environ Microbiol. 2007 Jul;73(14):4570-8.
The distribution and genotypic variation of potential microcystin (MC) producers along the southern and eastern shores of Lake Ontario in 2001 and 2003 were examined using a suite of PCR primers. Cyanobacterial, Microcystis sp., and Microcystis-specific toxin primer sets identified shoreline distribution of cyanobacterial DNA (in 97% of the stations) and MC synthetase genes (in 50% of the stations). Sequence analysis of a partial mcyA amplicon targeting Microcystis, Anabaena, and Planktothrix species indicated that the Microcystis sp. genotype was the dominant MC genotype present and revealed a novel Microcystis-like sequence containing a 6-bp insert. Analysis of the same samples with genus-specific mcyE primers confirmed that the Microcystis sp. genotype was the dominant potential MC producer. Genotype compositions within embayments were relatively homogenous compared to those for shoreline and tributary samples. MC concentrations along the shoreline exhibited both temporal and spatial differences as evidenced by the protein phosphatase inhibition assay, at times exceeding the World Health Organization guideline value for drinking water of 1.0 microg MC-LReq liter(-1). MC genotypes are widespread along the New York State shoreline of Lake Ontario, appear to originate nearshore, and can be carried through the lake via wind and surface water current patterns. [Abstract/Link to Full Text]

Ma YF, Wu JF, Wang SY, Jiang CY, Zhang Y, Qi SW, Liu L, Zhao GP, Liu SJ
Nucleotide sequence of plasmid pCNB1 from comamonas strain CNB-1 reveals novel genetic organization and evolution for 4-chloronitrobenzene degradation.
Appl Environ Microbiol. 2007 Jul;73(14):4477-83.
The nucleotide sequence of a new plasmid pCNB1 from Comamonas sp. strain CNB-1 that degrades 4-chloronitrobenzene (4CNB) was determined. pCNB1 belongs to the IncP-1beta group and is 91,181 bp in length. A total of 95 open reading frames appear to be involved in (i) the replication, maintenance, and transfer of pCNB1; (ii) resistance to arsenate and chromate; and (iii) the degradation of 4CNB. The 4CNB degradative genes and arsenate resistance genes were located on an extraordinarily large transposon (44.5 kb), proposed as TnCNB1. TnCNB1 was flanked by two IS1071 elements and represents a new member of the composite I transposon family. The 4CNB degradative genes within TnCNB1 were separated by various truncated genes and genetic homologs from other DNA molecules. Genes for chromate resistance were located on another transposon that was similar to the Tn21 transposon of the class II replicative family that is frequently responsible for the mobilization of mercury resistance genes. Resistance to arsenate and chromate were experimentally confirmed, and transcriptions of arsenate and chromate resistance genes were demonstrated by reverse transcription-PCR. These results described a new member of the IncP-1beta plasmid family, and the findings suggest that gene deletion and acquisition as well as genetic rearrangement of DNA molecules happened during the evolution of the 4CNB degradation pathway on pCNB1. [Abstract/Link to Full Text]

Woebken D, Fuchs BM, Kuypers MM, Amann R
Potential interactions of particle-associated anammox bacteria with bacterial and archaeal partners in the Namibian upwelling system.
Appl Environ Microbiol. 2007 Jul;73(14):4648-57.
Recent studies have shown that the anaerobic oxidation of ammonium by anammox bacteria plays an important role in catalyzing the loss of nitrogen from marine oxygen minimum zones (OMZ). However, in situ oxygen concentrations of up to 25 microM and ammonium concentrations close to or below the detection limit in the layer of anammox activity are hard to reconcile with the current knowledge of the physiology of anammox bacteria. We therefore investigated samples from the Namibian OMZ by comparative 16S rRNA gene analysis and fluorescence in situ hybridization. Our results showed that "Candidatus Scalindua" spp., the typical marine anammox bacteria, colonized microscopic particles that were likely the remains of either macroscopic marine snow particles or resuspended particles. These particles were slightly but significantly (P < 0.01) enriched in Gammaproteobacteria (11.8% +/- 5.0%) compared to the free-water phase (8.1% +/- 1.8%). No preference for the attachment to particles could be observed for members of the Alphaproteobacteria and Bacteroidetes, which were abundant (12 to 17%) in both habitats. The alphaproteobacterial SAR11 clade, the Euryarchaeota, and group I Crenarchaeota, were all significantly depleted in particles compared to their presence in the free-water phase (16.5% +/- 3.5% versus 2.6% +/- 1.7%, 2.7% +/- 1.9% versus <1%, and 14.9% +/- 4.6% versus 2.2% +/- 1.8%, respectively, all P < 0.001). Sequence analysis of the crenarchaeotal 16S rRNA genes showed a 99% sequence identity to the nitrifying "Nitrosopumilus maritimus." Even though we could not observe conspicuous consortium-like structures of anammox bacteria with particle-enriched bacterioplankton groups, we hypothesize that members of Gammaproteobacteria, Alphaproteobacteria, and Bacteroidetes play a critical role in extending the anammox reaction to nutrient-depleted suboxic water layers in the Namibian upwelling system by creating anoxic, nutrient-enriched microniches. [Abstract/Link to Full Text]

Miyake R, Kawamoto J, Wei YL, Kitagawa M, Kato I, Kurihara T, Esaki N
Construction of a low-temperature protein expression system using a cold-adapted bacterium, Shewanella sp. strain Ac10, as the host.
Appl Environ Microbiol. 2007 Aug;73(15):4849-56.
A recombinant protein expression system working at low temperatures is expected to be useful for the production of thermolabile proteins. We constructed a low-temperature expression system using an Antarctic cold-adapted bacterium, Shewanella sp. strain Ac10, as the host. We evaluated the promoters for proteins abundantly produced at 4 degrees C in this bacterium to express foreign proteins. We used 27 promoters and a broad-host-range vector, pJRD215, to produce beta-lactamase in Shewanella sp. strain Ac10. The maximum yield was obtained when the promoter for putative alkyl hydroperoxide reductase (AhpC) was used and the recombinant cells were grown to late stationary phase. The yield was 91 mg/liter of culture at 4 degrees C and 139 mg/liter of culture at 18 degrees C. We used this system to produce putative peptidases, PepF, LAP, and PepQ, and a putative glucosidase, BglA, from a psychrophilic bacterium, Desulfotalea psychrophila DSM12343. We obtained 48, 7.1, 28, and 5.4 mg/liter of culture of these proteins, respectively, in a soluble fraction. The amounts of PepF and PepQ produced by this system were greater than those produced by the Escherichia coli T7 promoter system. [Abstract/Link to Full Text]


Recent Articles in Applied Microbiology

Bayne HG, Michener HD
Growth of Staphylococcus and Salmonella on frankfurters with and without sodium nitrite.
Appl Microbiol. 1975 Nov;30(5):844-9.
Conventional and nitrite-free frankfurters in loosely wrapped packages were compared as to their ability to support growth of Salmonella, Staphylococcus, and their naturally occurring spoilage flora at 7 C (simulating refrigerated storage) and 20 C (simulating possible temperature abuse). At 7 C Salmonella did not grow in either type of frankfurter; Staphylococcus and the natural spoilage flora sometimes grew more rapidly in the absence of nitrite, but the difference was not significant. At 20 C growth of Salmonella, Staphylococcus, and of the spoilage flora was, at most, only slightly faster on nitrite-free frankfurters. Salmonella was not suppressed in broth culture experiments the pH and nitrite content found in frankfurters. Although either type of frankfurter can become hazardous due to growth of Salmonella or Staphylococcus, no unusual or additional hazard resulted from the omission of nitrite from frankfurters. [Abstract/Link to Full Text]

Smith JL, Huhtanen CN, Kissinger JC, Palumbo SA
Survival of salmonellae during pepperoni manufacture.
Appl Microbiol. 1975 Nov;30(5):759-63.
Survival of salmonellae in artificially contaminated beef-pork mixtures (approximately 10(4) salmonellae/g) was studied in pepperoni prepared by either a natural flora or lactic starter culture fermentation or in nonfermented sausages. The pepperoni did not become salmonellae free during the usual commercial 15 to 30-day drying period. Salmonella dublin was present in all products, fermented or unfermented, after 42 to 43 days of drying. At a lower level of contamination, 10(3)/g, S. dublin could not be recovered from starter culture-fermented pepperoni after 14 days of drying but persisted in the natural flora-fermented sausage. S. typhimurium (initial count, 10(4)/g) was absent after 42 days of drying when starter culture was used to ferment the pepperoni, but was still present in the natural flora-fermented and unfermented products. S. dublin, host adapted to cattle, or S. choleraesuis, host adapted to swine, had similar survival patterns in beef pork, or beef-pork pepperoni. Heating salmonellae contaminated beef-pork pepperoni (after fermantation but before drying) to an internal temperature of 60 C (trichinae inactivating) eliminated the food-borne pathogen from the sausage product. [Abstract/Link to Full Text]

Humber JY, Denny CB, Bohrer CW
Influence of pH on the heat inactivation of staphylococcal enterotoxin A as determined by monkey feeding and serological assay.
Appl Microbiol. 1975 Nov;30(5):755-8.
The effect of pH on the thermal inactivation of staphylococcal enterotoxin A was investigated. Analysis of heated toxin by immunodiffusion in gel indicated that enterotoxin A in beef bouillon was inactivated faster at pH 5.3 than at pH 6.2. The z values (slopes) for the heat inactivation curves at pH 6.2 and 5.3 were 49.5 and 55 F (about 27 and 30 C), respectively. Enterotoxin produced and heated in dialyzed Casamino Acids medium and assayed by monkey feeding was more easily inactivated by heat at pH 5.3 than at pH 7.8. Thermal inactivation curves for enterotoxin A in beef bouillon (5 mug/ml, pH 5.3) were determined by two methods, monkey feeding and serological assay. The z values for the curves obtained by these two methods were both 55 F, although loss of biological or toxic activity of the enterotoxin occurred before loss of serological activity. [Abstract/Link to Full Text]

Foster TL, Winans L
Psychrophilic microorganisms from areas associated with the Viking spacecraft.
Appl Microbiol. 1975 Oct;30(4):546-50.
Microorganisms capable of growth at 7 C were enumerated and isolated from soil samples from the manufacture and assembly areas of the Viking spacecraft. Populations ranging from 4.2 X 10(3) to 7.7 X 10(6)/g of soil were isolated from the 15 soil samples examined. Temperature requirements were determined, and those growing at 3 C, but not at 32 C, were designated as obligate psychrophiles in this investigation. Populations of soil bacteria, including aerobic sporeformers, ranging from 1.5 X 10(2) to 9.8 X 10(5)/g were capable of growth at 3 C, but not at 32 C. Bacterial isolates were identified to major generic groups. No psychrophilic sporeformers were isolated from soil from the manufacture area, but psychrophilic sporeformers ranged from 0 to 6.1 X 10(3)/g from soil from the assembly area. [Abstract/Link to Full Text]

O'toole DK
Effect of Incubation Conditions at 55 C on Moisture Loss from Agar Plates.
Appl Microbiol. 1975 Oct;30(4):692-693.
The percentage of moisture loss was least from plates incubated in plastic bags, sealed jars, or in a humid chamber. There was a stacking effect noted in plates incubated in plastic bags and sealed jars. [Abstract/Link to Full Text]

Sheldon RB, Boylen CW
Factors Affecting the Contribution by Epiphytic Algae to the Primary Productivity of an Oligotrophic Freshwater Lake.
Appl Microbiol. 1975 Oct;30(4):657-667.
A diatom-dominated population of epiphytic algae was studied in an oligotrophic lake to determine the factors which limit epiphyte growth and to measure their contribution to primary productivity. Algae were collected from plants growing at four sites in Lake George, N.Y., during the spring, summer, and fall of 1974. Samples were taken from 3 m, corresponding to the depth at which macrophytes were most productive. Algae exhibited an optimum temperature for HCO(3) uptake at 30 C, although the summer littoral lake temperature ranged from 18 to 25 C. Light saturation occurred at an intensity of 8,608 lux, approximating the environmental intensity at the depth from which algae were taken. Epiphytes exhibited their maximum photosynthetic capacity of 0.6 mg of carbon fixed/m of macrophyte surface area per h in the early afternoon in mid-August. They assimilated approximately 5% as much inorganic carbon as the macrophytes from which they were taken. Epiphyte population densities followed the seasonal growth patterns of the macrophytes, with maximal leaf colonization remaining essentially constant relative to the leaf position on the plant. There was little change in density between sampling sites at any given time. Productivities of epiphytes from bottom leaves were 10-fold greater than those of epiphytes from top leaves. Addition of PO(4), NO(3), NH(3), Si, and SO(4) had no stimulatory effect on photosynthesis. Addition of HCO(3) stimulated photosynthesis greater than 30%, suggesting that carbon may be a limiting nutrient for epiphytic algae in Lake George. [Abstract/Link to Full Text]

Wardle MD, Renninger GM
Bactericidal effect of hydrogen peroxide on spacecraft isolates.
Appl Microbiol. 1975 Oct;30(4):710-1.
Solutions of 3, 10, and 15% hydrogen peroxide were found to have pronounced bactericidal effects, as a function of time of exposure, on sporeformers and non-sporeformers isolated from spacecraft. [Abstract/Link to Full Text]

Oremland RS, Taylor BF
Inhibition of methanogenesis in marine sediments by acetylene and ethylene: validity of the acetylene reduction assay for anaerobic microcosms.
Appl Microbiol. 1975 Oct;30(4):707-9.
Methanogenesis was irreversibly inhibited in sediments by concentrations of acetylene employed in nitrogen fixation assays (1 to 20%, vol/vol). Ethylene, but not ethane, also stopped methane production, and the inhibition was reversed by gassing with hydrogen. [Abstract/Link to Full Text]

Halls NA, Ayres JC
Factors affecting the production of sterigmatocystin in semisynthetic media.
Appl Microbiol. 1975 Oct;30(4):702-3.
Production of sterigmatocystin by Aspergillus versicolor was stimulated by inorganic phosphate when used in conjunction with citric acid cycle compounds. [Abstract/Link to Full Text]

Bukovic JA, Johnson HM
Staphylococcal enterotoxin C: solid-phase radioimmunoassay.
Appl Microbiol. 1975 Oct;30(4):700-1.
A solid-phase radioimmunoassay test employing 125I-labeled enterotoxin C and polystyrene tubes coated with specific antibody was used for the detection and quantitation of entertoxin C in condensed milk, cheddar cheese, custard, and ham salad. The assay was sensitive to 1 to 10 ng of toxin per g of food; nonspecific inhibitions were 16% or less. [Abstract/Link to Full Text]

Koltin Y, Day PR
Specificity of Ustilago maydis killer proteins.
Appl Microbiol. 1975 Oct;30(4):694-6.
Bacteria and fungi were tested for sensitivity to Ustilago maydis killer strains carrying virus-like particles. Various species taxonomically related to U. maydis were sensitive. [Abstract/Link to Full Text]

Bauchop T, Clarke RT, Newhook JC
Scanning electron microscope study of bacteria associated with the rumen epithelium of sheep.
Appl Microbiol. 1975 Oct;30(4):668-75.
Examination of the rumen epithelium of sheep by scanning electron microscopy revealed bacteria associated with the epithelial surface. Comparison of epithelial surfaces from 10 sheep revealed areas that were consistently densely covered with bacteria and other areas where the cover was consistently light. The bacterial populations were frequently of mixed morphological types, but areas populated with a single type were also observed. This finding, together with the discovery of bacterial forms not previously described in rumen contents, suggests that a specific flora may exist on the rumen epithelial surface. The functional significance of such a population is discussed. [Abstract/Link to Full Text]

Schwarz JR, Colwell RR
Heterotrophic activity of deep-sea sediment bacteria.
Appl Microbiol. 1975 Oct;30(4):639-49.
Sediment samples, containing mixed microbial populations that were decompressed during retrieval from 7,750 and 8,130 m in the Puerto Rican Trench, were recompressed and incubated at the approximate in situ temperature (3 C) and pressure (775 or 815 atm) in the presence of 14C-labeled amino acids. Heterotrophic activity (total uptake, CO2 respiration, and cellular assimilation) and cellular-associated "pool" concentrations were measured. Compared with atmospheric controls held at 3 C, the total uptake at elevated pressure at 3 C was reduced, on an average, 55 times, CO2 respiration was reduced 45 times, and cellular assimilation was reduced 69 times. Rate of total uptake at elevated pressure was found to range from 4.0 X 10(-11) mug/cell per h for leucine to 2.61 X 10(-10) mug/cell per h for an amino acid mixture. Also, the percentage of total uptake at elevated pressures, respired as CO2, increased at the expense of cellular assimilation (ca. 22% increase). Two cellular-associated amino acid pools were detected, a large, loosely bound, outer pool and a small, tightly bound internal pool. The loosely bound outer pool was removed by a change in the pH of the incubation medium. Even though heterotrophic uptake and the outer, cellular-associated pool were markedly reduced at an elevated pressure, the percentage of total uptake calculated for the unincorporated, tightly bound, intracellular pool was 2 to 19 times that obtained for cultures held at 1 atm. The results were interpreted as indicating that bacterial metabolism and biosynthesis in the deep sea are markedly reduced, with a greater proportion of metabolic activity devoted to cellular maintenance. [Abstract/Link to Full Text]

Whitt DD, Demoss RD
Effect of microflora on the free amino acid distribution in various regions of the mouse gastrointestinal tract.
Appl Microbiol. 1975 Oct;30(4):609-15.
The distribution of free amino acids in the contents of various regions of the gastrointestinal tract (stomach, upper small intestine, lower small intestine, cecum, upper colon and lower colon) was studied in germfree and conventionalized mice. Particular emphasis was placed on the conversion of tryptophan to indole as a probe for studying intermicrobial interactions and microbe-host interactions in vivo. Great differences were observed in the free amino acid content of the various regions of the digestive tract in each type of mouse and also in any one region between germfree and conventionalized mice. As would be expected, there were fewer differences in amino acid distribution between the types of mice in both regions of the small intestine. This correlates with a much lower population of microorganisms in these regions. The changes in free amino acid content and distribution produced by microflora are great enough to serve as a good probe for studying the interactions of a limited number of species of microbes in gnotobiotic animals and assign possible specific functions to each species. [Abstract/Link to Full Text]

Oremland RS
Methane production in shallow-water, tropical marine sediments.
Appl Microbiol. 1975 Oct;30(4):602-8.
The in situ production of methane was monitored in several types of tropical benthic communities. A bed of Thalassia testudinum located in Caesar Creek (Florida Keys) exhibited the highest methanogenic activity (initial rates = 1.81 to 1.86 mumol CH4/m2 per h) as compared with another seagrass (Syringodium sp., 0.15 to 0.33 mumol/m2 per h) and two coral reef environments (Hydro-Lab, 0.016 to 0.10 mumol/m2 per h; Curacao, 0.14 to 0.47 mumol/m2 per h). The results suggest that a wide variety of benthic metabolic processes (e.g., photosynthetic oxygen production) influences methane production rates. [Abstract/Link to Full Text]

Wells JM, Payne JA
Toxigenic Aspergillus and Penicillium isolates from weevil-damaged chestnuts.
Appl Microbiol. 1975 Oct;30(4):536-40.
Aspergillus and Penicillium were among the most common genera of fungi isolated on malt-salt agar from weevil-damaged Chinese chestnut kernels (16.8 and 40.7% occurrence, respectively). Chloroform extracts of 21 of 50 Aspergillus isolates and 18 of 50 representative Penicillium isolates, grown for 4 weeks at 21.1 C on artificial medium, were toxic to day-old cockerels. Tweleve of the toxic Aspergillus isolates were identified as A. wentii, eight as A. flavus, and one as A. flavus var. columnaris. Nine of the toxic Penicillium isolates were identified as P. terrestre, three as P. steckii, two each as P. citrinum and P. funiculosum, and one each as P. herquei (Series) and P. roqueforti (Series). Acute diarrhea was associated with the toxicity of A. wentii and muscular tremors with the toxicity of P. terrestre, one isolate of P. steckii, and one of P. funiculosum. [Abstract/Link to Full Text]

Oie SH, Fystro D
Efficacy of the inactivation of bacterial spores in white petrolatum and a hydrophilic ointment by gamma irradiation.
Appl Microbiol. 1975 Oct;30(4):514-8.
To evaluate the possibilities of using gamma irradiation for the sterilization of ointments, the effect of irradiation on spores of Bacillus pumilus and Bacillus sphaericus in dry material and in two different kinds of ointments was studied. The results indicate that for sterilization purposes irradiation was less effective in white petrolatum as compared to irradiation in the dry state. No such protective effect was found in a hydrophilic ointment. Accordingly, the sterilization dose needed for the sterilization of an ointment can be decided upon only after inactivation experiments with suitable test organisms in the actual preparation. [Abstract/Link to Full Text]

Green BL, Clausen E, Litsky W
Comparison of the new millipore HC with conventional membrane filters for the enumeration of fecal coliform bacteria.
Appl Microbiol. 1975 Oct;30(4):697-9.
Fecal coliform recoveries were determined for six types of membrane filters using 65 nonchlorinated water samples. Results showed that the membranes could be ranked in order of decreasing recovery as follows: Millipore HC greater than Gelman greater than Johns-Manville approximately Sartorius greater than Millipore HA greater than Schleicher & Schuell. [Abstract/Link to Full Text]

Sladek KJ, Suslavich RV, Sohn BI, Dawson FW
Optimum membrane structures for growth of coliform and fecal coliform organisms.
Appl Microbiol. 1975 Oct;30(4):685-91.
The purpose of this study was to determine the optimum membrane filter structure and characteristics for recovery of coliform organisms. Additionally, other factors such as sterilization method and membrane composition were examined. Fecal coliform growth tests with varied samples indicated that the most critical factor in recovery was surface pore morphology and not other factors previously suspected. Fecal coliform counts showed a dramatic increase, with increasing surface opening sizes. Membrane structures with surface openings large enough to surround the entrapped bacteria are required for optimum growth of fecal coliform organisms. Maximum fecal coliform recoveries are obtained using membranes composed of mixed esters of cellulose exhibiting a surface opening diameter of 2.4 mum and a retention pore size of 0.7 mum. [Abstract/Link to Full Text]

Fliermans CB, Schmidt EL
Autoradiography and immunofluorescence combined for autecological study of single cell activity with Nitrobacter as a model system.
Appl Microbiol. 1975 Oct;30(4):676-84.
Specific detection of a particular bacterium by immunofluorescence was combined with estimation of its metabolic activity by autoradiography. The nitrifying bacteria Nitrobacter agilis and N. winogradskyi were used as a model system. Nitrobacter were incubated with NaH14CO3 and 14CO2 prior to study. The same preparations made for autoradiograms were stained with fluorescent antibodies specific for the Nitrobacter species. Examination by epifluorescence and transmitted dark-field microscopy revealed Nitrobacter cells with and without associated silver grains. Direct detection and simultaneous evaluation of metabolic activity of Nitrobacter was demonstrated in pure cultures, in a simple mixed culture, and in a natural soil. [Abstract/Link to Full Text]

Thomson LA, Hageage GJ
Evaluation of excitation light sources for incident immunofluorescence microscopy.
Appl Microbiol. 1975 Oct;30(4):616-24.
A variety of fluorescent excitation light sources were compared using a standard fluorescein solution or a bacterial conjugate with immunofluorescent microscopy. Quantitative data were obtained with microscope photometric apparatus. Both the quantitative data and comparative conjugate titering suggest that the 450-W xenon arc excited significantly more fluorescence than did the more commonly used 250-W mercury arc or the 100-W halogen lamp. The conjugate could be diluted 4 to 32 times more using the 450-W xenon. Additional advantages of 450-W xenon excitation include sufficient energy of wave lengths between 470 to 490 mm, thus permitting narrow-band excitation resulting in less autofluorescence and the ability to perform fluorescent-antibody procedures without the darkening of ambient room light. [Abstract/Link to Full Text]

Newman JS, O'Brien RT
Gas chromatographic presumptive test for coliform bacteria in water.
Appl Microbiol. 1975 Oct;30(4):584-8.
A gas chromatographic procedure which shows promise as a presumptive test for coliform bacteria in water is described. Total coliform bacteria concentrations were determined from the incubation times at 37 C required for ethanol to be produced. Fecal coliform densities were determined in a similar manner at 44.5 C. The culture medium was filter sterilized M-9 salts supplemented with 1% lactose, 0.1% Casamino Acids, and 0.1% yeast extract. Best results were obtained when the initial total coliform concentrations were 5 per ml or higher and when fecal coliform concentrations were 50 per ml or higher. Minimum detection times at these concentrations were 9 and 12 h, respectively. [Abstract/Link to Full Text]

Thomason BM, Hebert GA, Cherry WB
Evaluation of a semiautomated system for direct fluorescent antibody detection of salmonellae.
Appl Microbiol. 1975 Oct;30(4):557-64.
A semi-automatic system under development by Aerojet Medical and Biological Systems for the direct fluorescent antibody detection of salmonellae was evaluated with various food, feed, and environmental samples. All samples were simultaneously examined by Automated Bioassay System (ABS), manual direct fluorescent antibody procedures and cultural procedures. The ABS gave satisfactory results with the processed samples. It detected all of the culturally positive powdered egg and candy samples with no false-negative results and gave only 6.6 and 5.3% false-positive rates, respectively. With meatmeal samples the ABS failed to detect one culturally positive specimen that was also positive by manual fluorescent antibody and gave one (1.1%) false-positive result. A high rate of false-negative results was obtained by ABS on unprocessed samples of creek water, poultry, and sausage. Adding another enrichment step to the protocol reduced the false-negative rate considerably but severely increased the false-positive rate. The instruments worked reasonably well, but research is needed to improve enrichment procedures for samples to be processed by the system. [Abstract/Link to Full Text]

Voss JG
Effects of an antibacterial soap on the ecology of aerobic bacterial flora of human skin.
Appl Microbiol. 1975 Oct;30(4):551-6.
The effects of ad lib use of an antibacterial soap containing 1.0% trichlorocarbanilide and 0.5% trifluoromethyldichlorocarbanilide on the bacterial flora of six skin sites of 132 subjects were measured by comparison with the flora of 93 control subjects who avoided the use of topical antibacterials. Each subject was examined once. The test soap produced significant reductions in geometric mean counts of the total aerobic flora on the back, chest, forearm, calf, and foot; counts were also reduced in the axilla, but not to a significant extent. The overall reduction by the test soap on all sites was 62% (P less than 0.001). Neither age nor sex influenced the effect of the soap on the flora. The antibacterial soap also reduced the prevalence of Staphylococcus aureus on the skin, mostly by virtually eliminating it from areas other than the axilla. Partial inhibition of the gram-positive flora was not accompanied by an increase in gram-negative species. The latter were found principally in the axilla; Klebsiella pneumoniae and Enterobacter aerogenes were the species most frequently found. [Abstract/Link to Full Text]

Sharpe AN, Michaud GL
Enumeration of high numbers of bacteria using hydrophobic grid-membrane filters.
Appl Microbiol. 1975 Oct;30(4):519-24.
Printing a wax grid on a conventional membrane filter yields a device functioning as a most probable number apparatus (MPN), used at a single dilution but with a very large number of growth compartments (e.g., 3,650). By restraining the lateral spread and confluence of colonies, the hydrophobic grid-membrane filter (HGMF) allows growth- or colony-forming units (GU) to be resolved at levels far above those which produce an uncountable lawn on a conventional membrane filter. It also eliminates the size variation of normal bacterial colonies. As a result, the HGMF can give more accurate estimates of the concentration of GU. The method by which grid-cell count observations can be used to obtain MPN estimates of the number of GUs is described, and estimates obtained using the MPN method on the HGMF are compared with those resulting from conventional colony count procedures on membrane filters. A linear relation was observed between MPNGU and the number of GUs, at levels up to 30,000 GUs, for pure cultures of bacteria and for samples of natural waters. The HGMF has great potential for reducing the labor required in quantitative microbiology, since it allows, with one filter, enumeration of microorganisms over a very large concentration range and therefore reduces the need to make dilutions. [Abstract/Link to Full Text]

Robern H, Dighton M, Yano Y, Dickie N
Double-antibody radioimmunoassay for staphylococcal enterotoxin C2.
Appl Microbiol. 1975 Oct;30(4):525-9.
A sensitive double-antibody radioimmunoassay for staphylococcal enterotoxin C2 is described. The assay procedure employs anti-rabbit gamma globulin, prepared in goats, to precipitate the antigen-antibody complex of enterotoxin C2 and anti-enterotoxin C2. The test is sensitive to 100 pg of enterotoxin. [Abstract/Link to Full Text]

Kayser WV, Hickman KC, Bond WW, Favero MS, Carson LA
Bacteriological evaluation of an ultra-pure water-distilling system.
Appl Microbiol. 1975 Oct;30(4):704-6.
A prototype distillation and storage system with recycle for producing ultrapure water was monitored for bacteriological contamination during a period of 24 months. Naturally occurring Pseudomonas aeruginosa and P. cepacia were found to grow rapidly to levels of about 10(5)/ml in water taken from the storage reservoir and also in commercially prepared distilled water. The system was found to eliminate bacterial contaminants introduced into the still with the feed water, but the reservoir, once contaminated, remained contaminated during prolonged recycle, After a single treatment with free chlorine, the entire system remained uncontaminated until accidental or purposeful shutdown. [Abstract/Link to Full Text]

Sayler GS, Nelson JD, Justice A, Colwell RR
Distribution and significance of fecal indicator organisms in the Upper Chesapeake Bay.
Appl Microbiol. 1975 Oct;30(4):625-38.
Total viable aerobic, heterotrophic bacteria, total coliforms, fecal coliforms, and fecal streptococci were enumerated in samples collected at five stations located in the Upper Chesapeake Bay, December 1973 through December 1974. Significant levels of pollution indicator organisms were detected at all of the stations sampled. Highest counts were observed in samples collected at the confluence of the Susquehanna River and the Chesapeake Bay. The indicator organisms examined were observed to be quantitatively distributed independently of temperature and salinity. Counts were not found to be correlated with concentration of suspended sediment. However, significant proportions of both the total viable bacteria (53%) and fecal indicator organisms (greater than 80%) were directly associated with suspended sediments. Correlation coefficinets (r) for the indicator organisms examined in this study ranged from r = 0.80 to r = 0.99 for bottom water and suspended sediment, respectively. Prolonged survival of fecal streptococci in most of the sediment samples was observed, with concomitant reduction of the correlation coefficient from r = 0.99, fecal streptocicci to total coliforms in water, to r = 0.01, fecal streptococci to fecal coliforms in sediments. The results of this study compared favorably with fecal coliforms: fecal streptococci ratios for the various sample types. Characterization of organisms beyond the confirmed most-probable-number procedure provided good correlation between bacterial indicator groups. [Abstract/Link to Full Text]

Highsmith AK, Abshire RL
Evaluation of a most-probable-number technique for the enumeration of Pseudomonas aeruginosa.
Appl Microbiol. 1975 Oct;30(4):596-601.
A most-probable-number (MPN) technique was evaluated for detecting and enumerating Pseudomonas aeruginosa in water and wastewater. Both the presumptive and confirmatory media, as described in the 13th edition of Standard Methods for the Examination of Water and Wastewater, as well as modifications of these media were included in evaluations. Various samples of water were tested, namely chlorinated tap water, creek water, and influent to a wastewater treatment plant. Modified media repeatedly gave higher estimated MPNs of P. aeruginosa than media listed in Standard Methods. P. aeruginosa was detected and recovered from all creek water and wastewater samples, but not from tap water samples tested. This organism was determined to be present in as large numbers as the fecal coliforms and in even greater quantities than the fecal streptococci in all samples, whenever MPN estimations were determined from those positive tubes containing the modified confirmatory medium. [Abstract/Link to Full Text]

Wilson DM, Huang LH, Jay E
Survival of Aspergillus flavus and Fusarium moniliforme in high-moisture corn stored under modified atmospheres.
Appl Microbiol. 1975 Oct;30(4):592-5.
Freshly harvested high-moisture corn with 29.4% moisture and corn remoistened to 19.6% moisture were inoculated with Aspergillus flavus Link ex Fr. and stored for 4 weeks at about 27 C in air (0.03% CO2, 21% O2, and 78% N2) and three modified atmospheres: (i) 99.7% N2 and 0.3% O2; (ii) 61.7% CO2, 8.7% O2, and 29.6% N2; and (iii) 13.5% CO2, 0.5% O2, and 84.8% N2. Kernel infections by A. flavus, Fusarium moniliforme (Sheld.) Snyd. et Hans., and other fungi were monitored weekly. The modified-atmosphere treatments delayed deterioration by A. flavus and F. moniliforme, but their growth was not completely stopped. A. flavus survived better in the remoistened than in the freshly harvested corn. F. moniliforme survived in both. A. flavus and F. moniliforme were the dominant fungi in corn removed from the modified atmospheres and exposed to normal air for 1 week. [Abstract/Link to Full Text]


Recent Articles in Bacteriological Reviews

Greenawalt JW, Whiteside TL
Mesosomes: membranous bacterial organelles.
Bacteriol Rev. 1975 Dec;39(4):405-63. [Abstract/Link to Full Text]

Lovett JS
Growth and differentiation of the water mold Blastocladiella emersonii: cytodifferentiation and the role of ribonucleic acid and protein synthesis.
Bacteriol Rev. 1975 Dec;39(4):345-404. [Abstract/Link to Full Text]

Wiseman GM
The hemolysins of Staphylococcus aureus.
Bacteriol Rev. 1975 Dec;39(4):317-44. [Abstract/Link to Full Text]

Cronan JE, Gelmann EP
Physical properties of membrane lipids: biological relevance and regulation.
Bacteriol Rev. 1975 Sep;39(3):232-56. [Abstract/Link to Full Text]

Drlica KA, Kado CI
Crown gall tumors: are bacterial nucleic acids involved?
Bacteriol Rev. 1975 Sep;39(3):186-96. [Abstract/Link to Full Text]

Hemphill HE, Whiteley HR
Bacteriophages of Bacillus subtilis.
Bacteriol Rev. 1975 Sep;39(3):257-315. [Abstract/Link to Full Text]

Rattray JB, Schibeci A, Kidby DK
Lipids of yeasts.
Bacteriol Rev. 1975 Sep;39(3):197-231. [Abstract/Link to Full Text]

Hooks JJ, Gibbs CJ
The foamy viruses.
Bacteriol Rev. 1975 Sep;39(3):169-85. [Abstract/Link to Full Text]

Morita RY
Psychrophilic bacteria.
Bacteriol Rev. 1975 Jun;39(2):144-67. [Abstract/Link to Full Text]

Schwab JH
Suppression of the immune response by microorganisms.
Bacteriol Rev. 1975 Jun;39(2):121-43. [Abstract/Link to Full Text]

Crawford IP
Gene rearrangements in the evolution of the tryptophan synthetic pathway.
Bacteriol Rev. 1975 Jun;39(2):87-120. [Abstract/Link to Full Text]

Lacey RW
Antibiotic resistance plasmids of Staphylococcus aureus and their clinical importance.
Bacteriol Rev. 1975 Mar;39(1):1-32. [Abstract/Link to Full Text]

Clarke CH, Shankel DM
Antimutagenesis in microbial systems.
Bacteriol Rev. 1975 Mar;39(1):33-53. [Abstract/Link to Full Text]

Collier RJ
Diphtheria toxin: mode of action and structure.
Bacteriol Rev. 1975 Mar;39(1):54-85. [Abstract/Link to Full Text]

Collins FM
Vaccines and cell-mediated immunity.
Bacteriol Rev. 1974 Dec;38(4):371-402. [Abstract/Link to Full Text]

MacKenzie JS, Houghton M
Influenza infections during pregnancy: association with congenital malformations and with subsequent neoplasms in children, and potential hazards of live virus vaccines.
Bacteriol Rev. 1974 Dec;38(4):356-70. [Abstract/Link to Full Text]

Docherty JJ, Chopan M
The latent herpes simplex virus.
Bacteriol Rev. 1974 Dec;38(4):337-55. [Abstract/Link to Full Text]

Blumberg PM, Strominger JL
Interaction of penicillin with the bacterial cell: penicillin-binding proteins and penicillin-sensitive enzymes.
Bacteriol Rev. 1974 Sep;38(3):291-335. [Abstract/Link to Full Text]

Lanyi JK
Salt-dependent properties of proteins from extremely halophilic bacteria.
Bacteriol Rev. 1974 Sep;38(3):272-90. [Abstract/Link to Full Text]

McClung LS, Meyer KF
Beginnings of bacteriology in California.
Bacteriol Rev. 1974 Sep;38(3):251-71. [Abstract/Link to Full Text]

Preer JR, Preer LB, Jurand A
Kappa and other endosymbionts in Paramecium aurelia.
Bacteriol Rev. 1974 Jun;38(2):113-63. [Abstract/Link to Full Text]

Hartwell LH
Saccharomyces cerevisiae cell cycle.
Bacteriol Rev. 1974 Jun;38(2):164-98. [Abstract/Link to Full Text]

Slater M, Schaechter M
Control of cell division in bacteria.
Bacteriol Rev. 1974 Jun;38(2):199-221. [Abstract/Link to Full Text]

Grappel SF, Bishop CT, Blank F
Immunology of dermatophytes and dermatophytosis.
Bacteriol Rev. 1974 Jun;38(2):222-50. [Abstract/Link to Full Text]


Aldolase of Lactic Acid Bacteria: a Case History in the Use of an Enzyme as an Evolutionary Marker.
Bacteriol Rev. 1974 Mar;38(1):111.
[This corrects the article on p. 453 in vol. 37.]. [Abstract/Link to Full Text]

Costerton JW, Ingram JM, Cheng KJ
Structure and function of the cell envelope of gram-negative bacteria.
Bacteriol Rev. 1974 Mar;38(1):87-110. [Abstract/Link to Full Text]

Stebbing N
Precursor pools and endogenous control of enzyme synthesis and activity in biosynthetic pathways.
Bacteriol Rev. 1974 Mar;38(1):1-28. [Abstract/Link to Full Text]

Fox EN
M proteins of group A streptococci.
Bacteriol Rev. 1974 Mar;38(1):57-86. [Abstract/Link to Full Text]

Lemke PA, Nash CH
Fungal viruses.
Bacteriol Rev. 1974 Mar;38(1):29-56. [Abstract/Link to Full Text]

Pace NR
Structure and synthesis of the ribosomal ribonucleic acid of prokaryotes.
Bacteriol Rev. 1973 Dec;37(4):562-603. [Abstract/Link to Full Text]


Recent Articles in BMC Immunology

Moro M, Cecconi V, Martinoli C, Dallegno E, Giabbai B, Degano M, Glaichenhaus N, Protti MP, Dellabona P, Casorati G
Generation of functional HLA-DR*1101 tetramers receptive for loading with pathogen- or tumour-derived synthetic peptides.
BMC Immunol. 2005;624.
BACKGROUND: MHC class I-peptide tetramers are currently utilised to characterize CD8+ T cell responses at single cell level. The generation and use of MHC class II tetramers to study antigen-specific CD4+ T cells appears less straightforward. Most MHC class II tetramers are produced with a homogeneously built-in peptide, reducing greatly their flexibility of use. We attempted the generation of "empty" functional HLA-DR*1101 tetramers, receptive for loading with synthetic peptides by incubation. No such reagent is in fact available for this HLA-DR allele, one of the most frequent in the Caucasian population. RESULTS: We compared soluble MHC class II-immunoglobulin fusion proteins (HLA-DR*1101-Ig) with soluble MHC class II protein fused with an optimised Bir site for enzymatic biotynilation (HLA-DR*1101-Bir), both produced in insect cells. The molecules were multimerised by binding fluorochrome-protein A or fluorochrome-streptavidin, respectively. We find that HLA-DR*1101-Bir molecules are superior to the HLA-DR*1101-Ig ones both in biochemical and functional terms. HLA-DR*1101-Bir molecules can be pulsed with at least three different promiscuous peptide epitopes, derived from Tetanus Toxoid, influenza HA and the tumour associated antigen MAGE-3 respectively, to stain specific CD4+ T cells. Both staining temperature and activation state of CD4+ T cells are critical for the binding of peptide-pulsed HLA-DR*1101-Bir to the cognate TCR. CONCLUSION: It is therefore possible to generate a soluble recombinant HLA-DR*1101 backbone that is receptive for loading with different peptides to stain specific CD4+ T cells. As shown for other HLA-DR alleles, we confirm that not all the strategies to produce soluble HLA-DR*1101 multimers are equivalent. [Abstract/Link to Full Text]

Heinemann DE, Peters JH
Follicular dendritic-like cells derived from human monocytes.
BMC Immunol. 2005;623.
BACKGROUND: Follicular dendritic cells (FDCs) play a central role in controlling B-cell response maturation, isotype switching and the maintenance of B-cell memory. These functions are based on prolonged preservation of antigen and its presentation in its native form by FDCs. However, when entrapping entire pathogens, FDCs can turn into dangerous long-term reservoirs that may preserve viruses or prions in highly infectious form.Despite various efforts, the ontogeny of FDCs has remained elusive. They have been proposed to derive either from bone marrow stromal cells, myeloid cells or local mesenchymal precursors. Still, differentiating FDCs from their precursors in vitro may allow addressing many unsolved issues associated with the (patho-) biology of these important antigen-presenting cells. The aim of our study was to demonstrate that FDC-like cells can be deduced from monocytes, and to develop a protocol in order to quantitatively generate them in vitro. RESULTS: Employing highly purified human monocytes as a starter population, low concentrations of Il-4 (25 U/ml) and GM-CSF (3 U/ml) in combination with Dexamethasone (Dex) (0.5 microM) in serum-free medium trigger the differentiation into FDC-like cells. After transient de-novo membrane expression of alkaline phosphatase (AP), such cells highly up-regulate surface expression of complement receptor I (CD35). Co-expression of CD68 confirms the monocytic origin of both, APpos and CD35pos cells. The common leukocyte antigen CD45 is strongly down-regulated. Successive stimulation with TNF-alpha up-regulates adhesion molecules ICAM-1 (CD54) and VCAM (CD106). Importantly, both, APpos as well as APneg FDC-like cells, heterotypically cluster with and emperipolese B cells and exhibit the FDC characteristic ability to entrap functionally preserved antigen for prolonged times. Identical characteristics are found in monocytes which were highly expanded in vitro by higher doses of GM-CSF (25 U/ml) in the absence of Dex and Il-4 before employing the above differentiation cocktail. CONCLUSION: In this work we provide evidence that FDC-like cells can be derived from monocytes in vitro. Monocyte-derived FDC-like cells quantitatively produced offer a broad utility covering basic research as well as clinical application. [Abstract/Link to Full Text]

Khanna AK
Reciprocal role of cyclins and cyclin kinase inhibitor p21WAF1/CIP1 on lymphocyte proliferation, allo-immune activation and inflammation.
BMC Immunol. 2005;622.
BACKGROUND: Immune activation that results due to the aberrant proliferation of lymphocytes leads to inflammation and graft rejection in organ transplant recipients. We hypothesize that the cell cycle control and inflammation are parallel events, inhibition of cellular proliferation by cyclin kinase inhibitor specifically p21 will limit inflammation and prevent allograft rejection. METHODS: We performed in vitro and in vivo studies using lymphocytes, and rat heart transplant model to understand the role of cyclins and p21 on mitogen and allo-induced lymphocyte activation and inflammation. Lymphocyte proliferation was studied by 3H-thymidine uptake assay and mRNA expression was studied RT-PCR. RESULTS: Activation of allo- and mitogen stimulated lymphocytes resulted in increased expression of cyclins, IL-2 and pro-inflammatory cytokines, which was inhibited by cyclosporine. The over-expression of p21 prolonged graft survival in a completely mismatched rat heart transplant model resulted by inhibiting circulating and intra-graft expression of proinflammatory cytokines. CONCLUSION: Cyclins play a significant role in transplant-induced immune activation and p21 over-expression has potential to inhibit T cell activation and inflammation. The results from this study will permit the design of alternate strategies by controlling cell cycle progression to achieve immunosuppression in transplantation. [Abstract/Link to Full Text]

Yin X, Knecht DA, Lynes MA
Metallothionein mediates leukocyte chemotaxis.
BMC Immunol. 2005;621.
BACKGROUND: Metallothionein (MT) is a cysteine-rich, metal-binding protein that can be induced by a variety of agents. Modulation of MT levels has also been shown to alter specific immune functions. We have noticed that the MT genes map close to the chemokines Ccl17 and Cx3cl1. Cysteine motifs that characterize these chemokines are also found in the MT sequence suggesting that MT might also act as a chemotactic factor. RESULTS: In the experiments reported here, we show that immune cells migrate chemotactically in the presence of a gradient of MT. This response can be specifically blocked by two different monoclonal anti-MT antibodies. Exposure of cells to MT also leads to a rapid increase in F-actin content. Incubation of Jurkat T cells with cholera toxin or pertussis toxin completely abrogates the chemotactic response to MT. Thus MT may act via G-protein coupled receptors and through the cyclic AMP signaling pathway to initiate chemotaxis. CONCLUSION: These results suggest that, under inflammatory conditions, metallothionein in the extracellular environment may support the beneficial movement of leukocytes to the site of inflammation. MT may therefore represent a "danger signal"; modifying the character of the immune response when cells sense cellular stress. Elevated metallothionein produced in the context of exposure to environmental toxicants, or as a result of chronic inflammatory disease, may alter the normal chemotactic responses that regulate leukocyte trafficking. Thus, MT synthesis may represent an important factor in immunomodulation that is associated with autoimmune disease and toxicant exposure. [Abstract/Link to Full Text]

Wright KO, Murray DA, Crispe NI, Pierce RH
Quantitative PCR for detection of the OT-1 transgene.
BMC Immunol. 2005;620.
BACKGROUND: Transgenic TCR mice are often used experimentally as a source of T cells of a defined specificity. One of the most widely used transgenic TCR models is the OT-1 transgenic mouse in which the CD8+ T cells express a TCR specific for the SIINFEKL peptide of ovalbumin presented on kb. Although OT-1 CD8+ can be used in a variety of different experimental settings, we principally employ adoptive transfer and peptide-driven expansion of OT-1 cells in order to explore the distribution and fate of these antigen-specific OT-1 T cells. We set out to develop a quantitative PCR assay for OT-1 cells in order to assess the distribution of OT-1 CD8+ T cells in tissues that are either intrinsically difficult to dissociate for flow cytometric analysis or rendered incompatible with flow cytometric analysis through freezing or fixation. RESULTS: We show excellent correlation between flow cytometric assessment of OT-1 cells and OT-1 signal by qPCR assays in cell dilutions as well as in in vivo adoptive transfer experiments. We also demonstrate that qPCR can be performed from archival formalin-fixed paraffin-embedded tissue sections. In addition, the non-quantitative PCR using the OT-1-specific primers without the real-time probe is a valuable tool for OT-1 genotyping, obviating the need for peripheral blood collection and subsequent flow cytometric analysis. CONCLUSION: An OT-1 specific qPCR assay has been developed to quantify adoptively transferred OT-1 cells. OT-1 qPCR to determine cell signal is a valuable adjunct to the standard flow cytometric analysis of OT-1 cell number, particularly in experimental settings where tissue disaggregation is not desirable or in tissues which are not readily disassociated. [Abstract/Link to Full Text]

Ragin MJ, Hu J, Henderson AJ, August A
A role for the Tec family kinase ITK in regulating SEB-induced interleukin-2 production in vivo via c-jun phosphorylation.
BMC Immunol. 2005;619.
BACKGROUND: Exposure to Staphylococcal Enterotoxin B (SEB), a bacterial superantigen secreted by the Gram-positive bacteria Staphyloccocus aureus, results in the expansion and eventual clonal deletion and anergy of Vbeta8+ T cells, as well as massive cytokine release, including Interleukin-2 (IL-2). This IL-2 is rapidly secreted following exposure to SEB and may contribute to the symptoms seen following exposure to this bacterial toxin. The Tec family kinase ITK has been shown to be important for the production of IL-2 by T cells stimulated in vitro and may represent a good target for blocking the production of this cytokine in vivo. In order to determine if ITK represents such a target, mice lacking ITK were analyzed for their response to SEB exposure. RESULTS: It was found that T cells from mice lacking ITK exhibited significantly reduced proliferative responses to SEB exposure in vitro, as well as in vivo. Examination of IL-2 production revealed that ITK null mice produced reduced levels of this cytokine in vitro, and more dramatically, in vivo. In vivo analysis of c-jun phosphorylation, previously shown to be critical for regulating IL-2 production, revealed that this pathway was specifically activated in SEB reactive Vbeta8+ (but not non-reactive Vbeta6+) T cells from WT mice, but not in Vbeta8+ T cells from ITK null mice. However, toxicity analysis indicated that both WT and ITK null animals were similarly affected by SEB exposure. CONCLUSION: These data show that ITK is required for IL-2 production induced by SEB in vivo, and may regulate signals leading IL-2 production, in part by regulating phosphorylation of c-jun. The data also suggest that perturbing T cell activation pathways leading to IL-2 does not necessarily lead to improved responses to SEB toxicity. [Abstract/Link to Full Text]

Fulgenzi A, Dell'Antonio G, Foglieni C, Dal Cin E, Ticozzi P, Franzone JS, Ferrero ME
Inhibition of chemokine expression in rat inflamed paws by systemic use of the antihyperalgesic oxidized ATP.
BMC Immunol. 2005;618.
BACKGROUND: We previously showed that local use of periodate oxidized ATP (oATP, a selective inhibitor of P2X7 receptors for ATP) in rat paw treated with Freund's adjuvant induced a significant reduction of hyperalgesia Herein we investigate the role of oATP, in the rat paws inflamed by carrageenan, which mimics acute inflammation in humans. RESULTS: Local, oral or intravenous administration of a single dose of oATP significantly reduced thermal hyperalgesia in hind paws of rats for 24 hours, and such effect was greater than that induced by diclofenac or indomethacin. Following oATP treatment, the expression of the pro-inflammatory chemokines interferon-gamma-inducible protein-10 (IP-10), mon ocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) within the inflamed tissues markedly decreased on vessels and infiltrated cells. In parallel, the immunohistochemical findings showed an impairment, with respect to the untreated rats, in P2X7 expression, mainly on nerves and vessels close to the site of inflammation. Finally, oATP treatment significantly reduced the presence of infiltrating inflammatory macrophages in the paw tissue. CONCLUSION: Taken together these results clearly show that oATP reduces carrageenan-induced inflammation in rats. [Abstract/Link to Full Text]

Maecker HT, Moon J, Bhatia S, Ghanekar SA, Maino VC, Payne JK, Kuus-Reichel K, Chang JC, Summers A, Clay TM, Morse MA, Lyerly HK, DeLaRosa C, Ankerst DP, Disis ML
Impact of cryopreservation on tetramer, cytokine flow cytometry, and ELISPOT.
BMC Immunol. 2005;617.
BACKGROUND: Cryopreservation of PBMC and/or overnight shipping of samples are required for many clinical trials, despite their potentially adverse effects upon immune monitoring assays such as MHC-peptide tetramer staining, cytokine flow cytometry (CFC), and ELISPOT. In this study, we compared the performance of these assays on leukapheresed PBMC shipped overnight in medium versus cryopreserved PBMC from matched donors. RESULTS: Using CMV pp65 peptide pool stimulation or pp65 HLA-A2 tetramer staining, there was significant correlation between shipped and cryopreserved samples for each assay (p <or= 0.001). The differences in response magnitude between cryopreserved and shipped PBMC specimens were not significant for most antigens and assays. There was significant correlation between CFC and ELISPOT assay using pp65 peptide pool stimulation, in both shipped and cryopreserved samples (p <or= 0.001). Strong correlation was observed between CFC (using HLA-A2-restricted pp65 peptide stimulation) and tetramer staining (p < 0.001). Roughly similar sensitivity and specificity were observed between the three assays and between shipped and cryopreserved samples for each assay. CONCLUSION: We conclude that all three assays show concordant results on shipped versus cryopreserved specimens, when using a peptide-based readout. The assays are also concordant with each other in pair wise comparisons using equivalent antigen systems. [Abstract/Link to Full Text]

Islander U, Hasséus B, Erlandsson MC, Jochems C, Skrtic SM, Lindberg M, Gustafsson JA, Ohlsson C, Carlsten H
Estren promotes androgen phenotypes in primary lymphoid organs and submandibular glands.
BMC Immunol. 2005;616.
BACKGROUND: Estrogens and androgens have extensive effects on the immune system, for example they suppress both T and B lymphopoiesis in thymus and bone marrow. Submandibular glands are sexually dimorphic in rodents, resulting in larger granular convoluted tubules in males compared to females. The aim of the present experiments was to investigate the estrogenic and androgenic effects of 4-estren-3alpha,17beta-diol (estren) on thymus, bone marrow and submandibular glands, and compare the effects to those of 17beta-estradiol (E2) and 5alpha-dihydrotestosterone (DHT), respectively. Estrogen receptors (ERs) were blocked by treatment of mice with the ER-antagonist ICI 182,780; also, knock-out mice lacking one or both ERs were used. RESULTS: As expected, the presence of functional ERs was mandatory for all the effects of E2. Similar to DHT-treatment, estren-treatment resulted in decreased thymus weight, as well as decreased frequency of bone marrow B cells. Treatment with estren or DHT also resulted in a shift in submandibular glands towards an androgen phenotype. All the effects of estren and DHT were independent of ERs. CONCLUSION: Our study is the first to show that estren has similar effects as the androgen DHT on lymphopoiesis in thymus and bone marrow, and on submandibular glands, and that these effects are independent of estrogen receptors. This supports the hypothesis of estren being able to signal through the androgen receptor. [Abstract/Link to Full Text]

Lu D, Yuan XJ, Evans RJ, Pappas AT, Wang H, Su EW, Hamdouchi C, Venkataraman C
Cloning and functional characterization of the rabbit C-C chemokine receptor 2.
BMC Immunol. 2005;615.
BACKGROUND: CC-family chemokine receptor 2 (CCR2) is implicated in the trafficking of blood-borne monocytes to sites of inflammation and is implicated in the pathogenesis of several inflammatory diseases such as rheumatoid arthritis, multiple sclerosis and atherosclerosis. The major challenge in the development of small molecule chemokine receptor antagonists is the lack of cross-species activity to the receptor in the preclinical species. Rabbit models have been widely used to study the role of various inflammatory molecules in the development of inflammatory processes. Therefore, in this study, we report the cloning and characterization of rabbit CCR2. Data regarding the activity of the CCR2 antagonist will provide valuable tools to perform toxicology and efficacy studies in the rabbit model. RESULTS: Sequence alignment indicated that rabbit CCR2 shares 80 % identity to human CCR2b. Tissue distribution indicated that rabbit CCR2 is abundantly expressed in spleen and lung. Recombinant rabbit CCR2 expressed as stable transfectants in U-937 cells binds radiolabeled 125I-mouse JE (murine MCP-1) with a calculated Kd of 0.1 nM. In competition binding assays, binding of radiolabeled mouse JE to rabbit CCR2 is differentially competed by human MCP-1, -2, -3 and -4, but not by RANTES, MIP-1alpha or MIP-1beta. U-937/rabbit CCR2 stable transfectants undergo chemotaxis in response to both human MCP-1 and mouse JE with potencies comparable to those reported for human CCR2b. Finally, TAK-779, a dual CCR2/CCR5 antagonist effectively inhibits the binding of 125I-mouse JE (IC50 = 2.3 nM) to rabbit CCR2 and effectively blocks CCR2-mediated chemotaxis. CONCLUSION: In this study, we report the cloning of rabbit CCR2 and demonstrate that this receptor is a functional chemotactic receptor for MCP-1. [Abstract/Link to Full Text]

Hasan Z, Zaidi I, Jamil B, Khan MA, Kanji A, Hussain R
Elevated ex vivo monocyte chemotactic protein-1 (CCL2) in pulmonary as compared with extra-pulmonary tuberculosis.
BMC Immunol. 2005;614.
BACKGROUND: Tuberculosis causes 3 million deaths annually. The most common site of tuberculosis is pulmonary however; extra-pulmonary forms of the disease also remain prevalent. Restriction of Mycobacterium tuberculosis depends on effective recruitment and subsequent activation of T lymphocytes, mononuclear and polymorphonuclear cells to the site of infection. Tumor necrosis factor (TNF)-alpha is essential for granuloma formation and is a potent activator of monocyte chemotactic protein (MCP-1, CCL2). CCL2 is essential for recruitment of monocytes and T cells and has been shown to play a role in protection against tuberculosis. Interleukin -8 (CXCL8) is a potent activator of neutrophils. Increased levels of CCL2, CXCL8 and TNFalpha are reported in tuberculosis but their significance in different forms of tuberculosis is as yet unclear. We have used an ex vivo assay to investigate differences in immune parameters in patients with either pulmonary or extra-pulmonary tuberculosis. METHODS: Serum levels of CCL2, CXCL8 and TNFalpha were measured in patients with pulmonary tuberculosis (N = 12), extra-pulmonary tuberculosis (N = 8) and BCG-vaccinated healthy volunteers (N = 12). Whole blood cells were stimulated with non-pathogenic Mycobacterium bovis bacille-Calmette Guerin (BCG) vaccine strain or bacterial lipopolysaccharide (LPS) and cyto/chemokines were monitored in supernatants. RESULTS: Circulating serum levels of CXCL8 and TNFalpha were raised in all tuberculosis patients, while CCL2 levels were not. There was no difference in spontaneous cytokine secretion from whole blood cells between patients and controls. M. bovis BCG-induced ex vivo CCL2 secretion was significantly greater in pulmonary as compared with both extra-pulmonary tuberculosis patients and endemic controls. In response to LPS stimulation, patients with pulmonary tuberculosis showed increased CCL2 and TNFalpha responses as compared with the extra-pulmonary group. BCG-, and LPS-induced CXCL8 secretion was comparable between patients and controls. CONCLUSION: CCL2 is activated by TNFalpha and is essential for recruitment of monocytes and T cells to the site of mycobacterial infection. Increased CCL2 activation in pulmonary tuberculosis may result in a stronger cellular response as compared with extra-pulmonary tuberculosis patients, and this may contribute to the localization of infection to the pulmonary site. [Abstract/Link to Full Text]

Maecker HT, Rinfret A, D'Souza P, Darden J, Roig E, Landry C, Hayes P, Birungi J, Anzala O, Garcia M, Harari A, Frank I, Baydo R, Baker M, Holbrook J, Ottinger J, Lamoreaux L, Epling CL, Sinclair E, Suni MA, Punt K, Calarota S, El-Bahi S, Alter G, Maila H, Kuta E, Cox J, Gray C, Altfeld M, Nougarede N, Boyer J, Tussey L, Tobery T, Bredt B, Roederer M, Koup R, Maino VC, Weinhold K, Pantaleo G, Gilmour J, Horton H, Sekaly RP
Standardization of cytokine flow cytometry assays.
BMC Immunol. 2005;613.
BACKGROUND: Cytokine flow cytometry (CFC) or intracellular cytokine staining (ICS) can quantitate antigen-specific T cell responses in settings such as experimental vaccination. Standardization of ICS among laboratories performing vaccine studies would provide a common platform by which to compare the immunogenicity of different vaccine candidates across multiple international organizations conducting clinical trials. As such, a study was carried out among several laboratories involved in HIV clinical trials, to define the inter-lab precision of ICS using various sample types, and using a common protocol for each experiment (see additional files online). RESULTS: Three sample types (activated, fixed, and frozen whole blood; fresh whole blood; and cryopreserved PBMC) were shipped to various sites, where ICS assays using cytomegalovirus (CMV) pp65 peptide mix or control antigens were performed in parallel in 96-well plates. For one experiment, antigens and antibody cocktails were lyophilised into 96-well plates to simplify and standardize the assay setup. Results ((CD4+)cytokine+ cells and (CD8+)cytokine+ cells) were determined by each site. Raw data were also sent to a central site for batch analysis with a dynamic gating template. Mean inter-laboratory coefficient of variation (C.V.) ranged from 17-44% depending upon the sample type and analysis method. Cryopreserved peripheral blood mononuclear cells (PBMC) yielded lower inter-lab C.V.'s than whole blood. Centralized analysis (using a dynamic gating template) reduced the inter-lab C.V. by 5-20%, depending upon the experiment. The inter-lab C.V. was lowest (18-24%) for samples with a mean of > 0.5% IFNgamma + T cells, and highest (57-82%) for samples with a mean of < 0.1% IFNgamma + cells. CONCLUSION: ICS assays can be performed by multiple laboratories using a common protocol with good inter-laboratory precision, which improves as the frequency of responding cells increases. Cryopreserved PBMC may yield slightly more consistent results than shipped whole blood. Analysis, particularly gating, is a significant source of variability, and can be reduced by centralized analysis and/or use of a standardized dynamic gating template. Use of pre-aliquoted lyophilized reagents for stimulation and staining can provide further standardization to these assays. [Abstract/Link to Full Text]

Dreyfus DH, Nagasawa M, Gelfand EW, Ghoda LY
Modulation of p53 activity by IkappaBalpha: evidence suggesting a common phylogeny between NF-kappaB and p53 transcription factors.
BMC Immunol. 2005;612.
BACKGROUND: In this work we present evidence that the p53 tumor suppressor protein and NF-kappaB transcription factors could be related through common descent from a family of ancestral transcription factors regulating cellular proliferation and apoptosis. P53 is a homotetrameric transcription factor known to interact with the ankyrin protein 53BP2 (a fragment of the ASPP2 protein). NF-kappaB is also regulated by ankyrin proteins, the prototype of which is the IkappaB family. The DNA binding sequences of the two transcription factors are similar, sharing 8 out of 10 nucleotides. Interactions between the two proteins, both direct and indirect, have been noted previously and the two proteins play central roles in the control of proliferation and apoptosis. RESULTS: Using previously published structure data, we noted a significant degree of structural alignment between p53 and NF-kappaB p65. We also determined that IkappaBalpha and p53 bind in vitro through a specific interaction in part involving the DNA binding region of p53, or a region proximal to it, and the amino terminus of IkappaBalpha independently or cooperatively with the ankyrin 3 domain of IkappaBalpha In cotransfection experiments, kappaBalpha could significantly inhibit the transcriptional activity of p53. Inhibition of p53-mediated transcription was increased by deletion of the ankyrin 2, 4, or 5 domains of IkappaBalpha Co-precipitation experiments using the stably transfected ankyrin 5 deletion mutant of kappaBalpha and endogenous wild-type p53 further support the hypothesis that p53 and IkappaBalpha can physically interact in vivo. CONCLUSION: The aggregate results obtained using bacterially produced IkappaBalpha and p53 as well as reticulocyte lysate produced proteins suggest a correlation between in vitro co-precipitation in at least one of the systems and in vivo p53 inhibitory activity. These observations argue for a mechanism involving direct binding of IkappaBalpha to p53 in the inhibition of p53 transcriptional activity, analogous to the inhibition of NF-kappaB by kappaBalpha and p53 by 53BP2/ASPP2. These data furthermore suggest a role for ankyrin proteins in the regulation of p53 activity. Taken together, the NFkappaB and p53 proteins share similarities in structure, DNA binding sites and binding and regulation by ankyrin proteins in support of our hypothesis that the two proteins share common descent from an ancestral transcriptional factor. [Abstract/Link to Full Text]

Nygaard UC, Aase A, Løvik M
The allergy adjuvant effect of particles - genetic factors influence antibody and cytokine responses.
BMC Immunol. 2005;611.
BACKGROUND: There is increasing epidemiological and experimental evidence for an aggravating effect of particulate air pollution on asthma and allergic symptoms and, to a lesser extent, on allergic sensitization. Genetic factors appear to influence not only the magnitude, but also the quality of the adjuvant effect of particles with respect to allergen-specific IgE (Th2-associated) and IgG2a (Th1-associated) responses. In the present study, we aimed to investigate how the genetic background influences the responses to the allergen and particles alone and in combination. We examined how polystyrene particles (PSP) affected the IgE and IgG2a responses against the model allergen ovalbumin (OVA), after subcutaneous injection into the footpad of BALB/cA, BALB/cJ, NIH and C3H/HeN mice, Further, ex vivo IL-4, IFN-gamma and IL-10 cytokine secretion by Con A-stimulated cells from the draining popliteal lymph node (PLN) five days after injection of OVA and PSP separately or in combination was determined. RESULTS: PSP injected with OVA increased the levels of OVA-specific IgE antibodies in all strains examined. In contrast, the IgG2a levels were significantly increased only in NIH and C3H/HeN mice. PSP in the presence of OVA increased cell numbers and IL-4, IL-10 and IFN-gamma levels in BALB/cA, NIH and C3H/HeN mice, with the exception of IFN-gamma in NIH mice. However, each mouse strain had their unique pattern of response to OVA+PSP, OVA and PSP, and also their unique background cytokine response (i.e. the cytokine response in cells from mice injected with buffer only). CONCLUSION: Genetic factors (i.e. the strain of mice) influenced the susceptibility to the adjuvant effect of PSP on both secondary antibody responses and primary cellular responses in the lymph node, as well as the cellular responses to both OVA and PSP given separately. Interestingly, PSP alone induced cytokine responses in the lymph node in some of the mouse strains. Furthermore, we found that the ex vivo cytokine patterns did not predict the in vivo Th2- and Th1-associated antibody response patterns in the different mouse strains. The results indicate that insoluble particles act by increasing the inherent response to the allergen, and that the genetic background may determine whether an additional Th1-associated component is added to the response. [Abstract/Link to Full Text]

Mayorov VI, Rogozin IB, Adkison LR, Frahm C, Kunkel TA, Pavlov YI
Expression of human AID in yeast induces mutations in context similar to the context of somatic hypermutation at G-C pairs in immunoglobulin genes.
BMC Immunol. 2005;6(1):10.
BACKGROUND: Antibody genes are diversified by somatic hypermutation (SHM), gene conversion and class-switch recombination. All three processes are initiated by the activation-induced deaminase (AID). According to a DNA deamination model of SHM, AID converts cytosine to uracil in DNA sequences. The initial deamination of cytosine leads to mutation and recombination in pathways involving replication, DNA mismatch repair and possibly base excision repair. The DNA sequence context of mutation hotspots at G-C pairs during SHM is DGYW/WRCH (G-C is a hotspot position, R = A/G, Y = T/C, W = A/T, D = A/G/T). RESULTS: To investigate the mechanisms of AID-induced mutagenesis in a model system, we studied the genetic consequences of AID expression in yeast. We constructed a yeast vector with an artificially synthesized human AID gene insert using codons common to highly expressed yeast genes. We found that expression of the artificial hAIDSc gene was moderately mutagenic in a wild-type strain and highly mutagenic in an ung1 uracil-DNA glycosylase-deficient strain. A majority of mutations were at G-C pairs. In the ung1 strain, C-G to T-A transitions were found almost exclusively, while a mixture of transitions with 12% transversions was characteristic in the wild-type strain. In the ung1 strain mutations that could have originated from deamination of the transcribed stand were found more frequently. In the wild-type strain, the strand bias was reversed. DGYW/WRCH motifs were preferential sites of mutations. CONCLUSION: The results are consistent with the hypothesis that AID-mediated deamination of DNA is a major cause of mutations at G-C base pairs in immunoglobulin genes during SHM. The sequence contexts of mutations in yeast induced by AID and those of somatic mutations at G-C pairs in immunoglobulin genes are significantly similar. This indicates that the intrinsic substrate specificity of AID itself is a primary determinant of mutational hotspots at G-C base pairs during SHM. [Abstract/Link to Full Text]

Kersten C, Sivertsen EA, Hystad ME, Forfang L, Smeland EB, Myklebust JH
BMP-6 inhibits growth of mature human B cells; induction of Smad phosphorylation and upregulation of Id1.
BMC Immunol. 2005;6(1):9.
BACKGROUND: Bone morphogenetic proteins (BMPs) belong to the TGF-beta superfamily and are secreted proteins with pleiotropic roles in many different cell types. A potential role of BMP-6 in the immune system has been implied by various studies of malignant and rheumatoid diseases. In the present study, we explored the role of BMP-6 in normal human peripheral blood B cells. RESULTS: The B cells were found to express BMP type I and type II receptors and BMP-6 rapidly induced phosphorylation of Smad1/5/8. Furthermore, Smad-phosphorylation was followed by upregulation of Id1 mRNA and Id1 protein, whereas Id2 and Id3 expression was not affected. Furthermore, we found that BMP-6 had an antiproliferative effect both in naive (CD19+CD27-) and memory B cells (CD19+CD27+) stimulated with anti-IgM alone or the combined action of anti-IgM and CD40L. Additionally, BMP-6 induced cell death in activated memory B cells. Importantly, the antiproliferative effect of BMP-6 in B-cells was completely neutralized by the natural antagonist, noggin. Furthermore, B cells were demonstrated to upregulate BMP-6 mRNA upon stimulation with anti-IgM. CONCLUSION: In mature human B cells, BMP-6 inhibited cell growth, and rapidly induced phosphorylation of Smad1/5/8 followed by an upregulation of Id1. [Abstract/Link to Full Text]

Ferguson AR, Corley RB
Accumulation of marginal zone B cells and accelerated loss of follicular dendritic cells in NF-kappaB p50-deficient mice.
BMC Immunol. 2005;6(1):8.
BACKGROUND: Marginal zone (MZ) B cells play important roles in the early phases of humoral immune responses. In addition to possessing an inherent capacity to rapidly differentiate into antibody secreting cells, MZ B cells also help to regulate the fate of both T-independent and T-dependent blood-borne antigens in the spleen. For T-dependent antigens, MZ B cells bind IgM-antigen complexes in a complement-dependent manner. Once MZ B cells bind IgM-containing immune complexes (IgM-IC), they transport them into B cell follicles for deposition onto follicular dendritic cells (FDCs), an important component of secreted IgM's ability to enhance adaptive immune responses. To further define the requirement for MZ B cells in IgM-IC deposition, mice deficient in the NF-kappaB protein p50, which have been reported to lack MZ B cells, were analyzed for their ability to trap IgM-IC onto FDCs. RESULTS: Mice (2 months of age) deficient in p50 (p50-/-) had small numbers of MZ B cells, as determined by cell surface phenotype and localization in the splenic MZ. These cells bound high levels of IgM-IC both in vivo and in vitro. Subsequent to the binding of IgM-IC by the MZ B cells in p50-/- mice, small amounts of IgM-IC were found localized on FDCs, suggesting that the MZ B cells retained their ability to transport these complexes into splenic follicles. Strikingly, MZ B cells accumulated with age in p50-/- mice. By 6 months of age, p50-/- mice contained normal numbers of these cells as defined by CD21/CD23 profile and high level expression of CD1d, CD9, and IgM, and by their positioning around the marginal sinus. However, FDCs from these older p50-/- mice exhibited a reduced capacity to trap IgM-IC and retain complement components. CONCLUSION: These results demonstrate that while the p50 component of the NF-kappaB transcription complex plays an important role in the early development of MZ B cells, MZ B cells can develop and accumulate in mice lacking this protein. These results highlight the interface between genetic deficiencies and age, and suggest that different transcription factors may play distinct roles in the development and maintenance of cell populations at different ages. [Abstract/Link to Full Text]

Zimmermann N, Colyer JL, Koch LE, Rothenberg ME
Analysis of the CCR3 promoter reveals a regulatory region in exon 1 that binds GATA-1.
BMC Immunol. 2005;6(1):7.
BACKGROUND: CC Chemokine Receptor 3 (CCR3), the major chemokine receptor expressed on eosinophils, binds promiscuously to several ligands including eotaxins 1, 2, and 3. Even though the only cells that consistently accumulate following eotaxin administration in vivo are myeloid cells (primarily eosinophils), other cell types have recently been shown to express CCR3. It is therefore important to elucidate the molecular mechanisms regulating receptor expression. RESULTS: In order to define regions responsible for CCR3 transcription, a DNAse hypersensitive site was identified in the vicinity of exon 1. Coupled with our previous data implicating exon 1 in CCR3 transcription, we hypothesized that transcription factors bind to exon-1. Electrophoretic mobility shift analysis revealed that nuclear proteins in eosinophilic cells bound to exon 1. Furthermore, antibody interference and mutation studies demonstrated GATA-1 binding to exon 1. In order to test the 1.6-kb CCR3 promoter element (that includes exon 1) for in vivo function, this region was used to generate transgenic mice that expressed a reporter protein. Strong transgene expression was achieved, with the pattern of expression suggesting a broad acting promoter. CONCLUSION: The transcription factor GATA-1 binds to CCR3 exon 1. The 1.6-kb CCR3 promoter element, that includes exon 1, is a strong promoter in vivo. [Abstract/Link to Full Text]

Pablos JL, Santiago B, Tsay D, Singer MS, Palao G, Galindo M, Rosen SD
A HEV-restricted sulfotransferase is expressed in rheumatoid arthritis synovium and is induced by lymphotoxin-alpha/beta and TNF-alpha in cultured endothelial cells.
BMC Immunol. 2005;6(1):6.
BACKGROUND: The recruitment of lymphocytes to secondary lymphoid organs relies on interactions of circulating cells with high endothelial venules (HEV). HEV are exclusive to these organs under physiological conditions, but they can develop in chronically-inflamed tissues. The interaction of L-selectin on lymphocytes with sulfated glycoprotein ligands on HEV results in lymphocyte rolling, which represents the initial step in lymphocyte homing. HEV expression of GlcNAc6ST-2 (also known as HEC-GlcNAc6ST, GST-3, LSST or CHST4), an HEV-restricted sulfotransferase, is essential for the elaboration of L-selectin functional ligands as well as a critical epitope recognized by MECA-79 mAb. RESULTS: We examined the expression of GlcNAc6ST-2 in relationship to the MECA-79 epitope in rheumatoid arthritis (RA) synovial vessels. Expression of GlcNAc6ST-2 was specific to RA synovial tissues as compared to osteoarthritis synovial tissues and localized to endothelial cells of HEV-like vessels and small flat-walled vessels. Double MECA-79 and GlcNAc6ST-2 staining showed colocalization of the MECA-79 epitope and GlcNAc6ST-2. We further found that both TNF-alpha and lymphotoxin-alphabeta induced GlcNAc6ST-2 mRNA and protein in cultured human umbilical vein endothelial cells. CONCLUSION: These observations demonstrate that GlcNAc6ST-2 is induced in RA vessels and provide potential cytokine pathways for its induction. GlcNAc6ST-2 is a novel marker of activated vessels within RA ectopic lymphoid aggregates. This enzyme represents a potential therapeutic target for RA. [Abstract/Link to Full Text]

Boeuf P, Vigan-Womas I, Jublot D, Loizon S, Barale JC, Akanmori BD, Mercereau-Puijalon O, Behr C
CyProQuant-PCR: a real time RT-PCR technique for profiling human cytokines, based on external RNA standards, readily automatable for clinical use.
BMC Immunol. 2005;6(1):5.
BACKGROUND: Real-time PCR is becoming a common tool for detecting and quantifying expression profiling of selected genes. Cytokines mRNA quantification is widely used in immunological research to dissect the early steps of immune responses or pathophysiological pathways. It is also growing to be of clinical relevancy to immuno-monitoring and evaluation of the disease status of patients. The techniques currently used for "absolute quantification" of cytokine mRNA are based on a DNA standard curve and do not take into account the critical impact of RT efficiency. RESULTS: To overcome this pitfall, we designed a strategy using external RNA as standard in the RT-PCR. Use of synthetic RNA standards, by comparison with the corresponding DNA standard, showed significant variations in the yield of retro-transcription depending the target amplified and the experiment. We then developed primers to be used under one single experimental condition for the specific amplification of human IL-1beta, IL-4, IL-10, IL-12p40, IL-13, IL-15, IL-18, IFN-gamma, MIF, TGF-beta1 and TNF-alpha mRNA. We showed that the beta-2 microglobulin (beta2-MG) gene was suitable for data normalisation since the level of beta2-MG transcripts in naive PBMC varied less than 5 times between individuals and was not affected by LPS or PHA stimulation. The technique, we named CyProQuant-PCR (Cytokine Profiling Quantitative PCR) was validated using a kinetic measurement of cytokine transcripts under in vitro stimulation of human PBMC by lipopolysaccharide (LPS) or Staphylococcus aureus strain Cowan (SAC). Results obtained show that CyProQuant-PCR is powerful enough to precociously detect slight cytokine induction. Finally, having demonstrated the reproducibility of the method, it was applied to malaria patients and asymptomatic controls for the quantification of TGF-beta1 transcripts and showed an increased capacity of cells from malaria patients to accumulate TGF-beta1 mRNA in response to LPS. CONCLUSION: The real-time RT-PCR technique based on a RNA standard curve, CyProQuant-PCR, outlined here, allows for a genuine absolute quantification and a simultaneous analysis of a large panel of human cytokine mRNA. It represents a potent and attractive tool for immunomonitoring, lending itself readily to automation and with a high throughput. This opens the possibility of an easy and reliable cytokine profiling for clinical applications. [Abstract/Link to Full Text]

Linehan SA
The mannose receptor is expressed by subsets of APC in non-lymphoid organs.
BMC Immunol. 2005;6(1):4.
BACKGROUND: The mannose receptor (MR) is an endocytic receptor of Mphi and endothelial cell subsets whose natural ligands include both self glycoproteins and microbial glycans. It is also expressed by immature cultured dendritic cells (DC), where it mediates high efficiency uptake of glycosylated antigens, yet its role in antigen handling in vivo is unknown. Knowledge of which APC subsets express MR will assist the design of experiments to address its immunological functions. Here the expression of MR by MHC class II positive APC in non-lymphoid organs of the mouse is described. RESULTS: MR positive APC were identified in several peripheral organs: skin, liver, cardiac and skeletal muscle and tongue. MR positive cells in salivary gland, thyroid and pancreas coexpressed MHC class II and the myeloid markers macrosialin and sialoadhesin, but not the dendritic cell markers CD11c or DEC-205. MR and MHC class II colocalised in confocal microscope images, implying that antigen capture may be the primary role of MR in these cells. Distinct ligands of MR were found in salivary gland and pancreas tissue lysates that are candidate physiological ligands of MR positive APC in these organs. CONCLUSIONS: The tissue and subcellular distribution of MR suggest it is appropriately located to serve as a high efficiency antigen uptake receptor of APC. [Abstract/Link to Full Text]

Kim JR, Lim HW, Kang SG, Hillsamer P, Kim CH
Human CD57+ germinal center-T cells are the major helpers for GC-B cells and induce class switch recombination.
BMC Immunol. 2005;6(1):3.
BACKGROUND: The function of CD57+ CD4+ T cells, constituting a major subset of germinal center T (GC-Th) cells in human lymphoid tissues, has been unclear. There have been contradictory reports regarding the B cell helping function of CD57+ GC-Th cells in production of immunoglobulin (Ig). Furthermore, the cytokine and co-stimulation requirement for their helper activity remains largely unknown. To clarify and gain more insight into their function in helping B cells, we systematically investigated the capacity of human tonsil CD57+ GC-Th cells in inducing B cell Ig synthesis. RESULTS: We demonstrated that CD57+ GC-Th cells are highly efficient in helping B cell production of all four subsets of Ig (IgM, IgG, IgA and IgE) compared to other T-helper cells located in germinal centers or interfollicular areas. CD57+ GC-Th cells were particularly more efficient than other T cells in helping GC-B cells but not naive B cells. CD57+ GC-Th cells induced the expression of activation-induced cytosine deaminase (AID) and class switch recombination in developing B cells. IgG1-3 and IgA1 were the major Ig isotypes induced by CD57+ GC-Th cells. CD40L, but not IL-4, IL-10 and IFN-gamma, was critical in CD57+ GC-Th cell-driven B cell production of Ig. However, IL-10, when added exogenously, significantly enhanced the helper activity of CD57+ GC-Th cells, while TGF-beta1 completely and IFN-gamma partially suppressed the CD57+ GC-Th cell-driven Ig production. CONCLUSIONS: CD57+CD4+ T cells in the germinal centers of human lymphoid tissues are the major T helper cell subset for GC-B cells in Ig synthesis. Their helper activity is consistent with their capacity to induce AID and class switch recombination, and can be regulated by CD40L, IL-4, IL-10 and TGF-beta. [Abstract/Link to Full Text]

Reghunathan R, Jayapal M, Hsu LY, Chng HH, Tai D, Leung BP, Melendez AJ
Expression profile of immune response genes in patients with Severe Acute Respiratory Syndrome.
BMC Immunol. 2005;62.
BACKGROUND: Severe acute respiratory syndrome (SARS) emerged in later February 2003, as a new epidemic form of life-threatening infection caused by a novel coronavirus. However, the immune-pathogenesis of SARS is poorly understood. To understand the host response to this pathogen, we investigated the gene expression profiles of peripheral blood mononuclear cells (PBMCs) derived from SARS patients, and compared with healthy controls. RESULTS: The number of differentially expressed genes was found to be 186 under stringent filtering criteria of microarray data analysis. Several genes were highly up-regulated in patients with SARS, such as, the genes coding for Lactoferrin, S100A9 and Lipocalin 2. The real-time PCR method verified the results of the gene array analysis and showed that those genes that were up-regulated as determined by microarray analysis were also found to be comparatively up-regulated by real-time PCR analysis. CONCLUSIONS: This differential gene expression profiling of PBMCs from patients with SARS strongly suggests that the response of SARS affected patients seems to be mainly an innate inflammatory response, rather than a specific immune response against a viral infection, as we observed a complete lack of cytokine genes usually triggered during a viral infection. Our study shows for the first time how the immune system responds to the SARS infection, and opens new possibilities for designing new diagnostics and treatments for this new life-threatening disease. [Abstract/Link to Full Text]

Saxinger C, Conrads TP, Goldstein DJ, Veenstra TD
Fully automated synthesis of (phospho)peptide arrays in microtiter plate wells provides efficient access to protein tyrosine kinase characterization.
BMC Immunol. 2005;6(1):1.
BACKGROUND: Synthetic peptides have played a useful role in studies of protein kinase substrates and interaction domains. Synthetic peptide arrays and libraries, in particular, have accelerated the process. Several factors have hindered or limited the applicability of various techniques, such as the need for deconvolution of combinatorial libraries, the inability or impracticality of achieving full automation using two-dimensional or pin solid phases, the lack of convenient interfacing with standard analytical platforms, or the difficulty of compartmentalization of a planar surface when contact between assay components needs to be avoided. This paper describes a process for synthesis of peptides and phosphopeptides on microtiter plate wells that overcomes previous limitations and demonstrates utility in determination of the epitope of an autophosphorylation site phospho-motif antibody and utility in substrate utilization assays of the protein tyrosine kinase, p60c-src. RESULTS: The overall reproducibility of phospho-peptide synthesis and multiplexed EGF receptor (EGFR) autophosphorylation site (pY1173) antibody ELISA (9H2) was within 5.5 to 8.0%. Mass spectrometric analyses of the released (phospho)peptides showed homogeneous peaks of the expected molecular weights. An overlapping peptide array of the complete EGFR cytoplasmic sequence revealed a high redundancy of 9H2 reactive sites. The eight reactive phospopeptides were structurally related and interestingly, the most conserved antibody reactive peptide motif coincided with a subset of other known EGFR autophosphorylation and SH2 binding motifs and an EGFR optimal substrate motif. Finally, peptides based on known substrate specificities of c-src and related enzymes were synthesized in microtiter plate array format and were phosphorylated by c-Src with the predicted specificities. The level of phosphorylation was proportional to c-Src concentration with sensitivities below 0.1 Units of enzyme. CONCLUSIONS: The ability of this method to interface with various robotics and instrumentation is highly flexible since the microtiter plate is an industry standard. It is highly scalable by increasing the surface area within the well or the number of wells and does not require specialized robotics. The microtiter plate array system is well suited to the study of protein kinase substrates, antigens, binding molecules, and inhibitors since these all can be quantitatively studied at a single uniform, reproducible interface. [Abstract/Link to Full Text]

Pruett SB, Padgett EL
Thymus-derived glucocorticoids are insufficient for normal thymus homeostasis in the adult mouse.
BMC Immunol. 2004 Nov 2;524.
BACKGROUND: It is unclear if thymus-derived glucocorticoids reach sufficient local concentrations to support normal thymus homeostasis, or if adrenal-derived glucocorticoids from the circulation are required. Modern approaches to this issue (transgenic mice that under or over express glucocorticoid receptor in the thymus) have yielded irreconcilably contradictory results, suggesting fundamental problems with one or more the transgenic mouse strains used. In the present study, a more direct approach was used, in which mice were adrenalectomized with or without restoration of circulating corticosterone using timed release pellets. Reversal of the increased number of thymocytes caused by adrenalectomy following restoration of physiological corticosterone concentrations would indicate that corticosterone is the major adrenal product involved in thymic homeostasis. RESULTS: A clear relationship was observed between systemic corticosterone concentration, thymus cell number, and percentage of apoptotic thymocytes. Physiological concentrations of corticosterone in adrenalectomized mice restored thymus cell number to normal values and revealed differential sensitivity of thymocyte subpopulations to physiological and stress-inducible corticosterone concentrations. CONCLUSION: This indicates that thymus-derived glucocorticoids are not sufficient to maintain normal levels of death by neglect in the thymus, but that apoptosis and possibly other mechanisms induced by physiological, non stress-induced levels of adrenal-derived corticosterone are responsible for keeping the total number of thymocytes within the normal range. [Abstract/Link to Full Text]

Davenport BJ, Willis DG, Prescott J, Farrell RM, Coons TA, Schountz T
Generation of competent bone marrow-derived antigen presenting cells from the deer mouse (Peromyscus maniculatus).
BMC Immunol. 2004 Sep 30;523.
BACKGROUND: Human infections with Sin Nombre virus (SNV) and related New World hantaviruses often lead to hantavirus cardiopulmonary syndrome (HCPS), a sometimes fatal illness. Lungs of patients who die from HCPS exhibit cytokine-producing mononuclear infiltrates and pronounced pulmonary inflammation. Deer mice (Peromyscus maniculatus) are the principal natural hosts of SNV, in which the virus establishes life-long persistence without conspicuous pathology. Little is known about the mechanisms SNV employs to evade the immune response of deer mice, and experimental examination of this question has been difficult because of a lack of methodologies for examining such responses during infection. One such deficiency is our inability to characterize T cell responses because susceptible syngeneic deer mice are not available. RESULTS: To solve this problem, we have developed an in vitro method of expanding and generating competent antigen presenting cells (APC) from deer mouse bone marrow using commercially-available house mouse (Mus musculus) granulocyte-macrophage colony stimulating factor. These cells are capable of processing and presenting soluble protein to antigen-specific autologous helper T cells in vitro. Inclusion of antigen-specific deer mouse antibody augments T cell stimulation, presumably through Fc receptor-mediated endocytosis. CONCLUSIONS: The use of these APC has allowed us to dramatically expand deer mouse helper T cells in culture and should permit extensive characterization of T cell epitopes. Considering the evolutionary divergence between deer mice and house mice, it is probable that this method will be useful to other investigators using unconventional models of rodent-borne diseases. [Abstract/Link to Full Text]

Ferrero E, Orciani M, Vacca P, Ortolan E, Crovella S, Titti F, Saccucci F, Malavasi F
Characterization and phylogenetic epitope mapping of CD38 ADPR cyclase in the cynomolgus macaque.
BMC Immunol. 2004 Sep 21;521.
BACKGROUND: The CD38 transmembrane glycoprotein is an ADP-ribosyl cyclase that moonlights as a receptor in cells of the immune system. Both functions are independently implicated in numerous areas related to human health. This study originated from an inherent interest in studying CD38 in the cynomolgus monkey (Macaca fascicularis), a species closely related to humans that also represents a cogent animal model for the biomedical analysis of CD38. RESULTS: A cDNA was isolated from cynomolgus macaque peripheral blood leukocytes and is predicted to encode a type II membrane protein of 301 amino acids with 92% identity to human CD38. Both RT-PCR-mediated cDNA cloning and genomic DNA PCR surveying were possible with heterologous human CD38 primers, demonstrating the striking conservation of CD38 in these primates. Transfection of the cDNA coincided with: (i) surface expression of cynomolgus macaque CD38 by immunofluorescence; (ii) detection of approximately 42 and 84 kDa proteins by Western blot and (iii) the appearance of ecto-enzymatic activity. Monoclonal antibodies were raised against the cynomolgus CD38 ectodomain and were either species-specific or cross-reactive with human CD38, in which case they were directed against a common disulfide-requiring conformational epitope that was mapped to the C-terminal disulfide loop. CONCLUSION: This multi-faceted characterization of CD38 from cynomolgus macaque demonstrates its high genetic and biochemical similarities with human CD38 while the immunological comparison adds new insights into the dominant epitopes of the primate CD38 ectodomain. These results open new prospects for the biomedical and pharmacological investigations of this receptor-enzyme. [Abstract/Link to Full Text]

Chi DS, Fitzgerald SM, Pitts S, Cantor K, King E, Lee SA, Huang SK, Krishnaswamy G
MAPK-dependent regulation of IL-1- and beta-adrenoreceptor-induced inflammatory cytokine production from mast cells: implications for the stress response.
BMC Immunol. 2004 Sep 21;522.
BACKGROUND: Catecholamines, such as epinephrine, are elaborated in stress responses, and mediate vasoconstriction to cause elevation in systemic vascular resistance and blood pressure. Our previous study has shown that IL-1 can induce mast cells to produce proinflammatory cytokines which are involved in atherogenesis. The aim of this study was to determine the effects of epinephrine on IL-1-induced proatherogenic cytokine production from mast cells. RESULTS: Two ml of HMC-1 (0.75 x 106 cells/ml) were cultured with epinephrine (1 x 10-5 M) in the presence or absence of IL-1 beta (10 ng/ml) for 24 hrs. HMC-1 cultured alone produced none to trace amounts of IL-6, IL-8, and IL-13. IL-1 beta significantly induced production of these cytokines in HMC-1, while epinephrine alone did not. However, IL-6, IL-8, and IL-13 production induced by IL-1 beta were significantly enhanced by addition of epinephrine. The enhancing effect appears to involve NF-kappa B and p38 MAPK pathways. Flow cytometry showed the presence of beta1 and beta2 adrenoreceptors on resting mast cells. The enhancing effect of proatherogenic cytokine production by epinephrine was down regulated by the beta1 and beta2 adrenoceptor antagonist, propranolol, but not by the beta1 adrenoceptor antagonist, atenolol, suggesting the effect involved beta2 adrenoceptors. The enhancing effect of epinephrine on proatherogenic cytokine production was also down regulated by the immunosuppressive drug, dexamethasone. CONCLUSIONS: These results not only confirm that an acute phase cytokine, IL-1 beta, regulates mast cell function, but also show that epinephrine up regulates the IL-1 beta induction of proatherogenic cytokines in mast cells. These data provide a novel role for epinephrine, a stress hormone, in inflammation and atherogenesis. [Abstract/Link to Full Text]

Shen Y, Iqbal J, Xiao L, Lynch RC, Rosenwald A, Staudt LM, Sherman S, Dybkaer K, Zhou G, Eudy JD, Delabie J, McKeithan TW, Chan WC
Distinct gene expression profiles in different B-cell compartments in human peripheral lymphoid organs.
BMC Immunol. 2004 Sep 15;520.
BACKGROUND: There are three major B-cell compartments in peripheral lymphoid organs: the germinal center (GC), the mantle zone (MNZ) and the marginal zone (MGZ). Unique sets of B-cells reside in these compartments, and they have specific functional roles in humoral immune response. MNZ B cells are naive cells in a quiescent state and may participate in GC reactions upon proper stimulation. The adult splenic MGZ contains mostly memory B cells and is also known to provide a rapid response to particulate antigens. The GC B-cells proliferate rapidly and undergo selection and affinity maturation. The B-cell maturational process is accompanied by changes in the expression of cell-surface and intracellular proteins and requires signals from the specialized microenvironments. RESULTS: We performed laser microdissection of the three compartments for gene expression profiling by cDNA microarray. The transcriptional program of the GC was dominated by upregulation of genes associated with proliferation and DNA repair or recombination. The MNZ and MGZ showed increased expression of genes promoting cellular quiescence. The three compartments also revealed distinct repertoires of apoptosis-associated genes, chemokines and chemokine receptors. The MNZ and GC showed upregulation of CCL20 and CCL18 respectively. The MGZ was characterized by high expression of many chemokines genes e.g. CXCL12, CCL3, CCL14 and IFN-associated genes, consistent with its role in rapid response to infections. A stromal signature was identified including genes associated with macrophages or with synthesis of extracellular matrix and genes that influenced lymphocyte migration and survival. Differentially expressed genes that did not belong to the above categories include the well characterized BCL6 and CD10 and many others whose function is not known. CONCLUSIONS: Transcriptional profiling of B-cell compartments has identified groups of genes involved in critical molecular and cellular events that affect proliferation, survival migration, and differentiation of the cells. The gene expression study of normal B-cell compartments may additionally contribute to our understanding of the molecular abnormalities of the corresponding lymphoid tumors. [Abstract/Link to Full Text]

Jackson KJ, Gaeta B, Sewell W, Collins AM
Exonuclease activity and P nucleotide addition in the generation of the expressed immunoglobulin repertoire.
BMC Immunol. 2004 Sep 2;519.
BACKGROUND: Immunoglobulin rearrangement involves random and imprecise processes that act to both create and constrain diversity. Two such processes are the loss of nucleotides through the action of unknown exonuclease(s) and the addition of P nucleotides. The study of such processes has been compromised by difficulties in reliably aligning immunoglobulin genes and in the partitioning of nucleotides between segment ends, and between N and P nucleotides. RESULTS: A dataset of 294 human IgM sequences was created and partitioned with the aid of a probabilistic model. Non-random removal of nucleotides is seen between the three IGH gene types with the IGHV gene averaging removals of 1.2 nucleotides compared to 4.7 for the other gene ends (p < 0.001). Individual IGHV, IGHD and IGHJ gene subgroups also display statistical differences in the level of nucleotide loss. For example, within the IGHJ group, IGHJ3 has average removals of 1.3 nucleotides compared to 6.4 nucleotides for IGHJ6 genes (p < 0.002). Analysis of putative P nucleotides within the IgM and pooled datasets revealed only a single putative P nucleotide motif (GTT at the 3' D-REGION end) to occur at a frequency significantly higher then would be expected from random N nucleotide addition. CONCLUSIONS: The loss of nucleotides due to the action of exonucleases is not random, but is influenced by the nucleotide composition of the genes. P nucleotides do not make a significant contribution to diversity of immunoglobulin sequences. Although palindromic sequences are present in 10% of immunologlobulin rearrangements, most of the 'palindromic' nucleotides are likely to have been inserted into the junction during the process of N nucleotide addition. P nucleotides can only be stated with confidence to contribute to diversity of less than 1% of sequences. Any attempt to identify P nucleotides in immunoglobulins is therefore likely to introduce errors into the partitioning of such sequences. [Abstract/Link to Full Text]


Recent Articles in BMC Infectious Diseases

Faburay B, Geysen D, Munstermann S, Bell-Sakyi L, Jongejan F
Longitudinal monitoring of Ehrlichia ruminantium infection in Gambian lambs and kids by pCS20 PCR and MAP1-B ELISA.
BMC Infect Dis. 2007;785.
BACKGROUND: The epidemiology of E. ruminantium infection in extensively managed young animals is not adequately understood. Thus in this study, we monitored the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response in extensively managed newborn lambs and kids at three sites in The Gambia. METHODS: We used a nested pCS20 PCR and MAP1-B ELISA in a longitudinal study to monitor the onset (age at first infection) and kinetics of E. ruminantium infection and antibody response respectively, in 77 newborn lambs and kids under a traditional husbandry system at three sites (Kerr Seringe, Keneba, Bansang) in The Gambia where heartwater is known to occur. The animals were monitored for field tick infestation and the comparative performance of the two assays in detecting E. ruminantium infection was also assessed. RESULTS: The infection rate detected by pCS20 PCR varied between 8.6% and 54.8% over the 162-day study period. Nineteen per cent of the animals in week 1 post-partum tested positive by pCS20 PCR with half of these infections (7/14) detected in the first 3 days after birth, suggesting that transmission other than by tick feeding had played a role. The earliest detectable A. variegatum infestation in the animals occurred in week 16 after birth. Antibodies detected by MAP1-B ELISA also varied, between 11.5% and 90%. Although there is considerable evidence that this assay can detect false positives and due to this and other reasons serology is not a reliable predictor of infection at least for heartwater. In contrast to the pCS20 PCR, the serological assay detected the highest proportion of positive animals in week 1 with a gradual decline in seropositivity with increasing age. The pCS20 PCR detected higher E. ruminantium prevalence in the animals with increasing age and both the Spearman's rank test (rs = -0.1512; P = 0.003) and kappa statistic (-0.091 to 0.223) showed a low degree of agreement between the two assays. CONCLUSION: The use of pCS20 PCR supported by transmission studies and clinical data could provide more accurate information on heartwater epidemiology in endemic areas and single-occasion testing of an animal may not reveal its true infection status. The view is supported because both the vector and vertical transmission may play a vital role in the epidemiology of heartwater in young small ruminants; the age range of 4 and 12 weeks corresponds to the period of increased susceptibility to heartwater in traditionally managed small ruminants. [Abstract/Link to Full Text]

Murphy DJ, Brown JR
Identification of gene targets against dormant phase Mycobacterium tuberculosis infections.
BMC Infect Dis. 2007;784.
BACKGROUND: Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), infects approximately 2 billion people worldwide and is the leading cause of mortality due to infectious disease. Current TB therapy involves a regimen of four antibiotics taken over a six month period. Patient compliance, cost of drugs and increasing incidence of drug resistant M. tuberculosis strains have added urgency to the development of novel TB therapies. Eradication of TB is affected by the ability of the bacterium to survive up to decades in a dormant state primarily in hypoxic granulomas in the lung and to cause recurrent infections. METHODS: The availability of M. tuberculosis genome-wide DNA microarrays has lead to the publication of several gene expression studies under simulated dormancy conditions. However, no single model best replicates the conditions of human pathogenicity. In order to identify novel TB drug targets, we performed a meta-analysis of multiple published datasets from gene expression DNA microarray experiments that modeled infection leading to and including the dormant state, along with data from genome-wide insertional mutagenesis that examined gene essentiality. RESULTS: Based on the analysis of these data sets following normalization, several genome wide trends were identified and used to guide the selection of targets for therapeutic development. The trends included the significant up-regulation of genes controlled by devR, down-regulation of protein and ATP synthesis, and the adaptation of two-carbon metabolism to the hypoxic and nutrient limited environment of the granuloma. Promising targets for drug discovery were several regulatory elements (devR/devS, relA, mprAB), enzymes involved in redox balance and respiration, sulfur transport and fixation, pantothenate, isoprene, and NAD biosynthesis. The advantages and liabilities of each target are discussed in the context of enzymology, bacterial pathways, target tractability, and drug development. CONCLUSION: Based on our bioinformatics analysis and additional discussion of in-depth biological rationale, several novel anti-TB targets have been proposed as potential opportunities to improve present therapeutic treatments for this disease. [Abstract/Link to Full Text]

Martinez V, Carcelain G, Badell E, Jouan M, Mauger I, Sellier P, Truffot C, Bricaire F, Arend SM, Ottenhoff T, Autran B, Gicquel B
T-cell and serological responses to Erp, an exported Mycobacterium tuberculosis protein, in tuberculosis patients and healthy individuals.
BMC Infect Dis. 2007;783.
BACKGROUND: The identification of antigens able to differentiate tuberculosis (TB) disease from TB infection would be valuable. Cellular and humoral immune responses to Erp (Exported repetitive protein)--a recently identified M. tuberculosis protein--have not yet been investigated in humans and may contribute to this aim. METHODS: We analyzed the cellular and humoral immune responses to Erp, ESAT-6, Ag85B and PPD in TB patients, in BCG+ individuals without infection, BCG+ individuals with latent TB infection (LTBI) and BCG- controls. We used lymphoproliferation, ELISpot IFN-gamma, cytokine production assays and detection of specific human antibodies against recombinant M. tuberculosis proteins. RESULTS: We included 22 TB patients, 9 BCG+ individuals without TB infection, 7 LTBI and 7 BCG- controls. Erp-specific T cell counts were higher in LTBI than in the other groups. Erp-specific T cell counts were higher in LTBI subjects than TB patients (median positive frequency of 211 SFC/106 PBMC (range 118-2000) for LTBI subjects compared to 80 SFC/106 PBMC (range 50-191), p = 0.019); responses to PPD and ESAT-6 antigens did not differ between these groups. IFN-gamma secretion after Erp stimulation differed between TB patients and LTBI subjects (p = 0.02). Moreover, LTBI subjects but not TB patients or healthy subjects produced IgG3 against Erp. CONCLUSION: The frequencies of IFN-gamma-producing specific T cells, the IFN-gamma secretion and the production of IgG3 after Erp stimulation are higher in LTBI subjects than in TB patients, whereas PPD and ESAT-6 are not. [Abstract/Link to Full Text]

Gordon M, Roberts H, Odeka E
Knowledge and attitudes of parents and professionals to neonatal BCG vaccination in light of recent UK policy changes: a questionnaire study.
BMC Infect Dis. 2007;782.
BACKGROUND: Universal BCG vaccination in the UK ended in 2005. The new vaccination policy instead offers a number of different forms of selective vaccination to newborns based on risk of acquiring TB. We set out to assess the attitudes and knowledge of both parents and professionals to the new policy for neonatal BCG vaccination. METHODS: A short questionnaire was designed, made up of demographic and attitude questions, as well as very basic knowledge questions. The researchers handed out the questionnaire to all parents and professionals in the antenatal and postnatal areas, as well as the paediatric and neonatal units during a 6-week period. The site was the Royal Oldham hospital, a district general hospital with 3250 deliveries per year and multi-ethnic in its population mix. RESULTS: A total of 253 completed questionnaires were collected. The ethnic origin of responders was 50.6% White British, 18.2% Bangladeshi, 8.7% Indian, 4% White/Asian, the remaining 18.5% of other origins. 71.5% of responders said they had heard of BCG vaccine. When asked if they knew the new policy for its use, 33.2% answered yes. 24.5% gave the most accurate response when asked who now receives BCG. CONCLUSION: We have found that amongst parents and professionals alike there is a lack of knowledge of the new policy. This has lead to confusion and as knowledge amongst the professionals who identify neonates for vaccination is low, uptake may be sub-optimal. We suggest that units investigate the issue and ensure that the new policy is understood and implemented correctly. [Abstract/Link to Full Text]

Janjua NZ, Razaq M, Chandir S, Rozi S, Mahmood B
Poor knowledge--predictor of nonadherence to universal precautions for blood borne pathogens at first level care facilities in Pakistan.
BMC Infect Dis. 2007;781.
BACKGROUND: We conducted an assessment of knowledge about blood borne pathogens (BBP) and use of universal precautions at first level care facilities (FLCF) in two districts of Pakistan. METHODS: We conducted a cross-sectional survey and selected three different types of FLCFs ; public, general practitioners and unqualified practitioners through stratified random sampling technique. At each facility, we interviewed a prescriber, a dispenser, and a housekeeper for knowledge of BBPs transmission and preventive practices, risk perception, and use of universal precautions. We performed multiple linear regression to assess the effect of knowledge score (11 items) on the practice of universal precautions score (4 items- use of gloves, gown, needle recapping, and HBV vaccination). RESULTS: We interviewed 239 subjects. Most of the participants 128 (53%) were recruited from general practitioners clinics and 166 (69.5%) of them were dispensers. Mean (SD) knowledge score was 3.8 (2.3) with median of 4. MBBS prescribers had the highest knowledge score while the housekeepers had the lowest. Mean universal precautions use score was 2.7 +/- 2.1. Knowledge about mode of transmission and the work experience alone, significantly predicted universal precaution use in multiple linear regression model (adR2 = 0.093). CONCLUSION: Knowledge about mode of transmission of blood borne pathogens is very low. Use of universal precautions can improve with increase in knowledge. [Abstract/Link to Full Text]

Madani TA, Ghabrah TM
Meningococcal, influenza virus, and hepatitis B virus vaccination coverage level among health care workers in Hajj.
BMC Infect Dis. 2007;780.
BACKGROUND: The objective of this study was to assess the compliance of health care workers (HCWs) employed in Hajj in receiving the meningococcal, influenza, and hepatitis B vaccines. METHODS: A cross-sectional survey of doctors and nurses working in all Mena and Arafat hospitals and primary health care centers who attended Hajj-medicine training programs immediately before the beginning of Hajj of the lunar Islamic year 1423 (2003) using self-administered structured questionnaire which included demographic data and data on vaccination history. RESULTS: A total of 392 HCWs were studied including 215 (54.8%) nurses and 177 (45.2%) doctors. One hundred and sixty four (41.8%) HCWs were from Makkah and the rest were recruited from other regions in Saudi Arabia. Three hundred and twenty three (82.4%) HCWs received the quadrivalent (ACYW135) meningococcal meningitis vaccine with 271 (83.9%) HCWs receiving it at least 2 weeks before coming to Hajj, whereas the remaining 52 (16.1%) HCWs received it within < 2 weeks. Only 23 (5.9%) HCWs received the current year's influenza virus vaccine. Two hundred and sixty (66.3%) of HCWs received the three-dose hepatitis B vaccine series, 19.3% received one or two doses, and 14.3% did not receive any dose. There was no statistically significant difference in compliance with the three vaccines between doctors and nurses. CONCLUSION: The meningococcal and hepatitis B vaccination coverage level among HCWs in Hajj was suboptimal and the influenza vaccination level was notably low. Strategies to improve vaccination coverage among HCWs should be adopted by all health care facilities in Saudi Arabia. [Abstract/Link to Full Text]

Lee SC, Huang SS, Lee CW, Fung CP, Lee N, Shieh WB, Siu LK
Comparative antimicrobial susceptibility of aerobic and facultative bacteria from community-acquired bacteremia to ertapenem in Taiwan.
BMC Infect Dis. 2007;779.
BACKGROUND: Ertapenem is a once-a-day carbapenem and has excellent activity against many gram-positive and gram-negative aerobic, facultative, and anaerobic bacteria. The susceptibility of isolates of community-acquired bacteremia to ertapenem has not been reported yet. The present study assesses the in vitro activity of ertapenem against aerobic and facultative bacterial pathogens isolated from patients with community-acquired bacteremia by determining and comparing the MICs of cefepime, cefoxitin, ceftazidime, ceftriaxone, ertapenem, piperacillin, piperacillin-tazobactam, ciprofloxacin, amikacin and gentamicin. The prevalence of extended broad spectrum beta-lactamases (ESBL) producing strains of community-acquired bacteremia and their susceptibility to these antibiotics are investigated. METHODS: Aerobic and facultative bacteria isolated from blood obtained from hospitalized patients with community-acquired bacteremia within 48 hours of admission between August 1, 2004 and September 30, 2004 in Chang Gung Memorial Hospital at Keelung, Taiwan, were identified using standard procedures. Antimicrobial susceptibility was evaluated by Etest according to the standard guidelines provided by the manufacturer and document M100-S16 Performance Standards of the Clinical Laboratory of Standard Institute. Antimicrobial agents including cefepime, cefoxitin, ceftazidime, ceftriaxone, ertapenem, piperacillin, piperacillin-tazobactam, ciprofloxacin, amikacin and gentamicin were used against the bacterial isolates to test their MICs as determined by Etest. For Staphylococcus aureus isolates, MICs of oxacillin were also tested by Etest to differentiate oxacillin-sensitive and oxacillin-resistant S. aureus. RESULTS: Ertapenem was highly active in vitro against many aerobic and facultative bacterial pathogens commonly recovered from patients with community-acquired bacteremia (128/159, 80.5 %). Ertapenem had more potent activity than ceftriaxone, piperacillin-tazobactam, or ciprofloxacin against oxacillin-susceptible S. aureus (17/17, 100%)and was more active than any of these agents against enterobacteriaceae (82/82, 100%). CONCLUSION: Based on the microbiology pattern of community-acquired bacteremia, initial empiric treatment that requires coverage of a broad spectrum of both gram-negative and gram-positive aerobic bacteria, such as ertapenem, may be justified in moderately severe cases of community-acquired bacteremia in non-immunocompromised hosts. [Abstract/Link to Full Text]

Heiro M, Helenius H, Hurme S, Savunen T, Engblom E, Nikoskelainen J, Kotilainen P
Short-term and one-year outcome of infective endocarditis in adult patients treated in a Finnish teaching hospital during 1980-2004.
BMC Infect Dis. 2007;778.
BACKGROUND: Previous studies on factors predicting the prognosis of infective endocarditis have given somewhat conflicting results. Our aim was to define the factors predicting the outcome of patients treated in a Finnish teaching hospital. METHODS: A total of 326 episodes of infective endocarditis in 303 patients treated during 1980-2004 were evaluated for short-term and 1-year outcome and complications. RESULTS: Infection of 2 native valves and the occurrence of neurological complications, peripheral emboli, or heart failure significantly predicted both in-hospital and 1-year mortality, while age > or =65 years or the presence of a major criterion or vegetation on echocardiography predicted death within 1 year. A significant trend was observed between the level of serum C-reactive protein (CRP) on admission and both the short-term and 1-year outcome. In the patients who had CRP values > or =100 mg/l on admission, the hazard ratio for in-hospital death was 2.9-fold and the hazard ratio for 1-year death was 3.9-fold as compared to those with lower CRP values. Male sex and age < 64 years significantly predicted a need for both in-hospital and 1-year surgery, as did the development of heart failure or the presence of a major criterion or vegetation on echocardiography. Peripheral emboli were associated with a need for in-hospital surgery, while Streptococcus pneumoniae as the causative agent or infection of 2 native valves predicted a need for surgery within 1 year from admission. CONCLUSION: Some of the factors (e.g. heart failure, neurological complications, peripheral emboli) predicting a poor prognosis and/or need for surgery were the same observed in previous studies. A new finding was that high CRP values (> or =100 mg/l) on admission significantly predicted both short-term and 1-year mortality. [Abstract/Link to Full Text]

Ng'andwe C, Lowe JJ, Richards PJ, Hause L, Wood C, Angeletti PC
The distribution of sexually-transmitted Human Papillomaviruses in HIV positive and negative patients in Zambia, Africa.
BMC Infect Dis. 2007;777.
BACKGROUND: Human Papillomaviruses (HPV) are double-stranded DNA viruses, considered to be the primary etiological agents in cervical intraepithelial neoplasias and cancers. Approximately 15-20 of the 40 mucosal HPVs confer a high-risk of progression of lesions to invasive cancer. In this study, we investigated the prevalence of sexually transmitted HPVs in Human Immunodeficiency Virus (HIV) positive and negative patients in Zambia, Africa. The rate of high-risk HPV genotypes worldwide varies within each country. Thus, we sought to investigate the rates of HPV infection in sub-Saharan Africa and the potential role of HIV in affecting the HPV genotype distribution. METHODS: This retrospective cross-sectional study reports findings on the association and effects of HIV on HPV infections in an existing cohort of patients at University Teaching Hospital (UTH) Lusaka, Zambia. The objective of this study was to assess HPV prevalence, genotype distribution and to identify co-factors that influence HPV infection. Polymerase chain reaction (PCR) with two standard consensus primer sets (CpI/II and GP5+/6+) was used to test for the presence of HPV DNA. Primers specific for beta-actin were used to monitor DNA quality. Vaginal lavage samples, collected between 1998-1999 from a total of 70 women, were part of a larger cohort that was also analyzed for HIV and human herpesvirus infection. Seventy of the samples yielded usable DNA. HIV status was determined by two rapid assays, Capillus and Determine. The incidence of HIV and HPV infections and HPV genotype distributions were calculated and statistical significance was determined by Chi-Squared test. RESULTS: We determined that most common HPV genotypes detected among these Zambian patients were types 16 and 18 (21.6% each), which is approximately three-fold greater than the rates for HPV16, and ten-fold greater than the rates for HPV18 in the United States. The worldwide prevalence of HPV16 is approximately 14% and HPV18 is 5%. The overall ratio of high-risk (HR) to low-risk (LR) HPVs in the patient cohort was 69% and 31% respectively; essentially identical to that for the HR and LR distributions worldwide. However, we discovered that HIV positive patients were two-times as likely to have an HR HPV as HIV negative individuals, while the distribution of LR HPVs was unaffected by HIV status. Interestingly, we observed a nine-fold increase in HPV18 infection frequency in HIV positive versus HIV negative individuals. CONCLUSION: The rate of oncogenic HPVs (type 16 and 18) in Zambia was much higher than in the U.S., potentially providing an explanation for the high-rates of cervical cancer in Zambia. Surprisingly, we discovered a strong association between positive HIV status and the prevalence of HR HPVs, and specifically HPV18. [Abstract/Link to Full Text]

Duerr HP, Brockmann SO, Piechotowski I, Schwehm M, Eichner M
Influenza pandemic intervention planning using InfluSim: pharmaceutical and non- pharmaceutical interventions.
BMC Infect Dis. 2007;776.
BACKGROUND: Influenza pandemic preparedness plans are currently developed and refined on national and international levels. Much attention has been given to the administration of antiviral drugs, but contact reduction can also be an effective part of mitigation strategies and has the advantage to be not limited per se. The effectiveness of these interventions depends on various factors which must be explored by sensitivity analyses, based on mathematical models. METHODS: We use the freely available planning tool InfluSim to investigate how pharmaceutical and non-pharmaceutical interventions can mitigate an influenza pandemic. In particular, we examine how intervention schedules, restricted stockpiles and contact reduction (social distancing measures and isolation of cases) determine the course of a pandemic wave and the success of interventions. RESULTS: A timely application of antiviral drugs combined with a quick implementation of contact reduction measures is required to substantially protract the peak of the epidemic and reduce its height. Delays in the initiation of antiviral treatment (e.g. because of parsimonious use of a limited stockpile) result in much more pessimistic outcomes and can even lead to the paradoxical effect that the stockpile is depleted earlier compared to early distribution of antiviral drugs. CONCLUSION: Pharmaceutical and non-pharmaceutical measures should not be used exclusively. The protraction of the pandemic wave is essential to win time while waiting for vaccine development and production. However, it is the height of the peak of an epidemic which can easily overtax general practitioners, hospitals or even whole public health systems, causing bottlenecks in basic and emergency medical care. [Abstract/Link to Full Text]

Alvarado-Esquivel C, Mercado-Suarez MF, Rodríguez-Briones A, Fallad-Torres L, Ayala-Ayala JO, Nevarez-Piedra LJ, Duran-Morales E, Estrada-Martínez S, Liesenfeld O, Márquez-Conde JA, Martínez-García SA
Seroepidemiology of infection with Toxoplasma gondii in healthy blood donors of Durango, Mexico.
BMC Infect Dis. 2007;775.
BACKGROUND: Toxoplasma gondii (T. gondii) infection in blood donors could represent a risk for transmission in blood recipients. There is scarce information about the epidemiology of T. gondii infection in blood donors in Mexico. Therefore, we sought to determine the prevalence of T. gondii infection and associated socio-demographic and behavioral characteristics in a population of healthy blood donors of Durango City, Mexico. METHODS: Four hundred and thirty two blood donors in two public blood banks of Durango City, Mexico were examined for T. gondii infection between August to September 2006. Blood donors were tested for anti-T. gondii IgG and IgM antibodies by using enzyme-linked immunoassays (Diagnostic Automation Inc., Calabasas, CA, USA). Socio-demographic and behavioral characteristics from each participant were also obtained. RESULTS: Thirty two (7.4%) of 432 blood donors had IgG anti-T. gondii antibodies. Eight (1.9%) of them had also IgM anti-T. gondii antibodies. Multivariate analysis using logic regression showed that T. gondii infection was associated with the presence of cats at home (adjusted OR = 3.81; 95% CI: 1.45-10.01). The age group of 45-60 years showed a significantly higher frequency of T. gondii infection than the group of 25-34 years (p = 0.02). Blood donors without education had a significantly higher frequency of infection (15.8%) than those with 13-19 years of education (4.5%) (p = 0.04). Other characteristics of blood donors including male gender, consumption of undercooked meat or blood transfusion did not show an association with infection. CONCLUSION: The prevalence of T. gondii infection in healthy blood donors of Durango City, Mexico is lower than those reported in blood donors of south and central Mexico, and is one of the lowest reported in blood donors worldwide. T. gondii infection in our blood donors was most likely acquired by contact with cats. Prevalence of infection increased with age and decreased with educational level. [Abstract/Link to Full Text]

Kashyap RS, Rajan AN, Ramteke SS, Agrawal VS, Kelkar SS, Purohit HJ, Taori GM, Daginawala HF
Diagnosis of tuberculosis in an Indian population by an indirect ELISA protocol based on detection of Antigen 85 complex: a prospective cohort study.
BMC Infect Dis. 2007;774.
BACKGROUND: Diagnosis of tuberculosis (TB) remains problematic despite many new advanced diagnostic methods. A reliable and rapid diagnostic test, which could be performed in any standard pathology laboratory, would help to obtain definitive early diagnoses of TB. In the present study we describe a prospective evaluation for demonstrating Antigen (Ag) 85 complex in the sera from TB patients. METHODS: Indirect ELISA, employing monoclonal antibodies (mAb) against the purified Ag 85 complex, was used to demonstrate Ag 85 complex in sera from TB patients. Serum samples were obtained from 197 different groups of patients: confirmed TB {n = 24}, clinically diagnosed TB {n = 104}, disease controls {n = 49} and healthy controls {n = 20}. Receiver operating curve (ROC) was used to calculate the cut off value and comparison between TB and non-TB groups were done by the chi-square test. RESULTS: The indirect ELISA method, using an mAb against Ag 85 complex, yielded 82% sensitivity (95% confidence interval [CI] 67 to 93%) and 86% specificity (95% CI, 57 to 98%) for the diagnosis of TB. The serum positivities for Ag 85 complex in cases of confirmed and clinically diagnosed TB patients were 96% (23/24) and 79% (82/104) respectively, while the positivity for patients in the non-tuberculosis group was 14% (10/69). CONCLUSION: The detection of Ag 85 complex in sera from TB patients by indirect ELISA using mAb against purified Ag 85 complex gives a reliable diagnosis and can be used to develop an immunodiagnostic assay with increased sensitivity and specificity. [Abstract/Link to Full Text]

Domínguez A, Bruguera M, Plans P, Espuñes J, Costa J, Plasencia A, Salleras L
Declining hepatitis A seroprevalence in adults in Catalonia (Spain): a population-based study.
BMC Infect Dis. 2007;773.
BACKGROUND: One of the main uses of seroprevalence studies it to evaluate vaccination programmes. In 1998, a programme of universal vaccination of preadolescents in schools with the hepatitis A vaccine was begun in Catalonia. The objective of this study was to investigate the prevalence and risk factors of hepatitis A virus infection (HAV) in a sample of the adult population of Catalonia in 2002 and to evaluate the changes with respect to a survey carried out in 1996. METHODS: The prevalence of HAV antibodies was determined by a third generation competitive immunometric assay in a representative sample of 1292 people aged >15 years. The association between the prevalence and different sociodemographic variables was determined by multiple logistic regression analysis. RESULTS: The standardized global prevalence of HAV antibodies in 2002 was 68.2%, increased with age (p < 0.0001) and was associated with being born outside Catalonia (OR: 1.75; 95% CI 1.11-2.76) and lower social class (OR: 1.14; 95% CI 1.05-1.25). Compared with the last survey carried out in 1996 the standardized global prevalence was lower (68.2% vs 77.8%; p < 0.0001) as was the prevalence in people under 45 years. CONCLUSION: The prevalence of the hepatitis A virus is decreasing in the adult population of Catalonia, especially in the younger age groups. The programme of vaccination of adolescents begun in 1998 to control the disease can provide indirect protection to the unvaccinated population. [Abstract/Link to Full Text]

Niedrig M, Donoso Mantke O, Altmann D, Zeller H
First international diagnostic accuracy study for the serological detection of West Nile virus infection.
BMC Infect Dis. 2007;772.
BACKGROUND: The diagnosis of an acute or convalescent West Nile (WN) virus infection can be confirmed by various serological assays such as enzyme immunoassay (EIA), immunofluorescence assay (IFA), or neutralisation test (NT) which are conducted by a growing number of laboratories. However, as the degree of proficiency may vary between laboratories, quality control measures for laboratory diagnostics are essential. METHODS: We have performed an external quality assurance (EQA) programme for the serological detection of WN virus infection to assess the diagnostic quality of laboratories. The participating laboratories received a proficiency panel of 10 coded lyophilised test samples comprising four antisera positive for WN antibodies as positive controls, three antisera positive for antibodies against other heterologous flaviviruses plus one multireactive unspecific serum as specificity controls, and two negative serum samples. RESULTS: Twenty-seven laboratories from 20 different countries in Europe, the Middle East, the Americas and Africa participated in this EQA programme. Applying the proficiency criteria of this study, only eight laboratories correctly analysed all samples with their respective EIA, IFA or NT methods. Eighteen laboratories correctly identified between 77.8 and 90% of the samples, and one laboratory identified only 70% correctly with a clear need to eliminate cross-reactivity with other antisera, particularly those elicited by yellow fever virus. Differentiation between the results for IgM and IgG was considered separately and revealed that IgM-antibodies were detected less frequently than IgG-antibodies (p < 0.001). However, the assay used was not a significant technical factor influencing laboratory performance. CONCLUSION: The EQA programme provides information on the quality of different serological assays used by the participating laboratories and indicates that most need to improve their assays, in particular to avoid cross-reactions with antibodies to heterologous flaviviruses. [Abstract/Link to Full Text]

Colugnati FA, Staras SA, Dollard SC, Cannon MJ
Incidence of cytomegalovirus infection among the general population and pregnant women in the United States.
BMC Infect Dis. 2007;771.
BACKGROUND: Cytomegalovirus (CMV) is a common opportunistic infection among HIV-infected individuals, a major source of serious complications among organ-transplant recipients, and a leading cause of hearing loss, vision loss, and mental retardation among congenitally infected children. Women infected for the first time during pregnancy are especially likely to transmit CMV to their fetuses. More children suffer serious disabilities caused by congenital CMV than by several better-known childhood maladies such as Down syndrome or fetal alcohol syndrome METHODS: Using CMV seroprevalence data from the nationally representative Third National Health and Nutrition Examination Survey, we estimated CMV incidence among the general United States population and among pregnant women. We employed catalytic models that used age-specific CMV seroprevalences as cumulative markers of past infections in order to derive estimates of three basic parameters: the force of infection, the basic reproductive rate, and the average age of infection. Our main focus was the force of infection, an instantaneous per capita rate of acquisition of infection that approximates the incidence of infection in the seronegative population. RESULTS: Among the United States population ages 12-49 the force of infection was 1.6 infections per 100 susceptible persons per year (95% confidence interval: 1.2, 2.4). The associated basic reproductive rate of 1.7 indicates that, on average, an infected person transmits CMV to nearly two susceptible people. The average age of CMV infection was 28.6 years. Force of infection was significantly higher among non-Hispanic Blacks (5.7) and Mexican Americans (5.1) than among non-Hispanic Whites (1.4). Force of infection was significantly higher in the low household income group (3.5) than in the middle (2.1) and upper (1.5) household income groups. Based on these CMV incidence estimates, approximately 27,000 new CMV infections occur among seronegative pregnant women in the United States each year. CONCLUSION: These thousands of CMV infections in pregnant women, along with the sharp racial/ethnic disparities in CMV incidence, are compelling reasons for accelerating research on vaccines and other interventions for preventing congenital CMV disease. Nevertheless, the relatively low force of infection provides encouraging evidence that modestly effective vaccines and rates of vaccination could significantly reduce CMV transmission. [Abstract/Link to Full Text]

Riedel A, Choe L, Inciardi J, Yuen C, Martin T, Guglielmo BJ
Antifungal prophylaxis in chemotherapy-associated neutropenia: a retrospective, observational study.
BMC Infect Dis. 2007;770.
BACKGROUND: In August 2002, the antifungal prophylaxis algorithm for neutropenic hematology/oncology (NHO) patients at the Medical Center was changed from conventional amphotericin (AMB) to an azole (AZ) based regimen (fluconazole [FLU] in low-risk and voriconazole [VOR] in high-risk patients). The aim of our study was to compare outcomes associated with the two regimens, including breakthrough fungal infection, adverse drug events, and costs. METHODS: Adult, non-febrile, NHO patients who received prophylactic AMB from 01 August 2001-30 July 2002 or AZ from 01 August 2002-30 July 2003 were retrospectively evaluated. RESULTS: A total of 370 patients (AMB: n = 181; AZ: n = 216) associated with 580 hospitalizations (AMB: n = 259; AZ: n = 321) were included. The incidence of probable/definite breakthrough Aspergillus infections was similar among regimens (AMB: 1.9% vs AZ: 0.6%; p=0.19). A greater incidence of mild/moderate (24.7% vs. 5.3%; p < 0.0001) and severe renal dysfunction (13.5% vs. 4.4%; p < 0.0012) was observed with AMB. In contrast, patients treated with VOR were found to have an increased rate of severe hepatic toxicity (32.5%) compared with patients treated with either AMB (22.6%) or FLU (21.4%) (p = 0.05). While the AZ period was associated with a >$9,000 increase in mean total costs/hospitalization, the mean acquisition cost associated with AZ was only $947/hospitalization more than AMB. CONCLUSION: While an AZ-based regimen is associated with increased cost, the reduced rate of nephrotoxicity and availability of oral dosage forms, suggests that azoles be used preferentially over AMB. However, an increased rate of severe hepatic toxicity may be associated with VOR. [Abstract/Link to Full Text]

Kulwichit W, Nilgate S, Chatsuwan T, Krajiw S, Unhasuta C, Chongthaleong A
Accuracies of Leuconostoc phenotypic identification: a comparison of API systems and conventional phenotypic assays.
BMC Infect Dis. 2007;769.
BACKGROUND: Commercial diagnostics are commonly used to identify gram-positive bacteria. Errors have been reported mostly at the species level. We have found certain phenotypic criteria used in API systems which significantly misidentify Leuconostoc, an emerging human pathogen, at the genus level. We also attempt to find practical, conventional phenotypic assays for accurate identification of this group of bacteria. METHODS: Clinical isolates of catalase-negative, gram-positive coccoid or coccobacillary bacteria with non-beta hemolysis in our institute during 1997-2004 were subject to an identification aid by API 20 STREP, following the instruction manual, as an aid to conventional phenotypic tests. Those identified as Leuconostoc by API 20 STREP were re-examined by the same kit and also by API 50 CHL according to the instruction manuals, by our Leuconostoc conventional phenotypic assays, by Leuconostoc- and Lactobacillus-specific PCR's, and, where possible, by 16S rDNA sequence analysis. In addition, catalase-negative gram-positive isolates during 2005-2006 which were resistant to vancomycin at high levels were also evaluated by the same phenotypic and genotypic assays. RESULTS: Out of several thousands of clinical gram-positive isolates, 26 catalase negative gram-positive isolates initially identified as Leuconostoc by API 20 STREP and 7 vancomycin-resistant gram-positive catalase-negative bacteria entered the study. 11 out of the 26 isolates and all the 7 isolates were identified as Leuconostoc by API 20 STREP. Only 5 isolates, however, were confirmed by both genotypic and all defined conventional phenotypic criteria. API 50 CHL also failed to reliably provide accurate identification of Leuconostoc. We have identified key problem tests in API 20 STREP leading to misidentification of the bacteria. A simple, conventional set of phenotypic tests for Leuconostoc identification is proposed. CONCLUSION: The current API systems cannot accurately identify Leuconostoc. Identification of vancomycin-resistant, catalase-negative gram-positive bacteria should be performed by a few practical phenotypic assays, with assistance of genotypic assays where available. [Abstract/Link to Full Text]

Currie BJ, Gal D, Mayo M, Ward L, Godoy D, Spratt BG, LiPuma JJ
Using BOX-PCR to exclude a clonal outbreak of melioidosis.
BMC Infect Dis. 2007;768.
BACKGROUND: Although melioidosis in endemic regions is usually caused by a diverse range of Burkholderia pseudomallei strains, clonal outbreaks from contaminated potable water have been described. Furthermore B. pseudomallei is classified as a CDC Group B bioterrorism agent. Ribotyping, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) have been used to identify genetically related B. pseudomallei isolates, but they are time consuming and technically challenging for many laboratories. METHODS: We have adapted repetitive sequence typing using a BOX A1R primer for typing B. pseudomallei and compared BOX-PCR fingerprinting results on a wide range of well-characterized B. pseudomallei isolates with MLST and PFGE performed on the same isolates. RESULTS: BOX-PCR typing compared favourably with MLST and PFGE performed on the same isolates, both discriminating between the majority of multilocus sequence types and showing relatedness between epidemiologically linked isolates from various outbreak clusters. CONCLUSION: Our results suggest that BOX-PCR can be used to exclude a clonal outbreak of melioidosis within 10 hours of receiving the bacterial strains. [Abstract/Link to Full Text]

Wilson S, Booth M, Jones FM, Mwatha JK, Kimani G, Kariuki HC, Vennervald BJ, Ouma JH, Muchiri E, Dunne DW
Age-adjusted Plasmodium falciparum antibody levels in school-aged children are a stable marker of microgeographical variations in exposure to Plasmodium infection.
BMC Infect Dis. 2007;767.
BACKGROUND: Amongst school-aged children living in malaria endemic areas, chronic morbidity and exacerbation of morbidity associated with other infections are often not coincident with the presence or levels of Plasmodium parasitaemia, but may result from long-term exposure to the parasite. Studies of hepatosplenomegaly associated with Schistosoma mansoni infection and exposure to Plasmodium infection indicate that differences that occur over 1-2 km in levels of Plasmodium transmission are related to the degree of exacerbation of hepatosplenomegaly and that Plasmodium falciparum schizont antigen (Pfs)-IgG3 levels may be a marker for the differing levels of exposure. METHODS: To investigate the validity of Pfs-IgG3 measurements as a tool to assess these comparative exposure levels on a microgeographical scale, cross-sectional community surveys were conducted over a 10 x 6 km study site in Makueni District, Kenya, during low and high malaria transmission seasons. During both high and low malaria transmission seasons, thick blood smears were examined microscopically and circulating Pfs-IgG3 levels measured from dried blood spot elute. GIS techniques were used to map prevalence of parasitaemia and Pfs-IgG3 levels. RESULTS: Microgeographical variations in prevalence of parasitaemia were observed during the high but not the low transmission season. Pfs-IgG3 levels were stable between high and low transmission seasons, but increased with age throughout childhood before reaching a plateau in adults. Adjusting Pfs-IgG3 levels of school-aged children for age prior to mapping resulted in spatial patterns that reflected the microgeographical variations observed for high season prevalence of parasitaemia, however, Pfs-IgG3 levels of adults did not. The distances over which age-adjusted Pfs-IgG3 of school-aged children fluctuated were comparable with those distances over which chronic morbidity has previous been shown to vary. CONCLUSION: Age-adjusted Pfs-IgG3 levels of school-aged children are stable and when mapped can provide a tool sensitive enough to detect microgeographical variations in malaria exposure, that would be useful for studying the aetiology of morbidities associated with long-term exposure and co-infections. [Abstract/Link to Full Text]

Pizarro JC, Lucero DE, Stevens L
PCR reveals significantly higher rates of Trypanosoma cruzi infection than microscopy in the Chagas vector, Triatoma infestans: high rates found in Chuquisaca, Bolivia.
BMC Infect Dis. 2007;766.
BACKGROUND: The Andean valleys of Bolivia are the only reported location of sylvatic Triatoma infestans, the main vector of Chagas disease in this country, and the high human prevalence of Trypanosoma cruzi infection in this region is hypothesized to result from the ability of vectors to persist in domestic, peri-domestic, and sylvatic environments. Determination of the rate of Trypanosoma infection in its triatomine vectors is an important element in programs directed at reducing human infections. Traditionally, T. cruzi has been detected in insect vectors by direct microscopic examination of extruded feces, or dissection and analysis of the entire bug. Although this technique has proven to be useful, several drawbacks related to its sensitivity especially in the case of small instars and applicability to large numbers of insects and dead specimens have motivated researchers to look for a molecular assay based on the polymerase chain reaction (PCR) as an alternative for parasitic detection of T. cruzi infection in vectors. In the work presented here, we have compared a PCR assay and direct microscopic observation for diagnosis of T. cruzi infection in T. infestans collected in the field from five localities and four habitats in Chuquisaca, Bolivia. The efficacy of the methods was compared across nymphal stages, localities and habitats. METHODS: We examined 152 nymph and adult T. infestans collected from rural areas in the department of Chuquisaca, Bolivia. For microscopic observation, a few drops of rectal content obtained by abdominal extrusion were diluted with saline solution and compressed between a slide and a cover slip. The presence of motile parasites in 50 microscopic fields was registered using 400x magnification. For the molecular analysis, dissection of the posterior part of the abdomen of each insect followed by DNA extraction and PCR amplification was performed using the TCZ1 (5' - CGA GCT CTT GCC CAC ACG GGT GCT - 3') and TCZ2 (5' - CCT CCA AGC AGC GGA TAG TTC AGG - 3') primers. Amplicons were chromatographed on a 2% agarose gel with a 100 bp size standard, stained with ethidium bromide and viewed with UV fluorescence.For both the microscopy and PCR assays, we calculated sensitivity (number of positives by a method divided by the number of positives by either method) and discrepancy (one method was negative and the other was positive) at the locality, life stage and habitat level. The degree of agreement between PCR and microscopy was determined by calculating Kappa (k) values with 95% confidence intervals. RESULTS: We observed a high prevalence of T. cruzi infection in T. infestans (81.16% by PCR and 56.52% by microscopy) and discovered that PCR is significantly more sensitive than microscopic observation. The overall degree of agreement between the two methods was moderate (Kappa = 0.43 +/- 0.07). The level of infection is significantly different among communities; however, prevalence was similar among habitats and life stages. CONCLUSION: PCR was significantly more sensitive than microscopy in all habitats, developmental stages and localities in Chuquisaca, Bolivia. Overall we observed a high prevalence of T. cruzi infection in T. infestans in this area of Bolivia; however, microscopy underestimated infection at all levels examined. [Abstract/Link to Full Text]

Wickham ME, Brown NF, Provias J, Finlay BB, Coombes BK
Oral infection of mice with Salmonella enterica serovar Typhimurium causes meningitis and infection of the brain.
BMC Infect Dis. 2007;765.
BACKGROUND: Salmonella meningitis is a rare and serious infection of the central nervous system following acute Salmonella enterica sepsis. For this pathogen, no appropriate model has been reported in which to examine infection kinetics and natural dissemination to the brain. METHODS: Five mouse lines including C57BL/6, Balb/c, 129S6-Slc11a1tm1Mcg, 129S1/SvImJ, B6.129-Inpp5dtm1Rkh were used in the murine typhoid model to examine the dissemination of systemic Salmonella enterica serovar Typhimurium following oral infection. RESULTS: We report data on spontaneous meningitis and brain infection following oral infection of mice with Salmonella enterica serovar Typhimurium. CONCLUSION: This model may provide a system in which dissemination of bacteria through the central nervous system and the influence of host and bacterial genetics can be queried. [Abstract/Link to Full Text]

Alam MM, Zaidi SZ, Malik SA, Naeem A, Shaukat S, Sharif S, Angez M, Khan A, Butt JA
Serology based disease status of Pakistani population infected with hepatitis B virus.
BMC Infect Dis. 2007;764.
BACKGROUND: The infection rate of hepatitis B virus is continuously increasing in Pakistan. Therefore, a comprehensive study of epidemiological data is the need of time. METHODS: A total of 1300 individuals were screened for HBV infection markers including HBsAg, anti-HBsAg, HBeAg and anti-HBcAg. The association of these disease indicators was compared with patients' epidemiological characteristics like age, socio-economic status and residential area to analyze and find out the possible correlation among these variables and the patients disease status. RESULTS: 52 (4%) individuals were found positive for HBsAg with mean age 23.5 +/- 3.7 years. 9.30%, 33.47% and 12% individuals had HBeAg, antibodies for HBsAg, and antibodies for HBcAg respectively. HBsAg seropositivity rate was significantly associated (p = 0.03) with the residing locality indicating high infection in rural areas. Antibodies titer against HBsAg decreased with the increasing age reflecting an inverse correlation. CONCLUSION: Our results indicate high prevalence rate of Hepatitis B virus infection and nationwide vaccination campaigns along with public awareness and educational programs are needed to be practiced urgently. [Abstract/Link to Full Text]

Graham SM, Baeten JM, Richardson BA, Bankson DD, Lavreys L, Ndinya-Achola JO, Mandaliya K, Overbaugh J, McClelland RS
Higher pre-infection vitamin E levels are associated with higher mortality in HIV-1-infected Kenyan women: a prospective study.
BMC Infect Dis. 2007;763.
BACKGROUND: Low vitamin E levels are often found in HIV-1 infection, and studies have suggested that higher levels may decrease the risk of disease progression. However, vitamin E supplementation has also been reported to increase CCR5 expression, which could increase HIV-1 replication. We hypothesized that vitamin E levels at HIV-1 acquisition may influence disease progression. METHODS: Vitamin E status was measured in stored samples from the last pre-infection visit for 67 Kenyan women with reliably estimated dates of HIV-1 acquisition. Regression analyses were used to estimate associations between pre-infection vitamin E and plasma viral load, time to CD4 count <200 cells/muL, and mortality. RESULTS: After controlling for potential confounding factors, each 1 mg/L increase in pre-infection vitamin E was associated with 0.08 log10 copies/mL (95% CI -0.01 to +0.17) higher set point viral load and 1.58-fold higher risk of mortality (95% CI 1.15-2.16). The association between higher pre-infection vitamin E and mortality persisted after adjustment for set point viral load (HR 1.55, 95% CI 1.13-2.13). CONCLUSION: Higher pre-infection vitamin E levels were associated with increased mortality. Further research is needed to elucidate the role vitamin E plays in HIV-1 pathogenesis. [Abstract/Link to Full Text]

Ranjbar R, Aleo A, Giammanco GM, Dionisi AM, Sadeghifard N, Mammina C
Genetic relatedness among isolates of Shigella sonnei carrying class 2 integrons in Tehran, Iran, 2002-2003.
BMC Infect Dis. 2007;762.
BACKGROUND: Shigella spp. are major cause of diarrhoeal disease in both developing and developed countries. Shigella sonnei is the serogroup of Shigella most frequently responsible for sporadic and epidemic enteritis in developed countries. In recent years the emergence and spread of S. sonnei biotype g carrying class 2 integron have been frequently reported in many countries. Recently, S. sonnei has been reported as the prevalent serogroup of Shigella in Iran.The present study was carried out to investigate phenotypic and genetic characteristics of Shigella sonnei isolates identified in the years 2002 and 2003 in Tehran, Iran. METHODS: Biotyping, drug susceptibility testing, pulsed field gel electrophoresis (PFGE) and analysis of class 2 integrons have been carried out on 60 S. sonnei isolates, including 57 sporadic isolates from paediatric cases of shigellosis occurring in 2002 and 2003, two sporadic isolates recovered in 1984 and the ATCC 9290 strain. RESULTS: Biotype g and resistance to streptomycin, sulfamethoxazole-trimethoprim and tetracycline were exhibited by 54 of the 57 recent isolates. Of the 54 biotype g isolates, 28 exhibited a class 2 integron of 2161 bp, and 24 a class 2 integron of 1371 bp, respectively. Class 2 integrons were not detected in four isolates only, including the two endemic isolates recovered in 1984 and two strains from recent sporadic cases. PFGE divided the strains into eight pulsotypes labeled A to H, three major pulsotypes - A to C - including the large majority of the recent sporadic S. sonnei isolates. Pulsotypes A and C were the most prevalent groups, accounting for 41.6% and 35.0%, respectively, of the isolates under study. CONCLUSION: The results suggest that biotype g, class 2 integron carrying S. sonnei are prevalent in our geographic area. S. sonnei isolated in the years 2002 and 2003 could be attributed to a few predominant clusters including, respectively, strains with pulsotypes B and C carrying a 2161 bp class 2 integron, and those having pulsotype A and a 1371 bp class 2 integron. A few epidemic clones are responsible for the apparently endemic occurrence of shigellosis in Tehran, Iran. [Abstract/Link to Full Text]

Eckstein BC, Adams DA, Eckstein EC, Rao A, Sethi AK, Yadavalli GK, Donskey CJ
Reduction of Clostridium Difficile and vancomycin-resistant Enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods.
BMC Infect Dis. 2007;761.
BACKGROUND: Contaminated environmental surfaces may play an important role in transmission of some healthcare-associated pathogens. In this study, we assessed the adequacy of cleaning practices in rooms of patients with Clostridium difficile-associated diarrhea (CDAD) and vancomycin-resistant Enterococcus (VRE) colonization or infection and examined whether an intervention would result in improved decontamination of surfaces. METHODS: During a 6-week period, we cultured commonly touched surfaces (i.e. bedrails, telephones, call buttons, door knobs, toilet seats, and bedside tables) in rooms of patients with CDAD and VRE colonization or infection before and after housekeeping cleaning, and again after disinfection with 10% bleach performed by the research staff. After the housekeeping staff received education and feedback, additional cultures were collected before and after housekeeping cleaning during a 10-week follow-up period. RESULTS: Of the 17 rooms of patients with VRE colonization or infection, 16 (94%) had one or more positive environmental cultures before cleaning versus 12 (71%) after housekeeping cleaning (p = 0.125), whereas none had positive cultures after bleach disinfection by the research staff (p < 0.001). Of the 9 rooms of patients with CDAD, 100% had positive cultures prior to cleaning versus 7 (78%) after housekeeping cleaning (p = 0.50), whereas only 1 (11%) had positive cultures after bleach disinfection by research staff (p = 0.031). After an educational intervention, rates of environmental contamination after housekeeping cleaning were significantly reduced. CONCLUSION: Our findings provide additional evidence that simple educational interventions directed at housekeeping staff can result in improved decontamination of environmental surfaces. Such interventions should include efforts to monitor cleaning and disinfection practices and provide feedback to the housekeeping staff. [Abstract/Link to Full Text]

Newell ML, Huang S, Fiore S, Thorne C, Mandelbrot L, Sullivan JL, Maupin R, Delke I, Watts DH, Gelber RD, Cunningham CK
Characteristics and management of HIV-1-infected pregnant women enrolled in a randomised trial: differences between Europe and the USA.
BMC Infect Dis. 2007;760.
BACKGROUND: Rates of mother-to-child transmission of HIV-1 (MTCT) have historically been lower in European than in American cohort studies, possibly due to differences in population characteristics. The Pediatric AIDS Clinical Trials Group Protocol (PACTG) 316 trial evaluated the effectiveness of the addition of intrapartum/neonatal nevirapine in reducing MTCT in women already receiving antiretroviral prophylaxis. Participation of large numbers of pregnant HIV-infected women from the US and Western Europe enrolling in the same clinical trial provided the opportunity to identify and explore differences in their characteristics and in the use of non-study interventions to reduce MTCT. METHODS: In this secondary analysis, 1350 women were categorized according to enrollment in centres in the USA (n = 978) or in Europe (n = 372). Factors associated with receipt of highly active antiretroviral therapy and with elective caesarean delivery were identified with logistic regression. RESULTS: In Europe, women enrolled were more likely to be white and those of black race were mainly born in Sub-Saharan Africa. Women in the US were younger and more likely to have previous pregnancies and miscarriages and a history of sexually transmitted infections.More than 90% of women did not report symptoms of their HIV infection; however, more women from the US had symptoms (8%), compared to women from Europe (4%). Women in the US were less likely to have HIV RNA levels <400 copies/ml at delivery than women enrolling in Europe, and more likely to receive highly active antiretroviral therapy, and to start therapy earlier in pregnancy. The elective caesarean delivery rate in Europe was 61%, significantly higher than that in the US (22%). Overall, 1.48% of infants were infected and there was no significant difference in the rate of transmission between Europe and the US despite the different approaches to treatment and delivery. CONCLUSION: These findings confirm that there are important historical differences between the HIV-infected pregnant populations in Western Europe and the USA, both in terms of the characteristics of the women and their obstetric and therapeutic management. Although highly active antiretroviral therapy predominates in pregnancy in both settings now, population differences are likely to remain. TRIAL REGISTRATION: NCT00000869. [Abstract/Link to Full Text]

Pérez-Farinós N, Ordobás M, García-Fernández C, García-Comas L, Cañellas S, Rodero I, Gutiérrez-Rodríguez A, García-Gutiérrez J, Ramírez R
Varicella and herpes zoster in Madrid, based on the Sentinel General Practitioner Network: 1997-2004.
BMC Infect Dis. 2007;759.
BACKGROUND: Varicella (chickenpox) is the primary disease caused by varicella-zoster virus. It is extremely contagious and is frequent in children. Indeed, in the absence of vaccination, a high proportion of the population is liable to contract it. Herpes zoster -more frequent among adults- is caused by reactivation of the latent virus. The objective of this study is to describe the status of and time trend for varicella and herpes zoster in the Madrid Autonomous Region prior to the introduction of the vaccine to the general population. METHODS: Data source: individualised varicella and herpes zoster case records kept by the Madrid Autonomous Region Sentinel General Practitioner Network for the period 1997-2004. Cumulative incidences, crude and standardised incidence rates, and age-specific rates of varicella and herpes zoster were calculated for each year. Kendall's Tau-b correlation coefficient was calculated to evaluate whether incidence displayed a time trend. Spectral density in the time series of weekly incidences was estimated using a periodogram. RESULTS: Standardised annual varicella incidence rates ranged from 742.5 (95% CI: 687.2-797.7) to 1239.6 (95% CI: 1164.5-1313.4) cases per 100 000 person-years. Most cases affected children, though complications were more frequent in adults. Varicella incidence displayed an annual periodicity but no trend over time. Most herpes zoster cases occurred at advanced ages, with incidence registering a rising annual trend but no seasonality factor. CONCLUSION: In the absence of vaccination, no significant changes in varicella incidence were in evidence recent years, though these were observed in the incidence of herpes zoster. Sentinel general practitioner networks are a valid instrument for surveillance of diseases such as varicella. Further varicella vaccination-coverage and vaccine-efficacy studies are called for. [Abstract/Link to Full Text]

Haq JA, Khan MA, Afroze N, Haq T
Localized primary renal aspergillosis in a diabetic patient following lithotripsy--a case report.
BMC Infect Dis. 2007;758.
BACKGROUND: Primary renal aspergillosis is rare in diabetic patients. Diagnosis of localized primary renal Aspergillus infection in diabetic patients requires careful investigations due to its benign presentation and lack of associated systemic clinical features. There is also paucity of information on the role of conservative treatment of such localized infection with antifungal agents only. Here, we describe a case of localized renal aspergillosis in a type 2 diabetic patient with a brief review of literature. CASE PRESENTATION: We describe a case of unilateral renal aspergillosis following intracorporeal pneumatic lithotripsy (ICPL) in a type 2 diabetic man. The patient presented with mild pain in the left lumbar region and periodic expulsion of whitish soft masses per urethra, which yielded growth of Aspergillus fumigatus. He was treated initially with amphotericin B; however, it was stopped after 2 weeks, as he could not tolerate the drug. Subsequently, he was successfully treated with oral itraconazole. CONCLUSION: Localized renal aspergillosis may be suspected in diabetic patients having history of urinary tract instrumentation, mild lumbar pain, passage of suspicious masses in urine and persistent pyuria. Examination of the suspicious substances expelled per urethra is essential for diagnosis as routine multiple urine analysis may yield negative results. Conservative treatment with oral itraconazole alone is effective in cases with incomplete obstruction. [Abstract/Link to Full Text]

Jonasson A, Eriksson C, Jenkinson HF, Källestål C, Johansson I, Strömberg N
Innate immunity glycoprotein gp-340 variants may modulate human susceptibility to dental caries.
BMC Infect Dis. 2007;757.
BACKGROUND: Bacterial adhesion is an important determinant of colonization and infection, including dental caries. The salivary scavenger receptor cysteine-rich glycoprotein gp-340, which mediates adhesion of Streptococcus mutans (implicated in caries), harbours three major size variants, designated gp-340 I to III, each specific to an individual saliva. Here we have examined the association of the gp-340 I to III polymorphisms with caries experience and adhesion of S. mutans. METHODS: A case-referent study was performed in 12-year-old Swedish children with high (n = 19) or low (n = 19) caries experiences. We measured the gp-340 I to III saliva phenotypes and correlated those with multiple outcome measures for caries experience and saliva adhesion of S. mutans using the partial least squares (PLS) multivariate projection technique. In addition, we used traditional statistics and 2-year caries increment to verify the established PLS associations, and bacterial adhesion to purified gp-340 I to III proteins to support possible mechanisms. RESULTS: All except one subject were typed as gp-340 I to III (10, 23 and 4, respectively). The gp-340 I phenotype correlated positively with caries experience (VIP = 1.37) and saliva adhesion of S. mutans Ingbritt (VIP = 1.47). The gp-340 II and III phenotypes tended to behave in the opposite way. Moreover, the gp-340 I phenotype tended to show an increased 2-year caries increment compared to phenotypes II/III. Purified gp-340 I protein mediated markedly higher adhesion of S. mutans strains Ingbritt and NG8 and Lactococcus lactis expressing AgI/II adhesins (SpaP or PAc) compared to gp-340 II and III proteins. In addition, the gp-340 I protein appeared over represented in subjects positive for Db, an allelic acidic PRP variant associated with caries, and subjects positive for both gp-340 I and Db tended to experience more caries than those negative for both proteins. CONCLUSION: Gp-340 I behaves as a caries susceptibility protein. [Abstract/Link to Full Text]

Wang TK, Wong SS
Streptobacillus moniliformis septic arthritis: a clinical entity distinct from rat-bite fever?
BMC Infect Dis. 2007;756.
BACKGROUND: Streptobacillus moniliformis is a zoonotic agent associated with rodent contacts. Although it is more commonly reported to cause rat-bite fever with reactive arthritides, it can also lead to pyogenic infection of the joints. CASE PRESENTATION: We present a lady with past history of osteoarthritis developing streptobacillary septic arthritides of the right knee and left wrist, and required antibiotic and arthrotomy for treatment. We also review 11 previously reported cases of streptobacillary septic arthritis to discuss the characteristics, treatment, prognosis of the infection, and illustrates the differences between streptobacillary rat-bite fever and septic arthritis. Among this patient population, most patients had potential contact with rats (91.6%). The knee is the most commonly affected joint (58.3%), and 83.3% patients having polyarticular involvement. As opposed to rat-bite fever, fever and rash was only present in 58.3% and 16.7% of patients respectively. S. moniliformis bacteremia is uncommon (8.4%) and the prognosis is good. CONCLUSION: Arthrocentesis is useful in distinguishing streptobacillary septic arthritis from reactive arthritis of rat-bite fever. The sole use of commercial media containing sodium polyanethol sulfonate may render the bacterial culture negative. A detailed history of possible exposure to rodents should be elicited from patients with arthritis in order to facilitate microbiologic diagnosis. [Abstract/Link to Full Text]


Recent Articles in BMC Microbiology

Brillard J, Lereclus D
Characterization of a small PlcR-regulated gene co-expressed with cereolysin O.
BMC Microbiol. 2007;752.
BACKGROUND: In the human pathogen Bacillus cereus, the expression of most extracellular virulence factors is controlled by the transcriptional activator PlcR. Among these virulence factors, cereolysin O (Clo) is an haemolysin belonging to the cholesterol-dependant cytolysins, a protein family extensively studied in Gram-positive bacteria. RESULTS: In the genomes of bacteria belonging to the B. cereus group, including Bacillus anthracis and Bacillus thuringiensis, a small gene encoding a 26-amino acid peptide was present in multicopy. One copy was always found upstream from the gene encoding Clo. In B. cereus ATCC 14579, the small gene and the clo gene are co-transcribed. Transcriptional fusions showed that the three paralogues identified in this strain were expressed in a PlcR-dependent manner. We propose to name these peptides Spp for small PlcR-regulated peptides. We show that a synthetic peptide corresponding to the deduced product of the spp genes displayed antibacterial activity. CONCLUSION: The co-expression of spp, a small PlcR-regulated multicopy gene with clo suggests a yet unidentified relationship between Spp and the cholesterol-dependent cytolysin in bacteria belonging to the B.cereus group. [Abstract/Link to Full Text]

Kibiki GS, Mulder B, Dolmans WM, de Beer JL, Boeree M, Sam N, van Soolingen D, Sola C, van der Zanden AG
M. tuberculosis genotypic diversity and drug susceptibility pattern in HIV-infected and non-HIV-infected patients in northern Tanzania.
BMC Microbiol. 2007;751.
BACKGROUND: Tuberculosis (TB) is a major health problem and HIV is the major cause of the increase in TB. Sub-Saharan Africa is endemic for both TB and HIV infection. Determination of the prevalence of M. tuberculosis strains and their drug susceptibility is important for TB control.TB positive culture, BAL fluid or sputum samples from 130 patients were collected and genotyped. The spoligotypes were correlated with anti-tuberculous drug susceptibility in HIV-infected and non-HIV patients from Tanzania. RESULTS: One-third of patients were TB/HIV co-infected. Forty-seven spoligotypes were identified.Fourteen isolates (10.8%) had new and unique spoligotypes while 116 isolates (89.2%) belonged to 33 known spoligotypes. The major spoligotypes contained nine clusters: CAS1-Kili 30.0%, LAM11- ZWE 14.6%, ND 9.2%, EAI 6.2%, Beijing 5.4%, T-undefined 4.6%, CAS1-Delhi 3.8%, T1 3.8% and LAM9 3.8%. Twelve (10.8%) of the 111 phenotypically tested strains were resistant to anti-TB drugs. Eight (7.2%) were monoresistant strains: 7 to isoniazid (INH) and one to streptomycin. Four strains (3.5%) were resistant to multiple drugs: one (0.9%) was resistant to INH and streptomycin and the other three (2.7%) were MDR strains: one was resistant to INH, rifampicin and ethambutol and two were resistant to all four anti-TB drugs. Mutation in the katG gene codon 315 and the rpoB hotspot region showed a low and high sensitivity, respectively, as predictor of phenotypic drug resistance. CONCLUSION: CAS1-Kili and LAM11-ZWE were the most common families. Strains of the Beijing family and CAS1-Kili were not or least often associated with resistance, respectively. HIV status was not associated with spoligotypes, resistance or previous TB treatment. [Abstract/Link to Full Text]

Parker CT, Miller WG, Horn ST, Lastovica AJ
Common genomic features of Campylobacter jejuni subsp. doylei strains distinguish them from C. jejuni subsp. jejuni.
BMC Microbiol. 2007;750.
BACKGROUND: Campylobacter jejuni has been divided into two subspecies: C. jejuni subsp. jejuni (Cjj) and C. jejuni subsp. doylei (Cjd). Nearly all of the C. jejuni strains isolated are Cjj; nevertheless, although Cjd strains are isolated infrequently, they differ from Cjj in two key aspects: they are obtained primarily from human clinical samples and are associated often with bacteremia, in addition to gastroenteritis. In this study, we utilized multilocus sequence typing (MLST) and a DNA microarray-based comparative genomic indexing (CGI) approach to examine the genomic diversity and gene content of Cjd strains. RESULTS: A geographically diverse collection of eight Cjd strains was examined by MLST and determined to be phylogenetically distinct from Cjj strains. Microarray-based CGI approach also supported this. We were able to demonstrate that Cjd strains exhibited divergence from Cjj strains NCTC 11168 and RM1221 in many of the intraspecies hypervariable regions. Moreover, multiple metabolic, transport and virulence functions (e.g. cytolethal distending toxin) were shown to be absent in the Cjd strains examined. CONCLUSION: Our data demonstrate that Cjd are phylogenetically distinct from Cjj strains. Using the CGI approach, we identified subsets of absent genes from amongst the C. jejuni genes that provide clues as to the potential evolutionary origin and unusual pathogenicity of Cjd. [Abstract/Link to Full Text]

Kleinschmidt MC, Michaelis M, Ogbomo H, Doerr HW, Cinatl J
Inhibition of apoptosis prevents West Nile virus induced cell death.
BMC Microbiol. 2007;749.
BACKGROUND: West Nile virus (WNV) infection can cause severe meningitis and encephalitis in humans. Apoptosis was recently shown to contribute to the pathogenesis of WNV encephalitis. Here, we used WNV-infected glioma cells to study WNV-replication and WNV-induced apoptosis in human brain-derived cells. RESULTS: T98G cells are highly permissive for lytic WNV-infection as demonstrated by the production of infectious virus titre and the development of a characteristic cytopathic effect. WNV replication decreased cell viability and induced apoptosis as indicated by the activation of the effector caspase-3, the initiator caspases-8 and -9, poly(ADP-ribose)polymerase (PARP) cleavage and the release of cytochrome c from the mitochondria. Truncation of BID indicated cross-talk between the extrinsic and intrinsic apoptotic pathways. Inhibition of the caspases-8 or -9 inhibited PARP cleavage, demonstrating that both caspases are involved in WNV-induced apoptosis. Pan-caspase inhibition prevented WNV-induced apoptosis without affecting virus replication. CONCLUSION: We found that WNV infection induces cell death in the brain-derived tumour cell line T98G by apoptosis under involvement of constituents of the extrinsic as well as the intrinsic apoptotic pathways. Our results illuminate the molecular mechanism of WNV-induced neural cell death. [Abstract/Link to Full Text]

Rolain JM, Fenollar F, Raoult D
False positive PCR detection of Tropheryma whipplei in the saliva of healthy people.
BMC Microbiol. 2007;748.
BACKGROUND: Tropheryma whipplei, the agent of Whipple's disease (WD), has been recently isolated and the genomes of two isolates have been fully sequenced. Previous diagnosis tools for the diagnosis of the disease used sequence analysis of the 16S rRNA gene. Using this target gene, the high percentage of detection of the bacterium in saliva of healthy people was in contrast to the negative results obtained with specific target genes. The aim of our study was to compare previously published primers targeting the 16S rRNA gene to real-time PCR with Taqman* probes targeting specific repeat genes only found in the genome of T. whipplei in a series of 57 saliva from healthy people. RESULTS: Although the specific real-time PCR assays with both primers and probes were negative for all the samples, 13 out of 57 samples were positive with different primers previously reported targeting the 16S rRNA gene. Among the positive samples, 8 yielded a 231-bp sequence that was 99.1% identical to that of Actinomyces odontolyticus, 2 yielded a 226-bp that was 99.6% identical to that of A. turicensis, and 3 yielded a 160-bp sequence that was 98.5% identical to that of Capnocytophaga gingivalis. We found that the C. gingivalis and A. odontolyticus 16S rRNA sequences obtained in our study share more than 80% homology with the corresponding 16S rRNA sequences of the T. whipplei genomes especially at 5' and 3' end. CONCLUSION: Asymptomatic carriers of T. whipplei in saliva may exist but their prevalence is much lower than those previously reported. Testing the specificity of designed primers is critical to avoid false positive detection of T. whipplei. In atypical case we recommend to test two different specific target genes before concluding. [Abstract/Link to Full Text]

Khairnar K, Parija SC
A novel nested multiplex polymerase chain reaction (PCR) assay for differential detection of Entamoeba histolytica, E. moshkovskii and E. dispar DNA in stool samples.
BMC Microbiol. 2007;747.
BACKGROUND: E. histolytica, a pathogenic amoeba, is indistinguishable in its cyst and trophozoite stages from those of non-pathogenic E. moshkovskii and E. dispar by light microscopy. We have developed a nested multiplex PCR targeting a 16S-like rRNA gene for differential detection of all the three morphologically similar forms of E. histolytica, E. moshkovskii and E. dispar simultaneously in stool samples. RESULTS: The species specific product size for E. histolytica, E. moshkovskii and E. dispar was 439, 553 and 174 bp respectively, which was clearly different for all the three Entamoeba species. The nested multiplex PCR showed a sensitivity of 94% and specificity of 100% for the demonstration of E. histolytica, E. moshkovskii and E. dispar DNA in stool samples. The PCR was positive for E. histolytica, E. moshkovskii and E. dispar in a total of 190 out of 202 stool specimens (94% sensitive) that were positive for E. histolytica/E. dispar/E. moshkovskii by examination of stool by microscopy and/or culture. All the 35 negative control stool samples that were negative for E. histolytica/E. dispar/E. moshkovskii by microscopy and culture were also found negative by the nested multiplex PCR (100% specific). The result from the study shows that only 34.6% of the patient stool samples that were positive for E. histolytica/E. dispar/E. moshkovskii by examination of stool by microscopy and/or culture, were actually positive for pathogenic E. histolytica and the remaining majority of the stool samples were positive for non-pathogenic E. dispar or E. moshkovskii as demonstrated by the use of nested multiplex PCR. CONCLUSION: The present study reports a new nested multiplex PCR strategy for species specific detection and differentiation of E. histolytica, E. dispar and E. moshkovskii DNA in stool specimens. The test is highly specific, sensitive and also rapid, providing the results within 12 hours of receiving stool specimens. [Abstract/Link to Full Text]

Brigante GR, Luzzaro FA, Pini B, Lombardi G, Sokeng G, Toniolo AQ
Drug susceptibility testing of clinical isolates of streptococci and enterococci by the Phoenix automated microbiology system.
BMC Microbiol. 2007;746.
BACKGROUND: Drug resistance is an emerging problem among streptococcal and enterococcal species. Automated diagnostic systems for species identification and antimicrobial susceptibility testing (AST) have become recently available. We evaluated drug susceptibility of clinical isolates of streptococci and enterococci using the recent Phoenix system (BD, Sparks, MD). Diagnostic tools included the new SMIC/ID-2 panel for streptococci, and the PMIC/ID-14 for enterococci. Two-hundred and fifty isolates have been investigated: beta-hemolytic streptococci (n = 65), Streptococcus pneumoniae (n = 50), viridans group streptococci (n = 32), Enterococcus faecium (n = 40), Enterococcus faecalis (n = 43), other catalase-negative cocci (n = 20). When needed, species ID was determined using molecular methods. Test bacterial strains were chosen among those carrying clinically-relevant resistance determinants (penicillin, macrolides, fluoroquinolones, glycopeptides). AST results of the Phoenix system were compared to minimal inhibitory concentration (MIC) values measured by the Etest method (AB Biodisk, Solna, Sweden). RESULTS: Streptococci: essential agreement (EA) and categorical agreement (CA) were 91.9% and 98.8%, respectively. Major (ME) and minor errors (mE) accounted for 0.1% and 1.1% of isolates, respectively. No very major errors (VME) were produced. Enterococci: EA was 97%, CA 96%. Small numbers of VME (0.9%), ME (1.4%) and mE (2.8%) were obtained. Overall, EA and CA rates for most drugs were above 90% for both genera. A few VME were found: a) teicoplanin and high-level streptomycin for E. faecalis, b) high-level gentamicin for E. faecium. The mean time to results (+/- SD) was 11.8 +/- 0.9 h, with minor differences between streptococci and enterococci. CONCLUSION: The Phoenix system emerged as an effective tool for quantitative AST. Panels based on dilution tests provided rapid and accurate MIC values with regard to clinically-relevant streptococcal and enterococcal species. [Abstract/Link to Full Text]

Fothergill JL, Panagea S, Hart CA, Walshaw MJ, Pitt TL, Winstanley C
Widespread pyocyanin over-production among isolates of a cystic fibrosis epidemic strain.
BMC Microbiol. 2007;745.
BACKGROUND: Some isolates of the Liverpool cystic fibrosis epidemic strain of Pseudomonas aeruginosa exhibit an unusual virulence-related phenotype, characterized by over-production of quorum sensing-regulated exoproducts such as pyocyanin and LasA protease. Our aim was to determine the prevalence of this unusual phenotype amongst isolates of the epidemic strain, and to study other intraclonal phenotypic and genotypic variations. RESULTS: The unusual phenotype was detected in at least one epidemic strain isolate from the majority of cystic fibrosis patients tested, and can be retained for up to seven years during chronic infection. Multiple sequential isolates of the epidemic strain taken from six patients over a period of up to nine years exhibited a wide range of phenotypes, including different antimicrobial susceptibilities. Our data suggest that each sputum sample contains a mixture of phenotypes and genotypes within the epidemic strain population, including within colony morphotypes. Many isolates exhibit premature (during early rather than late exponential growth) and over-production of pyocyanin, which has a number of toxic effects directly relevant to cystic fibrosis. CONCLUSION: The widespread occurrence of this unusual phenotype suggests that it may play an important role in the success of the epidemic strain. [Abstract/Link to Full Text]

Hitchcock RA, Thomas S, Campbell DA, Sturm NR
The promoter and transcribed regions of the Leishmania tarentolae spliced leader RNA gene array are devoid of nucleosomes.
BMC Microbiol. 2007;744.
BACKGROUND: The spliced leader (SL) RNA provides the 5' m7G cap and first 39 nt for all nuclear mRNAs in kinetoplastids. This small nuclear RNA is transcribed by RNA polymerase II from individual promoters. In Leishmania tarentolae the SL RNA genes reside in two multi-copy tandem arrays designated MINA and MINB. The transcript accumulation from the SL promoter on the drug-selected, episomal SL RNA gene cassette pX-tSL is ~10% that of the genomic array in uncloned L. tarentolae transfectants. This disparity is neither sequence- nor copy-number related, and thus may be due to interference of SL promoter function by epigenetic factors. To explore these possibilities we examined the nucleoplasmic localization of the SL RNA genes as well as their nucleosomal architecture. RESULTS: The genomic SL RNA genes and the episome did not co-localize within the nucleus. Each genomic repeat contains one nucleosome regularly positioned within the non-transcribed intergenic region. The 363-bp MINA array was resistant to micrococcal nuclease digestion between the -258 and -72 positions relative to the transcription start point due to nucleosome association, leaving the promoter elements and the entire transcribed region exposed for protein interactions. A pattern of ~164-bp protected segments was observed, corresponding to the amount of DNA typically bound by a nucleosome. By contrast, nucleosomes on the pX-tSL episome were randomly distributed over the episomal SL cassette, reducing transcription factor access to the episomal promoter by approximately 74%. Cloning of the episome transfectants revealed a range of transcriptional activities, implicating a mechanism of epigenetic heredity. CONCLUSION: The disorganized nucleosomes on the pX episome are in a permissive conformation for transcription of the SL RNA cassette approximately 25% of the time within a given parasite. Nucleosome interference is likely the major factor in the apparent transcriptional repression of the SL RNA gene cassette. Coupled with the requirement for run-around transcription that drives expression of the selectable drug marker, transcription of the episomal SL may be reduced even further due to sub-optimal nucleoplasmic localization and initiation complex disruption. [Abstract/Link to Full Text]

Fagerlund A, Brillard J, Fürst R, Guinebretière MH, Granum PE
Toxin production in a rare and genetically remote cluster of strains of the Bacillus cereus group.
BMC Microbiol. 2007;743.
BACKGROUND: Three enterotoxins are implicated in diarrhoeal food poisoning due to Bacillus cereus: Haemolysin BL (Hbl), Non-haemolytic enterotoxin (Nhe), and Cytotoxin K (CytK). Toxin gene profiling and assays for detection of toxin-producing stains have been used in attempts to evaluate the enterotoxic potential of B. cereus group strains. B. cereus strain NVH 391/98, isolated from a case of fatal enteritis, was genetically remote from other B. cereus group strains. This strain lacked the genes encoding Hbl and Nhe, but contains CytK-1. The high virulence of this strain is thought to be due to the greater cytotoxic activity of CytK-1 compared to CytK-2, and to a high level of cytK expression. To date, only three strains containing cytK-1 have been identified; B. cereus strains NVH 391/98, NVH 883/00, and INRA AF2. RESULTS: A novel gene variant encoding Nhe was identified in these three strains, which had an average of 80% identity in protein sequence with previously identified Nhe toxins. While culture supernatants containing CytK and Nhe from NVH 391/98 and INRA AF2 were highly cytotoxic, NVH 883/00 expressed little or no CytK and Nhe and was non-cytotoxic. Comparative sequence and expression studies indicated that neither the PlcR/PapR quorum sensing system, nor theYvrGH and YvfTU two-component systems, were responsible for the observed difference in toxin production. Additionally, phylogenetic analysis of 13 genes showed that NVH 391/98, NVH 883/00, and INRA AF2 comprise a novel cluster of strains genetically distant from other B. cereus group strains. CONCLUSION: Due to its divergent sequence, the novel nhe operon had previously not been detected in NVH 391/98 using PCR and several monoclonal antibodies. Thus, toxigenic profiling based on the original nhe sequence will fail to detect the toxin in this group of strains. The observation that strain NVH 883/00 carries cytK-1 but is non-cytotoxic indicates that the detection of this gene variant is not a sufficient criterion for identification of highly cytotoxic strains. The presence of the novel nhe operon and the cytK-1 gene variant in this cluster of strains reflect their phylogenetically remote relationship towards other B. cereus group strains. [Abstract/Link to Full Text]

Lee J, Jayaraman A, Wood TK
Indole is an inter-species biofilm signal mediated by SdiA.
BMC Microbiol. 2007;742.
BACKGROUND: As a stationary phase signal, indole is secreted in large quantities into rich medium by Escherichia coli and has been shown to control several genes (e.g., astD, tnaB, gabT), multi-drug exporters, and the pathogenicity island of E. coli; however, its impact on biofilm formation has not been well-studied. RESULTS: Through a series of global transcriptome analyses, confocal microscopy, isogenic mutants, and dual-species biofilms, we show here that indole is a non-toxic signal that controls E. coli biofilms by repressing motility, inducing the sensor of the quorum sensing signal autoinducer-1 (SdiA), and influencing acid resistance (e.g., hdeABD, gadABCEX). Isogenic mutants showed these associated proteins are directly related to biofilm formation (e.g., the sdiA mutation increased biofilm formation 50-fold), and SdiA-mediated transcription was shown to be influenced by indole. The reduction in motility due to indole addition results in the biofilm architecture changing from scattered towers to flat colonies. Additionally, there are 12-fold more E. coli cells in dual-species biofilms grown in the presence of Pseudomonas cells engineered to express toluene o-monooxygenase (TOM, which converts indole to an insoluble indigoid) than in biofilms with pseudomonads that do not express TOM due to a 22-fold reduction in extracellular indole. Also, indole stimulates biofilm formation in pseudomonads. Further evidence that the indole effects are mediated by SdiA and homoserine lactone quorum sensing is that the addition of N-butyryl-, N-hexanoyl-, and N-octanoyl-L-homoserine lactones repress E. coli biofilm formation in the wild-type strain but not with the sdiA mutant. CONCLUSION: Indole is an interspecies signal that decreases E. coli biofilms through SdiA and increases those of pseudomonads. Indole may be manipulated to control biofilm formation by oxygenases of bacteria that do not synthesize it in a dual-species biofilm. Furthermore, E. coli changes its biofilm in response to signals it cannot synthesize (homoserine lactones), and pseudomonads respond to signals they do not synthesize (indole). [Abstract/Link to Full Text]

Parija SC, Khairnar K
Detection of excretory Entamoeba histolytica DNA in the urine, and detection of E. histolytica DNA and lectin antigen in the liver abscess pus for the diagnosis of amoebic liver abscess.
BMC Microbiol. 2007;741.
BACKGROUND: Amoebic liver abscess (ALA) and pyogenic liver abscesses (PLA) appear identical by ultrasound and other imaging techniques. Collection of blood or liver abscess pus for diagnosis of liver abscesses is an invasive procedure, and the procedure requires technical expertise and disposable syringes. Collection of urine is a noninvasive procedure. Therefore, there has been much interest shown towards the use of urine as an alternative clinical specimen for the diagnosis of some parasitic infections. Here, we report for the first time the detection of E. histolytica DNA excreted in the urine for diagnosis of the cases of ALA. RESULTS: E. histolytica DNA was detected in liver abscess pus specimen of 80.4% of ALA patients by a nested multiplex polymerase chain reaction (PCR) targeting 16S-like r RNA gene. The nested PCR detected E. histolytica DNA in all 37 (100%) liver abscess pus specimens collected prior to metronidazole treatment, but were detected in only 53 of 75 (70.6%) pus specimens collected after therapy with metronidazole. Similarly, the PCR detected E. histolytica DNA in 21 of 53 (39.6%) urine specimens of ALA patients. The test detected E. histolytica DNA in only 4 of 23 (17.4%) urine specimens collected prior to metronidazole treatment, but were detected in 17 of 30 (56.7%) urine specimens collected after treatment with metronidazole. The enzyme-linked immunosorbent assay (ELISA) for the detection of lectin E. histolytica antigen in the liver abscess pus showed a sensitivity of 50% and the indirect haemagglutination (IHA) test for detection of amoebic antibodies in the serum showed a sensitivity of 76.8% for the diagnosis of the ALA. CONCLUSION: The present study for the first time shows that the kidney barrier in ALA patients is permeable to E. histolytica DNA molecule resulting in excretion of E. histolytica DNA in urine which can be detected by PCR. The study also shows that the PCR for detection of E. histolytica DNA in urine of patients with ALA can also be used as a prognostic marker to assess the course of the diseases following therapy by metronidazole. The detection of E. histolytica DNA in urine specimen of ALA patients provides a new approach for the diagnosis of ALA. [Abstract/Link to Full Text]

Strych U, Davlieva M, Longtin JP, Murphy EL, Im H, Benedik MJ, Krause KL
Purification and preliminary crystallization of alanine racemase from Streptococcus pneumoniae.
BMC Microbiol. 2007;740.
BACKGROUND: Over the past fifteen years, antibiotic resistance in the Gram-positive opportunistic human pathogen Streptococcus pneumoniae has significantly increased. Clinical isolates from patients with community-acquired pneumonia or otitis media often display resistance to two or more antibiotics. Given the need for new therapeutics, we intend to investigate enzymes of cell wall biosynthesis as novel drug targets. Alanine racemase, a ubiquitous enzyme among bacteria and absent in humans, provides the essential cell wall precursor, D-alanine, which forms part of the tetrapeptide crosslinking the peptidoglycan layer. RESULTS: The alanine racemases gene from S. pneumoniae (alrSP) was amplified by PCR and cloned and expressed in Escherichia coli. The 367 amino acid, 39854 Da dimeric enzyme was purified to electrophoretic homogeneity and preliminary crystals were obtained. Racemic activity was demonstrated through complementation of an alr auxotroph of E. coli growing on L-alanine. In an alanine racemases photometric assay, specific activities of 87.0 and 84.8 U mg-1 were determined for the conversion of D- to L-alanine and L- to D-alanine, respectively. CONCLUSION: We have isolated and characterized the alanine racemase gene from the opportunistic human pathogen S. pneumoniae. The enzyme shows sufficient homology with other alanine racemases to allow its integration into our ongoing structure-based drug design project. [Abstract/Link to Full Text]

Nouvel LX, Dos Vultos T, Kassa-Kelembho E, Rauzier J, Gicquel B
A non-sense mutation in the putative anti-mutator gene ada/alkA of Mycobacterium tuberculosis and M. bovis isolates suggests convergent evolution.
BMC Microbiol. 2007;739.
BACKGROUND: Previous studies have suggested that variations in DNA repair genes of W-Beijing strains may have led to transient mutator phenotypes which in turn may have contributed to host adaptation of this strain family. Single nucleotide polymorphism (SNP) in the DNA repair gene mutT1 was identified in MDR-prone strains from the Central African Republic. A Mycobacteriumtuberculosis H37Rv mutant inactivated in two DNA repair genes, namely ada/alkA and ogt, was shown to display a hypermutator phenotype. We then looked for polymorphisms in these genes in Central African Republic strains (CAR). RESULTS: In this study, 55 MDR and 194 non-MDR strains were analyzed. Variations in DNA repair genes ada/alkA and ogt were identified. Among them, by comparison to M. tuberculosis published sequences, we found a non-sense variation in ada/alkA gene which was also observed in M. bovis AF2122 strain. SNPs that are present in the adjacent regions to the amber variation are different in M. bovis and in M. tuberculosis strain. CONCLUSION: An Amber codon was found in the ada/alkA locus of clustered M. tuberculosis isolates and in M. bovis strain AF2122. This is likely due to convergent evolution because SNP differences between strains are incompatible with horizontal transfer of an entire gene. This suggests that such a variation may confer a selective advantage and be implicated in hypermutator phenotype expression, which in turn contributes to adaptation to environmental changes. [Abstract/Link to Full Text]

Luo J, Liu G, Zhong Y, Jia T, Liu K, Chen D, Zhong G
Characterization of hypothetical proteins Cpn0146, 0147, 0284 & 0285 that are predicted to be in the Chlamydia pneumoniae inclusion membrane.
BMC Microbiol. 2007;738.
BACKGROUND: Although more than 100 Chlamydia pneumoniae hypothetical proteins have been predicted to be inclusion membrane proteins, only a few have been experimentally demonstrated to be in the inclusion membrane. Using antibodies raised with fusion proteins, we characterized four such hypothetical proteins encoded by two gene clusters (Cpn0146-147 and Cpn0284-285) in the C. pneumoniae genome. RESULTS: Cpn0146 and 0147 were detected in the inclusion membrane while Cpn0284 and 0285 inside inclusion and mainly associated with reticulate bodies although all four proteins contain an N-terminal bi-lobed hydrophobic region, a signature motif assigned to inclusion membrane proteins. These four hypothetical proteins were only detected in cells infected with C. pneumoniae but not other chlamydial species, with Cpn0147 at 6 hours and Cpn0146, 0284 & 0285 at 24 hours after infection. Cpn0146 & 147 but not Cpn0284 and 285 co-localized with a host cell endoplasmic reticulum marker, a property known to be possessed by some chlamydial inclusion membrane proteins, when expressed in the host cell cytosol via transgenes. However, the endoplasmic reticulum localization of the C. pneumoniae inclusion membrane proteins did not result in inhibition of the subsequent C. pneumoniae infection. CONCLUSION: The hypothetical proteins Cpn0146 & 0147 were localized in the C. pneumoniae inclusion membrane while Cpn0284 & 0285 within the inclusion although all four were predicted to be Inc proteins, suggesting the need to experimentally characterize the predicted Inc proteins. [Abstract/Link to Full Text]

Fu LM, Fu-Liu CS
The gene expression data of Mycobacterium tuberculosis based on Affymetrix gene chips provide insight into regulatory and hypothetical genes.
BMC Microbiol. 2007;737.
BACKGROUND: Tuberculosis remains a leading infectious disease with global public health threat. Its control and management have been complicated by multi-drug resistance and latent infection, which prompts scientists to find new and more effective drugs. With the completion of the genome sequence of the etiologic bacterium, Mycobacterium tuberculosis, it is now feasible to search for new drug targets by sieving through a large number of gene products and conduct genome-scale experiments based on microarray technology. However, the full potential of genome-wide microarray analysis in configuring interrelationships among all genes in M. tuberculosis has yet to be realized. To date, it is only possible to assign a function to 52% of proteins predicted in the genome. RESULTS: We conducted a functional-genomics study using the high-resolution Affymetrix oligonucleotide GeneChip. Approximately one-half of the genes were found to be always expressed, including more than 100 predicted conserved hypotheticals, in the genome of M. tuberculosis during the log phase of in vitro growth. The gene expression profiles were analyzed and visualized through cluster analysis to epitomize the full details of genomic behavior. Broad patterns derived from genome-wide expression experiments in this study have provided insight into the interrelationships among genes in the basic cellular processes of M. tuberculosis. CONCLUSION: Our results have confirmed several known gene clusters in energy production, information pathways, and lipid metabolism, and also hinted at potential roles of hypothetical and regulatory proteins. [Abstract/Link to Full Text]

Habimana O, Le Goff C, Juillard V, Bellon-Fontaine MN, Buist G, Kulakauskas S, Briandet R
Positive role of cell wall anchored proteinase PrtP in adhesion of lactococci.
BMC Microbiol. 2007;736.
BACKGROUND: The first step in biofilm formation is bacterial attachment to solid surfaces, which is dependent on the cell surface physico-chemical properties. Cell wall anchored proteins (CWAP) are among the known adhesins that confer the adhesive properties to pathogenic Gram-positive bacteria. To investigate the role of CWAP of non-pathogen Gram-positive bacteria in the initial steps of biofilm formation, we evaluated the physico-chemical properties and adhesion to solid surfaces of Lactococcus lactis. To be able to grow in milk this dairy bacterium expresses a cell wall anchored proteinase PrtP for breakdown of milk caseins. RESULTS: The influence of the anchored cell wall proteinase PrtP on microbial surface physico-chemical properties, and consequently on adhesion, was evaluated using lactococci carrying different alleles of prtP. The presence of cell wall anchored proteinase on the surface of lactococcal cells resulted in an increased affinity to solvents with different physico-chemical properties (apolar and Lewis acid-base solvents). These properties were observed regardless of whether the PrtP variant was biologically active or not, and were not observed in strains without PrtP. Anchored PrtP displayed a significant increase in cell adhesion to solid glass and tetrafluoroethylene surfaces. CONCLUSION: Obtained results indicate that exposure of an anchored cell wall proteinase PrtP, and not its proteolytic activity, is responsible for greater cell hydrophobicity and adhesion. The increased bacterial affinity to polar and apolar solvents indicated that exposure of PrtP on lactococcal cell surface could enhance the capacity to exchange attractive van der Waals interactions, and consequently increase their adhesion to different types of solid surfaces and solvents. [Abstract/Link to Full Text]

Laín A, Elguezabal N, Brena S, García-Ruiz JC, Del Palacio A, Moragues MD, Pontón J
Diagnosis of invasive candidiasis by enzyme-linked immunosorbent assay using the N-terminal fragment of Candida albicans hyphal wall protein 1.
BMC Microbiol. 2007;735.
BACKGROUND: The diagnosis of invasive candidiasis is difficult because there are no specific clinical manifestations of the disease and colonization and infection are difficult to distinguish. In the last decade, much effort has been made to develop reliable tests for rapid diagnosis of invasive candidiasis, but none of them have found widespread clinical use. RESULTS: Antibodies against a recombinant N-terminal fragment of the Candida albicans germ tube-specific antigen hyphal wall protein 1 (Hwp1) generated in Escherichia coli were detected by both immunoblotting and ELISA tests in a group of 36 hematological or Intensive Care Unit patients with invasive candidiasis and in a group of 45 control patients at high risk for the mycosis who did not have clinical or microbiological data to document invasive candidiasis. Results were compared with an immunofluorescence test to detect antibodies to C. albicans germ tubes (CAGT). The sensitivity, specificity, positive and negative predictive values of a diagnostic test based on the detection of antibodies against the N-terminal fragment of Hwp1 by immunoblotting were 27.8 %, 95.6 %, 83.3 % and 62.3 %, respectively. Detection of antibodies to the N-terminal fragment of Hwp1 by ELISA increased the sensitivity (88.9 %) and the negative predictive value (90.2 %) but slightly decreased the specificity (82.6 %) and positive predictive values (80 %). The kinetics of antibody response to the N-terminal fragment of Hwp1 by ELISA was very similar to that observed by detecting antibodies to CAGT. CONCLUSION: An ELISA test to detect antibodies against a recombinant N-terminal fragment of the C. albicans germ tube cell wall antigen Hwp1 allows the diagnosis of invasive candidiasis with similar results to those obtained by detecting antibodies to CAGT but without the need of treating the sera to adsorb the antibodies against the cell wall surface of the blastospore. [Abstract/Link to Full Text]

Whatmore AM, Perrett LL, MacMillan AP
Characterisation of the genetic diversity of Brucella by multilocus sequencing.
BMC Microbiol. 2007;734.
BACKGROUND: Brucella species include economically important zoonotic pathogens that can infect a wide range of animals. There are currently six classically recognised species of Brucella although, as yet unnamed, isolates from various marine mammal species have been reported. In order to investigate genetic relationships within the group and identify potential diagnostic markers we have sequenced multiple genetic loci from a large sample of Brucella isolates representing the known diversity of the genus. RESULTS: Nine discrete genomic loci corresponding to 4,396 bp of sequence were examined from 160 Brucella isolates. By assigning each distinct allele at a locus an arbitrary numerical designation the population was found to represent 27 distinct sequence types (STs). Diversity at each locus ranged from 1.03-2.45% while overall genetic diversity equated to 1.5%. Most loci examined represent housekeeping gene loci and, in all but one case, the ratio of non-synonymous to synonymous change was substantially <1. Analysis of linkage equilibrium between loci indicated a strongly clonal overall population structure. Concatenated sequence data were used to construct an unrooted neighbour-joining tree representing the relationships between STs. This shows that four previously characterized classical Brucella species, B. abortus, B. melitensis, B. ovis and B. neotomae correspond to well-separated clusters. With the exception of biovar 5, B. suis isolates cluster together, although they form a more diverse group than other classical species with a number of distinct STs corresponding to the remaining four biovars. B. canis isolates are located on the same branch very closely related to, but distinguishable from, B. suis biovar 3 and 4 isolates. Marine mammal isolates represent a distinct, though rather weakly supported, cluster within which individual STs display one of three clear host preferences. CONCLUSION: The sequence database provides a powerful dataset for addressing ongoing controversies in Brucella taxonomy and a tool for unambiguously placing atypical, phenotypically discordant or newly emerging Brucella isolates. Furthermore, by using the phylogenetic backbone described here, robust and rationally selected markers for use in diagnostic assay development can be identified. [Abstract/Link to Full Text]

Favre-Bonté S, Chamot E, Köhler T, Romand JA, van Delden C
Autoinducer production and quorum-sensing dependent phenotypes of Pseudomonas aeruginosa vary according to isolation site during colonization of intubated patients.
BMC Microbiol. 2007;733.
BACKGROUND: Pseudomonas aeruginosa frequently colonizes and is responsible for severe ventilator-associated pneumonia in intubated patients. A quorum-sensing (QS) circuit, depending on the production of the two QS-signaling molecules (autoinducers, AIs) 3-oxo-C12-HSL and C4-HSL, regulates the production by P. aeruginosa of several virulence factors and is required for biofilm formation. Therefore QS-inhibition has been suggested as a new target for preventive and/or therapeutic strategies. However the precise role of QS during colonization and subsequent infections of intubated patients remains unclear. RESULTS: We wondered whether QS is active during colonization of intubated patients, and whether P. aeruginosa isolates growing inside the biofilm covering the intubation devices and those resident in the lungs of colonized patients differ in their QS-dependent phenotypes. We collected the intubation devices of eight patients colonized by P. aeruginosa. We detected 3-oxo-C12-HSL on eight, and C4-HSL on six of these devices. In three of these patients we also obtained P. aeruginosa isolates from tracheal aspirates at the time of extubation (n = 18), as well as isolates from the intubation devices (n = 25). We genotyped these isolates, quantified their AIs production, and determined three QS-dependent phenotypes (adherence capacity, biofilm and elastase production). The production of 3-oxo-C12-HSL was consistently increased for isolates from the intubation devices, whereas the production of C4-HSL was significantly higher for isolates from tracheal aspirates. Isolates from tracheal aspirates produced significantly higher amounts of elastase but less biofilm, and had a marginally reduced adhesion capacity than isolates from the intubation devices. Levels of 3-oxo-C12-HSL and elastase production correlated statistically for tracheal intubation isolates, whereas levels of 3-oxo-C12-HSL production and adhesion ability, as well as biofilm production, correlated weakly amongst intubation device isolates. CONCLUSION: Our findings demonstrate that autoinducers are produced during the colonization of intubated patients by P. aeruginosa. The microenvironment, in which P. aeruginosa grows, may select for bacteria with different capacities to produce autoinducers and certain QS-dependent phenotypes. QS-inhibition might therefore affect differently isolates growing inside the biofilm covering intubation devices and those resident in the lungs. [Abstract/Link to Full Text]

Fletcher LA, Gaunt LF, Beggs CB, Shepherd SJ, Sleigh PA, Noakes CJ, Kerr KG
Bactericidal action of positive and negative ions in air.
BMC Microbiol. 2007;732.
BACKGROUND: In recent years there has been renewed interest in the use of air ionisers to control of the spread of airborne infection. One characteristic of air ions which has been widely reported is their apparent biocidal action. However, whilst the body of evidence suggests a biocidal effect in the presence of air ions the physical and biological mechanisms involved remain unclear. In particular, it is not clear which of several possible mechanisms of electrical origin (i.e. the action of the ions, the production of ozone, or the action of the electric field) are responsible for cell death. A study was therefore undertaken to clarify this issue and to determine the physical mechanisms associated with microbial cell death. RESULTS: In the study seven bacterial species (Staphylococcus aureus, Mycobacterium parafortuitum, Pseudomonas aeruginosa, Acinetobacter baumanii, Burkholderia cenocepacia, Bacillus subtilis and Serratia marcescens) were exposed to both positive and negative ions in the presence of air. In order to distinguish between effects arising from: (i) the action of the air ions; (ii) the action of the electric field, and (iii) the action of ozone, two interventions were made. The first intervention involved placing a thin mica sheet between the ionisation source and the bacteria, directly over the agar plates. This intervention, while leaving the electric field unaltered, prevented the air ions from reaching the microbial samples. In addition, the mica plate prevented ozone produced from reaching the bacteria. The second intervention involved placing an earthed wire mesh directly above the agar plates. This prevented both the electric field and the air ions from impacting on the bacteria, while allowing any ozone present to reach the agar plate. With the exception of Mycobacterium parafortuitum, the principal cause of cell death amongst the bacteria studied was exposure to ozone, with electroporation playing a secondary role. However in the case of Mycobacterium parafortuitum, electroporation resulting from exposure to the electric field appears to have been the principal cause of cell inactivation. CONCLUSION: The results of the study suggest that the bactericidal action attributed to negative air ions by previous researchers may have been overestimated. [Abstract/Link to Full Text]

Vilei EM, Correia I, Ferronha MH, Bischof DF, Frey J
Beta-D-glucoside utilization by Mycoplasma mycoides subsp. mycoides SC: possible involvement in the control of cytotoxicity towards bovine lung cells.
BMC Microbiol. 2007;731.
BACKGROUND: Contagious bovine pleuropneumonia (CBPP) caused by Mycoplasma mycoides subsp. mycoides small-colony type (SC) is among the most serious threats for livestock producers in Africa. Glycerol metabolism-associated H2O2 production seems to play a crucial role in virulence of this mycoplasma. A wide number of attenuated strains of M. mycoides subsp. mycoides SC are currently used in Africa as live vaccines. Glycerol metabolism is not affected in these vaccine strains and therefore it does not seem to be the determinant of their attenuation. A non-synonymous single nucleotide polymorphism (SNP) in the bgl gene coding for the 6-phospho-beta-glucosidase (Bgl) has been described recently. The SNP differentiates virulent African strains isolated from outbreaks with severe CBPP, which express the Bgl isoform Val204, from strains to be considered less virulent isolated from CBPP outbreaks with low mortality and vaccine strains, which express the Bgl isoform Ala204. RESULTS: Strains of M. mycoides subsp. mycoides SC considered virulent and possessing the Bgl isoform Val204, but not strains with the Bgl isoform Ala204, do trigger elevated levels of damage to embryonic bovine lung (EBL) cells upon incubation with the disaccharides (i.e., beta-D-glucosides) sucrose and lactose. However, strains expressing the Bgl isoform Val204 show a lower hydrolysing activity on the chromogenic substrate p-nitrophenyl-beta-D-glucopyranoside (pNPbG) when compared to strains that possess the Bgl isoform Ala204. Defective activity of Bgl in M. mycoides subsp. mycoides SC does not lead to H2O2 production. Rather, the viability during addition of beta-D-glucosides in medium-free buffers is higher for strains harbouring the Bgl isoform Val204 than for those with the isoform Ala204. CONCLUSION: Our results indicate that the studied SNP in the bgl gene is one possible cause of the difference in bacterial virulence among strains of M. mycoides subsp. mycoides SC. Bgl does not act as a direct virulence factor, but strains possessing the Bgl isoform Val204 with low hydrolysing activity are more prone to survive in environments that contain high levels of beta-D-glucosides, thus contributing in some extent to mycoplasmaemia. [Abstract/Link to Full Text]

Turner KM, Hanage WP, Fraser C, Connor TR, Spratt BG
Assessing the reliability of eBURST using simulated populations with known ancestry.
BMC Microbiol. 2007;730.
BACKGROUND: The program eBURST uses multilocus sequence typing data to divide bacterial populations into groups of closely related strains (clonal complexes), predicts the founding genotype of each group, and displays the patterns of recent evolutionary descent of all other strains in the group from the founder. The reliability of eBURST was evaluated using populations simulated with different levels of recombination in which the ancestry of all strains was known. RESULTS: For strictly clonal simulations, where all allelic change is due to point mutation, the groups of related strains identified by eBURST were very similar to those expected from the true ancestry and most of the true ancestor-descendant relationships (90-98%) were identified by eBURST. Populations simulated with low or moderate levels of recombination showed similarly high performance but the reliability of eBURST declined with increasing recombination to mutation ratio. Populations simulated under a high recombination to mutation ratio were dominated by a single large straggly eBURST group, which resulted from the incorrect linking of unrelated groups of strains into the same eBURST group. The reliability of the ancestor-descendant links in eBURST diagrams was related to the proportion of strains in the largest eBURST group, which provides a useful guide to when eBURST is likely to be unreliable. CONCLUSION: Examination of eBURST groups within populations of a range of bacterial species showed that most were within the range in which eBURST is reliable, and only a small number (e.g. Burkholderia pseudomallei and Enterococcus faecium) appeared to have such high rates of recombination that eBURST is likely to be unreliable. The study also demonstrates how three simple tests in eBURST v3 can be used to detect unreliable eBURST performance and recognise populations in which there appears to be a high rate of recombination relative to mutation. [Abstract/Link to Full Text]

Bastos KP, Bailão AM, Borges CL, Faria FP, Felipe MS, Silva MG, Martins WS, Fiúza RB, Pereira M, Soares CM
The transcriptome analysis of early morphogenesis in Paracoccidioides brasiliensis mycelium reveals novel and induced genes potentially associated to the dimorphic process.
BMC Microbiol. 2007;729.
BACKGROUND: Paracoccidioides brasiliensis is a human pathogen with a broad distribution in Latin America. The fungus is thermally dimorphic with two distinct forms corresponding to completely different lifestyles. Upon elevation of the temperature to that of the mammalian body, the fungus adopts a yeast-like form that is exclusively associated with its pathogenic lifestyle. We describe expressed sequence tags (ESTs) analysis to assess the expression profile of the mycelium to yeast transition. To identify P. brasiliensis differentially expressed sequences during conversion we performed a large-scale comparative analysis between P. brasiliensis ESTs identified in the transition transcriptome and databases. RESULTS: Our analysis was based on 1107 ESTs from a transition cDNA library of P. brasiliensis. A total of 639 consensus sequences were assembled. Genes of primary metabolism, energy, protein synthesis and fate, cellular transport, biogenesis of cellular components were represented in the transition cDNA library. A considerable number of genes (7.51%) had not been previously reported for P. brasiliensis in public databases. Gene expression analysis using in silico EST subtraction revealed that numerous genes were more expressed during the transition phase when compared to the mycelial ESTs 1. Classes of differentially expressed sequences were selected for further analysis including: genes related to the synthesis/remodeling of the cell wall/membrane. Thirty four genes from this family were induced. Ten genes related to signal transduction were increased. Twelve genes encoding putative virulence factors manifested increased expression. The in silico approach was validated by northern blot and semi-quantitative RT-PCR. CONCLUSION: The developmental program of P. brasiliensis is characterized by significant differential positive modulation of the cell wall/membrane related transcripts, and signal transduction proteins, suggesting the related processes important contributors to dimorphism. Also, putative virulence factors are more expressed in the transition process suggesting adaptation to the host of the yeast incoming parasitic phase. Those genes provide ideal candidates for further studies directed at understanding fungal morphogenesis and its regulation. [Abstract/Link to Full Text]

Werner G, Klare I, Witte W
The current MLVA typing scheme for Enterococcus faecium is less discriminatory than MLST and PFGE for epidemic-virulent, hospital-adapted clonal types.
BMC Microbiol. 2007;728.
BACKGROUND: MLVA (multiple-locus variable-number tandem repeat analysis) is a reliable typing technique introduced recently to differentiate also isolates of Enterococcus faecium. We used the established VNTR (variable number of tandem repeats) scheme to test its suitability to differentiate 58 E. faecium isolates representing mainly outbreaks and clusters of infections and colonizations among patients from 31 German hospitals. All isolates were vancomycin-resistant (vanA type). Typing results for MLVA are compared with results of macrorestriction analysis in PFGE (pulsed-field gel electrophoresis) and MLST (multi-locus sequence typing). RESULTS: All 51 but one hospital isolates from 1996-2006 were assigned to the clonal complex (CC) of epidemic-virulent, hospital-adapted lineages (MLST CC-17; MLVA CC-1) and differed from isolates of sporadic infections and colonizations (n = 7; 1991-1995) and other non-hospital origins (n = 27). Typing of all 58 hospital VRE revealed MLVA as the least discriminatory method (Simpson's diversity index 0.847) when compared to MLST (0.911) and PFGE (0.976). The two most common MLVA types MT-1 (n = 16) and MT-159 (n = 14) combined isolates of several MLST types including also major epidemic, hospital-adapted, clonal types (MT-1: ST-17, ST-18, ST-280, ST-282; MT-159: ST-78, ST-192, ST-203). These data clearly indicate that non-related E. faecium could possess an identical MLVA type being especially critical when MLVA is used to elucidate supposed outbreaks with E. faecium within a single or among different hospitals. Stability of a given MLVA profile MT-12 (ST-117) during an outbreak over a period of five years was also shown. CONCLUSION: MLVA is a suitable method to assign isolates of E. faecium into distinct clonal complexes. To investigate outbreaks the current MLVA typing scheme for E. faecium does not discriminate enough and cannot be recommended as a standard superior to PFGE. [Abstract/Link to Full Text]

Lee L, Tin S, Kelley ST
Culture-independent analysis of bacterial diversity in a child-care facility.
BMC Microbiol. 2007;727.
BACKGROUND: Child-care facilities appear to provide daily opportunities for exposure and transmission of bacteria and viruses. However, almost nothing is known about the diversity of microbial contamination in daycare facilities or its public health implications. Recent culture-independent molecular studies of bacterial diversity in indoor environments have revealed an astonishing diversity of microorganisms, including opportunistic pathogens and many uncultured bacteria. In this study, we used culture and culture-independent methods to determine the viability and diversity of bacteria in a child-care center over a six-month period. RESULTS: We sampled surface contamination on toys and furniture using sterile cotton swabs in four daycare classrooms. Bacteria were isolated on nutrient and blood agar plates, and 16S rRNA gene sequences were obtained from unique (one of a kind) colony morphologies for species identification. We also extracted DNA directly from nine representative swab samples taken over the course of the study from both toy and furniture surfaces, and used "universal" 16S rRNA gene bacterial primers to create PCR-based clone libraries. The rRNA gene clones were sequenced, and the sequences were compared with related sequences in GenBank and subjected to phylogenetic analyses to determine their evolutionary relationships. Culturing methods identified viable bacteria on all toys and furniture surfaces sampled in the study. Bacillus spp. were the most commonly cultured bacteria, followed by Staphylococcus spp., and Microbacterium spp. Culture-independent methods based on 16S rRNA gene sequencing, on the other hand, revealed an entirely new dimension of microbial diversity, including an estimated 190 bacterial species from 15 bacterial divisions. Sequence comparisons and phylogenetic analyses determined that the clone libraries were dominated by a diverse set of sequences related to Pseudomonas spp., as well as uncultured bacteria originally identified on human vaginal epithelium. Other sequences were related to uncultured bacteria from wastewater sludge, and many human-associated bacteria including a number of pathogens and opportunistic pathogens. Our results suggest that the child-care facility provided an excellent habitat for slime-producing Pseudomonads, and that diaper changing contributed significantly to the bacterial contamination. CONCLUSION: The combination of culture and culture-independent methods provided powerful means for determining both viability and diversity of bacteria in child-care facilities. Our results provided insight into the source of contamination and suggested ways in which sanitation might be improved. Although our study identified a remarkable array of microbial diversity present in a single daycare, it also revealed just how little we comprehend the true extent of microbial diversity in daycare centers or other indoor environments. [Abstract/Link to Full Text]

Hovey JG, Watson EL, Langford ML, Hildebrandt E, Bathala S, Bolland JR, Spadafora D, Mendz GL, McGee DJ
Genetic microheterogeneity and phenotypic variation of Helicobacter pylori arginase in clinical isolates.
BMC Microbiol. 2007;726.
BACKGROUND: Clinical isolates of the gastric pathogen Helicobacter pylori display a high level of genetic macro- and microheterogeneity, featuring a panmictic, rather than clonal structure. The ability of H. pylori to survive the stomach acid is due, in part, to the arginase-urease enzyme system. Arginase (RocF) hydrolyzes L-arginine to L-ornithine and urea, and urease hydrolyzes urea to carbon dioxide and ammonium, which can neutralize acid. RESULTS: The degree of variation in arginase was explored at the DNA sequence, enzyme activity and protein expression levels. To this end, arginase activity was measured from 73 minimally-passaged clinical isolates and six laboratory-adapted strains of H. pylori. The rocF gene from 21 of the strains was cloned into genetically stable E. coli and the enzyme activities measured. Arginase activity was found to substantially vary (>100-fold) in both different H. pylori strains and in the E. coli model. Western blot analysis revealed a positive correlation between activity and amount of protein expressed in most H. pylori strains. Several H. pylori strains featured altered arginase activity upon in vitro passage. Pairwise alignments of the 21 rocF genes plus strain J99 revealed extensive microheterogeneity in the promoter region and 3' end of the rocF coding region. Amino acid S232, which was I232 in the arginase-negative clinical strain A2, was critical for arginase activity. CONCLUSION: These studies demonstrated that H. pylori arginase exhibits extensive genotypic and phenotypic variation which may be used to understand mechanisms of microheterogeneity in H. pylori. [Abstract/Link to Full Text]

Mittal S, Mallik S, Sharma S, Virdi JS
Characteristics of beta-lactamases and their genes (blaA and blaB) in Yersinia intermedia and Y. frederiksenii.
BMC Microbiol. 2007;725.
BACKGROUND: The presence of beta-lactamases in Y. enterocolitica has been reported to vary with serovars, biovars and geographical origin of the isolates. An understanding of the beta-lactamases in other related species is important for an overall perception of antibiotic resistance in yersiniae. The objective of this work was to study the characteristics of beta-lactamases and their genes in strains of Y. intermedia and Y. frederiksenii, isolated from clinical and non-clinical sources in India. RESULTS: The enzymes, Bla-A (a constitutive class A penicillinase) and Bla-B (an inducible class C cephalosporinase) were found to be present in all the clinical and non-clinical strains of Y. intermedia and Y. frederiksenii by double disc diffusion method. The results showed differential expression of Bla-A as indicated by presence/absence of synergy whereas expression of Bla-B was quite consistent. The presence of these enzymes was also reflected in the high minimum inhibitory concentrations, MIC50 (126-1024 mg/L) and MIC90 (256-1024 mg/L) of beta-lactam antibiotics against these species. Restriction fragment length polymorphism (RFLP) revealed heterogeneity in both blaA and blaB genes of Y. intermedia and Y. frederiksenii. The blaA gene of Y. intermedia shared significant sequence identity (87-96%) with blaA of Y. enterocolitica biovars 1A, 1B and 4. The sequence identity of blaA of Y. frederiksenii with these biovars was 77-79%. The sequence identity of blaB gene of Y. intermedia and Y. frederiksenii was more (85%) with that of Y. enterocolitica biovars 1A, 1B and 2 compared to other species viz., Y. bercovieri, Y. aldovae and Y. ruckeri. Isoelectric focusing data further revealed that both Y. intermedia and Y. frederiksenii produced Bla-A (pI 8.7) and "Bla-B like" (pI 5.5-7.1) enzymes. CONCLUSION: Both Y. intermedia and Y. frederiksenii showed presence of blaA and blaB genes and unequivocal expression of the two beta-lactamases. Limited heterogeneity was detected in blaA and blaB genes as judged by PCR-RFLP. Phylogenetic relationships showed that the two species shared a high degree of identity in their bla genes. This is the first study reporting characteristics of beta-lactamases and their genes in strains of Y. intermedia and Y. frederiksenii isolated from Asian region. [Abstract/Link to Full Text]

O'Connor EB, Cotter PD, O'Connor P, O'Sullivan O, Tagg JR, Ross RP, Hill C
Relatedness between the two-component lantibiotics lacticin 3147 and staphylococcin C55 based on structure, genetics and biological activity.
BMC Microbiol. 2007;724.
BACKGROUND: Two component lantibiotics, such as the plasmid-encoded lacticin 3147 produced by Lactococcus lactis DPC3147 and staphylococcin C55 produced by Staphylococcus aureus C55, represent an emerging subgroup of bacteriocins. These two bacteriocins are particularly closely related, exhibiting 86% (LtnA1 and C55alpha) and 55% (LtnA2 and C55beta) identity in their component peptides. The aim of this study was to investigate, for the first time for any two component bacteriocins, the significance of the relatedness between these two systems. RESULTS: So close is this relatedness that the hybrid peptide pairs LtnA1:C55beta and C55alpha:LtnA2 were found to have activities in the single nanomolar range, comparing well with the native pairings. To determine whether this flexibility extended to the associated post-translational modification/processing machinery, the staphylococcin C55 structural genes were directly substituted for their lacticin 3147 counterparts in the ltn operon on the large conjugative lactococcal plasmid pMRC01. It was established that the lacticin LtnA1 post-translational and processing machinery could produce functionally active C55alpha, but not C55beta. In order to investigate in closer detail the significance of the differences between LtnA1 and C55alpha, three residues in LtnA1 were replaced with the equivalent residues in C55alpha. Surprisingly, one such mutant LtnA1-Leu21Ala was not produced. This may be significant given the positioning of this residue in a putative lipid II binding loop. CONCLUSION: It is apparent, despite sharing striking similarities in terms of structure and activity, that these two complex bacteriocins display some highly dedicated features particular to either system. [Abstract/Link to Full Text]

U'Ren JM, Schupp JM, Pearson T, Hornstra H, Friedman CL, Smith KL, Daugherty RR, Rhoton SD, Leadem B, Georgia S, Cardon M, Huynh LY, DeShazer D, Harvey SP, Robison R, Gal D, Mayo MJ, Wagner D, Currie BJ, Keim P
Tandem repeat regions within the Burkholderia pseudomallei genome and their application for high resolution genotyping.
BMC Microbiol. 2007;723.
BACKGROUND: The facultative, intracellular bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a serious infectious disease of humans and animals. We identified and categorized tandem repeat arrays and their distribution throughout the genome of B. pseudomallei strain K96243 in order to develop a genetic typing method for B. pseudomallei. We then screened 104 of the potentially polymorphic loci across a diverse panel of 31 isolates including B. pseudomallei, B. mallei and B. thailandensis in order to identify loci with varying degrees of polymorphism. A subset of these tandem repeat arrays were subsequently developed into a multiple-locus VNTR analysis to examine 66 B. pseudomallei and 21 B. mallei isolates from around the world, as well as 95 lineages from a serial transfer experiment encompassing ~18,000 generations. RESULTS: B. pseudomallei contains a preponderance of tandem repeat loci throughout its genome, many of which are duplicated elsewhere in the genome. The majority of these loci are composed of repeat motif lengths of 6 to 9 bp with 4 to 10 repeat units and are predominately located in intergenic regions of the genome. Across geographically diverse B. pseudomallei and B.mallei isolates, the 32 VNTR loci displayed between 7 and 28 alleles, with Nei's diversity values ranging from 0.47 and 0.94. Mutation rates for these loci are comparable (>10-5 per locus per generation) to that of the most diverse tandemly repeated regions found in other less diverse bacteria. CONCLUSION: The frequency, location and duplicate nature of tandemly repeated regions within the B. pseudomallei genome indicate that these tandem repeat regions may play a role in generating and maintaining adaptive genomic variation. Multiple-locus VNTR analysis revealed extensive diversity within the global isolate set containing B. pseudomallei and B. mallei, and it detected genotypic differences within clonal lineages of both species that were identical using previous typing methods. Given the health threat to humans and livestock and the potential for B. pseudomallei to be released intentionally, MLVA could prove to be an important tool for fine-scale epidemiological or forensic tracking of this increasingly important environmental pathogen. [Abstract/Link to Full Text]


Recent Articles in Clinical and Diagnostic Laboratory Immunology

Harimaya A, Tarkkanen J, Mattila P, Fujii N, Ylikoski J, Himi T
Difference in cytokine production and cell activation between adenoidal lymphocytes and peripheral blood lymphocytes of children with otitis media.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1130-4.
We evaluated the immunological potential of adenoidal lymphocytes from children with recurrent otitis media. Interleukin-4 release and CD69 expression were lower in adenoidal lymphocytes than in peripheral blood lymphocytes (PBL). Our results suggest that there may be a difference between the immunological potential of adenoidal lymphocytes and that of PBL in children with otitis. [Abstract/Link to Full Text]

Kirkpatrick BD, Bentley MD, Thern AM, Larsson CJ, Ventrone C, Sreenivasan MV, Bourgeois L
Comparison of the antibodies in lymphocyte supernatant and antibody-secreting cell assays for measuring intestinal mucosal immune response to a novel oral typhoid vaccine (M01ZH09).
Clin Diagn Lab Immunol. 2005 Sep;12(9):1127-9.
Antibody-secreting cell (ASC) and antibodies in lymphocyte supernatant (ALS) assays are used to assess intestinal mucosal responses to enteric infections and vaccines. The ALS assay, performed on cell supernatants, may represent a convenient alternative to the more established ASC assay. The two methods, measuring immunoglobulin A to Salmonella enterica serovar Typhi lipopolysaccharide, were compared in volunteers vaccinated with a live-attenuated typhoid vaccine M01ZH09. The specificity of the ALS assay compared to the ASC assay was excellent (100%), as was sensitivity (82%). The ALS assay was less sensitive than the ASC assay at <or=42 spots/10(6) peripheral blood lymphocytes. [Abstract/Link to Full Text]

Prince HE, Lapé-Nixon M, Busch MP, Tobler LH, Foster GA, Stramer SL
Utilization of follow-up specimens from viremic blood donors to assess the value of west nile virus immunoglobulin G avidity as an indicator of recent infection.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1123-6.
The value of West Nile virus immunoglobulin G avidity for distinguishing recent from past infection was investigated using 348 follow-up specimens from 170 viremic blood donors. Low avidity accurately indicated infection within the previous 4 months. However, due to rapid avidity maturation in some individuals, high avidity did not accurately indicate past infection. [Abstract/Link to Full Text]

Rajagopalan G, Singh M, Sen MM, Murali NS, Nath KA, David CS
Endogenous superantigens shape response to exogenous superantigens.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1119-22.
Endogenous superantigen-mediated thymic negative selection resulted in a paucity of mature T cells bearing T-cell receptor (TCR) Vbeta8 in the periphery. Consequently, the magnitude of immune response to exogenous superantigen staphylococcal enterotoxin B, which activates TCR Vbeta8(+) T cells, was significantly reduced and conferred protection from superantigen-induced mortality. [Abstract/Link to Full Text]

Kandathil AJ, Kannangai R, David S, Selvakumar R, Job V, Abraham OC, Sridharan G
Human immunodeficiency virus infection and levels of Dehydroepiandrosterone sulfate in plasma among Indians.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1117-8.
The shift in cytokine profile during human immunodeficiency virus (HIV) disease progression is influenced by dehydroepiandrosterone sulfate (DHEAS) level. Radioimmunoassay was used to measure plasma DHEAS for 30 treatment-naïve HIV-infected and 30 uninfected individuals. There was a significant negative correlation of viral load with DHEAS level (P<0.05). Further studies of the use of DHEAS levels for monitoring HIV patients economically are warranted. [Abstract/Link to Full Text]

Green BJ, Schmechel D, Tovey ER
Detection of aerosolized Alternaria alternata conidia, hyphae, and fragments by using a novel double-immunostaining technique.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1114-6.
A double-immunostaining halogen immunoassay was developed to identify aerosolized conidia, hyphae, and fragments of Alternaria alternata by using an anti-Alternaria polyclonal antiserum, while, simultaneously, allergy to these components was concurrently determined by using human immunoglobulin E antibodies. [Abstract/Link to Full Text]

Sheoran AS, Feng X, Singh I, Chapman-Bonofiglio S, Kitaka S, Hanawalt J, Nunnari J, Mansfield K, Tumwine JK, Tzipori S
Monoclonal antibodies against Enterocytozoon bieneusi of human origin.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1109-13.
Enterocytozoon bieneusi is clinically the most significant among the microsporidia infecting humans, causing chronic diarrhea, wasting, and cholangitis in individuals with human immunodeficiency virus/AIDS. The lack of immune reagents is largely due to the absence of methods for laboratory propagation of E. bieneusi. We recently described a procedure for the concentration and purification of spores from diarrheic stool of infected humans. Purified spores were used to immunize mice for production and screening of monoclonal antibodies (MAbs) against E. bieneusi. The eight immunoglobulin M MAbs generated and fully characterized did not cross-react with other human microsporidia or with other microorganisms normally present in stool. One of the MAbs, 2G4, reacted with E. bieneusi spores in stools from monkeys and humans, without background fluorescence, which makes it an ideal diagnostic reagent. It also recognizes intracellular stages of the parasite and will be suitable for determining tissue distribution of E. bieneusi in infected hosts. At least two immunodominant antigens of E. bieneusi of 33,000 and 35,000 Da exist, which were recognized by rabbit and mouse antisera. The availability of MAbs against E. bieneusi will simplify considerably the diagnosis of this infection in humans and will provide tools for epidemiologic investigations regarding the true prevalence of the infection in various human and mammalian populations and the environmental sources of infection. [Abstract/Link to Full Text]

Dimech W, Panagiotopoulos L, Marler J, Laven N, Leeson S, Dax EM
Evaluation of three immunoassays used for detection of anti-rubella virus immunoglobulin M antibodies.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1104-8.
Three automated assays (Abbott AxSYM, Bayer ADVIA Centaur, and bioMerieux VIDAS) used for the detection of rubella virus-specific immunoglobulin M were evaluated. A total of 57 samples from individuals with evidence of infection with rubella virus were used to estimate sensitivity, and 220 samples from blood donors and individuals attending an antenatal clinic who had no evidence of recent infection were used to estimate specificity. Seroconversion panels comprising an additional 31 samples from four individuals were used to determine clinical sensitivity. Samples containing potentially cross-reacting substances were also tested. The sensitivities of the three assays ranged from 84.2 to 96.5%, and the specificities ranged from 96.8 to 99.9%. The Abbott AxSYM assay detected more reactive samples than the other two assays when a panel of 57 positive samples was tested. Bayer ADVIA Centaur detected more reactive samples in the seroconversion panels than the other two assays. All three assays evaluated reported a reactive result in 1 or more of the 48 samples containing potentially cross-reacting analytes. The assays demonstrated comparable performance in testing of a well-characterized panel of samples. [Abstract/Link to Full Text]

Puertollano MA, Cruz-Chamorro L, Puertollano E, Pérez-Toscano MT, Alvarez de Cienfuegos G, de Pablo MA
Assessment of interleukin-12, gamma interferon, and tumor necrosis factor alpha secretion in sera from mice fed with dietary lipids during different stages of Listeria monocytogenes infection.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1098-103.
Recent experimental observations have determined that long-chain n-3 polyunsaturated fatty acids suppress immune functions and are involved in the reduction of infectious disease resistance. BALB/c mice were fed for 4 weeks with one of four diets containing either olive oil (OO), fish oil (FO), hydrogenated coconut oil, or a low fat level. Interleukin-12p70 (IL-12p70), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) production in the sera of mice fed these diets and challenged with Listeria monocytogenes were determined by enzyme-linked immunosorbent assay. In addition, bacterial counts from spleens of mice were carried out at 24, 72, or 96 h of infection. Here, we quantified an initial diminution of production of both IL-12p70 and IFN-gamma, which appear to play an important role in the reduction of host resistance to L. monocytogenes infection. In addition, an efficient elimination of L. monocytogenes was observed in spleens of mice fed a diet containing OO at 96 h of infection, despite reductions in IL-12p70 and TNF-alpha production, suggesting an improvement of immune resistance. Overall, our results indicate that the initial reduction of both IL-12 and IFN-gamma production before L. monocytogenes infection represents the most relevant event that corroborates the impairment of immune resistance by n-3 polyunsaturated fatty acids during the different stages of infection. However, we speculate that the modulation of other cytokines must be also involved in this response, because the alteration of cytokine production in mice fed an FO diet in a late phase of L. monocytogenes infection was similar to that in mice fed OO, whereas the ability to eliminate this bacterium from the spleen was improved in the latter group. [Abstract/Link to Full Text]

Falsafi T, Valizadeh N, Sepehr S, Najafi M
Application of a stool antigen test to evaluate the incidence of Helicobacter pylori infection in children and adolescents from Tehran, Iran.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1094-7.
Helicobacter pylori infection is acquired mainly in childhood, especially in developing countries, where a low-cost, rapid diagnostic technique which is reliable for all age groups may be useful for the management of H. pylori infection. For this purpose, we used an HpSA test (Equipar) to detect H. pylori infection in children and adolescents from Tehran, Iran. Thirty-five children who were positive or negative for H. pylori infection by endoscopy-based tests were used as positive and negative controls for the HpSA test. Stools were collected from 430 randomly selected children and adolescents (4 to 18 years old) from southwest, near the center, and northwest of Tehran. A questionnaire that included presence of recurrent abdominal pain (RAP), family history of infection and/or peptic ulcer disease (PUD), and income of parents was completed. A good agreement was found between the results of endoscopy-based tests and those of the HpSA test; the sensitivity and specificity of the Equipar-HpSA test were 100% and 83.4%, respectively. Among 430 children and adolescents, 47% were positive by the HpSA test, of whom 82% had RAP. No difference in incidence was observed between the two sexes; the various categories of age showed an increasing incidence, ranging from 24% (ages 4 to 6) to 58% (ages 16 to 18). The rate of infection in children and adolescents from the southwest was significantly higher (70%) than the rate in those from the northwest (32%), and a family history of H. pylori infection or PUD was observed in 59% of the HpSA positive subjects. The HpSA test is a useful test to detect H. pylori infection in children and adolescents from developing countries. [Abstract/Link to Full Text]

Tavares E, Maldonado R, Ojeda ML, Miñano FJ
Circulating inflammatory mediators during start of fever in differential diagnosis of gram-negative and gram-positive infections in leukopenic rats.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1085-93.
Gram-negative and gram-positive infections have been considered the most important causes of morbidity and mortality in patients with leukopenia following chemotherapy. However, discrimination between bacterial infections and harmless fever episodes is difficult. Because classical inflammatory signs of infection are often absent and fever is frequently the only sign of infection, the aim of this study was to assess the significance of serum interleukin-6 (IL-6), IL-10, macrophage inflammatory protein-2 (MIP-2), procalcitonin (PCT), and C-reactive protein (CRP) patterns in identifying bacterial infections during start of fever in normal and cyclophosphamide-treated (leukopenic) rats following an injection of lipopolysaccharide (LPS) or muramyl dipeptide (MDP) as a model for gram-negative and gram-positive bacterial infections. We found that, compared to normal rats, immunosuppressed animals exhibited significantly higher fevers and lesser production of all mediators, except IL-6, after toxin challenge. Moreover, compared to rats that received MDP, both groups of animals that received an equivalent dose of LPS showed significantly higher fevers and greater increase in serum cytokine levels. Furthermore, in contrast to those in immunocompetent rats, serum levels of IL-6 and MIP-2 were not significantly changed in leukopenic animals after MDP injection. Other serum markers such as PCT and CRP failed to discriminate between bacterial stimuli in both groups of animals. These results suggest that the use of the analyzed serum markers at an early stage of fever could give useful information for the clinician for excluding gram-negative from gram-positive infections. [Abstract/Link to Full Text]

Vinderola G, Matar C, Perdigon G
Role of intestinal epithelial cells in immune effects mediated by gram-positive probiotic bacteria: involvement of toll-like receptors.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1075-84.
The mechanisms by which probiotic bacteria exert their effects on the immune system are not completely understood, but the epithelium may be a crucial player in the orchestration of the effects induced. In a previous work, we observed that some orally administered strains of lactic acid bacteria (LAB) increased the number of immunoglobulin A (IgA)-producing cells in the small intestine without a concomitant increase in the CD4(+) T-cell population, indicating that some LAB strains induce clonal expansion only of B cells triggered to produce IgA. The present work aimed to study the cytokines induced by the interaction of probiotic LAB with murine intestinal epithelial cells (IEC) in healthy animals. We focused our investigation mainly on the secretion of interleukin 6 (IL-6) necessary for the clonal expansion of B cells previously observed with probiotic bacteria. The role of Toll-like receptors (TLRs) in such interaction was also addressed. The cytokines released by primary cultures of IEC in animals fed with Lactobacillus casei CRL 431 or Lactobacillus helveticus R389 were determined. Cytokines were also determined in the supernatants of primary cultures of IEC of unfed animals challenged with different concentrations of viable or nonviable lactobacilli and Escherichia coli, previously blocked or not with anti-TLR2 and anti-TLR4. We concluded that the small intestine is the place where a major distinction would occur between probiotic LAB and pathogens. This distinction comprises the type of cytokines released and the magnitude of the response, cutting across the line that separates IL-6 necessary for B-cell differentiation, which was the case with probiotic lactobacilli, from inflammatory levels of IL-6 for pathogens. [Abstract/Link to Full Text]

Philipp MT, Wormser GP, Marques AR, Bittker S, Martin DS, Nowakowski J, Dally LG
A decline in C6 antibody titer occurs in successfully treated patients with culture-confirmed early localized or early disseminated Lyme Borreliosis.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1069-74.
C(6), a Borrelia burgdorferi-derived peptide, is used as the antigen in the C(6)-Lyme disease diagnostic test. We assessed retrospectively whether a fourfold decrease or a decrease to a negative value in anti-C(6) antibody titer is positively correlated with a positive response to treatment in a sample of culture-confirmed patients with either early localized (single erythema migrans [EM]; n=93) or early disseminated (multiple EM; n=27) disease. All of these patients had been treated with antibiotics and were free of disease within 6 to 12 months of follow-up. Results show that a serum specimen taken at this time was either C(6) negative or had a >or=4-fold decrease in C(6) antibody titer with respect to a specimen taken at baseline (or during the early convalescent period if the baseline specimen was C(6) negative) for all of the multiple-EM patients (P<0.0001) and in 89% of the single-EM patients (P<0.0001). These results indicate that a decline in anti-C(6) antibody titer coincides with effective antimicrobial therapy in patients with early localized or early disseminated Lyme borreliosis. [Abstract/Link to Full Text]

Chaturvedi AK, Kavishwar A, Shiva Keshava GB, Shukla PK
Monoclonal immunoglobulin G1 directed against Aspergillus fumigatus cell wall glycoprotein protects against experimental murine aspergillosis.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1063-8.
Most of the biological functions related to pathogenicity and virulence reside in the fungal cell wall, which, being the outermost part of the cell, mediates the host-fungus interplay. For these reasons much effort has focused on the discovery of useful inhibitors of cell wall glucan, chitin, and mannoprotein biosynthesis. In the absence of a wide-spectrum, safe, and potent antifungal agent, a new strategy for antifungal therapy is directed towards the development of monoclonal antibodies (MAbs). In the present study the MAb A9 (immunoglobulin G1 [IgG1]) was identified from hybridomas raised in BALB/c mice immunized with cell wall antigen of Aspergillus fumigatus. The immunoreactive epitopes for this IgG1 MAb appeared to be associated with a peptide moiety, and indirect immunofluorescence microscopy revealed its binding to the cell wall surface of hyphae as well as with swollen conidia. MAb A9 inhibited hyphal development as observed by MTT [3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay (25.76%), reduced the duration of spore germination, and exerted an in vitro cidal effect against Aspergillus fumigatus. The in vivo protective efficacy of MAb A9 was also evaluated in a murine model of invasive aspergillosis, where a reduction in CFU (>4 log(10) units) was observed in kidney tissue of BALB/c mice challenged with A. fumigatus (2 x 10(5) CFU/ml) and where enhanced mean survival times (19.5 days) compared to the control (7.1 days) and an irrelevant MAb (6.1 days) were also observed. [Abstract/Link to Full Text]

Colombet I, Saguez C, Sanson-Le Pors MJ, Coudert B, Chatellier G, Espinoza P
Diagnosis of tetanus immunization status: multicenter assessment of a rapid biological test.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1057-62.
Diagnosis of tetanus immunization status by medical interview of patients with wounds is poor. Many protected patients receive unnecessary vaccine or immunoglobulin, and unprotected patients may receive nothing. The aim of this study is to evaluate the feasibility and accuracy of the Tetanos Quick Stick (TQS) rapid finger prick stick test in the emergency department for determining immunization status. We designed a prospective multicenter study for blinded comparison of TQS with an enzyme-linked immunosorbent assay (ELISA). Adults referred for open wounds in 37 French hospital emergency departments had the TQS after receiving standard care (emergency-TQS). TQS was also performed in the hospital laboratory on total blood (blood/lab-TQS) and serum (serum/lab-TQS). ELISA was performed with the same blood sample at a central laboratory. We assessed concordance between emergency-TQS and blood/lab-TQS by the kappa test and the diagnostic accuracy (likelihood ratios) of medical interview, emergency-TQS, and lab-TQS. ELISA was positive in 94.6% of the 988 patients included. Concordance between blood/emergency-TQS and blood/lab-TQS results was moderate (kappa=0.6), with a high proportion of inconclusive blood/emergency-TQS tests (9.8%). Likelihood ratios for immunization were 3.0 (95% confidence interval [CI], 1.8 to 5.1), 36.6 (95% CI, 5.3 to 255.3), 89.1 (95% CI, 5.6 to 1,405.0), and 92.7 (95% CI, 5.9 to 1,462.0) for medical interview, blood/emergency-TQS, blood/lab-TQS, and serum/lab-TQS, respectively. The sensitivity of the blood/emergency-TQS was 76.7%, and the specificity was 98% by reference to the ELISA. TQS use in the emergency room could make tetanus prevention more accurate if its technical feasibility were improved, and our assessment will be supplemented by a cost effectiveness study. [Abstract/Link to Full Text]

Hoane JS, Morrow JK, Saville WJ, Dubey JP, Granstrom DE, Howe DK
Enzyme-linked immunosorbent assays for detection of equine antibodies specific to Sarcocystis neurona surface antigens.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1050-6.
Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM. [Abstract/Link to Full Text]

Atochina O, Harn D
LNFPIII/LeX-stimulated macrophages activate natural killer cells via CD40-CD40L interaction.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1041-9.
Lacto-N-fucopentaose III (LNFPIII) is a human milk sugar containing the biologically active Lewis X (LeX) trisaccharide. LNFPIII/LeX is also expressed by immunosuppressive helminth parasites, by bacteria, and on a number of tumor/cancer cells. In this report, we first demonstrate that LNFPIII activates macrophages in vitro as indicated by upregulation of Gr-1 expression on F4/80(+) cells. Further, we investigated the effect of LNFPIII-activated macrophages on NK cell activity. We found that LNFPIII-stimulated F4/80(+) cells were able to activate NK cells, inducing upregulation of CD69 expression and gamma interferon (IFN-gamma) production. The experiments show that NK cell activation is macrophage dependent, since NK cells alone did not secrete IFN-gamma in response to LNFPIII. Furthermore, we found that activation of NK cells by glycan-stimulated macrophages required cell-cell contact. As part of the cell-cell contact mechanism, we determined that CD40-CD40L interaction was critical for IFN-gamma secretion by NK cells, as the addition of anti-CD40L antibodies to the coculture blocked IFN-gamma production. We also demonstrated that LNFPIII-stimulated macrophages secrete prostaglandin E(2), interleukin-10 (IL-10), and tumor necrosis factor alpha (TNF-alpha) but a very low level of IL-12. Interestingly, addition of anti-TNF-alpha, anti-IL-10, or anti-IL-12 monoclonal antibodies did not significantly alter NK cell activity. Our data show that these soluble mediators are not critical for LNFPIII-stimulated macrophage activation of NK cells and provide further evidence for the importance of cell-cell contact and CD40-CD40L interactions between macrophages and NK cells. [Abstract/Link to Full Text]

Marques AR, Hornung RL, Dally L, Philipp MT
Detection of immune complexes is not independent of detection of antibodies in Lyme disease patients and does not confirm active infection with Borrelia burgdorferi.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1036-40.
The Borrelia burgdorferi-specific immune complex (IC) test, which uses polyethylene glycol (PEG) precipitation to isolate ICs from serum, has been used as a research test in the laboratory diagnosis of early Lyme disease (LD) and has been proposed as a marker of active infection. We examined whether B. burgdorferi-specific antibodies were present within PEG-precipitated ICs (PEG-ICs) in patients with LD, posttreatment Lyme disease syndrome, and controls, including individuals who received the outer surface protein A (OspA) vaccine. Using a B. burgdorferi whole-cell enzyme-linked immunosorbent assay (ELISA), we obtained positive PEG-IC results not only in patients with a history of LD, but also in individuals vaccinated with OspA vaccine. The frequency of positive PEG-IC ELISAs in OspA vaccinees was significantly higher with ELISA-reactive than with ELISA-negative unprocessed serum samples (P=0.001), demonstrating dependency between the tests. Similar results were found using samples from rhesus macaques infected with B. burgdorferi, uninfected macaques vaccinated with OspA, and controls. Therefore, testing for the presence of antibodies against B. burgdorferi in PEG-IC preparations is not more likely to reflect active infection than testing in unprocessed serum and should not be used in individuals who received the OspA vaccine. [Abstract/Link to Full Text]

Brunner M
Report refuting value of immune complexes to diagnose Lyme disease is invalid.
Clin Vaccine Immunol. 2006 Feb;13(2):304-5; author reply 305-6. [Abstract/Link to Full Text]

Romero-Steiner S, Holder PF, Gomez de Leon P, Spear W, Hennessy TW, Carlone GM
Avidity determinations for Haemophilus influenzae Type b anti-polyribosylribitol phosphate antibodies.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1029-35.
Determination of antibody avidity measurements can be difficult in human serum depending on the population evaluated. We evaluated three approaches for the determination of antibody avidity for immunoglobulin G (IgG). These approaches were (i) elution of bound antibody with increasing concentrations of a chaotropic agent using a single serum dilution, (ii) binding interference of multiple serum dilutions by a single concentration of a chaotrope, and (iii) elution of multiple serum dilutions by a single concentration of a chaotrope. Parameters that affect the determination of avidity measurements and their limitations were evaluated with pre- and post-Haemophilus influenzae type b conjugate vaccination sera (n=89). We determined that elution of low-avidity antibodies present in multiple dilutions of the serum sample by a single concentration of a chaotrope (0.15 M sodium thiocyanate [NaSCN]) was optimal for the determination of avidity measurements throughout a wide range of IgG concentrations (0.94 to 304.6 microg/ml). The percent reduction in concentration as determined by the elution assay with 0.15 M NaSCN correlated highly (r=0.84) with weighted averages obtained by an elution assay with multiple solutions of NaSCN. The correlation (r=0.57) between elution and binding interference, when a single concentration of a chaotrope was used, was lower than the correlation between the two elution methods (r=0.84). We found that the serum dilution, the heterogeneity of the antibody population, and the concentration of the chaotrope were the primary variables affecting avidity determinations. In this study, we present multiple analysis methods depending on the methodology used. We also present the factors that affect the analysis of avidity determinations given the polyclonal nature of human sera. This experimental approach should benefit the evaluation of similar antibodies induced by other bacterial polysaccharide vaccines. [Abstract/Link to Full Text]

Ndung'u T, Gaseitsiwe S, Sepako E, Doualla-Bell F, Peter T, Kim S, Thior I, Novitsky VA, Essex M
Major histocompatibility complex class II (HLA-DRB and -DQB) allele frequencies in Botswana: association with human immunodeficiency virus type 1 infection.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1020-8.
Southern Africa is facing an unprecedented public health crisis due to the high prevalence of human immunodeficiency virus type 1 (HIV-1). Vaccine development and testing efforts, mainly based on elicitation of HIV-specific T cells, are under way. To understand the role of human leukocyte antigen (HLA) class II alleles in HIV pathogenesis and to facilitate HLA-based HIV-1 vaccine design, we analyzed the frequencies of HLA class II alleles within the southern African country of Botswana. Common HLA class II alleles were identified within the Botswana population through the molecular genotyping of DRB and DQB1 loci. The DRB1 allele groups DRB1*01, DRB1*02/15, DRB1*03, DRB1*11, and DRB1*13 were encountered at frequencies above 20%. Within the DQB1 locus, DQB1*06 (47.7%) was the most common allele group, followed by DQB1*03 (39.2%) and DQB1*04 (25.8%). We found that DRB1*01 was more common in HIV-negative than in HIV-positive individuals and that those who expressed DRB1*08 had lower median viral loads. We demonstrate that the frequencies of certain HLA class II alleles in this Botswana population differ substantially from those in North American populations, including African-Americans. Common allele groups within Botswana cover large percentages of other African populations and could be targeted in regional vaccine designs. [Abstract/Link to Full Text]

Bacon MC, von Wyl V, Alden C, Sharp G, Robison E, Hessol N, Gange S, Barranday Y, Holman S, Weber K, Young MA
The Women's Interagency HIV Study: an observational cohort brings clinical sciences to the bench.
Clin Diagn Lab Immunol. 2005 Sep;12(9):1013-9. [Abstract/Link to Full Text]

Weinberg A
Evaluation of three influenza A and B rapid antigen detection kits--update.
Clin Diagn Lab Immunol. 2005 Aug;12(8):1010. [Abstract/Link to Full Text]

Weinberg A, Walker ML
Evaluation of three immunoassay kits for rapid detection of influenza virus A and B.
Clin Diagn Lab Immunol. 2005 Mar;12(3):367-70.
Influenza causes high morbidity and mortality in very young and elderly individuals, which can be controlled with antivirals and/or vaccines. The success of therapeutic measures is predicated on the rapid and precise diagnosis of the infection. We compared three rapid influenza immunoassay (RIIA) kits for the diagnosis of influenza virus A and B using 178 respiratory specimens submitted for routine testing. BD Directigen Flu A+B (Directigen), Directigen EZ Flu A+B (EZ), and NOW Flu A NOW Flu B (NOW; Binax) tests had comparable combined influenza virus A and B specificities, varying from 94 to 98%. In contrast, the sensitivity of EZ was significantly lower (39%) than that of NOW (76%) and marginally lower than that of Directigen (56%). The differences in sensitivity were most evident in patients who were >9 years old (Directigen, 53%; EZ, 32%; and NOW, 69%). Among specimens, bronchoalveolar lavage fluids yielded the most discrepant results, with sensitivities varying from 0 (EZ) to 100% (NOW), followed by nasopharyngeal swabs (sensitivities of 27 to 100%) and nasal washes (50 to 81%). The Directigen kit format allowed for faster completion but more cumbersome performance and more difficult interpretation compared with the other two kits. Overall, NOW provided the most accurate diagnoses and had user-friendly technical characteristics. However, the low overall sensitivity of the RIIAs indicates that these can be used as screening tools only. [Abstract/Link to Full Text]

Kandathil AJ, Kannangai R, David S, Nithyanandam G, Solomon S, Balakrishnan P, Abraham OC, Subramanian S, Rupali P, Verghese VP, Pulimood S, Sridharan G
Comparison of Microcapillary Cytometry Technology and Flow Cytometry for CD4+ and CD8+ T-Cell Estimation.
Clin Diagn Lab Immunol. 2005 Aug;12(8):1006-9.
An alternative technology for the estimation of T cells based on a microcapillary technique (Guava Technologies, Hayward, CA) was compared to FACSCount (Becton Dickinson, San Jose, CA). Samples from 51 human immunodeficiency virus-infected and 21 healthy individuals were tested. The correlation (r) of the two systems for CD4(+) T cells was 0.994, and the coefficient of variation was 6.5%, establishing equable performance between the two technologies. [Abstract/Link to Full Text]

Nakagawa M, Kim KH, Moscicki AB
Patterns of CD8 T-cell epitopes within the human papillomavirus type 16 (HPV 16) E6 protein among young women whose HPV 16 infection has become undetectable.
Clin Diagn Lab Immunol. 2005 Aug;12(8):1003-5.
The patterns of CD8 T-cell epitopes recognized within the E6 protein in women who had cleared their human papillomavirus 16 infection were examined. T-cell lines were established using autologous dendritic cells infected with a recombinant vaccinia virus. Evidence of potential antigenic epitopes was shown in 8 of 23 (34.8%) women. [Abstract/Link to Full Text]

Lopes AI, Quiding-Jarbrink M, Palha A, Ruivo J, Monteiro L, Oleastro M, Santos A, Fernandes A
Cytokine expression in pediatric Helicobacter pylori infection.
Clin Diagn Lab Immunol. 2005 Aug;12(8):994-1002.
Helicobacter pylori infection is one of the most common gastrointestinal infections worldwide and almost invariably causes chronic gastritis in the infected host. A predominant Th1 profile has been demonstrated in H. pylori-infected mucosa from adults, but no previous study has evaluated in situ cytokine expression in children. We therefore examined expression of proinflammatory, anti-inflammatory, and regulatory cytokines by immunohistochemistry in cryopreserved antral biopsy specimens from 10 H. pylori-infected and 10 uninfected children and correlated expression of cytokines with histology scores. Concomitant expression of interleukin-8 (IL-8), gamma interferon (IFN-gamma), IL-4, transforming growth factor beta, and tumor necrosis factor alpha was seen in 8/10 H. pylori-infected cases and in 5/10 noninfected cases; all H. pylori-infected subjects showed staining for at least two of the cytokines. The proportion of epithelial cytokine-specific staining did not differ significantly between the groups, either in surface or glandular epithelium. Furthermore, no significant differences were noticed between intraepithelial or lamina propria lymphocyte staining in the groups. There was, however, a tendency of higher numbers of IFN-gamma- and IL-8-positive cells in the H. pylori-infected group. IFN-gamma and IL-8 lamina propria lymphocyte expression correlated significantly with antrum chronic inflammation, but there was no correlation between histology scores and epithelial cytokine expression. When the same techniques were used, the cytokine response appeared to be smaller in H. pylori-infected children than in adults, and there was no clear Th1 dominance. These results therefore suggest a different mucosal immunopathology in children. It remains to be determined whether the gastric immune response is downregulated in children with H. pylori infection and whether this is relevant to the outcome of infection. [Abstract/Link to Full Text]

Fraser DG, Leib SR, Zhang BS, Mealey RH, Brown WC, McGuire TC
Lymphocyte proliferation responses induced to broadly reactive Th peptides did not protect against equine infectious anemia virus challenge.
Clin Diagn Lab Immunol. 2005 Aug;12(8):983-93.
The effect of immunization with five lipopeptides, three containing T-helper (Th) epitopes and two with both Th and cytotoxic T-lymphocyte (CTL) epitopes, on equine infectious anemia virus (EIAV) challenge was evaluated. Peripheral blood mononuclear cells from EIAV lipopeptide-immunized horses had significant proliferative responses to Th peptides compared with those preimmunization, and the responses were attributed to significant responses to peptides Gag from positions 221 to 245 (Gag 221-245), Gag 250-269, and Pol 326-347; however, there were no consistent CTL responses. The significant proliferative responses in the EIAV lipopeptide-immunized horses allowed testing of the hypothesis that Th responses to immunization would enhance Th and CTL responses following EIAV challenge and lessen the viral load and the severity of clinical disease. The EIAV lipopeptide-immunized group did have a significant increase in proliferative responses to Th peptides 1 week after virus challenge, whereas the control group did not. Two weeks after challenge, a significant CTL response to virus-infected cell targets occurred in the EIAV lipopeptide-immunized group compared to that in the control group. These Th and CTL responses did not significantly alter either the number of viral RNA copies/ml or disease severity. Thus, lipopeptide-induced proliferative responses and enhanced Th and CTL responses early after virus challenge were unable to control challenge virus load and clinical disease. [Abstract/Link to Full Text]

Pfrepper KI, Enders G, Gohl M, Krczal D, Hlobil H, Wassenberg D, Soutschek E
Seroreactivity to and avidity for recombinant antigens in toxoplasmosis.
Clin Diagn Lab Immunol. 2005 Aug;12(8):977-82.
To improve serodiagnostic methods for the diagnosis of acute toxoplasmosis during pregnancy, a new test system has been developed and evaluated based on the use of recombinant antigens. Five recombinant Toxoplasma gondii antigens (ROP1, MAG1, SAG1, GRA7, and GRA8) were cloned in Escherichia coli, purified, and applied directly onto nitrocellulose membranes in a line assay (recomLine Toxoplasma). A panel of 102 sera from 25 pregnant women with supposed recent toxoplasmosis and from two symptomatic children was compared to a panel of 71 sera from individuals with past infection. Both panels were analyzed using a recombinant line assay for immunoglobulin G (IgG), IgM, and IgA antibodies and a reference enzyme-linked immunosorbent assay. Within the IgM-positive samples, antibodies against ROP1 were predominant regardless of the infection state. In IgG analysis a characteristic antibody pattern was found for very recent infections. This pattern changed to a different one during the time course of infection: antibodies against GRA7 and GRA8 were characteristic for very early IgG, whereas antibodies against SAG1 and MAG1 appeared significantly later. These results were further confirmed by determination of the IgG antibody avidity for every single recombinant antigen. In the time course of infection, IgG antibodies against the early recognized antigens matured significantly earlier than those directed against the later antigens did. The IgA patterns did not give reliable information about the infection time points. The data revealed that the recombinant line assay provides valuable information on the actual state of infection, especially during the early infection time points. [Abstract/Link to Full Text]

Borrow R, Aaberge IS, Santos GF, Eudey TL, Oster P, Glennie A, Findlow J, Høiby EA, Rosenqvist E, Balmer P, Martin D
Interlaboratory standardization of the measurement of serum bactericidal activity by using human complement against meningococcal serogroup b, strain 44/76-SL, before and after vaccination with the Norwegian MenBvac outer membrane vesicle vaccine.
Clin Diagn Lab Immunol. 2005 Aug;12(8):970-6.
There is currently no standardized serum bactericidal antibody (SBA) assay for evaluating immune responses to meningococcal outer membrane vesicle or protein vaccines. Four laboratories, Manchester Health Protection Agency (MC HPA), New Zealand Institute of Environmental Science and Research Limited (NZ ESR), Norwegian Institute of Public Health (NIPH), and Chiron Vaccines (Chiron), measured SBA titers in the same panel of human sera (n=76) from laboratory staff (n=21) vaccinated with MenBvac. Blood samples were collected prevaccination, prior to each of the three doses of MenBvac given at 6-week intervals, and 6 weeks following the third dose. Initial results showed a number of discrepancies in results between the four participating laboratories. The greatest effect on titers appeared to be due to differences among laboratories in the maintenance of the meningococcal serogroup B test strain, 44/76-SL. A repeat study was conducted using the same frozen isolate (meningococcal serogroup B test strain 44/76-SL), freshly distributed to all four laboratories. Using SBA titers from the tilt method for all samples, and using MC HPA as the comparator, the results were as follows for NZ ESR, NIPH, and Chiron, respectively, using log(10) titers: correlation coefficients (r) were 0.966, 0.967, and 0.936; intercepts were 0.08, 0.15, and 0.17; and slopes were 0.930, 0.851, and 0.891. In both prevaccination and postvaccination samples from 15 subjects assayed by all four laboratories, similar increases in SBA (fourfold or greater) were observed (for 11, 11, 9, and 9 subjects for MC HPA, NZ ESR, NIPH, and Chiron, respectively), and similar percentages of subjects with SBA titers of>or=4 p revaccination and 6 weeks following each dose were found. The SBA assay has been harmonized between the four different laboratories with good agreement on seroconversion rates, n-fold changes in titers, and percentages of subjects with SBA titers of >or=4. [Abstract/Link to Full Text]

Dias D, Van Doren J, Schlottmann S, Kelly S, Puchalski D, Ruiz W, Boerckel P, Kessler J, Antonello JM, Green T, Brown M, Smith J, Chirmule N, Barr E, Jansen KU, Esser MT
Optimization and validation of a multiplexed luminex assay to quantify antibodies to neutralizing epitopes on human papillomaviruses 6, 11, 16, and 18.
Clin Diagn Lab Immunol. 2005 Aug;12(8):959-69.
A human papillomavirus (HPV) multiplexed competitive Luminex immunoassay first described by Opalka et al. (D. Opalka, C. E. Lachman, S. A. MacMullen, K. U. Jansen, J. F. Smith, N. Chirmule, and M. T. Esser, Clin. Diagn. Lab. Immunol. 10:108--15, 2003) was optimized and validated for use in epidemiology studies and vaccine clinical trials. Optimization increased both the analytical sensitivity and the clinical specificity of the assay to more effectively discriminate the low-titer antibody response of HPV-infected persons from noninfected individuals. The characteristics of the assay that were optimized included monoclonal antibody (MAb) specificity, scaling up the conjugation of virus-like particles (VLPs) to microspheres, VLP concentration, MAb concentration, sample matrix, sample dilution, incubation time, heat inactivation of sample sera, and detergent effects on assay buffer. The assay was automated by use of a TECAN Genesis Workstation, thus improving assay throughput, reproducibility, and operator safety. Following optimization, the assay was validated using several distinct serum panels from individuals determined to be at low and high risk for HPV infection. The validated assay was then used to determine the clinical serostatus cutoff. This high-throughput assay has proven useful for performing epidemiology studies and evaluating the efficacy of prophylactic HPV vaccines. [Abstract/Link to Full Text]

Salazar JC, Pope CD, Moore MW, Pope J, Kiely TG, Radolf JD
Lipoprotein-dependent and -independent immune responses to spirochetal infection.
Clin Diagn Lab Immunol. 2005 Aug;12(8):949-58.
In this study, we used the epidermal suction blister technique, in conjunction with multiparameter flow cytometry, to analyze the cellular and cytokine responses elicited by intradermal injection of human volunteers with synthetic analogs for spirochetal lipoproteins and compared the responses to findings previously reported from patients with erythema migrans (EM). Compared with peripheral blood (PB), lipopeptides derived from the N termini of the Borrelia burgdorferi outer surface protein C and the 17-kDa lipoprotein of Treponema pallidum (OspC-L and 17-L, respectively) elicited infiltrates enriched in monocytes/macrophages and dendritic cells (DCs) but also containing substantial percentages of neutrophils and T cells. Monocytoid (CD11c(+)) and plasmacytoid (CD11c(-)) DCs were selectively recruited to the skin in ratios similar to those in PB, but only the former expressed the activation/maturation surface markers CD80, CD83, and DC-SIGN. Monocytes/macrophages and monocytoid DCs, but not plasmacytoid DCs, displayed significant increases in surface expression of Toll-like receptor 1 (TLR1), TLR2, and TLR4. Staining for CD45RO and CD27 revealed that lipopeptides preferentially recruited antigen-experienced T-cell subsets; despite their lack of antigenicity, these agonists induced marked T-cell activation, as evidenced by surface expression of CD69, CD25, and CD71. Lipopeptides also induced significant increases in interleukin 12 (IL-12), IL-10, gamma interferon, and most notably IL-6 without corresponding increases in serum levels of these cytokines. Although lipopeptides and EM lesional infiltrates shared many similarities, differences were noted in a number of immunologic parameters. These studies have provided in situ evidence for a prominent "lipoprotein effect" during human infection while at the same time helping to pinpoint aspects of the cutaneous response that are uniquely driven by spirochetal pathogens. [Abstract/Link to Full Text]

Germenis AE, Yiannaki EE, Zachou K, Roka V, Barbanis S, Liaskos C, Adam K, Kapsoritakis AN, Potamianos S, Dalekos GN
Prevalence and clinical significance of immunoglobulin A antibodies against tissue transglutaminase in patients with diverse chronic liver diseases.
Clin Diagn Lab Immunol. 2005 Aug;12(8):941-8.
The prevalence of celiac disease (CD) and the prevalence and clinical significance of anti-tissue transglutaminase (tTG) antibodies (tTGAbs) in a large series of patients with chronic liver diseases were assessed. We studied 738 patients (462 with chronic viral hepatitis, 117 with autoimmune liver diseases, 113 with alcoholic or nonalcoholic fatty liver disease, and 46 with other liver disorders) and 1,350 healthy controls (HC). Immunoglobulin A (IgA) tTGAbs were measured by enzyme-linked immunosorbent assay and a microsphere-based flow cytometric assay. Positive sera were investigated for IgA antiendomysial antibodies (EmA). IgA tTGAb-positive subjects were invited to undergo a small-intestinal biopsy and HLA-DQ allele typing. Four of 1,350 HC (0.3%) tested tTGAb(+) EmA(+) and underwent a biopsy (CD confirmation in all). Four of 738 liver disease patients tested tTGAbs(+) EmA(+) (0.54%; not statistically significant). Two were HCV infected (1.24%; not statistically significant), and two had transaminasemia of unknown origin. Forty-three patients tested tTGAbs(+) EmA(-) (5.8%; P<0.001 compared to HC). Inhibition experiments verified the existence of specific IgA anti-tTG reactivity. Twenty-six of 43 patients underwent a biopsy (all negative for CD). Binary logistic regression analysis revealed age (P=0.008), cirrhosis (P=0.004), alkaline phosphatase (P=0.026), and antinuclear antibodies (P=0.012) as independent risk factors for tTGAb reactivity among the patients. It was concluded that CD prevalence is the same in HC and patients with chronic liver diseases. The prevalence of tTGAbs is higher in hepatic patients compared to HC, but their specificity for CD diagnosis in this group of patients is low. tTGAbs in patients appear to be associated with the presence of autoimmunity, cirrhosis, and cholestasis, irrespective of the origin of the liver disease. [Abstract/Link to Full Text]


Recent Articles in Clinical and Molecular Allergy

No recent articles are currently available.

Recent Articles in Clinical Microbiology Reviews

Baughn RE, Musher DM
Secondary syphilitic lesions.
Clin Microbiol Rev. 2005 Jan;18(1):205-16.
An important theme that emerges from all early historical accounts is that in addition to the decreased virulence of Treponema pallidum, the incidence of secondary syphilis has decreased drastically over the past three centuries. Even in the early 20th century, most syphilologists were of the opinion that the disease had undergone changes in its manifestations and that they were dealing with an attenuated form of the spirochete. Such opinions were based primarily on the observations that violent cutaneous reactions and fatalities associated with the secondary stage had become extremely rare. The rate of primary and secondary syphilis in the United States increased in 2002 for the second consecutive year. After a decade-long decline that led to an all-time low in 2000, the recent trend is attributable, to a large extent, by a increase in reported syphilis cases among men, particularly homosexual and bisexual men having sex with men. The present review addresses the clinical and diagnostic criteria for the recognition of secondary syphilis, the clinical course and manifestations of the disease if allowed to proceed past the primary stage of disease in untreated individuals, and the treatment for this stage of the disease. [Abstract/Link to Full Text]

Brecher ME, Hay SN
Bacterial contamination of blood components.
Clin Microbiol Rev. 2005 Jan;18(1):195-204.
Blood for transfusion is a potential source of infection by a variety of known and unknown transmissible agents. Over the last 20 years, astounding reductions in the risk of viral infection via allogeneic blood have been achieved. As a result of this success, bacterial contamination of blood products has emerged as the greatest residual source of transfusion-transmitted disease. This paper summarizes the current status of detection, prevention, and elimination of bacteria in blood products for transfusion. [Abstract/Link to Full Text]

Mukherjee PK, Sheehan DJ, Hitchcock CA, Ghannoum MA
Combination treatment of invasive fungal infections.
Clin Microbiol Rev. 2005 Jan;18(1):163-94.
The persistence of high morbidity and mortality from systemic fungal infections despite the availability of novel antifungals points to the need for effective treatment strategies. Treatment of invasive fungal infections is often hampered by drug toxicity, tolerability, and specificity issues, and added complications often arise due to the lack of diagnostic tests and to treatment complexities. Combination therapy has been suggested as a possible approach to improve treatment outcome. In this article, we undertake a historical review of studies of combination therapy and also focus on recent studies involving newly approved antifungal agents. The limitations surrounding antifungal combinations include nonuniform interpretation criteria, inability to predict the likelihood of clinical success, strain variability, and variations in pharmacodynamic/pharmacokinetic properties of antifungals used in combination. The issue of antagonism between polyenes and azoles is beginning to be addressed, but data regarding other drug combinations are not adequate for us to draw definite conclusions. However, recent data have identified potentially useful combinations. Standardization of assay methods and adoption of common interpretive criteria are essential to avoid discrepancies between different in vitro studies. Larger clinical trials are needed to assess whether combination therapy improves survival and treatment outcome in the most seriously debilitated patients afflicted with life-threatening fungal infections. [Abstract/Link to Full Text]

O'hara CM
Manual and automated instrumentation for identification of Enterobacteriaceae and other aerobic gram-negative bacilli.
Clin Microbiol Rev. 2005 Jan;18(1):147-62.
Identification of gram-negative bacilli, both enteric and nonenteric, by conventional methods is not realistic for clinical microbiology laboratories performing routine cultures in today's world. The use of commercial kits, either manual or automated, to identify these organisms is a common practice. The advent of rapid or "spot" testing has eliminated the need for some commonly isolated organisms to be identified with the systems approach. Commercially available systems provide more in-depth identification to the species level as well as detect new and unusual strains. The answers obtained from these systems may not always be correct and must be interpreted with caution. The patient demographics, laboratory workload and work flow, and technologist's skill levels should dictate the system of choice. Cost considerations introduce another variable into the equation affecting choice. Each system has its own strengths and weaknesses, and each laboratory must decide on the level of sophistication that fulfills its particular needs. [Abstract/Link to Full Text]

Chappuis F, Loutan L, Simarro P, Lejon V, Büscher P
Options for field diagnosis of human african trypanosomiasis.
Clin Microbiol Rev. 2005 Jan;18(1):133-46.
Human African trypanosomiasis (HAT) due to Trypanosoma brucei gambiense or T. b. rhodesiense remains highly prevalent in several rural areas of sub-Saharan Africa and is lethal if left untreated. Therefore, accurate tools are absolutely required for field diagnosis. For T. b. gambiense HAT, highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Screening for T. b. rhodesiense infection still relies on clinical features in the absence of serological tests available for field use. Ongoing research is opening perspectives for a new generation of field diagnostics. Also essential for both forms of HAT is accurate determination of the disease stage because of the high toxicity of melarsoprol, the drug most widely used during the neurological stage of the illness. Recent studies have confirmed the high accuracy of raised immunoglobulin M levels in the cerebrospinal fluid for the staging of T. b. gambiense HAT, and a promising simple assay (LATEX/IgM) is being tested in the field. Apart from the urgent need for better tools for the field diagnosis of this neglected disease, improved access to diagnosis and treatment for the population at risk remains the greatest challenge for the coming years. [Abstract/Link to Full Text]

Graczyk TK, Knight R, Tamang L
Mechanical transmission of human protozoan parasites by insects.
Clin Microbiol Rev. 2005 Jan;18(1):128-32.
The filthy breeding habits, feeding mechanisms, and indiscriminate travel between filth and food make some groups of synanthropic insects such as nonbiting flies and cockroaches efficient vectors of human enteric protozoan parasites. Twenty-one species of filth flies have been listed by regulatory agencies concerned with sanitation and public health as causative agents of gastrointestinal diseases based on synanthropy, endophily, communicative behavior, and strong attraction to filth and human food. Outbreaks and cases of food-borne diarrheal diseases in urban and rural areas are closely related to the seasonal increase in abundance of filth flies, and enforced fly control is closely related to reductions in the occurrence of such diseases. Mechanical transmission of human parasites by nonbiting flies and epidemiological involvement of other synanthropic insects in human food-borne diseases have not received adequate scientific attention. [Abstract/Link to Full Text]

Lindahl G, Stålhammar-Carlemalm M, Areschoug T
Surface proteins of Streptococcus agalactiae and related proteins in other bacterial pathogens.
Clin Microbiol Rev. 2005 Jan;18(1):102-27.
Streptococcus agalactiae (group B Streptococcus) is the major cause of invasive bacterial disease, including meningitis, in the neonatal period. Although prophylactic measures have contributed to a substantial reduction in the number of infections, development of a vaccine remains an important goal. While much work in this field has focused on the S. agalactiae polysaccharide capsule, which is an important virulence factor that elicits protective immunity, surface proteins have received increasing attention as potential virulence factors and vaccine components. Here, we summarize current knowledge about S. agalactiae surface proteins, with emphasis on proteins that have been characterized immunochemically and/or elicit protective immunity in animal models. These surface proteins have been implicated in interactions with human epithelial cells, binding to extracellular matrix components, and/or evasion of host immunity. Of note, several S. agalactiae surface proteins are related to surface proteins identified in other bacterial pathogens, emphasizing the general interest of the S. agalactiae proteins. Because some S. agalactiae surface proteins elicit protective immunity, they hold promise as components in a vaccine based only on proteins or as carriers in polysaccharide conjugate vaccines. [Abstract/Link to Full Text]

Takayama K, Wang C, Besra GS
Pathway to synthesis and processing of mycolic acids in Mycobacterium tuberculosis.
Clin Microbiol Rev. 2005 Jan;18(1):81-101.
Mycobacterium tuberculosis is known to synthesize alpha-, methoxy-, and keto-mycolic acids. We propose a detailed pathway to the biosynthesis of all mycolic acids in M. tuberculosis. Fatty acid synthetase I provides C(20)-S-coenzyme A to the fatty acid synthetase II system (FAS-IIA). Modules of FAS-IIA and FAS-IIB introduce cis unsaturation at two locations on a growing meroacid chain to yield three different forms of cis,cis-diunsaturated fatty acids (intermediates to alpha-, methoxy-, and keto-meroacids). These are methylated, and the mature meroacids and carboxylated C(26)-S-acyl carrier protein enter into the final Claisen-type condensation with polyketide synthase-13 (Pks13) to yield mycolyl-S-Pks13. We list candidate genes in the genome encoding the proposed dehydrase and isomerase in the FAS-IIA and FAS-IIB modules. We propose that the processing of mycolic acids begins by transfer of mycolic acids from mycolyl-S-Pks13 to d-mannopyranosyl-1-phosphoheptaprenol to yield 6-O-mycolyl-beta-d-mannopyranosyl-1-phosphoheptaprenol and then to trehalose 6-phosphate to yield phosphorylated trehalose monomycolate (TMM-P). Phosphatase releases the phosphate group to yield TMM, which is immediately transported outside the cell by the ABC transporter. Antigen 85 then catalyzes the transfer of a mycolyl group from TMM to the cell wall arabinogalactan and to other TMMs to produce arabinogalactan-mycolate and trehalose dimycolate, respectively. We list candidate genes in the genome that encode the proposed mycolyltransferases I and II, phosphatase, and ABC transporter. The enzymes within this total pathway are targets for new drug discovery. [Abstract/Link to Full Text]

Hambleton S, Gershon AA
Preventing varicella-zoster disease.
Clin Microbiol Rev. 2005 Jan;18(1):70-80.
Varicella-zoster virus (VZV), the cause of chickenpox and shingles, is a pathogen in retreat following the introduction of mass vaccination in the United States in 1995. The live attenuated Oka vaccine, which is safe and immunogenic, gives good protection against both varicella and zoster in the short to medium term. It has undoubtedly been highly effective to date in reducing all forms of varicella, especially severe disease. However, the huge pool of latent wild-type virus in the population represents a continuing threat. Both the biology and the epidemiology of VZV disease suggest that new vaccination strategies will be required over time. [Abstract/Link to Full Text]

Singh N, Paterson DL
Aspergillus infections in transplant recipients.
Clin Microbiol Rev. 2005 Jan;18(1):44-69.
Aspergillus infections are occurring with an increasing frequency in transplant recipients. Notable changes in the epidemiologic characteristics of this infection have occurred; these include a change in risk factors and later onset of infection. Management of invasive aspergillosis continues to be challenging, and the mortality rate, despite the use of newer antifungal agents, remains unacceptably high. Performing molecular studies to discern new targets for antifungal activity, identifying signaling pathways that may be amenable to immunologic interventions, assessing combination regimens of antifungal agents or combining antifungal agents with modulation of the host defense mechanisms, and devising diagnostic assays that can rapidly and reliably diagnose infections represent areas for future investigations that may lead to further improvement in outcomes. [Abstract/Link to Full Text]

Woodfolk JA
Allergy and dermatophytes.
Clin Microbiol Rev. 2005 Jan;18(1):30-43.
Tinea pedis (athlete's foot) and onychomycosis (infection of the toenails) caused by the dermatophyte fungus Trichophyton are highly prevalent in adults. Several Trichophyton allergens have been identified based on elicitation of immunoglobulin E antibody-mediated immediate-hypersensitivity (IH) responses. Evidence of an etiologic role for Trichophyton in asthma in some subjects with IH and chronic dermatophytosis is provided by bronchial reactivity to Trichophyton. Improvement of asthma after systemic antifungal treatment corroborates this link. A unique feature of Trichophyton allergens is the ability of the same antigen to elicit delayed-type hypersensitivity (DTH) in individuals who lack IH reactivity. Delayed responses appear to confer protection, while IH responses do not, based on the association with acute versus chronic skin infection. The amino acid sequence identity of Trichophyton allergens with diverse enzyme families supports a dual role for these proteins in fungal pathogenesis and allergic disease. Characterizing the immunologic properties of Trichophyton allergens and defining immune mechanisms which drive dichotomous responses are pivotal to understanding the dermatophyte-allergy relationship. Recent studies have identified DTH-associated major T-cell epitopes which could facilitate the development of peptide vaccines. Characterization of additional molecular targets by using new techniques may aid not only in the eradication of infection but also in the resolution of allergic symptoms. [Abstract/Link to Full Text]

Schmunis GA, Cruz JR
Safety of the blood supply in Latin America.
Clin Microbiol Rev. 2005 Jan;18(1):12-29.
Appropriate selection of donors, use of sensitive screening tests, and the application of a mandatory quality assurance system are essential to maintain the safety of the blood supply. Laws, decrees, norms, and/or regulations covering most of these aspects of blood transfusion exist in 16 of the 17 countries in Latin America that are the subject of this review. In 17 countries, there is an information system that, although still incomplete (there are no official reports on adverse events and incidents), allows us to establish progress made on the status of the blood supply since 1993. Most advances originated in increased screening coverage for infectious diseases and better quality assurance. However, in 2001 to 2002, tainted blood may have caused infections in 12 of the 17 countries; no country reached the number of donors considered adequate, i.e., 5% of the population, to avoid blood shortages, or decreased significantly the number of blood banks, although larger blood banks are more efficient and take advantage of economies of scale. In those years, paid donors still existed in four countries and replacement donors made up >75% of the blood donors in another eight countries. In addition, countries did not report the number of voluntary donors who were repeat donors, i.e., the healthiest category. In spite of progress made, more improvements are needed. [Abstract/Link to Full Text]

Borkow G, Bentwich Z
Chronic immune activation associated with chronic helminthic and human immunodeficiency virus infections: role of hyporesponsiveness and anergy.
Clin Microbiol Rev. 2004 Oct;17(4):1012-30, table of contents.
Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the "specific" effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed. [Abstract/Link to Full Text]

Solomon AW, Peeling RW, Foster A, Mabey DC
Diagnosis and assessment of trachoma.
Clin Microbiol Rev. 2004 Oct;17(4):982-1011, table of contents.
Trachoma is caused by Chlamydia trachomatis. Clinical grading with the WHO simplified system can be highly repeatable provided graders are adequately trained and standardized. At the community level, rapid assessments are useful for confirming the absence of trachoma but do not determine the magnitude of the problem in communities where trachoma is present. New rapid assessment protocols incorporating techniques for obtaining representative population samples (without census preparation) may give better estimates of the prevalence of clinical trachoma. Clinical findings do not necessarily indicate the presence or absence of C. trachomatis infection, particularly as disease prevalence falls. The prevalence of ocular C. trachomatis infection (at the community level) is important because it is infection that is targeted when antibiotics are distributed in trachoma control campaigns. Methods to estimate infection prevalence are required. While culture is a sensitive test for the presence of viable organisms and nucleic acid amplification tests are sensitive and specific tools for the presence of chlamydial nucleic acids, the commercial assays presently available are all too expensive, too complex, or too unreliable for use in national programs. There is an urgent need for a rapid, reliable test for C. trachomatis to assist in measuring progress towards the elimination of trachoma. [Abstract/Link to Full Text]

Edwards JL, Apicella MA
The molecular mechanisms used by Neisseria gonorrhoeae to initiate infection differ between men and women.
Clin Microbiol Rev. 2004 Oct;17(4):965-81, table of contents.
The molecular mechanisms used by the gonococcus to initiate infection exhibit gender specificity. The clinical presentations of disease are also strikingly different upon comparison of gonococcal urethritis to gonococcal cervicitis. An intimate association occurs between the gonococcus and the urethral epithelium and is mediated by the asialoglycoprotein receptor. Gonococcal interaction with the urethral epithelia cell triggers cytokine release, which promotes neutrophil influx and an inflammatory response. Similarly, gonococcal infection of the upper female genital tract also results in inflammation. Gonococci invade the nonciliated epithelia, and the ciliated cells are subjected to the cytotoxic effects of tumor necrosis factor alpha induced by gonococcal peptidoglycan and lipooligosaccharide. In contrast, gonococcal infection of the lower female genital tract is typically asymptomatic. This is in part the result of the ability of the gonococcus to subvert the alternative pathway of complement present in the lower female genital tract. Gonococcal engagement of complement receptor 3 on the cervical epithelia results in membrane ruffling and does not promote inflammation. A model of gonococcal pathogenesis is presented in the context of the male and female human urogenital tracts. [Abstract/Link to Full Text]

Rock RB, Gekker G, Hu S, Sheng WS, Cheeran M, Lokensgard JR, Peterson PK
Role of microglia in central nervous system infections.
Clin Microbiol Rev. 2004 Oct;17(4):942-64, table of contents.
The nature of microglia fascinated many prominent researchers in the 19th and early 20th centuries, and in a classic treatise in 1932, Pio del Rio-Hortega formulated a number of concepts regarding the function of these resident macrophages of the brain parenchyma that remain relevant to this day. However, a renaissance of interest in microglia occurred toward the end of the 20th century, fueled by the recognition of their role in neuropathogenesis of infectious agents, such as human immunodeficiency virus type 1, and by what appears to be their participation in other neurodegenerative and neuroinflammatory disorders. During the same period, insights into the physiological and pathological properties of microglia were gained from in vivo and in vitro studies of neurotropic viruses, bacteria, fungi, parasites, and prions, which are reviewed in this article. New concepts that have emerged from these studies include the importance of cytokines and chemokines produced by activated microglia in neurodegenerative and neuroprotective processes and the elegant but astonishingly complex interactions between microglia, astrocytes, lymphocytes, and neurons that underlie these processes. It is proposed that an enhanced understanding of microglia will yield improved therapies of central nervous system infections, since such therapies are, by and large, sorely needed. [Abstract/Link to Full Text]

Tzipori S, Sheoran A, Akiyoshi D, Donohue-Rolfe A, Trachtman H
Antibody therapy in the management of shiga toxin-induced hemolytic uremic syndrome.
Clin Microbiol Rev. 2004 Oct;17(4):926-41, table of contents.
Hemolytic uremic syndrome (HUS) is a disease that can lead to acute renal failure and often to other serious sequelae, including death. The majority of cases are attributed to infections with Escherichia coli, serotype O157:H7 strains in particular, which cause bloody diarrhea and liberate one or two toxins known as Shiga toxins 1 and 2. These toxins are thought to directly be responsible for the manifestations of HUS. Currently, supportive nonspecific treatment is the only available option for the management of individuals presenting with HUS. The benefit of antimicrobial therapy remains uncertain because of several reports which claim that such intervention can in fact exacerbate the syndrome. There have been only a few specific therapies directed against neutralizing the activities of these toxins, but none so far has been shown to be effective. This article reviews the literature on the mechanism of action of these toxins and the clinical manifestations and current management and treatment of HUS. The major focus of the article, however, is the development and rationale for using neutralizing human antibodies to combat this toxin-induced disease. Several groups are currently pursuing this approach with either humanized, chimeric, or human antitoxin antibodies produced in transgenic mice. They are at different phases of development, ranging from preclinical evaluation to human clinical trials. The information available from preclinical studies indicates that neutralizing specific antibodies directed against the A subunit of the toxin can be highly protective. Such antibodies, even when administered well after exposure to bacterial infection and onset of diarrhea, can prevent the occurrence of systemic complications. [Abstract/Link to Full Text]

Debiasi RL, Tyler KL
Molecular methods for diagnosis of viral encephalitis.
Clin Microbiol Rev. 2004 Oct;17(4):903-25, table of contents.
Hundreds of viruses cause central nervous system (CNS) disease, including meningoencephalitis and postinfectious encephalomyelitis, in humans. The cerebrospinal fluid (CSF) is abnormal in >90% of cases; however, routine CSF studies only rarely lead to identification of a specific etiologic agent. Diagnosis of viral infections of the CNS has been revolutionized by the advent of new molecular diagnostic technologies to amplify viral nucleic acid from CSF, including PCR, nucleic acid sequence-based amplification, and branched-DNA assay. PCR is ideally suited for identifying fastidious organisms that may be difficult or impossible to culture and has been widely applied for detection of both DNA and RNA viruses in CSF. The technique can be performed rapidly and inexpensively and has become an integral component of diagnostic medical practice in the United States and other developed countries. In addition to its use for identification of etiologic agents of CNS disease in the clinical setting, PCR has also been used to quantitate viral load and monitor duration and adequacy of antiviral drug therapy. PCR has also been applied in the research setting to help discriminate active versus postinfectious immune-mediate disease, identify determinants of drug resistance, and investigate the etiology of neurologic disease of uncertain cause. This review discusses general principles of PCR and reverse transcription-PCR, including qualitative, quantitative, and multiplex techniques, with comment on issues of sensitivity, specificity, and positive and negative predictive values. The application of molecular diagnostic methods for diagnosis of specific infectious entities is reviewed in detail, including viruses for which PCR is of proven efficacy and is widely available, viruses for which PCR is less widely available or for which PCR has unproven sensitivity and specificity, and nonviral entities which can mimic viral CNS disease. [Abstract/Link to Full Text]

Fayer R
Sarcocystis spp. in human infections.
Clin Microbiol Rev. 2004 Oct;17(4):894-902, table of contents.
Sarcocystis species are intracellular protozoan parasites with an intermediate-definitive host life cycle based on a prey-predator relationship. Asexual stages develop in intermediate hosts after they ingest the oocyst stage from definitive-host feces and terminate with the formation of intramuscular cysts (sarcocysts). Sarcocysts in meat eaten by a definitive host initiate sexual stages in the intestine that terminate in oocysts excreted in the feces. Most Sarcocystis species infect specific hosts or closely related host species. For example, humans and some primates are definitive hosts for Sarcocystis hominis and S. suihominis after eating raw meat from cattle and pigs, respectively. The prevalence of intestinal sarcocystosis in humans is low and is only rarely associated with illness, except in volunteers who ingest large numbers of sarcocysts. Cases of infection of humans as intermediate hosts, with intramuscular cysts, number less than 100 and are of unknown origin. The asexual stages, including sarcocysts, can stimulate a strong inflammatory response. Livestock have suffered acute debilitating infections, resulting in abortion and death or chronic infections with failure to grow or thrive. This review provides a summary of Sarcocystis biology, including its morphology, life cycle, host specificity, prevalence, diagnosis, treatment, and prevention strategies, for human and food animal infections. [Abstract/Link to Full Text]

Kampf G, Kramer A
Epidemiologic background of hand hygiene and evaluation of the most important agents for scrubs and rubs.
Clin Microbiol Rev. 2004 Oct;17(4):863-93, table of contents.
The etiology of nosocomial infections, the frequency of contaminated hands with the different nosocomial pathogens, and the role of health care workers' hands during outbreaks suggest that a hand hygiene preparation should at least have activity against bacteria, yeasts, and coated viruses. The importance of efficacy in choosing the right hand hygiene product is reflected in the new Centers for Disease Control and Prevention guideline on hand hygiene (J. M. Boyce and D. Pittet, Morb. Mortal. Wkly. Rep. 51:1-45, 2002). The best antimicrobial efficacy can be achieved with ethanol (60 to 85%), isopropanol (60 to 80%), and n-propanol (60 to 80%). The activity is broad and immediate. Ethanol at high concentrations (e.g., 95%) is the most effective treatment against naked viruses, whereas n-propanol seems to be more effective against the resident bacterial flora. The combination of alcohols may have a synergistic effect. The antimicrobial efficacy of chlorhexidine (2 to 4%) and triclosan (1 to 2%) is both lower and slower. Additionally, both agents have a risk of bacterial resistance, which is higher for chlorhexidine than triclosan. Their activity is often supported by the mechanical removal of pathogens during hand washing. Taking the antimicrobial efficacy and the mechanical removal together, they are still less effective than the alcohols. Plain soap and water has the lowest efficacy of all. In the new Centers for Disease Control and Prevention guideline, promotion of alcohol-based hand rubs containing various emollients instead of irritating soaps and detergents is one strategy to reduce skin damage, dryness, and irritation. Irritant contact dermatitis is highest with preparations containing 4% chlorhexidine gluconate, less frequent with nonantimicrobial soaps and preparations containing lower concentrations of chlorhexidine gluconate, and lowest with well-formulated alcohol-based hand rubs containing emollients and other skin conditioners. Too few published data from comparative trials are available to reliably rank triclosan. Personnel should be reminded that it is neither necessary nor recommended to routinely wash hands after each application of an alcohol-based hand rub. Long-lasting improvement of compliance with hand hygiene protocols can be successful if an effective and accessible alcohol-based hand rub with a proven dermal tolerance and an excellent user acceptability is supplied, accompanied by education of health care workers and promotion of the use of the product. [Abstract/Link to Full Text]

Clarridge JE
Impact of 16S rRNA gene sequence analysis for identification of bacteria on clinical microbiology and infectious diseases.
Clin Microbiol Rev. 2004 Oct;17(4):840-62, table of contents.
The traditional identification of bacteria on the basis of phenotypic characteristics is generally not as accurate as identification based on genotypic methods. Comparison of the bacterial 16S rRNA gene sequence has emerged as a preferred genetic technique. 16S rRNA gene sequence analysis can better identify poorly described, rarely isolated, or phenotypically aberrant strains, can be routinely used for identification of mycobacteria, and can lead to the recognition of novel pathogens and noncultured bacteria. Problems remain in that the sequences in some databases are not accurate, there is no consensus quantitative definition of genus or species based on 16S rRNA gene sequence data, the proliferation of species names based on minimal genetic and phenotypic differences raises communication difficulties, and microheterogeneity in 16S rRNA gene sequence within a species is common. Despite its accuracy, 16S rRNA gene sequence analysis lacks widespread use beyond the large and reference laboratories because of technical and cost considerations. Thus, a future challenge is to translate information from 16S rRNA gene sequencing into convenient biochemical testing schemes, making the accuracy of the genotypic identification available to the smaller and routine clinical microbiology laboratories. [Abstract/Link to Full Text]

Cox RA, Magee DM
Coccidioidomycosis: host response and vaccine development.
Clin Microbiol Rev. 2004 Oct;17(4):804-39, table of contents.
Coccidioidomycosis is caused by the dimorphic fungi in the genus Coccidioides. These fungi live as mycelia in the soil of desert areas of the American Southwest, and when the infectious spores, the arthroconidia, are inhaled, they convert into the parasitic spherule/endospore phase. Most infections are mild, but these organisms are frank pathogens and can cause severe lethal disease in fully immunocompetent individuals. While there is increased risk of disseminated disease in certain racial groups and immunocompromised persons, the fact that there are hosts who contain the initial infection and exhibit long-term immunity to reinfection supports the hypothesis that a vaccine against these pathogens is feasible. Multiple studies have shown that protective immunity against primary disease is associated with T-helper 1 (Th-1)-associated immune responses. The single best vaccine in animal models, formalin-killed spherules (FKS), was tested in a human trial but was not found to be significantly protective. This result has prompted studies to better define immunodominant Coccidioides antigen with the thought that a subunit vaccine would be protective. These efforts have defined multiple candidates, but the single best individual immunogen is the protein termed antigen 2/proline-rich antigen (Ag2/PRA). Studies in multiple laboratories have shown that Ag2/PRA as both protein and genetic vaccines provides significant protection against mice challenged systemically with Coccidioides. Unfortunately, compared to the FKS vaccine, it is significantly less protective as measured by both assays of reduction in fungal CFU and assays of survival. The capacity of Ag2/PRA to induce only partial protection was emphasized when animals were challenged intranasally. Thus, there is a need to define new candidates to create a multivalent vaccine to increase the effectiveness of Ag2/PRA. Efforts of genomic screening using expression library immunization or bioinformatic approaches to identify new candidates have revealed at least two new protective proteins, expression library immunization antigen 1 (ELI-Ag1) and a beta-1,3-glucanosyltransferase (GEL-1). In addition, previously discovered antigens such as Coccidioides-specific antigen (CSA) should be evaluated in assays of protection. While studies have yet to be completed with combinations of the current candidates, the hypothesis is that with increased numbers of candidates in a multivalent vaccine, there will be increased protection. As the genome sequences of the two Coccidioides strains which are under way are completed and annotated, the effort to find new candidates can increase to provide a complete genomic scan for immunodominant proteins. Thus, much progress has been made in the discovery of subunit vaccine candidates against Coccidioides and there are several candidates showing modest levels of protection, but for complete protection against pulmonary challenge we need to continue the search for additional candidates. [Abstract/Link to Full Text]

Schwebke JR, Burgess D
Trichomoniasis.
Clin Microbiol Rev. 2004 Oct;17(4):794-803, table of contents.
Trichomoniasis is perhaps the most common curable sexually transmitted disease worldwide, yet few resources are devoted to its control. It is associated with potentially serious complications such as preterm birth and human immunodeficiency virus acquisition and transmission. The immunology of a related organism, Tritrichomonas foetus, which causes disease in cattle, has been investigated to some extent, but more work is needed for the human strain, Trichomonas vaginalis. In addition, although trichomoniasis is easily treated with oral metronidazole, there is concern that the number of strains resistant to this antibiotic are increasing, and currently no alternative is licensed in the United States. As more is appreciated concerning the important public health implications of this common infection, more work will need to be done in understanding the diagnosis, treatment, and immunology of this organism. [Abstract/Link to Full Text]

Cudmore SL, Delgaty KL, Hayward-McClelland SF, Petrin DP, Garber GE
Treatment of infections caused by metronidazole-resistant Trichomonas vaginalis.
Clin Microbiol Rev. 2004 Oct;17(4):783-93, table of contents.
Infections with the sexually transmitted protozoan Trichomonas vaginalis are usually treated with metronidazole, a 5-nitroimidazole drug derived from the antibiotic azomycin. Metronidazole treatment is generally efficient in eliminating T. vaginalis infection and has a low risk of serious side effects. However, studies have shown that at least 5% of clinical cases of trichomoniasis are caused by parasites resistant to the drug. The lack of approved alternative therapies for T. vaginalis treatment means that higher and sometimes toxic doses of metronidazole are the only option for patients with resistant disease. Clearly, studies of the treatment and prevention of refractory trichomoniasis are essential. This review describes the mechanisms of metronidazole resistance in T. vaginalis and provides a summary of trichomonicidal and vaccine candidate drugs. [Abstract/Link to Full Text]

Rodriguez M, Fishman JA
Prevention of infection due to Pneumocystis spp. in human immunodeficiency virus-negative immunocompromised patients.
Clin Microbiol Rev. 2004 Oct;17(4):770-82, table of contents.
Pneumocystis infection in humans was originally described in 1942. The organism was initially thought to be a protozoan, but more recent data suggest that it is more closely related to the fungi. Patients with cellular immune deficiencies are at risk for the development of symptomatic Pneumocystis infection. Populations at risk also include patients with hematologic and nonhematologic malignancies, hematopoietic stem cell transplant recipients, solid-organ recipients, and patients receiving immunosuppressive therapies for connective tissue disorders and vasculitides. Trimethoprim-sulfamethoxazole is the agent of choice for prophylaxis against Pneumocystis unless a clear contraindication is identified. Other options include pentamidine, dapsone, dapsone-pyrimethamine, and atovaquone. The risk for PCP varies based on individual immune defects, regional differences, and immunosuppressive regimens. Prophylactic strategies must be linked to an ongoing assessment of the patient's risk for disease. [Abstract/Link to Full Text]

Guyatt HL, Snow RW
Impact of malaria during pregnancy on low birth weight in sub-Saharan Africa.
Clin Microbiol Rev. 2004 Oct;17(4):760-9, table of contents.
Malaria during pregnancy can result in low birth weight (LBW), an important risk factor for infant mortality. This article reviews the pathological effects of malaria during pregnancy and the implications for the newborn's development and survival. Empirical data from throughout Africa on associations between placental malaria and birth weight outcome, birth weight outcome and infant mortality, and the rates of LBW in areas with various levels of malaria transmission are evaluated to assess the increased risks of LBW and infant mortality associated with malaria. It is estimated that in areas where malaria is endemic, around 19% of infant LBWs are due to malaria and 6% of infant deaths are due to LBW caused by malaria. These estimates imply that around 100,000 infant deaths each year could be due to LBW caused by malaria during pregnancy in areas of malaria endemicity in Africa. [Abstract/Link to Full Text]

de Repentigny L, Lewandowski D, Jolicoeur P
Immunopathogenesis of oropharyngeal candidiasis in human immunodeficiency virus infection.
Clin Microbiol Rev. 2004 Oct;17(4):729-59, table of contents.
Oropharyngeal and esophageal candidiases remain significant causes of morbidity in human immunodeficiency virus (HIV)-infected patients, despite the dramatic ability of antiretroviral therapy to reconstitute immunity. Notable advances have been achieved in understanding, at the molecular level, the relationships between the progression of HIV infection, the acquisition, maintenance, and clonality of oral candidal populations, and the emergence of antifungal resistance. However, the critical immunological defects which are responsible for the onset and maintenance of mucosal candidiasis in patients with HIV infection have not been elucidated. The devastating impact of HIV infection on mucosal Langerhans' cell and CD4(+) cell populations is most probably central to the pathogenesis of mucosal candidiasis in HIV-infected patients. However, these defects may be partly compensated by preserved host defense mechanisms (calprotectin, keratinocytes, CD8(+) T cells, and phagocytes) which, individually or together, may limit Candida albicans proliferation to the superficial mucosa. The availability of CD4C/HIV transgenic mice expressing HIV-1 in immune cells has provided the opportunity to devise a novel model of mucosal candidiasis that closely mimics the clinical and pathological features of candidal infection in human HIV infection. These transgenic mice allow, for the first time, a precise cause-and-effect analysis of the immunopathogenesis of mucosal candidiasis in HIV infection under controlled conditions in a small laboratory animal. [Abstract/Link to Full Text]

Waites KB, Talkington DF
Mycoplasma pneumoniae and its role as a human pathogen.
Clin Microbiol Rev. 2004 Oct;17(4):697-728, table of contents.
Mycoplasma pneumoniae is a unique bacterium that does not always receive the attention it merits considering the number of illnesses it causes and the degree of morbidity associated with it in both children and adults. Serious infections requiring hospitalization, while rare, occur in both adults and children and may involve multiple organ systems. The severity of disease appears to be related to the degree to which the host immune response reacts to the infection. Extrapulmonary complications involving all of the major organ systems can occur in association with M. pneumoniae infection as a result of direct invasion and/or autoimmune response. The extrapulmonary manifestations are sometimes of greater severity and clinical importance than the primary respiratory infection. Evidence for this organism's contributory role in chronic lung conditions such as asthma is accumulating. Effective management of M. pneumoniae infections can usually be achieved with macrolides, tetracyclines, or fluoroquinolones. As more is learned about the pathogenesis and immune response elicited by M. pneumoniae, improvement in methods for diagnosis and prevention of disease due to this organism may occur. [Abstract/Link to Full Text]

Sharp SE, Elder BL
Competency assessment in the clinical microbiology laboratory.
Clin Microbiol Rev. 2004 Jul;17(3):681-94, table of contents.
The laboratory comprises an invaluable part of the total health care provided to patients. Competency assessment is one method by which we can verify that our employees are competent to perform laboratory testing and report accurate and timely results. To derive the greatest benefit from the inclusion of competency assessment in the laboratory, we must be sure that we are addressing areas where our efforts can be best utilized to optimize patient care. To be competent, an employee must know how to perform a test, must have the ability to perform the test, must be able to perform the test properly without supervision, and know when there is a problem with the test that must be solved. In some cases, competency assessment protocols may demonstrate areas of competence but can fail to disclose incompetence. For example, challenges of low-complexity tasks (such as reading the technical procedure manual) are inferior to challenges that measure understanding and execution of a protocol, and poorly designed competency challenges will probably not detect substandard laboratory performance. Thus, if we are to receive the greatest benefit from our competency assessment programs, which may be time-consuming for the supervisors and the staff as well, we must not only meet the letter of the law but also find a way to make these assessments meaningful, instructive, and able to detect areas of concern. As we address competency assessment in our laboratories, we must understand that when done properly, competency assessment will reward our organizations and assist us in providing the best possible care to our patients. [Abstract/Link to Full Text]

Kaufman D, Fairchild KD
Clinical microbiology of bacterial and fungal sepsis in very-low-birth-weight infants.
Clin Microbiol Rev. 2004 Jul;17(3):638-80, table of contents.
Twenty percent of very-low-birth-weight (<1500 g) preterm infants experience a serious systemic infection, and despite advances in neonatal intensive care and antimicrobials, mortality is as much as threefold higher for these infants who develop sepsis than their counterparts without sepsis during their hospitalization. Outcomes may be improved by preventative strategies, earlier and accurate diagnosis, and adjunct therapies to combat infection and protect the vulnerable preterm infant during an infection. Earlier diagnosis on the basis of factors such as abnormal heart rate characteristics may offer the ability to initiate treatment prior to the onset of clinical symptoms. Molecular and adjunctive diagnostics may also aid in diagnosing invasive infection when clinical symptoms indicate infection but no organisms are isolated in culture. Due to the high morbidity and mortality, preventative and adjunctive therapies are needed. Prophylaxis has been effective in preventing early-onset group B streptococcal sepsis and late-onset Candida sepsis. Future research in prophylaxis using active and passive immunization strategies offers prevention without the risk of resistance to antimicrobials. Identification of the differences in neonatal intensive care units with low and high infection rates and implementation of infection control measures remain paramount in each neonatal intensive care unit caring for preterm infants. [Abstract/Link to Full Text]


Recent Articles in Infection and Immunity

Bielinska AU, Janczak KW, Landers JJ, Makidon P, Sower LE, Peterson JW, Baker JR
Mucosal immunization with a novel nanoemulsion-based recombinant anthrax protective antigen vaccine protects against Bacillus anthracis spore challenge.
Infect Immun. 2007 Aug;75(8):4020-9.
The currently available commercial human anthrax vaccine requires multiple injections for efficacy and has side effects due to its alum adjuvant. These factors limit its utility when immunizing exposed populations in emergent situations. We evaluated a novel mucosal adjuvant that consists of a nontoxic, water-in-oil nanoemulsion (NE). This material does not contain a proinflammatory component but penetrates mucosal surfaces to load antigens into dendritic cells. Mice and guinea pigs were intranasally immunized with recombinant Bacillus anthracis protective antigen (rPA) mixed in NE as an adjuvant. rPA-NE immunization was effective in inducing both serum anti-PA immunoglobulin G (IgG) and bronchial anti-PA IgA and IgG antibodies after either one or two mucosal administrations. Serum anti-PA IgG2a and IgG2b antibodies and PA-specific cytokine induction after immunization indicate a Th1-polarized immune response. rPA-NE immunization also produced high titers of lethal-toxin-neutralizing serum antibodies in both mice and guinea pigs. Guinea pigs nasally immunized with rPA-NE vaccine were protected against an intradermal challenge with approximately 1,000 times the 50% lethal dose ( approximately 1,000x LD(50)) of B. anthracis Ames strain spores (1.38 x 10(3) spores), which killed control animals within 96 h. Nasal immunization also resulted in 70% and 40% survival rates against intranasal challenge with 10x LD(50) and 100x LD(50) (1.2 x 10(6) and 1.2 x 10(7)) Ames strain spores. Our results indicate that NE can effectively adjuvant rPA for intranasal immunization. This potentially could lead to a needle-free anthrax vaccine requiring fewer doses and having fewer side effects than the currently available human vaccine. [Abstract/Link to Full Text]

Empey KM, Hollifield M, Garvy BA
Exogenous heat-killed Escherichia coli improves alveolar macrophage activity and reduces Pneumocystis carinii lung burden in infant mice.
Infect Immun. 2007 Jul;75(7):3382-93.
Pneumocystis carinii is an opportunistic fungal pathogen that causes life-threatening pneumonia in immunocompromised individuals. Infants appear to be particularly susceptible to Pneumocystis pulmonary infections. We have previously demonstrated that there is approximately a 3-week delay in the clearance of Pneumocystis organisms from pup mouse lungs compared to that in adults. We have further shown that there is approximately a 1-week delay in alveolar macrophage activation in pups versus adult mice. Alveolar macrophages are the primary effector cells responsible for the killing and clearance of Pneumocystis, suggesting that pup alveolar macrophages may be involved in the delayed clearance of this organism. Alveolar macrophages cultured in vitro with Pneumocystis alone demonstrate little to no activation, as indicated by a lack of cytokine production. However, when cultured with lipopolysaccharide (LPS) or zymosan, cytokine production was markedly increased, suggesting that pup alveolar macrophages are specifically unresponsive to Pneumocystis organisms rather than being intrinsically unable to become activated. Furthermore, pup mice treated with aerosolized, heat-killed Escherichia coli in vivo were able to clear Pneumocystis more efficiently than were control mice. Together, these data suggest that while pup alveolar macrophages are unresponsive to P. carinii f. sp. muris organisms, they are capable of activation by heat-killed E. coli in vivo, as well as LPS and zymosan in vitro. The lack of response of pup mice to P. carinii f. sp. muris may reflect protective mechanisms specific to the developing pup lung, but ultimately it results in insufficient clearance of Pneumocystis organisms. [Abstract/Link to Full Text]

Tsuji N, Battsetseg B, Boldbaatar D, Miyoshi T, Xuan X, Oliver JH, Fujisaki K
Babesial vector tick defensin against Babesia sp. parasites.
Infect Immun. 2007 Jul;75(7):3633-40.
Antimicrobial peptides are major components of host innate immunity, a well-conserved, evolutionarily ancient defensive mechanism. Infectious disease-bearing vector ticks are thought to possess specific defense molecules against the transmitted pathogens that have been acquired during their evolution. We found in the tick Haemaphysalis longicornis a novel parasiticidal peptide named longicin that may have evolved from a common ancestral peptide resembling spider and scorpion toxins. H. longicornis is the primary vector for Babesia sp. parasites in Japan. Longicin also displayed bactericidal and fungicidal properties that resemble those of defensin homologues from invertebrates and vertebrates. Longicin showed a remarkable ability to inhibit the proliferation of merozoites, an erythrocyte blood stage of equine Babesia equi, by killing the parasites. Longicin was localized at the surface of the Babesia sp. parasites, as demonstrated by confocal microscopic analysis. In an in vivo experiment, longicin induced significant reduction of parasitemia in animals infected with the zoonotic and murine B. microti. Moreover, RNA interference data demonstrated that endogenous longicin is able to directly kill the canine B. gibsoni, thus indicating that it may play a role in regulating the vectorial capacity in the vector tick H. longicornis. Theoretically, longicin may serve as a model for the development of chemotherapeutic compounds against tick-borne disease organisms. [Abstract/Link to Full Text]

Hyland KV, Leon JS, Daniels MD, Giafis N, Woods LM, Bahk TJ, Wang K, Engman DM
Modulation of autoimmunity by treatment of an infectious disease.
Infect Immun. 2007 Jul;75(7):3641-50.
Chagas' heart disease (CHD), caused by the parasite Trypanosoma cruzi, is the most common form of myocarditis in Central America and South America. Some humans and experimental animals develop both humoral and cell-mediated cardiac-specific autoimmunity during infection. Benznidazole, a trypanocidal drug, is effective at reducing parasite load and decreasing the severity of myocarditis in acutely infected patients. We hypothesized that the magnitude of autoimmunity that develops following T. cruzi infection is directly proportional to the amount of damage caused by the parasite. To test this hypothesis, we used benznidazole to reduce the number of parasites in an experimental model of CHD and determined whether this treatment altered the autoimmune response. Infection of A/J mice with the Brazil strain of T. cruzi leads to the development of severe inflammation, fibrosis, necrosis, and parasitosis in the heart accompanied by vigorous cardiac myosin-specific delayed-type hypersensitivity (DTH) and antibody production at 21 days postinfection. Mice succumbed to infection within a month if left untreated. Treatment of infected mice with benznidazole eliminated mortality and decreased disease severity. Treatment also reduced cardiac myosin-specific DTH and antibody production. Reinfection of treated mice with a heart-derived, virulent strain of T. cruzi or immunization with myosin led to the redevelopment of myosin-specific autoimmune responses and inflammation. These results provide a direct link between the levels of T. cruzi and the presence of autoimmunity and suggest that elimination of the parasite may result in the reduction or elimination of autoimmunity in the chronic phase of infection. [Abstract/Link to Full Text]

Frick JS, Fink K, Kahl F, Niemiec MJ, Quitadamo M, Schenk K, Autenrieth IB
Identification of commensal bacterial strains that modulate Yersinia enterocolitica and dextran sodium sulfate-induced inflammatory responses: implications for the development of probiotics.
Infect Immun. 2007 Jul;75(7):3490-7.
An increasing body of evidence suggests that probiotic bacteria are effective in the treatment of enteric infections, although the molecular basis of this activity remains elusive. To identify putative probiotics, we tested commensal bacteria in terms of their toxicity, invasiveness, inhibition of Yersinia-induced inflammation in vitro and in vivo, and modulation of dextran sodium sulfate (DSS)-induced colitis in mice. The commensal bacteria Escherichia coli, Bifidobacterium adolescentis, Bacteroides vulgatus, Bacteroides distasonis, and Streptococcus salivarius were screened for adhesion to, invasion of, and toxicity for host epithelial cells (EC), and the strains were tested for their ability to inhibit Y. enterocolitica-induced NF-kappaB activation. Additionally, B. adolescentis was administered to mice orally infected with Y. enterocolitica and to mice with mucosae impaired by DSS treatment. None of the commensal bacteria tested was toxic for or invaded the EC. B. adolescentis, B. distasonis, B. vulgatus, and S. salivarius inhibited the Y. enterocolitica-induced NF-kappaB activation and interleukin-8 production in EC. In line with these findings, B. adolescentis-fed mice had significantly lower results for mean pathogen burden in the visceral organs, intestinal tumor necrosis factor alpha mRNA expression, and loss of body weight upon oral infection with Y. enterocolitica. In addition, the administration of B. adolescentis decelerated inflammation upon DSS treatment in mice. We suggest that our approach might help to identify new probiotics to be used for the treatment of inflammatory and infectious gastrointestinal disorders. [Abstract/Link to Full Text]

Pouvelle B, Matarazzo V, Jurzynski C, Nemeth J, Ramharter M, Rougon G, Gysin J
Neural cell adhesion molecule, a new cytoadhesion receptor for Plasmodium falciparum-infected erythrocytes capable of aggregation.
Infect Immun. 2007 Jul;75(7):3516-22.
The cytoadhesion of Plasmodium falciparum-infected erythrocytes (IEs) to the endothelial cells lining the microvasculature, clogging the microvessels of various organs, is a key event in the pathogenesis of certain severe forms of malaria, such as cerebral malaria and pulmonary edema. Studies aiming to identify possible correlations between the severity of clinical cases and the presence of particular cytoadhesion phenotypes have been largely unsuccessful. One of the possible reasons for this failure is that some of the key receptors and/or mechanisms involved have yet to be identified. By combining IE selection, cell transfection, and adhesion inhibition assays, we identified a new cytoadhesion receptor, neural cell adhesion molecule (NCAM). NCAM is a member of the immunoglobulin superfamily and has nonpolysialylated and polysialylated isoforms, the latter being rare in adults. The nonpolysialylated form is present on the surfaces of endothelial cells in the microvessels of various organs in which IE sequestration occurs. We found that multiphenotypic IEs interacted with nonpolysialylated NCAM and with another, as yet unidentified receptor. These IEs also displayed cytoadhesion in flow conditions, presenting the unique ability to form adherent macroaggregates composed of hundreds of IEs. These features may act as virulence factors, increasing the capacity of IEs to clog microvessels via receptor synergy and macroaggregate formation, thereby facilitating the pathogenesis of severe forms of malaria. [Abstract/Link to Full Text]

Chen P, Cisar JO, Hess S, Ho JT, Leung KP
Amended description of the genes for synthesis of Actinomyces naeslundii T14V type 1 fimbriae and associated adhesin.
Infect Immun. 2007 Aug;75(8):4181-5.
The type 1 fimbriae of Actinomyces naeslundii T14V mediate adhesion of this gram-positive species to the tooth surface. The present findings show that the locus for type 1 fimbria production in this strain includes three genes, fimQ for a minor fimbrial subunit that appears to be an adhesin, fimP for the major structural subunit, and srtC1 for a type 1 fimbria-specific sortase involved in the assembly of these structures. [Abstract/Link to Full Text]

Hewitson JP, Hamblin PA, Mountford AP
In the absence of CD154, administration of interleukin-12 restores Th1 responses but not protective immunity to Schistosoma mansoni.
Infect Immun. 2007 Jul;75(7):3539-47.
The cytokine interplay during the development of protective immunity to the radiation-attenuated (RA) schistosome vaccine has been extensively characterized over recent years, yet the role of costimulatory molecules in the development of cell-mediated immunity is much less well understood. Here we demonstrate the importance of CD40/CD154 in vaccine-induced immunity, as CD154(-/-) mice exposed to RA schistosomes develop no protection to challenge infection. We showed that vaccinated CD154(-/-) mice have defective Th1-associated immune responses in the skin-draining lymph nodes and the lungs, with reduced or absent levels of interleukin-12p40 (IL-12p40), gamma interferon, and nitric oxide, but elevated levels of lung IL-4 and IL-5. The expression of major histocompatibility complex II (MHC-II) on antigen-presenting cells recovered from the lungs of vaccinated CD154(-/-) mice was also severely compromised. The administration of anti-CD40 monoclonal antibody (MAb) to CD154(-/-) mice did not reconstitute sustained Th1 responses in the lymph nodes or the lungs, nor did the MAb restore anti-parasite immunoglobulin G production or protective immunity. On the other hand, the administration of recombinant IL-12 (rIL-12) to CD154(-/-) mice shortly after vaccination caused elevated and sustained levels of Th1-associated cytokines, rescued MHC-II expression by lung CD11c(+) cells, and restored the appearance of inflammatory effector foci in the lungs. However, the treatment of CD154(-/-) mice with rIL-12 did not restore protection. We conclude that protective immunity to the RA schistosome vaccine is CD154 dependent but is independent of IL-12-orchestrated cellular immune mechanisms in the lungs. [Abstract/Link to Full Text]

Spinosa MR, Progida C, Talà A, Cogli L, Alifano P, Bucci C
The Neisseria meningitidis capsule is important for intracellular survival in human cells.
Infect Immun. 2007 Jul;75(7):3594-603.
While much data exist in the literature about how Neisseria meningitidis adheres to and invades human cells, its behavior inside the host cell is largely unknown. One of the essential meningococcal attributes for pathogenesis is the polysaccharide capsule, which has been shown to be important for bacterial survival in extracellular fluids. To investigate the role of the meningococcal capsule in intracellular survival, we used B1940, a serogroup B strain, and its isogenic derivatives, which lack either the capsule or both the capsule and the lipooligosaccharide outer core, to infect human phagocytic and nonphagocytic cells and monitor invasion and intracellular growth. Our data indicate that the capsule, which negatively affects bacterial adhesion and, consequently, entry, is, in contrast, fundamental for the intracellular survival of this microorganism. The results of in vitro assays suggest that an increased resistance to cationic antimicrobial peptides (CAMPs), important components of the host innate defense system against microbial infections, is a possible mechanism by which the capsule protects the meningococci in the intracellular environment. Indeed, unencapsulated bacteria were more susceptible than encapsulated bacteria to defensins, cathelicidins, protegrins, and polymyxin B, which has long been used as a model compound to define the mechanism of action of CAMPs. We also demonstrate that both the capsular genes (siaD and lipA) and those encoding an efflux pump involved in resistance to CAMPs (mtrCDE) were up-regulated during the intracellular phase of the infectious cycle. [Abstract/Link to Full Text]

Belperron AA, Dailey CM, Booth CJ, Bockenstedt LK
Marginal zone B-cell depletion impairs murine host defense against Borrelia burgdorferi infection.
Infect Immun. 2007 Jul;75(7):3354-60.
Marginal zone B (MZB) cells are a B-cell subset that produces T-cell-independent antibodies to blood-borne antigens. In this study, we examined the effects of MZB cell depletion on the immune response to the Lyme disease spirochete Borrelia burgdorferi, an extracellular pathogen for which T-cell-independent antibody is an important host defense. MZB cell depletion of C3H/HeJ mice using monoclonal antibody to LFA-1 and alpha(4)beta(1) integrins reduced B. burgdorferi-specific immunoglobulin M (IgM) titers, enhanced pathogen burden, and led to more severe arthritis assessed within the first 2 weeks of infection. In addition, MZB cell-depleted mice had reduced levels of B. burgdorferi-specific IgG, which correlated with diminished splenic CD4+ T-cell-activation, proliferation, and cytokine production. Passive transfer of immune mouse serum from infected control mice into infected MZB cell-depleted mice reduced pathogen burden but did not alter the expression of T-cell activation markers on splenic CD4+ T cells. These findings demonstrate that MZB cells not only are a source of pathogen-specific IgM important for limiting spirochete burden and pathology but also play a prominent role in the priming of splenic T-cell responses to a blood-borne pathogen. [Abstract/Link to Full Text]

Bergman NH, Anderson EC, Swenson EE, Janes BK, Fisher N, Niemeyer MM, Miyoshi AD, Hanna PC
Transcriptional profiling of Bacillus anthracis during infection of host macrophages.
Infect Immun. 2007 Jul;75(7):3434-44.
The interaction between Bacillus anthracis and the mammalian phagocyte is one of the central stages in the progression of inhalational anthrax, and it is commonly believed that the host cell plays a key role in facilitating germination and dissemination of inhaled B. anthracis spores. Given this, a detailed definition of the survival strategies used by B. anthracis within the phagocyte is critical for our understanding of anthrax. In this study, we report the first genome-wide analysis of B. anthracis gene expression during infection of host phagocytes. We developed a technique for specific isolation of bacterial RNA from within infected murine macrophages, and we used custom B. anthracis microarrays to characterize the expression patterns occurring within intracellular bacteria throughout infection of the host phagocyte. We found that B. anthracis adapts very quickly to the intracellular environment, and our analyses identified metabolic pathways that appear to be important to the bacterium during intracellular growth, as well as individual genes that show significant induction in vivo. We used quantitative reverse transcription-PCR to verify that the expression trends that we observed by microarray analysis were valid, and we chose one gene (GBAA1941, encoding a putative transcriptional regulator) for further characterization. A deletion strain missing this gene showed no phenotype in vitro but was significantly attenuated in a mouse model of inhalational anthrax, suggesting that the microarray data described here provide not only the first comprehensive view of how B. anthracis survives within the host cell but also a number of promising leads for further research in anthrax. [Abstract/Link to Full Text]

Slepenkin A, Enquist PA, Hägglund U, de la Maza LM, Elofsson M, Peterson EM
Reversal of the antichlamydial activity of putative type III secretion inhibitors by iron.
Infect Immun. 2007 Jul;75(7):3478-89.
INPs, which are chemically synthesized compounds belonging to a class of acylated hydrazones of salicylaldehydes, can inhibit the growth of Chlamydiaceae. Evidence has been presented that in Yersinia and Chlamydia INPs may affect the type III secretion (T3S) system. In the present study 25 INPs were screened for antichlamydial activity at a concentration of 50 muM, and 14 were able to completely inhibit the growth of Chlamydia trachomatis serovar D in McCoy and HeLa 229 cells. The antichlamydial activities of two of these INPs, INPs 0341 and 0400, were further characterized due to their low cytotoxicity. These compounds were found to inhibit C. trachomatis in a dose-dependent manner; were not toxic to elementary bodies; were cidal at a concentration of > or =20 microM; inhibited all Chlamydiaceae tested; and could inhibit the development of C. trachomatis as determined by the yield of progeny when they were added up to 24 h postinfection. INP 0341 was able to affect the expression of several T3S genes. Compared to the expression in control cultures, lcrH-1, copB, and incA, all middle- to late-expressed T3S genes, were not expressed in the INP 0341-treated cultures 24 to 36 h postinfection. Iron, supplied as ferrous sulfate, as ferric chloride, or as holo-transferrin, was able to negate the antichlamydial properties of the INPs. In contrast, apo-transferrin and other divalent metal ions tested were not able to reverse the inhibitory effect of the INPs. In conclusion, the potent antichlamydial activity of INPs is directly or indirectly linked with iron, and this inhibition of Chlamydia has an effect on the T3S system of this intracellular pathogen. [Abstract/Link to Full Text]

Borenshtein D, Nambiar PR, Groff EB, Fox JG, Schauer DB
Development of fatal colitis in FVB mice infected with Citrobacter rodentium.
Infect Immun. 2007 Jul;75(7):3271-81.
Citrobacter rodentium is the causative agent of transmissible murine colonic hyperplasia. The disease is characterized by severe but temporary epithelial hyperplasia with limited inflammation in the descending colon of adult mice on a variety of genetic backgrounds. The natural history of infection with this murine pathogen has been characterized in outbred Swiss Webster (SW) mice but not in the cognate inbred FVB strain. In contrast to subclinical infection in SW mice, 12-week-old FVB mice developed overt disease with significant weight loss and mortality beginning by 9 days postinoculation (dpi). By 21 dpi, more than 75% of infected FVB mice died or had to be euthanized, whereas no mortality developed in SW mice. Mortality in FVB mice was fully prevented by fluid therapy. Fecal shedding of bacteria was similar in both groups through 9 dpi; however, a slight but significant delay in bacterial clearance was observed in FVB mice by 12 to 18 dpi. SW mice developed hyperplasia with minimal inflammation in the descending colon. FVB mice developed epithelial cell hyperproliferation, severe inflammation with erosions and ulcers, and epithelial atypia by 6 dpi in the descending colon. In the majority of surviving FVB mice, colonic lesions, including epithelial atypia, were reversible, although a small percentage (5 to 7%) exhibited chronic colitis through 7 months postinoculation. The existence of susceptible and resistant lines of mice with similar genetic backgrounds will facilitate the identification of host factors responsible for the outcome of infection and may lead to the development of novel strategies for preventing and treating infectious colitis. [Abstract/Link to Full Text]

Yang HH, Madoff LC, Guttormsen HK, Liu YD, Paoletti LC
Recombinant group B streptococcus Beta C protein and a variant with the deletion of its immunoglobulin A-binding site are protective mouse maternal vaccines and effective carriers in conjugate vaccines.
Infect Immun. 2007 Jul;75(7):3455-61.
Immunogenic vaccines against group B Streptococcus (GBS) have been created by coupling the GBS capsular polysaccharides (CPS) to carrier proteins. The GBS beta C protein (BCP) serves as an effective carrier while inducing protective immunity against BCP-expressing strains. BCP also binds human immunoglobulin A (IgA), a characteristic that may be undesirable for use in humans. Here, we examined the immunogenicity and protective efficacy of a recombinant GBS BCP (rBCP), an rBCP modified to eliminate its IgA-binding site (rBCP(DeltaIgA)), and their corresponding GBS serotype III CPS conjugates (III-rBCP and III-rBCP(DeltaIgA)). Deletion of the IgA-binding site or conjugation to CPS did not alter antigenic BCP epitopes. Recombinant proteins and conjugates elicited specific, high-titered IgG in mice. Antisera to rBCP, rBCP(DeltaIgA), III-rBCP, and III-rBCP(DeltaIgA) opsonized GBS strains A909 (Ia/BCP(+)) and H36B (Ib/BCP(+)) for killing by HL-60 cells; antiserum to III-rBCP and III-rBCP(DeltaIgA) also opsonized strain M781 (III/BCP(-)). Vaccination of female mice with either rBCP or rBCP(DeltaIgA) protected approximately 40% of their pups challenged with GBS strain A909. Pups born to III-rBCP- or III-rBCP(DeltaIgA)-vaccinated dams survived at rates of 56% and 66%, respectively. Over 90% of pups born to dams that received the type III CPS conjugates survived challenge with GBS strain M781. In summary, rBCP and rBCP(DeltaIgA) proteins and the conjugates containing them were immunogenic in mice, inducing both CPS- and protein-specific functional IgG. These results suggest that the rBCP(DeltaIgA) could be used as a carrier to augment the immunogenicity of the CPS while expanding coverage to GBS strains bearing BCP. [Abstract/Link to Full Text]

Dogra N, Warburton C, McMaster WR
Leishmania major abrogates gamma interferon-induced gene expression in human macrophages from a global perspective.
Infect Immun. 2007 Jul;75(7):3506-15.
Infection with Leishmania major triggers several pathways in the host cell that are crucial to initial infection as well as those that are used by Leishmania to enhance its replication and virulence. To identify the molecular events of the host cell in response to Leishmania, the global gene expression of the human monocytic cell line THP-1 either infected with Leishmania major in the presence and absence of gamma interferon (IFN-gamma) or in the presence of IFN-gamma alone was analyzed using high-density human oligonucleotide microarrays, followed by statistical analysis. The persistence of the parasite despite an extensive response to IFN-gamma, added 24 h after infection with L. major, suggests that L. major can survive in an IFN-gamma-enriched environment in vitro. Results demonstrate that L. major counteracts the IFN-gamma response in macrophages on a large scale. Expression of genes involved in the innate immune response, cell adhesion, proteasomal degradation, Toll-like receptor expression, a variety of signaling molecules, and matrix metalloproteinases was significantly modulated. [Abstract/Link to Full Text]

Cerca N, Jefferson KK, Maira-Litrán T, Pier DB, Kelly-Quintos C, Goldmann DA, Azeredo J, Pier GB
Molecular basis for preferential protective efficacy of antibodies directed to the poorly acetylated form of staphylococcal poly-N-acetyl-beta-(1-6)-glucosamine.
Infect Immun. 2007 Jul;75(7):3406-13.
Poly-N-acetyl-glucosamine (PNAG) is a staphylococcal surface polysaccharide influencing biofilm formation that is also under investigation for its vaccine potential. Antibodies that bind to PNAG with either low (<15%) or high (>90%) levels of acetate are superior at opsonic and protective activity compared with antibodies that bind to PNAG with only high levels (>70%) of acetate. PNAG is synthesized by four proteins encoded within the intercellular adhesin (ica) locus icaADBC. In Staphylococcus epidermidis, icaB encodes a deacetylase needed for the surface retention of PNAG and optimal biofilm formation. In this study, we confirmed that icaB plays a similar role in Staphylococcus aureus and found that an icaB mutant of S. aureus expressed significantly less surface-associated PNAG, was highly susceptible to antibody-independent opsonic killing that could not be enhanced with antibody raised against deacetylated PNAG (dPNAG), and had reduced survival capacity in a murine model of bacteremia. In contrast, an icaB-overexpressing strain produced primarily surface-associated PNAG, was more susceptible to opsonophagocytosis with antibody to dPNAG, and had increased survival in a murine bacteremia model. The highly acetylated secreted PNAG was more effective at blocking opsonic killing mediated by a human monoclonal antibody (mAb) to native PNAG than it was at blocking killing mediated by a human mAb to dPNAG, which by itself was a more effective opsonin. Retention of dPNAG on the surface of S. aureus is key to increased survival during bacteremia and also provides a molecular mechanism explaining the superior opsonic and protective activity of antibody to dPNAG. [Abstract/Link to Full Text]

Elliott SR, Spurck TP, Dodin JM, Maier AG, Voss TS, Yosaatmadja F, Payne PD, McFadden GI, Cowman AF, Rogerson SJ, Schofield L, Brown GV
Inhibition of dendritic cell maturation by malaria is dose dependent and does not require Plasmodium falciparum erythrocyte membrane protein 1.
Infect Immun. 2007 Jul;75(7):3621-32.
Red blood cells infected with Plasmodium falciparum (iRBCs) have been shown to modulate maturation of human monocyte-derived dendritic cells (DCs), interfering with their ability to activate T cells. Interaction between Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) and CD36 expressed by DCs is the proposed mechanism, but we show here that DC modulation does not require CD36 binding, PfEMP1, or contact between DCs and infected RBCs and depends on the iRBC dose. iRBCs expressing a PfEMP1 variant that binds chondroitin sulfate A (CSA) but not CD36 were phagocytosed, inhibited lipopolysaccharide (LPS)-induced phenotypic maturation and cytokine secretion, and abrogated the ability of DCs to stimulate allogeneic T-cell proliferation. CD36- and CSA-binding iRBCs showed comparable inhibition. P. falciparum lines rendered deficient in PfEMP1 expression by targeted gene knockout or knockdown also inhibited LPS-induced phenotypic maturation, and separation of DCs and iRBCs in transwells showed that inhibition was not contact dependent. Inhibition was observed at an iRBC:DC ratio of 100:1 but not at a ratio of 10:1. High doses of iRBCs were associated with apoptosis of DCs, which was not activation induced. Lower doses of iRBCs stimulated DC maturation sufficient to activate autologous T-cell proliferation. In conclusion, modulation of DC maturation by P. falciparum is dose dependent and does not require interaction between PfEMP1 and CD36. Inhibition and apoptosis of DCs by high-dose iRBCs may or may not be physiological. However, our observation that low-dose iRBCs initiate functional DC maturation warrants reevaluation and further investigation of DC interactions with blood-stage P. falciparum. [Abstract/Link to Full Text]

Erb-Downward JR, Noverr MC
Characterization of prostaglandin E2 production by Candida albicans.
Infect Immun. 2007 Jul;75(7):3498-505.
Candida albicans produces lipid metabolites that are functionally similar to host prostaglandins. These studies, using mass spectrometry, demonstrate that C. albicans produces authentic prostaglandin E(2) (PGE(2)) from arachidonic acid. Maximal PGE(2) production was achieved at 37 degrees C in stationary-phase culture supernatants and in cell-free lysates generated from stationary-phase cells. Interestingly, PGE(2) production is inhibited by both nonspecific cyclooxygenase and lipoxygenase inhibitors but not by inhibitors specific for the cyclooxygenase 2 isoenzyme. The C. albicans genome does not possess a cyclooxygenase homolog; however, several genes that may play a role in prostaglandin production from C. albicans were investigated. It was found that a C. albicans fatty acid desaturase homolog (Ole2) and a multicopper oxidase homolog (Fet3) play roles in prostaglandin production, with ole2/ole2 and fet3/fet3 mutant strains exhibiting reduced PGE(2) levels compared with parent strains. This work demonstrates that the synthesis of PGE(2) in C. albicans proceeds via novel pathways. [Abstract/Link to Full Text]

Jennings CV, Ahouidi AD, Zilversmit M, Bei AK, Rayner J, Sarr O, Ndir O, Wirth DF, Mboup S, Duraisingh MT
Molecular analysis of erythrocyte invasion in Plasmodium falciparum isolates from Senegal.
Infect Immun. 2007 Jul;75(7):3531-8.
The human malaria parasite, Plasmodium falciparum, utilizes multiple ligand-receptor interactions for the invasion of human erythrocytes. Members of the reticulocyte binding protein homolog (PfRh) family have been shown to be critical for directing parasites to alternative erythrocyte receptors that define invasion pathways. Recent studies have identified gene amplification, sequence polymorphism, and variant expression of PfRh paralogs as mechanisms underlying discrimination between pathways for invasion. In this study, we find considerable heterogeneity in the invasion profiles of clonal, uncultured P. falciparum parasite isolates from a low-transmission area in Senegal. Molecular analyses revealed minimal variation in protein expression levels of the PfRh ligands, PfRh1, PfRh2a, and PfRh2b, and an absence of gene amplification in these isolates. However, significant sequence polymorphism was found within repeat regions of PfRh1, PfRh2a, and PfRh2b. Furthermore, we identified a large sequence deletion ( approximately 0.58 kb) in the C-terminal region of the PfRh2b gene at a high prevalence in this population. In contrast to findings of earlier studies, we found no associations between specific sequence variants and distinct invasion pathways. Overall these data highlight the importance of region-specific elaborations in PfRh sequence and expression polymorphisms, which has important implications in our understanding of how the malaria parasite responds to polymorphisms in erythrocyte receptors and/or evades the immune system. [Abstract/Link to Full Text]

Kim JM, Kim JS, Lee JY, Kim YJ, Youn HJ, Kim IY, Chee YJ, Oh YK, Kim N, Jung HC, Song IS
Vacuolating cytotoxin in Helicobacter pylori water-soluble proteins upregulates chemokine expression in human eosinophils via Ca2+ influx, mitochondrial reactive oxygen intermediates, and NF-kappaB activation.
Infect Immun. 2007 Jul;75(7):3373-81.
Helicobacter pylori-infected gastric mucosa is characterized by infiltration of inflammatory cells such as neutrophils and eosinophils. However, little information is available on the relationship between H. pylori virulence factors and chemokine expression in eosinophils. This study investigates the role of vacuolating cytotoxin (VacA) in chemokine expression from human eosinophils. Eosinophils were isolated from the peripheral blood of healthy volunteers using a magnetic cell separation system. VacA(+) H. pylori water-soluble proteins (WSP) induced higher expression of interleukin-8, growth-related oncogene alpha, monocyte chemotactic protein 1, and RANTES (regulated on activation, normal, T-cell expressed and secreted) than Vac(-) WSP in human eosinophils, as assessed by quantitative reverse transcription-PCR and enzyme-linked immunosorbent assay. Purified VacA not only increased chemokine expression but also activated p65/p50 NF-kappaB heterodimers and phosphorylated IkappaB kinase (IKK) alpha/beta signals in human eosinophils. Inhibition of NF-kappaB and IKK significantly decreased the chemokine expression in VacA-stimulated eosinophils. Furthermore, VacA-induced NF-kappaB activation and chemokine release from eosinophils were dependent on Ca(2+) influx and mitochondrial generation of reactive oxygen intermediates (ROI). These results suggest that NF-kappaB and IKK signals via Ca(2+) influx and mitochondrial ROI play a role in the up-regulation of chemokine expression in eosinophils stimulated with H. pylori VacA. [Abstract/Link to Full Text]

Holden N, Totsika M, Dixon L, Catherwood K, Gally DL
Regulation of P-fimbrial phase variation frequencies in Escherichia coli CFT073.
Infect Immun. 2007 Jul;75(7):3325-34.
Adherence of uropathogenic Escherichia coli to host tissue is required for infection and is mediated by fimbriae, such as pyelonephritis-associated pili (Pap). Expression of P fimbriae is regulated by phase variation, and to date, phase transition frequencies have been measured only for pap regulatory region constructs integrated into the E. coli K-12 chromosome. The aim of this work was to measure P phase transition frequencies in clinical isolates for the first time, including frequencies for the sequenced strain E. coli CFT073. P fimbriation and associated phase transition frequencies were measured for two E. coli clinical isolates and compared with levels for homologous pap constructs in E. coli K-12. Fimbriation and off-to-on transition frequencies were always higher in the clinical isolate. It was concluded that the regulatory inputs controlling papI expression are likely to be different in E. coli CFT073 and E. coli K-12 as (i) phase variation could be stimulated in E. coli K-12 by induction of papI and (ii) the level of expression of a papI::gfp(+) fusion was higher in E. coli CFT073 than in E. coli K-12. Furthermore, phase transition frequencies for the two E. coli CFT073 pap clusters were shown to be different depending on the culture conditions, indicating that there is a hierarchy of expression depending on signal inputs. [Abstract/Link to Full Text]

Diakonova M, Helfer E, Seveau S, Swanson JA, Kocks C, Rui L, Carlier MF, Carter-Su C
Adapter protein SH2-Bbeta stimulates actin-based motility of Listeria monocytogenes in a vasodilator-stimulated phosphoprotein (VASP)-dependent fashion.
Infect Immun. 2007 Jul;75(7):3581-93.
SH2-Bbeta (Src homology 2 Bbeta) is an adapter protein that is required for maximal growth hormone-dependent actin reorganization in membrane ruffling and cell motility. Here we show that SH2-Bbeta is also required for maximal actin-based motility of Listeria monocytogenes. SH2-Bbeta localizes to Listeria-induced actin tails and increases the rate of bacterial propulsion in infected cells and in cell extracts. Furthermore, Listeria motility is decreased in mouse embryo fibroblasts from SH2-B(-/-) mice. Both recruitment of SH2-Bbeta to Listeria and SH2-Bbeta stimulation of actin-based propulsion require the vasodilator-stimulated phosphoprotein (VASP), which binds ActA at the surfaces of Listeria cells and enhances bacterial actin-based motility. SH2-Bbeta enhances actin-based movement of ActA-coated beads in a biomimetic actin-based motility assay, provided that VASP is present. In vitro binding assays show that SH2-Bbeta binds ActA but not VASP; however, binding to ActA is greater in the presence of VASP. Because VASP also plays an essential regulatory role in actin-based processes in eukaryotic cells, the present results provide mechanistic insight into the functions of both SH2-Bbeta and VASP in motility and also increase our understanding of the fundamental mechanism by which Listeria spreads. [Abstract/Link to Full Text]

Mann P, Goebel E, Barbarich J, Pilione M, Kennett M, Harvill E
Use of a genetically defined double mutant strain of Bordetella bronchiseptica lacking adenylate cyclase and type III secretion as a live vaccine.
Infect Immun. 2007 Jul;75(7):3665-72.
While most vaccines consisting of killed bacteria induce high serum antibody titers, they do not always confer protection as effective as that induced by infection, particularly against mucosal pathogens. Bordetella bronchiseptica is a gram-negative respiratory pathogen that is endemic in many nonhuman mammalian populations and causes substantial disease in a variety of animals. At least 14 different live attenuated vaccines against this pathogen are available for use in a variety of livestock and companion animals. However, there are few published data on the makeup or efficacy of these vaccines. Here we report the use of a genetically engineered double mutant of B. bronchiseptica, which lacks adenylate cyclase and type III secretion, as a vaccine candidate. This strain is safe at high doses, even for highly immunocompromised animals, and induces immune responses that are protective against highly divergent B. bronchiseptica strains, preventing colonization in the lower respiratory tract and decreasing the bacterial burden in the upper respiratory tract. This novel B. bronchiseptica vaccine candidate induces strong local immunity while eliminating damage caused by the two predominant cytotoxic mechanisms. [Abstract/Link to Full Text]

Brena S, Omaetxebarría MJ, Elguezabal N, Cabezas J, Moragues MD, Pontón J
Fungicidal monoclonal antibody C7 binds to Candida albicans Als3.
Infect Immun. 2007 Jul;75(7):3680-2.
Monoclonal antibody (MAb) C7 reacted with a >200-kDa component from the Candida albicans cell wall identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry as Als3. It also bound the recombinant N terminus of Als3. Binding of MAb C7 to Als3 may explain the biological activities exerted by the MAb on C. albicans. [Abstract/Link to Full Text]

Moon SK, Woo JI, Lee HY, Park R, Shimada J, Pan H, Gellibolian R, Lim DJ
Toll-like receptor 2-dependent NF-kappaB activation is involved in nontypeable Haemophilus influenzae-induced monocyte chemotactic protein 1 up-regulation in the spiral ligament fibrocytes of the inner ear.
Infect Immun. 2007 Jul;75(7):3361-72.
Inner ear dysfunction secondary to chronic otitis media (OM), including high-frequency sensorineural hearing loss or vertigo, is not uncommon. Although chronic middle ear inflammation is believed to cause inner ear dysfunction by entry of OM pathogen components or cytokines from the middle ear into the inner ear, the underlying mechanisms are not well understood. Previously, we demonstrated that the spiral ligament fibrocyte (SLF) cell line up-regulates monocyte chemotactic protein 1 (MCP-1) expression after treatment with nontypeable Haemophilus influenzae (NTHI), one of the most common OM pathogens. We hypothesized that the SLF-derived MCP-1 plays a role in inner ear inflammation secondary to OM that is responsible for hearing loss and dizziness. The purpose of this study was to investigate the signaling pathway involved in NTHI-induced MCP-1 up-regulation in SLFs. Here we show for the first time that NTHI induces MCP-1 up-regulation in the SLFs via Toll-like receptor 2 (TLR2)-dependent activation of NF-kappaB. TLR2(-/-)- and MyD88(-/-)-derived SLFs revealed involvement of TLR2 and MyD88 in NTHI-induced MCP-1 up-regulation. Studies using chemical inhibitors and dominant-negative constructs demonstrated that it is mediated by the IkappaKbeta-dependent IkappaBalpha phosphorylation and NTHI-induced NF-kappaB nuclear translocation. Furthermore, we demonstrated that the binding of NF-kappaB to the enhancer region of MCP-1 is involved in this up-regulation. In addition, we have identified a potential NF-kappaB motif that is responsive and specific to certain NTHI molecules or ligands. Further studies are necessary to reveal specific ligands of NTHI that activate host receptors. These results may provide us with new therapeutic strategies for prevention of inner ear dysfunction secondary to chronic middle ear inflammation. [Abstract/Link to Full Text]

Peterson JW, Comer JE, Baze WB, Noffsinger DM, Wenglikowski A, Walberg KG, Hardcastle J, Pawlik J, Bush K, Taormina J, Moen S, Thomas J, Chatuev BM, Sower L, Chopra AK, Stanberry LR, Sawada R, Scholz WW, Sircar J
Human monoclonal antibody AVP-21D9 to protective antigen reduces dissemination of the Bacillus anthracis Ames strain from the lungs in a rabbit model.
Infect Immun. 2007 Jul;75(7):3414-24.
Dutch-belted and New Zealand White rabbits were passively immunized with AVP-21D9, a human monoclonal antibody to protective antigen (PA), at the time of Bacillus anthracis spore challenge using either nasal instillation or aerosol challenge techniques. AVP-21D9 (10 mg/kg) completely protected both rabbit strains against lethal infection with Bacillus anthracis Ames spores, regardless of the inoculation method. Further, all but one of the passively immunized animals (23/24) were completely resistant to rechallenge with spores by either respiratory challenge method at 5 weeks after primary challenge. Analysis of the sera at 5 weeks after primary challenge showed that residual human anti-PA levels decreased by 85 to 95%, but low titers of rabbit-specific anti-PA titers were also measured. Both sources of anti-PA could have contributed to protection from rechallenge. In a subsequent study, bacteriological and histopathology analyses revealed that B. anthracis disseminated to the bloodstream in some naïve animals as early as 24 h postchallenge and increased in frequency with time. AVP-21D9 significantly reduced the dissemination of the bacteria to the bloodstream and to various organs following infection. Examination of tissue sections from infected control animals, stained with hematoxylin-eosin and the Gram stain, showed edema and/or hemorrhage in the lungs and the presence of bacteria in mediastinal lymph nodes, with necrosis and inflammation. Tissue sections from infected rabbits dosed with AVP-21D9 appeared comparable to corresponding tissues from uninfected animals despite lethal challenge with B. anthracis Ames spores. Concomitant treatment with AVP-21D9 at the time of challenge conferred complete protection in the rabbit inhalation anthrax model. Early treatment increased the efficacy progressively and in a dose-dependent manner. Thus, AVP-21D9 could offer an adjunct or alternative clinical treatment regimen against inhalation anthrax. [Abstract/Link to Full Text]

Mohapatra NP, Soni S, Bell BL, Warren R, Ernst RK, Muszynski A, Carlson RW, Gunn JS
Identification of an orphan response regulator required for the virulence of Francisella spp. and transcription of pathogenicity island genes.
Infect Immun. 2007 Jul;75(7):3305-14.
Francisella tularensis is a category A agent of biowarfare/biodefense. Little is known about the regulation of virulence gene expression in Francisella spp. Comparatively few regulatory factors exist in Francisella, including those belonging to two-component systems (TCS). However, orphan members of typical TCS can be identified. To determine if orphan TCS members affect Francisella gene expression, a gene encoding a product with high similarity to the Salmonella PmrA response regulator (FTT1557c/FNU0663.2) was deleted in Francisella novicida (a model organism for F. tularensis). The F. novicida pmrA mutant was defective in survival/growth within human and murine macrophage cell lines and was 100% defective in virulence in mice at a dose of up to 10(8) CFU. In addition, the mutant strain demonstrated increased susceptibility to antimicrobial peptide killing, but no differences were observed between the lipid A of the mutant and the parental strain, as has been observed with pmrA mutants of other microbes. The F. novicida pmrA mutant was 100% protective as a single-dose vaccine when challenge was with 10(6) CFU of F. novicida but did not protect against type A Schu S4 wild-type challenge. DNA microarray analysis identified 65 genes regulated by PmrA. The majority of these genes were located in the region surrounding pmrA or within the Francisella pathogenicity island (FPI). These FPI genes are also regulated by MglA, but MglA does not regulate pmrA, nor does PmrA regulate MglA. Thus, the orphan response regulator PmrA is an important factor in controlling virulence in F. novicida, and a pmrA mutant strain is an effective vaccine against homologous challenge. [Abstract/Link to Full Text]

Vlaminckx BJ, Schuren FH, Montijn RC, Caspers MP, Beitsma MM, Wannet WJ, Schouls LM, Verhoef J, Jansen WT
Dynamics in prophage content of invasive and noninvasive M1 and M28 Streptococcus pyogenes isolates in The Netherlands from 1959 to 1996.
Infect Immun. 2007 Jul;75(7):3673-9.
Invasive group A streptococcal (GAS) disease re-emerged in The Netherlands in the late 1980s. To seek an explanation for this resurgence, the genetic compositions of 22 M1 and 19 M28 GAS strains isolated in The Netherlands between 1960s and the mid-1990s were analyzed by using a mixed-genome DNA microarray. During this four-decade period, M1 and especially M28 strains acquired prophages on at least eight occasions. All prophages carried a superantigen (speA2, speC, speK) or a streptodornase (sdaD2, sdn), both associated with invasive GAS disease. Invasive and noninvasive GAS strains did not differ in prophage acquisition, suggesting that there was an overall increase in the pathogenicity of M1 and M28 strains over the last four decades rather than emergence of hypervirulent subclones. The increased overall pathogenic potential may have contributed to the reemergence of invasive GAS disease in The Netherlands. [Abstract/Link to Full Text]

Cheng XJ, Hayasaka H, Watanabe K, Tao YL, Liu JY, Tsukamoto H, Horii T, Tanabe K, Tachibana H
Production of high-affinity human monoclonal antibody fab fragments to the 19-kilodalton C-terminal merozoite surface protein 1 of Plasmodium falciparum.
Infect Immun. 2007 Jul;75(7):3614-20.
A combinatorial immunoglobulin gene library was constructed from peripheral blood lymphocytes of eight patients infected with Plasmodium falciparum and was screened for the production of human monoclonal antibody Fab fragments to the C-terminal 19-kDa fragment of P. falciparum merozoite surface protein 1 (MSP-1(19)). Three Fab clones recognized recombinant MSP-1(19) under nonreducing conditions. Indirect immunofluorescence microscopy demonstrated that three Fab clones stained the surfaces of late trophozoites/schizonts and merozoites of the FCR3 and 3D7 strains, suggesting the Fabs' reactivities to a conserved epitope. Sequence analysis of the heavy-chain genes revealed that the closest germ line V segments were VH1-8 and VH7-81, with 91% to 98% homology. The closest germ line D segment was D3-10, and the closest germ line J segment was JH4 or JH5, with 90% to 97% homology. In the light-chain genes, the closest germ line V segment was A27 for the Jkappa2, Jkappa4, and Jkappa5 segments. The dissociation constants of these Fab fragments for recombinant MSP-1(19) ranged from 1.09 x 10(-9) to 2.66 x 10(-9) M. The binding of the three Fab fragments to MSP-1(19) was competitively inhibited by the anti-MSP-1(19) mouse monoclonal antibody 12.8, which inhibits erythrocyte invasion by merozoites. However, the human Fab fragment with the highest affinity did not inhibit in vitro growth of P. falciparum. This is the first report of gene analysis and bacterial expression of human monoclonal antibodies to P. falciparum MSP-1(19). The combinatorial immunoglobulin gene library derived from malaria patients provides a potential tool for producing high-affinity human antibodies specific for P. falciparum. [Abstract/Link to Full Text]

Albert MJ, Haridas S, Steer D, Dhaunsi GS, Smith AI, Adler B
Identification of a Campylobacter jejuni protein that cross-reacts with cholera toxin.
Infect Immun. 2007 Jun;75(6):3070-3.
The question of whether Campylobacter jejuni produces a cholera toxin-like toxin (CTLT) has been controversial. The objective of this study was to identify the factor that cross-reacts with CT from C. jejuni. Filtrates of C. jejuni grown in four different liquid media reported to promote CTLT production were tested by Chinese hamster ovary (CHO) cell elongation assay and for reactivity with CT antibody using GM1 ganglioside enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Protein sequence was determined by matrix-assisted laser desorption ionization-time of flight (MALDI TOF-TOF). Filtrates from seven reference strains reported to produce CTLT and from 80 clinical strains were negative in the CHO cell assay, but those from three reference strains and 16 clinical strains were positive by GM1 ELISA. All strains tested, including C. jejuni NCTC 11168, which does not contain a CT gene homologue, possessed a 53-kDa protein which reacted with CT antibody by immunoblotting. This band was identified as the major outer membrane protein, PorA, of C. jejuni. CT antibody reacted by immunoblotting with a recombinant PorA, but antibody to the recombinant PorA did not react with CT. Our results indicate that C. jejuni does not produce a functional CTLT, but the reactivity of PorA with CT antibody would lead to the erroneous conclusion that C. jejuni produces a functional CTLT. [Abstract/Link to Full Text]


Recent Articles in Journal of Bacteriology

Lu Z, Takeuchi M, Sato T
The LysR-type transcriptional regulator YofA controls cell division through the regulation of expression of ftsW in Bacillus subtilis.
J Bacteriol. 2007 Aug;189(15):5642-51.
We have carried out a functional analysis of LysR family transcriptional regulators in Bacillus subtilis. The cell density of cultures of a yofA insertion mutant declined sharply after the end of exponential growth, as measured by optical density at 600 nm. Complementation in trans and analysis of isopropyl-beta-d-thiogalactopyranoside (IPTG)-dependent growth of an inducible yofA strain confirmed that YofA contributes to the cell density of a culture after the end of exponential growth. Microscopic observation suggested that cell division is inhibited or delayed in the yofA mutant during entry into stationary phase. Analysis of the transcription of cell division genes revealed that the expression of ftsW is inhibited in yofA mutants, and overexpression of yofA, driven by a multiple-copy plasmid, enhances the induction of ftsW expression. These results suggest that YofA is required for the final round of cell division before entry into stationary phase and that YofA positively regulates ftsW expression. The defects caused by mutation of yofA were suppressed in strains carrying P(spac)-ftsW in the presence of IPTG. Furthermore, maximal expression of yofA was observed at the onset of stationary phase, which coincided with the maximal ftsW expression. Our data indicate that YofA is involved in cell division through positive regulation of the expression of ftsW in B. subtilis. [Abstract/Link to Full Text]

Kawakami R, Sakuraba H, Ohshima T
Gene cloning and characterization of the very large NAD-dependent l-glutamate dehydrogenase from the psychrophile Janthinobacterium lividum, isolated from cold soil.
J Bacteriol. 2007 Aug;189(15):5626-33.
NAD-dependent l-glutamate dehydrogenase (NAD-GDH) activity was detected in cell extract from the psychrophile Janthinobacterium lividum UTB1302, which was isolated from cold soil and purified to homogeneity. The native enzyme (1,065 kDa, determined by gel filtration) is a homohexamer composed of 170-kDa subunits (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Consistent with these findings, gene cloning and sequencing enabled deduction of the amino acid sequence of the subunit, which proved to be comprised of 1,575 amino acids with a combined molecular mass of 169,360 Da. The enzyme from this psychrophile thus appears to belong to the GDH family characterized by very large subunits, like those expressed by Streptomyces clavuligerus and Pseudomonas aeruginosa (about 180 kDa). The entire amino acid sequence of the J. lividum enzyme showed about 40% identity with the sequences from S. clavuligerus and P. aeruginosa enzymes, but the central domains showed higher homology (about 65%). Within the central domain, the residues related to substrate and NAD binding were highly conserved, suggesting that this is the enzyme's catalytic domain. In the presence of NAD, but not in the presence of NADP, this GDH exclusively catalyzed the oxidative deamination of l-glutamate. The stereospecificity of the hydride transfer to NAD was pro-S, which is the same as that of the other known GDHs. Surprisingly, NAD-GDH activity was markedly enhanced by the addition of various amino acids, such as l-aspartate (1,735%) and l-arginine (936%), which strongly suggests that the N- and/or C-terminal domains play regulatory roles and are involved in the activation of the enzyme by these amino acids. [Abstract/Link to Full Text]

Gómez-Gil L, Kumar P, Barriault D, Bolin JT, Sylvestre M, Eltis LD
Characterization of biphenyl dioxygenase of Pandoraea pnomenusa B-356 as a potent polychlorinated biphenyl-degrading enzyme.
J Bacteriol. 2007 Aug;189(15):5705-15.
Biphenyl dioxygenase (BPDO) catalyzes the aerobic transformation of biphenyl and various polychlorinated biphenyls (PCBs). In three different assays, BPDO(B356) from Pandoraea pnomenusa B-356 was a more potent PCB-degrading enzyme than BPDO(LB400) from Burkholderia xenovorans LB400 (75% amino acid sequence identity), transforming nine congeners in the following order of preference: 2,3',4-trichloro approximately 2,3,4'-trichloro > 3,3'-dichloro > 2,4,4'-trichloro > 4,4'-dichloro approximately 2,2'-dichloro > 2,6-dichloro > 2,2',3,3'-tetrachloro approximately 2,2',5,5'-tetrachloro. Except for 2,2',5,5'-tetrachlorobiphenyl, BPDO(B356) transformed each congener at a higher rate than BPDO(LB400). The assays used either whole cells or purified enzymes and either individual congeners or mixtures of congeners. Product analyses established previously unrecognized BPDO(B356) activities, including the 3,4-dihydroxylation of 2,6-dichlorobiphenyl. BPDO(LB400) had a greater apparent specificity for biphenyl than BPDO(B356) (k(cat)/K(m) = 2.4 x 10(6) +/- 0.7 x 10(6) M(-1) s(-1) versus k(cat)/K(m) = 0.21 x 10(6) +/- 0.04 x 10(6) M(-1) s(-1)). However, the latter transformed biphenyl at a higher maximal rate (k(cat) = 4.1 +/- 0.2 s(-1) versus k(cat) = 0.4 +/- 0.1 s(-1)). A variant of BPDO(LB400) containing four active site residues of BPDO(B356) transformed para-substituted congeners better than BPDO(LB400). Interestingly, a substitution remote from the active site, A267S, increased the enzyme's preference for meta-substituted congeners. Moreover, this substitution had a greater effect on the kinetics of biphenyl utilization than substitutions in the substrate-binding pocket. In all variants, the degree of coupling between congener depletion and O(2) consumption was approximately proportional to congener depletion. At 2.4-A resolution, the crystal structure of the BPDO(B356)-2,6-dichlorobiphenyl complex, the first crystal structure of a BPDO-PCB complex, provided additional insight into the reactivity of this isozyme with this congener, as well as into the differences in congener preferences of the BPDOs. [Abstract/Link to Full Text]

Rasouly A, Shenhar Y, Ron EZ
Thermoregulation of Escherichia coli hchA transcript stability.
J Bacteriol. 2007 Aug;189(15):5779-81.
The conserved chaperone Hsp31 of Escherichia coli is transcribed at low temperatures by sigma(S) and repressed by H-NS, whereas at high temperature, transcription is by sigma70 independently of both sigma(S) and H-NS. Here we present evidence for an additional, novel, temperature-dependent control of Hsp31 expression by increased transcript stability. [Abstract/Link to Full Text]

Belle JJ, Casey A, Courcelle CT, Courcelle J
Inactivation of the DnaB helicase leads to the collapse and degradation of the replication fork: a comparison to UV-induced arrest.
J Bacteriol. 2007 Aug;189(15):5452-62.
Replication forks face a variety of structurally diverse impediments that can prevent them from completing their task. The mechanism by which cells overcome these hurdles is likely to vary depending on the nature of the obstacle and the strand in which the impediment is encountered. Both UV-induced DNA damage and thermosensitive replication proteins have been used in model systems to inhibit DNA replication and characterize the mechanism by which it recovers. In this study, we examined the molecular events that occur at replication forks following inactivation of a thermosensitive DnaB helicase and found that they are distinct from those that occur following arrest at UV-induced DNA damage. Following UV-induced DNA damage, the integrity of replication forks is maintained and protected from extensive degradation by RecA, RecF, RecO, and RecR until replication can resume. By contrast, inactivation of DnaB results in extensive degradation of the nascent and leading-strand template DNA and a loss of replication fork integrity as monitored by two-dimensional agarose gel analysis. The degradation that occurs following DnaB inactivation partially depends on several genes, including recF, recO, recR, recJ, recG, and xonA. Furthermore, the thermosensitive DnaB allele prevents UV-induced DNA degradation from occurring following arrest even at the permissive temperature, suggesting a role for DnaB prior to loading of the RecFOR proteins. We discuss these observations in relation to potential models for both UV-induced and DnaB(Ts)-mediated replication inhibition. [Abstract/Link to Full Text]

Ramírez-Trujillo JA, Encarnación S, Salazar E, de los Santos AG, Dunn MF, Emerich DW, Calva E, Hernández-Lucas I
Functional characterization of the Sinorhizobium meliloti acetate metabolism genes aceA, SMc00767, and glcB.
J Bacteriol. 2007 Aug;189(16):5875-84.
The genes encoding malate synthase (glcB) and isocitrate lyase (aceA) and a 240-bp open reading frame (SMc00767) located downstream of aceA were isolated and functionally characterized in Sinorhizobium meliloti. Independent and double interposon mutants of each gene were constructed, and the corresponding phenotypes were analyzed. aceA mutants failed to grow on acetate, and mutants deficient in SMc00767 were also affected in acetate utilization. In contrast, mutants deficient in glcB grew on acetate similar to wild-type strain Rm5000. Complementation experiments showed that aceA and SMc00767 gene constructs were able to restore the growth on acetate in the corresponding single mutants. aceA-glcB, aceA-SMc00767, and glcB-SMc00767 double knockouts were also unable to grow on acetate, but this ability was recovered when the wild-type aceA-glcB or aceA-SMc00767 loci were introduced into the double mutants. These data confirm the functional role of aceA and SMc00767 and show that glcB, in the absence of SMc00767, is required for acetate metabolism. Isocitrate lyase and malate synthase activities were measured in strain Rm5000, the mutant derivatives, and complemented strains. aceA and glcB were able to complement the enzymatic activity lacking in the corresponding single mutants. The enzymatic activities also showed that SMc00767 represses the activity of isocitrate lyase in cells grown on acetate. Gene fusions confirmed the repressor role of SMc00767, which regulates aceA expression at the transcriptional level. Comparison of the transcriptional profiles of the SMc00767 mutant and wild-type strain Rm5000 showed that SMc00767 represses the expression of a moderate number of open reading frames, including aceA; thus, we propose that SMc00767 is a novel repressor involved in acetate metabolism in S. meliloti. Genetic and functional analyses indicated that aceA and SMc00767 constitute a functional two-gene operon, which is conserved in other alpha-proteobacteria. Alfalfa plants infected with the aceA and glcB mutants were not impaired in nodulation or nitrogen fixation, and so the glyoxylate cycle is not required in the Rhizobium-legume symbiosis. [Abstract/Link to Full Text]

Standish AJ, Stroeher UH, Paton JC
The pneumococcal two-component signal transduction system RR/HK06 regulates CbpA and PspA by two distinct mechanisms.
J Bacteriol. 2007 Aug;189(15):5591-600.
We have previously shown that CbpA, a major pneumococcal virulence factor, is regulated by the two-component signal transduction system RR/HK06 (A. J. Standish, U. H. Stroeher, and J. C. Paton, Proc. Natl. Acad. Sci. USA 102:7701-7706, 2005). However, additional unidentified regulated factors appeared to be responsible for differences in adherence and the ability of Streptococcus pneumoniae to cause disease in a mouse model. Here, we identified a number of other regulated genes by overexpressing the system. cbpA, along with a cotranscribed upstream gene, showed substantial increases in expression when RR06 was overexpressed in S. pneumoniae strains D39 and TIGR4. However, there were no other similarities between these strains. In D39, rr06 overexpression decreased expression of numerous factors, including the major virulence factor gene pspA. Further investigation of cbpA regulation by RR/HK06, using mutants with mutations in both HK06 and RR06, suggested that rather than the norm, cbpA transcription was activated when RR06 was in the nonphosphorylated form. Although other factors, such as pspA and gls24, are regulated by this system, these genes appear to be repressed when RR06 is in its phosphorylated form. [Abstract/Link to Full Text]

Baker CS, Eöry LA, Yakhnin H, Mercante J, Romeo T, Babitzke P
CsrA inhibits translation initiation of Escherichia coli hfq by binding to a single site overlapping the Shine-Dalgarno sequence.
J Bacteriol. 2007 Aug;189(15):5472-81.
Csr (carbon storage regulation) of Escherichia coli is a global regulatory system that consists of CsrA, a homodimeric RNA binding protein, two noncoding small RNAs (sRNAs; CsrB and CsrC) that function as CsrA antagonists by sequestering this protein, and CsrD, a specificity factor that targets CsrB and CsrC for degradation by RNase E. CsrA inhibits translation initiation of glgC, cstA, and pgaA by binding to their leader transcripts and preventing ribosome binding. Translation inhibition is thought to contribute to the observed mRNA destabilization. Each of the previously known target transcripts contains multiple CsrA binding sites. A position-specific weight matrix search program was developed using known CsrA binding sites in mRNA. This search tool identified a potential CsrA binding site that overlaps the Shine-Dalgarno sequence of hfq, a gene that encodes an RNA chaperone that mediates sRNA-mRNA interactions. This putative CsrA binding site matched the SELEX-derived binding site consensus sequence in 8 out of 12 positions. Results from gel mobility shift and footprint assays demonstrated that CsrA binds specifically to this site in the hfq leader transcript. Toeprint and cell-free translation results indicated that bound CsrA inhibits Hfq synthesis by competitively blocking ribosome binding. Disruption of csrA caused elevated expression of an hfq'-'lacZ translational fusion, while overexpression of csrA inhibited expression of this fusion. We also found that hfq mRNA is stabilized upon entry into stationary-phase growth by a CsrA-independent mechanism. The interaction of CsrA with hfq mRNA is the first example of a CsrA-regulated gene that contains only one CsrA binding site. [Abstract/Link to Full Text]

Shi L, Li JH, Cheng Y, Wang L, Chen WL, Zhang CC
Two genes encoding protein kinases of the HstK family are involved in synthesis of the minor heterocyst-specific glycolipid in the cyanobacterium Anabaena sp. strain PCC 7120.
J Bacteriol. 2007 Jul;189(14):5075-81.
The filamentous cyanobacterium Anabaena sp. strain PCC 7120 can fix N(2) under oxic conditions, and the activity of nitrogen fixation occurs exclusively in heterocysts, cells differentiated from vegetative cells in response to a limitation of a combined-nitrogen source in the growth medium. At the late stages of heterocyst differentiation, an envelope layer composed of two glycolipids is formed to limit the entry of oxygen so that the oxygen-sensitive nitrogenase can function. The genome of Anabaena sp. strain PCC 7120 possesses a family of 13 genes (the hstK family), all encoding proteins with a putative Ser/Thr kinase domain at their N termini and a His-kinase domain at their C termini. In this study, we showed that the double mutant D4.3 strain, in which two members of this gene family, pkn44 (all1625) and pkn30 (all3691), were both inactivated, failed to fix N(2) in the presence of oxygen (Fox(-)). In an environment without oxygen, a low level of nitrogenase activity was detectable (Fix(+)). Heterocyst development in the mutant D4.3 was delayed by 24 h and arrested at a relatively early stage without the formation of the glycolipid layer (Hgl(-)). Only the minor species of the two heterocyst-specific glycolipids (HGLs) was missing in the mutant. We propose that DevH, a putative transcription factor, coordinates the synthesis of both HGLs, while Pkn44/Pkn30 and the previously characterized PrpJ may represent two distinct regulatory pathways involved in the synthesis of the minor HGL and the major HGL, respectively. [Abstract/Link to Full Text]

Jain S, Goldberg MB
Requirement for YaeT in the outer membrane assembly of autotransporter proteins.
J Bacteriol. 2007 Jul;189(14):5393-8.
Autotransporters constitute the largest group of secreted proteins in gram-negative bacteria. Autotransporter secretion involves the insertion of a carboxy-terminal beta barrel into and the translocation of an amino-terminal domain across the outer membrane. Here, we demonstrate that secretion of autotransporters from several organisms requires the outer membrane assembly factor YaeT. [Abstract/Link to Full Text]

Legaree BA, Adams CB, Clarke AJ
Overproduction of penicillin-binding protein 2 and its inactive variants causes morphological changes and lysis in Escherichia coli.
J Bacteriol. 2007 Jul;189(14):4975-83.
Penicillin-binding protein 2 (PBP 2) has long been known to be essential for rod-shaped morphology in gram-negative bacteria, including Escherichia coli and Pseudomonas aeruginosa. In the course of earlier studies with P. aeruginosa PBP 2, we observed that E. coli was sensitive to the overexpression of its gene, pbpA. In this study, we examined E. coli overproducing both P. aeruginosa and E. coli PBP 2. Growth of cells entered a stationary phase soon after induction of gene expression, and cells began to lyse upon prolonged incubation. Concomitant with the growth retardation, cells were observed to have changed morphologically from typical rods into enlarged spheres. Inactive derivatives of the PBP 2s were engineered, involving site-specific replacement of their catalytic Ser residues with Ala in their transpeptidase module. Overproduction of these inactive PBPs resulted in identical effects. Likewise, overproduction of PBP 2 derivatives possessing only their N-terminal non-penicillin-binding module (i.e., lacking their C-terminal transpeptidase module) produced similar effects. However, E. coli overproducing engineered derivatives of PBP 2 lacking their noncleavable, N-terminal signal sequence and membrane anchor were found to grow and divide at the same rate as control cells. The morphological effects and lysis were also eliminated entirely when overproduction of PBP 2 and variants was conducted with E. coli MHD79, a strain lacking six lytic transglycosylases. A possible interaction between the N-terminal domain of PBP 2 and lytic transglycosylases in vivo through the formation of multienzyme complexes is discussed. [Abstract/Link to Full Text]

Wickstrum JR, Skredenske JM, Kolin A, Jin DJ, Fang J, Egan SM
Transcription activation by the DNA-binding domain of the AraC family protein RhaS in the absence of its effector-binding domain.
J Bacteriol. 2007 Jul;189(14):4984-93.
The Escherichia coli L-rhamnose-responsive transcription activators RhaS and RhaR both consist of two domains, a C-terminal DNA-binding domain and an N-terminal dimerization domain. Both function as dimers and only activate transcription in the presence of L-rhamnose. Here, we examined the ability of the DNA-binding domains of RhaS (RhaS-CTD) and RhaR (RhaR-CTD) to bind to DNA and activate transcription. RhaS-CTD and RhaR-CTD were both shown by DNase I footprinting to be capable of binding specifically to the appropriate DNA sites. In vivo as well as in vitro transcription assays showed that RhaS-CTD could activate transcription to high levels, whereas RhaR-CTD was capable of only very low levels of transcription activation. As expected, RhaS-CTD did not require the presence of L-rhamnose to activate transcription. The upstream half-site at rhaBAD and the downstream half-site at rhaT were found to be the strongest of the known RhaS half-sites, and a new putative RhaS half-site with comparable strength to known sites was identified. Given that cyclic AMP receptor protein (CRP), the second activator required for full rhaBAD expression, cannot activate rhaBAD expression in a DeltarhaS strain, it was of interest to test whether CRP could activate transcription in combination with RhaS-CTD. We found that RhaS-CTD allowed significant activation by CRP, both in vivo and in vitro, although full-length RhaS allowed somewhat greater CRP activation. We conclude that RhaS-CTD contains all of the determinants necessary for transcription activation by RhaS. [Abstract/Link to Full Text]

Varhimo E, Savijoki K, Jalava J, Kuipers OP, Varmanen P
Identification of a novel streptococcal gene cassette mediating SOS mutagenesis in Streptococcus uberis.
J Bacteriol. 2007 Jul;189(14):5210-22.
Streptococci have been considered to lack the classical SOS response, defined by increased mutation after UV exposure and regulation by LexA. Here we report the identification of a potential self-regulated SOS mutagenesis gene cassette in the Streptococcaceae family. Exposure to UV light was found to increase mutations to antibiotic resistance in Streptococcus uberis cultures. The mutational spectra revealed mainly G:C-->A:T transitions, and Northern analyses demonstrated increased expression of a Y-family DNA polymerase resembling UmuC under DNA-damaging conditions. In the absence of the Y-family polymerase, S. uberis cells were sensitive to UV light and to mitomycin C. Furthermore, the UV-induced mutagenesis was almost completely abolished in cells deficient in the Y-family polymerase. The gene encoding the Y-family polymerase was localized in a four-gene operon including two hypothetical genes and a gene encoding a HdiR homolog. Electrophoretic mobility shift assays demonstrated that S. uberis HdiR binds specifically to an inverted repeat sequence in the promoter region of the four-gene operon. Database searches revealed conservation of the gene cassette in several Streptococcus species, including at least one genome each of Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus mitis, Streptococcus sanguinis, and Streptococcus thermophilus strains. In addition, the umuC operon was localized in several mobile DNA elements of Streptococcus and Lactococcus species. We conclude that the hdiR-umuC-ORF3-ORF4 operon represents a novel gene cassette capable of mediating SOS mutagenesis among members of the Streptococcaceae. [Abstract/Link to Full Text]

Davidsen T, Tuven HK, Bjørås M, Rødland EA, Tønjum T
Genetic interactions of DNA repair pathways in the pathogen Neisseria meningitidis.
J Bacteriol. 2007 Aug;189(15):5728-37.
The current increase in the incidence and severity of infectious diseases mandates improved understanding of the basic biology and DNA repair profiles of virulent microbes. In our studies of the major pathogen and model organism Neisseria meningitidis, we constructed a panel of mutants inactivating genes involved in base excision repair, mismatch repair, nucleotide excision repair (NER), translesion synthesis, and recombinational repair pathways. The highest spontaneous mutation frequency among the N. meningitidis single mutants was found in the MutY-deficient strain as opposed to mutS mutants in Escherichia coli, indicating a role for meningococcal MutY in antibiotic resistance development. Recombinational repair was recognized as a major pathway counteracting methyl methanesulfonate-induced alkylation damage in the N. meningitidis. In contrast to what has been shown in other species, meningococcal NER did not contribute significantly to repair of alkylation-induced DNA damage, and meningococcal recombinational repair may thus be one of the main pathways for removal of abasic (apurinic/apyrimidinic) sites and strand breaks in DNA. Conversely, NER was identified as the main meningococcal defense pathway against UV-induced DNA damage. N. meningitidis RecA single mutants exhibited only a moderate decrease in survival after UV exposure as opposed to E. coli recA strains, which are extremely UV sensitive, possibly reflecting the lack of a meningococcal SOS response. In conclusion, distinct differences between N. meningitidis and established DNA repair characteristics in E. coli and other species were identified. [Abstract/Link to Full Text]

McKenzie NL, Nodwell JR
Phosphorylated AbsA2 negatively regulates antibiotic production in Streptomyces coelicolor through interactions with pathway-specific regulatory gene promoters.
J Bacteriol. 2007 Jul;189(14):5284-92.
The AbsA two-component signal transduction system, comprised of the sensor kinase AbsA1 and the response regulator AbsA2, acts as a negative regulator of antibiotic production in Streptomyces coelicolor, for which the phosphorylated form of AbsA2 (AbsA2 approximately P) is the agent of repression. In this study, we used chromatin immunoprecipitation to show that AbsA2 binds the promoter regions of actII-ORF4, cdaR, and redZ, which encode pathway-specific activators for actinorhodin, calcium-dependent antibiotic, and undecylprodigiosin, respectively. We confirm that these interactions also occur in vitro and that the binding of AbsA2 to each gene is enhanced by phosphorylation. Induced expression of actII-ORF4 and redZ in the hyperrepressive absA1 mutant (C542) brought about pathway-specific restoration of actinorhodin and undecylprodigiosin production, respectively. Our results suggest that AbsA2 approximately P interacts with as many as four sites in the region that includes the actII-ORF4 promoter. These data suggest that AbsA2 approximately P inhibits antibiotic production by directly interfering with the expression of pathway-specific regulators of antibiotic biosynthetic gene clusters. [Abstract/Link to Full Text]

Han X, Kennan RM, Parker D, Davies JK, Rood JI
Type IV fimbrial biogenesis is required for protease secretion and natural transformation in Dichelobacter nodosus.
J Bacteriol. 2007 Jul;189(14):5022-33.
The objective of this study was to develop an understanding of the molecular mechanisms by which type IV fimbrial biogenesis, natural transformation, and protease secretion are linked in the ovine foot rot pathogen, Dichelobacter nodosus. We have shown that like the D. nodosus fimbrial subunit FimA, the pilin-like protein PilE and the FimN, FimO, and FimP proteins, which are homologs of PilB, PilC, and PilD from Pseudomonas aeruginosa, are essential for fimbrial biogenesis and natural transformation, indicating that transformation requires an intact type IV fimbrial apparatus. The results also showed that extracellular protease secretion in the fimN, fimO, fimP, and pilE mutants was significantly reduced, which represents the first time that PilB, PilC, and PilE homologs have been shown to be required for the secretion of unrelated extracellular proteins in a type IV fimbriate bacterium. Quantitative real-time PCR analysis of the three extracellular protease genes aprV2, aprV5, and bprV showed that the effects on protease secretion were not mediated at the transcriptional level. Bioinformatic analysis did not identify a classical type II secretion system, and the putative fimbrial biogenesis gene pilQ was the only outer membrane secretin gene identified. Based on these results, it is postulated that in D. nodosus, protease secretion occurs by a type II secretion-related process that directly involves components of the type IV fimbrial biogenesis machinery, which represents the only type II secretion system encoded by the small genome of this highly evolved pathogen. [Abstract/Link to Full Text]

Varma A, de Pedro MA, Young KD
FtsZ directs a second mode of peptidoglycan synthesis in Escherichia coli.
J Bacteriol. 2007 Aug;189(15):5692-704.
Certain penicillin binding protein mutants of Escherichia coli grow with spirillum-like morphologies when the FtsZ protein is inhibited, suggesting that FtsZ might govern aspects of cell wall growth other than those strictly associated with septation. While investigating the mechanism of spiral cell formation, we discovered conditions for visualizing this second function of FtsZ. Normally, inhibiting the cytoskeleton protein MreB forces E. coli cells to grow as smoothly enlarging spheres from which the poles disappear, yielding coccoid or lemon-shaped forms. However, when FtsZ and MreB were inhibited simultaneously in a strain lacking PBP 5 and PBP 7, the resulting cells ballooned outward but retained conspicuous rod-shaped extensions at sites representing the original poles. This visual phenotype was paralleled by the biochemistry of sacculus growth. Muropeptides are usually inserted homogeneously into the lateral cell walls, but when FtsZ polymerization was inhibited, the incorporation of new material occurred mainly in the central regions of cells and was significantly lower in those portions of side walls abutting a pole. Thus, reduced precursor incorporation into side walls near the poles explained why these regions retained their rod-like morphology while the rest of the cell grew spherically. Also, inhibiting FtsZ increased the amount of pentapeptides in sacculi by about one-third. Finally, the MreB protein directed the helical or diagonal incorporation of new peptidoglycan into the wall, but the location of that incorporation depended on whether FtsZ was active. In sum, the results indicate that in addition to nucleating cell septation in E. coli, FtsZ can direct the insertion of new peptidoglycan into portions of the lateral wall. [Abstract/Link to Full Text]

Lane MC, Simms AN, Mobley HL
complex interplay between type 1 fimbrial expression and flagellum-mediated motility of uropathogenic Escherichia coli.
J Bacteriol. 2007 Aug;189(15):5523-33.
Type 1 fimbriae and flagella have been previously shown to contribute to the virulence of uropathogenic Escherichia coli (UPEC) within the urinary tract. In this study, the relationship between motility and type 1 fimbrial expression was tested for UPEC strain CFT073 by examining the phenotypic effect of fimbrial expression on motility and the effect that induction of motility has on type 1 fimbrial expression. While constitutive expression of type 1 fimbriae resulted in a significant decrease in motility and flagellin expression (P < 0.0001), a loss of type 1 fimbrial expression did not result in increased motility. Additionally, hypermotility and flagellar gene over- and underexpression were not observed to affect the expression of type 1 fimbriae. Hence, it appeared that the relationship between type 1 fimbrial expression and motility is unidirectional, where the overexpression of type 1 fimbriae dramatically affects motility and flagellum expression but not vice versa. Moreover, the constitutive expression of type 1 fimbriae in UPEC cystitis isolate F11 and the laboratory strain E. coli K-12 MG1655 also resulted in decreased motility, suggesting that this phenomenon is not specific to CFT073 or UPEC in general. Lastly, by analyzing the repression of motility caused by constitutive type 1 fimbrial expression, it was concluded that the synthesis and presence of type 1 fimbriae at the bacterial surface is only partially responsible for the repression of motility, as evidenced by the partial restoration of motility in the CFT073 fim L-ON DeltafimAICDFGH mutant. Altogether, these data provide further insight into the complex interplay between type 1 fimbrial expression and flagellum-mediated motility. [Abstract/Link to Full Text]

Berleman JE, Kirby JR
multicellular development in Myxococcus xanthus is stimulated by predator-prey interactions.
J Bacteriol. 2007 Aug;189(15):5675-82.
Myxococcus xanthus is a predatory bacterium that exhibits complex social behavior. The most pronounced behavior is the aggregation of cells into raised fruiting body structures in which cells differentiate into stress-resistant spores. In the laboratory, monocultures of M. xanthus at a very high density will reproducibly induce hundreds of randomly localized fruiting bodies when exposed to low nutrient availability and a solid surface. In this report, we analyze how M. xanthus fruiting body development proceeds in a coculture with suitable prey. Our analysis indicates that when prey bacteria are provided as a nutrient source, fruiting body aggregation is more organized, such that fruiting bodies form specifically after a step-down or loss of prey availability, whereas a step-up in prey availability inhibits fruiting body formation. This localization of aggregates occurs independently of the basal nutrient levels tested, indicating that starvation is not required for this process. Analysis of early developmental signaling relA and asgD mutants indicates that they are capable of forming fruiting body aggregates in the presence of prey, demonstrating that the stringent response and A-signal production are surprisingly not required for the initiation of fruiting behavior. However, these strains are still defective in differentiating to spores. We conclude that fruiting body formation does not occur exclusively in response to starvation and propose an alternative model in which multicellular development is driven by the interactions between M. xanthus cells and their cognate prey. [Abstract/Link to Full Text]

Ogasawara H, Ishida Y, Yamada K, Yamamoto K, Ishihama A
PdhR (pyruvate dehydrogenase complex regulator) controls the respiratory electron transport system in Escherichia coli.
J Bacteriol. 2007 Aug;189(15):5534-41.
The pyruvate dehydrogenase (PDH) multienzyme complex plays a key role in the metabolic interconnection between glycolysis and the citric acid cycle. Transcription of the Escherichia coli genes for all three components of the PDH complex in the pdhR-aceEF-lpdA operon is repressed by the pyruvate-sensing PdhR, a GntR family transcription regulator, and derepressed by pyruvate. After a systematic search for the regulation targets of PdhR using genomic systematic evolution of ligands by exponential enrichment (SELEX), we have identified two novel targets, ndh, encoding NADH dehydrogenase II, and cyoABCDE, encoding the cytochrome bo-type oxidase, both together forming the pathway of respiratory electron transport downstream from the PDH cycle. PDH generates NADH, while Ndh and CyoABCDE together transport electrons from NADH to oxygen. Using gel shift and DNase I footprinting assays, the PdhR-binding site (PdhR box) was defined, which includes a palindromic consensus sequence, ATTGGTNNNACCAAT. The binding in vitro of PdhR to the PdhR box decreased in the presence of pyruvate. Promoter assays in vivo using a two-fluorescent-protein vector also indicated that the newly identified operons are repressed by PdhR and derepressed by the addition of pyruvate. Taken together, we propose that PdhR is a master regulator for controlling the formation of not only the PDH complex but also the respiratory electron transport system. [Abstract/Link to Full Text]

Anderson DS, Adhikari P, Weaver KD, Crumbliss AL, Mietzner TA
The Haemophilus influenzae hFbpABC Fe3+ transporter: analysis of the membrane permease and development of a gallium-based screen for mutants.
J Bacteriol. 2007 Jul;189(14):5130-41.
The obligate human pathogen Haemophilus influenzae utilizes a siderophore-independent (free) Fe(3+) transport system to obtain this essential element from the host iron-binding protein transferrin. The hFbpABC transporter is a binding protein-dependent ABC transporter that functions to shuttle (free) Fe(3+) through the periplasm and across the inner membrane of H. influenzae. This investigation focuses on the structure and function of the hFbpB membrane permease component of the transporter, a protein that has eluded prior characterization. Based on multiple-sequence alignments between permease orthologs, a series of site-directed mutations targeted at residues within the two conserved permease motifs were generated. The hFbpABC transporter was expressed in a siderophore-deficient Escherichia coli background, and effects of mutations were analyzed using growth rescue and radiolabeled (55)Fe(3+) transport assays. Results demonstrate that mutation of the invariant glycine (G418A) within motif 2 led to attenuated transport activity, while mutation of the invariant glycine (G155A/V/E) within motif 1 had no discernible effect on activity. Individual mutations of well-conserved leucines (L154D and L417D) led to attenuated and null transport activities, respectively. As a complement to site-directed methods, a mutant screen based on resistance to the toxic iron analog gallium, an hFbpABC inhibitor, was devised. The screen led to the identification of several significant hFbpB mutations; V497I, I174F, and S475I led to null transport activities, while S146Y resulted in attenuated activity. Significant residues were mapped to a topological model of the hFbpB permease, and the implications of mutations are discussed in light of structural and functional data from related ABC transporters. [Abstract/Link to Full Text]

Halsey KH, Doughty DM, Sayavedra-Soto LA, Bottomley PJ, Arp DJ
Evidence for modified mechanisms of chloroethene oxidation in Pseudomonas butanovora mutants containing single amino acid substitutions in the hydroxylase alpha-subunit of butane monooxygenase.
J Bacteriol. 2007 Jul;189(14):5068-74.
The properties of oxidation of dichloroethene (DCE) and trichloroethylene (TCE) by three mutant strains of Pseudomonas butanovora containing single amino acid substitutions in the alpha-subunit of butane monooxygenase hydroxylase (BMOH-alpha) were compared to the properties of the wild-type strain (Rev WT). The rates of oxidation of three chloroethenes (CEs) were reduced in mutant strain G113N and corresponded with a lower maximum rate of butane oxidation. The rate of TCE degradation was reduced by one-half in mutant strain L279F, whereas the rates of DCE oxidation were the same as those in Rev WT. Evidence was obtained that the composition of products of CE oxidation differed between Rev WT and some of the mutant strains. For example, while Rev WT released nearly all available chlorine stoichiometrically during CE oxidation, strain F321Y released about 40% of the chlorine during 1,2-cis-DCE and TCE oxidation, and strain G113N released between 14 and 25% of the available chlorine during oxidation of DCE and 56% of the available chlorine during oxidation of TCE. Whereas Rev WT, strain L279F, and strain F321Y formed stoichiometric amounts of 1,2-cis-DCE epoxide during oxidation of 1,2-cis-DCE, only about 50% of the 1,2-cis-DCE oxidized by strain G113N was detected as the epoxide. Evidence was obtained that 1,2-cis-DCE epoxide was a substrate for butane monooxygenase (BMO) that was oxidized after the parent compound was consumed. Yet all of the mutant strains released less than 40% of the available 1,2-cis-DCE chlorine, suggesting that they have altered activity towards the epoxide. In addition, strain G113N was unable to degrade the epoxide. TCE epoxide was detected during exposure of Rev WT and strain F321Y to TCE but was not detected with strains L279F and G113N. Lactate-dependent O(2) uptake rates were differentially affected by DCE degradation in the mutant strains, providing evidence that some products released by the altered BMOs reduced the impact of CE on cellular toxicity. The use of CEs as substrates in combination with P. butanovora BMOH-alpha mutants might allow insights into the catalytic mechanism of BMO to be obtained. [Abstract/Link to Full Text]

Schaaf S, Bott M
Target genes and DNA-binding sites of the response regulator PhoR from Corynebacterium glutamicum.
J Bacteriol. 2007 Jul;189(14):5002-11.
The two-component signal transduction system PhoRS of Corynebacterium glutamicum is involved in the phosphate (P(i)) starvation response. To analyze the binding of unphosphorylated and phosphorylated PhoR to the promoters of phosphate starvation-inducible (psi) genes, this response regulator and the kinase domain of its cognate sensor, PhoS (MBP-PhoSDelta1-246), were overproduced and purified. MBP-PhoSDelta1-246 showed constitutive autophosphorylation activity, and a rapid phosphoryl group transfer from phosphorylated MBP-PhoSDelta1-246 to PhoR was observed. Gel mobility shift assays revealed that phosphorylation increases the DNA-binding affinity of PhoR. The affinity of PhoR approximately P to different promoters varied and decreased in the order pstSCAB > phoRS > phoC > ushA > porB > ugpA > pitA > nucH and phoH1 > glpQ1. The binding sites in front of pstSCAB and phoRS were localized at positions -194 to -176 and -61 to -43 upstream of the transcriptional start sites, respectively. Alignment of these two 19-bp binding sites revealed a high identity in the 5'-terminal part, but not in the 3'-terminal part. As many OmpR-type response regulators bind to direct repeats, the 19-bp sequence might be interpreted as a loosely conserved 8-bp direct repeat separated by 3 bp. This idea was supported by the fact that the highest binding affinity was observed with a perfect 8-bp direct repeat of the sequence CCTGTGAAaatCCTGTGAA. Inspection of the other target promoters revealed sequences with some similarity to this binding motif, which might represent PhoR binding sites. The in vivo relevance of the PhoR-binding site within the phoRS promoter was supported by reporter gene studies. [Abstract/Link to Full Text]

Nord D, Torrents E, Sjöberg BM
A functional homing endonuclease in the Bacillus anthracis nrdE group I intron.
J Bacteriol. 2007 Jul;189(14):5293-301.
The essential Bacillus anthracis nrdE gene carries a self-splicing group I intron with a putative homing endonuclease belonging to the GIY-YIG family. Here, we show that the nrdE pre-mRNA is spliced and that the homing endonuclease cleaves an intronless nrdE gene 5 nucleotides (nt) upstream of the intron insertion site, producing 2-nt 3' extensions. We also show that the sequence required for efficient cleavage spans at least 4 bp upstream and 31 bp downstream of the cleaved coding strand. The position of the recognition sequence in relation to the cleavage position is as expected for a GIY-YIG homing endonuclease. Interestingly, nrdE genes from several other Bacillaceae were also susceptible to cleavage, with those of Bacillus cereus, Staphylococcus epidermidis (nrdE1), B. anthracis, and Bacillus thuringiensis serovar konkukian being better substrates than those of Bacillus subtilis, Bacillus lichenformis, and S. epidermidis (nrdE2). On the other hand, nrdE genes from Lactococcus lactis, Escherichia coli, Salmonella enterica serovar Typhimurium, and Corynebacterium ammoniagenes were not cleaved. Intervening sequences (IVSs) residing in protein-coding genes are often found in enzymes involved in DNA metabolism, and the ribonucleotide reductase nrdE gene is a frequent target for self-splicing IVSs. A comparison of nrdE genes from seven gram-positive low-G+C bacteria, two bacteriophages, and Nocardia farcinica showed five different insertion sites for self-splicing IVSs within the coding region of the nrdE gene. [Abstract/Link to Full Text]

Bailly X, Olivieri I, Brunel B, Cleyet-Marel JC, Béna G
Horizontal gene transfer and homologous recombination drive the evolution of the nitrogen-fixing symbionts of Medicago species.
J Bacteriol. 2007 Jul;189(14):5223-36.
Using nitrogen-fixing Sinorhizobium species that interact with Medicago plants as a model system, we aimed at clarifying how sex has shaped the diversity of bacteria associated with the genus Medicago on the interspecific and intraspecific scales. To gain insights into the diversification of these symbionts, we inferred a topology that includes the different specificity groups which interact with Medicago species, based on sequences of the nodulation gene cluster. Furthermore, 126 bacterial isolates were obtained from two soil samples, using Medicago truncatula and Medicago laciniata as host plants, to study the differentiation between populations of Sinorhizobium medicae, Sinorhizobium meliloti bv. meliloti, and S. meliloti bv. medicaginis. The former two can be associated with M. truncatula (among other species of Medicago), whereas the last organism is the specific symbiont of M. laciniata. These bacteria were characterized using a multilocus sequence analysis of four loci, located on the chromosome and on the two megaplasmids of S. meliloti. The phylogenetic results reveal that several interspecific horizontal gene transfers occurred during the diversification of Medicago symbionts. Within S. meliloti, the analyses show that nod genes specific to different host plants have spread to different genetic backgrounds through homologous recombination, preventing further divergence of the different ecotypes. Thus, specialization to different host plant species does not prevent the occurrence of gene flow among host-specific biovars of S. meliloti, whereas reproductive isolation between S. meliloti bv. meliloti and S. medicae is maintained even though these bacteria can cooccur in sympatry on the same individual host plants. [Abstract/Link to Full Text]

Torrents E, Grinberg I, Gorovitz-Harris B, Lundström H, Borovok I, Aharonowitz Y, Sjöberg BM, Cohen G
NrdR controls differential expression of the Escherichia coli ribonucleotide reductase genes.
J Bacteriol. 2007 Jul;189(14):5012-21.
Escherichia coli possesses class Ia, class Ib, and class III ribonucleotide reductases (RNR). Under standard laboratory conditions, the aerobic class Ia nrdAB RNR genes are well expressed, whereas the aerobic class Ib nrdEF RNR genes are poorly expressed. The class III RNR is normally expressed under microaerophilic and anaerobic conditions. In this paper, we show that the E. coli YbaD protein differentially regulates the expression of the three sets of genes. YbaD is a homolog of the Streptomyces NrdR protein. It is not essential for growth and has been renamed NrdR. Previously, Streptomyces NrdR was shown to transcriptionally regulate RNR genes by binding to specific 16-bp sequence motifs, NrdR boxes, located in the regulatory regions of its RNR operons. All three E. coli RNR operons contain two such NrdR box motifs positioned in their regulatory regions. The NrdR boxes are located near to or overlap with the promoter elements. DNA binding experiments showed that NrdR binds to each of the upstream regulatory regions. We constructed deletions in nrdR (ybaD) and showed that they caused high-level induction of transcription of the class Ib RNR genes but had a much smaller effect on induction of transcription of the class Ia and class III RNR genes. We propose a model for differential regulation of the RNR genes based on binding of NrdR to the regulatory regions. The model assumes that differences in the positions of the NrdR binding sites, and in the sequences of the motifs themselves, determine the extent to which NrdR represses the transcription of each RNR operon. [Abstract/Link to Full Text]

Brooijmans RJ, Poolman B, Schuurman-Wolters GK, de Vos WM, Hugenholtz J
Generation of a membrane potential by Lactococcus lactis through aerobic electron transport.
J Bacteriol. 2007 Jul;189(14):5203-9.
Lactococcus lactis, a facultative anaerobic lactic acid bacterium, is known to have an increased growth yield when grown aerobically in the presence of heme. We have now established the presence of a functional, proton motive force-generating electron transfer chain (ETC) in L. lactis under these conditions. Proton motive force generation in whole cells was measured using a fluorescent probe (3',3'-dipropylthiadicarbocyanine), which is sensitive to changes in membrane potential (Delta psi). Wild-type cells, grown aerobically in the presence of heme, generated a Delta psi even in the presence of the F(1)-F(o) ATPase inhibitor N,N'-dicyclohexylcarbodiimide, while a cytochrome bd-negative mutant strain (CydA Delta) did not. We also observed high oxygen consumption rates by membrane vesicles prepared from heme-grown cells, compared to CydA Delta cells, upon the addition of NADH. This demonstrates that NADH is an electron donor for the L. lactis ETC and demonstrates the presence of a membrane-bound NADH-dehydrogenase. Furthermore, we show that the functional respiratory chain is present throughout the exponential and late phases of growth. [Abstract/Link to Full Text]

Ballicora MA, Erben ED, Yazaki T, Bertolo AL, Demonte AM, Schmidt JR, Aleanzi M, Bejar CM, Figueroa CM, Fusari CM, Iglesias AA, Preiss J
Identification of regions critically affecting kinetics and allosteric regulation of the Escherichia coli ADP-glucose pyrophosphorylase by modeling and pentapeptide-scanning mutagenesis.
J Bacteriol. 2007 Jul;189(14):5325-33.
ADP-glucose pyrophosphorylase (ADP-Glc PPase) is the enzyme responsible for the regulation of bacterial glycogen synthesis. To perform a structure-function relationship study of the Escherichia coli ADP-Glc PPase enzyme, we studied the effects of pentapeptide insertions at different positions in the enzyme and analyzed the results with a homology model. We randomly inserted 15 bp in a plasmid with the ADP-Glc PPase gene. We obtained 140 modified plasmids with single insertions of which 21 were in the coding region of the enzyme. Fourteen of them generated insertions of five amino acids, whereas the other seven created a stop codon and produced truncations. Correlation of ADP-Glc PPase activity to these modifications validated the enzyme model. Six of the insertions and one truncation produced enzymes with sufficient activity for the E. coli cells to synthesize glycogen and stain in the presence of iodine vapor. These were in regions away from the substrate site, whereas the mutants that did not stain had alterations in critical areas of the protein. The enzyme with a pentapeptide insertion between Leu(102) and Pro(103) was catalytically competent but insensitive to activation. We postulate this region as critical for the allosteric regulation of the enzyme, participating in the communication between the catalytic and regulatory domains. [Abstract/Link to Full Text]

Hiron A, Borezée-Durant E, Piard JC, Juillard V
Only one of four oligopeptide transport systems mediates nitrogen nutrition in Staphylococcus aureus.
J Bacteriol. 2007 Jul;189(14):5119-29.
Oligopeptides internalized by oligopeptide permease (Opp) transporters play key roles in bacterial nutrition, signaling, and virulence. To date, two opp operons, opp-1 and opp-2, have been identified in Staphylococcus aureus. Systematic in silico analysis of 11 different S. aureus genomes revealed the existence of two new opp operons, opp-3 and opp-4, plus an opp-5A gene encoding a putative peptide-binding protein. With the exception of opp-4, the opp operons were present in all S. aureus strains. Within a single strain, the different opp operons displayed little sequence similarity and distinct genetic organization. Transcriptional studies showed that opp-1, opp-2, opp-3, and opp-4 operons were polycistronic and that opp-5A is monocistronic. We designed a minimal chemically defined medium for S. aureus RN6390 and showed that all opp genes were expressed but at different levels. Where tested, OppA protein production paralleled transcriptional profiles. opp-3, which encodes proteins most similar to known peptide transport proteins, displayed the highest expression level and was the only transporter to be regulated by specific amino acids, tyrosine and phenylalanine. Defined deletion mutants in one or several peptide permeases were constructed and tested for their capacity to grow in peptide-containing medium. Among the four putative Opp systems, Opp-3 was the only system able to provide oligopeptides for growth, ranging in length from 3 to 8 amino acids. Dipeptides were imported exclusively by DtpT, a proton-driven di- and tripeptide permease. These data provide a first complete inventory of the peptide transport systems opp and dtpT of S. aureus. Among them, the newly identified Opp-3 appears to be the main Opp system supplying the cell with peptides as nutritional sources. [Abstract/Link to Full Text]

Tori K, Kimizu M, Ishino S, Ishino Y
DNA polymerases BI and D from the hyperthermophilic archaeon Pyrococcus furiosus both bind to proliferating cell nuclear antigen with their C-terminal PIP-box motifs.
J Bacteriol. 2007 Aug;189(15):5652-7.
Proliferating cell nuclear antigen (PCNA) is the sliding clamp that is essential for the high processivity of DNA synthesis during DNA replication. Pyrococcus furiosus, a hyperthermophilic archaeon, has at least two DNA polymerases, polymerase BI (PolBI) and PolD. Both of the two DNA polymerases interact with the archaeal P. furiosus PCNA (PfuPCNA) and perform processive DNA synthesis in vitro. This phenomenon, in addition to the fact that both enzymes display 3'-5' exonuclease activity, suggests that both DNA polymerases work in replication fork progression. We demonstrated here that both PolBI and PolD functionally interact with PfuPCNA at their C-terminal PIP boxes. The mutant PolBI and PolD enzymes lacking the PIP-box sequence do not respond to the PfuPCNA at all in an in vitro primer extension reaction. This is the first experimental evidence that the PIP-box motif, located at the C termini of the archaeal DNA polymerases, is actually critical for PCNA binding to form a processive DNA-synthesizing complex. [Abstract/Link to Full Text]

Russell RM, Sharp FC, Rasko DA, Sperandio V
QseA and GrlR/GrlA regulation of the locus of enterocyte effacement genes in enterohemorrhagic Escherichia coli.
J Bacteriol. 2007 Jul;189(14):5387-92.
Transcription of the locus of enterocyte effacement (LEE) genes in enterohemorrhagic Escherichia coli (EHEC) is regulated by the LEE-encoded Ler and GrlR/GrlA proteins as well as the non-LEE-encoded regulator QseA. This work demonstrates that GrlR/GrlA activate LEE2 transcription in a Ler-independent fashion, whereas transcription of grlRA is activated by QseA in both Ler-dependent and -independent manners. [Abstract/Link to Full Text]


Recent Articles in Journal of Clinical Microbiology

Sharma D, Sethi S, Mehta SD, Sharma M
In-house growth-promoting transport system for Neisseria gonorrhoeae.
J Clin Microbiol. 2007 Aug;45(8):2743-4.
Eno powder (GlaxoSmithKline), an antacid preparation readily available over the counter, was used instead of a CO(2) generator for the growth of 15 strains of Neisseria gonorrhoeae obtained from men with urethritis. Due to its easy accessibility and low cost, Eno powder can be useful in developing countries for transporting clinical specimens from resource-poor peripheral labs to reference laboratories. [Abstract/Link to Full Text]

Holtfreter S, Grumann D, Schmudde M, Nguyen HT, Eichler P, Strommenger B, Kopron K, Kolata J, Giedrys-Kalemba S, Steinmetz I, Witte W, Bröker BM
Clonal distribution of superantigen genes in clinical Staphylococcus aureus isolates.
J Clin Microbiol. 2007 Aug;45(8):2669-80.
Staphylococcus aureus is both a successful human commensal and a major pathogen. The elucidation of the molecular determinants of virulence, in particular assessment of the contributions of the genetic background versus those of mobile genetic elements (MGEs), has proved difficult in this variable species. To address this, we simultaneously determined the genetic backgrounds (spa typing) and the distributions of all 19 known superantigens and the exfoliative toxins A and D (multiplex PCR) as markers for MGEs. Methicillin- sensitive S. aureus strains from Pomerania, 107 nasal and 88 blood culture isolates, were investigated. All superantigen-encoding MGEs were linked more or less tightly to the genetic background. Thus, each S. aureus clonal complex was characterized by a typical repertoire of superantigen and exfoliative toxin genes. However, within each S. aureus clonal complex and even within the same spa type, virulence gene profiles varied remarkably. Therefore, virulence genes of nasal and blood culture isolates were separately compared in each clonal complex. The results indicated a role in infection for the MGE harboring the exfoliative toxin D gene. In contrast, there was no association of superantigen genes with bloodstream invasion. In summary, we show here that the simultaneous assessment of virulence gene profiles and the genetic background increases the discriminatory power of genetic investigations into the mechanisms of S. aureus pathogenesis. [Abstract/Link to Full Text]

Schwetz I, Hinrichs G, Reisinger EC, Krejs GJ, Olschewski H, Krause R
Delayed processing of blood samples influences time to positivity of blood cultures and results of Gram stain-acridine orange leukocyte Cytospin test.
J Clin Microbiol. 2007 Aug;45(8):2691-4.
We investigated in vitro whether storage of blood samples influences the time to positivity used for the calculation of the differential time to positivity (DTP) and the results of the Gram stain-acridine orange leukocyte Cytospin (AOLC) test. A 24-hour storage of blood samples at room temperature may lead to false-negative DTP and false-positive Gram stain-AOLC test results, whereas storage at 4 degrees C does not. [Abstract/Link to Full Text]

Evander M, Eriksson I, Pettersson L, Juto P, Ahlm C, Olsson GE, Bucht G, Allard A
Puumala hantavirus viremia diagnosed by real-time reverse transcriptase PCR using samples from patients with hemorrhagic fever and renal syndrome.
J Clin Microbiol. 2007 Aug;45(8):2491-7.
Puumala virus (PUUV) is the endemic hantavirus in northern Sweden and causes nephropathia epidemica (NE), a milder form of hemorrhagic fever with renal syndrome. There is a need for fast and reliable diagnostics to differentiate the disease from other infections. By aligning virus RNA sequences isolated from 11 different bank voles and one human patient, we designed a real-time reverse transcriptase (RT) PCR method for detection of PUUV RNA. The real-time RT-PCR assay showed linearity from 20 to 2 x 10(6) virus copies with a correlation coefficient above 0.98 to 0.99 for all experiments. The detection threshold for PUUV cDNA was two copies per reaction. A two-step qualitative RT-PCR to detect PUUV RNA showed 100% concordance with the real-time RT-PCR assay. PUUV RNA viremia was detected in 33 of 34 PUUV immunoglobulin M (IgM)-positive patients with typical clinical NE disease from the region of endemicity. One PUUV IgM-negative sample had PUUV RNA, and 4 days later, the patient was IgM positive. Of samples with indeterminate IgM, 43% were PUUV RNA positive. The kinetics of antibody titers and PUUV viremia were studied, and five of six NE patients displayed a decrease in PUUV viremia a few days after disease outbreak coupled with an increase in PUUV IgM and IgG. In one patient with continuously high PUUV RNA levels but low IgM and no IgG response, the infection was lethal. These findings demonstrated that real-time RT-PCR is a useful method for diagnosis of PUUV viremia and for detecting PUUV RNA at early time points, before the appearance of IgM antibodies. [Abstract/Link to Full Text]

Chernesky M, Jang D, Portillo E, Chong S, Smieja M, Luinstra K, Petrich A, Macritchie C, Ewert R, Hayhoe B, Sarabia A, Thompson F
Abilities of APTIMA, AMPLICOR, and ProbeTec assays to detect Chlamydia trachomatis and Neisseria gonorrhoeae in PreservCyt ThinPrep Liquid-based Pap samples.
J Clin Microbiol. 2007 Aug;45(8):2355-8.
Infections with Chlamydia trachomatis and Neisseria gonorrhoeae are often asymptomatic. Liquid-based Pap (L-Pap) screening may provide samples for testing by commercial assays. Women attending a health clinic or a street youth clinic had a PreservCyt ThinPrep sample and a cervical swab (CS) collected. The L-Pap sample was tested for cytopathology; then 1 ml was transferred to an L-Pap specimen transfer tube for testing by the Gen-Probe APTIMA assays (APTIMA Combo 2 [AC2], APTIMA C. trachomatis [ACT], and APTIMA N. gonorrhoeae [AGC]). The residual L-Pap sample was tested for C. trachomatis and N. gonorrhoeae using Roche AMPLICOR (AMP) and Becton Dickinson ProbeTec (PT). The CS was tested by AC2. A patient was considered infected if two specimens were positive or if a single specimen was positive in two tests. The prevalence of infection was 10% (29/290) for C. trachomatis and 2.4% (7/290) for N. gonorrhoeae. Most of the positive patients had specimens that were reactive in all assays (20/29 for C. trachomatis; 6/7 for N. gonorrhoeae). Four patients had double infections. The sensitivities and specificities of the various tests for the specimens tested were as follows. For C. trachomatis on L-Pap, sensitivity and specificity were 100 and 98.1%, respectively, for ACT, 93.1 and 98.8% for AC2, 86.2 and 91.2% for AMP, and 72.4 and 92.7% for PT. For N. gonorrhoeae on L-Pap, sensitivity and specificity were 100% for both AGC and AC2, 85.7 and 100% for AMP, and 85.7 and 100% for PT. For AC2 with CSs, sensitivity and specificity were 93.1 and 98.5%, respectively, for C. trachomatis, and both were 100% for N. gonorrhoeae. There were significant differences in sensitivity and specificity (P < 0.001). The APTIMA assays were more sensitive and specific than AMP or PT for detecting women's C. trachomatis and/or N. gonorrhoeae infections by testing ThinPrep samples. [Abstract/Link to Full Text]

Thibault VC, Grayon M, Boschiroli ML, Hubbans C, Overduin P, Stevenson K, Gutierrez MC, Supply P, Biet F
New variable-number tandem-repeat markers for typing Mycobacterium avium subsp. paratuberculosis and M. avium strains: comparison with IS900 and IS1245 restriction fragment length polymorphism typing.
J Clin Microbiol. 2007 Aug;45(8):2404-10.
Mycobacterium avium subsp. paratuberculosis, the etiological agent of paratuberculosis, affects a wide range of domestic ruminants and has been suggested to be involved in Crohn's disease in humans. Most available methods for identifying and differentiating strains of this difficult species are technically demanding and have limited discriminatory power. Here, we report the identification of novel PCR-based typing markers consisting of variable-number tandem repeats (VNTRs) of genetic elements called mycobacterial interspersed repetitive units (MIRUs). Eight markers were applied to 183 M. avium subsp. paratuberculosis isolates from bovine, caprine, ovine, cervine, leporine, and human origins from 10 different countries and to 82 human isolates of the closely related species M. avium from France. Among the M. avium subsp. paratuberculosis isolates, 21 patterns were found by MIRU-VNTR typing, with a discriminatory index of 0.751. The predominant R01 IS900 restriction fragment length polymorphism type, comprising 131 isolates, was divided into 15 MIRU-VNTR types. Among the 82 M. avium isolates, the eight MIRU-VNTR loci distinguished 30 types, none of which was shared by M. avium subsp. paratuberculosis isolates, resulting in a discriminatory index of 0.889. Our results suggest that MIRU-VNTR typing is a fast typing method that, in combination with other methods, might prove to be optimal for PCR-based molecular epidemiological studies of M. avium/M. avium subsp. paratuberculosis pathogens. In addition, presumably identical M. avium subsp. paratuberculosis 316F vaccine strains originating from the Weybridge laboratory and from different commercial batches from Mérial actually differed by one or both typing methods. These results indicate a substantial degree of genetic drift among different vaccine preparations, which has important implications for prophylactic approaches. [Abstract/Link to Full Text]

Ticehurst JR, Hamzeh FM, Thomas DL
Factors affecting serum concentrations of hepatitis C virus (HCV) RNA in HCV genotype 1-infected patients with chronic hepatitis.
J Clin Microbiol. 2007 Aug;45(8):2426-33.
The serum concentration of hepatitis C virus (HCV) RNA is usually stable (4 to 8 log(10) IU/ml) in untreated patients with chronic hepatitis C. While this baseline HCV RNA concentration ([HCV RNA](BL)) is predictive of a sustained virologic response to treatment, its determinants are only partially identified. We therefore analyzed the baseline characteristics of 2,472 HCV genotype 1-infected patients to identify correlations with gender, age, race, weight, body mass index (BMI), HCV acquisition mode, HCV subtype, alanine aminotransferase concentration, or histopathologic changes in the liver. After separation of the data according to four [HCV RNA](BL) groups (< or =5.0, >5.0 to 5.6, >5.6 to 5.9, and >5.9 log(10) IU/ml), we determined that increasing [HCV RNA](BL) correlated (P < 0.05) with increasing proportions of patients who were male, >40 years of age, or heavier (a weight of >85 kg or a BMI of >27 kg/m(2)). Histologic activity index (HAI) data were available for 1,304 of these patients: increasing [HCV RNA](BL) correlated with higher fibrosis and necrosis-inflammation scores. As a continuous variable, [HCV RNA](BL) correlated with age, gender, weight (continuous or < or =85 versus >85 kg), BMI (continuous or < or =27 versus >27 kg/m(2)), subtype, fibrosis score, and necrosis-inflammation score; however, multiple-regression analysis yielded P values of <0.1 only for age, gender, BMI (< or =27 versus >27 kg/m(2)), and fibrosis score. While our findings are suggestive of a role for these factors in maintenance of the pretreatment state of HCV infection, the multiple-regression model accounted for only < or =4.6% of the [HCV RNA](BL) differences between individuals (R(2) = 0.046 for 1,304 patients with HAI scores; 0.043 for all 2,472 patients). [Abstract/Link to Full Text]

Nasri D, Bouslama L, Omar S, Saoudin H, Bourlet T, Aouni M, Pozzetto B, Pillet S
Typing of human enterovirus by partial sequencing of VP2.
J Clin Microbiol. 2007 Aug;45(8):2370-9.
The sequencing of the VP1 hypervariable region of the human enterovirus (HEV) genome has become the reference test for typing field isolates. This study describes a new strategy for typing HEV at the serotype level that uses a reverse transcription-PCR assay targeting the central part of the VP2 capsid protein. Two pairs of primers were used to amplify a fragment of 584 bp (with reference to the PV-1 sequence) or a part of it (368 bp) for typing. For a few strains not amplified by the first PCR, seminested primers enhanced the sensitivity (which was found to be approximately 10(-1) and 10(-4) 50% tissue culture infective dose per reaction tube for the first and seminested assay, respectively). The typing method was then applied to 116 clinical and environmental strains of HEV. Sixty-one typeable isolates were correctly identified at the serotype level by comparison to seroneutralization. Forty-eight of 55 "untypeable" strains (87.3%) exhibited the same serotype using VP1 and VP2 sequencing methods. For six strains (four identified as EV-71, one as E-9, and one as E-30 by the VP2 method), no amplification was obtained by the VP1 method. The last strain, typed as CV-B4 by VP1 and CV-B3 by VP2 and monovalent antiserum, could exhibit recombination within the capsid region. Although the VP2 method was tested on only 36 of the 68 HEV serotypes, it appears to be a promising strategy for typing HEV strains isolated on a routine basis. The good sensitivity of the seminested technique could avoid cell culture and allow HEV typing directly from PCR products. [Abstract/Link to Full Text]

Breton J, Bart-Delabesse E, Biligui S, Carbone A, Seiller X, Okome-Nkoumou M, Nzamba C, Kombila M, Accoceberry I, Thellier M
New highly divergent rRNA sequence among biodiverse genotypes of Enterocytozoon bieneusi strains isolated from humans in Gabon and Cameroon.
J Clin Microbiol. 2007 Aug;45(8):2580-9.
Intestinal microsporidiosis due to Enterocytozoon bieneusi is a leading cause of chronic diarrhea in severely immunocompromised human immunodeficiency virus (HIV)-positive patients. It may be a public health problem in Africa due to the magnitude of the HIV pandemic and to poor sanitary conditions. We designed two prevalence studies of E. bieneusi in Central Africa, the first with HIV-positive patients from an urban setting in Gabon and the second with a nonselected rural population in Cameroon. Stool samples were analyzed by an immunofluorescence antibody test and PCR. Twenty-five out of 822 HIV-positive patients from Gabon and 22 out of 758 villagers from Cameroon were found to be positive for E. bieneusi. The prevalence rates of the two studies were surprisingly similar (3.0% and 2.9%). Genotypic analysis of the internal transcribed spacer region of the rRNA gene showed a high degree of diversity in samples from both countries. In Gabon, 15 isolates showed seven different genotypes: the previously reported genotypes A, D, and K along with four new genotypes, referred to as CAF1, CAF2, CAF3, and CAF4. In Cameroon, five genotypes were found in 20 isolates: the known genotypes A, B, D, and K and the new genotype CAF4. Genotypes A and CAF4 predominated in Cameroon, whereas K, CAF4, and CAF1 were more frequent in Gabon, suggesting that different genotypes present differing risks of infection associated with immune status and living conditions. Phylogenetic analysis of the new genotype CAF4, identified in both HIV-negative and HIV-positive subjects, indicates that it represents a highly divergent strain. [Abstract/Link to Full Text]

Balajee SA, Lindsley MD, Iqbal N, Ito J, Pappas PG, Brandt ME
Nonsporulating clinical isolate identified as Petromyces alliaceus (anamorph Aspergillus alliaceus) by morphological and sequence-based methods.
J Clin Microbiol. 2007 Aug;45(8):2701-3.
Concerted morphological and sequencing-based strategies revealed the identity of a nonsporulating clinical isolate as Petromyces alliaceus (anamorph Aspergillus alliaceus). This rare Aspergillus sp. was recovered as the etiological agent of invasive pulmonary aspergillosis and had reduced in vitro susceptibilities to amphotericin B and caspofungin, which correlated with clinical failure of therapy. [Abstract/Link to Full Text]

Hillemann D, Rüsch-Gerdes S, Richter E
Evaluation of the GenoType MTBDRplus assay for rifampin and isoniazid susceptibility testing of Mycobacterium tuberculosis strains and clinical specimens.
J Clin Microbiol. 2007 Aug;45(8):2635-40.
The new GenoType MTBDRplus assay (Hain Lifescience GmbH, Nehren, Germany) was tested with 125 clinical isolates and directly with 72 smear-positive sputum specimens for its ability to detect rifampin (RMP) and isoniazid (INH) resistance in Mycobacterium tuberculosis complex (MTBC) strains. In total, 106 RMP(r)/INH(r), 10 RMP(s)/INH(r), and 80 RMP(s)/INH(s) MTBC strains were comparatively analyzed with the new and the old MTBDR assays. Besides the detection of mutations within the 81-bp hot spot region of rpoB and katG codon 315, the GenoType MTBDRplus assay is designed to detect mutations in the regulatory region of inhA. The applicability of the new assay directly to specimens was shown, since 71 of 72 results for smear-positive sputa and all 125 results for clinical isolates were interpretable and no discrepancies compared with the results of real-time PCR or DNA sequencing were obtained. In comparison to conventional drug susceptibility testing, both assays were able to identify RMP resistance correctly in 74 of 75 strains (98.7%) and 30 of 31 specimens (96.8%). The misidentification of RMP resistance was obtained for two strains containing rpoB P533L mutations. Compared to the old MTBDR assay, the new GenoType MTBDRplus assay enhanced the rate of detection of INH resistance from 66 (88.0%) to 69 (92.0%) among the 75 INH-resistant strains and 36 (87.8%) to 37 (90.2%) among the 41 specimens containing INH-resistant strains. Thus, the new GenoType MTBDRplus assay represents a reliable and upgraded tool for the detection of INH and RMP resistance in strains or directly from smear-positive specimens. [Abstract/Link to Full Text]

Carvalho Mda G, Tondella ML, McCaustland K, Weidlich L, McGee L, Mayer LW, Steigerwalt A, Whaley M, Facklam RR, Fields B, Carlone G, Ades EW, Dagan R, Sampson JS
Evaluation and improvement of real-time PCR assays targeting lytA, ply, and psaA genes for detection of pneumococcal DNA.
J Clin Microbiol. 2007 Aug;45(8):2460-6.
The accurate diagnosis of pneumococcal disease has frequently been hampered not only by the difficulties in obtaining isolates of the organism from patient specimens but also by the misidentification of pneumococcus-like viridans group streptococci (P-LVS) as Streptococcus pneumoniae. This is especially critical when the specimen comes from the respiratory tract. In this study, three novel real-time PCR assays designed for the detection of specific sequence regions of the lytA, ply, and psaA genes were developed (lytA-CDC, ply-CDC, and psaA, respectively). These assays showed high sensitivity (<10 copies for lytA-CDC and ply-CDC and an approximately twofold less sensitivity for psaA). Two additional real-time PCR assays for lytA and ply described previously for pneumococcal DNA detection were also evaluated. A panel of isolates consisting of 67 S. pneumoniae isolates (44 different serotypes and 3 nonencapsulated S. pneumoniae isolates from conjunctivitis outbreaks) and 104 nonpneumococcal isolates was used. The 67 S. pneumoniae isolates were reactive in all five assays. The new real-time detection assays targeting the lytA and psaA genes were the most specific for the detection of isolates confirmed to be S. pneumoniae, with lytA-CDC showing the greatest specificity. Both ply PCRs were positive for all isolates of S. pseudopneumoniae, along with 13 other isolates of other P-LVS isolates confirmed to be non-S. pneumoniae by DNA-DNA reassociation. Thus, the use of the ply gene for the detection of pneumococci can lead to false-positive reactions in the presence of P-LVS. The five assays were applied to 15 culture-positive cerebrospinal fluid specimens with 100% sensitivity; and serum and ear fluid specimens were also evaluated. Both the lytA-CDC and psaA assays, particularly the lytA-CDC assay, have improved specificities compared with those of currently available assays and should therefore be considered the assays of choice for the detection of pneumococcal DNA, particularly when upper respiratory P-LVS might be present in the clinical specimen. [Abstract/Link to Full Text]

Ghosh S, Varghese V, Samajdar S, Sinha M, Naik TN, Kobayashi N
Evidence for bovine origin of VP4 and VP7 genes of human group A rotavirus G6P[14] and G10P[14] strains.
J Clin Microbiol. 2007 Aug;45(8):2751-3. [Abstract/Link to Full Text]

Castor J, Cook L, Corey L, Jerome KR
Rapid detection directly from patient serum samples of human cytomegalovirus UL97 mutations conferring ganciclovir resistance.
J Clin Microbiol. 2007 Aug;45(8):2681-3.
Ganciclovir-resistant cytomegalovirus can cause disease and death in transplant recipients. We describe here a rapid PCR- and sequencing-based assay for ganciclovir resistance that can be performed in 1 to 2 working days directly from patient specimens, without the need for amplification of the virus by cell culture. An evaluation of 120 sequential samples submitted for clinical testing revealed a variety of silent and amino acid mutations. [Abstract/Link to Full Text]

Dumke R, Schurwanz N, Lenz M, Schuppler M, Lück C, Jacobs E
Sensitive detection of Mycoplasma pneumoniae in human respiratory tract samples by optimized real-time PCR approach.
J Clin Microbiol. 2007 Aug;45(8):2726-30.
To enhance the sensitivity of the available real-time PCR systems for the detection of Mycoplasma pneumoniae, we established a method to amplify copies of the repetitive element repMp1. In a study of respiratory tract samples, we found that, compared to the use of the conserved part of the P1 adhesin gene as a monocopy target, the use of the repMp1-PCR showed an increase in the detected genome equivalents by a factor of 22. [Abstract/Link to Full Text]

van Klingeren B, Dessens-Kroon M, van der Laan T, Kremer K, van Soolingen D
Drug susceptibility testing of Mycobacterium tuberculosis complex by use of a high-throughput, reproducible, absolute concentration method.
J Clin Microbiol. 2007 Aug;45(8):2662-8.
Accurate drug susceptibility testing (DST) for Mycobacterium tuberculosis is highly important for both therapy guidance and surveillance of drug resistance. Although liquid medium DST methods are used increasingly and seem most efficient and fast, the high costs hamper widespread implementation. In addition, an inability to check the colony morphology of the growing bacteria is a disadvantage of these methods. Moreover, these methods discriminate only between susceptibility and resistance and do not determine the MIC. In this paper, we describe a low-cost, reproducible, high-throughput, proportional absolute concentration DST method. The method uses a concentration series of antituberculosis drugs, including pyrazinamide in 7H10 medium, distributed semiautomatically in 25-well plates. The performance of this 25-well DST method was evaluated by the World Health Organization and the International Union against Tuberculosis and Lung Disease in 10 rounds of proficiency testing regarding sensitivity, specificity, efficiency, reproducibility, and predictive value for resistance and susceptibility. The performance of the method for these characteristics was 100% for isoniazid and from 96 to 100% for rifampin, 91 to 100% for streptomycin, and 85 to 100% for ethambutol. The method was 100% reproducible for all four drugs. The levels of drug resistance and the MIC distributions for the first-line antituberculosis drugs were determined for all 7,956 M. tuberculosis strains isolated in The Netherlands from 1998 to 2005 and amounted to 7.5% for isoniazid, 1.4% for rifampin, 8.5% for streptomycin, and 1.0% for ethambutol. Pyrazinamide testing was successful for 7,026 (88.3%) of the isolates and showed a resistance level of 0.8%. [Abstract/Link to Full Text]

Sawyer J, Mealing D, Dalley D, Davé D, Lesellier S, Palmer S, Bowen-Davies J, Crawshaw TR, Chambers MA
Development and evaluation of a test for tuberculosis in live European badgers (Meles meles) based on measurement of gamma interferon mRNA by real-time PCR.
J Clin Microbiol. 2007 Aug;45(8):2398-403.
A real-time PCR assay for the measurement of gamma interferon (IFN-gamma) mRNA in European badger (Meles meles) blood cultures was developed. The levels of IFN-gamma mRNA in blood cultures stimulated with either bovine or avian tuberculin or specific mycobacterial antigens were compared with those in a nonstimulated control blood culture as the basis for determining the tuberculosis (TB) status of live badgers. The assay was validated by testing 247 animals for which there were matching data from postmortem examination and culture of tissues. Relative changes in the levels of IFN-gamma mRNA in response to bovine tuberculin and specific antigens were found to be greater among badgers with tissues positive for TB on culture. The test was at its most accurate (87% of test results were correct) by using blood cultures containing bovine tuberculin as the antigen and when the response to avian tuberculin was taken into account by subtracting the avian tuberculin response from the bovine tuberculin response. At a specificity of 90.7%, the test was 70.6% sensitive. At the same specificity, the current serological enzyme-linked immunosorbent assay for TB in badgers was only 53% sensitive. This work demonstrates that measurement of IFN-gamma mRNA by real-time PCR is a valid method for the detection of TB in live badgers and may provide an alternative to the current serological methods of diagnosis, the Brock test. The testing procedure can be completed within 5 h of receipt of the blood culture samples. In addition, the use of a molecular biology-based test offers the potential to fully automate the testing procedure through the use of robotics. [Abstract/Link to Full Text]

Cama VA, Pearson J, Cabrera L, Pacheco L, Gilman R, Meyer S, Ortega Y, Xiao L
Transmission of Enterocytozoon bieneusi between a child and guinea pigs.
J Clin Microbiol. 2007 Aug;45(8):2708-10.
An unusual Enterocytozoon bieneusi genotype was found in seven guinea pigs and a 2-year-old child in the same household. The genetic uniqueness of the parasite, its wide occurrence in other guinea pigs in the community, and its absence in other children in the community suggest the possibility of zoonotic transmission of the infection to the study child. [Abstract/Link to Full Text]

Kindberg E, Akerlind B, Johnsen C, Knudsen JD, Heltberg O, Larson G, Böttiger B, Svensson L
Host genetic resistance to symptomatic norovirus (GGII.4) infections in Denmark.
J Clin Microbiol. 2007 Aug;45(8):2720-2.
A total of 61 individuals involved in five norovirus outbreaks in Denmark were genotyped at nucleotides 428 and 571 of the FUT2 gene, determining secretor status, i.e., the presence of ABH antigens in secretions and on mucosa. A strong correlation (P = 0.003) was found between the secretor phenotype and symptomatic disease, extending previous knowledge and confirming that nonsense mutations in the FUT2 gene provide protection against symptomatic norovirus (GGII.4) infections. [Abstract/Link to Full Text]

Lee WM, Grindle K, Pappas T, Marshall DJ, Moser MJ, Beaty EL, Shult PA, Prudent JR, Gern JE
High-throughput, sensitive, and accurate multiplex PCR-microsphere flow cytometry system for large-scale comprehensive detection of respiratory viruses.
J Clin Microbiol. 2007 Aug;45(8):2626-34.
Human respiratory viruses are a diverse group of pathogens composed of hundreds of virus strains, and this presents a major challenge for diagnostic laboratories. To efficiently detect numerous viruses in a large epidemiologic study, we developed a fast, multitarget, sensitive, and specific assay named the Respiratory MultiCode-PLx Assay (RMA). The RMA utilizes improved multiplex PCR chemistry (EraGen MultiCode-PLx technology) coupled with high-throughput microsphere flow cytometry (Luminex). Eighteen sets of virus-specific multiplex PCR primers were developed based on the conserved sequences of all available respiratory-virus sequences for eight distinct groups: human rhinovirus (HRV), respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza virus (InfV), metapneumovirus, adenovirus (Ad), coronavirus, and enterovirus. Each primer set detected 20 cDNA copies of the intended target per sample and had no reaction with 60,000 copies of human genomic DNA. The accuracy and sensitivity of the RMA for detecting respiratory viruses in human samples were tested with two sets of clinical specimens. First, 101 nasal-wash specimens that were positive for HRV, RSV, InfV, PIV, or Ad by traditional techniques were reanalyzed by RMA, and all target viruses were detected with an overall sensitivity of 94% and specificity of 99%. Second, 103 nasal-wash samples from 5-year-old children with asthma and respiratory symptoms were analyzed; RMA detected viruses in 74 specimens (71.8%) compared to only 24 (23.3%) by traditional culture and immunofluorescent-staining techniques. These results show that RMA is an accurate, sensitive, and practical test for respiratory-virus infections. [Abstract/Link to Full Text]

Counts JM, Astles JR, Tenover FC, Hindler J
Systems approach to improving antimicrobial susceptibility testing in clinical laboratories in the United States.
J Clin Microbiol. 2007 Jul;45(7):2230-4.
Laboratory practice in the preanalytical phase of antimicrobial susceptibility testing (AST) was evaluated in 102 hospital, reference, physician office-clinic, and public health laboratories in Washington state. Surveys were sent to evaluate (i) use of NCCLS/CLSI (formerly NCCLS) AST performance standards, (ii) technical competence in AST case studies, challenging knowledge of contemporary testing issues, and (iii) choice of antimicrobial agents to test for Streptococcus pneumoniae. Numerous deficiencies were identified in the survey: (i) initially only 40% of the laboratories surveyed used current NCCLS/CLSI AST performance standards, (ii) the rate of accurate responses for three different case studies ranged from 29% to 69%, and (iii) variation was noted in the choice of antimicrobials tested against invasive isolates of S. pneumoniae. These deficiencies could affect therapy and detection of antimicrobial resistance. Several educational programs were implemented to improve AST policies and practices, and a follow-up survey indicated that four intervention strategies were most effective: (i) regional technical workshops, (ii) National Laboratory Training Network teleconferences, (iii) use of the Centers for Disease Control and Prevention (CDC) CD-ROM on AST, and (iv) the CDC Multilevel Antimicrobial Susceptibility Testing Resource website. The interventions could be implemented more widely in the United States to improve AST knowledge and practices. [Abstract/Link to Full Text]

Qian Q, Eichelberger K, Kirby JE
Rapid identification of Staphylococcus aureus in blood cultures by use of the direct tube coagulase test.
J Clin Microbiol. 2007 Jul;45(7):2267-9.
Direct tube coagulase testing for identification of Staphylococcus aureus from BACTEC culture broth showed a sensitivity, a specificity, and positive and negative predicative values of 34%, 100%, 100%, and 80.2% with 2 h of incubation and 65%, 98.7, 99.7%, and 88.6% with 4 h of incubation. Anaerobic blood culture contributed significantly to the detection of S. aureus. [Abstract/Link to Full Text]

Lagacé-Wiens PR, Alfa MJ, Manickam K, Karlowsky JA
Thermostable DNase is superior to tube coagulase for direct detection of Staphylococcus aureus in positive blood cultures.
J Clin Microbiol. 2007 Oct;45(10):3478-9. [Abstract/Link to Full Text]

Zhang SX, Drews SJ, Tomassi J, Katz KC
Comparison of two versions of the IDI-MRSA assay using charcoal swabs for prospective nasal and nonnasal surveillance samples.
J Clin Microbiol. 2007 Jul;45(7):2278-80.
An updated IDI-MRSA assay version was released to address the assay's low positive predictive value (PPV). A prospective analysis of two assay versions indicated no significant improvement in the PPV. Colonization by methicillin-resistant Staphylococcus aureus in 24% of patients would not have been detected if only nasal samples had been tested, as approved, by this molecular method. [Abstract/Link to Full Text]

She RC, Billetdeaux E, Phansalkar AR, Petti CA
Limited applicability of direct fluorescent-antibody testing for Bordetella sp. and Legionella sp. specimens for the clinical microbiology laboratory.
J Clin Microbiol. 2007 Jul;45(7):2212-4.
The rapid diagnosis of infections with Bordetella and Legionella species is important for patient management. With observed increases in direct fluorescent-antibody (DFA) testing volumes, we retrospectively compared the performance characteristics of DFA testing to those of culture and PCR. For Bordetella sp., samples were classified as positive by DFA testing (184 [3%] of 6,195 samples) and culture (150 [2%] of 6,251 samples) significantly less often than by PCR (2,557 [10%] of 26,929 samples). Of 360 samples tested by both DFA and PCR methods, 81 (16 by DFA testing and 79 by PCR) were determined to be positive for Bordetella, with a sensitivity and specificity of DFA testing of 18% and 99%, respectively. Of 1,426 samples tested by both DFA and culture methods, 48 (44 by DFA testing and 15 by culture) were determined to be positive for Bordetella, with a sensitivity and specificity of DFA testing of 73% and 98%, respectively. For Legionella sp., samples were identified as positive by DFA testing (31 [0.25%] of 12,597 samples) and culture (85 [0.6%] of 13,572 samples) significantly less often than by PCR (27 [4%] of 716 samples). Of 62 samples tested by both DFA and PCR methods, none were positive for Legionella sp. by DFA testing and 3 were positive by PCR. Of 3,923 samples tested by both DFA and culture methods, 22 (3 by DFA testing and 21 by culture) were positive for Legionella sp., with a sensitivity and specificity of DFA testing of 9.5% and 100%. Overall, DFA testing for Bordetella sp. and Legionella sp. is an insensitive method, and despite its continued popularity, clinical microbiology laboratories should not offer it when more sensitive tests like PCR are available. [Abstract/Link to Full Text]

Bolmström A, Karlsson A, Engelhardt A, Ho P, Petersen PJ, Bradford PA, Jones CH
Validation and reproducibility assessment of tigecycline MIC determinations by Etest.
J Clin Microbiol. 2007 Aug;45(8):2474-9.
A multicenter study was conducted to validate Etest tigecycline compared to the Clinical Laboratory Standards Institute reference broth microdilution and agar dilution methodologies. A large collection of gram-negative (n = 266) and gram-positive (n = 162) aerobic bacteria, a collection of anaerobes (n = 385), and selected collections of nonpneumococcal streptococci (n = 369), Streptococcus pneumoniae (n = 372), and Haemophilus influenzae (n = 372) were tested. Strains with reduced susceptibility to tigecycline were used with all test methods. The Etest showed excellent inter- and intralaboratory reproducibility for all organism groups tested regardless of the test methodology. The essential agreement values with the reference method (+/-1 dilution) were >99% for the collection of gram-negative and gram-positive aerobes; >98% for the S. pneumoniae, H. influenzae, and anaerobe collections; and 100% for the group of nonpneumococcal streptococci. These results validate the performance accuracy and utility of Etest tigecycline and verify the reproducibility of this convenient predefined gradient methodology for tigecycline susceptibility determination. [Abstract/Link to Full Text]

Cordero CL, Sozhamannan S, Satchell KJ
RTX toxin actin cross-linking activity in clinical and environmental isolates of Vibrio cholerae.
J Clin Microbiol. 2007 Jul;45(7):2289-92.
Vibrio cholerae strains from diverse O-antigen groups were evaluated for RTX toxin actin cross-linking activity. This study demonstrates that the actin cross-linking domain sequence is present within rtxA in the majority of clinical and environmental isolates tested, and the RTX toxin produced by these strains catalyzes the covalent cross-linking of cellular actin. [Abstract/Link to Full Text]

Stamper PD, Cai M, Howard T, Speser S, Carroll KC
Clinical validation of the molecular BD GeneOhm StaphSR assay for direct detection of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in positive blood cultures.
J Clin Microbiol. 2007 Jul;45(7):2191-6.
The rapid detection of Staphylococcus aureus bacteremia and a swift determination of methicillin susceptibility has serious clinical implications affecting patient mortality. This study evaluated the StaphSR assay (BD GeneOhm, San Diego, CA), a real-time PCR assay, for the identification and differentiation of methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) from 300 positive blood cultures. The BD GeneOhm StaphSR assay was performed and interpreted according to the manufacturer's recommendations. Positive blood cultures (containing predominantly gram-positive cocci in clusters) were subcultured on 5% sheep blood agar plates. After 18 to 24 h of incubation, isolates morphologically consistent with S. aureus were presumptively identified by latex agglutination (Staphaurex Plus; Remel, Lenexa, KS). Susceptibility testing was initially performed with the Phoenix automated microbiology system (BD Diagnostics, Sparks, MD). Additional susceptibility testing of samples with discrepant results was done using BBL oxacillin screen agar (BD Diagnostics, Sparks, MD), oxacillin and cefoxitin Etests (AB Biodisk, Solna, Sweden) on Mueller-Hinton agar, an immunoassay for penicillin binding protein 2' (Denka Seiken Co., Tokyo, Japan), and mecA PCR. The sensitivity, specificity, and positive and negative predictive values of the BD GeneOhm StaphSR assay for MSSA detection were 98.9, 96.7, 93.6, and 99.5%, respectively. For the detection of MRSA, the BD GeneOhm StaphSR assay was 100% sensitive and 98.4% specific; positive and negative predictive values for MRSA detection were 92.6 and 100%, respectively. Inhibition was seen with only one sample, and the issue was resolved upon retesting. The BD GeneOhm StaphSR assay appears to be a valuable diagnostic tool for quickly differentiating bacteremia caused by MSSA and MRSA from that caused by other gram-positive cocci. [Abstract/Link to Full Text]

Mayor L, Ortellado J, Menacho C, Lird G, Courtier C, Gardon C, Meugnier H, Bes M, Vandenesch F, Etienne J
Molecular characterization of methicillin-resistant Staphylococcus aureus isolates collected in Asunción, Paraguay.
J Clin Microbiol. 2007 Jul;45(7):2298-300.
We characterized 34 methicillin-resistant Staphylococcus aureus strains isolated in Paraguay in 2005. The strains belonged to two clones. The major clone (sequence type 5 [ST5] or ST221, spa type t149, staphylococcal cassette chromosome mec [SCCmec] type I) was similar to the Cordobes/Chilean clone spreading through South America, and the minor clone (ST239 or ST889, spa type t037, SCCmec type IIIA) was related to the Brazilian clone. [Abstract/Link to Full Text]

Gomez-Gonzalez C, Alba C, Otero JR, Sanz F, Chaves F
Long persistence of methicillin-susceptible strains of Staphylococcus aureus causing sepsis in a neonatal intensive care unit.
J Clin Microbiol. 2007 Jul;45(7):2301-4.
Molecular epidemiology of Staphylococcus aureus strains causing bacteremia in neonates during 2002 to 2005 revealed seven clones, with four MSSA clones responsible for 80% of the cases. Some clones persisted or reappeared throughout the study. Three bacteremic clones were found colonizing health care workers (HCWs), particularly clone C, which was harbored by at least 15% of HCWs. [Abstract/Link to Full Text]

Thilesen CM, Nicolaidis M, Lökebö JE, Falsen E, Jorde AT, Müller F
Leptotrichia amnionii, an emerging pathogen of the female urogenital tract.
J Clin Microbiol. 2007 Jul;45(7):2344-7.
Leptotrichia amnionii, a recently described, very fastidious, gram-negative anaerobic bacterium, is an opportunistic pathogen of the female urogenital tract. We report a case of second-trimester abortion in a patient with chorioamnionitis and L. amnionii bacteremia and a case of renal abscess in a female 5 weeks postpartum. [Abstract/Link to Full Text]

Louisirirotchanakul S, Lerdsamran H, Wiriyarat W, Sangsiriwut K, Chaichoune K, Pooruk P, Songserm T, Kitphati R, Sawanpanyalert P, Komoltri C, Auewarakul P, Puthavathana P
Erythrocyte binding preference of avian influenza H5N1 viruses.
J Clin Microbiol. 2007 Jul;45(7):2284-6.
Five erythrocyte species (horse, goose, chicken, guinea pig, and human) were used to agglutinate avian influenza H5N1 viruses by hemagglutination assay and to detect specific antibody by hemagglutination inhibition test. We found that goose erythrocytes confer a greater advantage over other erythrocyte species in both assays. [Abstract/Link to Full Text]

Cooke FJ, Wain J, Fookes M, Ivens A, Thomson N, Brown DJ, Threlfall EJ, Gunn G, Foster G, Dougan G
Prophage sequences defining hot spots of genome variation in Salmonella enterica serovar Typhimurium can be used to discriminate between field isolates.
J Clin Microbiol. 2007 Aug;45(8):2590-8.
Sixty-one Salmonella enterica serovar Typhimurium isolates of animal and human origin, matched by phage type, antimicrobial resistance pattern, and place of isolation, were analyzed by microbiological and molecular techniques, including pulsed-field gel electrophoresis (PFGE) and plasmid profiling. PFGE identified 10 profiles that clustered by phage type and antibiotic resistance pattern with human and animal isolates distributed among different PFGE profiles. Genomic DNA was purified from 23 representative strains and hybridized to the composite Salmonella DNA microarray, and specific genomic regions that exhibited significant variation between isolates were identified. Bioinformatic analysis showed that variable regions of DNA were associated with prophage-like elements. Subsequently, simple multiplex PCR assays were designed on the basis of these variable regions that could be used to discriminate between S. enterica serovar Typhimurium isolates from the same geographical region. These multiplex PCR assays, based on prophage-like elements and Salmonella genomic island 1, provide a simple method for identifying new variants of S. enterica serovar Typhimurium in the field. [Abstract/Link to Full Text]

Al-Benwan K, Abbott S, Janda JM, Huys G, Albert MJ
Cystitis caused by Aeromonas caviae.
J Clin Microbiol. 2007 Jul;45(7):2348-50.
Aeromonas sp. organisms rarely cause urinary tract infection. We report for the first time a case of urinary tract infection caused by A. caviae in an adult patient with a history of increased frequency of urination, dysuria, hematuria, and weight loss. [Abstract/Link to Full Text]

Klungthong C, Gibbons RV, Thaisomboonsuk B, Nisalak A, Kalayanarooj S, Thirawuth V, Nutkumhang N, Mammen MP, Jarman RG
Dengue virus detection using whole blood for reverse transcriptase PCR and virus isolation.
J Clin Microbiol. 2007 Aug;45(8):2480-5.
Dengue is one of the most important diseases in the tropical and subtropical regions of the world, with an estimated 2.5 billion people being at risk. Detection of dengue virus infections has great importance for the clinical management of patients, surveillance, and clinical trial assessments. Traditionally, blood samples are collected in serum separator tubes, processed for serum, and then taken to the laboratory for analysis. The use of whole blood has the potential advantages of requiring less blood, providing quicker results, and perhaps providing better sensitivity during the acute phase of the disease. We compared the results obtained by reverse transcriptase PCR (RT-PCR) with blood drawn into tubes containing EDTA and those obtained by RT-PCR with blood samples in serum separator tubes from 108 individuals clinically suspected of being infected with dengue virus. We determined that the extraction of RNA from whole blood followed by RT-PCR resulted in a higher detection rate than the use of serum or plasma. Using a selection of these samples, we also found that our ability to detect virus by direct C6/36 cell culture and mosquito inoculation was enhanced by using whole blood but not to the same extent as that seen by the use of RT-PCR. [Abstract/Link to Full Text]

Pham NT, Khamrin P, Nguyen TA, Kanti DS, Phan TG, Okitsu S, Ushijima H
Isolation and molecular characterization of Aichi viruses from fecal specimens collected in Japan, Bangladesh, Thailand, and Vietnam.
J Clin Microbiol. 2007 Jul;45(7):2287-8.
Aichi virus is a new member of the family Picornaviridae, genus Kobuvirus, and is associated with human gastroenteritis. This study detected Aichi virus in 28 of 912 fecal specimens which were negative for rotavirus, adenovirus, norovirus, sapovirus, and astrovirus and were collected in Japan, Bangladesh, Thailand, and Vietnam during 2002 to 2005. [Abstract/Link to Full Text]

Maaroufi Y, De Bruyne JM, Heymans C, Crokaert F
Real-time PCR for determining capsular serotypes of Haemophilus influenzae.
J Clin Microbiol. 2007 Jul;45(7):2305-8.
A two-step real-time PCR assay targeting all six capsulation loci of Haemophilus influenzae (i.e., serotypes a to f) was developed and compared with a previously published qualitative PCR assay by using 131 H. influenzae clinical isolates. There was a 98.5% concordance between the two tests. The sensitivity of detection of capsular type-specific reference strains of H. influenzae a to c (10(1) CFU/PCR) was higher than that for type e (10(3) CFU/PCR) and types d and f (10(4) CFU/PCR), and a broader dynamic range was obtained (5 to 8 log(10) units). No cross-reaction was observed with bacteria commonly isolated from the respiratory tract. We showed that both PCR assays are more reliable than slide agglutination serotyping. The real-time PCR-based assay seems to be an alternative of choice for the epidemiological follow-up of H. influenzae invasive infections. [Abstract/Link to Full Text]

Taylor NS, Xu S, Nambiar P, Dewhirst FE, Fox JG
Enterohepatic Helicobacter species are prevalent in mice from commercial and academic institutions in Asia, Europe, and North America.
J Clin Microbiol. 2007 Jul;45(7):2166-72.
The discovery of Helicobacter hepaticus and its role in hepatitis, hepatocellular carcinoma, typhlocolitis, and lower-bowel carcinoma in murine colonies was followed by the isolation and characterization of other Helicobacter spp. involved in enterohepatic disease. Colonization of mouse colonies with members of the family Helicobacteriaceae has become an increasing concern for the research community. From 2001 to 2005, shipments of selected gift mice from other institutions and mice received from specified commercial vendors were screened for Helicobacter spp. by culture of cecal tissue. The identities of the isolates were confirmed by genus-specific PCR, followed by species-specific PCR and restriction fragment length polymorphism analysis. Sequencing of the 16S rRNA gene was performed if the species identity was not apparent. The survey included 79 mice from 34 sources: 2 commercial sources and 16 research sources from the United States and 1 commercial source and 15 research sources from Canada, Europe, or Asia. Helicobacter spp. were cultured from the ceca of 62 of 79 mice. No Helicobacter spp. were found in mice from advertised Helicobacter-free production areas from two U.S. vendors. Multiple Helicobacter spp. were found in mice from one vendor's acknowledged Helicobacter-infected production area. The European commercial vendor had mice infected with novel Helicobacter sp. strain MIT 96-1001. Of the U.S. academic institutions, 6 of 16 (37%) had mice infected with Helicobacter hepaticus; but monoinfection with H. bilis, H. mastomyrinus, H. rodentium, and MIT 96-1001 was also encountered, as were mice infected simultaneously with two Helicobacter spp. Non-U.S. academic institutions had mice that were either monoinfected with H. hepaticus, monoinfected with seven other Helicobacter spp., or infected with a combination of Helicobacter spp. This survey indicates that 30 of 34 (88%) commercial and academic institutions in Canada, Europe, Asia, Australia, and the United States have mouse colonies infected with Helicobacter spp. Mice from 20 of the 34 institutions (59%) were most commonly colonized with H. hepaticus alone or in combination with other Helicobacter spp. These results indicate that a broad range of Helicobacter spp. infect mouse research colonies. The potential impact of these organisms on in vivo experiments continues to be an important issue for mice being used for biomedical research. [Abstract/Link to Full Text]

O'Donnell K, Sarver BA, Brandt M, Chang DC, Noble-Wang J, Park BJ, Sutton DA, Benjamin L, Lindsley M, Padhye A, Geiser DM, Ward TJ
Phylogenetic diversity and microsphere array-based genotyping of human pathogenic Fusaria, including isolates from the multistate contact lens-associated U.S. keratitis outbreaks of 2005 and 2006.
J Clin Microbiol. 2007 Jul;45(7):2235-48.
In 2005 and 2006, outbreaks of Fusarium keratitis associated with soft contact lens use occurred in multiple U.S. states and Puerto Rico. A case-control study conducted by the Centers for Disease Control and Prevention (CDC) showed a significant association between infections and the use of one particular brand of lens solution. To characterize the full spectrum of the causal agents involved and their potential sources, partial DNA sequences from three loci (RPB2, EF-1alpha, and nuclear ribosomal rRNA) totaling 3.48 kb were obtained from 91 corneal and 100 isolates from the patient's environment (e.g., contact lens and lens cases). We also sequenced a 1.8-kb region encoding the RNA polymerase II second largest subunit (RPB2) from 126 additional pathogenic isolates to better understand how the keratitis outbreak isolates fit within the full phylogenetic spectrum of clinically important fusaria. These analyses resulted in the most robust phylogenetic framework for Fusarium to date. In addition, RPB2 nucleotide variation within a 72-isolate panel was used to design 34 allele-specific probes to identify representatives of all medically important species complexes and 10 of the most important human pathogenic Fusarium in a single-well diagnostic assay, using flow cytometry and fluorescent microsphere technology. The multilocus data revealed that one haplotype from each of the three most common species comprised 55% of CDC's corneal and environmental isolates and that the corneal isolates comprised 29 haplotypes distributed among 16 species. The high degree of phylogenetic diversity represented among the corneal isolates is consistent with multiple sources of contamination. [Abstract/Link to Full Text]


Recent Articles in Journal of Immune Based Therapies and Vaccines

No recent articles are currently available.

Recent Articles in Journal of Virology

Buser C, Walther P, Mertens T, Michel D
Cytomegalovirus primary envelopment occurs at large infoldings of the inner nuclear membrane.
J Virol. 2007 Mar;81(6):3042-8.
We have investigated the morphogenesis of human and murine cytomegalovirus by transmission electron microscopy after high-pressure freezing, freeze substitution, and plastic embedding. We observed large tubular infoldings of the inner nuclear membrane that were free of lamina and active in primary envelopment and subsequent transport of capsids to the nuclear periphery. Semiquantitative determinations of the enlarged inner nuclear membrane area and the location of the primary envelopment of nucleocapsids demonstrated that this structure represents a virus-induced specialized membrane domain at which the particles are preferentially enveloped. This is a previously undescribed structural element relevant in cytomegalovirus morphogenesis. [Abstract/Link to Full Text]

Manrique A, Rusert P, Joos B, Fischer M, Kuster H, Leemann C, Niederöst B, Weber R, Stiegler G, Katinger H, Günthard HF, Trkola A
In vivo and in vitro escape from neutralizing antibodies 2G12, 2F5, and 4E10.
J Virol. 2007 Aug;81(16):8793-808.
Recently, passive immunization of human immunodeficiency virus (HIV)-infected individuals with monoclonal antibodies (MAbs) 2G12, 2F5, and 4E10 provided evidence of the in vivo activity of 2G12 but raised concerns about the function of the two membrane-proximal external region (MPER)-specific MAbs (A. Trkola, H. Kuster, P. Rusert, B. Joos, M. Fischer, C. Leemann, A. Manrique, M. Huber, M. Rehr, A. Oxenius, R. Weber, G. Stiegler, B. Vcelar, H. Katinger, L. Aceto, and H. F. Gunthard, Nat. Med. 11:615-622, 2005). In the light of MPER-targeting vaccines under development, we performed an in-depth analysis of the emergence of mutations conferring resistance to these three MAbs to further elucidate their activity. Clonal analysis of the MPER of plasma virus samples derived during antibody treatment confirmed that no changes in this region had occurred in vivo. Sequence analysis of the 2G12 epitope relevant N-glycosylation sites of viruses derived from 13 patients during the trial supported the phenotypic evaluation, demonstrating that mutations in these sites are associated with resistance. In vitro selection experiments with isolates of four of these individuals corroborated the in vivo finding that virus strains rapidly escape 2G12 pressure. Notably, in vitro resistance mutations differed, in most cases, from those found in vivo. Importantly, in vitro selection with 2F5 and 4E10 demonstrated that resistance to these MAbs can be difficult to achieve and can lead to selection of variants with impaired infectivity. This remarkable vulnerability of the virus to interference within the MPER calls for a further evaluation of the safety and efficacy of MPER-targeting therapeutic and vaccination strategies. [Abstract/Link to Full Text]

Chen Y, Livingston CM, Carrington-Lawrence SD, Bai P, Weller SK
A mutation in the human herpes simplex virus type 1 UL52 zinc finger motif results in defective primase activity but can recruit viral polymerase and support viral replication efficiently.
J Virol. 2007 Aug;81(16):8742-51.
Herpes simplex virus type 1 (HSV-1) encodes a heterotrimeric helicase/primase complex consisting of UL5, UL8, and UL52. UL5 contains conserved helicase motifs, while UL52 contains conserved primase motifs, including a zinc finger motif. Although HSV-1 and HSV-2 UL52s contain a leucine residue at position 986, most other herpesvirus primase homologues contain a phenylalanine at this position. We constructed an HSV-1 UL52 L986F mutation and found that it can complement a UL52 null virus more efficiently than the wild type (WT). We thus predicted that the UL5/8/52 complex containing the L986F mutation might possess increased primase activity; however, it exhibited only 25% of the WT level of primase activity. Interestingly, the mutant complex displayed elevated levels of DNA binding and single-stranded DNA-dependent ATPase and helicase activities. This result confirms a complex interdependence between the helicase and primase subunits. We previously showed that primase-defective mutants failed to recruit the polymerase catalytic subunit UL30 to prereplicative sites, suggesting that an active primase, or primer synthesis, is required for polymerase recruitment. Although L986F exhibits decreased primase activity, it can support efficient replication and recruit UL30 efficiently to replication compartments, indicating that a partially active primase is capable of recruiting polymerase. Extraction with detergents prior to fixation can extract nucleosolic proteins but not proteins bound to chromatin or the nuclear matrix. We showed that UL30 was extracted from replication compartments while UL42 remained bound, suggesting that UL30 may be tethered to the replication fork by protein-protein interactions. [Abstract/Link to Full Text]

Santra S, Sun Y, Parvani JG, Philippon V, Wyand MS, Manson K, Gomez-Yafal A, Mazzara G, Panicali D, Markham PD, Montefiori DC, Letvin NL
Heterologous prime/boost immunization of rhesus monkeys by using diverse poxvirus vectors.
J Virol. 2007 Aug;81(16):8563-70.
As the diversity of potential immunogens increases within certain classes of vectors, the possibility has arisen of employing heterologous prime/boost immunizations using diverse members of the same family of vectors. The present study was initiated to explore the use of divergent pox vectors in a prime/boost regimen to elicit high-frequency cellular immune responses to human immunodeficiency virus type 1 envelope and simian immunodeficiency virus gag in rhesus monkeys. We demonstrated that monkeys vaccinated with a recombinant modified vaccinia virus Ankara (rMVA) prime/recombinant fowlpox virus (rFPV) boost regimen and monkeys vaccinated with a recombinant vaccinia virus prime/rFPV boost regimen developed comparable cellular immune responses that were greater in magnitude than those elicited by a homologous prime/boost with rMVA. Nevertheless, comparable magnitude recall cellular immune responses were observed in monkeys vaccinated with heterologous and homologous recombinant poxvirus following challenge with the CXCR4-tropic SHIV-89.6P. Consistent with this finding, comparable levels of containment of viral replication and CD4(+) T-lymphocyte preservation were seen in these groups of recombinant poxvirus-vaccinated monkeys. This study supports further exploration of combining recombinant vectors of the same family in prime/boost immunization strategies to optimize vaccine-elicited cellular immune responses. [Abstract/Link to Full Text]

Chang SL, Beltran JA, Swarup S
Expression of the mu opioid receptor in the human immunodeficiency virus type 1 transgenic rat model.
J Virol. 2007 Aug;81(16):8406-11.
Opioids, via the mu opioid receptor (MOR), can exacerbate bacterial infections and the immunopathogenesis of human immunodeficiency virus type 1 (HIV-1) infection. Recently, an HIV-1 transgenic (HIV-1Tg) rat model containing circulating HIV-1 gp120 was created. Using real-time reverse transcription-PCR, we found that MOR mRNA levels were significantly higher in the peritoneal macrophages of the HIV-1Tg rat than those in control animals. Lipopolysaccharide, a bacterial endotoxin, induced secretion of the inflammatory cytokines tumor necrosis factor alpha (TNF-alpha), interleukin-beta (IL-beta), and IL-10 in the HIV-1Tg rat and further increased MOR expression. Ex vivo studies showed that MOR expression was up-regulated in the peritoneal macrophages of F344 control rats by exposure to serum from HIV-1Tg rats and that MOR up-regulation was abolished by addition of gp120 antibody to the serum. In human TPA-differentiated HL-60 cells, which are macrophage-like cells, LPS-induced MOR mRNA up-regulation was greater in gp120-pretreated cells than in vehicle-pretreated cells. Our data suggest that in individuals infected with HIV-1, the MOR is up-regulated, possibly by circulating HIV-1 proteins such as gp120, and HIV-1 proteins may play a significant role in modulating the response to bacterial infection in opioid-using HIV-infected individuals. Furthermore, our results demonstrate that the new HIV-1Tg rat model can be a valuable tool with which to study MOR gene expression and its effects in the continuous presence of HIV viral proteins. [Abstract/Link to Full Text]

Breakwell L, Dosenovic P, Karlsson Hedestam GB, D'Amato M, Liljeström P, Fazakerley J, McInerney GM
Semliki Forest virus nonstructural protein 2 is involved in suppression of the type I interferon response.
J Virol. 2007 Aug;81(16):8677-84.
The type I interferons (IFNs) are potent mediators of antiviral immunity, and many viruses have developed means to block their expression or their effects. Semliki Forest virus (SFV) infection induces rapid and profound silencing of host cell gene expression, a process believed to be important for the inhibition of the IFN response. In SFV-infected cells, a large proportion of the nonstructural protein nsp2 is found in the nucleus, but a role for this localization has not been described. In this work we demonstrate that a viral mutant, SFV4-RDR, in which the nuclear localization sequence of nsp2 has been rendered inactive, induces a significantly more robust IFN response in infected cells. This mutant virus replicates at a rate similar to that of the parental SFV4 strain and also shuts off host cell gene expression to similar levels, indicating that the general cellular shutoff is not responsible for the inhibition of IFN expression. Further, the rate of virus-induced nuclear translocation of early IFN transcription factors was not found to differ between the wild-type and mutant viruses, indicating that the effect of nsp2 is at a later stage. These results provide novel information about the mode of action of this viral IFN antagonist. [Abstract/Link to Full Text]

Brainard DM, Tager AM, Misdraji J, Frahm N, Lichterfeld M, Draenert R, Brander C, Walker BD, Luster AD
Decreased CXCR3+ CD8 T cells in advanced human immunodeficiency virus infection suggest that a homing defect contributes to cytotoxic T-lymphocyte dysfunction.
J Virol. 2007 Aug;81(16):8439-50.
To exert their cytotoxic function, cytotoxic T-lymphocytes (CTL) must be recruited into infected lymphoid tissue where the majority of human immunodeficiency virus (HIV) replication occurs. Normally, effector T cells exit lymph nodes (LNs) and home to peripheral sites of infection. How HIV-specific CTL migrate into lymphoid tissue from which they are normally excluded is unknown. We investigated which chemokines and receptors mediate this reverse homing and whether impairment of this homing could contribute to CTL dysfunction as HIV infection progresses. Analysis of CTL chemokine receptor expression in the blood and LNs of untreated HIV-infected individuals with stable, chronic infection or advanced disease demonstrated that LNs were enriched for CXCR3(+) CD8 T cells in all subjects, suggesting a key role for this receptor in CTL homing to infected lymphoid tissue. Compared to subjects with chronic infection, however, subjects with advanced disease had fewer CXCR3(+) CD8 T cells in blood and LNs. CXCR3 expression on bulk and HIV-specific CD8 T cells correlated positively with CD4 count and negatively with viral load. In advanced infection, there was an accumulation of HIV-specific CD8 T cells at the effector memory stage; however, decreased numbers of CXCR3(+) CD8 T cells were seen across all maturation subsets. Plasma CXCL9 and CXCL10 were elevated in both infected groups in comparison to the levels in uninfected controls, whereas lower mRNA levels of CXCR3 ligands and CD8 in LNs were seen in advanced infection. These data suggest that both CXCR3(+) CD8 T cells and LN CXCR3 ligands decrease as HIV infection progresses, resulting in reduced homing of CTL into LNs and contributing to immune dysfunction. [Abstract/Link to Full Text]

Volmer R, Prat CM, Le Masson G, Garenne A, Gonzalez-Dunia D
Borna disease virus infection impairs synaptic plasticity.
J Virol. 2007 Aug;81(16):8833-7.
The mechanisms whereby Borna disease virus (BDV) can impair neuronal function and lead to neurobehavioral disease are not well understood. To analyze the electrophysiological properties of neurons infected with BDV, we used cultures of neurons grown on multielectrode arrays, allowing a real-time monitoring of the electrical activity across the network shaped by synaptic transmission. Although infection did not affect spontaneous neuronal activity, it selectively blocked activity-dependent enhancement of neuronal network activity, one form of synaptic plasticity thought to be important for learning and memory. These findings highlight the original mechanism of the neuronal dysfunction caused by noncytolytic infection with BDV. [Abstract/Link to Full Text]

Uchiyama A, Chen M, Fane BA
Characterization and function of putative substrate specificity domain in microvirus external scaffolding proteins.
J Virol. 2007 Aug;81(16):8587-92.
Microviruses (canonical members are bacteriophages phiX174, G4, and alpha3) are T=1 icosahedral virions with an assembly pathway mediated by two scaffolding proteins. The external scaffolding protein D plays a major role during morphogenesis, particularly in icosahedral shell formation. The results of previous studies, conducted with a cloned chimeric external scaffolding gene, suggest that the first alpha-helix acts as a substrate specificity domain, perhaps mediating the initial coat-external scaffolding protein interaction. However, the expression of a cloned gene could lead to protein concentrations higher than those found in typical infections. Moreover, its induction before infection could alter the timing of the protein's accumulation. Both of these factors could drive or facilitate reactions that may not occur under physiological conditions or before programmed cell lysis. In order to elucidate a more detailed mechanistic model, a chimeric external scaffolding gene was placed directly in the phiX174 genome under wild-type transcriptional and translational control, and the chimeric virus, which was not viable on the level of plaque formation, was characterized. The results of the genetic and biochemical analyses indicate that alpha-helix 1 most likely mediates the nucleation reaction for the formation of the first assembly intermediate containing the external scaffolding protein. Mutants that can more efficiently use the chimeric scaffolding protein were isolated. These second-site mutations appear to act on a kinetic level, shortening the lag phase before virion production, perhaps lowering the critical concentration of the chimeric protein required for a nucleation reaction. [Abstract/Link to Full Text]

Vigerust DJ, Ulett KB, Boyd KL, Madsen J, Hawgood S, McCullers JA
N-linked glycosylation attenuates H3N2 influenza viruses.
J Virol. 2007 Aug;81(16):8593-600.
Over the last four decades, H3N2 subtype influenza A viruses have gradually acquired additional potential sites for glycosylation within the globular head of the hemagglutinin (HA) protein. Here, we have examined the biological effect of additional glycosylation on the virulence of H3N2 influenza viruses. We created otherwise isogenic reassortant viruses by site-directed mutagenesis that contain additional potential sites for glycosylation and examined the effect on virulence in naïve BALB/c, C57BL/6, and surfactant protein D (SP-D)-deficient mice. The introduction of additional sites was consistent with the sequence of acquisition in the globular head over the past 40 years, beginning with two sites in 1968 to the seven sites found in contemporary influenza viruses circulating in 2000. Decreased morbidity and mortality, as well as lower viral lung titers, were seen in mice as the level of potential glycosylation of the viruses increased. This correlated with decreased evidence of virus-mediated lung damage and increased in vitro inhibition of hemagglutination by SP-D. SP-D-deficient animals displayed an inverse pattern of disease, such that more highly glycosylated viruses elicited disease equivalent to or exceeding that of the wild type. We conclude from these data that increased glycosylation of influenza viruses results in decreased virulence, which is at least partly mediated by SP-D-induced clearance from the lung. The continued exploration of interactions between highly glycosylated viruses and surfactant proteins may lead to an improved understanding of the biology within the lung and strategies for viral control. [Abstract/Link to Full Text]

Pueschel K, Tietz A, Carsillo M, Steward M, Niewiesk S
Measles virus-specific CD4 T-cell activity does not correlate with protection against lung infection or viral clearance.
J Virol. 2007 Aug;81(16):8571-8.
Acute measles in children can be prevented by immunization with the live attenuated measles vaccine virus. Although immunization is able to induce CD4 and CD8 T cells as well as neutralizing antibodies, only the latter have been correlated with protective immunity. CD8 T cells, however, have been documented to be important in viral clearance in the respiratory tract, whereas CD4 T cells have been shown to be protective in a mouse encephalitis model. In order to investigate the CD4 T-cell response in infection of the respiratory tract, we have defined a T-cell epitope in the hemagglutinin (H) protein for immunization and developed a monoclonal antibody for depletion of CD4 T cells in the cotton rat model. Although the kinetics of CD4 T-cell development correlated with clearance of virus, the depletion of CD4 T cells during the primary infection did not influence viral titers in lung tissue. Immunization with the H epitope induced a CD4 T-cell response but did not protect against infection. Immunization in the presence of maternal antibodies resulted in the development of a CD4 T-cell response which (in the absence of neutralizing antibodies) did not protect against infection. In summary, CD4 T cells do not seem to protect against infection after immunization and do not participate in clearance of virus infection from lung tissue during measles virus infection. We speculate that the major role of CD4 T cells is to control and clear virus infection from other affected organs like the brain. [Abstract/Link to Full Text]

Lee JK, Prussia A, Snyder JP, Plemper RK
Reversible inhibition of the fusion activity of measles virus F protein by an engineered intersubunit disulfide bridge.
J Virol. 2007 Aug;81(16):8821-6.
In search of target sites for the development of paramyxovirus inhibitors, we have engineered disulfide bridges to introduce covalent links into the prefusion F protein trimer of measles virus. F-Edm-452C/460C, predicted to bridge head and stalk domains of different F monomers, shows a high degree of proteolytic maturation and surface expression, predominantly as stable, dithiothreitol-sensitive trimers, but no fusion activity. Reduction of disulfide bridges partially restores activity. These findings underscore the importance of reversible intersubunit interactions between the stalk and head domains for F activity. Noncovalent small molecules mimicking this behavior may constitute a potent strategy for preventing paramyxovirus entry. [Abstract/Link to Full Text]

Moriyama T, Marquez JP, Wakatsuki T, Sorokin A
Caveolar endocytosis is critical for BK virus infection of human renal proximal tubular epithelial cells.
J Virol. 2007 Aug;81(16):8552-62.
In recent years, BK virus (BKV) nephritis after renal transplantation has become a severe problem. The exact mechanisms of BKV cell entry and subsequent intracellular trafficking remain unknown. Since human renal proximal tubular epithelial cells (HRPTEC) represent a main natural target of BKV nephritis, analysis of BKV infection of HRPTEC is necessary to obtain additional insights into BKV biology and to develop novel strategies for the treatment of BKV nephritis. We coincubated HRPTEC with BKV and the cholesterol-depleting agents methyl beta cyclodextrin (MBCD) and nystatin (Nys), drugs inhibiting caveolar endocytosis. The percentage of infected cells (detected by immunofluorescence) and the cellular levels of BKV large T antigen expression (detected by Western blot analysis) were significantly decreased in both MBCD- and Nys-treated HPRTEC compared to the level in HRPTEC incubated with BKV alone. HRPTEC infection by BKV was also tested after small interfering RNA (siRNA)-dependent depletion of either the caveolar structural protein caveolin-1 (Cav-1) or clathrin, the major structural protein of clathrin-coated pits. BKV infection was inhibited in HRPTEC transfected with Cav-1 siRNA but not in HRPTEC transfected with clathrin siRNA. The colocalization of labeled BKV particles with either Cav-1 or clathrin was investigated by using fluorescent microscopy and image cross-correlation spectroscopy. The rate of colocalization of BKV with Cav-1 peaked at 4 h after incubation. Colocalization with clathrin was insignificant at all time points. These results suggest that BKV entered into HRPTEC via caveolae, not clathrin-coated pits, and that BKV is maximally associated with caveolae at 4 h after infection, prior to relocation to a different intracellular compartment. [Abstract/Link to Full Text]

Abecasis AB, Lemey P, Vidal N, de Oliveira T, Peeters M, Camacho R, Shapiro B, Rambaut A, Vandamme AM
Recombination confounds the early evolutionary history of human immunodeficiency virus type 1: subtype G is a circulating recombinant form.
J Virol. 2007 Aug;81(16):8543-51.
Human immunodeficiency virus type 1 (HIV-1) is classified in nine subtypes (A to D, F, G, H, J, and K), a number of subsubtypes, and several circulating recombinant forms (CRFs). Due to the high level of genetic diversity within HIV-1 and to its worldwide distribution, this classification system is widely used in fields as diverse as vaccine development, evolution, epidemiology, viral fitness, and drug resistance. Here, we demonstrate how the high recombination rates of HIV-1 may confound the study of its evolutionary history and classification. Our data show that subtype G, currently classified as a pure subtype, has in fact a recombinant history, having evolved following recombination between subtypes A and J and a putative subtype G parent. In addition, we find no evidence for recombination within one of the lineages currently classified as a CRF, CRF02_AG. Our analysis indicates that CRF02_AG was the parent of the recombinant subtype G, rather than the two having the opposite evolutionary relationship, as is currently proposed. Our results imply that the current classification of HIV-1 subtypes and CRFs is an artifact of sampling history, rather than reflecting the evolutionary history of the virus. We suggest a reanalysis of all pure subtypes and CRFs in order to better understand how high rates of recombination have influenced HIV-1 evolutionary history. [Abstract/Link to Full Text]

Kannanganat S, Ibegbu C, Chennareddi L, Robinson HL, Amara RR
Multiple-cytokine-producing antiviral CD4 T cells are functionally superior to single-cytokine-producing cells.
J Virol. 2007 Aug;81(16):8468-76.
Virus-specific CD4 T cells are endowed with multiple functions, such as cytokine production, CD40 ligand (CD40L) expression (associated with the costimulation of CD8 and B cells), and degranulation (associated with cytotoxic potential). Here, we used antiviral CD4 T cells present in human blood to evaluate the relationship between cytokine production and other functions of CD4 T cells. Antiviral CD4 T cells specific for a virus causing persistent infection, cytomegalovirus (CMV), and two viruses causing nonpersistent infections, influenza virus and the smallpox vaccine virus (vaccinia virus), were studied. CD4 T cells specific for each of the viruses produced all seven possible combinations of the cytokines gamma interferon (IFN-gamma), interleukin-2, and tumor necrosis factor alpha. Cells producing three or two cytokines (triple producers and double producers) represented nearly 50% of the total response to each of the viruses. Triple producers expressed the highest levels of cytokines per cell, and single producers expressed the lowest. Following stimulation, higher frequencies of triple producers than single producers expressed CD40L. Only CMV-specific CD4 T cells underwent degranulation. However, higher frequencies of CMV-specific triple producers than single producers showed this functional characteristic. In contrast to the functional phenotypes, the memory phenotypes of triple producers and IFN-gamma single producers did not differ. These results demonstrate a strong positive association between the cytokine coproduction capacity of a virus-specific CD4 T cell and its other functional characteristics and suggest that vaccines should aim to elicit T cells that coproduce more than one cytokine. [Abstract/Link to Full Text]

Townsley AC, Moss B
Two distinct low-pH steps promote entry of vaccinia virus.
J Virol. 2007 Aug;81(16):8613-20.
Entry of vaccinia virus into cells occurs by an endosomal route as well as through the plasma membrane. Evidence for an endosomal pathway was based on findings that treatment at a pH of <6 of mature virions attached to the plasma membrane enhances entry, whereas inhibitors of endosomal acidification reduce entry. Inactivation of infectivity by low-pH treatment of virions prior to membrane attachment is characteristic of many viruses that use the endosomal route. Nevertheless, we show here that the exposure of unattached vaccinia virus virions to low pH at 37 degrees C did not alter their infectivity. Instead, such treatment stably activated virions as indicated by their accelerated entry upon subsequent addition to cells, as measured by reporter gene expression. Moreover, the rate of entry was not further enhanced by a second low-pH treatment following adsorption to the plasma membrane. However, the entry of virions activated prior to adsorption remained sensitive to inhibitors of endosomal acidification, whereas virions treated with low pH after adsorption were resistant. Activation of virions by low pH was closely mimicked by proteinase digestion, suggesting that the two treatments operate through a related mechanism. Although proteinase cleavage of the virion surface proteins D8 and A27 correlated with activation, mutant viruses constructed by individually deleting these genes did not exhibit an activated phenotype. We propose a two-step model of vaccinia virus entry through endosomes, in which activating or unmasking the fusion complex by low pH or by proteinase is rate limiting but does not eliminate a second low-pH step mediating membrane fusion. [Abstract/Link to Full Text]

Beau I, Cotte-Laffitte J, Amsellem R, Servin AL
A protein kinase A-dependent mechanism by which rotavirus affects the distribution and mRNA level of the functional tight junction-associated protein, occludin, in human differentiated intestinal Caco-2 cells.
J Virol. 2007 Aug;81(16):8579-86.
We found that at the tight junctions (TJs) of Caco-2 cell monolayers, rhesus monkey rotavirus (RRV) infection induced the disappearance of occludin. Confocal laser scanning microscopy showed the disappearance of occludin from the cell-cell boundaries without modifying the expression of the other TJ-associated proteins, ZO-1 and ZO-3. Western immunoblot analysis of RRV-infected cells showed a significant fall in the levels of the nonphosphorylated form of occludin in both Triton X-100-insoluble and Triton X-100-soluble fractions, without any change in the levels of the phosphorylated form of occludin. Quantitative reverse transcription-PCRs revealed that the level of transcription of the gene that encodes occludin was significantly reduced in RRV-infected cells. Treatment of RRV-infected cells with Rp-cyclic AMP and protein kinase A inhibitors H89 and KT5720 during the time course of the infection restored the distribution of occludin and a normal level of transcription of the gene that encodes occludin. [Abstract/Link to Full Text]

Day PM, Thompson CD, Buck CB, Pang YY, Lowy DR, Schiller JT
Neutralization of human papillomavirus with monoclonal antibodies reveals different mechanisms of inhibition.
J Virol. 2007 Aug;81(16):8784-92.
The mechanisms of human papillomavirus (HPV) neutralization by antibodies are incompletely understood. We have used HPV16 pseudovirus infection of HaCaT cells to analyze how several neutralizing monoclonal antibodies (MAbs) generated against HPV16 L1 interfere with the process of keratinocyte infection. HPV16 capsids normally bind to both the cell surface and extracellular matrix (ECM) of HaCaT cells. Surprisingly, two strongly neutralizing MAbs, V5 and E70, did not prevent attachment of capsids to the cell surface. However, they did block association with the ECM and prevented internalization of cell surface-bound capsids. In contrast, MAb U4 prevented binding to the cell surface but not to the ECM. The epitope recognized by U4 was inaccessible when virions were bound to the cell surface but became accessible after endocytosis, presumably coinciding with receptor detachment. Treatment of capsids with heparin, which is known to interfere with binding to cell surface heparan sulfate proteoglycans (HSPGs), also resulted in HPV16 localization to the ECM. These results suggest that the U4 epitope on the intercapsomeric C-terminal arm is likely to encompass the critical HSPG interaction residues for HPV16, while the V5 and E70 epitopes at the apex of the capsomer overlap the ECM-binding sites. We conclude that neutralizing antibodies can inhibit HPV infection by multiple distinct mechanisms, and understanding these mechanisms can add insight to the HPV entry processes. [Abstract/Link to Full Text]

Tani H, Komoda Y, Matsuo E, Suzuki K, Hamamoto I, Yamashita T, Moriishi K, Fujiyama K, Kanto T, Hayashi N, Owsianka A, Patel AH, Whitt MA, Matsuura Y
Replication-competent recombinant vesicular stomatitis virus encoding hepatitis C virus envelope proteins.
J Virol. 2007 Aug;81(16):8601-12.
Although in vitro replication of the hepatitis C virus (HCV) JFH1 clone of genotype 2a (HCVcc) has been developed, a robust cell culture system for the 1a and 1b genotypes, which are the most prevalent viruses in the world and resistant to interferon therapy, has not yet been established. As a surrogate virus system, pseudotype viruses transiently bearing HCV envelope proteins based on the vesicular stomatitis virus (VSV) and retrovirus have been developed. Here, we have developed a replication-competent recombinant VSV with a genome encoding unmodified HCV E1 and E2 proteins in place of the VSV envelope protein (HCVrv) in human cell lines. HCVrv and a pseudotype VSV bearing the unmodified HCV envelope proteins (HCVpv) generated in 293T or Huh7 cells exhibited high infectivity in Huh7 cells. Generation of infectious HCVrv was limited in some cell lines examined. Furthermore, HCVrv but not HCVpv was able to propagate and form foci in Huh7 cells. The infection of Huh7 cells with HCVpv and HCVrv was neutralized by anti-hCD81 and anti-E2 antibodies and by sera from chronic HCV patients. The infectivity of HCVrv was inhibited by an endoplasmic reticulum alpha-glucosidase inhibitor, N-(n-nonyl) deoxynojirimycin (Nn-DNJ), but not by a Golgi mannosidase inhibitor, deoxymannojirimycin. Focus formation of HCVrv in Huh7 cells was impaired by Nn-DNJ treatment. These results indicate that the HCVrv developed in this study can be used to study HCV envelope proteins with respect to not only the biological functions in the entry process but also their maturation step. [Abstract/Link to Full Text]

Li Q, Krogmann T, Ali MA, Tang WJ, Cohen JI
The amino terminus of varicella-zoster virus (VZV) glycoprotein E is required for binding to insulin-degrading enzyme, a VZV receptor.
J Virol. 2007 Aug;81(16):8525-32.
Varicella-zoster virus (VZV) glycoprotein E (gE) is required for VZV infection. Although gE is well conserved among alphaherpesviruses, the amino terminus of VZV gE is unique. Previously, we showed that gE interacts with insulin-degrading enzyme (IDE) and facilitates VZV infection and cell-to-cell spread of the virus. Here we define the region of VZV gE required to bind IDE. Deletion of amino acids 32 to 71 of gE, located immediately after the predicted signal peptide, resulted in loss of the ability of gE to bind IDE. A synthetic peptide corresponding to amino acids 24 to 50 of gE blocked its interaction with IDE in a concentration-dependent manner. However, a chimeric gE in which amino acids 1 to 71 of VZV gE were fused to amino acids 30 to 545 of herpes simplex virus type 2 gE did not show an increased level of binding to IDE compared with that of full-length HSV gE. Thus, amino acids 24 to 71 of gE are required for IDE binding, and the secondary structure of gE is critical for the interaction. VZV gE also forms a heterodimer with glycoprotein gI. Deletion of amino acids 163 to 208 of gE severely reduced its ability to form a complex with gI. The amino portion of IDE, as well an IDE mutant in the catalytic domain of the protein, bound to gE. Therefore, distinct motifs of VZV gE are important for binding to IDE or to gI. [Abstract/Link to Full Text]

Mori Y, Yamashita T, Tanaka Y, Tsuda Y, Abe T, Moriishi K, Matsuura Y
Processing of capsid protein by cathepsin L plays a crucial role in replication of Japanese encephalitis virus in neural and macrophage cells.
J Virol. 2007 Aug;81(16):8477-87.
The flavivirus capsid protein not only is a component of nucleocapsids but also plays a role in viral replication. In this study, we found a small capsid protein in cells infected with Japanese encephalitis virus (JEV) but not in the viral particles. The small capsid protein was shown to be generated by processing with host cysteine protease cathepsin L. An in vitro cleavage assay revealed that cathepsin L cleaves the capsid protein between amino acid residues Lys(18) and Arg(19), which are well conserved among the mosquito-borne flaviviruses. A mutant JEV resistant to the cleavage of the capsid protein by cathepsin L was generated from an infectious cDNA clone of JEV by introducing a substitution in the cleavage site. The mutant JEV exhibited growth kinetics similar to those of the wild-type JEV in monkey (Vero), mosquito (C6/36), and porcine (PK15) cell lines, whereas replication of the mutant JEV in mouse macrophage (RAW264.7) and neuroblastoma (N18) cells was impaired. Furthermore, the neurovirulence and neuroinvasiveness of the mutant JEV to mice were lower than those of the wild-type JEV. These results suggest that the processing of the JEV capsid protein by cathepsin L plays a crucial role in the replication of JEV in neural and macrophage cells, which leads to the pathogenesis of JEV infection. [Abstract/Link to Full Text]

Terenzi F, White C, Pal S, Williams BR, Sen GC
Tissue-specific and inducer-specific differential induction of ISG56 and ISG54 in mice.
J Virol. 2007 Aug;81(16):8656-65.
The interferon-stimulated genes (ISGs) ISG56 and ISG54 are strongly induced in cultured cells by type I interferons (IFNs), viruses, and double-stranded RNA (dsRNA), which activate their transcription by various signaling pathways. Here we studied the stimulus-dependent induction of both genes in vivo. dsRNA, which is generated during virus infection, induced the expression of both genes in all organs examined. Induction was not seen in STAT1-deficient mice, indicating that dsRNA-induced gene expression requires endogenous IFN. We further examined the regulation of these ISGs in several organs from mice injected with dsRNA or IFN-beta. Both ISG56 and ISG54 were widely expressed and at comparable levels. However, in organs isolated from mice injected with IFN-alpha the expression of ISG54 was reduced and more restricted in distribution compared with the expression level and distribution of ISG56. When we began to study specific cell types, splenic B cells showed ISG54 but not ISG56 expression in response to all agonists. Finally, in livers isolated from mice infected with vesicular stomatitis virus, the expression of ISG56, but not ISG54, was induced; this difference was observed at both protein and mRNA levels. These studies have revealed unexpected complexity in IFN-stimulated gene induction in vivo. For the first time we showed that the two closely related genes are expressed in a tissue-specific and inducer-specific manner. Furthermore, our findings provide the first evidence of a differential pattern of expression of ISG54 and ISG56 genes by IFN-alpha and IFN-beta. [Abstract/Link to Full Text]

Hulse-Post DJ, Franks J, Boyd K, Salomon R, Hoffmann E, Yen HL, Webby RJ, Walker D, Nguyen TD, Webster RG
Molecular changes in the polymerase genes (PA and PB1) associated with high pathogenicity of H5N1 influenza virus in mallard ducks.
J Virol. 2007 Aug;81(16):8515-24.
The highly pathogenic (HP) influenza viruses H5 and H7 are usually nonpathogenic in mallard ducks. However, the currently circulating HP H5N1 viruses acquired a different phenotype and are able to cause mortality in mallards. To establish the molecular basis of this phenotype, we cloned the human A/Vietnam/1203/04 (H5N1) influenza virus isolate that is highly pathogenic in ferrets, mice, and mallards and found it to be a heterogeneous mixture. Large-plaque isolates were highly pathogenic to ducks, mice, and ferrets, whereas small-plaque isolates were nonpathogenic in these species. Sequence analysis of the entire genome revealed that the small-plaque and the large-plaque isolates differed in the coding of five amino acids. There were two differences in the hemagglutinin (HA) gene (K52T and A544V), one in the PA gene (T515A), and two in the PB1 gene (K207R and Y436H). We inserted the amino acid changes into the wild-type reverse genetic virus construct to assess their effects on pathogenicity in vivo. The HA gene mutations and the PB1 gene K207R mutation did not alter the HP phenotype of the large-plaque virus, whereas constructs with the PA (T515A) and PB1 (Y436H) gene mutations were nonpathogenic in orally inoculated ducks. The PB1 (Y436H) construct was not efficiently transmitted in ducks, whereas the PA (T515A) construct replicated as well as the wild-type virus did and was transmitted efficiently. These results show that the PA and PB1 genes of HP H5N1 influenza viruses are associated with lethality in ducks. The mechanisms of lethality and the perpetuation of this lethal phenotype in ducks in nature remain to be determined. [Abstract/Link to Full Text]

Perera LP, Waldmann TA, Mosca JD, Baldwin N, Berzofsky JA, Oh SK
Development of smallpox vaccine candidates with integrated interleukin-15 that demonstrate superior immunogenicity, efficacy, and safety in mice.
J Virol. 2007 Aug;81(16):8774-83.
The potential use of variola virus, the etiological agent of smallpox, as a bioterror agent has heightened the interest in the reinitiation of smallpox vaccination. However, the currently licensed Dryvax vaccine, despite its documented efficacy in eradicating smallpox, is not optimal for the vaccination of contemporary populations with large numbers of individuals with immunodeficiencies because of severe adverse effects that can occur in such individuals. Therefore, the development of safer smallpox vaccines that can match the immunogenicity and efficacy of Dryvax for the vaccination of contemporary populations remains a priority. Using the Wyeth strain of vaccinia virus derived from the Dryvax vaccine, we generated a recombinant Wyeth interleukin-15 (IL-15) with integrated IL-15, a cytokine with potent immunostimulatory functions. The integration of IL-15 into the Wyeth strain resulted in a >1,000-fold reduction in lethality of vaccinated athymic nude mice and induced severalfold-higher cellular and humoral immune responses in wild-type mice that persisted longer than those induced by the parental Wyeth strain. The superior efficacy of Wyeth IL-15 was further demonstrated by the ability of vaccinated mice to fully survive a lethal intranasal challenge of virulent vaccinia virus even 10 months after vaccination, whereas all mice vaccinated with parental Wyeth strain succumbed. By integrating IL-15 into modified vaccinia virus Ankara (MVA), a virus currently under consideration as a substitute for the Dryvax vaccine, we developed a second vaccine candidate (MVA IL-15) with greater immunogenicity and efficacy than Dryvax. Thus, Wyeth IL-15 and MVA IL-15 viruses hold promise as more-efficacious and safe alternatives to the Dryvax vaccine. [Abstract/Link to Full Text]

Kim CS, Jung JH, Wakita T, Yoon SK, Jang SK
Monitoring the antiviral effect of alpha interferon on individual cells.
J Virol. 2007 Aug;81(16):8814-20.
An infectious hepatitis C virus (HCV) cDNA clone (JFH1) was generated recently. However, quantitative analysis of HCV infection and observation of infected cells have proved to be difficult because the yield of HCV in cell cultures is fairly low. We generated infectious HCV clones containing the convenient reporters green fluorescent protein (GFP) and Renilla luciferase in the NS5a-coding sequence. The new viruses responded to antiviral agents in a dose-dependent manner. Responses of individual cells containing HCV to alpha interferon (IFN-alpha) were monitored using GFP-tagged HCV and time-lapse confocal microscopy. Marked variations in the response to IFN-alpha were observed among HCV-containing cells. [Abstract/Link to Full Text]

Florez de Sessions P, Dobrikova E, Gromeier M
Genetic adaptation to untranslated region-mediated enterovirus growth deficits by mutations in the nonstructural proteins 3AB and 3CD.
J Virol. 2007 Aug;81(16):8396-405.
Both untranslated regions (UTRs) of plus-strand RNA virus genomes jointly control translation and replication of viral genomes. In the case of the Enterovirus genus of the Picornaviridae family, the 5'UTR consists of a cloverleaf-like terminus preceding the internal ribosomal entry site (IRES) and the 3' terminus is composed of a structured 3'UTR and poly(A). The IRES and poly(A) have been implicated in translation control, and all UTR structures, in addition to cis-acting genetic elements mapping to the open reading frame, have been assigned roles in RNA replication. Viral UTRs are recognized by viral and host cell RNA-binding proteins that may co-determine genome stability, translation, plus- and minus-strand RNA replication, and scaffolding of viral replication complexes within host cell substructures. In this report, we describe experiments with coxsackie B viruses with a cell type-specific propagation deficit in Sk-N-Mc neuroblastoma cells conferred by the combination of a heterologous IRES and altered 3'UTR. Serial passage of these constructs in Sk-N-Mc cells yielded genetic adaptation by mutations within the viral nonstructural proteins 3A and 3C. Our data implicate 3A and/or 3C or their precursors 3AB and/or 3CD in a functional complex with the IRES and 3'UTR that drives viral propagation. Adaptation to neuroblastoma cells suggests an involvement of cell type-specific host factors or the host cell cytoplasmic milieu in this phenomenon. [Abstract/Link to Full Text]

Ho SH, Tasca S, Shek L, Li A, Gettie A, Blanchard J, Boden D, Cheng-Mayer C
Coreceptor switch in R5-tropic simian/human immunodeficiency virus-infected macaques.
J Virol. 2007 Aug;81(16):8621-33.
The basis for the switch from CCR5 to CXCR4 coreceptor usage seen in approximately 50% of human immunodeficiency virus type 1 (HIV-1) subtype B-infected individuals as disease advances is not well understood. Among the reasons proposed are target cell limitation and better immune recognition of the CXCR4 (X4)-tropic compared to the CCR5 (R5)-tropic virus. We document here X4 virus emergence in a rhesus macaque (RM) infected with R5-tropic simian/human immunodeficiency virus, demonstrating that coreceptor switch can happen in a nonhuman primate model of HIV/AIDS. The switch to CXCR4 usage in RM requires envelope sequence changes in the V3 loop that are similar to those found in humans, suggesting that the R5-to-X4 evolution pathways in the two hosts overlap. Interestingly, compared to the inoculating R5 virus, the emerging CXCR4-using virus is highly neutralization sensitive. This finding, coupled with the observation of X4 evolution and appearance in an animal with undetectable circulating virus-specific antibody and low cellular immune responses, lends further support to an inhibitory role of antiviral immunity in HIV-1 coreceptor switch. [Abstract/Link to Full Text]

Muraki Y, Murata T, Takashita E, Matsuzaki Y, Sugawara K, Hongo S
A mutation on influenza C virus M1 protein affects virion morphology by altering the membrane affinity of the protein.
J Virol. 2007 Aug;81(16):8766-73.
Reverse genetics has been documented for influenza A, B, and Thogoto viruses belonging to the family Orthomyxoviridae. We report here the reverse genetics of influenza C virus, another member of this family. The seven viral RNA (vRNA) segments of C/Ann Arbor/1/50 were expressed in 293T cells from cloned cDNAs, together with nine influenza C virus proteins. At 48 h posttransfection, the infectious titer of the culture supernatant was determined to be 2.51 x 10(3) 50% egg infectious doses/ml, which is lower than the number of influenza C virus-like particles (VLPs) (10(6)/ml) generated using the same system. By generating influenza C VLPs containing a given vRNA segment, we showed that each of the vRNA segments was similarly synthesized in the plasmid-transfected cells but that some segments were less efficiently incorporated into the VLPs. This finding leads us to speculate that the differences in incorporation efficiency into VLPs between segments might be a reason for the inefficient production of infectious viruses. Second, we generated a mutant recombinant virus, rMG96A, which possesses an Ala-->Thr mutation at residue 24 of the M1 protein, a substitution demonstrated to be involved in the morphology (filamentous or spherical) of the influenza C VLPs. As expected, rMG96A exhibited a spherical morphology, whereas recombinant wild-type of C/Ann Arbor/1/50, rWT, exhibited a mainly filamentous morphology. Membrane flotation analysis of the cells infected with rWT or rMG96A revealed a difference in the ratio of membrane-associated M1 proteins, suggesting that the affinity of M1 protein to the cell membrane is a determinant for virion morphology. [Abstract/Link to Full Text]

Carroll KD, Khadim F, Spadavecchia S, Palmeri D, Lukac DM
Direct interactions of Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 ORF50/Rta protein with the cellular protein octamer-1 and DNA are critical for specifying transactivation of a delayed-early promoter and stimulating viral reactivation.
J Virol. 2007 Aug;81(16):8451-67.
The Kaposi's sarcoma-associated herpesvirus (KSHV) delayed-early K-bZIP promoter contains an ORF50/Rta binding site whose sequence is conserved with the ORF57 promoter. Mutation of the site in the full-length K-bZIP promoter reduced Rta-mediated transactivation by greater than 80%. The K-bZIP element contains an octamer (Oct) binding site that overlaps the Rta site and is well conserved with Oct elements found in the immediate-early promoters of herpes simplex virus type 1(HSV-1). The cellular protein Oct-1, but not Oct-2, binds to the K-bZIP element in a sequence-specific fashion in vitro and in vivo and stimulates Rta binding to the promoter DNA. The coexpression of Oct-1 enhances Rta-mediated transactivation of the wild type but not the mutant K-bZIP promoter, and Oct-1 and Rta proteins bind to each other directly in vitro. Mutations of Rta within an amino acid sequence conserved with HSV-1 virion protein 16 eliminate Rta's interactions with Oct-1 and K-bZIP promoter DNA but not RBP-Jk. The binding of Rta to both Oct-1 and DNA contributes to the transactivation of the K-bZIP promoter and viral reactivation, and Rta mutants deficient for both interactions are completely debilitated. Our data suggest that the Rta/Oct-1 interaction is essential for optimal KSHV reactivation. Transfections of mouse embryo fibroblasts and an endothelial cell line suggest cell-specific differences in the requirement for Oct-1 or RBP-Jk in Rta-mediated transactivation of the K-bZIP promoter. We propose a model in which Rta transactivation of the promoter is specified by the combination of DNA binding and interactions with several cellular DNA binding proteins including Oct-1. [Abstract/Link to Full Text]

Kim MS, Racaniello VR
Enterovirus 70 receptor utilization is controlled by capsid residues that also regulate host range and cytopathogenicity.
J Virol. 2007 Aug;81(16):8648-55.
Enterovirus type 70, an etiologic agent of acute hemorrhagic conjunctivitis, may bind different cellular receptors depending on cell type. To understand how EV70-receptor interaction is controlled, we studied two variants of the virus with distinct receptor utilization. EV70-Rmk, derived by passage in rhesus monkey kidney cells, replicates poorly in HeLa cells and does not cause cytopathic effects. Decay accelerating factor (DAF) is not a cell receptor for EV70-Rmk. Passage of EV70-Rmk in HeLa cells lead to isolation of EV70-Dne, which does not replicate in rhesus monkey kidney cells but grows to high titers in HeLa cells and causes cytopathic effects. DAF is sufficient for cell entry of EV70-Dne. EV70-Rmk replicates in human eye and brain-derived cell lines, whereas the Dne strain replicates only in HeLa cells and in conjunctiva-derived 15C4 cells. The two EV70 strains differ by five amino acid changes in the viral capsid. Single substitution of four of the five EV70-Rmk amino acids with the residue from EV70-Dne leads to lytic replication in HeLa cells. Conversely, substitution of any of the five EV70-Dne amino acids with the EV70-Rmk amino acid does not alter replication in HeLa cells. Three of these capsid amino acids are predicted to be located in the canyon encircling the fivefold axis of symmetry, one amino acid is found at the fivefold axis of symmetry, and one is located the interior of the capsid. The five EV70 residues define a region of the capsid that controls viral host range, DAF utilization, and cytopathogenicity. [Abstract/Link to Full Text]

Ikegami T, Won S, Peters CJ, Makino S
Characterization of Rift Valley fever virus transcriptional terminations.
J Virol. 2007 Aug;81(16):8421-38.
Rift Valley fever virus (RVFV) (genus Phlebovirus, family Bunyaviridae) has a tripartite negative-strand genome and causes a mosquito-borne disease among humans and livestock in sub-Saharan African and Arabian Peninsula countries. Phlebovirus L, M, and N mRNAs are synthesized from the virus-sense RNA segments, while NSs mRNA is transcribed from the anti-virus-sense S segment. The present study determined the 3' termini of all RVFV mRNAs. The 3' termini of N and NSs mRNAs were mapped within the S-segment intergenic region and were complementary to each other by 30 to 60 nucleotides. The termini of M and L mRNAs were mapped within 122 to 107 nucleotides and 16 to 41 nucleotides, respectively, from the 5' ends of their templates. Viral RNA elements that control phlebovirus transcriptional terminations are largely unknown. Our studies suggested the importance of a pentanucleotide sequence, CGUCG, for N, NSs, and M mRNA transcription terminations. Homopolymeric tracts of C sequences, which were located upstream of the pentanucleotide sequence, promoted N and M mRNA terminations. Likewise, the homopolymeric tracts of G sequences that are found upstream of the pentanucleotide sequence promoted NSs mRNA termination. The L-segment 5'-untranslated region (L-5' UTR) had neither the pentanucleotide sequence nor homopolymeric sequences, yet replacement of the S-segment intergenic region with the L-5' UTR exerted N mRNA termination in an infectious virus. The L-5' UTR contained two 13-nucleotide-long complete complementary sequences, and their sequence complementarities were important for L mRNA termination. A computer-mediated RNA secondary structure analysis further suggested that RNA secondary structures formed by the sections of the two 13-nucleotide-long sequences and by the sequence between them may have a role in L mRNA termination. Our data demonstrated that viral RNA elements that govern L mRNA termination differed from those that regulate mRNA terminations in the M and S segments. [Abstract/Link to Full Text]

Lavillette D, Pécheur EI, Donot P, Fresquet J, Molle J, Corbau R, Dreux M, Penin F, Cosset FL
Characterization of fusion determinants points to the involvement of three discrete regions of both E1 and E2 glycoproteins in the membrane fusion process of hepatitis C virus.
J Virol. 2007 Aug;81(16):8752-65.
Infection of eukaryotic cells by enveloped viruses requires the merging of viral and cellular membranes. Highly specific viral surface glycoproteins, named fusion proteins, catalyze this reaction by overcoming inherent energy barriers. Hepatitis C virus (HCV) is an enveloped virus that belongs to the genus Hepacivirus of the family Flaviviridae. Little is known about the molecular events that mediate cell entry and membrane fusion for HCV, although significant progress has been made due to recent developments in infection assays. Here, using infectious HCV pseudoparticles (HCVpp), we investigated the molecular basis of HCV membrane fusion. By searching for classical features of fusion peptides through the alignment of sequences from various HCV genotypes, we identified six regions of HCV E1 and E2 glycoproteins that present such characteristics. We introduced conserved and nonconserved amino acid substitutions in these regions and analyzed the phenotype of HCVpp generated with mutant E1E2 glycoproteins. This was achieved by (i) quantifying the infectivity of the pseudoparticles, (ii) studying the incorporation of E1E2 and their capacity to mediate receptor binding, and (iii) determining their fusion capacity in cell-cell and liposome/HCVpp fusion assays. We propose that at least three of these regions (i.e., at positions 270 to 284, 416 to 430, and 600 to 620) play a role in the membrane fusion process. These regions may contribute to the merging of viral and cellular membranes either by interacting directly with lipid membranes or by assisting the fusion process through their involvement in the conformational changes of the E1E2 complex at low pH. [Abstract/Link to Full Text]


Recent Articles in Medical Immunology

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Recent Articles in Microbiology and Immunology

Yamakawa I, Tsurudome M, Kawano M, Nishio M, Komada H, Ito M, Uji Y, Ito Y
Failure of multinucleated giant cell formation in k562 cells infected with newcastle disease virus and human parainfluenza type 2 virus.
Microbiol Immunol. 2007;51(6):601-8.
When K562 cells were infected with Newcastle disease virus (NDV) or human parainfluenza type 2 virus (hPIV-2), polykaryocyte formation could not be detected. Failure of multinucleated giant cell formation in K562 cells infected with either NDV or hPIV-2 is due to disturbance of the viral envelope-cell fusion step or to defect in the cell-cell fusion step, respectively. Especially, NDV completely replicated in K562 cells, and the hemagglutinin-neuraminidase and fusion proteins expressed on the cell surface of NDV-infected K562 cell were fully functional for fusion inducing activity. Therefore, the cell membranes of K562 cells are considered to be resistant to virus-induced cell fusion. Membrane fusion is regulated by many host factors including membrane fluidity, cytoskeletal systems, and fusion regulatory proteins system. An unknown regulatory mechanism of virus-induced cell fusion may function on the cell surface of K562 cells. [Abstract/Link to Full Text]

Naito M, Sakoda Y, Kamikawa T, Nitta Y, Hirose K, Sakashita M, Kurokawa S, Kida H
Serological evidence of leptospiral infection in pig populations in different districts in Japan.
Microbiol Immunol. 2007;51(6):593-9.
Serum samples were collected from 938 pigs of 24 farms in Hokkaido, Kagoshima, and Okinawa prefectures in Japan in 2001-2005. Enzyme-linked immunosorbent assay (ELISA) was used for the detection of antibodies to LipL32 antigen which is common to Leptospira interrogans. Samples positive in ELISA were then investigated by microscopic agglutination test for the identification of causal leptospires. Antibodies specific to leptospires of serovars Copenhageni, Bratislava, Australis and Javanica were detected in serum samples of pigs from each of the three districts. In addition, antibodies to leptospires of serovars Autumnalis and Tarassovi were predominantly detected in those from Kagoshima. The present study, thus, revealed that leptospires belonging to different serovars prevail in the pig population in Japan. In addition, it is the first detection of antibodies to leptospires belonging to serovars Javanica and Tarassovi in pigs in Japan. [Abstract/Link to Full Text]

Neri P, Nagano SI, Yokoyama S, Dohi H, Kobayashi K, Miura T, Inazu T, Sugiyama T, Nishida Y, Mori H
Neutralizing activity of polyvalent Gb3, Gb2 and galacto-trehalose models against Shiga toxins.
Microbiol Immunol. 2007;51(6):581-92.
Shiga toxin (Stx) is one of the most critical factors in the development of hemolytic uremic syndrome and other systemic complications following enterohemorrhagic Escherichia coli (EHEC) infection. Substances neutralizing Stx by interfering with toxin-receptor binding have been explored as therapeutic candidates for EHEC infection. In this study, we examined globotriaosyl (Gb3), galabiosyl (Gb2) and galacto-trehalose, each of which was synthetically conjugated with a polyacrylamide backbone, for Stxneutralizing activity. Galacto-trehalose was designed as a Gb2 mimicking, unnatural Stx-ligand that was expected to show tolerance to enzymatic degradation in vivo. Galacto-trehalose copolymer showed neutralizing activity against Stx-1 but not Stx-2 in a HeLa cell cytotoxicity assay. It was thought that galactotrehalose copolymer could be a lead compound for the treatment of Stx-mediated diseases, although it requires modification to show neutralizing activity to Stx-2. The Gb3 copolymer with high sugar unit density showed stronger neutralizing activity against Stx-2 than those with lower density. However, the density-dependency of the neutralizing activity was less obvious against Stx-1. Intravenous administration of the Gb3 copolymer prevented death in mice lethally infected with Stx-1- and Stx-2-producing E. coli O157:H7. Thus, we demonstrated that the artificial Gb3 copolymer could neutralize Stx-1 and the more clinically relevant Stx-2 in vitro and effectively inhibit Stx toxicity in vivo. [Abstract/Link to Full Text]

Ozaki H, Kida H
Extensive accumulation of influenza virus NS1 protein in the nuclei causes effective viral growth in vero cells.
Microbiol Immunol. 2007;51(5):577-80.
We previously showed that modified A/Puerto Rico/8/34 (PR8) influenza master strain had improved viral rescue and growth properties in African green monkey kidney (Vero) cell line by introducing NS gene of Vero-adapted A/England/1/53 (vaEng53). In the present study, it was found that the NS1 protein derived from vaEng53 was extensively accumulated in the nuclei than that of PR8. This accumulation was caused by 7 amino acid differences in C-terminal region of NS1 protein. These results suggest that specific accumulation of NS1 protein may contribute to efficient viral replication in Vero cells. [Abstract/Link to Full Text]

Tomita T, Ohara-Nemoto Y, Moriyama H, Ozawa A, Takeda Y, Kikuchi K
A novel in vitro pharmacokinetic/pharmacodynamic model based on two-compartment open model used to simulate serum drug concentration-time profiles.
Microbiol Immunol. 2007;51(5):567-75.
An in vitro pharmacokinetic/pharmacodynamic perfusion model that simulates a two-compartment open model of serum drug concentration-time profiles following intravenous bolus injection and infusion was developed and mathematically described. In the present apparatus model, flow was kept in a one-way mode to avoid liquid traffic, and the washout effect seen in dilution models was overcome by embedding the tested bacteria in low melting point agarose gel. The validity of the equations and the reproducibility of the apparatus model were ascertained by simulating the concentration-time profiles of cefazolin and fosfomycin by substitution of their pharmacokinetic parameters obtained from humans for the equations. An empirical regimen 1X(q24h) of 1 g with cefazolin administered by intravenous infusion effectively killed a Staphylococcus aureus strain. The same regimen with fosfomycin produced a marked kill-curve with a fosfomycin-susceptible enterohaemorrhagic Escherichia coli O157:H7, whereas considerable regrowth was observed with a resistant strain. These results indicated that the present model was able to provide a convenient and reliable method for evaluating the efficacy of antimicrobial agents administered by intravenous infusion. [Abstract/Link to Full Text]

Hoshino A, Nagao T, Ito-Ihara T, Ishida-Okawara A, Uno K, Muso E, Nagi-Miura N, Ohno N, Tokunaka K, Naoe S, Hashimoto H, Yasuhara M, Yamamoto K, Suzuki K
Trafficking of QD-conjugated MPO-ANCA in murine systemic vasculitis and glomerulonephritis model mice.
Microbiol Immunol. 2007;51(5):551-66.
In systemic vasculitis, the serum level of myeloperoxidase (MPO)-specific anti-neutrophil cytoplasmic autoantibodies (MPO-ANCA) is significantly elevated with the progression of disease. We have established a model of murine systemic vasculitis by administration of MPO-ANCA and fungal mannoprotein to C57BL/6 mice. We examined the role of MPO and MPO-ANCA in the pathogenesis of glomerulonephritis and systemic vasculitis in this model using quantum dots (QDs). We demonstrated that QD-conjugated MPO-ANCA (ANCA-QD) visualized the translocation of MPO on the neutrophil membrane surface after stimulation with proinflammatory cytokines. We also observed that MPO translocation on neutrophils in both patients with rapid progressive glomerulonephritis and these model mice without any stimulation, suggesting that MPO translocation is certain to contribute to the development of glomerular lesion. In addition, blood flow on the kidney surface vessel was significantly decelerated in both SCG/Kj mice and this model, suggesting that ANCA induces the damage of blood vessel. These results indicate that MPO-ANCA and surface-translocated MPO on the activated neutrophils coordinately plays essential roles in the initial steps of the glomerulonephritis. [Abstract/Link to Full Text]

Fukuda S, Sasaki Y, Kuwayama M, Miyazaki K
Simultaneous detection and genogroup-screening test for norovirus genogroups I and II from fecal specimens in single tube by reverse transcription- loop-mediated isothermal amplification assay.
Microbiol Immunol. 2007;51(5):547-50.
We developed a reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for the rapid detection of noroviruses (NoVs) in a genogroup-specific manner in a previous study. In this study, to detect NoVs more easily and simply, we have developed an RT-LAMP assay for the simultaneous detection of NoV genogroup I (GI) and II (GII) genomes in a single tube. The genogrouping was achieved by using fluorescence-labeled primers, and the green and red colors for GI and GII, respectively, sometimes with yellow color for GI and GII mixture, were indicated on the agarose gel under UV light at 312 nm. [Abstract/Link to Full Text]

Sugita T, Takashima M, Sano A, Nishimura K, Kinebuchi T, Yamaguchi S, Osanai H
Cryptococcus arboriformis Sp. Nov., a novel anamorphic basidiomycetous yeast species isolated from a patient's urine.
Microbiol Immunol. 2007;51(5):543-5.
A basidiomycetous yeast strain isolated from the urine of a 73-year-old Japanese patient with chronic renal failure was revealed to be a novel species by sequencing the D1/D2 26S rDNA and ITS regions of the rRNA gene. The name Cryptococcus arboriformis sp. nov. is proposed for the isolate, with IFM 54862(T) (=CBS 1044(T) =JCM 14201(T)) as the type strain. A phylogenetic analysis positioned Cryptococcus arboriformis in the Trichosporonales lineage and showed that it is closely related to C. haglerorum. [Abstract/Link to Full Text]

Hsu MC, Lin TM, Huang CT, Liao MH, Li SY
Chlamydia pneumoniae respiratory infections in Taiwan.
Microbiol Immunol. 2007;51(5):539-42.
To understand the epidemiology of Chlamydia pneumoniae acute infections in Taiwan, we collected 116 paired and 244 single sera from patients suspected of C. pneumoniae infection and conducted microimmunofluorescence test. Eighty-three patients (83/360, 23%) met the diagnostic criteria of current C. pneumoniae infection. The C. pneumoniae infections were significantly higher in men than in women (P< or =0.0001) and were most frequent in the group of 40-49 year-olds, and the people older than 70 years old. C. pneumoniae infection often occurred in the late autumn lasting to the cold winter and in the transition period between the spring and summer. [Abstract/Link to Full Text]

Boonmar S, Morita Y, Fujita M, Sangsuk L, Suthivarakom K, Padungtod P, Maruyama S, Kabeya H, Kato M, Kozawa K, Yamamoto S, Kimura H
Serotypes, antimicrobial susceptibility, and gyr A gene mutation of Campylobacter jejuni isolates from humans and chickens in Thailand.
Microbiol Immunol. 2007;51(5):531-7.
In Thailand, 51% (36/70) Campylobacter jejuni isolates from humans and 68% (47/69) isolates from poultry were classified into 10 Penner serotypes (serotype B, C, R, E, G, A, K, D, I, and L) and 9 serotypes (serotype A, C, I, K, B, E, S, D, and L), respectively. The rate of antimicrobial drug resistance to nalidixic acid, ciprofloxacin, ampicillin, tetracycline, and erythromycin shown by human isolates were 96%, 96%, 29%, 57%, and 14%, while that shown by poultry isolates were 77%, 77%, 22%, 26%, and 17%, respectively. All quinolone-resistant strains contained a mutation in the gyrA gene (T(86)-->I(86)), suggesting that the strains were already widespread in Thailand. [Abstract/Link to Full Text]

Iiyama T, Udaka K, Takeda S, Takeuchi T, Adachi YC, Ohtsuki Y, Tsuboi A, Nakatsuka S, Elisseeva OA, Oji Y, Kawakami M, Nakajima H, Nishida S, Shirakata T, Oka Y, Shuin T, Sugiyama H
WT1 (Wilms' tumor 1) peptide immunotherapy for renal cell carcinoma.
Microbiol Immunol. 2007;51(5):519-30.
Tumor-specific immunotherapy with a Wilms' tumor 1 (WT1) peptide has been on clinical trial for leukemia, myelodysplastic syndrome, breast and lung cancers and is producing promising results. In this study, we treated three patients with renal cell carcinoma with an anchor modified, HLA-A*2402 binding WT1 peptide which was emulsified in Freund's incomplete adjuvant. In two patients tumor growth was suppressed and clinical response was evaluated as stable disease by the RECIST criteria after 3 months of weekly immunizations. Notably, development of new metastases has stopped in these patients for a prolonged period. No deleterious side effects were observed. Peptide-specific T cells were expanded in PBMCs of the patients and a substantial fraction of them bore the surface phenotype consistent with a CD8+ cytotoxic effector population. Although established tumors did not regress further, considering the component of the vaccine, i.e. peptide alone, the stabilization effect suggested the potential of WT1 peptide to develop into a more effective vaccine. To our knowledge, this is the first report of WT1 immunotherapy for renal cell carcinoma. Hopefully, the results will stimulate more extensive clinical studies. [Abstract/Link to Full Text]

Akatsu H, Ishiguro M, Ogawa N, Kanesaka T, Okada N, Yamamoto T, Campbell W, Okada H
Plasma levels of unactivated thrombin activatable fibrinolysis inhibitor (TAFI) are down-regulated in young adult women: analysis of a normal Japanese population.
Microbiol Immunol. 2007;51(5):507-17.
Thrombin-activatable fibrinolysis inhibitor (TAFI) is an anaphylatoxin-inactivating enzyme generated by proteolytic cleavage of its zymogen, and is the same enzyme as that first designated by our group as procarboxypeptidase R (proCPR). TAFI in plasma is presumed to influence vascular disease in its role as a fibrinolysis inhibitor. The activity of TAFI is strongly influenced by genetic polymorphism, especially at amino acids Thr/Ala-147 and Thr/Ile-325. In this study, we analyzed 202 healthy controls who were not on any medication, had no unusual medical history and whose blood data were normal. In a previous report, we established an enzyme-linked immunosorbent assay (ELISA) specific for non-activated TAFI (proCPR), and investigated levels of unactivated TAFI as an estimate of anti-fibrinolytic capacity. In this study, we determined normal Japanese TAFI levels for each age, sex, and genetic polymorphism of Thr/Ala-147 and Thr/Ile-325, and also showed that the TAFI level in young adult women is lower than in aged women. [Abstract/Link to Full Text]

Ishibashi H, Hisajima T, Hu W, Yamaguchi H, Nishiyama Y, Abe S
A murine model of esophageal candidiasis with local characteristic symptoms.
Microbiol Immunol. 2007;51(5):501-6.
A simple method to establish a murine esophageal candidiasis model that displayed characteristic symptoms of the condition was developed using the sedative agent, chlorpromazine. Mice were immunosuppressed with prednisolone and were given tetracycline hydrochloride. One day later, the mice received chlorpromazine to keep them in a sedated state for about 3 hr. Under the sedated condition, they were infected with 4 x 10(7) viable cells of Candida albicans by intra-esophageal injection with a round-head needle on syringe. From day 3 to day 6 post inoculation, 10(5)-10(6) colony forming units of C. albicans were recovered from the esophageal tube of each mouse and whitish, curd-like patches were observed on most of the inner surface of the tube. Histological examination showed that C. albicans in esophageal lesions grew mainly in mycelial form. In this experimental model, intragastric administration of an itraconazole oral solution (20 mg/kg/day) was clearly effective. This model would provide a useful tool to investigate the pathogenesis of C. albicans esophageal infection and the efficacy of various antifungal agents microbiologically and symptomatically. [Abstract/Link to Full Text]

Harada K, Asai T, Kojima A, Sameshima T, Takahashi T
Contribution of multi-antimicrobial resistance to the population of antimicrobial resistant Escherichia coli isolated from apparently healthy pigs in Japan.
Microbiol Immunol. 2007;51(5):493-9.
The aim of this study was to clarify the involvement of tetracycline usage in resistance rates against other antimicrobials. Antimicrobial susceptibility testing was carried out on 545 porcine Escherichia coli isolates throughout Japan. As the result of analyzing by regions, resistance rates against kanamycin, oxytetracycline and trimethoprim in the Kanto/Koshinetu district were higher than those in some other districts. High resistance rates against kanamycin or trimethoprim in oxytetracycline-resistant isolates were also observed in the Kanto/Koshinetu district. The prevalence of multi-antimicrobial resistance through co-selection of resistances against kanamycin or trimethoprim by tetracycline usage could be the cause of regional differences in these resistances in porcine E. coli. By a communicative surveillance, kanamycin- and trimethoprim-resistance rates were likely to be elevated with tetracycline usage. Thus, usage of specific antimicrobial(s) is a remarkable viewpoint to control antimicrobial resistant bacteria. [Abstract/Link to Full Text]

Saiki K, Konishi K
Identification of a Porphyromonas gingivalis novel protein sov required for the secretion of gingipains.
Microbiol Immunol. 2007;51(5):483-91.
Gingipains are extracellular proteases important for the virulence of Porphyromonas gingivalis; however, the mechanism for the secretion of gingipains is poorly understood. In this report, we found that insertion mutants for PG0809 (83K1 and 83K2) were defective in black pigmentation and hemolysis. We cloned and sequenced PG0809 and found that PG0809 contains two additional nucleotides that are not deposited in the W83 genome database. The revised sequence reveals an in-frame fusion of PG0810 and PG0809 and is designated the sov gene. We constructed a sov deletion mutant (83K3) and showed that 83K3 was defective in the activities of black pigmentation, hemolysis, and hemagglutination. Furthermore, in 83K3, the activities of gingipains were severely reduced whereas those of other secreted proteases DPPIV, DPP-7, and PtpA were not affected. Immunoblot analysis using anti-RgpB antiserum showed that Arg-gingipains were poorly secreted in an outer membrane or into an extracellular portion but accumulated within the cells of 83K3, suggesting the secretion of gingipains is defected in 83K3. Taken together, our findings indicated that Sov is a novel protein required for the secretion of gingipains and suggested that the secretion system for gingipains is different from the conserved secretion systems. [Abstract/Link to Full Text]

El-Shamy A, Sasayama M, Nagano-Fujii M, Sasase N, Imoto S, Kim SR, Hotta H
Prediction of efficient virological response to pegylated interferon/ribavirin combination therapy by NS5A sequences of hepatitis C virus and anti-NS5A antibodies in pre-treatment sera.
Microbiol Immunol. 2007;51(4):471-82.
A considerable number of patients infected with Hepatitis C virus subtype 1b (HCV-1b) do not respond to pegylated interferon/ribavirin combination therapy. In this study we explored a useful factor(s) to predict treatment outcome. A total of 47 HCV-1b-infected patients were treated with pegylated interferon/ ribavirin for 48 weeks. Sera of the patients were examined for the entire NS5A sequence of the HCV genome, HCV RNA titers and anti-NS5A antibodies. According to their responses, the patients were divided into two groups, early viral responders who cleared the virus by week 16 (EVR[16w]) and those who did not (Non-EVR[16w]). The mean number of mutations in the V3 region (aa 2356 to 2379) or that in the V3 region plus its N-terminally flanking region, which we refer to as interferon/ribavirin resistancedetermining region (IRRDR; aa 2334 to 2379), of NS5A obtained from the pretreatment sera was signifi-cantly larger for EVR(16w) compared with Non-EVR(16w). Moreover, HCV-1b isolates with > or =5 mutations in V3 or those with > or =6 mutations in IRRDR were almost exclusively found in EVR(16w). Also, the presence of detectable levels of anti-NS5A antibodies in the pretreatment sera was closely associated with EVR(16w). In conclusion, a high degree of sequence variation in V3 (> or =5) or IRRDR (> or =6) and the presence of detectable levels of anti-NS5A antibodies in the pretreatment sera would be useful factors to predict EVR(16w). On the other hand, a less diverse sequence in V3 (< or =4) or IRRDR (< or =5) together with the absence of detectable anti-NS5A antibodies could be a predictive factor for Non-EVR(16w). [Abstract/Link to Full Text]

Okuda J, Ramamurthy T, Yamasaki S
The potent antibacterial activity of Sitafloxacin against fluoroquinolone-resistant clinical isolates of Vibrio cholerae O1.
Microbiol Immunol. 2007;51(4):467-9.
The in vitro antibacterial activity of sitafloxacin using clinical isolates of Vibrio cholerae O1 was compared to other fluoroquinolones: ciprofloxacin, ofloxacin, sparfloxacin and levofloxacin. Against fluoroquinolone-resistant O1 strains, sitafloxacin was 4- to 16-fold more effective than other fluoroquinolones at MIC(90*). Against fluoroquinolone-susceptible O1 strains, the MIC(90) of sitafloxacin was 2- to 4-fold lower than other fluoroquinolones. This suggests sitafloxacin can be used in the treatment of infections caused by V. cholerae O1 strains including the fluoroquinolone-resistant strains. [Abstract/Link to Full Text]

Nishimura T, Sakudo A, Hashiyama Y, Yachi A, Saeki K, Matsumoto Y, Ogawa M, Sakaguchi S, Itohara S, Onodera T
Serum withdrawal-induced apoptosis in ZrchI prion protein (PrP) gene-deficient neuronal cell line is suppressed by PrP, independent of Doppel.
Microbiol Immunol. 2007;51(4):457-66.
Previous studies have shown that cellular prion protein (PrP(C)) plays anti-apoptotic and antioxidative role against cell death induced by serum-deprivation (SDP) in an immortalized prion protein gene-deficient neuronal cell line derived from Rikn prion protein (PrP) gene-deficient (Prnp(-/-)) mice, which ectopically produce excess Doppel (Dpl) (PrP-like glycoprotein). To investigate whether PrP(C) inhibits apoptotic neuronal cell death without Dpl, an immortalized cell line was established from the brain of ZrchI Prnp(-/-) mice, which do not show ectopic expression of Dpl. The results using a ZrchI neuronal Prnp(-/-) cell line (NpL2) showed that PrP(C) potently inhibited SDP-induced apoptotic cell death. Furthermore, PrP(C) expression enhanced the superoxide dismutase (SOD) activity in NpL2 cells. These results indicate that Dpl production did not affect anti-apoptotic and anti-oxidative functions of PrP, suggesting that PrP(C) may be directly correlated with protection against oxidative stress. [Abstract/Link to Full Text]

Lee JC, Hwang HJ, Sakaguchi Y, Yamamoto Y, Arimitsu H, Tsuji T, Watanabe T, Ohyama T, Tsuchiya T, Oguma K
C terminal half fragment (50 kDa) of heavy chain components of Clostridium botulinum type C and D neurotoxins can be used as an effective vaccine.
Microbiol Immunol. 2007;51(4):445-55.
Recombinant whole heavy chains (H, 100 kDa) and their N-terminal (Hn, 50 kDa) and C-terminal (Hc, 50 kDa) half fragments of Clostridium botulinum type C and D neurotoxins were expressed as glutathione S-transferase (GST) fusion proteins in Escherichia coli. GST eliminated-preparations of H (10 microg), Hn (5 microg), Hc (5 microg), or a mixture of Hn (5 microg) and Hc (5 microg) of types C and D were mixed with an equal volume of adjuvant, and then were twice injected into mice subcutaneously. After immunization, the mice were challenged with up to 10(6) the minimum lethal doses (MLD)/0.5 ml of C or D toxin, the type of which was same as that of the immunogens. All of the mice immunized with antigens except for Hn survived against 10(5) to 10(6) MLD/0.5 ml of the toxins, but the mice immunized with Hn were killed by 100 MLD/0.5 ml. The mice immunized with a mixture of C-Hc and D-Hc, each 5 microg, also showed a high level of resistance against both C and D toxins. Antibody levels immunized with GST fused-or GST eliminatedpreparation were quite similar. These results indicate that recombinant GST-fused Hc can be used as a safe and effective vaccine for type C and D botulism in animals. It also became clear that one time inoculation with a large amount of C-Hc or D-Hc, 100 microg, is useful for vaccine trials in mice. [Abstract/Link to Full Text]

Okada N, Asai S, Hotta A, Miura N, Ohno N, Farkas I, Hau L, Okada H
Increased inhibitory capacity of an anti-C5a complementary peptide following acetylation of N-terminal alanine.
Microbiol Immunol. 2007;51(4):439-43.
Amino acids 37 to 53 (RAARISLGPRCIKAFTE) of C5a anaphylatoxin form an essential region for C5a function. To target this sequence, we generated a complementary peptide (ASGAPAPGPAGPLRPMF) designated PepA which has a potent inhibitory effect on C5a activity. By introducing an acetyl group at the N-terminal alanine of PepA, an acetylated form was generated which was designated AcPepA. The acetylation resulted in increased inhibition of C5a stimulation of neutrophils as determined by Ca influx. Furthermore, AcPepA partially inhibited the lethal shock induced in mice by intravenous administration of Candida albicans water-soluble mannoprotein-beta-glucan complex. In addition, local skin inflammation in rats caused by an anti-Crry monoclonal antibody was suppressed when AcPepA and the antibody were injected together, while PepA had little inhibitory capacity. The potent inhibitory capacity of AcPepA was also confirmed by a skin reaction of guinea pigs inoculated with recombinant human C5a together with AcPepA. [Abstract/Link to Full Text]

Hinenoya A, Nagita A, Asakura M, Tsukamoto T, Ramamurthy T, Nair GB, Takeda Y, Yamasaki S
Cytolethal distending toxin (Cdt)-producing escherichia coli isolated from a child with bloody diarrhea in Japan.
Microbiol Immunol. 2007;51(4):435-8.
In a retrospective analysis by PCR, the cdtI gene encoding the cytolethal distending toxin (Cdt) was detected in Escherichia coli O2:H12 strain isolated from the bloody diarrheal stool specimen of a child. To our knowledge, this is the first report showing the possible association of Cdt-producing E. coli in Japan, particularly in a child with bloody diarrhea. [Abstract/Link to Full Text]

Hasegawa H, Tanikawa T, Nozawa T, Nakazawa K, Nakagawa Y, Matsuyama T
Distinct function of Pseudomonas aeruginosa type IV pili disclosed in the bacterial pass-through of membrane filter with smaller pore sizes.
Microbiol Immunol. 2007;51(4):429-33.
Membrane filter pass-through ability of Pseudomonas aeruginosa was analyzed with isogenic mutants. A flagellum-deficient fliC mutant required two-times longer time (12 hr) to pass through a 0.45-microm pore size filter. With 0.3- and 0.22-microm filters, however, the fliC mutant showed no remarkable disability. Meanwhile a pilA mutant defective in twitching motility failed to pass through the 0.22-microm filter. Complementation of the mutant with pilA gene on a plasmid restored the twitching motility and the 0.22-microm filter pass-through activity. Thus, the distinctive role of P. aeruginosa type IV pili in infiltration into finer reticulate structures was indicated. [Abstract/Link to Full Text]

Kurokawa CS, Araujo JP, Soares AM, Sugizaki MF, Peraçoli MT
Pro- and anti-inflammatory cytokines produced by human monocytes challenged in vitro with Paracoccidioides brasiliensis.
Microbiol Immunol. 2007;51(4):421-8.
Monocytes and macrophages play a central role in innate and adaptive immune response against systemic fungal infections. Imbalances in suppressor or stimulatory cytokine secretion caused by these cells may influence disease development, microorganism death, and the nature of the adaptive immune response. This study analyzed the monocyte cytokine profiles of healthy individuals challenged with high and low virulent strains of P. brasiliensis and mRNA cytokine expression kinetics by reverse transcription polymerase chain reaction (RT-PCR). Peripheral blood monocytes from healthy volunteers were cultured in vitro with and without virulent (Pb18) or low virulence (Pb265) strains from P. brasiliensis viable yeast cells. Interleukin-1 beta (IL-1beta), IL-6, IL-8, IL-10, tumor necrosis factor-alpha (TNF-alpha), and transforming growth factor-beta (TGF-beta1) were measured in culture supernatants by enzyme immunoassay (ELISA), and mRNA cytokine expression was determined by RT-PCR at 0, 4, 8, 12, 18 and 48 hr. Both P. brasiliensis strains induced monocyte production of IL-1beta, IL-6, IL-10 and TNF-alpha. Pb18 induced higher levels of IL-1beta, IL-6, and IL-10 than Pb265. IL-8 and TGF-beta1 levels were not significantly different from those cultured without stimulus. The mRNA cytokine expression was similar to supernatant cytokines measured by ELISA. In vitro monocyte challenge with virulent P. brasiliensis strain induces earlier and higher levels of pro- and anti-inflammatory cytokines than low virulence strain. [Abstract/Link to Full Text]

Higurashi H, Arai M, Watanabe A, Igari H, Seki N, Kamei K, Kuriyama T
Gene expression profiling of polymorphonuclear leukocytes treated with the culture filtrate of Aspergillus fumigatus and gliotoxin.
Microbiol Immunol. 2007;51(4):407-19.
Pathogens of the Aspergillus species are frequently seen in deep-seated mycoses. We previously demonstrated that the culture filtrate of Aspergillus fumigatus (CF) has immunosuppressive effects on polymorphonuclear leukocytes (PMNs), which act as the main phagocytes to hyphae of Aspergillus fumigatus (A. fumigatus). But little is known about the gene expression profiles involved in it. Therefore we investigated the changes in gene expression in human PMNs treated with CF or gliotoxin at two time points, using microarray analysis. CF and gliotoxin changed the expression of 548 and 381 genes, respectively. Only 51 genes showed the same expression patterns with the two stimulants, and CF-induced changes in gene expression occurred comparatively earlier than those induced by gliotoxin. Among 31 genes encoding apoptosis, which were up- or down-regulated in this assay, only 3 genes were similarly changed by both kinds of stimulation. Apoptosis was detected and quantified using two apoptosis assays. CF and gliotoxin changed the expessions of only 3 out of 19 regulated genes related to inflammatory mediators and receptors similarly. The up-regulation of the gene encoding annexin 1 (ANXA1), which is known to be involved in extravasation and apoptosis of neutrophils, may play a role in the immunosuppressive effect of A. fumigatus. The difference in expression changes between CF and gliotoxin is presumed to be caused by the interaction among the components of CF and therefore the interaction is an area of interest for further investigation. [Abstract/Link to Full Text]

Hirayama T, Nagano I, Shinmoto H, Yagyu K, Oshima S
Isolation and characterization of virulent yellowtail ascites virus.
Microbiol Immunol. 2007;51(4):397-406.
Yellowtail ascites virus (YTAV) is the causative agent of ascites and deformity in fish and causes serious losses to the fish-farming industry of yellowtail fry and fingerling Seriola quinqueradiata in Japan. In 2006, cultured yellowtail died from ascites in Kochi, Japan. We isolated and characterized a virus from the diseased fish. Based on the pathogenicity, culture characteristics, morphological features, RT-PCR results targeting VP2/NS region, phylogeny based on the VP1 amino acid sequence, and immunochemical reactivity of structural proteins, the virus isolate was identified as YTAV (designated as YTAV-06). YTAV-06 was a more virulent isolate than YTAV Y-6, isolated originally from yellowtail with ascites. To our knowledge, this is the first report describing that YTAV isolates may vary in their virulence. [Abstract/Link to Full Text]

Jeon B, Itoh K
Production of shiga toxin by a luxS mutant of Escherichia coli O157:H7 in vivo and in vitro.
Microbiol Immunol. 2007;51(4):391-6.
Quorum sensing is a type of bacterial communication mediated by chemical signaling molecules called autoinducers (AIs). The production of AI-2 and AI-3 is dependent on the luxS gene in Escherichia coli O157:H7. A luxS mutation caused a minimal decrease (about 2-fold) in Shiga toxin (Stx) production in in vitro cultures using Luria-Bertani broth. The effect of a luxS mutation on the virulence of E. coli O157:H7 was examined by using germfree mice. There were no differences between the luxS mutant and the wild-type in the bacterial counts in feces shedding, Stx production, or the survival of the mice. The treatment of ciprofloxacin decreased the bacteria in feces but increased the Stx production. However, even treatment with ciprofloxacin did not make any difference between the luxS mutant and the wild-type in animal experiments. [Abstract/Link to Full Text]

da Cunha Mde L, Calsolari RA, Júnior JP
Detection of enterotoxin and toxic shock syndrome toxin 1 genes in Staphylococcus, with emphasis on coagulase-negative staphylococci.
Microbiol Immunol. 2007;51(4):381-90.
The detection of staphylococcal enterotoxins is decisive for the confirmation of an outbreak and for the determination of the enterotoxigenicity of strains. Since the recognition of their antigenicity, a large number of serological methods for the detection of enterotoxins in food and culture media have been proposed. Since immunological methods require detectable amounts of toxin, molecular biology techniques represent important tools in the microbiology laboratory. In the present study, polymerase chain reaction (PCR) was used to identify genes responsible for the production of enterotoxins and toxic shock syndrome toxin 1 (TSST-1) in S. aureus and coagulase-negative staphylococci (CNS) isolated from patients and the results were compared with those obtained by the reverse passive latex agglutination (RPLA) assay. PCR detection of toxin genes revealed a higher percentage of toxigenic S. aureus strains (46.7%) than the RPLA method (38.3%). Analysis of the toxigenic profile of CNS strains showed that 26.7% of the isolates produced some type of toxin, and one or more toxin-specific genes were detected in 40% of the isolates. These results suggests the need for further studies in order to better characterize the pathogenic potential of CNS and indicate that attention should be paid to the toxigenic capacity of this group of microorganisms. [Abstract/Link to Full Text]

Islam MS, Jahid MI, Rahman MM, Rahman MZ, Islam MS, Kabir MS, Sack DA, Schoolnik GK
Biofilm acts as a microenvironment for plankton-associated Vibrio cholerae in the aquatic environment of Bangladesh.
Microbiol Immunol. 2007;51(4):369-79.
The role of biofilm as a microenvironment of plankton-associated Vibrio cholerae was investigated using plexiglass as a bait. A total of 72 biofilm samples were tested using culture, direct fluorescent antibody (DFA) and molecular techniques following standard procedures. Culturable V. cholerae (smooth and rugose variants) were isolated from 33% of the samples. V. cholerae O1 were detected by FA technique throughout the year except April and June. All V. cholerae O1 isolates were positive for tcpA, ctxA and ace genes while V. cholerae non-O1, non-O139 isolates lacked these genes. V. cholerae O1 (both Inaba and Ogawa) strains had identical ribotype pattern (R1), but V. cholerae non-O1, non-O139 had different ribotype patterns. All V. cholerae O1 strains were resistant to vibrio-static compound (O/129). All V. cholerae O1 except one were resistant to trimethoprime-sulphamethoxazole, streptomycin, nalidixic acid and furazolidone but sensitive to ciprofloxacin, and tetracycline. This study indicates that plexiglass can act as a bait to form biofilm, a microenvironment that provides shelter for plankton containing V. cholerae in the aquatic environment of Bangladesh. [Abstract/Link to Full Text]

Tabara K, Arai S, Kawabuchi T, Itagaki A, Ishihara C, Satoh H, Okabe N, Tsuji M
Molecular survey of Babesia microti, Ehrlichia species and Candidatus neoehrlichia mikurensis in wild rodents from Shimane Prefecture, Japan.
Microbiol Immunol. 2007;51(4):359-67.
A significant number of patients are diagnosed with "fevers of unknown origin" (FUO) in Shimane Prefecture in Japan where tick-borne diseases are endemic. We conducted molecular surveys for Babesia microti, Ehrlichia species, and Candidatus Neoehrlichia mikurensis in 62 FUO cases and 62 wild rodents from Shimane Prefecture, Japan. PCR using primers specific for the Babesia 18S small-subunit rRNA (rDNA) gene and Anaplasmataceae groESL amplified products from 45% (28/62) and 25.8% (16/62) of captured mice, respectively. Of the 28 18S rDNA PCR positives, 23 and five samples were positive for Hobetsu- and Kobe-type B. microti, respectively. In contrast, of the 16 groESL PCR positives, eight, one and seven samples were positive for Ehrlichia muris, Ehrlichia sp. HF565 and Candidatus N. mikurensis, respectively. Inoculation of selected blood samples into Golden Syrian hamsters indicated the presence of Hobetsu- and Kobe-type B. microti in four and one sample, respectively. Isolation of the latter strain was considered important as previous studies suggested that the distribution of this type was so far confined to Awaji Island in Hyogo Prefecture, where the first case of transfusion-associated human babesiosis originated. DNA samples from 62 FUO human cases tested negative for B. microti 18S rDNA gene, Anaplasmataceae groESL gene, Rickettsia japonica 17K genus-common antigen gene and Orientia tsutsugamushi 56K antigen gene by PCRs. We also conducted seroepidemiological surveys on 62 human sera collected in Shimane Prefecture from the FUO patients who were suspected of carrying tick-borne diseases. However, indirect immunofluorescent antibody tests using B. microti- and E. muris-infected cells detected IgG against E. muris in only a single positive sample. This study demonstrates the presence of several potentially important tick-borne pathogens in Shimane Prefecture and suggests the need for further study on the causative agents of FUOs. [Abstract/Link to Full Text]

Kibe R, Sakamoto M, Yokota H, Benno Y
Characterization of the inhabitancy of mouse intestinal bacteria (MIB) in rodents and humans by real-time PCR with group-specific primers.
Microbiol Immunol. 2007;51(4):349-57.
Mouse intestinal bacteria (MIB) is a new operational taxonomic unit (OTU) belonging to the Bacteroides subgroup in the Cytophaga-Flavobacter-Bacteroides (CFB) phylum recently found in the intestine of mice, rats and humans. However, their characters are still unknown since they have not yet been isolated by culture. To understand their habitat characteristics in intestinal tracts, the quantification assays of MIB were established using MIB group-specific primers. The MIB population in the intestine was evaluated as a percentage of the number of 16S rRNA gene copy of MIB. A real-time PCR assay using group specific primers showed the fluctuation of MIB inhabitancy and revealed that the MIB population in the small intestine of mice was significantly lower than the large intestinal contents. Moreover, MIB was found in human feces though the number was lower than in murine. This assay using group-specific primers revealed new information about host-preference of MIB. [Abstract/Link to Full Text]


Recent Articles in International Microbiology

de Los Ríos A, Ascaso C
Contributions of in situ microscopy to the current understanding of stone biodeterioration.
Int Microbiol. 2005 Sep;8(3):181-8.
In situ microscopy consists of simultaneously applying several microscopy techniques without separating the biological component from its habitat. Over the past few years, this strategy has allowed characterization of the biofilms involved in biodeterioration processes affecting stone monuments and has revealed the biogeophysical and biogeochemical impact of the microbiota present. In addition, through in situ microscopy diagnosis, appropriate treatments can be designed to resolve the problems related to microbial colonization of stone monuments. [Abstract/Link to Full Text]

Videla HA, Herrera LK
Microbiologically influenced corrosion: looking to the future.
Int Microbiol. 2005 Sep;8(3):169-80.
This review discusses the state-of-the-art of research into biocorrosion and the biofouling of metals and alloys of industrial usage. The key concepts needed to understand the main effects of microorganisms on metal decay, and current trends in monitoring and control strategies to mitigate the deleterious effects of biocorrosion and biofouling are also described. Several relevant cases of biocorrosion studied by our research group are provided as examples: (i) biocorrosion of aluminum and its alloys by fungal contaminants of jet fuels; (ii) sulfate-reducing bacteria (SRB)-induced corrosion of steel; (iii) biocorrosion and biofouling interactions in the marine environment; (iv) monitoring strategies for assessing biocorrosion in industrial water systems; (v) microbial inhibition of corrosion; (vi) use and limitations of electrochemical techniques for evaluating biocorrosion effects. Future prospects in the field are described with respect to the potential of innovative techniques in microscopy (environmental scanning electron microscopy, confocal scanning laser microscopy, atomic force microscopy), new spectroscopic techniques for the study of corrosion products and biofilms (energy dispersion X-ray analysis, X-ray photoelectron spectroscopy, electron microprobe analysis) and electrochemistry (electrochemical impedance spectroscopy, electrochemical noise analysis). [Abstract/Link to Full Text]

Beech IB, Sunner JA, Hiraoka K
Microbe-surface interactions in biofouling and biocorrosion processes.
Int Microbiol. 2005 Sep;8(3):157-68.
The presence of microorganisms on material surfaces can have a profound effect on materials performance. Surface-associated microbial growth, i.e. a biofilm, is known to instigate biofouling. The presence of biofilms may promote interfacial physico-chemical reactions that are not favored under abiotic conditions. In the case of metallic materials, undesirable changes in material properties due to a biofilm (or a biofouling layer) are referred to as biocorrosion or microbially influenced corrosion (MIC). Biofouling and biocorrosion occur in aquatic and terrestrial habitats varying in nutrient content, temperature, pressure and pH. Interfacial chemistry in such systems reflects a wide variety of physiological activities carried out by diverse microbial populations thriving within biofilms. Biocorrosion can be viewed as a consequence of coupled biological and abiotic electron-transfer reactions, i.e. redox reactions of metals, enabled by microbial ecology. Microbially produced extracellular polymeric substances (EPS), which comprise different macromolecules, mediate initial cell adhesion to the material surface and constitute a biofilm matrix. Despite their unquestionable importance in biofilm development, the extent to which EPS contribute to biocorrosion is not well-understood. This review offers a current perspective on material/microbe interactions pertinent to biocorrosion and biofouling, with EPS as a focal point, while emphasizing the role atomic force spectroscopy and mass spectrometry techniques can play in elucidating such interactions. [Abstract/Link to Full Text]

Laborda F
In Memoriam Harold W. Rossmoore (1925-2003): a personal view.
Int Microbiol. 2005 Sep;8(3):155-6. [Abstract/Link to Full Text]


Proceedings of the 13th International Biodeterioration and Biodegradation Symposium, Madrid, Spain, 4-9 September 2005.
Int Microbiol. 2005 Sep;8(3):153-230. [Abstract/Link to Full Text]

Margulis L
Hans Ris (1914-2004). Genophore, chromosomes and the bacterial origin of chloroplasts.
Int Microbiol. 2005 Jun;8(2):145-8. [Abstract/Link to Full Text]

Fraga-Medín C, Jiménez-Planet V, Mohedano-Macías L, de Cabo JV
The Virtual Health Library of Spain: a tool to access and disseminate scientific and technical knowledge on health.
Int Microbiol. 2005 Jun;8(2):141-4. [Abstract/Link to Full Text]

Maymó-Gatell X
Fundamental things apply: the case of Dehalococcoides ethenogenes.
Int Microbiol. 2005 Jun;8(2):137-40. [Abstract/Link to Full Text]

Alcoba-Flórez J, Pérz-Roth E, González-Linares S, Méndez-Alvarez S
Outbreak of Shigella sonnei in a rural hotel in La Gomera, Canary Islands, Spain.
Int Microbiol. 2005 Jun;8(2):133-6.
Shigella sonnei is a significant cause of gastroenteritis in both developing and industrialized countries. Knowledge of the diversity and antimicrobial susceptibility of the bacterium may be helpful in the management of both individual cases and outbreaks. This study was undertaken to evaluate the molecular epidemiology of an outbreak of diarrhea due to S. sonnei. The outbreak involved 14 of 28 (50%) tourists in a small rural hotel in La Gomera, Canary Islands, Spain. All of the S. sonnei isolates recovered had the same antimicrobial susceptibility and pulsed-field gel electrophoresis patterns, suggesting that the outbreak was produced by a single strain. [Abstract/Link to Full Text]

Bizani D, Motta AS, Morrissy JA, Terra RM, Souto AA, Brandelli A
Antibacterial activity of cerein 8A, a bacteriocin-like peptide produced by Bacillus cereus.
Int Microbiol. 2005 Jun;8(2):125-31.
The mode of action of cerein 8A, a bacteriocin produced by the soil bacterium Bacillus cereus 8A, was investigated. The effect of cerein 8A was tested against Listeria monocytogenes and a bactericidal effect at 400 arbitrary units (AU)/ml was observed. In addition, cerein 8A was bactericidal against Bacillus cereus at 200 AU/ml, and inhibited the growth of Escherichia coli and Salmonella Enteritidis. Stronger inhibition of these gram-negative bacteria was achieved when the chelating agent EDTA was added together with bacteriocin. The effect of cerein 8A on B. cereus and L. monocytogenes was also investigated by Fourier transform infrared spectroscopy (FTIR). Treated cells had an important frequency increase at 2920 cm-1 and a decrease at 1400 cm-1, corresponding to assignments of fatty acids. Transmission electron microscopy showed damaged cell walls and loss of protoplasmic material. These results suggest that the mode of action of cerein 8A is to interfere with cell membranes and the cell wall. [Abstract/Link to Full Text]

Tonkic M, Goic-Barisic I, Punda-Polic V
Prevalence and antimicrobial resistance of extended-spectrum beta-lactamases-producing Escherichia coli and Klebsiella pneumoniae strains isolated in a university hospital in Split, Croatia.
Int Microbiol. 2005 Jun;8(2):119-24.
The prevalence of Escherichia coli and Klebsiella pneumoniae that produce extended-spectrum b-lactamases (ESBL) was investigated in patients of a university hospital in Split, Croatia. Patients were grouped according to age (pediatric vs. adult), antibiotic type, and hospital ward. From Jan. 2001 to Dec. 2002, the susceptibility of E. coli and K. pneumoniae isolates to antimicrobials was tested. ESBL production was assayed using the double-disk synergy test. ESBL-producing E. coli and K. pneumoniae were detected in all sites of infection sampled. The percentages of ESBL-positive isolates were higher in the pediatric wards than in the adult wards. The antibiotics most commonly prescribed to patients in all hospital wards belonged to the third-generation cephalosporin group. Among ESBL producers, E. coli isolates were more resistant to aminoglycosides, but less resistant to ciprofloxacin and cotrimoxazole. Resistance of E. coli and K. pneumoniae to ciprofloxacin was exclusively found in isolates from adult patients. None of the isolates, regardless of ESBL production, was resistant to carbapenemes. In addition, the prevalence and antimicrobial resistance of ESBL-producing E. coli and K. pneumoniae isolates differed between pediatric and adult patients. [Abstract/Link to Full Text]

Keim CN, Solórzano G, Farina M, Lins U
Intracellular inclusions of uncultured magnetotactic bacteria.
Int Microbiol. 2005 Jun;8(2):111-7.
Magnetotactic bacteria produce magnetic crystals in organelles called magnetosomes. The bacterial cells may also have phosphorus-containing granules, sulfur globules, or polyhydroxyalkanoate inclusions. In the present study, the ultrastructure and elemental composition of intracellular inclusions from uncultured magnetotactic bacteria collected in a marine environment are described. Magnetosomes contained mainly defect-free, single magnetite crystals with prismatic morphologies. Two types of phosphorus-containing granules were found in magnetotactic cocci. The most common consisted of phosphorus-rich granules containing P, O, and Mg; and sometimes also C, Na, Al, K, Ca, Mn, Fe, Zn, and small amounts of S and Cl were also found. In phosphorus-sulfur-iron granules, P, O, S, Na, Mg, Ca, Fe, and frequently Cl, K, and Zn, were detected. Most cells had two phosphorus-rich granules, which were very similar in elemental composition. In rod-shaped bacteria, these granules were positioned at a specific location in the cell, suggesting a high level of intracellular organization. Polyhydroxyalkanoate granules and sulfur globules were less commonly seen in the cells and had no fixed number or specific location. The presence and composition of these intracellular structures provide clues regarding the physiology of the bacteria that harbor them and the characteristics of the microenvironments where they thrive. [Abstract/Link to Full Text]

Calvó L, Cortey M, García-Marin JL, Garcia-Gil LJ
Polygenic analysis of ammonia-oxidizing bacteria using 16S rDNA, amoA, and amoB genes.
Int Microbiol. 2005 Jun;8(2):103-10.
Finding a unique molecular marker capable of quickly providing rigorous and useful phylogenetic information would facilitate assessing the diversity of ammonia-oxidizing bacteria in environmental samples. Since only one of several available markers can be used at a time in these kinds of studies, the 16S rDNA, amoA and amoB genes were evaluated individually and then compared in order to identify the one that best fits the information provided by the composite dataset. Distance-based neighbor-joining and maximum parsimony trees generated using the sequences of the three mentioned genes were analyzed with respect to the combined polygenic trees. Maximum parsimony trees were found to be more accurate than distance-based ones, and the polygenic topology was shown to best fit the information contained in the sequences. However, the taxonomic and phylogenetic information provided by the three markers separately was also valid. Therefore, either of the functional markers (amoA or amoB) can be used to trace ammonia oxidizers in environmental studies in which only one gene can be targeted. [Abstract/Link to Full Text]

Esparza J
The global HIV vaccine enterprise.
Int Microbiol. 2005 Jun;8(2):93-101.
AIDS, which twenty-five years ago no one even knew it existed, has become the most serious infectious disease worldwide. The development of an HIV vaccine is one of the most difficult challenges that modern biomedical science is confronting. To address this challenge, scientists may need to organize themselves in a more intense, targeted, and collaborative effort, such as the one proposed by the Global HIV/AIDS Vaccine Enterprise. The enterprise concept proposes to complement the creativity of individual investigators with a collaborative system that ensures a more effective use of human and financial resources to produce new scientific knowledge. It also implies that the scientific knowledge can be harnessed in a targeted way to develop practical solutions to urgent global health problems, including explicit product development activities. Different modalities of the enterprise concept are being explored for the development of drugs to treat tuberculosis and vaccines to prevent malaria. [Abstract/Link to Full Text]

Baquero F
Evolution and the nature of time.
Int Microbiol. 2005 Jun;8(2):81-91.
The concept of time is critical in evolutionary thought, but rarely has it been considered as an object of theoretical research by evolutionary biologists. Evolution is an organism's possibility of access to the future; in other words, evolutionary reward is paid out as increased time. Replicating entities are granted time, but for them, time only serves to allow replication and evolution, and to further expand the frontier of time. The present review discusses the possible influence of considering time not as a pure dimension (or an a priori intuitive condition of human experience) but as an object in itself. At least as a metaphor, time can be considered as a self-replicating entity rooted in physical (including biological) beings, with the result of producing dimensional time. Time self-replication forces beings to replicate, which, in turn, further sustains the replication of time. In that sense, time-replication may constitute the driving force, i.e., the basic engine, providing directional energy to the evolutionary process. The philosophical roots, caveats, and perspectives of this hypothesis are presented here. The metaphor of replicating-time plays with the possibility of viewing time not as a merely regulatory component of scientific inquiry but instead, as a real and creative constituent of nature and, for this reason, an object worthy of research in the natural sciences. [Abstract/Link to Full Text]

Orús P, Leranoz S
Current trends in cosmetic microbiology.
Int Microbiol. 2005 Jun;8(2):77-9. [Abstract/Link to Full Text]

Guerrero R
Joan Oro (1923-2004).
Int Microbiol. 2005 Mar;8(1):63-8. [Abstract/Link to Full Text]

Vericat JA
REACH in industrial platforms. The role of microbiologists.
Int Microbiol. 2005 Mar;8(1):59-62. [Abstract/Link to Full Text]

Veiga-Crespo P, Blasco L, Rosa-Dos-Santos F, Poza M, Villa TG
Influence of culture conditions of Gordonia jacobaea MV-26 on canthaxanthin production.
Int Microbiol. 2005 Mar;8(1):55-8.
Commercial interest in the use of natural pigments isolated from microorganisms has increased in recent years; hence, molecules belonging to the polyisoprenoid group (i.e. beta-carotene, astaxanthin, and canthaxanthin) have been the focus of much attention. The bacterium Gordonia jacobaea readily synthesizes and accumulates large amounts of canthaxanthin (beta-beta'-carotene-4,4'-dione), which is widely used in the food and cosmetics industries. In the present work, the effects of different low-cost raw materials on fermentation and canthaxanthin accumulation by a hyperpigmented strain of G. jacobaea were studied. Canthaxanthin production and peak levels of accumulation varied according to the different media used. [Abstract/Link to Full Text]

Ramazotti-Ferrati A, Tavolaro P, Destro MT, Landgraf M, Franco BD
A comparison of ready-to-use systems for evaluating the microbiological quality of acidic fruit juices using non-pasteurized orange juice as an experimental model.
Int Microbiol. 2005 Mar;8(1):48-53.
Several alternative analytical methods are currently available for the rapid microbiological testing of food. Due to their many advantages, particularly their convenience of use, the popularity of ready-to-use systems for the enumeration of hygiene indicator microorganisms is increasing. However, the ability of these systems to enumerate stressed microorganisms, such as those that may be found growing in acidic foods, is unknown. Therefore, the aim of this study was to evaluate the performance of Petrifilm(tm) and SimPlate(tm) plates for the enumeration of total aerobes and fungi (yeasts and molds) in acidic fruit juices, using non-pasteurized orange juice as an experimental model. The samples were analyzed before and after neutralization of pH, and the results were compared with those obtained using conventional procedures, i.e. pour-plates containing Standard Methods Agar, acidified potato dextrose agar, or dichloran-glycerol agar. The results obtained with Petrifilm and SimPlate for counts of mesophilic aerobes as well as for yeast and mold correlated well with those obtained using conventional procedures. Although no statistically significant differences were observed between counts of non-neutralized and neutralized samples (alpha >/== 0.05), better correlation indexes were observed in the neutralized samples. Both Petrifilm and SimPlate proved to be good alternative methods for testing the microbiological quality of acidic fruit juices. [Abstract/Link to Full Text]

Matsuki S, Ozaki E, Shozu M, Inoue M, Shimizu S, Yamaguchi N, Karasawa T, Yamagishi T, Nakamura S
Colonization by Clostridium difficile of neonates in a hospital, and infants and children in three day-care facilities of Kanazawa, Japan.
Int Microbiol. 2005 Mar;8(1):43-8.
The intestinal-carriage rates of Clostridium difficile in neonates hospitalized in the University Hospital's Center for Perinatal and Reproductive Health and in infants and children enrolled in two day-nurseries and a kindergarten were examined. Swab samples from the floors of these facilities were also analyzed to determine the extent of environmental contamination by this organism. C. difficile was found in the stool of only one of 40 neonates during the normal 1-week stay in the hospital after delivery. The isolate from the neonate was identical to that of her mother, as determined by PCR ribotyping, pulsed-field gel electrophoresis analysis, and toxin gene type, suggesting that the C. difficile-positive neonate acquired the organism from her mother rather than from the environment. By contrast, 47 (48.0%) of the 98 infants and children, comprising 50 enrolled in two day-nurseries who were >= 3 years old and 48 enrolled in a kindergarten who were 2-5 years old, carried C. difficile. The carriage rate in infants under 2 years of age was much higher (84.4%) than in children 2 years old and older (30.3%). When analyzed according to age group, the carriage rates were 100, 75.0, 45.5, 24.0, 38.5, and 23.5% in infants and children 0, 1, 2, 3, 4, and 5 years old, respectively. The observation that several children were colonized with the same type of C. difficile strain in each day-care facility, and that the floors of day-nursery A and kindergarten C were contaminated with C. difficile strains identical to those colonizing the intestines of children enrolled in those facilities suggests that cross-infection of C. difficile among children occurs through C. difficile-carrying children or their contaminated environments. [Abstract/Link to Full Text]

Jimenez J, Castelao BA, Gonzalez-Novo A, Sanchez-Perez M
The role of MEN (mitosis exit network) proteins in the cytokinesis of Saccharomyces cerevisiae.
Int Microbiol. 2005 Mar;8(1):33-42.
At the latest stages of their cell cycle, cells carry out crucial processes for the correct segregation of their genetic and cytoplasmic material. In this work, we provide evidence demonstrating that the cell cycle arrest of some MEN (mitosis exit network) mutants in the anaphase-telophase transition is bypassed. In addition, the ability of cdc15 diploid mutant strains to develop non-septated chains of cells, supported by nuclear division, is shown. This phenotype is also displayed by haploid cdc15 mutant strains when cell lysis is prevented by osmotic protection, and shared by other MEN mutants. By contrast, anaphase-telophase arrest is strictly observed in double MEN-FEAR (fourteen early anaphase release) mutants. In this context, the overexpression of a FEAR component, SPO12, in a MEN mutant background enhances the ability of MEN mutants to bypass cell cycle arrest. Taken together, these data suggest a critical role of Cdc15 and other MEN proteins in cytokinesis, allowing a new model for their cellular function to be proposed. [Abstract/Link to Full Text]

Peretó J
Controversies on the origin of life.
Int Microbiol. 2005 Mar;8(1):23-31.
Different viewpoints, many with deep philosophical and historical roots, have shaped the scientific study of the origin of life. Some of these argue that primeval life was based on simple anaerobic microorganisms able to use a wide inventory of abiotic organic materials (i.e. a heterotrophic origin), whereas others invoke a more sophisticated organization, one that thrived on simple inorganic molecules (i.e. an autotrophic origin). While many scientists assume that life started as a self-replicative molecule, the first gene, a primitive self-catalytic metabolic network has also been proposed as a starting point. Even the emergence of the cell itself is a contentious issue: did boundaries and compartments appear early or late during life's origin? Starting with a recent definition of life, based on concepts of autonomy and open-ended evolution, it is proposed here that, firstly, organic molecules self-organized in a primordial metabolism located inside protocells. The flow of matter and energy across those early molecular systems allowed the generation of more ordered states, forming the cradle of the first genetic records. Thus, the origin of life was a process initiated within ecologically interconnected autonomous compartments that evolved into cells with hereditary and true Darwinian evolutionary capabilities. In other words, the individual existence of life preceded its historical-collective dimension. [Abstract/Link to Full Text]

Arias ME, Gonzalez-Perez JA, Gonzalez-Vila FJ, Ball AS
Soil health -- a new challenge for microbiologists and chemists.
Int Microbiol. 2005 Mar;8(1):13-21.
Soil health refers to the biological, chemical, and physical features of soil that are essential to long-term, sustainable agricultural productivity with minimal environmental impact. Thus, soil health provides an overall picture of soil functionality. Although it cannot be measured directly, soil health can be inferred by measuring specific soil properties (e.g. organic matter content) and by observing soil status (e.g. fertility). There is also increased interest in studying soil microorganisms in their particular environments, as microbial diversity is intimately related to soil structure and function. One of the key objectives in determining soil health is to acquire indicators that can be used to evaluate the soil's current status and hence to develop sustainable agricultural systems. In this regard, significant progress has been made over the last few years in the development of specific biomarkers and macromolecular probes, enabling rapid and reliable measurements of soil microbial communities. In addition, modern molecular biological techniques, such as fluorescence in situ hybridization (FISH), reverse transcriptase polymerase chain reaction (RT-PCR), denaturing gradient gel electrophoresis (DGGE), and terminal restriction fragment length polymorphism (T-RFLP), have facilitated the analysis of microbial biodiversity and activity, whereas the application of modern analytical techniques, such as nuclear magnetic resonance (NMR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), have provided data on soil chemistry. The combination of these two approaches offers promise in determining soil health status. [Abstract/Link to Full Text]

Llorca J
Organic matter in comets and cometary dust.
Int Microbiol. 2005 Mar;8(1):5-12.
Comets are primitive conglomerates of the solar system containing a mixture of frozen gases, refractory grains, and carbonaceous particles rich in biogenic elements. The dramatic display of comets is mostly caused by a cloud of micrometer-sized dust particles that leave the comet nucleus when frozen gases sublimate as they approach the Sun. Analyses of cometary dust captured in the stratosphere together with data obtained from space missions to comets have revealed the presence of a great variety of organic molecules. Since substantial amounts of cometary dust were gently deposited on Earth, their organic content could have played a major role in prebiotic processes prior to the appearance of microorganisms. This review discusses the description and implications for life of the organic content of comets and cometary dust. [Abstract/Link to Full Text]

Salicrup LA, Rohrbaugh ML
Partnerships in technology transfer. An innovative program to enhance biomedical research and global health.
Int Microbiol. 2005 Mar;8(1):1-3. [Abstract/Link to Full Text]

Colwell RR
Infectious disease and environment: cholera as a paradigm for waterborne disease.
Int Microbiol. 2004 Dec;7(4):285-9. [Abstract/Link to Full Text]

Bernardo D, Pérez Cabo A, Novaes-Ledieu M, Pardo J, García Mendoza C
Comparative effect of the fungicide Prochloraz-Mn on Agaricus bisporus vegetative-mycelium and fruit-body cell walls.
Int Microbiol. 2004 Dec;7(4):277-81.
Fungicides to control mycopathogens of commercial Agaricus bisporus, a mushroom cultivated for human consumption, are a major field of study, since these chemicals are toxic to both the host and its fungal parasites. The fungicide Prochloraz-Mn, used at its LD50 for A. bisporus, partially inhibited protein biosynthesis in the vegetative mycelial cell walls of this mushroom and caused significant changes in cell-wall polysaccharide structure, as deduced by methylation analysis and gas liquid chromatography-mass spectrometry (GLC-MS). Furthermore, the aggregated mycelial walls showed distinct alterations in their overall chemical composition following the administration of Prochloraz-Mn at the LD50 and the LD50 x1000. As expected, GLC-MS studies indicated that the latter dose caused more appreciable differences in polysaccharide structure. The decrease in mushroom crop yields obtained from industrial cultures treated with Prochloraz-Mn to control V. fungicola infection depended on the dose of the fungicide employed, whereas fruit-body morphology was only slightly affected at the highest Prochloraz-Mn concentration used. [Abstract/Link to Full Text]

Blanco M, Padola NL, Krüger A, Sanz ME, Blanco JE, González EA, Dahbi G, Mora A, Bernárdez MI, Etcheverría AI, Arroyo GH, Lucchesi PM, Parma AE, Blanco J
Virulence genes and intimin types of Shiga-toxin-producing Escherichia coli isolated from cattle and beef products in Argentina.
Int Microbiol. 2004 Dec;7(4):269-76.
A total of 153 Shiga-toxin-producing Escherichia coli (STEC) isolates from feces of cattle and beef products (hamburgers and ground beef) in Argentina were characterized in this study. PCR showed that 22 (14%) isolates carried stx1 genes, 113 (74%) possessed stx2 genes and 18 (12%) both stx1 and stx2. Intimin (eae), enterohemolysin (ehxA), and STEC autoagglutinating adhesin (saa) virulence genes were detected in 36 (24%), 70 (46%) and in 34 (22%) of the isolates, respectively. None of 34 saa-positive isolates carried the gene eae, and 31 were ehxA-positive. Fourteen (7 of serotype O26:H11 and 4 of serotype O5:H-) isolates had intimin b1, 16 isolates possessed intimin g1 (11 of serotype O145:H- and 5 of serotype O157:H7), 5 isolates had intimin type e1 (4 of serotypes O103:H- and O103:H2), and one isolate O111:H- showed intimin type q/g2. Although the 153 STEC isolates belonged to 63 different seropathotypes, only 12 accounted for 58% of isolates. Seropathotype ONT:H- stx2 (18 isolates) was the most common, followed by O171:H2 stx2 (12 isolates), etc. The majority (84%) of STEC isolates belonged to serotypes previously found in human STEC and 56% to serotypes associated with STEC isolated from patients with hemolytic uremic syndrome (HUS). Thus, this study confirms that cattle are a major reservoir of STEC pathogenic for humans. To our knowledge, this is the first study that described the presence of saa gene in STEC of serotypes O20:H19, O39:H49, O74:H28, O79:H19, O116:H21, O120:H19, O141:H7, O141:H8, O174:H21, and ONT:H21. The serotypes O120:H19 and O185:H7 were not previously reported in bovine STEC. [Abstract/Link to Full Text]

Martínez J, Martínez L, Rosenblueth M, Silva J, Martínez-Romero E
How are gene sequence analyses modifying bacterial taxonomy? The case of Klebsiella.
Int Microbiol. 2004 Dec;7(4):261-8.
Bacterial names are continually being changed in order to more adequately describe natural groups (the units of microbial diversity) and their relationships. The problems in Klebsiella taxonomy are illustrative and common to other bacterial genera. Like other bacteria, Klebsiella spp. were isolated long ago, when methods to identify and classify bacteria were limited. However, recently developed molecular approaches have led to taxonomical revisions in several cases or to sound proposals of novel species. [Abstract/Link to Full Text]


Recent Articles in Retrovirology

Woolaway K, Asai K, Emili A, Cochrane A
hnRNP E1 and E2 have distinct roles in modulating HIV-1 gene expression.
Retrovirology. 2007;428.
Pre-mRNA processing, including 5' end capping, splicing, and 3' end cleavage/polyadenylation, are events coordinated by transcription that can influence the subsequent export and translation of mRNAs. Coordination of RNA processing is crucial in retroviruses such as HIV-1, where inefficient splicing and the export of intron-containing RNAs are required for expression of the full complement of viral proteins. RNA processing can be affected by both viral and cellular proteins, and in this study we demonstrate that a member of the hnRNP E family of proteins can modulate HIV-1 RNA metabolism and expression. We show that hnRNP E1/E2 are able to interact with the ESS3a element of the bipartite ESS in tat/rev exon 3 of HIV-1 and that modulation of hnRNP E1 expression alters HIV-1 structural protein synthesis. Overexpression of hnRNP E1 leads to a reduction in Rev, achieved in part through a decrease in rev mRNA levels. However, the reduction in Rev levels cannot fully account for the effect of hnRNP E1, suggesting that hmRNP E1 might also act to suppress viral RNA translation. Deletion mutagenesis determined that the C-terminal end of hnRNP E1 was required for the reduction in Rev expression and that replacing this portion of hnRNP E1 with that of hnRNP E2, despite the high degree of conservation, could not rescue the loss of function. [Abstract/Link to Full Text]

Lum AM, Wang BB, Li L, Channa N, Bartha G, Wabl M
Retroviral activation of the mir-106a microRNA cistron in T lymphoma.
Retrovirology. 2007;45.
Retroviral insertion into a host genome is a powerful tool not only for the discovery of cancer genes, but also for the discovery of potential oncogenic noncoding RNAs. In a large-scale mouse T lymphocyte tumor screen we found a high density of integrations upstream of the mir-106a microRNA cistron. In tumors containing an integration, the primary transcript encoding the mir-106a cistron was overexpressed five to 20-fold compared with that of control tumors; concomitantly, the mature mir-106a and mir-363 microRNAs were highly overexpressed as well. These findings suggest the mir-106a cistron plays an important role in T cell tumorigenesis. [Abstract/Link to Full Text]

Afonso PV, Zamborlini A, Saïb A, Mahieux R
Centrosome and retroviruses: the dangerous liaisons.
Retrovirology. 2007;427.
Centrosomes are the major microtubule organizing structures in vertebrate cells. They localize in close proximity to the nucleus for the duration of interphase and play major roles in numerous cell functions. Consequently, any deficiency in centrosome function or number may lead to genetic instability. Several viruses including retroviruses such as, Foamy Virus, HIV-1, JSRV, M-PMV and HTLV-1 have been shown to hamper centrosome functions for their own profit, but the outcomes are very different. Foamy viruses, HIV-1, JSRV, M-PMV and HTLV-1 use the cellular machinery to traffic towards the centrosome during early and/or late stages of the infection. In addition HIV-1 Vpr protein alters the cell-cycle regulation by hijacking centrosome functions. Enthrallingly, HTLV-1 Tax expression also targets the functions of the centrosome, and this event is correlated with centrosome amplification, aneuploidy and transformation. [Abstract/Link to Full Text]

Kumar A
The silent defense: micro-RNA directed defense against HIV-1 replication.
Retrovirology. 2007;426.
MicroRNAs play critical role in regulating gene expression. MicroRNA profile of particular cell type bears the signature of cell type specific gene expression. Given that viral pathogens replicate by evading host defenses, research is now focused on the miRNA-regulated genes that critically regulate HIV-1 propagation in human host cells. [Abstract/Link to Full Text]

Van Rompay KK, Johnson JA, Blackwood EJ, Singh RP, Lipscomb J, Matthews TB, Marthas ML, Pedersen NC, Bischofberger N, Heneine W, North TW
Sequential emergence and clinical implications of viral mutants with K70E and K65R mutation in reverse transcriptase during prolonged tenofovir monotherapy in rhesus macaques with chronic RT-SHIV infection.
Retrovirology. 2007;425.
BACKGROUND: We reported previously on the emergence and clinical implications of simian immunodeficiency virus (SIVmac251) mutants with a K65R mutation in reverse transcriptase (RT), and the role of CD8+ cell-mediated immune responses in suppressing viremia during tenofovir therapy. Because of significant sequence differences between SIV and HIV-1 RT that affect drug susceptibilities and mutational patterns, it is unclear to what extent findings with SIV can be extrapolated to HIV-1 RT. Accordingly, to model HIV-1 RT responses, 12 macaques were inoculated with RT-SHIV, a chimeric SIV containing HIV-1 RT, and started on prolonged tenofovir therapy 5 months later. RESULTS: The early virologic response to tenofovir correlated with baseline viral RNA levels and expression of the MHC class I allele Mamu-A*01. For all animals, sensitive real-time PCR assays detected the transient emergence of K70E RT mutants within 4 weeks of therapy, which were then replaced by K65R mutants within 12 weeks of therapy. For most animals, the occurrence of these mutations preceded a partial rebound of plasma viremia to levels that remained on average 10-fold below baseline values. One animal eventually suppressed K65R viremia to undetectable levels for more than 4 years; sequential experiments using CD8+ cell depletion and tenofovir interruption demonstrated that both CD8+ cells and continued tenofovir therapy were required for sustained suppression of viremia. CONCLUSION: This is the first evidence that tenofovir therapy can select directly for K70E viral mutants in vivo. The observations on the clinical implications of the K65R RT-SHIV mutants were consistent with those of SIVmac251, and suggest that for persons infected with K65R HIV-1 both immune-mediated and drug-dependent antiviral activities play a role in controlling viremia. These findings suggest also that even in the presence of K65R virus, continuation of tenofovir treatment as part of HAART may be beneficial, particularly when assisted by antiviral immune responses. [Abstract/Link to Full Text]

Rose NJ, Lever AM
Rapamycin-induced inhibition of HTLV-I LTR activity is rescued by c-Myb.
Retrovirology. 2007;424.
BACKGROUND: Rapamycin is an immunosuppressive which represses translation of transcripts harbouring a polypyrimidine motif downstream of the mRNA cap site through the mammalian target of rapamycin complex. It inhibits the abnormal autologous proliferation of T-cell clones containing a transcriptionally active human T-lymphotropic virus, type I (HTLV-I) provirus, generated from infected subjects. We showed previously that this effect is independent of the polypyrimidine motifs in the viral long terminal repeat (LTR) R region suggesting that HTLV-I transcription, and not translation, is being affected. Here we studied whether rapamycin is having an effect on a specific transcription factor pathway. Further, we investigated whether mRNAs encoding transcription factors involved in HTLV-I transcriptional activation, specifically CREB, Ets and c-Myb, are implicated in the rapamycin-sensitivity of the HTLV-I LTR. RESULTS: An in vitro analysis of the role of SRE- and NF-kappaB-mediated transcription highlighted the latter as rapamycin sensitive. Over-expression of c-Myb reversed the rapamycin effect. CONCLUSION: The sensitivity of HTLV-I transcription to rapamycin may be effected through an NF-kappaB-pathway associated with the rapamycin-sensitive mTORC1 cellular signalling network. [Abstract/Link to Full Text]

Rai MA, Warraich HJ, Ali SH, Nerurkar VR
HIV/AIDS in Pakistan: the battle begins.
Retrovirology. 2007;422.
Pakistan, the second most populous Muslim nation in the world, has started to finally experience and confront the HIV/AIDS epidemic. The country had been relatively safe from any indigenous HIV cases for around two decades, with most of the infections being attributable to deported HIV positive migrants from the Gulf States. However, the virus finally seems to have found a home-base, as evidenced by the recent HIV outbreaks among the injection drug user community. Extremely high-risk behavior has also been documented among Hijras (sex workers) and long-distance truck drivers. The weak government response coupled with the extremely distressing social demographics of this South-Asian republic also helps to compound the problem. The time is ripe now to prepare in advance, to take the appropriate measures to curtail further spread of the disease. If this opportunity is not utilized right now, little if at all could be done later. [Abstract/Link to Full Text]

Savarino A
In-Silico docking of HIV-1 integrase inhibitors reveals a novel drug type acting on an enzyme/DNA reaction intermediate.
Retrovirology. 2007;421.
BACKGROUND: HIV-1 integrase (IN) is an emerging drug target, as IN strand transfer inhibitors (INSTIs) are proving potent antiretroviral agents in clinical trials. One credible theory sees INSTIs as docking at the cellular (acceptor) DNA-binding site after IN forms a transitional complex with viral (donor) DNA. However, mapping of the DNA and INSTI binding sites within the IN catalytic core domain (CCD) has been uncertain. METHODS: Structural superimpositions were conducted using the SWISS PDB and Cn3D free software. Docking simulations of INSTIs were run by a widely validated genetic algorithm (GOLD). RESULTS: Structural superimpositions suggested that a two-metal model for HIV-1 IN CCD in complex with small molecule, 1-(5-chloroindol-3-yl)-3-(tetrazoyl)-1,3-propandione-ene (5CITEP) could be used as a surrogate for an IN/viral DNA complex, because it allowed replication of contacts documented biochemically in viral DNA/IN complexes or displayed by a crystal structure of the IN-related enzyme Tn5 transposase in complex with transposable DNA. Docking simulations showed that the fitness of different compounds for the catalytic cavity of the IN/5CITEP complex significantly (P < 0.01) correlated with their 50% inhibitory concentrations (IC50s) in strand transfer assays in vitro. The amino acids involved in inhibitor binding matched those involved in drug resistance. Both metal binding and occupation of the putative viral DNA binding site by 5CITEP appeared to be important for optimal drug/ligand interactions. The docking site of INSTIs appeared to overlap with a putative acceptor DNA binding region adjacent to but distinct from the putative donor DNA binding site, and homologous to the nucleic acid binding site of RNAse H. Of note, some INSTIs such as 4,5-dihydroxypyrimidine carboxamides/N-Alkyl-5-hydroxypyrimidinone carboxamides, a highly promising drug class including raltegravir/MK-0518 (now in clinical trials), displayed interactions with IN reminiscent of those displayed by fungal molecules from Fusarium sp., shown in the 1990s to inhibit HIV-1 integration. CONCLUSION: The 3D model presented here supports the idea that INSTIs dock at the putative acceptor DNA-binding site in a IN/viral DNA complex. This mechanism of enzyme inhibition, likely to be exploited by some natural products, might disclose future strategies for inhibition of nucleic acid-manipulating enzymes. [Abstract/Link to Full Text]

Jin X, Wu H, Smith H
APOBEC3G levels predict rates of progression to AIDS.
Retrovirology. 2007;420.
BACKGROUND: APOBEC3G (hA3G) is a newly discovered cellular factor of innate immunity that inhibits HIV replication in vitro. Whether hA3G confers protection against HIV in vivo is not known. To investigate the possible anti-HIV activity of hA3G in vivo, we examined hA3G mRNA abundance in primary human cells isolated from either HIV-infected or HIV-uninfected individuals, and found that hA3G mRNA levels follow a hierarchical order of long-term nonprogressors>HIV-uninfected>Progressors; and, hA3G mRNA abundance is correlated with surrogates of HIV disease progression: viral load and CD4 count. Another group later confirmed that HIV-infected subjects have lower hA3G mRNA levels than HIV-uninfected controls, but did not find correlations between hA3G mRNA levels and viral load or CD4 count. These conflicting results indicate that a more comprehensive, conclusive investigation of hA3G expression levels in various patient cohorts is urgently needed. PRESENTATION OF THE HYPOTHESIS: For exploring whether hA3G abundance might influence HIV disease progression, we have formulated a hypothesis that includes two parts: a) in vivo, the basal hA3G mRNA expression level per PBMC is a constant--with minor physiologic fluctuations--determined by host genetic and epigenetic elements in a healthy individual; and that the basal hA3G mRNA expression levels in a population follow a Normal (or Gaussian) distribution; b) that although HIV infects randomly, it results in more rapid disease progression in those with lower hA3G mRNA levels, and slower disease progression in those with higher hA3G mRNA levels. TESTING THE HYPOTHESIS: This hypothesis could be tested by a straight forward set of experiments to compare the distribution of hA3G mRNA levels in HIV-uninfected healthy individuals and that in HIV-infected, antiretroviral therapy-naïve subjects who are at early and late stages of infection. IMPLICATION OF THE HYPOTHESIS: Testing this hypothesis will have significant implications for biomedical research. a) It will link hA3G to the mechanisms underlying slower disease progression in long-term nonprogressors. And, b) It may help to establish a new prognostic marker, the hA3G abundance measurement, for HIV-infected patients. [Abstract/Link to Full Text]

Abdurahman S, Höglund S, Höglund A, Vahlne A
Mutation in the loop C-terminal to the cyclophilin A binding site of HIV-1 capsid protein disrupts proper virus assembly and infectivity.
Retrovirology. 2007;419.
We have studied the effects associated with two single amino acid substitution mutations in HIV-1 capsid (CA), the E98A and E187G. Both amino acids are well conserved among all major HIV-1 subtypes. HIV-1 infectivity is critically dependent on proper CA cone formation and mutations in CA are lethal when they inhibit CA assembly by destabilizing the intra and/or inter molecular CA contacts, which ultimately abrogate viral replication. Glu98, which is located on a surface of a flexible cyclophilin A binding loop is not involved in any intra-molecular contacts with other CA residues. In contrast, Glu187 has extensive intra-molecular contacts with eight other CA residues. Additionally, Glu187 has been shown to form a salt-bridge with Arg18 of another N-terminal CA monomer in a N-C dimer. However, despite proper virus release, glycoprotein incorporation and Gag processing, electron microscopy analysis revealed that, in contrast to the E187G mutant, only the E98A particles had aberrant core morphology that resulted in loss of infectivity. [Abstract/Link to Full Text]


Abstracts of the International Meeting of the Institute of Human Virology, Baltimore, Maryland, USA, 17-21 November 2006.
Retrovirology. 2006;3 Suppl 1S1-109, P1-79. [Abstract/Link to Full Text]

Gillet N, Florins A, Boxus M, Burteau C, Nigro A, Vandermeers F, Balon H, Bouzar AB, Defoiche J, Burny A, Reichert M, Kettmann R, Willems L
Mechanisms of leukemogenesis induced by bovine leukemia virus: prospects for novel anti-retroviral therapies in human.
Retrovirology. 2007;418.
In 1871, the observation of yellowish nodules in the enlarged spleen of a cow was considered to be the first reported case of bovine leukemia. The etiological agent of this lymphoproliferative disease, bovine leukemia virus (BLV), belongs to the deltaretrovirus genus which also includes the related human T-lymphotropic virus type 1 (HTLV-1). This review summarizes current knowledge of this viral system, which is important as a model for leukemogenesis. Recently, the BLV model has also cast light onto novel prospects for therapies of HTLV induced diseases, for which no satisfactory treatment exists so far. [Abstract/Link to Full Text]

Cianfriglia M, Dupuis ML, Molinari A, Verdoliva A, Costi R, Galluzzo CM, Andreotti M, Cara A, Di Santo R, Palmisano L
HIV-1 integrase inhibitors are substrates for the multidrug transporter MDR1-P-glycoprotein.
Retrovirology. 2007;417.
BACKGROUND: The discovery of diketoacid-containing derivatives as inhibitors of HIV-1 Integrase (IN) (IN inhibitors, IINs) has played a major role in validating this enzyme as an important target for antiretroviral therapy. Since the in vivo efficacy depends on access of these drugs to intracellular sites where HIV-1 replicates, we determined whether the IINs are recognized by the multidrug transporter MDR1-P-glycoprotein (P-gp) thereby reducing their intracellular accumulation. To address the effect of IINs on drug transport, nine quinolonyl diketo acid (DKA) derivatives active on the HIV-1 IN strand transfer (ST) step and with EC50 ranging from 1.83 to >50 mum in cell-based assays were tested for their in vitro interaction with P-gp in the CEM-MDR cell system. IINs were investigated for the inhibition and induction of the P-gp function and expression as well as for multidrug resistance (MDR) reversing ability. RESULTS: The HIV-1 IINs act as genuine P-gp substrates by inhibiting doxorubicin efflux and inducing P-gp functional conformation changes as evaluated by the modulation of UIC2 mAb epitope. Further, IINs chemosensitize MDR cells to vinblastine and induce P-gp expression in drug sensitive revertants of CEM-MDR cells. CONCLUSION: To our knowledge, this is the first demonstration that HIV-1 IINs are P-gp substrates. This biological property may influence the absorption, distribution and elimination of these novels anti HIV-1 compounds. [Abstract/Link to Full Text]

Benko Z, Liang D, Agbottah E, Hou J, Taricani L, Young PG, Bukrinsky M, Zhao RY
Antagonistic interaction of HIV-1 Vpr with Hsf-mediated cellular heat shock response and Hsp16 in fission yeast (Schizosaccharomyces pombe).
Retrovirology. 2007;416.
BACKGROUND: Expression of the HIV-1 vpr gene in human and fission yeast cells displays multiple highly conserved activities, which include induction of cell cycle G2 arrest and cell death. We have previously characterized a yeast heat shock protein 16 (Hsp16) that suppresses the Vpr activities when it is overproduced in fission yeast. Similar suppressive effects were observed when the fission yeast hsp16 gene was overexpressed in human cells or in the context of viral infection. In this study, we further characterized molecular actions underlying the suppressive effect of Hsp16 on the Vpr activities. RESULTS: We show that the suppressive effect of Hsp16 on Vpr-dependent viral replication in proliferating T-lymphocytes is mediated through its C-terminal end. In addition, we show that Hsp16 inhibits viral infection in macrophages in a dose-dependent manner. Mechanistically, Hsp16 suppresses Vpr activities in a way that resembles the cellular heat shock response. In particular, Hsp16 activation is mediated by a heat shock factor (Hsf)-dependent mechanism. Interestingly, vpr gene expression elicits a moderate increase of endogenous Hsp16 but prevents its elevation when cells are grown under heat shock conditions that normally stimulate Hsp16 production. Similar responsive to Vpr elevation of Hsp and counteraction of this elevation by Vpr were also observed in our parallel mammalian studies. Since Hsf-mediated elevation of small Hsps occurs in all eukaryotes, this finding suggests that the anti-Vpr activity of Hsps is a conserved feature of these proteins. CONCLUSION: These data suggest that fission yeast could be used as a model to further delineate the potential dynamic and antagonistic interactions between HIV-1 Vpr and cellular heat shock responses involving Hsps. [Abstract/Link to Full Text]

Konstantinova P, ter Brake O, Haasnoot J, de Haan P, Berkhout B
Trans-inhibition of HIV-1 by a long hairpin RNA expressed within the viral genome.
Retrovirology. 2007;415.
BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) can be inhibited by means of RNA silencing or interference (RNAi) using synthetic short interfering RNAs (siRNAs) or gene constructs encoding short hairpin RNAs (shRNAs) or long hairpin RNAs (lhRNAs). The use of siRNA and shRNA as antiviral therapeutic is limited because of the emergence of viral escape mutants. This problem is theoretically prevented by intracellular expression of lhRNAs generating multiple siRNAs that target the virus simultaneously, thus reducing the chance of viral escape. However, gene constructs encoding lhRNA molecules face problems with delivery to the right cells in an infected individual. In order to solve this problem, we constructed an HIV-1 variant with a 300 bp long hairpin structure in the 3' part of the genome corresponding to the Nef gene (HIV-lhNef). RESULTS: Intriguingly, HIV-lhNef potently inhibited wild-type HIV-1 production in trans. However, HIV-lhNef demonstrated a severe production and replication defect, which we were able to solve by selecting spontaneous virus variants with truncated hairpin structures. Although these escape variants lost the ability to trans-inhibit HIV-1, they effectively outgrew the wild-type virus in competition experiments in SupT1 cells. CONCLUSION: Expression of the lhNef hairpin within the HIV-1 genome results in potent trans-inhibition of wild-type HIV-1. Although the mechanism of trans-inhibition is currently unknown, it remains of interest to study the molecular details because the observed effect is extremely potent. This may have implications for the development of virus strains to be used as live-attenuated virus vaccines. [Abstract/Link to Full Text]

Hivin P, Basbous J, Raymond F, Henaff D, Arpin-André C, Robert-Hebmann V, Barbeau B, Mesnard JM
The HBZ-SP1 isoform of human T-cell leukemia virus type I represses JunB activity by sequestration into nuclear bodies.
Retrovirology. 2007;414.
BACKGROUND: The human T-cell leukemia virus type I (HTLV-I) basic leucine-zipper factor (HBZ) has previously been shown to modulate transcriptional activity of Jun family members. The presence of a novel isoform of HBZ, termed HBZ-SP1, has recently been characterized in adult T-cell leukemia (ATL) cells and has been found to be associated with intense nuclear spots. In this study, we investigated the role of these nuclear bodies in the regulation of the transcriptional activity of JunB. RESULTS: Using fluorescence microscopy, we found that the HBZ-SP1 protein localizes to intense dots corresponding to HBZ-NBs and to nucleoli. We analyzed the relative mobility of the EGFP-HBZ-SP1 fusion protein using fluorescence recovery after photobleaching (FRAP) analysis and found that the deletion of the ZIP domain perturbs the association of the HBZ-SP1 protein to the HBZ-NBs. These data suggested that HBZ needs cellular partners, including bZIP factors, to form HBZ-NBs. Indeed, by cotransfection experiments in COS cells, we have found that the bZIP factor JunB is able to target delocalized form of HBZ (deleted in its nuclear localization subdomains) into the HBZ-NBs. We also show that the viral protein is able to entail a redistribution of JunB into the HBZ-NBs. Moreover, by transfecting HeLa cells (known to express high level of JunB) with a vector expressing HBZ-SP1, the sequestration of JunB to the HBZ-NBs inhibited its transcriptional activity. Lastly, we analyzed the nuclear distribution of HBZ-SP1 in the presence of JunD, a Jun family member known to be activated by HBZ. In this case, no NBs were detected and the HBZ-SP1 protein was diffusely distributed throughout the nucleoplasm. CONCLUSION: Our results suggest that HBZ-mediated sequestration of JunB to the HBZ-NBs may be causing the repression of JunB activity in vivo. [Abstract/Link to Full Text]

Gayle H, Wainberg MA
Impact of the 16th International Conference on AIDS: can these conferences lead to policy change?
Retrovirology. 2007;413.
This Commentary reflects on the success of the XVI International Conference on AIDS, that was held in Toronto between August 13-18, 2006. Not only was the Conference judged to have been a scientific success, it will probably also be recognized over time as having had important political impact. It is vital that scientists and policy-makers continue to be able to interact at these meetings as part of global efforts to combat the HIV epidemic. [Abstract/Link to Full Text]

Wu Y, Beddall MH, Marsh JW
Rev-dependent lentiviral expression vector.
Retrovirology. 2007;412.
BACKGROUND: HIV-responsive expression vectors are all based on the HIV promoter, the long terminal repeat (LTR). While responsive to an early HIV protein, Tat, the LTR is also responsive to cellular activation states and to the local chromatin activity where the integration has occurred. This can result in high HIV-independent activity, and has restricted the use of LTR-based reporter vectors to cloned cells, where aberrantly high expressing (HIV-negative) cells can be eliminated. Enhancements in specificity would increase opportunities for expression vector use in detection of HIV as well as in experimental gene expression in HIV-infected cells. RESULTS: We have constructed an expression vector that possesses, in addition to the Tat-responsive LTR, numerous HIV DNA sequences that include the Rev-response element and HIV splicing sites that are efficiently used in human cells. It also contains a reading frame that is removed by cellular splicing activity in the absence of HIV Rev. The vector was incorporated into a lentiviral reporter virus, permitting detection of replicating HIV in living cell populations. The activity of the vector was measured by expression of green fluorescence protein (GFP) reporter and by PCR of reporter transcript following HIV infection. The vector displayed full HIV dependency. CONCLUSION: As with the earlier developed Tat-dependent expression vectors, the Rev system described here is an exploitation of an evolved HIV process. The inclusion of Rev-dependency renders the LTR-based expression vector highly dependent on the presence of replicating HIV. The application of this vector as reported here, an HIV-dependent reporter virus, offers a novel alternative approach to existing methods, in situ PCR or HIV antigen staining, to identify HIV-positive cells. The vector permits examination of living cells, can express any gene for basic or clinical experimentation, and as a pseudo-typed lentivirus has access to most cell types and tissues. [Abstract/Link to Full Text]

Burmeister T, Schwartz S, Hummel M, Hoelzer D, Thiel E
No genetic evidence for involvement of Deltaretroviruses in adult patients with precursor and mature T-cell neoplasms.
Retrovirology. 2007;411.
BACKGROUND: The Deltaretrovirus genus comprises viruses that infect humans (HTLV), various simian species (STLV) and cattle (BLV). HTLV-I is the main causative agent in adult T-cell leukemia in endemic areas and some of the simian T-cell lymphotropic viruses have been implicated in the induction of malignant lymphomas in their hosts. BLV causes enzootic bovine leukosis in infected cattle or sheep. During the past few years several new Deltaretrovirus isolates have been described in various primate species. Two new HTLV-like viruses in humans have recently been identified and provisionally termed HTLV-III and HTLV-IV. In order to identify a broad spectrum of Deltaretroviruses by a single PCR approach we have established a novel consensus PCR based on nucleotide sequence data obtained from 42 complete virus isolates (HTLV-I/-II, STLV-I/-II/-III, BLV). The primer sequences were based on highly interspecies-conserved virus genome regions. We used this PCR to detect Deltaretroviruses in samples from adult patients with a variety of rare T-cell neoplasms in Germany. RESULTS: The sensitivity of the consensus PCR was at least between 10-2 and 10-3 with 100% specificity as demonstrated by serial dilutions of cell lines infected with either HTLV-I, HTLV-II or BLV. Fifty acute T-cell lymphoblastic leukemia (T-ALL) samples and 33 samples from patients with various rare mature T-cell neoplasms (T-PLL, Sézary syndrome and other T-NHL) were subsequently investigated. There were no cases with HTLV-I, HTLV-II or any other Deltaretroviruses. CONCLUSION: The results rule out a significant involvement of HTLV-I or HTLV-II in these disease entities and show that other related Deltaretroviruses are not likely to be involved. The newly established Deltaretrovirus PCR may be a useful tool for identifying new Deltaretroviruses. [Abstract/Link to Full Text]

Djekic UV, Morrow CD
Analysis of the replication of HIV-1 forced to use tRNAMet(i) supports a link between primer selection, translation and encapsidation.
Retrovirology. 2007;410.
BACKGROUND: Previous studies have suggested that the process of HIV-1 tRNA primer selection and encapsidation of genomic RNA might be coupled with viral translation. In order to further investigate this relationship, proviruses were constructed in which the primer-binding site (PBS) was altered to be complementary to elongator tRNAMet (tRNAMet(e)) (HXB2-Met(e)) or initiator tRNAMet (tRNAMet(i)) (HXB2-Met(i)). These tRNAMet not only differ with respect to the 3' terminal 18-nucleotides, but also with respect to interaction with host cell proteins during protein synthesis. RESULTS: Consistent with previous studies, HXB2-Met(e) were infectious and maintained this PBS following short-term in vitro culture in SupT1 cells. In contrast, transfection of HBX2-Met(i) produced reduced amounts of virus (as determined by p24) and did not establish a productive infection in SupT1 cells. The low infectivity of the virus with the PBS complementary to tRNAMet(i) was not due to differences in endogenous levels of cellular tRNAMet(i) compared to tRNAMet(e); tRNAMet(i) was also capable of being selected as the primer for reverse transcription as determined by the endogenous reverse transcription reaction. The PBS of HXB2-Met(i) contains an ATG, which could act as an upstream AUG and syphon scanning ribosomes thereby reducing initiation of translation at the authentic AUG of Gag. To investigate this possibility, a provirus with an A to G change was constructed (HXB2-Met(i)AG). Transfection of HXB2-Met(i)AG resulted in increased production of virus, similar to that for the wild type virus. In contrast to HXB2-Met(i), HXB2-Met(i)AG was able to establish a productive infection in SupT1 cells. Analysis of the PBS following replication revealed the virus favored the genome with the repaired PBS (A to G) even though tRNAMet(i) was continuously selected as the primer for reverse transcription. CONCLUSION: The results of these studies suggest that HIV-1 has access to both tRNAMet for selection as the replication primer and supports a co-ordination between primer selection, translation and encapsidation during virus replication. [Abstract/Link to Full Text]

Yedavalli VR, Jeang KT
Methylation: a regulator of HIV-1 replication?
Retrovirology. 2007;49.
Recent characterizations of methyl transferases as regulators of cellular processes have spurred investigations into how methylation events might influence the HIV-1 life cycle. Emerging evidence suggests that protein-methylation can positively and negatively regulate HIV-1 replication. How DNA- and RNA- methylation might impact HIV-1 is also discussed. [Abstract/Link to Full Text]

Gatignol A, Dubuisson J, Wainberg MA, Cohen EA, Darlix JL
New pandemics: HIV and AIDS, HCV and chronic hepatitis, influenza virus and flu.
Retrovirology. 2007;48.
New pandemics are a serious threat to the health of the entire world. They are essentially of viral origin and spread at large speed. A meeting on this topic was held in Lyon, France, within the XIXth Jacques Cartier Symposia, a series of France-Québec meetings held every year. New findings on HIV and AIDS, on HCV and chronic hepatitis, and an update on influenza virus and flu were covered during this meeting on December 4 and 5, 2006. Aspects of viral structure, virus-host interactions, antiviral defenses, drugs and vaccinations, and epidemiological aspects were discussed for HIV and HCV. Old and recent data on the flu epidemics ended this meeting. [Abstract/Link to Full Text]

Shehu-Xhilaga M, Kent S, Batten J, Ellis S, Van der Meulen J, O'Bryan M, Cameron PU, Lewin SR, Hedger MP
The testis and epididymis are productively infected by SIV and SHIV in juvenile macaques during the post-acute stage of infection.
Retrovirology. 2007;47.
BACKGROUND: Little is known about the progression and pathogenesis of HIV-1 infection within the male genital tract (MGT), particularly during the early stages of infection. RESULTS: To study HIV pathogenesis in the testis and epididymis, 12 juvenile monkeys (Macacca nemestrina, 4-4.5 years old) were infected with Simian Immunodeficiency Virus mac 251 (SIVmac251) (n = 6) or Simian/Human Immunodeficiency Virus (SHIVmn229) (n = 6). Testes and epididymides were collected and examined by light microscopy and electron microscopy, at weeks 11-13 (SHIV) and 23 (SIV) following infection. Differences were found in the maturation status of the MGT of the monkeys, ranging from prepubertal (lacking post-meiotic germ cells) to post-pubertal (having mature sperm in the epididymal duct). Variable levels of viral RNA were identified in the lymph node, epididymis and testis following infection with both SHIVmn229 and SIVmac251. Viral protein was detected via immunofluorescence histochemistry using specific antibodies to SIV (anti-gp41) and HIV-1 (capsid/p24) protein. SIV and SHIV infected macrophages, potentially dendritic cells and T cells in the testicular interstitial tissue were identified by co-localisation studies using antibodies to CD68, DC-SIGN, alphabetaTCR. Infection of spermatogonia, but not more mature spermatogenic cells, was also observed. Leukocytic infiltrates were observed within the epididymal stroma of the infected animals. CONCLUSION: These data show that the testis and epididymis of juvenile macaques are a target for SIV and SHIV during the post-acute stage of infection and represent a potential model for studying HIV-1 pathogenesis and its effect on spermatogenesis and the MGT in general. [Abstract/Link to Full Text]

Naarding MA, Baan E, Pollakis G, Paxton WA
Effect of chloroquine on reducing HIV-1 replication in vitro and the DC-SIGN mediated transfer of virus to CD4+ T-lymphocytes.
Retrovirology. 2007;46.
BACKGROUND: Chloroquine (CQ) has been shown to inhibit HIV-1 replication in vitro as well as in vivo and has been proposed to alter the glycosylation pattern of the gp120 envelope. These activities indicate that the compound can be used not only as an effective HIV-1 therapeutic agent but also as a modulator of the gp120 envelope protein structure enabling for the production of broader neutralizing Ab responses. RESULTS: We confirm here that HIV-1 replication on CD4+ T-lymphocytes can be reduced in the presence of CQ and show that the reduced replication is producer cell mediated, with viruses generated in the presence of CQ not being inhibited for subsequent infectivity and replication. By analysing the gp120 envelope protein sequences from viruses cultured long-term in the absence or presence of CQ we demonstrate variant evolution patterns. One noticeable change is the reduction in the number of potential N-linked glycosylation sites in the V3 region as well as within the 2G12 Ab binding and neutralization epitope. We also demonstrate that HIV-1 produced in the presence of CQ has a reduced capacity for transfer by Raji-DC-SIGN cells to CD4+ T-lymphocytes, indicating another means whereby virus transmission or replication may be reduced in vivo. CONCLUSION: These results indicate that CQ should be considered as an HIV-1 therapeutic agent with its influence exerted through a number of mechanisms in vivo, including modulation of the gp120 structure. [Abstract/Link to Full Text]

Yang Q, Lucas A, Son S, Chang LJ
Overlapping enhancer/promoter and transcriptional termination signals in the lentiviral long terminal repeat.
Retrovirology. 2007;44.
Oncoretrovirus, but not lentivirus, displays a high transcriptional readthrough activity in the 3' long terminal repeat (LTR) (Zaiss et al. J. Virol. 76, 7209-7219, 2002). However, the U3-deleted, self-inactivating (SIN) lentiviral LTR also exhibits high transcriptional readthrough activity. Since the canonical "core" polyadenylation signal (AAUAAA) of the lentivirus is located in the R-U5 region, the above finding suggests that additional RNA termination signals must be present in the U3 region. Insertion of alternative termination signals including panhuman T cell leukemia virus type I polyadenylation signal, a 3' end small intron, and a tertiary tRNA motif into the lentiviral SIN LTR did not restore the transcriptional termination function. Functional dissection of the U3 region revealed that 70-80% of the termination signals reside in the transcriptional control region within 124 nt overlapping NFkappaB, Sp1 and TATA binding sites. Serial deletion analysis of the transcriptional control region indicates that the lentiviral enhancer/promoter elements are essential to the RNA termination function. These results characterize the mechanism of lentiviral transcriptional readthrough, which addresses important fundamental and practical issue of RNA readthrough influencing lentiviral gene function and vector safety. [Abstract/Link to Full Text]

Goujon C, Rivière L, Jarrosson-Wuilleme L, Bernaud J, Rigal D, Darlix JL, Cimarelli A
SIVSM/HIV-2 Vpx proteins promote retroviral escape from a proteasome-dependent restriction pathway present in human dendritic cells.
Retrovirology. 2007;42.
BACKGROUND: Vpx is a non-structural protein coded by members of the SIVSM/HIV-2 lineage that is believed to have originated by duplication of the common vpr gene present in primate lentiviruses. Vpx is incorporated into virion particles and is thus present during the early steps of viral infection, where it is thought to drive nuclear import of viral nucleoprotein complexes. We have previously shown that Vpx is required for SIVMAC-derived lentiviral vectors (LVs) infection of human monocyte-derived dendritic cells (DCs). However, since the requirement for Vpx is specific for DCs and not for other non-dividing cell types, this suggests that Vpx may play a role other than nuclear import. RESULTS: Here, we show that the function of Vpx in the infection of DCs is conserved exclusively within the SIVSM/HIV-2 lineage. At a molecular level, Vpx acts by promoting the accumulation of full length viral DNA. Furthermore, when supplied in target cells prior to infection, Vpx exerts a similar effect following infection of DCs with retroviruses as divergent as primate and feline lentiviruses and gammaretroviruses. Lastly, the effect of Vpx overlaps with that of the proteasome inhibitor MG132 in DCs. CONCLUSION: Overall, our results support the notion that Vpx modifies the intracellular milieu of target DCs to facilitate lentiviral infection. The data suggest that this is achieved by promoting viral escape from a proteasome-dependent pathway especially detrimental to viral infection in DCs. [Abstract/Link to Full Text]

Heaslet H, Lin YC, Tam K, Torbett BE, Elder JH, Stout CD
Crystal structure of an FIV/HIV chimeric protease complexed with the broad-based inhibitor, TL-3.
Retrovirology. 2007;41.
We have obtained the 1.7 A crystal structure of FIV protease (PR) in which 12 critical residues around the active site have been substituted with the structurally equivalent residues of HIV PR (12X FIV PR). The chimeric PR was crystallized in complex with the broad-based inhibitor TL-3, which inhibits wild type FIV and HIV PRs, as well as 12X FIV PR and several drug-resistant HIV mutants 1234. Biochemical analyses have demonstrated that TL-3 inhibits these PRs in the order HIV PR > 12X FIV PR > FIV PR, with Ki values of 1.5 nM, 10 nM, and 41 nM, respectively 234. Comparison of the crystal structures of the TL-3 complexes of 12X FIV and wild-typeFIV PR revealed theformation of additinal van der Waals interactions between the enzyme inhibitor in the mutant PR. The 12X FIV PR retained the hydrogen bonding interactions between residues in the flap regions and active site involving the enzyme and the TL-3 inhibitor in comparison to both FIV PR and HIV PR. However, the flap regions of the 12X FIV PR more closely resemble those of HIV PR, having gained several stabilizing intra-flap interactions not present in wild type FIV PR. These findings offer a structural explanation for the observed inhibitor/substrate binding properties of the chimeric PR. [Abstract/Link to Full Text]

Jeang KT
Libya, HIV, and open communication.
Retrovirology. 2006;399.
This year-end editorial discusses several points including the recent Libyan verdict sentencing five Bulgarian nurses and a Palestinian doctor to death for allegedly infecting 426 children with HIV. It also comments on the role played by open communication for bridging cultural misunderstandings and summarizes briefly Retrovirology's progress in 2006. [Abstract/Link to Full Text]

Fleutelot E
'Libyan Trial': a verdict running counter to scientific evidence.
Retrovirology. 2006;398.
Sidaction's appeal regarding the sentencing of medical personnels in the Libyan-HIV infection cases. [Abstract/Link to Full Text]

Metzner KJ, Binley JM, Gettie A, Marx P, Nixon DF, Connor RI
Tenofovir treatment augments anti-viral immunity against drug-resistant SIV challenge in chronically infected rhesus macaques.
Retrovirology. 2006;397.
BACKGROUND: Emergence of drug-resistant strains of human immunodeficiency virus type 1 (HIV-1) is a major obstacle to successful antiretroviral therapy (ART) in HIV-infected patients. Whether antiviral immunity can augment ART by suppressing replication of drug-resistant HIV-1 in humans is not well understood, but can be explored in non-human primates infected with simian immunodeficiency virus (SIV). Rhesus macaques infected with live, attenuated SIV develop robust SIV-specific immune responses but remain viremic, often at low levels, for periods of months to years, thus providing a model in which to evaluate the contribution of antiviral immunity to drug efficacy. To investigate the extent to which SIV-specific immune responses augment suppression of drug-resistant SIV, rhesus macaques infected with live, attenuated SIVmac239Deltanef were treated with the reverse transcriptase (RT) inhibitor tenofovir, and then challenged with pathogenic SIVmac055, which has a five-fold reduced sensitivity to tenofovir. RESULTS: Replication of SIVmac055 was detected in untreated macaques infected with SIVmac239Deltanef, and in tenofovir-treated, naïve control macaques. The majority of macaques infected with SIVmac055 experienced high levels of plasma viremia, rapid CD4+ T cell loss and clinical disease progression. By comparison, macaques infected with SIVmac239Deltanef and treated with tenofovir showed no evidence of replicating SIVmac055 in plasma using allele-specific real-time PCR assays with a limit of sensitivity of 50 SIV RNA copies/ml plasma. These animals remained clinically healthy with stable CD4+ T cell counts during three years of follow-up. Both the tenofovir-treated and untreated macaques infected with SIVmac239Deltanef had antibody responses to SIV gp130 and p27 antigens and SIV-specific CD8+ T cell responses prior to SIVmac055 challenge, but only those animals receiving concurrent treatment with tenofovir resisted infection with SIVmac055. CONCLUSION: These results support the concept that anti-viral immunity acts synergistically with ART to augment drug efficacy by suppressing replication of viral variants with reduced drug sensitivity. Treatment strategies that seek to combine immunotherapeutic intervention as an adjunct to antiretroviral drugs may therefore confer added benefit by controlling replication of HIV-1, and reducing the likelihood of treatment failure due to the emergence of drug-resistant virus, thereby preserving treatment options. [Abstract/Link to Full Text]


Recent Articles in Virology Journal

Gray L, Churchill MJ, Sterjovski J, Witlox K, Learmont JC, Sullivan JS, Wesselingh SL, Gabuzda D, Cunningham AL, McPhee DA, Gorry PR
Phenotype and envelope gene diversity of nef-deleted HIV-1 isolated from long-term survivors infected from a single source.
Virol J. 2007;475.
BACKGROUND: The Sydney blood bank cohort (SBBC) of long-term survivors consists of multiple individuals infected with attenuated, nef-deleted variants of human immunodeficiency virus type 1 (HIV-1) acquired from a single source. Long-term prospective studies have demonstrated that the SBBC now comprises slow progressors (SP) as well as long-term nonprogressors (LTNP). Convergent evolution of nef sequences in SBBC SP and LTNP indicates the in vivo pathogenicity of HIV-1 in SBBC members is dictated by factors other than nef. To better understand mechanisms underlying the pathogenicity of nef-deleted HIV-1, we examined the phenotype and env sequence diversity of sequentially isolated viruses (n = 2) from 3 SBBC members. RESULTS: The viruses characterized here were isolated from two SP spanning a three or six year period during progressive HIV-1 infection (subjects D36 and C98, respectively) and from a LTNP spanning a two year period during asymptomatic, nonprogressive infection (subject C18). Both isolates from D36 were R5X4 phenotype and, compared to control HIV-1 strains, replicated to low levels in peripheral blood mononuclear cells (PBMC). In contrast, both isolates from C98 and C18 were CCR5-restricted. Both viruses isolated from C98 replicated to barely detectable levels in PBMC, whereas both viruses isolated from C18 replicated to low levels, similar to those isolated from D36. Analysis of env by V1V2 and V3 heteroduplex tracking assay, V1V2 length polymorphisms, sequencing and phylogenetic analysis showed distinct intra- and inter-patient env evolution. CONCLUSION: Independent evolution of env despite convergent evolution of nef may contribute to the in vivo pathogenicity of nef-deleted HIV-1 in SBBC members, which may not necessarily be associated with changes in replication capacity or viral coreceptor specificity. [Abstract/Link to Full Text]

Zekri AR, Hafez MM, Mohamed NI, Hassan ZK, El-Sayed MH, Khaled MM, Mansour T
Hepatitis B virus (HBV) genotypes in Egyptian pediatric cancer patients with acute and chronic active HBV infection.
Virol J. 2007;474.
BACKGROUND: There are eight genotypes of hepatitis B virus (A-H) and subgenotypes are recognized. Genotyping can be accomplished based on a partial sequence of HBV genome such as the pre-S or S gene. Several methods have been developed and used for HBV genotyping. This study was undertaken to determine the HBV genotypes in Egyptian pediatric cancer patients with acute and chronic liver disease. METHODS: HBV genotypes were determined in 22 patients who had acute forms of liver disease (AH) and in 48 patients with chronic active hepatitis (CAH). A type-specific primer based the nested-PCR method was employed in the HBV genotyping. RESULTS: This study showed that HBV infections in pediatric cancer patients are attributed predominantly to viral genotypes D and B that constituted 37.1% and 25.7%, respectively of the total infections. In addition, there was a relatively high prevalence of mixed infections of 15.7% among the studied group especially mixed A/D genotype infections. Genotype D was found significantly more often in patients with CAH than in patients with AH [23/48(47.9%) v 3/22 (13.6%)]. CONCLUSION: These findings show the distribution of HBV A-D genotypes in pediatric cancer Egyptian patients. Furthermore, our results indicate a markedly high prevalence of mixed A/D genotype infections in subjects with CAH and a possible association of mixed infections with the severity of liver diseases. [Abstract/Link to Full Text]

Yang SJ, Hruby DE
Vaccinia virus A12L protein and its AG/A proteolysis play an important role in viral morphogenic transition.
Virol J. 2007;473.
Like the major vaccinia virus (VV) core protein precursors, p4b and p25K, the 25 kDa VV A12L late gene product (p17K) is proteolytically maturated at the conserved Ala-Gly-Ala motif. However, the association of the precursor and its cleavage product with the core of mature virion suggests that both of the A12L proteins may be required for virus assembly. Here, in order to test the requirement of the A12L protein and its proteolysis in viral replication, a conditional lethal mutant virus (vvtetOA12L) was constructed to regulate A12L expression by the presence or absence of an inducer, tetracycline. In the absence of tetracycline, replication of vvtetOA12L was inhibited by 80% and this inhibition could be overcome by transient expression of the wild-type copy of the A12L gene. In contrast, mutation of the AG/A site abrogated the ability of the transfected A12L gene to rescue, indicating that A12L proteolysis plays an important role in viral replication. Electron microscopy analysis of the A12L deficient virus demonstrated the aberrant virus particles, which were displayed by the AG/A site mutation. Thus, we concluded that the not only A12L protein but also its cleavage processing plays an essential role in virus morphogenic transition. [Abstract/Link to Full Text]

Luo M, Green TJ, Zhang X, Tsao J, Qiu S
Structural comparisons of the nucleoprotein from three negative strand RNA virus families.
Virol J. 2007;472.
Structures of the nucleoprotein of three negative strand RNA virus families, borna disease virus, rhabdovirus and influenza A virus, are now available. Structural comparisons showed that the topology of the RNA binding region from the three proteins is very similar. The RNA was shown to fit into a cavity formed by the two distinct domains of the RNA binding region in the rhabdovirus nucleoprotein. Two helices connecting the two domains characterize the center of the cavity. The nucleoproteins contain at least 5 conserved helices in the N-terminal domain and 3 conserved helices in the C-terminal domain. Since all negative strand RNA viruses are required to have the ribonucleoprotein complex as their active genomic templates, it is perceivable that the (5H+3H) structure is a common motif in the nucleoprotein of negative strand RNA viruses. [Abstract/Link to Full Text]

Liu C, Day ND, Branigan PJ, Gutshall LL, Sarisky RT, Del Vecchio AM
Relationship between the loss of neutralizing antibody binding and fusion activity of the F protein of human respiratory syncytial virus.
Virol J. 2007;471.
To elucidate the relationship between resistance to HRSV neutralizing antibodies directed against the F protein and the fusion activity of the F protein, a recombinant approach was used to generate a panel of mutations in the major antigenic sites of the F protein. These mutant proteins were assayed for neutralizing mAb binding (ch101F, palivizumab, and MAb19), level of expression, post-translational processing, cell surface expression, and fusion activity. Functional analysis of the fusion activity of the panel of mutations revealed that the fusion activity of the F protein is tolerant to multiple changes in the site II and IV/V/VI region in contrast with the somewhat limited spectrum of changes in the F protein identified from the isolation of HRSV neutralizing antibody virus escape mutants. This finding suggests that aspects other than fusion activity may limit the spectrum of changes tolerated within the F protein that are selected for by neutralizing antibodies. [Abstract/Link to Full Text]

De Jesus NH
Epidemics to eradication: the modern history of poliomyelitis.
Virol J. 2007;470.
Poliomyelitis has afflicted humankind since antiquity, and for nearly a century now, we have known the causative agent, poliovirus. This pathogen is an enterovirus that in recent history has been the source of a great deal of human suffering. Although comparatively small, its genome is packed with sufficient information to make it a formidable pathogen. In the last 20 years the Global Polio Eradication Initiative has proven successful in greatly diminishing the number of cases worldwide but has encountered obstacles in its path which have made halting the transmission of wild polioviruses a practical impossibility. As we begin to realize that a change in strategy may be crucial in achieving success in this venture, it is imperative that we critically evaluate what is known about the molecular biology of this pathogen and the intricacies of its interaction with its host so that in future attempts we may better equipped to more effectively combat this important human pathogen. [Abstract/Link to Full Text]

Culley AI, Lang AS, Suttle CA
The complete genomes of three viruses assembled from shotgun libraries of marine RNA virus communities.
Virol J. 2007;469.
BACKGROUND: RNA viruses have been isolated that infect marine organisms ranging from bacteria to whales, but little is known about the composition and population structure of the in situ marine RNA virus community. In a recent study, the majority of three genomes of previously unknown positive-sense single-stranded (ss) RNA viruses were assembled from reverse-transcribed whole-genome shotgun libraries. The present contribution comparatively analyzes these genomes with respect to representative viruses from established viral taxa. RESULTS: Two of the genomes (JP-A and JP-B), appear to be polycistronic viruses in the proposed order Picornavirales that fall into a well-supported clade of marine picorna-like viruses, the characterized members of which all infect marine protists. A temporal and geographic survey indicates that the JP genomes are persistent and widespread in British Columbia waters. The third genome, SOG, encodes a putative RNA-dependent RNA polymerase (RdRp) that is related to the RdRp of viruses in the family Tombusviridae, but the remaining SOG sequence has no significant similarity to any sequences in the NCBI database. CONCLUSION: The complete genomes of these viruses permitted analyses that resulted in a more comprehensive comparison of these pathogens with established taxa. For example, in concordance with phylogenies based on the RdRp, our results support a close homology between JP-A and JP-B and RsRNAV. In contrast, although classification of the SOG genome based on the RdRp places SOG within the Tombusviridae, SOG lacks a capsid and movement protein conserved within this family and SOG is thus likely more distantly related to the Tombusivridae than the RdRp phylogeney indicates. [Abstract/Link to Full Text]

Sarmiento RE, Tirado RG, Valverde LE, Gómez-Garcia B
Kinetics of antibody-induced modulation of respiratory syncytial virus antigens in a human epithelial cell line.
Virol J. 2007;468.
BACKGROUND: The binding of viral-specific antibodies to cell-surface antigens usually results in down modulation of the antigen through redistribution of antigens into patches that subsequently may be internalized by endocytosis or may form caps that can be expelled to the extracellular space. Here, by use of confocal-laser-scanning microscopy we investigated the kinetics of the modulation of respiratory syncytial virus (RSV) antigen by RSV-specific IgG. RSV-infected human epithelial cells (HEp-2) were incubated with anti-RSV polyclonal IgG and, at various incubation times, the RSV-cell-surface-antigen-antibody complexes (RSV Ag-Abs) and intracellular viral proteins were detected by indirect immunoflourescence. RESULTS: Interaction of anti-RSV polyclonal IgG with RSV HEp-2 infected cells induced relocalization and aggregation of viral glycoproteins in the plasma membrane formed patches that subsequently produced caps or were internalized through clathrin-mediated endocytosis participation. Moreover, the concentration of cell surface RSV Ag-Abs and intracellular viral proteins showed a time dependent cyclic variation and that anti-RSV IgG protected HEp-2 cells from viral-induced death. CONCLUSION: The results from this study indicate that interaction between RSV cell surface proteins and specific viral antibodies alter the expression of viral antigens expressed on the cells surface and intracellular viral proteins; furthermore, interfere with viral induced destruction of the cell. [Abstract/Link to Full Text]

Bartlett EJ, Castaño A, Surman SR, Collins PL, Skiadopoulos MH, Murphy BR
Attenuation and efficacy of human parainfluenza virus type 1 (HPIV1) vaccine candidates containing stabilized mutations in the P/C and L genes.
Virol J. 2007;467.
BACKGROUND: Two recombinant, live attenuated human parainfluenza virus type 1 (rHPIV1) mutant viruses have been developed, using a reverse genetics system, for evaluation as potential intranasal vaccine candidates. These rHPIV1 vaccine candidates have two non-temperature sensitive (non-ts) attenuating (att) mutations primarily in the P/C gene, namely CR84GHNT553A (two point mutations used together as a set) and CDelta170 (a short deletion mutation), and two ts att mutations in the L gene, namely LY942A (a point mutation), and LDelta1710-11 (a short deletion), the last of which has not been previously described. The latter three mutations were specifically designed for increased genetic and phenotypic stability. These mutations were evaluated on the HPIV1 backbone, both individually and in combination, for attenuation, immunogenicity, and protective efficacy in African green monkeys (AGMs). RESULTS: The rHPIV1 mutant bearing the novel LDelta1710-11 mutation was highly ts and attenuated in AGMs and was immunogenic and efficacious against HPIV1 wt challenge. The rHPIV1-CR84G/Delta170HNT553ALY942A and rHPIV1-CR84G/Delta170HNT553ALDelta1710-11 vaccine candidates were highly ts, with shut-off temperatures of 38 degrees C and 35 degrees C, respectively, and were highly attenuated in AGMs. Immunization with rHPIV1-CR84G/Delta170HNT553ALY942A protected against HPIV1 wt challenge in both the upper and lower respiratory tracts. In contrast, rHPIV1-CR84G/Delta170HNT553ALDelta1710-11 was not protective in AGMs due to over-attenuation, but it is expected to replicate more efficiently and be more immunogenic in the natural human host. CONCLUSION: The rHPIV1-CR84G/Delta170HNT553ALY942A and rHPIV1-CR84G/Delta170HNT553ALDelta1710-11 vaccine candidates are clearly highly attenuated in AGMs and clinical trials are planned to address safety and immunogenicity in humans. [Abstract/Link to Full Text]

Urata S, Yokosawa H, Yasuda J
Regulation of HTLV-1 Gag budding by Vps4A, Vps4B, and AIP1/Alix.
Virol J. 2007;466.
BACKGROUND: HTLV-1 Gag protein is a matrix protein that contains the PTAP and PPPY sequences as L-domain motifs and which can be released from mammalian cells in the form of virus-like particles (VLPs). The cellular factors Tsg101 and Nedd4.1 interact with PTAP and PPPY, respectively, within the HTLV-1 Gag polyprotein. Tsg101 forms a complex with Vps28 and Vps37 (ESCRT-I complex) and plays an important role in the class E Vps pathway, which mediates protein sorting and invagination of vesicles into multivesicular bodies. Nedd4.1 is an E3 ubiquitin ligase that binds to the PPPY motif through its WW motif, but its function is still unknown. In the present study, to investigate the mechanism of HTLV-1 budding in detail, we analyzed HTLV-1 budding using dominant negative (DN) forms of the class E proteins. RESULTS: Here, we report that DN forms of Vps4A, Vps4B, and AIP1 inhibit HTLV-1 budding. CONCLUSION: These findings suggest that HTLV-1 budding utilizes the MVB pathway and that these class E proteins may be targets for prevention of mother-to-infant vertical transmission of the virus. [Abstract/Link to Full Text]

Clem AL, Sims J, Telang S, Eaton JW, Chesney J
Virus detection and identification using random multiplex (RT)-PCR with 3'-locked random primers.
Virol J. 2007;465.
BACKGROUND: PCR-based detection and identification of viruses assumes a known, relatively stable genome. Unfortunately, high mutation rates may lead to extensive changes in viral nucleic acid sequences making dedicated PCR primer use problematic. Furthermore, in bioterrorism, viral consensus sequences can be genetically modified as a countermeasure to RT-PCR and DNA chip detection. Accordingly, there is a great need for the development of rapid and universal virus detection and identification technologies. RESULTS: We report herein that viral genomic DNA or RNA can be separated from host nucleic acids in plasma by filtration and nuclease digestion, and randomly amplified in a single PCR using a mixture of primers designed to be resistant to primer-dimer amplification (5'-VVVVVVVVAA-3', V = A, G or C; 38 or 6561 primers). We have termed this novel PCR method Random Multiplex (RT)-PCR since hundreds of overlapping PCR amplifications occur simultaneously. Using this method, we have successfullydetected and partially sequenced 3 separate viruses in human plasma without using virus-specific reagents (i.e., Adenovirus Type 17, Coxsackievirus A7, and Respiratory Syncytial Virus B). The method is sensitive to ~1000 genome equivalents/ml and may represent the fastest means of detection of unknown viruses. CONCLUSION: These studies suggest that the further development of random multiplex (RT)-PCR may lead to a diagnostic assay that can universally detect viruses in donated blood products as well as in patients suffering with idiopathic disease states of possible viral etiology. [Abstract/Link to Full Text]

Ganguly T, Bandhu A, Chattoraj P, Chanda PK, Das M, Mandal NC, Sau S
Repressor of temperate mycobacteriophage L1 harbors a stable C-terminal domain and binds to different asymmetric operator DNAs with variable affinity.
Virol J. 2007;464.
BACKGROUND: Lysogenic mode of life cycle of a temperate bacteriophage is generally maintained by a protein called 'repressor'. Repressor proteins of temperate lambdoid phages bind to a few symmetric operator DNAs in order to regulate their gene expression. In contrast, repressor molecules of temperate mycobacteriophages and some other phages bind to multiple asymmetric operator DNAs. Very little is known at present about the structure-function relationship of any mycobacteriophage repressor. RESULTS: Using highly purified repressor (CI) of temperate mycobacteriophage L1, we have demonstrated here that L1 CI harbors an N-terminal domain (NTD) and a C-terminal domain (CTD) which are separated by a small hinge region. Interestingly, CTD is more compact than NTD at 25 degrees C. Both CTD and CI contain significant amount of alpha-helix at 30 degrees C but unfold partly at 42 degrees C. At nearly 200 nM concentration, both proteins form appreciable amount of dimers in solution. Additional studies reveal that CI binds to O64 and OL types of asymmetric operators of L1 with variable affinity at 25 degrees C. Interestingly, repressor-operator interaction is affected drastically at 42 degrees C. The conformational change of CI is most possibly responsible for its reduced operator binding affinity at 42 degrees C. CONCLUSION: Repressors encoded by mycobacteriophages differ significantly from the repressor proteins of lambda and related phages at functional level but at structural level they are nearly similar. [Abstract/Link to Full Text]

Alam MM, Zaidi SZ, Shaukat S, Sharif S, Angez M, Naeem A, Saleha S, Butt JA, Malik SA
Common genotypes of Hepatitis B virus prevalent in injecting drug abusers (addicts) of North West Frontier Province of Pakistan.
Virol J. 2007;463.
BACKGROUND: The epidemiological significance of Hepatitis B virus genotypes has been well established and becoming an essential concern day by day however, much little is known about the mixed infection with more than one Hepatitis B virus genotypes and their clinical relevance. METHODS: Intravenous drug abusers are considered as a major risk group for the acquisition and transmission of blood borne infections like hepatitis B, however, in Pakistan, no such data has ever been reported about the epidemiology of HBV and its genotypes in Injecting Drug Users. 250 individuals were analyzed for hepatitis B virus genotypes after prior screening with serological assay for the detection of HBsAg. RESULTS: 56 (22.4%) individuals were found positive on ELSIA for HBsAg. The genotype distribution was found to be as: genotype D, 62.5%; genotype A, 8.92% while 28.57% individuals were found to be infected with a mixture of genotype A and D. CONCLUSION: There is an urgent need of the time to develop public health care policies with special emphasis towards the control of HBV transmission through high risk groups especially Injecting Drug Users. [Abstract/Link to Full Text]

Shanmukhappa K, Kim JK, Kapil S
Role of CD151, A tetraspanin, in porcine reproductive and respiratory syndrome virus infection.
Virol J. 2007;462.
BACKGROUND: Porcine reproductive and respiratory syndrome virus (PRRSV) is a RNA virus causing respiratory and reproductive diseases in swine. The susceptibility for PRRSV varies between the different breeds of swine. In cell culture, PRRSV virus can be propagated in primary porcine alveolar macrophages and some African green monkey kidney cell lines, such as MARC-145 cells. Previous studies have shown that 3' untranslated region (UTR) RNAs of the arteriviruses play an important role in the replication of the virus through interactions with cellular proteins. To better understand the differences in the replication capability of PRRSV in different cell lines, we sought to identify the host cellular proteins interacting with PRRSV 3' UTR RNA. We constructed a cDNA library of MARC-145 cell line in lambda ZAP Express vector and screened the library with the positive sense 3' UTR RNA of PRRSV. RESULTS: We found that CD151, a host cellular protein, interacting with PRRSV 3' UTR RNA. The specificity of the interaction between CD151 and PRRSV 3' UTR RNA was examined by gel shift assay as well as North-Western hybridization. The transfection of CD151 expression clone into BHK-21 rendered these cells susceptible to PRRSV infection, and the transfection of siRNA against CD151 into MARC-145 significantly reduced the level of PRRSV infection. Also, anti-CD151 antibody treatment to MARC-145 completely blocked PRRSV infection. CONCLUSION: Based on our results, we suggest that CD151 should cooperate in PRRSV infection in vitro in MARC-145 and BHK-21 cells. [Abstract/Link to Full Text]

Kearney K, Menton J, Morgan JG
Carlow virus, a 2002 GII.4 variant Norovirus strain from Ireland.
Virol J. 2007;461.
BACKGROUND: Noroviruses are the leading cause of infectious non-bacterial gastroenteritis in Ireland (population 4 million). Due to the number of outbreaks, its massive impact on the Irish health service and its seasonality, Norovirus has gained public notoriety as The Winter Vomiting Bug. The increase in cases in Ireland in the 2002-2003 season coincided with the emergence of two new Genogroup II genotype 4 variant clusters of Norovirus worldwide. RESULTS: Little research has been done on the epidemiology or molecular biology of Norovirus strains in Ireland. In an effort to combat this discrepancy, we cloned a full length human norovirus genome as a cDNA clone (J3) which can produce full length transcripts in vitro. A polymerase mutant cDNA clone (X1), in addition to a sub genomic cDNA clone (1A) were produced for use in future work.Carlow virus (Hu/NoV/GII/Carlow/2002/Ire) genome is 7559 nts in length, excluding the 3-end poly A tail and represents the first Norovirus strain from Ireland to be sequenced. CONCLUSION: Carlow virus is a member of the Farmington Hills variant cluster of Genogroup II genotype 4 noroviruses. [Abstract/Link to Full Text]

Zhou Y, Ficzycz A, Tikoo SK
Porcine adenovirus type 3 E1B large protein downregulates the induction of IL-8.
Virol J. 2007;460.
Replication-defective (E1-E3 deleted) adenovirus vector based gene delivery results in the induction of cytokines including IL-8, which may contribute to the development of inflammatory immune responses. Like other adenoviruses, E1 + E3 deleted porcine adenovirus (PAdV) 3 induces the production of IL-8 in infected cells. In contrast, no IL-8 production could be detected in cells infected with wild-type or mutant PAdV-3s containing deletion in E1A + E3 (PAV211) or E1Bsmall + E3 (PAV212). Expression of PAdV-3 E1Blarge inhibited the NF-kappaB dependent transcription of luciferase from IL-8 promoter. Imunofluorescence and electrophoretic mobility shift assays suggested that constitutive expression of PAdV-3 E1Blarge inhibited the nuclear translocation of NF-kappaB and its subsequent binding to DNA. These results suggest that E1Blarge interacts with NF-kappaB to prevent transcription and down regulate proinflammatory cytokine IL-8 production. [Abstract/Link to Full Text]

Vrioni G, Kalogeropoulos C, Gartzonika C, Priavali E, Levidiotou S
Usefulness of Herpes Consensus PCR methodology to routine diagnostic testing for herpesviruses infections in clinical specimens.
Virol J. 2007;459.
The purposes of the study were to assess the usefulness of simultaneously amplifying herpes simplex virus 1 and 2, varicella-zoster virus, cytomegalovirus, Epstein-Barr virus and human herpesvirus 6 DNA in various clinical specimens and to analyze clinical events in patients presenting positive results. A total of 763 clinical samples obtained from 758 patients, including 115 cerebrospinal fluids, 102 aqueous fluids, 445 swabs from genital (152), oro-facial (138) and other (155) skin lesions, 96 eye swabs and 5 bronchoalveolar lavages, were tested by using the Consensus polymerase chain reaction methodology. The clinical files of the patients were consulted retrospectively. 171 of the 758 patients (22.5%) were positive for at least one of the six target viruses: herpes simplex virus 1 (n = 95), varicella-zoster virus (n = 40), herpes simplex virus 2 (n = 21), herpes simplex virus 1 plus herpes simplex virus 2 (n = 8), cytomegalovirus (n = 4), Epstein-Barr virus (n = 1), human herpesvirus 6 (n = 1), and herpes simplex virus 1 plus human herpesvirus 6 (n = 1). The Consensus methodology enabled the rapid and accurate detection of herpesviruses in various clinical specimens and provided a reliable tool in the diagnosis of herpetic infections. [Abstract/Link to Full Text]

Meyer MF, Lehmann M, Cornberg M, Wiegand J, Manns MP, Klade C, Wedemeyer H
Clearance of low levels of HCV viremia in the absence of a strong adaptive immune response.
Virol J. 2007;458.
Spontaneous clearance of hepatitis C virus (HCV) has frequently been associated with the presence of HCV-specific cellular immunity. However, there had been also reports in chimpanzees demonstrating clearance of HCV-viremia in the absence of significant levels of detectable HCV-specific cellular immune responses. We here report seven asymptomatic acute hepatitis C cases with peak HCV-RNA levels between 300 and 100,000 copies/ml who all cleared HCV-RNA spontaneously. Patients were identified by a systematic screening of 1176 consecutive new incoming offenders in a German young offender institution. Four of the seven patients never developed anti-HCV antibodies and had normal ALT levels throughout follow-up. Transient weak HCV-specific CD4+ T cell responses were detectable in five individuals which did not differ in strength and breadth from age- and sex-matched patients with chronic hepatitis C and long-term recovered patients. In contrast, HCV-specific MHC-class-I-tetramer-positive cells were found in 3 of 4 HLA-A2-positive patients. Thus, these cases highlight that clearance of low levels of HCV viremia is possible in the absence of a strong adaptive immune response which might explain the low seroconversion rate after occupational exposure to HCV. [Abstract/Link to Full Text]

DeHart JL, Zimmerman ES, Ardon O, Monteiro-Filho CM, Argañaraz ER, Planelles V
HIV-1 Vpr activates the G2 checkpoint through manipulation of the ubiquitin proteasome system.
Virol J. 2007;457.
HIV-1 Vpr is a viral accessory protein that activates ATR through the induction of DNA replication stress. ATR activation results in cell cycle arrest in G2 and induction of apoptosis. In the present study, we investigate the role of the ubiquitin/proteasome system (UPS) in the above activity of Vpr. We report that the general function of the UPS is required for Vpr to induce G2 checkpoint activation, as incubation of Vpr-expressing cells with proteasome inhibitors abolishes this effect. We further investigated in detail the specific E3 ubiquitin ligase subunits that Vpr manipulates. We found that Vpr binds to the DCAF1 subunit of a cullin 4a/DDB1 E3 ubiquitin ligase. The carboxy-terminal domain Vpr(R80A) mutant, which is able to bind DCAF1, is inactive in checkpoint activation and has dominant-negative character. In contrast, the mutation Q65R, in the leucine-rich domain of Vpr that mediates DCAF1 binding, results in an inactive Vpr devoid of dominant negative behavior. Thus, the interaction of Vpr with DCAF1 is required, but not sufficient, for Vpr to cause G2 arrest. We propose that Vpr recruits, through its carboxy terminal domain, an unknown cellular factor that is required for G2-to-M transition. Recruitment of this factor leads to its ubiquitination and degradation, resulting in failure to enter mitosis. [Abstract/Link to Full Text]

Pinnoji RC, Bedadala GR, George B, Holland TC, Hill JM, Hsia SC
Repressor element-1 silencing transcription factor/neuronal restrictive silencer factor (REST/NRSF) can regulate HSV-1 immediate-early transcription via histone modification.
Virol J. 2007;456.
BACKGROUND: During primary infection of its human host, Herpes Simplex Virus Type-1 (HSV-1) establishes latency in neurons where the viral genome is maintained in a circular form associated with nucleosomes in a chromatin configration. During latency, most viral genes are silenced, although the molecular mechanisms responsible for this are unclear. We hypothesized that neuronal factors repress HSV-1 gene expression during latency. A search of the HSV-1 DNA sequence for potential regulatory elements identified a Repressor Element-1/Neuronal Restrictive Silencer Element (RE-1/NRSE) located between HSV-1 genes ICP22 and ICP4. We predicted that the Repressor Element Silencing Transcription Factor/Neuronal Restrictive Silencer Factor (REST/NRSF) regulates expression of ICP22 and ICP4. RESULTS: Transient cotransfection indicated that REST/NRSF inhibited the activity of both promoters. In contrast, cotransfection of a mutant form of REST/NRSF encoding only the DNA-binding domain of the protein resulted in less inhibition. Stably transformed cell lines containing episomal reporter plasmids with a chromatin structure showed that REST/NRSF specifically inhibited the ICP4 promoter, but not the ICP22 promoter. REST/NRSF inhibition of the ICP4 promoter was reversed by histone deacetylase (HDAC) inhibitor Trichostatin A (TSA). Additionally, chromatin immuno-precipitation (ChIP) assays indicated that the corepressor CoREST was recruited to the proximity of ICP4 promoter and that acetylation of histone H4 was reduced in the presence of REST/NRSF. CONCLUSION: Since the ICP4 protein is a key transactivator of HSV-1 lytic cycle genes, these results suggest that REST/NRSF may have an important role in the establishment and/or maintenance of HSV-1 gene silencing during latency by targeting ICP4 expression. [Abstract/Link to Full Text]

Raaben M, Einerhand AW, Taminiau LJ, van Houdt M, Bouma J, Raatgeep RH, Büller HA, de Haan CA, Rossen JW
Cyclooxygenase activity is important for efficient replication of mouse hepatitis virus at an early stage of infection.
Virol J. 2007;455.
Cyclooxygenases (COXs) play a significant role in many different viral infections with respect to replication and pathogenesis. Here we investigated the role of COXs in the mouse hepatitis coronavirus (MHV) infection cycle. Blocking COX activity by different inhibitors or by RNA interference affected MHV infection in different cells. The COX inhibitors reduced MHV infection at a post-binding step, but early in the replication cycle. Both viral RNA and viral protein synthesis were affected with subsequent loss of progeny virus production. Thus, COX activity appears to be required for efficient MHV replication, providing a potential target for anti-coronaviral therapy. [Abstract/Link to Full Text]

Chang LY, Ali AR, Hassan SS, AbuBakar S
Human neuronal cell protein responses to Nipah virus infection.
Virol J. 2007;454.
BACKGROUND: Nipah virus (NiV), a recently discovered zoonotic virus infects and replicates in several human cell types. Its replication in human neuronal cells, however, is less efficient in comparison to other fully susceptible cells. In the present study, the SK-N-MC human neuronal cell protein response to NiV infection is examined using proteomic approaches. RESULTS: Method for separation of the NiV-infected human neuronal cell proteins using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) was established. At least 800 protein spots were resolved of which seven were unique, six were significantly up-regulated and eight were significantly down-regulated. Six of these altered proteins were identified using mass spectrometry (MS) and confirmed using MS/MS. The heterogenous nuclear ribonucleoprotein (hnRNP) F, guanine nucleotide binding protein (G protein), voltage-dependent anion channel 2 (VDAC2) and cytochrome bc1 were present in abundance in the NiV-infected SK-N-MC cells in contrast to hnRNPs H and H2 that were significantly down-regulated. CONCLUSION: Several human neuronal cell proteins that are differentially expressed following NiV infection are identified. The proteins are associated with various cellular functions and their abundance reflects their significance in the cytopathologic responses to the infection and the regulation of NiV replication. The potential importance of the ratio of hnRNP F, and hnRNPs H and H2 in regulation of NiV replication, the association of the mitochondrial protein with the cytopathologic responses to the infection and induction of apoptosis are highlighted. [Abstract/Link to Full Text]

Lauterbach H, Truong P, McGavern DB
Clearance of an immunosuppressive virus from the CNS coincides with immune reanimation and diversification.
Virol J. 2007;453.
Once a virus infection establishes persistence in the central nervous system (CNS), it is especially difficult to eliminate from this specialized compartment. Therefore, it is of the utmost importance to fully understand scenarios during which a persisting virus is ultimately purged from the CNS by the adaptive immune system. Such a scenario can be found following infection of adult mice with an immunosuppressive variant of lymphocytic choriomeningitis virus (LCMV) referred to as clone 13. In this study we demonstrate that following intravenous inoculation, clone 13 rapidly infected peripheral tissues within one week, but more slowly innundated the entire brain parenchyma over the course of a month. During the establishment of persistence, we observed that genetically tagged LCMV-specific cytotoxic T lymphocytes (CTL) progressively lost function; however, the severity of this loss in the CNS was never as substantial as that observed in the periphery. One of the most impressive features of this model system is that the peripheral T cell response eventually regains functionality at ~60-80 days post-infection, and this was associated with a rapid decline in virus from the periphery. Coincident with this "reanimation phase" was a massive influx of CD4 T and B cells into the CNS and a dramatic reduction in viral distribution. In fact, olfactory bulb neurons served as the last refuge for the persisting virus, which was ultimately purged from the CNS within 200 days post-infection. These data indicate that a functionally revived immune response can prevail over a virus that establishes widespread presence both in the periphery and brain parenchyma, and that therapeutic enhancement of an existing response could serve as an effective means to thwart long term CNS persistence. [Abstract/Link to Full Text]

Wharam SD, Hall MJ, Wilson WH
Detection of virus mRNA within infected host cells using an isothermal nucleic acid amplification assay: marine cyanophage gene expression within Synechococcus sp.
Virol J. 2007;452.
BACKGROUND: Signal-Mediated Amplification of RNA Technology (SMART) is an isothermal nucleic acid amplification technology, developed for the detection of specific target sequences, either RNA (for expression) or DNA. Cyanophages are viruses that infect cyanobacteria. Marine cyanophages are ubiquitous in the surface layers of the ocean where they infect members of the globally important genus Synechococcus. RESULTS: Here we report that the SMART assay allowed us to differentiate between infected and non-infected host cultures. Expression of the cyanophage strain S-PM2 portal vertex gene (g20) was detected from infected host Synechococcus sp. WH7803 cells. Using the SMART assay, we demonstrated that g20 mRNA peaked 240-360 minutes post-infection, allowing us to characterise this as a mid to late transcript. g20 DNA was also detected, peaking 10 hours post-infection, coinciding with the onset of host lysis. CONCLUSION: The SMART assay is based on isothermal nucleic acid amplification, allowing the detection of specific sequences of DNA or RNA. It was shown to be suitable for differentiating between virus-infected and non-infected host cultures and for the detection of virus gene expression: the first reported use of this technology for such applications. [Abstract/Link to Full Text]

Ternette N, Stefanou D, Kuate S, Uberla K, Grunwald T
Expression of RNA virus proteins by RNA polymerase II dependent expression plasmids is hindered at multiple steps.
Virol J. 2007;451.
BACKGROUND: Proteins of human and animal viruses are frequently expressed from RNA polymerase II dependent expression cassettes to study protein function and to develop gene-based vaccines. Initial attempts to express the G protein of vesicular stomatitis virus (VSV) and the F protein of respiratory syncytial virus (RSV) by eukaryotic promoters revealed restrictions at several steps of gene expression. RESULTS: Insertion of an intron flanked by exonic sequences 5'-terminal to the open reading frames (ORF) of VSV-G and RSV-F led to detectable cytoplasmic mRNA levels of both genes. While the exonic sequences were sufficient to stabilise the VSV-G mRNA, cytoplasmic mRNA levels of RSV-F were dependent on the presence of a functional intron. Cytoplasmic VSV-G mRNA levels led to readily detectable levels of VSV-G protein, whereas RSV-F protein expression remained undetectable. However, RSV-F expression was observed after mutating two of four consensus sites for polyadenylation present in the RSV-F ORF. Expression levels could be further enhanced by codon optimisation. CONCLUSION: Insufficient cytoplasmic mRNA levels and premature polyadenylation prevent expression of RSV-F by RNA polymerase II dependent expression plasmids. Since RSV replicates in the cytoplasm, the presence of premature polyadenylation sites and elements leading to nuclear instability should not interfere with RSV-F expression during virus replication. The molecular mechanisms responsible for the destabilisation of the RSV-F and VSV-G mRNAs and the different requirements for their rescue by insertion of an intron remain to be defined. [Abstract/Link to Full Text]

Tsen KT, Tsen SW, Chang CL, Hung CF, Wu TC, Kiang JG
Inactivation of viruses by coherent excitations with a low power visible femtosecond laser.
Virol J. 2007;450.
BACKGROUND: Resonant microwave absorption has been proposed in the literature to excite the vibrational states of microorganisms in an attempt to destroy them. But it is extremely difficult to transfer microwave excitation energy to the vibrational energy of microorganisms due to severe absorption of water in this spectral range. We demonstrate for the first time that, by using a visible femtosecond laser, it is effective to inactivate viruses such as bacteriophage M13 through impulsive stimulated Raman scattering. RESULTS AND DISCUSSION: By using a very low power (as low as 0.5 nj/pulse) visible femtosecond laser having a wavelength of 425 nm and a pulse width of 100 fs, we show that M13 phages were inactivated when the laser power density was greater than or equal to 50 MW/cm2. The inactivation of M13 phages was determined by plaque counts and had been found to depend on the pulse width as well as power density of the excitation laser. CONCLUSION: Our experimental findings lay down the foundation for an innovative new strategy of using a very low power visible femtosecond laser to selectively inactivate viruses and other microorganisms while leaving sensitive materials unharmed by manipulating and controlling with the femtosecond laser system. [Abstract/Link to Full Text]

Wu WW, Sun YH, Panté N
Nuclear import of influenza A viral ribonucleoprotein complexes is mediated by two nuclear localization sequences on viral nucleoprotein.
Virol J. 2007;449.
BACKGROUND: The influenza A virus replicates in the nucleus of its host cell. Thus, entry of the influenza genome into the cell nucleus is necessary for establishing infection. The genome of the influenza A virus consists of eight single-stranded, negative-sense RNA molecules, individually packed with several copies of the viral nucleoprotein (NP) into ribonucleoprotein particles (vRNPs). These vRNPs are large, rod-shaped complexes containing a core of NP, around which the RNA is helically wrapped. The vRNPs are the entities that enter the nucleus, and their nuclear import must be mediated by nuclear localization sequences (NLSs) exposed on the vRNPs. NP contains at least two putative NLSs, one at the N-terminus (NLS1) and one in the middle (NLS2) of the protein. These NP NLSs have been shown to mediate the nuclear import of recombinant NP molecules. However, it remains to be determined which NLS mediates the nuclear import of influenza vRNP complexes. RESULTS: To directly track the nuclear import of the influenza A genome, we developed an experimental assay based on digitonin-permeabilized cells and fluorescently-labeled vRNPs isolated from the influenza A virus. We used this assay to determine the contribution of the two proposed NLSs on NP to the nuclear import of influenza vRNP complexes. Peptides that mimic each of the two NLSs on NP were used to compete with vRNPs for their nuclear import receptors. In addition, antibodies against the two NP NLSs were used to block the NLSs on the vRNP complexes, and thereby inhibit vRNP nuclear import. Both peptide competition and antibody inhibition of either sequence resulted in decreased nuclear accumulation of vRNPs. The two sequences act independently of each other, as inhibition of only one of the two NLSs still resulted in significant, though diminished, nuclear import of vRNPs. Furthermore, when both sequences were blocked, vRNP nuclear import was almost completely inhibited. Antibody inhibition studies further showed that NLS1 on NP is the main contributor to the nuclear import of vRNPs. CONCLUSION: Our results demonstrate that both NLS1 and NLS2 on NP can mediate the nuclear uptake of influenza A vRNPs. [Abstract/Link to Full Text]

Dyer KD, Schellens IM, Bonville CA, Martin BV, Domachowske JB, Rosenberg HF
Efficient replication of pneumonia virus of mice (PVM) in a mouse macrophage cell line.
Virol J. 2007;448.
Pneumonia virus of mice (PVM; family Paramyxoviridae, subfamily Pneumovirinae) is a natural respiratory pathogen of rodent species and an important new model for the study of severe viral bronchiolitis and pneumonia. However, despite high virus titers typically detected in infected mouse lung tissue in vivo, cell lines used routinely for virus propagation in vitro are not highly susceptible to PVM infection. We have evaluated several rodent and primate cell lines for susceptibility to PVM infection, and detected highest virus titers from infection of the mouse monocyte-macrophage RAW 264.7 cell line. Additionally, virus replication in RAW 264.7 cells induces the synthesis and secretion of proinflammatory cytokines relevant to respiratory virus disease, including tumor necrosis factor-alpha (TNF-alpha), interferon-beta (IFN-beta), macrophage inflammatory proteins 1alpha and 1beta (MIP-1alpha and MIP-1beta) and the functional homolog of human IL-8, mouse macrophage inflammatory peptide-2 (MIP-2). Identification and characterization of a rodent cell line that supports the replication of PVM and induces the synthesis of disease-related proinflammatory mediators will facilitate studies of molecular mechanisms of viral pathogenesis that will complement and expand on findings from mouse model systems. [Abstract/Link to Full Text]

Kari I, Syrjänen S, Johansson B, Peri P, He B, Roizman B, Hukkanen V
Antisense RNA directed to the human papillomavirus type 16 E7 mRNA from herpes simplex virus type 1 derived vectors is expressed in CaSki cells and downregulates E7 mRNA.
Virol J. 2007;447.
BACKGROUND: Human papillomavirus (HPV) infection is known to be the most important etiologic factor of cervical cancer. There is no HPV specific therapy available for treatment of invasive squamous cell carcinoma of the cervix and its precursor lesions. The present study elucidates the potential to use herpes simplex virus (HSV) derived vectors for expression of antisense RNA to HPV -16 E7 oncogene. RESULTS: We have constructed replication competent, nonneuroinvasive HSV-1 vectors, deleted of the gamma134.5 gene. The vectors express RNA antisense to the first 100 nucleotides of the HPV-16 E7 gene. We assayed the ability of the antisense E7 vectors R5225 (tk-) and R5226 (tk+), to produce antisense RNA, as well as the consequent effects on E7 mRNA and protein levels in HPV-16 positive CaSki cells. Anti-E7 RNA was expressed by both constructs in a dose-dependent manner. Expression of HPV-16 E7 mRNA was downregulated effectively in CaSki cells infected with the tk- recombinant R5225 or with R5226. The tk+ recombinant R5226 was effective in downregulating E7 protein expression. CONCLUSION: We have shown that anti-E7 RNA expressed from an HSV vector could efficiently downregulate HPV-16 E7 mRNA and E7 protein expression in CaSki cells. We conclude that HSV vectors may become a useful tool for gene therapy of HPV infections. [Abstract/Link to Full Text]

Garry RF
An invitation to recent graduates: publish your dissertation/thesis background section as a review in Virology Journal.
Virol J. 2007;446.
Virology Journal will publish background sections of approved dissertations or theses as Review Articles. [Abstract/Link to Full Text]


Recent Articles in Microbial Cell Factories

Chemler JA, Yan Y, Koffas MA
Biosynthesis of isoprenoids, polyunsaturated fatty acids and flavonoids in Saccharomyces cerevisiae.
Microb Cell Fact. 2006;520.
Industrial biotechnology employs the controlled use of microorganisms for the production of synthetic chemicals or simple biomass that can further be used in a diverse array of applications that span the pharmaceutical, chemical and nutraceutical industries. Recent advances in metagenomics and in the incorporation of entire biosynthetic pathways into Saccharomyces cerevisiae have greatly expanded both the fitness and the repertoire of biochemicals that can be synthesized from this popular microorganism. Further, the availability of the S. cerevisiae entire genome sequence allows the application of systems biology approaches for improving its enormous biosynthetic potential. In this review, we will describe some of the efforts on using S. cerevisiae as a cell factory for the biosynthesis of high-value natural products that belong to the families of isoprenoids, flavonoids and long chain polyunsaturated fatty acids. As natural products are increasingly becoming the center of attention of the pharmaceutical and nutraceutical industries, the use of S. cerevisiae for their production is only expected to expand in the future, further allowing the biosynthesis of novel molecular structures with unique properties. [Abstract/Link to Full Text]

Clementschitsch F, Bayer K
Improvement of bioprocess monitoring: development of novel concepts.
Microb Cell Fact. 2006;519.
The advancement of bioprocess monitoring will play a crucial role to meet the future requirements of bioprocess technology. Major issues are the acceleration of process development to reduce the time to the market and to ensure optimal exploitation of the cell factory and further to cope with the requirements of the Process Analytical Technology initiative. Due to the enormous complexity of cellular systems and lack of appropriate sensor systems microbial production processes are still poorly understood. This holds generally true for the most microbial production processes, in particular for the recombinant protein production due to strong interaction between recombinant gene expression and host cell metabolism. Therefore, it is necessary to scrutinise the role of the different cellular compartments in the biosynthesis process in order to develop comprehensive process monitoring concepts by involving the most significant process variables and their interconnections. Although research for the development of novel sensor systems is progressing their applicability in bioprocessing is very limited with respect to on-line and in-situ measurement due to specific requirements of aseptic conditions, high number of analytes, drift, and often rather low physiological relevance. A comprehensive survey of the state of the art of bioprocess monitoring reveals that only a limited number of metabolic variables show a close correlation to the currently explored chemical/physical principles. In order to circumvent this unsatisfying situation mathematical methods are applied to uncover "hidden" information contained in the on-line data and thereby creating correlations to the multitude of highly specific biochemical off-line data. Modelling enables the continuous prediction of otherwise discrete off-line data whereby critical process states can be more easily detected. The challenging issue of this concept is to establish significant on-line and off-line data sets. In this context, online sensor systems are reviewed with respect to commercial availability in combination with the suitability of offline analytical measurement methods. In a case study, the aptitude of the concept to exploit easily available online data for prediction of complex process variables in a recombinant E. coli fed-batch cultivation aiming at the improvement of monitoring capabilities is demonstrated. In addition, the perspectives for model-based process supervision and process control are outlined. [Abstract/Link to Full Text]

Karhumaa K, Wiedemann B, Hahn-Hägerdal B, Boles E, Gorwa-Grauslund MF
Co-utilization of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains.
Microb Cell Fact. 2006;518.
BACKGROUND: Fermentation of lignocellulosic biomass is an attractive alternative for the production of bioethanol. Traditionally, the yeast Saccharomyces cerevisiae is used in industrial ethanol fermentations. However, S. cerevisiae is naturally not able to ferment the pentose sugars D-xylose and L-arabinose, which are present in high amounts in lignocellulosic raw materials. RESULTS: We describe the engineering of laboratory and industrial S. cerevisiae strains to co-ferment the pentose sugars D-xylose and L-arabinose. Introduction of a fungal xylose and a bacterial arabinose pathway resulted in strains able to grow on both pentose sugars. Introduction of a xylose pathway into an arabinose-fermenting laboratory strain resulted in nearly complete conversion of arabinose into arabitol due to the L-arabinose reductase activity of the xylose reductase. The industrial strain displayed lower arabitol yield and increased ethanol yield from xylose and arabinose. CONCLUSION: Our work demonstrates simultaneous co-utilization of xylose and arabinose in recombinant strains of S. cerevisiae. In addition, the co-utilization of arabinose together with xylose significantly reduced formation of the by-product xylitol, which contributed to improved ethanol production. [Abstract/Link to Full Text]

Cos O, Ramón R, Montesinos JL, Valero F
Operational strategies, monitoring and control of heterologous protein production in the methylotrophic yeast Pichia pastoris under different promoters: a review.
Microb Cell Fact. 2006;517.
The methylotrophic yeast Pichia pastoris has been widely reported as a suitable expression system for heterologous protein production. The use of different phenotypes under PAOX promoter, other alternative promoters, culture medium, and operational strategies with the objective to maximize either yield or productivity of the heterologous protein, but also to obtain a repetitive product batch to batch to get a robust process for the final industrial application have been reported. Medium composition, kinetics growth, fermentation operational strategies from fed-batch to continuous cultures using different phenotypes with the most common PAOX promoter and other novel promoters (GAP, FLD, ICL), the use of mixed substrates, on-line monitoring of the key fermentation parameters (methanol) and control algorithms applied to the bioprocess are reviewed and discussed in detail. [Abstract/Link to Full Text]

Bertin L, Colao MC, Ruzzi M, Marchetti L, Fava F
Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor.
Microb Cell Fact. 2006;516.
BACKGROUND: Olive mill wastewater (OMW) is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. RESULTS: The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl(-1)day(-1) of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl(-1)day(-1) of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter, enriched significantly in the biofilter throughout the treatment. CONCLUSION: The silica-bead packed bed biofilm reactor developed and characterized in this study was able to significantly decontaminate anaerobically digested OMWs. Therefore, the application of an integrated anaerobic-aerobic process resulted in an improved system for valorization and decontamination of OMWs. [Abstract/Link to Full Text]

Ferraz RM, Vera A, Arís A, Villaverde A
Insertional protein engineering for analytical molecular sensing.
Microb Cell Fact. 2006;515.
The quantitative detection of low analyte concentrations in complex samples is becoming an urgent need in biomedical, food and environmental fields. Biosensors, being hybrid devices composed by a biological receptor and a signal transducer, represent valuable alternatives to non biological analytical instruments because of the high specificity of the biomolecular recognition. The vast range of existing protein ligands enable those macromolecules to be used as efficient receptors to cover a diversity of applications. In addition, appropriate protein engineering approaches enable further improvement of the receptor functioning such as enhancing affinity or specificity in the ligand binding. Recently, several protein-only sensors are being developed, in which either both the receptor and signal transducer are parts of the same protein, or that use the whole cell where the protein is produced as transducer. In both cases, as no further chemical coupling is required, the production process is very convenient. However, protein platforms, being rather rigid, restrict the proper signal transduction that necessarily occurs through ligand-induced conformational changes. In this context, insertional protein engineering offers the possibility to develop new devices, efficiently responding to ligand interaction by dramatic conformational changes, in which the specificity and magnitude of the sensing response can be adjusted up to a convenient level for specific analyte species. In this report we will discuss the major engineering approaches taken for the designing of such instruments as well as the relevant examples of resulting protein-only biosensors. [Abstract/Link to Full Text]

Miyoshi A, Bermúdez-Humarán LG, Ribeiro LA, Le Loir Y, Oliveira SC, Langella P, Azevedo V
Heterologous expression of Brucella abortus GroEL heat-shock protein in Lactococcus lactis.
Microb Cell Fact. 2006;514.
BACKGROUND: Brucella abortus is a facultative intracellular pathogen that mainly infects cattle and humans. Current vaccines rely on live attenuated strains of B. abortus, which can revert to their pathogenic status and thus are not totally safe for use in humans. Therefore, the development of mucosal live vaccines using the food-grade lactic acid bacterium, Lactococcus lactis, as an antigen delivery vector, is an attractive alternative and a safer vaccination strategy against B. abortus. Here, we report the construction of L. lactis strains genetically modified to produce B. abortus GroEL heat-shock protein, a candidate antigen, in two cellular locations, intracellular or secreted. RESULTS: Only the secreted form of GroEL was stably produced in L. lactis, suggesting a detrimental effect of GroEL protein when intracellularly produced in this bacterium. Only trace amounts of mature GroEL were detected in the supernatant fraction of induced lactococcal cultures, and the GroEL precursor remained stacked in the cell fraction. Attempts to raise the secretion yields were made, but even when GroEL was fused to a synthetic propeptide, secretion of this antigen was not improved. CONCLUSION: We found that L. lactis is able to produce, and to secrete, a stable form of GroEL into the extracellular medium. Despite the low secretion efficiency of GroEL, which suggest that this antigen interacts with the cell envelope of L. lactis, secretion seems to be the best way to achieve both production and protein yields, regardless of cellular location. The L. lactis strain secreting GroEL has potential for in vivo immunization. [Abstract/Link to Full Text]

Cardoso PG, Macedo GC, Azevedo V, Oliveira SC
Brucella spp noncanonical LPS: structure, biosynthesis, and interaction with host immune system.
Microb Cell Fact. 2006;513.
Brucella spp. are facultative intracellular pathogens that have the ability to survive and multiply in professional and non-professional phagocytes, and cause abortion in domestic animals and undulant fever in humans. Several species are recognized within the genus Brucella and this classification is mainly based on the difference in pathogenicity and in host preference. Brucella strains may occur as either smooth or rough, expressing smooth LPS (S-LPS) or rough LPS (R-LPS) as major surface antigen. This bacterium possesses an unconventional non-endotoxic lipopolysaccharide that confers resistance to anti-microbial attacks and modulates the host immune response. The strains that are pathogenic for humans (B. abortus, B. suis, B. melitensis) carry a smooth LPS involved in the virulence of these bacteria. The LPS O-chain protects the bacteria from cellular cationic peptides, oxygen metabolites and complement-mediated lysis and it is a key molecule for Brucella survival and replication in the host. Here, we review i) Brucella LPS structure; ii) Brucella genome, iii) genes involved in LPS biosynthesis; iv) the interaction between LPS and innate immunity. [Abstract/Link to Full Text]

Mattanovich D, Borth N
Applications of cell sorting in biotechnology.
Microb Cell Fact. 2006;512.
Due to its unique capability to analyze a large number of single cells for several parameters simultaneously, flow cytometry has changed our understanding of the behavior of cells in culture and of the population dynamics even of clonal populations. The potential of this method for biotechnological research, which is based on populations of living cells, was soon appreciated. Sorting applications, however, are still less frequent than one would expect with regard to their potential. This review highlights important contributions where flow cytometric cell sorting was used for physiological research, protein engineering, cell engineering, specifically emphasizing selection of overproducing cell lines. Finally conclusions are drawn concerning the impact of cell sorting on inverse metabolic engineering and systems biology. [Abstract/Link to Full Text]

Di Toro S, Zanaroli G, Fava F
Intensification of the aerobic bioremediation of an actual site soil historically contaminated by polychlorinated biphenyls (PCBs) through bioaugmentation with a non acclimated, complex source of microorganisms.
Microb Cell Fact. 2006;511.
BACKGROUND: The biotreatability of actual-site polychlorinated biphenyl (PCB)-contaminated soils is often limited by their poor content of autochthonous pollutant-degrading microorganisms. In such cases, inoculation might be the solution for a successful bioremediation. Some pure and mixed cultures of characterized PCB degrading bacteria have been tested to this purpose. However, several failures have been recorded mostly due to the inability of inoculated microbes to compete with autochthonous microflora and to face the toxicity and the scarcity of nutrients occurring in the contaminated biotope. Complex microbial systems, such as compost or sludge, normally consisting of a large variety of robust microorganisms and essential nutrients, would have better chances to succeed in colonizing degraded contaminated soils. However, such sources of microorganisms have been poorly applied in soil bioremediation and in particular in the biotreatment of soil with PCBs. Thus, in this study the effects of Enzyveba, i.e. a consortium of non-adapted microorganisms developed from composted material, on the slurry- and solid-phase aerobic bioremediation of an actual-site, aged PCB-contaminated soil were studied. RESULTS: A slow and only partial biodegradation of low-chlorinated biphenyls, along with a moderate depletion of initial soil ecotoxicity, were observed in the not-inoculated reactors. Enzyveba significantly increased the availability and the persistence of aerobic PCB- and chlorobenzoic acid-degrading cultivable bacteria in the bioreactors, in particular during the earlier phase of treatment. It also markedly enhanced PCB-biodegradation rate and extent (from 50 to 100%) as well as the final soil detoxification, in particular under slurry-phase conditions. Taken together, data obtained suggest that Enzyveba enhanced the biotreatability of the selected soil by providing exogenous bacteria and fungi able to remove inhibitory or toxic intermediates of PCB biodegradation and/or exogenous nutrients able to sustain microorganisms in charge for PCB mineralization. CONCLUSION: Enzyveba appears a promising agent for bioaugmenting actual-site PCB-polluted soils with a native low content of indigenous specialized microflora. This not only for its positive effects on the soil biotreatability but also for its availability on the market at a relatively low cost. [Abstract/Link to Full Text]

Ferrer P
Revisiting the Cellulosimicrobium cellulans yeast-lytic beta-1,3-glucanases toolbox: a review.
Microb Cell Fact. 2006;510.
Cellulosimicrobium cellulans (also known with the synonyms Cellulomonas cellulans, Oerskovia xanthineolytica, and Arthrobacter luteus) is an actinomycete that excretes yeast cell wall lytic enzyme complexes containing endo-beta-1,3-glucanases [EC 3.2.1.39 and 3.2.1.6] as key constituents. Three genes encoding endo-beta-1,3-glucanases from two C. cellulans strains have been cloned and characterised over the past years. The betaglII and betaglIIA genes from strain DSM 10297 (also known as O. xanthineolytica LL G109) encoded proteins of 40.8 and 28.6 kDa, respectively, whereas the beta-1,3-glucanase gene from strain ATCC 21606 (also known as A. luteus 73-14) encoded a 54.5 kDa protein. Alignment of their deduced amino acid sequences reveal that betaglII and betaglIIA have catalytic domains assigned to family 16 of glycosyl hydrolases, whereas the catalytic domain from the 54.5 kDa glucanase belongs to family 64. Notably, both betaglII and the 54.5 kDa beta-1,3-glucanase are multidomain proteins, having a lectin-like C-terminal domain that has been assigned to family 13 of carbohydrate binding modules, and that confers to beta-1,3-glucanases the ability to lyse viable yeast cells. Furthermore, betaglII may also undergo posttranslational proteolytic processing of its C-terminal domain, resulting in a truncated enzyme retaining its glucanase activity but with very low yeast-lytic activity. In this review, the diversity in terms of structural and functional characteristics of the C. cellulans beta-1,3-glucanases has been compiled and compared. [Abstract/Link to Full Text]

Gabig-Ciminska M
Developing nucleic acid-based electrical detection systems.
Microb Cell Fact. 2006;59.
Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and requirements for an ideal detector suitable for nucleic acid analysis include high sensitivity and high specificity protocol that can be completed in a relatively short time offering at the same time low detection limit. Moreover, systems that can be miniaturized and automated present a significant advantage over conventional technology, especially if detection is needed in the field. Electrical system technology for nucleic acid-based detection is an enabling mode for making miniaturized to micro- and nanometer scale bio-monitoring devices via the fusion of modern micro- and nanofabrication technology and molecular biotechnology. The electrical biosensors that rely on the conversion of the Watson-Crick base-pair recognition event into a useful electrical signal are advancing rapidly, and recently are receiving much attention as a valuable tool for microbial pathogen detection. Pathogens may pose a serious threat to humans, animal and plants, thus their detection and analysis is a significant element of public health. Although different conventional methods for detection of pathogenic microorganisms and their toxins exist and are currently being applied, improvements of molecular-based detection methodologies have changed these traditional detection techniques and introduced a new era of rapid, miniaturized and automated electrical chip detection technologies into pathogen identification sector. In this review some developments and current directions in nucleic acid-based electrical detection are discussed. [Abstract/Link to Full Text]

Vasala A, Panula J, Bollók M, Illmann L, Hälsig C, Neubauer P
A new wireless system for decentralised measurement of physiological parameters from shake flasks.
Microb Cell Fact. 2006;58.
BACKGROUND: Shake flasks are widely used because of their low price and simple handling. Many researcher are, however, not aware of the physiological consequences of oxygen limitation and substrate overflow metabolism that occur in shake flasks. Availability of a wireless measuring system brings the possibilities for quality control and design of cultivation conditions. RESULTS: Here we present a new wireless solution for the measurement of pH and oxygen from shake flasks with standard sensors, which allows data transmission over a distance of more than 100 metres in laboratory environments. This new system was applied to monitoring of cultivation conditions in shake flasks. The at-time monitoring of the growth conditions became possible by simple means. Here we demonstrate that with typical protocols E. coli shake flask cultures run into severe oxygen limitation and the medium is strongly acidified. Additionally the strength of the new system is demonstrated by continuous monitoring of the oxygen level in methanol-fed Pichia pastoris shake flask cultures, which allows the optimisation of substrate feeding for preventing starvation or methanol overfeed. 40 % higher cell density was obtained by preventing starvation phases which occur in standard shake flask protocols by adding methanol when the respiration activity decreased in the cultures. CONCLUSION: The here introduced wireless system can read parallel sensor data over long distances from shake flasks that are under vigorous shaking in cultivation rooms or closed incubators. The presented technology allows centralised monitoring of decentralised targets. It is useful for the monitoring of pH and dissolved oxygen in shake flask cultures. It is not limited to standard sensors, but can be easily adopted to new types of sensors and measurement places (e.g., new sensor points in large-scale bioreactors). [Abstract/Link to Full Text]

Skorupska A, Janczarek M, Marczak M, Mazur A, Król J
Rhizobial exopolysaccharides: genetic control and symbiotic functions.
Microb Cell Fact. 2006;57.
Specific complex interactions between soil bacteria belonging to Rhizobium, Sinorhizobium, Mesorhizobium, Phylorhizobium, Bradyrhizobium and Azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. Nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. Proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosaccharides, called Nod factors that are important for induction of nodule development. Bacterial surface polysaccharides are also crucial for establishment of successful symbiosis with legumes. Sugar polymers of rhizobia are composed of a number of different polysaccharides, such as lipopolysaccharides (LPS), capsular polysaccharides (CPS or K-antigens), neutral beta-1, 2-glucans and acidic extracellular polysaccharides (EPS). Despite extensive research, the molecular function of the surface polysaccharides in symbiosis remains unclear.This review focuses on exopolysaccharides that are especially important for the invasion that leads to formation of indetermined (with persistent meristem) type of nodules on legumes such as clover, vetch, peas or alfalfa. The significance of EPS synthesis in symbiotic interactions of Rhizobium leguminosarum with clover is especially noticed. Accumulating data suggest that exopolysaccharides may be involved in invasion and nodule development, bacterial release from infection threads, bacteroid development, suppression of plant defense response and protection against plant antimicrobial compounds. Rhizobial exopolysaccharides are species-specific heteropolysaccharide polymers composed of common sugars that are substituted with non-carbohydrate residues. Synthesis of repeating units of exopolysaccharide, their modification, polymerization and export to the cell surface is controlled by clusters of genes, named exo/exs, exp or pss that are localized on rhizobial megaplasmids or chromosome. The function of these genes was identified by isolation and characterization of several mutants disabled in exopolysaccharide synthesis. The effect of exopolysaccharide deficiency on nodule development has been extensively studied. Production of exopolysaccharides is influenced by a complex network of environmental factors such as phosphate, nitrogen or sulphur. There is a strong suggestion that production of a variety of symbiotically active polysaccharides may allow rhizobial strains to adapt to changing environmental conditions and interact efficiently with legumes. [Abstract/Link to Full Text]

Varcamonti M, Arsenijevic S, Martirani L, Fusco D, Naclerio G, De Felice M
Expression of the heat shock gene clpL of Streptococcus thermophilus is induced by both heat and cold shock.
Microb Cell Fact. 2006;56.
BACKGROUND: Heat and cold shock response are normally considered as independent phenomena. A small amount of evidence suggests instead that interactions may exist between them in two Lactococcus strains. RESULTS: We show the occurrence of molecular relationships between the mechanisms of cold and heat adaptations in Streptococcus thermophilus, a lactic acid bacterium widely used in dairy fermentation, where it undergoes both types of stress. We observed that cryotolerance is increased when cells are pre-incubated at high temperature. In addition, the production of a protein, identified as ClpL, a member of the heat-shock ATPase family Clp A/B, is induced at both high and low temperature. A knock-out clpL mutant is deficient in both heat and cold tolerance. However lack of production of this protein does not abolish the positive effect of heat pre-treatment towards cryotolerance. CONCLUSION: Dual induction of ClpL by cold and heat exposure of cells and reduced tolerance to both temperature shocks in a clpL mutant indicates that the two stress responses are correlated in S. thermophilus. However this protein is not responsible by itself for cryotolerance of cells pre-treated at high temperature, indicating that ClpL is necessary for the two phenomena, but does not account by itself for the relationships between them. [Abstract/Link to Full Text]

Papagianni M
Quantification of the fractal nature of mycelial aggregation in Aspergillus niger submerged cultures.
Microb Cell Fact. 2006 Feb 13;5(1):5.
ABSTRACT: BACKGROUND: Fractal geometry estimates have proven useful in studying the growth strategies of fungi in response to different environments on soil or on agar substrates, but their use in mycelia grown submerged is still rare. In the present study, the effects of certain important fermentation parameters, such as the spore inoculum level, phosphate and manganese concentrations in the medium, on mycelial morphology of the citric acid producer Aspergillus niger were determined by fractal geometry. The value of employing fractal geometry to describe mycelial structures was examined in comparison with information from other descriptors including classic morphological parameters derived from image analysis. RESULTS: Fractal analysis of distinct morphological forms produced by fermentation conditions that influence fungal morphology and acid production, showed that the two fractal dimensions DBS (box surface dimension) and DBM (box mass dimension) are very sensitive indexes, capable of describing morphological differences. The two box-counting methods applied (one applied to the whole mass of the mycelial particles and the other applied to their surface only) enabled evaluation of fractal dimensions for mycelial particles in this analysis in the region of DBS = 1.20-1.70 and DBM = 1.20-2.70. The global structure of sufficiently branched mycelia was described by a single fractal dimension D, which did not exceed 1.30. Such simple structures are true mass fractals (DBS = DBM = D) and they could be young mycelia or dispersed forms of growth produced by very dense spore inocula (108-109 spores/ml) or by addition of manganese in the medium. Mycelial clumps and pellets were effectively discriminated by fractal analysis. Fractal dimension values were plotted together with classic morphological parameters derived from image analysis for comparisons. Their sensitivity to treatment was analogous to the sensitivity of classic morphological parameters suggesting that they could be equally used as morphological descriptors. CONCLUSIONS: Starting from a spore, the mycelium develops as a mass fractal and, depending on culture conditions, it either turns to a surface fractal or remains a mass fractal. Since fractal dimensions give a measure of the degree of complexity and the mass filling properties of an object, it may be possible that a large number of morphological parameters which contribute to the overall complexity of the particles, could be replaced by these indexes effectively. [Abstract/Link to Full Text]

Branduardi PP, Sauer MM, De Gioia LL, Zampella GG, Valli MM, Mattanovich DD, Porro DD
Lactate production yield from engineered yeasts is dependent from the host background, the lactate dehydrogenase source and the lactate export.
Microb Cell Fact. 2006 Jan 30;5(1):4.
ABSTRACT: BACKGROUND: Metabolic pathway manipulation for improving the properties and the productivity of microorganisms is becoming an established concept. For the production of important metabolites, but also for a better understanding of the fundamentals of cell biology, detailed studies are required. In this work we analysed the lactate production from metabolic engineered Saccharomyces cerevisiae cells expressing a heterologous lactate dehydrogenase (LDH) gene. The LDH gene expression in a budding yeast cell introduces a novel and alternative pathway for the NAD+ regeneration, allowing a direct reduction of the intracellular pyruvate to lactate, leading to a simultaneous accumulation of lactate and ethanol. RESULTS: Four different S. cerevisiae strains were transformed with six different wild type and one mutagenised LDH genes, in combination or not with the overexpression of a lactate transporter, obtaining yield values (grams of lactate produced per grams of glucose consumed) varying from values as low as 0,0008 till values as high as 0.52 g/g. In this respect, and at the best of our information, higher redirections of the glycolysis flux have never been obtained before without any disruption and/or limitation of the competing biochemical pathways. CONCLUSIONS: In the present work it is shown that the redirection of the pathway towards the lactate production can be strongly modulated by the genetic background of the host cell, by the source of the heterologous Ldh enzyme, by improving the biochemical properties of the Ldh enzyme as well as by modulating the export of lactate in the culture media. [Abstract/Link to Full Text]

Papagianni M, Mattey M
Morphological development of Aspergillus niger in submerged citric acid fermentation as a function of the spore inoculum level. Application of neural network and cluster analysis for characterization of mycelial morphology.
Microb Cell Fact. 2006;53.
BACKGROUND: Although the citric acid fermentation by Aspergillus niger is one of the most important industrial microbial processes and various aspects of the fermentation appear in a very large number of publications since the 1950s, the effect of the spore inoculum level on fungal morphology is a rather neglected area. The aim of the presented investigations was to quantify the effects of changing spore inoculum level on the resulting mycelial morphology and to investigate the physiology that underlines the phenomena. Batch fermentations were carried out in a stirred tank bioreactor, which were inoculated directly with spores in concentrations ranging from 10(4) to 10(9) spores per ml. Morphological features, evaluated by digital image analysis, were classified using an artificial neural network (ANN), which considered four main object types: globular and elongated pellets, clumps and free mycelial trees. The significance of the particular morphological features and their combination was determined by cluster analysis. RESULTS: Cell volume fraction analysis for the various inoculum levels tested revealed that by rising the spore inoculum level from 10(4) to 10(9) spores per ml, a clear transition from pelleted to dispersed forms occurs. Glucosamine formation and release by the mycelium appears to be related to spore inoculum level. Maximum concentrations detected in fermentations inoculated with 10(4) and 10(5) spores/ml, where pellets predominated. At much higher inoculum levels (10(8), 10(9) spores/ml), lower dissolved oxygen levels during the early fermentation phase were associated with slower ammonium ions uptakes and significantly lower glucosamine concentrations while the mycelium developed in dispersed morphologies. A big increase in the main and total hyphal lengths and branching frequency was observed in mycelial trees as inoculum levels rise from 10(4) to 10(9) spores/ml, while in aggregated forms particle sizes and their compactness decreased. CONCLUSION: The methods used in this study, allowed for the detailed quantification of the transition between the two extreme morphological forms. The impact of spore inoculum level on the detailed characteristics of the particular morphological forms produced was high. Control of mycelial morphology is often regarded as a prerequisite to ensure increased productivities in industrial applications. The research described here demonstrates that adjusting the spore inoculum level controls effectively mycelial morphology. [Abstract/Link to Full Text]

Agarwal PK
Enzymes: An integrated view of structure, dynamics and function.
Microb Cell Fact. 2006 Jan 12;5(1):2.
ABSTRACT: Microbes utilize enzymes to perform a variety of functions. Enzymes are biocatalysts working as highly efficient machines at the molecular level. In the past, enzymes have been viewed as static entities and the function has been explained on the basis of direct structural interactions between the enzyme and the substrate. A variety of experimental and computational techniques, however, continue to reveal that proteins are dynamically active machines, with various parts exhibiting internal motions at a wide range of time-scales. Increasing evidence also indicates that these internal protein motions play a role in promoting protein function such as enzyme catalysis. Moreover, the thermodynamical fluctuations of the solvent, surrounding the protein, have an impact on internal protein motions and, therefore, enzyme function. In this review, we describe recent biochemical and theoretical investigations of internal protein dynamics linked to enzyme catalysis. In the enzyme cyclophilin A, investigations have lead to the discovery of a network of protein vibrations promoting catalysis. Cyclophilin A catalyzes peptidyl-prolyl cis/trans isomerization in a variety of peptide and protein substrates. Recent studies of cyclophilin A are discussed in detail and other enzymes (dihydrofolate reductase and liver alcohol dehydrogenase) where similar discoveries have been reported are also briefly discussed. The detailed characterization of the discovered networks indicates that protein dynamics plays a role in rate-enhancement achieved by enzymes. An integrated view of enzyme structure, dynamics and function have wide implications in understanding allostericity, co-operative effects, as well as protein engineering of more efficient enzymes and novel drug design. [Abstract/Link to Full Text]

Retallack DM, Thomas TC, Shao Y, Haney KL, Resnick SM, Lee VD, Squires CH
Identification of anthranilate and benzoate metabolic operons of Pseudomonas fluorescens and functional characterization of their promoter regions.
Microb Cell Fact. 2006;51.
BACKGROUND: In an effort to identify alternate recombinant gene expression systems in Pseudomonas fluorescens, we identified genes encoding two native metabolic pathways that were inducible with inexpensive compounds: the anthranilate operon (antABC) and the benzoate operon (benABCD). RESULTS: The antABC and benABCD operons were identified by homology to the Acinetobacter sp. anthranilate operon and Pseudomonas putida benzoate operon, and were confirmed to be regulated by anthranilate or benzoate, respectively. Fusions of the putative promoter regions to the E. coli lacZ gene were constructed to confirm inducible gene expression. Each operon was found to be controlled by an AraC family transcriptional activator, located immediately upstream of the first structural gene in each respective operon (antR or benR). CONCLUSION: We have found the anthranilate and benzoate promoters to be useful for tightly controlling recombinant gene expression at both small (< 1 L) and large (20 L) fermentation scales. [Abstract/Link to Full Text]

Dutta D, De D, Chaudhuri S, Bhattacharya SK
Hydrogen production by Cyanobacteria.
Microb Cell Fact. 2005;436.
The limited fossil fuel prompts the prospecting of various unconventional energy sources to take over the traditional fossil fuel energy source. In this respect the use of hydrogen gas is an attractive alternate source. Attributed by its numerous advantages including those of environmentally clean, efficiency and renew ability, hydrogen gas is considered to be one of the most desired alternate. Cyanobacteria are highly promising microorganism for hydrogen production. In comparison to the traditional ways of hydrogen production (chemical, photoelectrical), Cyanobacterial hydrogen production is commercially viable. This review highlights the basic biology of cynobacterial hydrogen production, strains involved, large-scale hydrogen production and its future prospects. While integrating the existing knowledge and technology, much future improvement and progress is to be done before hydrogen is accepted as a commercial primary energy source. [Abstract/Link to Full Text]

Papi RM, Chaitidou SA, Trikka FA, Kyriakidis DA
Encapsulated Escherichia coli in alginate beads capable of secreting a heterologous pectin lyase.
Microb Cell Fact. 2005;435.
BACKGROUND: Production of heterologous proteins in the E. coli periplasm, or into the extracellular fluid has many advantages; therefore naturally occurring signal peptides are selected for proteins translocation. The aim of this study was the production in high yields of a recombinant pectin lyase that is efficiently secreted and the encapsulation of transformed E. coli cells for pectin degradation in a biotechnological process. RESULTS: The nucleotide sequence of Bacillus subtilis alpha-amylase's signal peptide was fused to the N-terminal of an heterologously expressed pectin lyase in E. coli BL21 [DE3]. Thus pectin lyase secretion was achieved into the extracellular growth medium. E. coli cells harboring the recombinant plasmid heterologously express pectin lyase to around 22% of the total cellular proteins, as it was estimated by SDS-PAGE and image analysis. IPTG induces the heterologously expressed enzyme, which is initially distributed extracellularly (7 hour) and later on at the periplasmic (9 hours) or cytosolic fraction (20 hours). No pectin lyase activity was found in the membranes fraction and in the inclusion bodies. Encapsulation of the recombinant strains of E. coli in alginate or alginate/silica beads 1:5 showed that pectin lyase could degrade effectively its substrate, for at least ten operational cycles. CONCLUSION: Secretion of an heterologously overexpressed pectin lyase in E. coli BL21 [DE3] was achieved in this study. For this purpose the signal peptide of alpha-amylase from B. subtilis was fused to the N-terminal domain of pectin lyase. Encapsulated E. coli BL21 [DE3] cells harboring pET29c/exPNL were used successfully for pectin degradation up to ten operational cycles indicating that under special conditions this might have biotechnological implementations. [Abstract/Link to Full Text]

Dümmler A, Lawrence AM, de Marco A
Simplified screening for the detection of soluble fusion constructs expressed in E. coli using a modular set of vectors.
Microb Cell Fact. 2005;434.
BACKGROUND: The solubility of recombinant proteins expressed in bacteria is often disappointingly low. Several strategies have been developed to improve the yield and one of the most common strategies is the fusion of the target protein with a suitable partner. Despite several reports on the successful use of each of these carriers to increase the solubility of some recombinant proteins, none of them was always successful and a combinatorial approach seems more efficient to identify the optimal combination for a specific protein. Therefore, the efficiency of an expression system critically depends on the speed in the identification of the optimal combination for the suitable fusion candidate in a screening process. This paper describes a set of expression vectors (pETM) designed for rapid subcloning, expression and subsequent purification using immobilized metal affinity chromatography (IMAC). RESULTS: A single PCR product of two Yellow Fluorescent Proteins (EYFPs) was cloned into 18 vectors comprising identical restriction sites and varying fusion partners as well as differing protease recognition sites. After a small-scale expression, the yields of the different constructs were compared using a Coomassie stained SDS-polyacrylamide gel and the results of this preliminary screening were then confirmed by large-scale purification. The yields were calculated and the stability of the different constructs determined using three independent conditions. The results indicated a significant correlation between the length and composition of non-native amino acid tails and stability. Furthermore, the buffer specificity of TEV and 3C proteases was tested using fusion proteins differing only in their protease recognition sequence, and a His-GST-EYFP construct was employed to compare the efficiency of the two alternative affinity purification methods. CONCLUSION: The experiments showed that the set of pETM vectors could be used for the rapid production of a large array of different constructs with specific yield, stability, and cleavage features. Their comparison allowed the identification of the optimal constructs to use for the large-scale expression. We expect that the approach outlined in this paper, i.e. the possibility to obtain in parallel fusion products of the target protein with different partners for a preliminary evaluation, would be highly beneficial for all them who are interested in the rapid identification of the optimal conditions for protein expression. [Abstract/Link to Full Text]

Gurkan C, Ellar DJ
Recombinant production of bacterial toxins and their derivatives in the methylotrophic yeast Pichia pastoris.
Microb Cell Fact. 2005;433.
The methylotrophic yeast Pichia pastoris is a popular heterologous expression host for the recombinant production of a variety of prokaryotic and eukaryotic proteins. The rapid emergence of P. pastoris as a robust heterologous expression host was facilitated by the ease with which it can be manipulated and propagated, which is comparable to that of Escherichia coli and Saccharomyces cerevisiae. P. pastoris offers further advantages such as the tightly-regulated alcohol oxidase promoter that is particularly suitable for heterologous expression of foreign genes. While recombinant production of bacterial toxins and their derivatives is highly desirable, attempts at their heterologous expression using the traditional E. coli expression system can be problematic due to the formation of inclusion bodies that often severely limit the final yields of biologically active products. However, recent literature now suggests that P. pastoris may be an attractive alternative host for the heterologous production of bacterial toxins, such as those from the genera Bacillus, Clostridium, and Corynebacterium, as well as their more complex derivatives. Here, we review the recombinant production of bacterial toxins and their derivatives in P. pastoris with special emphasis on their potential clinical applications. Considering that de novo design and construction of synthetic toxin genes have often been necessary to achieve optimal heterologous expression in P. pastoris, we also present general guidelines to this end based on our experience with the P. pastoris expression of the Bacillus thuringiensis Cyt2Aa1 toxin. [Abstract/Link to Full Text]

Banki MR, Wood DW
Inteins and affinity resin substitutes for protein purification and scale up.
Microb Cell Fact. 2005 Nov 11;432.
The development of self-cleaving fusion-tag technology has greatly simplified the purification of recombinant proteins at laboratory scale. The self-cleaving capability of these tags has recently been combined with additional purification tags to generate novel and convenient protein purification methods at a variety of scales. In this review, we describe some of these methods, and provide a rudimentary economic analysis of hypothetical large-scale applications. This work is expected to provide a rough outline for the evaluation of these methods for large-scale bioprocessing of a variety of products. [Abstract/Link to Full Text]

Hahn-Hägerdal B, Karhumaa K, Larsson CU, Gorwa-Grauslund M, Görgens J, van Zyl WH
Role of cultivation media in the development of yeast strains for large scale industrial use.
Microb Cell Fact. 2005 Nov 10;431.
The composition of cultivation media in relation to strain development for industrial application is reviewed. Heterologous protein production and pentose utilization by Saccharomyces cerevisiae are used to illustrate the influence of media composition at different stages of strain construction and strain development. The effects of complex, defined and industrial media are compared. Auxotrophic strains and strain stability are discussed. Media for heterologous protein production and for bulk bio-commodity production are summarized. [Abstract/Link to Full Text]

Frick O, Wittmann C
Characterization of the metabolic shift between oxidative and fermentative growth in Saccharomyces cerevisiae by comparative 13C flux analysis.
Microb Cell Fact. 2005 Nov 3;430.
BACKGROUND: One of the most fascinating properties of the biotechnologically important organism Saccharomyces cerevisiae is its ability to perform simultaneous respiration and fermentation at high growth rate even under fully aerobic conditions. In the present work, this Crabtree effect called phenomenon was investigated in detail by comparative 13C metabolic flux analysis of S. cerevisiae growing under purely oxidative, respiro-fermentative and predominantly fermentative conditions. RESULTS: The metabolic shift from oxidative to fermentative growth was accompanied by complex changes of carbon flux throughout the whole central metabolism. This involved a flux redirection from the pentose phosphate pathway (PPP) towards glycolysis, an increased flux through pyruvate carboxylase, the fermentative pathways and malic enzyme, a flux decrease through the TCA cycle, and a partial relocation of alanine biosynthesis from the mitochondrion to the cytosol. S. cerevisiae exhibited a by-pass of pyruvate dehydrogenase in all physiological regimes. During oxidative growth this by-pass was mainly provided via pyruvate decarboxylase, acetaldehyde dehydrogenase, acetyl-CoA synthase and transport of acetyl-CoA into the mitochondrion. During fermentative growth this route, however, was saturated due to limited enzyme capacity. Under these conditions the cells exhibited high carbon flux through a chain of reactions involving pyruvate carboxylase, the oxaloacetate transporter and malic enzyme. During purely oxidative growth the PPP alone was sufficient to completely supply NADPH for anabolism. During fermentation, it provided only 60 % of the required NADPH. CONCLUSION: We conclude that, in order to overcome the limited capacity of pyruvate dehydrogenase, S. cerevisiae possesses different metabolic by-passes to channel carbon into the mitochondrion. This involves the conversion of cytosolic pyruvate either into acetyl CoA or oxaloacetate followed by intercompartmental transport of these metabolites. During oxidative growth mainly the NAD specific isoforms of acetaldehyde dehydrogenase and isocitrate dehydrogenase catalyze the corresponding reactions in S. cerevisiae, whereas NADPH supply under fermentative conditions involves significant contribution of sources other than the PPP such as e. g. NADPH specific acetaldehyde dehydrogenase or isocitrate dehydrogenase. [Abstract/Link to Full Text]

Hibbert EG, Dalby PA
Directed evolution strategies for improved enzymatic performance.
Microb Cell Fact. 2005 Oct 7;429.
The engineering of enzymes with altered activity, specificity and stability, using directed evolution techniques that mimic evolution on a laboratory timescale, is now well established. However, the general acceptance of these methods as a route to new biocatalysts for organic synthesis requires further improvement of the methods for both ease-of-use and also for obtaining more significant changes in enzyme properties than is currently possible. Recent advances in library design, and methods of random mutagenesis, combined with new screening and selection tools, continue to push forward the potential of directed evolution. For example, protein engineers are now beginning to apply the vast body of knowledge and understanding of protein structure and function, to the design of focussed directed evolution libraries, with striking results compared to the previously favoured random mutagenesis and recombination of entire genes. Significant progress in computational design techniques which mimic the experimental process of library screening is also now enabling searches of much greater regions of sequence-space for those catalytic reactions that are broadly understood and, therefore, possible to model. Biocatalysis for organic synthesis frequently makes use of whole-cells, in addition to isolated enzymes, either for a single reaction or for transformations via entire metabolic pathways. As many new whole-cell biocatalysts are being developed by metabolic engineering, the potential of directed evolution to improve these initial designs is also beginning to be realised. [Abstract/Link to Full Text]

Blecha A, Zarschler K, Sjollema KA, Veenhuis M, Rödel G
Expression and cytosolic assembly of the S-layer fusion protein mSbsC-EGFP in eukaryotic cells.
Microb Cell Fact. 2005 Oct 4;428.
BACKGROUND: Native as well as recombinant bacterial cell surface layer (S-layer) protein of Geobacillus (G.) stearothermophilus ATCC 12980 assembles to supramolecular structures with an oblique symmetry. Upon expression in E. coli, S-layer self assembly products are formed in the cytosol. We tested the expression and assembly of a fusion protein, consisting of the mature part (aa 31-1099) of the S-layer protein and EGFP (enhanced green fluorescent protein), in eukaryotic host cells, the yeast Saccharomyces cerevisiae and human HeLa cells. RESULTS: Upon expression in E. coli the recombinant mSbsC-EGFP fusion protein was recovered from the insoluble fraction. After denaturation by Guanidine (Gua)-HCl treatment and subsequent dialysis the fusion protein assembled in solution and yielded green fluorescent cylindric structures with regular symmetry comparable to that of the authentic SbsC. For expression in the eukaryotic host Saccharomyces (S.) cerevisiae mSbsC-EGFP was cloned in a multi-copy expression vector bearing the strong constitutive GPD1 (glyceraldehyde-3-phosophate-dehydrogenase) promoter. The respective yeast transfomants were only slightly impaired in growth and exhibited a needle-like green fluorescent pattern. Transmission electron microscopy (TEM) studies revealed the presence of closely packed cylindrical structures in the cytosol with regular symmetry comparable to those obtained after in vitro recrystallization. Similar structures are observed in HeLa cells expressing mSbsC-EGFP from the Cytomegalovirus (CMV IE) promoter. CONCLUSION: The mSbsC-EGFP fusion protein is stably expressed both in the yeast, Saccharomyces cerevisiae, and in HeLa cells. Recombinant mSbsC-EGFP combines properties of both fusion partners: it assembles both in vitro and in vivo to cylindrical structures that show an intensive green fluorescence. Fusion of proteins to S-layer proteins may be a useful tool for high level expression in yeast and HeLa cells of otherwise instable proteins in their native conformation. In addition the self assembly properties of the fusion proteins allow their simple purification. Moreover the binding properties of the S-layer part can be used to immobilize the fusion proteins to various surfaces. Arrays of highly ordered and densely structured proteins either immobilized on surfaces or within living cells may be advantageous over the respective soluble variants with respect to stability and their potential interference with cellular metabolism. [Abstract/Link to Full Text]

García-Fruitós E, González-Montalbán N, Morell M, Vera A, Ferraz RM, Arís A, Ventura S, Villaverde A
Aggregation as bacterial inclusion bodies does not imply inactivation of enzymes and fluorescent proteins.
Microb Cell Fact. 2005 Sep 12;427.
BACKGROUND: Many enzymes of industrial interest are not in the market since they are bio-produced as bacterial inclusion bodies, believed to be biologically inert aggregates of insoluble protein. RESULTS: By using two structurally and functionally different model enzymes and two fluorescent proteins we show that physiological aggregation in bacteria might only result in a moderate loss of biological activity and that inclusion bodies can be used in reaction mixtures for efficient catalysis. CONCLUSION: This observation offers promising possibilities for the exploration of inclusion bodies as catalysts for industrial purposes, without any previous protein-refolding step. [Abstract/Link to Full Text]


Recent Articles in Antimicrobial Agents and Chemotherapy

Pradines B, Torrentino-Madamet M, Fontaine A, Henry M, Baret E, Mosnier J, Briolant S, Fusai T, Rogier C
Atorvastatin is 10-fold more active in vitro than other statins against Plasmodium falciparum.
Antimicrob Agents Chemother. 2007 Jul;51(7):2654-5. [Abstract/Link to Full Text]

Cattoir V, Poirel L, Nordmann P
Plasmid-mediated quinolone resistance determinant QnrB4 identified in France in an Enterobacter cloacae clinical isolate coexpressing a QnrS1 determinant.
Antimicrob Agents Chemother. 2007 Jul;51(7):2652-3. [Abstract/Link to Full Text]

Suvorov M, Vakulenko SB, Mobashery S
Cytoplasmic-membrane anchoring of a class A beta-lactamase and its capacity in manifesting antibiotic resistance.
Antimicrob Agents Chemother. 2007 Aug;51(8):2937-42.
Bacterial beta-lactamases are the major causes of resistance to beta-lactam antibiotics. Three classes of these enzymes are believed to have evolved from ancestral penicillin-binding proteins (PBPs), enzymes responsible for bacterial cell wall biosynthesis. Both beta-lactamases and PBPs are able to efficiently form acyl-enzyme species with beta-lactam antibiotics. In contrast to beta-lactamases, PBPs are unable to efficiently turn over antibiotics and therefore are susceptible to inhibition by beta-lactam compounds. Although both PBPs and gram-negative beta-lactamases operate in the periplasm, PBPs are anchored to the cytoplasmic membrane, but beta-lactamases are not. It is believed that beta-lactamases shed the membrane anchor in the course of evolution. The significance of this event remains unclear. In an attempt to demonstrate any potential influence of the membrane anchor on the overall biological consequences of beta-lactamases, we fused the TEM-1 beta-lactamase to the C-terminal membrane-anchor of penicillin-binding protein 5 (PBP5) of Escherichia coli. The enzyme was shown to express well in E. coli and was anchored to the cytoplasmic membrane. Expression of the anchored enzyme did not result in any changes in antibiotic resistance pattern of bacteria or growth rates. However, in the process of longer coincubation, the organism that harbored the plasmid for the anchored TEM-1 beta-lactamase lost out to the organism transformed by the plasmid for the nonanchored enzyme over a period of 8 days of continuous growth. The effect would appear to be selection of a variant that eliminates the problematic protein through elimination of the plasmid that encodes it and not structural or catalytic effects at the protein level. It is conceivable that an evolutionary outcome could be the shedding of the sequence for the membrane anchor or alternatively evolution of these enzymes from nonanchored progenitors. [Abstract/Link to Full Text]

Cenizal MJ, Skiest D, Luber S, Bedimo R, Davis P, Fox P, Delaney K, Hardy RD
Prospective randomized trial of empiric therapy with trimethoprim-sulfamethoxazole or doxycycline for outpatient skin and soft tissue infections in an area of high prevalence of methicillin-resistant Staphylococcus aureus.
Antimicrob Agents Chemother. 2007 Jul;51(7):2628-30.
To evaluate empirical therapy with trimethoprim-sulfamethoxazole or doxycycline for outpatient skin and soft tissue infections in an area of high prevalence of methicillin-resistant Staphylococcus aureus, a randomized, prospective, open-label investigation was performed. The overall clinical failure rate was 9%, with all failures occurring in the trimethoprim-sulfamethoxazole group. However, there was no significant difference between the clinical failure rate of empirical trimethoprim-sulfamethoxazole therapy and that of doxycycline therapy. [Abstract/Link to Full Text]

Reeves DM, Nagarajan U, O'Connell C, Andrews CW, Darville T
Lack of an effect of antibiotic treatment on prolonged detection of chlamydial DNA in murine genital tract infection.
Antimicrob Agents Chemother. 2007 Jul;51(7):2646-8.
Mice treated with antibiotics early or late after active infection had resolved were examined for chlamydial DNA in endocervical swabs. The early eradication of infection limited oviduct pathology, despite the continued detection of chlamydial DNA by nested PCR. Late antibiotic treatment had no effect on the ability to detect DNA or oviduct pathology. [Abstract/Link to Full Text]

Cheng J, Thanassi JA, Thoma CL, Bradbury BJ, Deshpande M, Pucci MJ
Dual targeting of DNA gyrase and topoisomerase IV: target interactions of heteroaryl isothiazolones in Staphylococcus aureus.
Antimicrob Agents Chemother. 2007 Jul;51(7):2445-53.
Heteroaryl isothiazolones (HITZs) are antibacterial agents that display excellent in vitro activity against Staphylococcus aureus. We recently identified a series of these compounds that show potent bactericidal activities against methicillin-resistant Staphylococcus aureus (MRSA). We report here the results of in vitro resistance studies that reveal potential underlying mechanisms of action. HITZs selected gyrA mutations exclusively in first-step mutants of wild-type S. aureus, indicating that in contrast to the case with most quinolones, DNA gyrase is the primary target. The compounds displayed low mutation frequencies (10(-9) to 10(-10)) at concentrations close to the MICs and maintained low MICs (< or =0.016 microg/ml) against mutants with single mutations in either gyrA or grlA (parC). These data suggested that HITZs possess significant inhibitory activities against target enzymes, DNA gyrase and topoisomerase IV. This dual-target inhibition was supported by low 50% inhibitory concentrations against topoisomerase IV as measured in a decatenation activity assay and against DNA gyrase as measured in a supercoiling activity assay. Good antibacterial activities (< or =1 microg/ml) against staphylococcal gyrA grlA double mutants, as well as low frequencies (10(-9) to 10(-10)) of selection of still higher-level mutants, also suggested that HITZs remained active against mutant enzymes. We further demonstrated that HITZs exhibit good inhibition of both S. aureus mutant enzymes and thus continue to possess a novel dual-targeting mode of action against these mutant strains. In stepwise acquisition of mutations, HITZs selected quinolone resistance determining region mutations gyrA(Ser84Leu), grlA(Ser80Phe), grlA(Ala116Val), and gyrA(Glu88Lys) sequentially, suggesting that the corresponding amino acids are key amino acids involved in the binding of HITZs to topoisomerases. The overall profile of these compounds suggests the potential utility of HITZs in combating infections caused by S. aureus, including multidrug-resistant MRSA. [Abstract/Link to Full Text]

Colquhoun DJ, Aarflot L, Melvold CF
gyrA and parC Mutations and associated quinolone resistance in Vibrio anguillarum serotype O2b strains isolated from farmed Atlantic cod (Gadus morhua) in Norway.
Antimicrob Agents Chemother. 2007 Jul;51(7):2597-9.
MIC testing of Vibrio anguillarum isolates recovered from diseased farmed Atlantic cod revealed oxolinic acid MICs of < or =0.001, 0.06, and 16 microg ml(-1). Single gyrA Ser-Ile substitutions were identified at position 83 of the intermediate and resistant strains, while a parC Ser-Leu substitution at position 85 was found only in the resistant strain. [Abstract/Link to Full Text]

Shin JH, Jung HJ, Kim HR, Jeong J, Jeong SH, Kim S, Lee EY, Lee JN, Chang CL
Prevalence, characteristics, and molecular epidemiology of macrolide and fluoroquinolone resistance in clinical isolates of Streptococcus pneumoniae at five tertiary-care hospitals in Korea.
Antimicrob Agents Chemother. 2007 Jul;51(7):2625-7.
The genes erm(B), mef(A), and both erm(B) and mef(A) were identified in 42.6, 10.1, and 47.3%, respectively, of the erythromycin-resistant Streptococcus pneumoniae isolates. Of the strains, 3.8% were nonsusceptible to levofloxacin and had 1 to 6 amino acid changes in the quinolone resistance-determining region, including a new mutation, Asn94Ser, in the product of parC. Levofloxacin with reserpine was highly specific for efflux screening. [Abstract/Link to Full Text]

Meehl M, Herbert S, Götz F, Cheung A
Interaction of the GraRS two-component system with the VraFG ABC transporter to support vancomycin-intermediate resistance in Staphylococcus aureus.
Antimicrob Agents Chemother. 2007 Aug;51(8):2679-89.
Current treatment for serious infections caused by methicillin-resistant Staphylococcus aureus relies heavily upon the glycopeptide antibiotic vancomycin. Unfortunately, this practice has led to an intermediate resistance phenotype that is particularly difficult to treat in invasive staphylococcal diseases, such as septicemia and its metastatic complications, including endocarditis. Although the vancomycin-intermediate resistance phenotype has been linked to abnormal cell wall structures and autolytic rates, the corresponding genetic changes have not been fully elucidated. Previously, whole-genome array studies listed numerous genes that are overexpressed in vancomycin-intermediate sensitive strains, including graRS (SACOL0716 to -0717), encoding a two-component regulatory system (TCRS), as well as the adjacent vraFG (SACOL0718 to -0720), encoding an ATP-binding cassette (ABC) transporter; but the exact contribution of these genes to increased vancomycin resistance has not been define