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  • Change Your Conference Experience by Submitting an ASM Microbe 2019 Session Proposal
    07/19/2018
  • ASM-Mentored Tuberculosis Laboratory in Zambia Recommended for First International Accreditation
    07/19/2018
  • Who Is Spreading Viruses without Knowing it?
    07/16/2018
  • Opening the Black Box of MALDI-TOF MS
    07/16/2018
  • Can Plants with Microbial Enzymes Help Clean up Excess Chemicals?
    07/13/2018
  • Presentation Tips: A Page From Teaching
    07/11/2018
  • The Clinical Microbiology Open: An Attendee's Perspective
    07/09/2018
  • Microbial Minutes: New Phage Research Center, Syphilis Research Breakthrough, and Polio Updates
    07/02/2018
  • Leading and following: busting a move for breakpoint interpretations
    07/02/2018
  • Drug Resistance Gene Expression Differs between Males and Females in Gonorrhea Infections
    06/29/2018

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  • Friday, 20 July 2018

    Motility is generally conserved among many animal and plant pathogens. Environmental conditions, however, significantly impact expression of the motile phenotype. In this study, we describe a novel heterogeneous motility phenotype in Pseudomonas syringae, where under normally suppressive incubation conditions (30C) punctate colonies arise that are spatially isolated from the point of inoculation, giving rise to a motility pattern we term constellation swimming (CS). We demonstrate that this phenotype is reproducible, reversible, and dependent on a functioning flagellum. Mirroring the heterogeneous motility phenotype, we demonstrate the existence of a sub-population of cells under non-permissive conditions that express flagellin (fliC) at levels...

  • Friday, 20 July 2018

    Leprosy is a chronic infection where the skin and peripheral nervous system is invaded by Mycobacterium leprae. The infection mechanism remains unknown in part because culture methods have not been established yet for M.leprae. Mce1A protein (442 aa) is coded by mce1A (1326 bp) of M.leprae. The mce1A homolog in Mycobacterium tuberculosis is known to be associated with M.tuberculosis epithelial cell entry, and survival and multiplication within macrophages. Studies using recombinant proteins have indicated that mce1A of M.leprae is also associated with epithelial cell entry. This study is aimed at identifying particular sequences within mce1A associated with M.leprae epithelial cell...

  • Friday, 20 July 2018

    Trophic interactions in the microbial food web of soils are crucial for nutrient and carbon cycling. Traditionally, protozoa are considered the major micropredators of bacteria in soil. However, some prokaryotes, such as Myxobacteria and Bdellovibrio are also famous for bacterivorous life style. Until recently, it was impossible to assess the abundance of pro- and eukaryotic micropredators in soils simultaneously. Using a metatranscriptomic three-domain profiling of small subunit ribosomal RNA we investigated the abundance of bacterivores in 28 datasets from eleven European mineral and organic soils of different climatic zones. In all soils, Myxobacteria comprised a significant proportion from 6 to...

  • Friday, 20 July 2018

    Viral genomes exhibit a higher gene density and more diversified transcriptome than the host cell. Coding potential is maximized through the use of multiple reading frames, placement of genes on opposing strands, inefficient or modified use of termination signals, and the deployment of complex alternative splicing patterns. As a consequence, detailed characterization of viral transcriptomes by conventional methods can be challenging. Full length native RNA sequencing (nRNA-seq) using nanopore arrays offers an exciting alternative. Individual transcripts are sequenced directly, without the biases inherent to the recoding or amplification steps included in other sequencing methodologies. nRNA-seq simplifies the detection of variation...

  • Friday, 20 July 2018

    Interferon (IFN) inhibits HIV replication by inducing an array of antiviral effectors. Here we describe a novel CRISPR knockout screening approach to identify the ensemble of these HIV restriction factors. We assembled a CRISPR sgRNA library specific for Interferon Stimulated Genes (ISGs) into a modified lentiviral vector that allows for packaging of sgRNA-encoding genomes in trans into budding HIV-1 particles. We observed that knockout of Zinc Antiviral Protein (ZAP) improved the performance of the screen due to ZAP-mediated inhibition of the vector. We identify a small panel of IFN-induced HIV restriction factors, including MxB, IFITM1, Tetherin/BST2 and TRIM5 which together...

  • Thursday, 19 July 2018

    During their life cycles, pathogens have to adapt to many biotic and abiotic environmental constraints to maximize their overall fitness. Morphological transitions are one of the least understood of the many strategies employed by fungal plant pathogens to adapt to constantly changing environments. We characterized the responses of the wheat pathogen Zymoseptoria tritici to a series of environmental stimuli using microscopy, transcriptomic analyses, and survival assays to explore the effects of changing environments on morphology and adaptation. We found that all tested stimuli induced morphological changes, with distinct responses observed among four different strains. The transcription analyses indicated a co-regulation...

  • Thursday, 19 July 2018

    Introduction: Ciprofloxacin resistance in Escherichia coli is widespread and adds to the burden of E. coli infections. Reviews assessing the genetic basis of ciprofloxacin resistance have mostly been qualitative. However, to allow for the prediction of a resistance phenotype of clinical relevance based on genotypic characteristics, it is essential to quantify the contribution of prevalent genotypic determinants to resistance. We carried out a systematic review to assess the relative contribution of currently known genomic resistance determinants to the minimum inhibitory concentration (MIC) of ciprofloxacin in E. coli. Methods: PubMed and Web of Science were searched for English language studies that...

  • Thursday, 19 July 2018

    Human norovirus (HuNoV) is the leading cause of acute gastroenteritis and is spread by fecal shedding that can often persist for weeks to months after infection. Murine norovirus (MNV) is also shed persistently in the feces and provides a tractable model to study molecular mechanisms of enteric persistence. Previous studies have identified non-structural protein 1 (NS1) from the persistent MNV strain CR6 as critical for persistent infection in intestinal epithelial cells (IECs), but its mechanism of action remains unclear. We now find that the function of NS1 in promoting persistence is regulated by apoptosis. Following induction of apoptosis in infected...

  • Wednesday, 18 July 2018

    We discovered a virus infecting Entomophthora muscae, a behavior-manipulating fungal pathogen of dipterans. The virus, which we name Entomophthovirus, is a capsid-forming, positive-strand RNA virus in the viral family iflaviridae, whose known members almost exclusively infect insects. We show that the virus RNA is expressed at high levels in fungal cells in vitro and during in vivo infections of Drosophila melanogaster, and that virus particles are present in E. muscae. Two close relatives of the virus had been previously described as insect viruses based on the presence of viral genomes in transcriptomes assembled from RNA extracted from wild dipterans. By...

  • Wednesday, 18 July 2018

    Plasmodium parasites possess a protein with homology to Niemann-Pick Type C1 proteins (Plasmodium falciparum Niemann-Pick Type C1-Related protein, PfNCR1). We isolated parasites with resistance-conferring mutations in PfNCR1 during selections with three diverse small-molecule antimalarial compounds and show that the mutations are causative for compound resistance. PfNCR1 protein knockdown results in severely attenuated growth and confers hypersensitivity to the compounds. Compound treatment or protein knockdown leads to increased sensitivity of the parasite plasma membrane (PPM) to the amphipathic glycoside saponin and engenders digestive vacuoles (DVs) that are small and malformed. Immuno-electron microscopy and split-GFP experiments localize PfNCR1 to the PPM. Our...

  • Wednesday, 18 July 2018

    Acylated amino acids function as important components of the cellular membrane in some bacteria. Biosynthesis is initiated by the N-acylation of the amino acid and this is followed by subsequent O-acylation of the acylated molecule resulting in the production of the mature diacylated amino acid lipid. In this study we use both genetics and liquid chromatography-mass spectrometry (LC-MS) to characterize the biosynthesis and function of novel diacylated glycine lipid (GL) species in Bacteroides thetaiotaomicron. We, and others, have previously reported the identification of a gene, named glsB in this study, that encodes a N-acyltransferase activity responsible for the production of...

  • Wednesday, 18 July 2018

    The gut microbiome is now widely recognized as a dynamic ecosystem that plays an important role in health and disease. While current sequencing technologies make it possible to estimate relative abundances of host-associated bacteria over time, the biological processes governing their dynamics remain poorly understood. Therefore, as in other ecological systems, it is important to identify quantitative relationships describing global aspects of gut microbiota dynamics. Here we use multiple high-resolution time series data obtained from humans and mice to demonstrate that despite their inherent complexity, gut microbiota dynamics can be characterized by several robust scaling relationships. Remarkably, these patterns are...

  • Wednesday, 18 July 2018

    Bacteria switch only intermittently to motile planktonic lifestyles under favourable conditions. Under chronic nutrient deprivation, however, bacteria orchestrate a switch to stationary phase, conserving energy by altering metabolism and stopping motility. About two-thirds of bacteria use flagella to swim, but how bacteria deactivate this large-molecular machine remains poorly studied. Here we describe the previously unreported ejection of polar sodium-driven motors by {gamma}-proteobacteria. We show that these bacteria eject their flagella at the base of the flagellar hook when nutrients are depleted, leaving a relic of a former flagellar motor in the outer-membrane. Subtomogram averages of the full motor and relic...

  • Tuesday, 17 July 2018

    All viruses require strategies to inhibit or evade the immunity pathways of cells they infect. The viruses that infect bacteria, bacteriophages (phages), must avoid nucleic-acid targeting immune pathways such as CRISPR-Cas and restriction endonucleases to replicate efficiently1. Here, we show that a jumbo phage infecting Pseudomonas aeruginosa, phage {varphi}KZ, is resistant to many immune systems in vivo, including CRISPR-Cas3 (Type I-C), Cas9 (Type II-A), Cas12 (Cpf1, Type V-A), and Type I restriction-modification (R-M) systems. We propose that {varphi}KZ utilizes a nucleus-like shell to protect its DNA from attack. Supporting this, we demonstrate that Cas9 is able to cleave {varphi}KZ DNA...

  • Tuesday, 17 July 2018

    Dengue virus (DENV) is a mosquito-borne virus of the family Flaviviridae. The RNA viral genome encodes for a polyprotein that is co-translationally processed into three structural proteins and seven non-structural proteins. The non-structural protein 1 (NS1) is a multifunctional viral protein actively secreted in vertebrate and mosquito cells during DENV infection. In mosquito cells, NS1 is secreted in a caveolin-1 (CAV-1) dependent manner by an unconventional pathway. The caveolin chaperone complex (CCC) is a cytoplasmic complex formed by caveolin-1 and the chaperones FKBP52, Cy40 and CyA which is responsible for cholesterol traffic inside the cell. In this work, we demonstrate...

  • Tuesday, 17 July 2018

    Many Gram-negative bacteria use type VI secretion systems (T6SS) to translocate effector proteins into eukaryotic or prokaryotic cells. Francisella possesses a non-canonical T6SS encoded on the Francisella pathogenicity island (FPI) that is essential for efficient phagosomal escape and access to the cytosol of infected host cells. Using a global and site-specific phosphoproteomic analysis of Francisella, we identified a unique phosphorylation site on tyrosine 139 of IglB, the TssC homologue and a key component of the T6SS contractile sheath. Phosphorylated IglB was exclusively found in the non-oligomerized form of the protein, suggesting that sheath assembly requires IglB dephosphorylation. All the different...

  • Tuesday, 17 July 2018

    As human population density and antibiotic exposure increases, specialised bacterial subtypes have begun to emerge. Arising among species that are common commensals and infrequent pathogens, antibiotic-resistant 'high-risk clones' have evolved to better survive in the modern human. Here, we show that the major matrix porin (OmpK35) of Klebsiella pneumoniae is not required in the mammalian host for colonisation, pathogenesis, nor for antibiotic resistance, and that it is commonly absent in pathogenic isolates. This is found in association with, but apparently independent of, a highly specific change in the co-regulated partner porin, the osmoporin (OmpK36), which provides enhanced antibiotic resistance without...

  • Monday, 16 July 2018

    The successful elimination of bacteria such as Streptococcus pneumoniae from a host involves the coordination between different parts of the immune system. Previous studies have explored the effects of the initial pneumococcal load (bacterial dose) on different representations of innate immunity, finding that pathogenic outcomes can vary with the size of the bacterial dose. However, others yield support to the notion of dose-independent factors contributing to bacterial clearance. In this paper, we seek to provide a deeper understanding of the immune responses associated to the pneumococcus. To this end, we formulate a model that realizes an abstraction of the innate-regulatory...

  • Monday, 16 July 2018

    The yeast Candida albicans is an opportunistic pathogen of humans, meaning that despite commensal interactions with its host, it can transition to a harmful pathogen. While C. albicans is the predominant species isolated in the human mycobiome and implicated in fungal infection, infections due to non-albicans Candida species are rapidly rising. Studying the factors that contribute to virulence is often challenging and frequently depends on many contexts including host immune status and pathogen genetic background. Here, we utilize the nematode Caenorhabditis elegans as a perspicuous and efficient model host system to study fungal infections of Candida pathogens. We find that...

  • Monday, 16 July 2018

    Bacteraemia is a risk factor for subsequent clinical deterioration and death. Current reliance on culture-based methods for detection of bacteraemia delays identification and assessment of this risk until after the optimal period for positively impacting treatment decisions has passed. Therefore, a method for rapid detection and identification of bacterial infection in the peripheral bloodstream in acutely ill patients is crucial for improved patient survival through earlier targeted antibiotic treatment. The turnaround time for current clinical laboratory methods ranges from 12 to 48 hours, emphasizing the need for a faster diagnostic test. Here we describe a novel assay for accelerated detection...

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