The genome and proteome of a virulent Escherichia coli O157:H7 bacteriophage closely resembling Salmonella phage Felix O1

Based upon whole genome and proteome analysis, Escherichia coli O157:H7-specific bacteriophage (phage) wV8 belongs to the new myoviral genus, "the Felix O1-like viruses" along with Salmonella phage Felix O1 and Erwinia amylovora phage φEa21-4. The genome characteristics of phage wV8 (size 88.49 kb, mol%G+C 38.9, 138 ORFs, 23 tRNAs) are very similar to those of phage Felix O1 (86.16 kb, 39.0 mol%G+C, 131 ORFs and 22 tRNAs) and, indeed most of the proteins have their closest homologs within Felix O1. Approximately one-half of the Escherichia coli O157:H7 mutants resistant to phage wV8 still serotype as O157:H7 indicating that this phage may recognize, like coliphage T4, two different surface receptors: lipopolysaccharide and, perhaps, an outer membrane protein

Inroads through the bacterial cell envelope: seeing is believing

A singular feature of all prokaryotic cells in the presence of a cell envelope comprised of a cytoplasmic membrane and a cell wall. The introduction of bacterial cell fractionation techniques in the 1950's and 1960's along with developments in procedures for electron microscopy 'opened the window' towards an understanding of the chemical composition and architecture of the cell envelope. This review traces the contribution of Terry Beveridge in these endeavours, beginning with his doctoral studies in the 1970's on the structure of paracrystalline surface arrays (S-layers) followed by an exploration of cryogenic methods for preserving bacteria for ultrastructural analyses. His insights are reflected in a current example of the contribution of cryoelectron microscopy to S-layer studies - the structure and assembly of the surface array of Caulobacter crescentus. The review then focuses on Terry's contributions to imaging the ultrastructure of bacterial cell envelopes and to the development of cryoelectron microscopy techniques, including the use of CEMOVS (Cryoelectron Microscopy of Vitreous Sections) to 'see' the ultrastructure of the Gram-positive cell envelope - his last scientific endeavour.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Endemic bacteriophages: a cautionary tale for evaluation of bacteriophage therapy and other interventions for infection control in animals

<p>Abstract</p> <p>Background</p> <p>One of the most effective targets for control of zoonotic foodborne pathogens in the farm to fork continuum is their elimination in food animals destined for market. Phage therapy for <it>Escherichia coli</it> O157:H7 in ruminants, the main animal reservoir of this pathogen, is a popular research topic. Since phages active against this pathogen may be endemic in host animals and their environment, they may emerge during trials of phage therapy or other interventions, rendering interpretation of trials problematic.</p> <p>Methods</p> <p>During separate phage therapy trials, sheep and cattle inoculated with 10⁹ to 10¹⁰ CFU of <it>E. coli</it> O157:H7 soon began shedding phages dissimilar in plaque morphology to the administered therapeutic phages. None of the former was previously identified in the animals or in their environment. The dissimilar “rogue” phage was isolated and characterized by host range, ultrastructure, and genomic and proteomic analyses.</p> <p>Results</p> <p>The “rogue” phage (Phage vB_EcoS_Rogue1) is distinctly different from the administered therapeutic <it>Myoviridae</it> phages, being a member of the <it>Siphoviridae</it> (head: 53 nm; striated tail: 152 x 8 nm). It has a 45.8 kb genome which is most closely related to coliphage JK06, a member of the “T1-like viruses” isolated in Israel. Detailed bioinformatic analysis reveals that the tail of these phages is related to the tail genes of coliphage lambda. The presence of “rogue” phages resulting from natural enrichments can pose problems in the interpretation of phage therapeutic studies. Similarly, evaluation of any interventions for foodborne or other bacterial pathogens in animals may be compromised unless tests for such phages are included to identify their presence and potential impact.</p