Regulatory interplay between Escherichia coli O157:H7 factors governing cattle colonisation by manipulation of innate immunity

Abstract

Event Abstract Back to Event Regulatory interplay between Escherichia coli O157:H7 factors governing cattle colonisation by manipulation of innate immunity David Gally1* 1 University of, Division of Immunity and Infection, United Kingdom Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is the most common EHEC serotype associated with human disease in the United Kingdom, with about 1000 cases a year. The bacterium originates from ruminant hosts, in particular cattle, where it colonises the terminal rectum. EHEC O157 colonisation of cattle is not associated with disease and this is mainly due to the different distribution of Gb3/CD77 Shiga toxin (Stx) receptors in cattle compared with humans. While the basis to the rectal tropism is still unclear a number of factors contribute to attachment at this site and therefore persistence in cattle. H7 flagella are involved in initial interactions followed by intimate binding conferred by a type III secretion system (T3SS). Vaccines combining antigens from these two systems have been shown to reduce both the number of cattle colonized and the level of bacterial excretion from animals that do become colonized following oral challenge with EHEC O157. Phage typing has been commonly applied to examine EHEC subpopulations; over the last decade EHEC O157 PT21/28 has been associated with the majority of human infections in the UK, although this now appears to be changing. A comprehensive study of cattle in Scotland, over the same period, showed that the same PT was common in cattle and was also more likely than other phage types to be sampled from cattle excreting high levels of the bacteria. Our previous work has also shown that T3S levels and regulation vary considerably between EHEC O157 strains. A key aim for our research is to understand the key genetic differences between strains underlying their capacity to be associated with disease. The simplest hypothesis being that higher or longer term shedding increases the environmental load and the likelihood of human infection. Our research is focused on the contribution of prophages, both functional and cryptic, to EHEC colonization of cattle. Genes encoding Stx and effector proteins secreted by the T3S system have been integrated into the EHEC genome as prophages and both contribute to innate response manipulation presumably to promote persistence in the bovine host. Our recent work now demonstrates that several of these prophages also control expression of T3S. Taken together, it is proposed that the prophage repertoire of an EHEC O157 strain is a critical determinant of colonization capacity and excretion level (Fig. 1). This talk will focus on this control and mathematical modeling of colonization that has provided novel insights into the timing and role of the innate response in restricting EHEC O157 colonisation in cattle and therefore why this response the key target for Stx and bacterial effector proteins. Keywords: EHEC O157:H7, Phage typing, Prophages, STX, type III secretion system Conference: ECMIS - E. coli and the Mucosal Immune System : Interaction, Modulation and Vaccination, Ghent, Belgium, 2 Jul - 5 Jul, 2011. Presentation Type: Oral Presentation Topic: Infection and innate immunity, immunosupression and/or immunostimulation Citation: Gally D (2011). Regulatory interplay between Escherichia coli O157:H7 factors governing cattle colonisation by manipulation of innate immunity. Front. Immunol. Conference Abstract: ECMIS - E. coli and the Mucosal Immune System : Interaction, Modulation and Vaccination. doi: 10.3389/conf.fimmu.2011.01.00020 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 22 Sep 2011; Published Online: 13 Oct 2011. * Correspondence: Prof. David Gally, University of, Division of Immunity and Infection, Edinburgh, United Kingdom, d.gally@ed.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers David Gally Google David Gally Google Scholar David Gally PubMed David Gally Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.