51
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Kakkanat A, Totsika M, Schaale K, Duell BL, Lo AW, Phan MD, Moriel DG, Beatson SA, Sweet MJ, Ulett GC, Schembri MA. The role of H4 flagella in Escherichia coli ST131 virulence. Sci Rep 2015; 5:16149. [PMID: 26548325 PMCID: PMC4637896 DOI: 10.1038/srep16149] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 10/02/2015] [Indexed: 01/04/2023] Open
Abstract
Escherichia coli sequence type 131 (ST131) is a globally dominant multidrug resistant clone associated with urinary tract and bloodstream infections. Most ST131 strains exhibit resistance to multiple antibiotics and cause infections associated with limited treatment options. The largest sub-clonal ST131 lineage is resistant to fluoroquinolones, contains the type 1 fimbriae fimH30 allele and expresses an H4 flagella antigen. Flagella are motility organelles that contribute to UPEC colonisation of the upper urinary tract. In this study, we examined the specific role of H4 flagella in ST131 motility and interaction with host epithelial and immune cells. We show that the majority of H4-positive ST131 strains are motile and are enriched for flagella expression during static pellicle growth. We also tested the role of H4 flagella in ST131 through the construction of specific mutants, over-expression strains and isogenic mutants that expressed alternative H1 and H7 flagellar subtypes. Overall, our results revealed that H4, H1 and H7 flagella possess conserved phenotypes with regards to motility, epithelial cell adhesion, invasion and uptake by macrophages. In contrast, H4 flagella trigger enhanced induction of the anti-inflammatory cytokine IL-10 compared to H1 and H7 flagella, a property that may contribute to ST131 fitness in the urinary tract.
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Affiliation(s)
- Asha Kakkanat
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
| | - Makrina Totsika
- Institute of Health and Biomedical Innovation, School of Biomedical Sciences, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Kolja Schaale
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Benjamin L Duell
- School of Medical Science, and Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Alvin W Lo
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
| | - Danilo G Moriel
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
| | - Scott A Beatson
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
| | - Matthew J Sweet
- Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia.,Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, Australia
| | - Glen C Ulett
- School of Medical Science, and Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland, Australia.,Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland, Australia
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52
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Chaban B, Hughes HV, Beeby M. The flagellum in bacterial pathogens: For motility and a whole lot more. Semin Cell Dev Biol 2015; 46:91-103. [DOI: 10.1016/j.semcdb.2015.10.032] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 02/05/2023]
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53
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More than a locomotive organelle: flagella in Escherichia coli. Appl Microbiol Biotechnol 2015; 99:8883-90. [DOI: 10.1007/s00253-015-6946-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/17/2015] [Accepted: 08/20/2015] [Indexed: 10/23/2022]
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54
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Shen J, Rump L, Ju W, Shao J, Zhao S, Brown E, Meng J. Virulence characterization of non-O157 Shiga toxin-producing Escherichia coli isolates from food, humans and animals. Food Microbiol 2015; 50:20-7. [DOI: 10.1016/j.fm.2015.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/10/2015] [Accepted: 02/12/2015] [Indexed: 10/24/2022]
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55
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Connolly JPR, Finlay BB, Roe AJ. From ingestion to colonization: the influence of the host environment on regulation of the LEE encoded type III secretion system in enterohaemorrhagic Escherichia coli. Front Microbiol 2015; 6:568. [PMID: 26097473 PMCID: PMC4456613 DOI: 10.3389/fmicb.2015.00568] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/24/2015] [Indexed: 12/21/2022] Open
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) binds to host tissue and intimately attaches to intestinal cells using a dedicated type III secretion system (T3SS). This complex multi-protein organelle is encoded within a large pathogenicity island called the locus of enterocyte effacement (LEE), which is subject to extensive regulatory control. Over the past 15 years we have gained a wealth of knowledge concerning how the LEE is regulated transcriptionally by specific, global and phage encoded regulators. More recently, significant advances have been made in our understanding of how specific signals, including host or microbiota derived metabolic products and various nutrient sources, can affect how the LEE-encoded T3SS is regulated. In this review we discuss regulation of the LEE, focusing on how these physiologically relevant signals are sensed and how they affect the expression of this major virulence factor. The implications for understanding the disease process by specific regulatory mechanisms are also discussed.
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Affiliation(s)
- James P R Connolly
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
| | - B Brett Finlay
- Michael Smith Laboratories, University of British Columbia , Vancouver, BC, Canada
| | - Andrew J Roe
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
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56
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McNeilly TN, Mitchell MC, Corbishley A, Nath M, Simmonds H, McAteer SP, Mahajan A, Low JC, Smith DGE, Huntley JF, Gally DL. Optimizing the Protection of Cattle against Escherichia coli O157:H7 Colonization through Immunization with Different Combinations of H7 Flagellin, Tir, Intimin-531 or EspA. PLoS One 2015; 10:e0128391. [PMID: 26020530 PMCID: PMC4447243 DOI: 10.1371/journal.pone.0128391] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 04/24/2015] [Indexed: 11/19/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are important human pathogens, causing hemorrhagic colitis and hemolytic uraemic syndrome in humans. E. coli O157:H7 is the most common serotype associated with EHEC infections worldwide, although other non-O157 serotypes cause life-threatening infections. Cattle are a main reservoir of EHEC and intervention strategies aimed at limiting EHEC excretion from cattle are predicted to lower the risk of human infection. We have previously shown that immunization of calves with recombinant versions of the type III secretion system (T3SS)-associated proteins EspA, intimin and Tir from EHEC O157:H7 significantly reduced shedding of EHEC O157 from experimentally-colonized calves, and that protection could be augmented by the addition of H7 flagellin to the vaccine formulation. The main aim of the present study was to optimize our current EHEC O157 subunit vaccine formulations by identifying the key combinations of these antigens required for protection. A secondary aim was to determine if vaccine-induced antibody responses exhibited cross-reactive potential with antigens from other EHEC serotypes. Immunization with EspA, intimin and Tir resulted in a reduction in mean EHEC O157 shedding following challenge, but not the mean proportion of calves colonized. Removal of Tir resulted in more prolonged shedding compared with all other groups, whereas replacement of Tir with H7 flagellin resulted in the highest levels of protection, both in terms of reducing both mean EHEC O157 shedding and the proportion of colonized calves. Immunization of calves with recombinant EHEC O157 EspA, intimin and Tir resulted in the generation of antibodies capable of cross-reacting with antigens from non-O157 EHEC serotypes, suggesting that immunization with these antigens may provide a degree of cross-protection against other EHEC serotypes. Further studies are now required to test the efficacy of these vaccines in the field, and to formally test the cross-protective potential of the vaccines against other non-O157 EHEC.
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Affiliation(s)
- Tom N. McNeilly
- Moredun Research Institute, Edinburgh, United Kingdom
- * E-mail:
| | | | - Alexander Corbishley
- Moredun Research Institute, Edinburgh, United Kingdom
- Division of Immunity and Infection, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Mintu Nath
- Biomathematics and Statistics Scotland, Edinburgh, United Kingdom
| | - Hannah Simmonds
- Division of Immunity and Infection, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Sean P. McAteer
- Division of Immunity and Infection, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - Arvind Mahajan
- Division of Immunity and Infection, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - J. Christopher Low
- Division of Immunity and Infection, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
| | - David G. E. Smith
- Moredun Research Institute, Edinburgh, United Kingdom
- Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | | | - David L. Gally
- Division of Immunity and Infection, The Roslin Institute, University of Edinburgh, Edinburgh, United Kingdom
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57
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Chemical communication in the gut: Effects of microbiota-generated metabolites on gastrointestinal bacterial pathogens. Anaerobe 2015; 34:106-15. [PMID: 25958185 DOI: 10.1016/j.anaerobe.2015.05.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 04/24/2015] [Accepted: 05/04/2015] [Indexed: 01/27/2023]
Abstract
Gastrointestinal pathogens must overcome many obstacles in order to successfully colonize a host, not the least of which is the presence of the gut microbiota, the trillions of commensal microorganisms inhabiting mammals' digestive tracts, and their products. It is well established that a healthy gut microbiota provides its host with protection from numerous pathogens, including Salmonella species, Clostridium difficile, diarrheagenic Escherichia coli, and Vibrio cholerae. Conversely, pathogenic bacteria have evolved mechanisms to establish an infection and thrive in the face of fierce competition from the microbiota for space and nutrients. Here, we review the evidence that gut microbiota-generated metabolites play a key role in determining the outcome of infection by bacterial pathogens. By consuming and transforming dietary and host-produced metabolites, as well as secreting primary and secondary metabolites of their own, the microbiota define the chemical environment of the gut and often determine specific host responses. Although most gut microbiota-produced metabolites are currently uncharacterized, several well-studied molecules made or modified by the microbiota are known to affect the growth and virulence of pathogens, including short-chain fatty acids, succinate, mucin O-glycans, molecular hydrogen, secondary bile acids, and the AI-2 quorum sensing autoinducer. We also discuss challenges and possible approaches to further study of the chemical interplay between microbiota and gastrointestinal pathogens.
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58
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Kerner K, Bridger PS, Köpf G, Fröhlich J, Barth S, Willems H, Bauerfeind R, Baljer G, Menge C. Evaluation of biological safety in vitro and immunogenicity in vivo of recombinant Escherichia coli Shiga toxoids as candidate vaccines in cattle. Vet Res 2015; 46:38. [PMID: 25889651 PMCID: PMC4391668 DOI: 10.1186/s13567-015-0175-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/26/2015] [Indexed: 12/18/2022] Open
Abstract
Cattle are the most important reservoir for enterohemorrhagic Escherichia coli (EHEC), a subset of shigatoxigenic E. coli (STEC) capable of causing life-threatening infectious diseases in humans. In cattle, Shiga toxins (Stx) suppress the immune system thereby promoting long-term STEC shedding. First infections of animals at calves’ age coincide with the lack of Stx-specific antibodies. We hypothesize that vaccination of calves against Shiga toxins prior to STEC infection may help to prevent the establishment of a persistent type of infection. The objectives of this study were to generate recombinant Shiga toxoids (rStx1mut & rStx2mut) by site-directed mutagenesis and to assess their immunomodulatory, antigenic, and immunogenic properties. Cultures of bovine primary immune cells were used as test systems. In ileal intraepithelial lymphocytes both, recombinant wild type Stx1 (rStx1WT) and rStx2WT significantly induced transcription of IL-4 mRNA. rStx1WT and rStx2WT reduced the expression of Stx-receptor CD77 (syn. Globotriaosylceramide, Gb3) on B and T cells from peripheral blood and of CD14 on monocyte-derived macrophages. At the same concentrations, rStx1mut and rStx2mut exhibited neither of these effects. Antibodies in sera of cattle naturally infected with STEC recognized the rStxmut toxoids equally well as the recombinant wild type toxins. Immunization of calves with rStx1mut plus rStx2mut led to induction of antibodies neutralizing Stx1 and Stx2. While keeping their antigenicity and immunogenicity recombinant Shiga toxoids are devoid of the immunosuppressive properties of the corresponding wild type toxins in cattle and candidate vaccines to mitigate long-term STEC shedding by the reservoir host.
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Affiliation(s)
- Katharina Kerner
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany.
| | - Philip S Bridger
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany.
| | - Gabriele Köpf
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany.
| | - Julia Fröhlich
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany.
| | - Stefanie Barth
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany. .,Current Address: Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Naumburger Str. 96a, 07743, Jena, Germany.
| | - Hermann Willems
- Clinic for Ruminants and Swine (Internal Medicine & Surgery), Justus Liebig University, Giessen, Germany.
| | - Rolf Bauerfeind
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany.
| | - Georg Baljer
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany.
| | - Christian Menge
- Institute of Hygiene and Infectious Diseases of Animals, Justus Liebig University, Frankfurter Str. 85-89, 35392, Giessen, Germany. .,Current Address: Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Naumburger Str. 96a, 07743, Jena, Germany.
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59
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Pradel N, Etienne-Mesmin L, Thévenot J, Cordonnier C, Blanquet-Diot S, Livrelli V. In vitro adhesion properties of Shiga toxin-producing Escherichia coli isolated from cattle, food, and humans. Front Microbiol 2015; 6:156. [PMID: 25774152 PMCID: PMC4343011 DOI: 10.3389/fmicb.2015.00156] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/10/2015] [Indexed: 11/13/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) are able to cause serious illnesses ranging from diarrhea to hemorrhagic colitis and hemolytic-uremic syndrome (HUS). These bacteria colonize the digestive tract of humans and produce Shiga-toxins, which are considered to be essential for virulence and are crucial in lethal infection. Colon colonization is supposed to be a determinant step in the development of the infection, but the virulence traits that mediate this step are unclear. We analyzed the ability of 256 STEC strains belonging to seropathotype A (the most virulent O157:H7 serotype) to seropathotype E (not involved in human disease) to adhere to HEp-2, HCT-8, and T84 cell lines. Of the 256 STEC tested most (82%) were non-adherent in our assays. The adhesion levels were globally low and were not related to pathogenicity, although the highest levels were associated to O26:H11 and O103:H2 strains of seropathotype B (associated with HUS but less commonly than serotype O157:H7), possessing both the eae and toxB genes.
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Affiliation(s)
- Nathalie Pradel
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, 'Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte' UMR INSERM/Université d'Auvergne U1071 USC-INRA 2018, Clermont Université - Université d'Auvergne Clermont-Ferrand, France
| | - Lucie Etienne-Mesmin
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, 'Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte' UMR INSERM/Université d'Auvergne U1071 USC-INRA 2018, Clermont Université - Université d'Auvergne Clermont-Ferrand, France ; Centre de Recherche en Nutrition Humaine Auvergne, EA-4678 CIDAM, 'Conception Ingénierie et Développement de l'Aliment et du Médicament', Clermont Université - Université d'Auvergne Clermont-Ferrand, France
| | - Jonathan Thévenot
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, 'Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte' UMR INSERM/Université d'Auvergne U1071 USC-INRA 2018, Clermont Université - Université d'Auvergne Clermont-Ferrand, France ; Centre de Recherche en Nutrition Humaine Auvergne, EA-4678 CIDAM, 'Conception Ingénierie et Développement de l'Aliment et du Médicament', Clermont Université - Université d'Auvergne Clermont-Ferrand, France
| | - Charlotte Cordonnier
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, 'Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte' UMR INSERM/Université d'Auvergne U1071 USC-INRA 2018, Clermont Université - Université d'Auvergne Clermont-Ferrand, France ; Centre de Recherche en Nutrition Humaine Auvergne, EA-4678 CIDAM, 'Conception Ingénierie et Développement de l'Aliment et du Médicament', Clermont Université - Université d'Auvergne Clermont-Ferrand, France
| | - Stéphanie Blanquet-Diot
- Centre de Recherche en Nutrition Humaine Auvergne, EA-4678 CIDAM, 'Conception Ingénierie et Développement de l'Aliment et du Médicament', Clermont Université - Université d'Auvergne Clermont-Ferrand, France
| | - Valérie Livrelli
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, 'Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte' UMR INSERM/Université d'Auvergne U1071 USC-INRA 2018, Clermont Université - Université d'Auvergne Clermont-Ferrand, France ; Unité de Recherche M2iSH, Faculté de Pharmacie, CHU Clermont-Ferrand, Service Bactériologie Mycologie Parasitologie Clermont-Ferrand, France
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60
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Abstract
Adhesins are a group of proteins in enterohemorrhagic Escherichia coli (EHEC) that are involved in the attachment or colonization of this pathogen to abiotic (plastic or steel) and biological surfaces, such as those found in bovine and human intestines. This review provides the most up-to-date information on these essential adhesion factors, summarizing important historical discoveries and analyzing the current and future state of this research. In doing so, the proteins intimin and Tir are discussed in depth, especially regarding their role in the development of attaching and effacing lesions and in EHEC virulence. Further, a series of fimbrial proteins (Lpf1, Lpf2, curli, ECP, F9, ELF, Sfp, HCP, and type 1 fimbriae) are also described, emphasizing their various contributions to adherence and colonization of different surfaces and their potential use as genetic markers in detection and classification of different EHEC serotypes. This review also discusses the role of several autotransporter proteins (EhaA-D, EspP, Saa and Sab, and Cah), as well as other proteins associated with adherence, such as flagella, EibG, Iha, and OmpA. While these proteins have all been studied to varying degrees, all of the adhesins summarized in this chapter have been linked to different stages of the EHEC life cycle, making them good targets for the development of more effective diagnostics and therapeutics.
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Affiliation(s)
- Brian D. McWilliams
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555. USA
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, 77555. USA
- Department of Pathology and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, 77555. USA
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61
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Rossez Y, Wolfson EB, Holmes A, Gally DL, Holden NJ. Bacterial flagella: twist and stick, or dodge across the kingdoms. PLoS Pathog 2015; 11:e1004483. [PMID: 25590430 PMCID: PMC4295861 DOI: 10.1371/journal.ppat.1004483] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The flagellum organelle is an intricate multiprotein assembly best known for its rotational propulsion of bacteria. However, recent studies have expanded our knowledge of other functions in pathogenic contexts, particularly adherence and immune modulation, e.g., for Salmonella enterica, Campylobacter jejuni, Pseudomonas aeruginosa, and Escherichia coli. Flagella-mediated adherence is important in host colonisation for several plant and animal pathogens, but the specific interactions that promote flagella binding to such diverse host tissues has remained elusive. Recent work has shown that the organelles act like probes that find favourable surface topologies to initiate binding. An emerging theme is that more general properties, such as ionic charge of repetitive binding epitopes and rotational force, allow interactions with plasma membrane components. At the same time, flagellin monomers are important inducers of plant and animal innate immunity: variation in their recognition impacts the course and outcome of infections in hosts from both kingdoms. Bacteria have evolved different strategies to evade or even promote this specific recognition, with some important differences shown for phytopathogens. These studies have provided a wider appreciation of the functions of bacterial flagella in the context of both plant and animal reservoirs.
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Affiliation(s)
- Yannick Rossez
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, United Kingdom
| | - Eliza B. Wolfson
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, United Kingdom
| | - Ashleigh Holmes
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, United Kingdom
| | - David L. Gally
- Division of Infection and Immunity, The Roslin Institute, University of Edinburgh, Easter Bush, United Kingdom
| | - Nicola J. Holden
- Cellular and Molecular Sciences, James Hutton Institute, Dundee, United Kingdom
- * E-mail:
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62
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Abstract
ABSTRACT
Human infection with Shiga toxin-producing
Escherichia coli
O157:H7 (STEC O157) is relatively rare, but the consequences can be serious, especially in the very young and the elderly. Efforts to control the flow of STEC O157 during beef processing have meaningfully reduced the incidence of human STEC O157 infection, particularly prior to 2005. Unfortunately, despite early progress, the incidence of STEC O157 infection has not changed meaningfully or statistically in recent years, suggesting that additional actions, for example, targeting the cattle reservoir, are necessary to further reduce STEC O157 illness. Ideally, preharvest interventions against STEC O157 should reduce the likelihood that cattle carry the organism, have practical application within the beef production system, and add sufficient value to the cattle to offset the cost of the intervention. A number of STEC O157 antigens are being investigated as potential vaccine targets. Some vaccine products have demonstrated efficacy to reduce the prevalence of cattle carrying STEC O157 by making the gut unfavorable to colonization. However, in conditions of natural exposure, efficacy afforded by vaccination depends on how the products are used to control environmental transmission within groups of cattle and throughout the production system. Although cattle vaccines against STEC O157 have gained either full or preliminary regulatory approval in Canada and the United States, widespread use by cattle feeders is unlikely until there is an economic signal to indicate that cattle vaccinated against STEC O157 are valued over other cattle.
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63
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Strain-dependent cellular immune responses in cattle following Escherichia coli O157:H7 colonization. Infect Immun 2014; 82:5117-31. [PMID: 25267838 DOI: 10.1128/iai.02462-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic diarrhea and potentially fatal renal failure in humans. Ruminants are considered to be the primary reservoir for human infection. Vaccines that reduce shedding in cattle are only partially protective, and their underlying protective mechanisms are unknown. Studies investigating the response of cattle to colonization generally focus on humoral immunity, leaving the role of cellular immunity unclear. To inform future vaccine development, we studied the cellular immune responses of cattle during EHEC O157:H7 colonization. Calves were challenged either with a phage type 21/28 (PT21/28) strain possessing the Shiga toxin 2a (Stx2a) and Stx2c genes or with a PT32 strain possessing the Stx2c gene only. T-helper cell-associated transcripts at the terminal rectum were analyzed by reverse transcription-quantitative PCR (RT-qPCR). Induction of gamma interferon (IFN-γ) and T-bet was observed with peak expression of both genes at 7 days in PT32-challenged calves, while upregulation was delayed, peaking at 21 days, in PT21/28-challenged calves. Cells isolated from gastrointestinal lymph nodes demonstrated antigen-specific proliferation and IFN-γ release in response to type III secreted proteins (T3SPs); however, responsiveness was suppressed in cells isolated from PT32-challenged calves. Lymph node cells showed increased expression of the proliferation marker Ki67 in CD4(+) T cells from PT21/28-challenged calves, NK cells from PT32-challenged calves, and CD8(+) and γδ T cells from both PT21/28- and PT32-challenged calves following ex vivo restimulation with T3SPs. This study demonstrates that cattle mount cellular immune responses during colonization with EHEC O157:H7, the temporality of which is strain dependent, with further evidence of strain-specific immunomodulation.
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64
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Abstract
ABSTRACT
Coordinated expression of enterohemorrhagic
Escherichia coli
virulence genes enables the bacterium to cause hemorrhagic colitis and the complication known as hemolytic-uremic syndrome. Horizontally acquired genes and those common to
E. coli
contribute to the disease process, and increased virulence gene expression is correlated with more severe disease in humans. Researchers have gained considerable knowledge about how the type III secretion system, secreted effectors, adhesin molecules, and the Shiga toxins are regulated by environmental signals and multiple genetic pathways. Also emergent from the data is an understanding of how enterohemorrhagic
E. coli
regulates response to acid stress, the role of flagellar motility, and how passage through the human host and bovine intestinal tract causes disease and supports carriage in the cattle reservoir, respectively. Particularly exciting areas of discovery include data suggesting how expression of the myriad effectors is coordinately regulated with their cognate type III secretion system and how virulence is correlated with bacterial metabolism and gut physiology.
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65
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Beckham KSH, Connolly JPR, Ritchie JM, Wang D, Gawthorne JA, Tahoun A, Gally DL, Burgess K, Burchmore RJ, Smith BO, Beatson SA, Byron O, Wolfe AJ, Douce GR, Roe AJ. The metabolic enzyme AdhE controls the virulence of Escherichia coli O157:H7. Mol Microbiol 2014; 93:199-211. [PMID: 24846743 PMCID: PMC4249723 DOI: 10.1111/mmi.12651] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2014] [Indexed: 12/02/2022]
Abstract
Classical studies have focused on the role that individual regulators play in controlling virulence gene expression. An emerging theme, however, is that bacterial metabolism also plays a key role in this process. Our previous work identified a series of proteins that were implicated in the regulation of virulence. One of these proteins was AdhE, a bi-functional acetaldehyde-CoA dehydrogenase and alcohol dehydrogenase. Deletion of its gene (adhE) resulted in elevated levels of extracellular acetate and a stark pleiotropic phenotype: strong suppression of the Type Three Secretion System (T3SS) and overexpression of non-functional flagella. Correspondingly, the adhE mutant bound poorly to host cells and was unable to swim. Furthermore, the mutant was significantly less virulent than its parent when tested in vivo, which supports the hypothesis that attachment and motility are central to the colonization process. The molecular basis by which AdhE affects virulence gene regulation was found to be multifactorial, involving acetate-stimulated transcription of flagella expression and post-transcriptional regulation of the T3SS through Hfq. Our study reveals fascinating insights into the links between bacterial physiology, the expression of virulence genes, and the underlying molecular mechanism mechanisms by which these processes are regulated.
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Affiliation(s)
- Katherine S H Beckham
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - James P R Connolly
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - Jennifer M Ritchie
- Faculty of Health and Medical Sciences, University of SurreyGuildford, GU2 7XH, UK
| | - Dai Wang
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
- † Present address: School of Public Health, Xiamen University South Xiangan Rd., Xiamen, Fujian Province, China
| | - Jayde A Gawthorne
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - Amin Tahoun
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
- Faculty of Health and Medical Sciences, University of SurreyGuildford, GU2 7XH, UK
| | - David L Gally
- School of Life Sciences, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - Karl Burgess
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - Richard J Burchmore
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - Brian O Smith
- Immunity and Infection Division, The Roslin Institute and R(D)SVS, The University of EdinburghEaster Bush, Midlothian, EH25 9RG, UK
| | - Scott A Beatson
- Faculty of Veterinary Medicine, Kafrelsheikh University33516, Kafr el-Sheikh, Egypt
| | - Olwyn Byron
- School of Chemistry and Molecular Biosciences and Australian Infectious Diseases Research Centre, University of QueenslandSt. Lucia, Qld, 4072, Australia
| | - Alan J Wolfe
- Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine2160 S. First Ave., Bldg. 105, Maywood, IL, 60153, USA
| | - Gillian R Douce
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
| | - Andrew J Roe
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of GlasgowGlasgow, G12 8TA, UK
- *For correspondence. E-mail ; Tel. (+44) 141 3302980; Fax (+44) 141 330 2981
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Escherichia coli strains expressing H12 antigens demonstrate an increased ability to attach to abiotic surfaces as compared with E. coli strains expressing H7 antigens. Colloids Surf B Biointerfaces 2014; 119:90-8. [PMID: 24880987 DOI: 10.1016/j.colsurfb.2014.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 04/10/2014] [Accepted: 04/13/2014] [Indexed: 11/21/2022]
Abstract
The role of Escherichia coli H antigens in hydrophobicity and attachment to glass, Teflon and stainless steel (SS) surfaces was investigated through construction of fliC knockout mutants in E. coli O157:H7, O1:H7 and O157:H12. Loss of FliC(H12) in E. coli O157:H12 decreased attachment to glass, Teflon and stainless steel surfaces (p<0.05). Complementing E. coli O157:H12 ΔfliC(H12) with cloned wildtype (wt) fliC(H12) restored attachment to wt levels. The loss of FliCH7 in E. coli O157:H7 and O1:H7 did not always alter attachment (p>0.05), but complementation with cloned fliC(H12), as opposed to cloned fliCH7, significantly increased attachment for both strains compared with wt counterparts (p<0.05). Hydrophobicity determined using bacterial adherence to hydrocarbons and contact angle measurements differed with fliC expression but was not correlated to the attachment to materials included in this study. Purified FliC was used to functionalise silicone nitride atomic force microscopy probes, which were used to measure adhesion forces between FliC and substrates. Although no significant difference in adhesion force was observed between FliC(H12) and FliCH7 probes, differences in force curves suggest different mechanism of attachment for FliC(H12) compared with FliCH7. These results indicate that E. coli strains expressing flagellar H12 antigens have an increased ability to attach to certain abiotic surfaces compared with E. coli strains expressing H7 antigens.
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Kainulainen V, Korhonen TK. Dancing to another tune-adhesive moonlighting proteins in bacteria. BIOLOGY 2014; 3:178-204. [PMID: 24833341 PMCID: PMC4009768 DOI: 10.3390/biology3010178] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 02/26/2014] [Accepted: 02/27/2014] [Indexed: 02/08/2023]
Abstract
Biological moonlighting refers to proteins which express more than one function. Moonlighting proteins occur in pathogenic and commensal as well as in Gram-positive and Gram-negative bacteria. The canonical functions of moonlighting proteins are in essential cellular processes, i.e., glycolysis, protein synthesis, chaperone activity, and nucleic acid stability, and their moonlighting functions include binding to host epithelial and phagocytic cells, subepithelia, cytoskeleton as well as to mucins and circulating proteins of the immune and hemostatic systems. Sequences of the moonlighting proteins do not contain known motifs for surface export or anchoring, and it has remained open whether bacterial moonlighting proteins are actively secreted to the cell wall or whether they are released from traumatized cells and then rebind onto the bacteria. In lactobacilli, ionic interactions with lipoteichoic acids and with cell division sites are important for surface localization of the proteins. Moonlighting proteins represent an abundant class of bacterial adhesins that are part of bacterial interactions with the environment and in responses to environmental changes. Multifunctionality in bacterial surface proteins appears common: the canonical adhesion proteins fimbriae express also nonadhesive functions, whereas the mobility organelles flagella as well as surface proteases express adhesive functions.
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Affiliation(s)
- Veera Kainulainen
- Department of Veterinary Biosciences, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
| | - Timo K Korhonen
- General Microbiology, Department of Biosciences, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland.
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Sharma VK, Casey TA. Determining the relative contribution and hierarchy of hha and qseBC in the regulation of flagellar motility of Escherichia coli O157:H7. PLoS One 2014; 9:e85866. [PMID: 24465756 PMCID: PMC3897532 DOI: 10.1371/journal.pone.0085866] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 12/06/2013] [Indexed: 11/18/2022] Open
Abstract
In recent studies, we demonstrated that a deletion of hha caused increased secretion of locus of enterocyte encoded adherence proteins and reduced motility of enterohemorrhagic Escherichia coli (EHEC) O157:H7. In addition to the importance of hha in positive regulation of motility, a two-component quorum sensing pathway encoded by the qseBC genes has been shown to activate bacterial motility in response to mammalian stress hormones epinephrine and norepinephrine as well as bacterially produced autoinducer-3. In this study, we compared regulatory contribution and hierarchy of hha, a member of the Hha/YmoA family of nucleoid-associated proteins, to that of qseBC in the expression of EHEC O157:H7 motility. Since norepinephrine affects motility of EHEC O157:H7 through a qseBC-encoded two-component quorum sensing signaling, we also determined whether the hha-mediated regulation of motility is affected by norepinephrine and whether this effect is qseBC dependent. We used single (Δhha or ΔqseC) and double (Δhha ΔqseC) deletion mutants to show that hha exerts a greater positive regulatory effect in comparison to qseBC on the expression of motility by EHEC O157:H7. We also show that Hha is hierarchically superior in transcriptional regulation of motility than QseBC because transcription of qseC was significantly reduced in the hha deletion mutant compared to that in the parental and the hha-complemented mutant strains. These results suggest that hha regulates motility of EHEC O157:H7 directly as well as indirectly by controlling the transcription of qseBC.
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Affiliation(s)
- Vijay K. Sharma
- Food Safety and Enteric Pathogens Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, United States of America
- * E-mail:
| | - Thomas A. Casey
- Food Safety and Enteric Pathogens Research Unit, United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Ames, Iowa, United States of America
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Escherichia coli O157:H7 lacking the qseBC-encoded quorum-sensing system outcompetes the parental strain in colonization of cattle intestines. Appl Environ Microbiol 2014; 80:1882-92. [PMID: 24413602 DOI: 10.1128/aem.03198-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The qseBC-encoded quorum-sensing system regulates the motility of Escherichia coli O157:H7 in response to bacterial autoinducer 3 (AI-3) and the mammalian stress hormones epinephrine (E) and norepinephrine (NE). The qseC gene encodes a sensory kinase that autophosphorylates in response to AI-3, E, or NE and subsequently phosphorylates its cognate response regulator QseB. In the absence of QseC, QseB downregulates bacterial motility and virulence in animal models. In this study, we found that 8- to 10-month-old calves orally inoculated with a mixture of E. coli O157:H7 and its isogenic qseBC mutant showed significantly higher fecal shedding of the qseBC mutant. In vitro analysis revealed similar growth profiles and motilities of the qseBC mutant and the parental strain in the presence or absence of NE. The magnitudes of the response to NE and expression of flagellar genes flhD and fliC were also similar for the qseBC mutant and the parental strain. The expression of ler (a positive regulator of the locus of enterocyte effacement [LEE]), the ler-regulated espA gene, and the csgA gene (encoding curli fimbriae) was increased in the qseBC mutant compared to the parental strain. On the other hand, growth, motility, and transcription of flhD, fliC, ler, espA, and csgA were significantly reduced in the qseBC mutant complemented with a plasmid-cloned copy of the qseBC genes. Thus, in vitro motility and gene expression data indicate that the near-parental level of motility, ability to respond to NE, and enhanced expression of LEE and curli genes might in part be responsible for increased colonization and fecal shedding of the qseBC mutant in calves.
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70
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Rossez Y, Holmes A, Wolfson EB, Gally DL, Mahajan A, Pedersen HL, Willats WG, Toth IK, Holden NJ. Flagella interact with ionic plant lipids to mediate adherence of pathogenicEscherichia colito fresh produce plants. Environ Microbiol 2013; 16:2181-95. [DOI: 10.1111/1462-2920.12315] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/08/2013] [Indexed: 12/21/2022]
Affiliation(s)
- Yannick Rossez
- Cellular and Molecular Sciences; James Hutton Institute; Dundee Scotland UK
| | - Ashleigh Holmes
- Cellular and Molecular Sciences; James Hutton Institute; Dundee Scotland UK
| | - Eliza B. Wolfson
- The Roslin Institute Division of Infection and Immunity; University of Edinburgh, R(D)SVS; Edinburgh EH25 9RG UK
| | - David L. Gally
- The Roslin Institute Division of Infection and Immunity; University of Edinburgh, R(D)SVS; Edinburgh EH25 9RG UK
| | - Arvind Mahajan
- The Roslin Institute Division of Infection and Immunity; University of Edinburgh, R(D)SVS; Edinburgh EH25 9RG UK
| | | | - William G.T. Willats
- Department of Plant Biology and Biotechnology; University of Copenhagen; Denmark
| | - Ian K. Toth
- Cellular and Molecular Sciences; James Hutton Institute; Dundee Scotland UK
| | - Nicola J. Holden
- Cellular and Molecular Sciences; James Hutton Institute; Dundee Scotland UK
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71
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The role of the bacterial flagellum in adhesion and virulence. BIOLOGY 2013; 2:1242-67. [PMID: 24833223 PMCID: PMC4009794 DOI: 10.3390/biology2041242] [Citation(s) in RCA: 345] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/27/2013] [Accepted: 09/30/2013] [Indexed: 12/11/2022]
Abstract
The bacterial flagellum is a complex apparatus assembled of more than 20 different proteins. The flagellar basal body traverses the cell wall, whereas the curved hook connects the basal body to the whip-like flagellar filament that protrudes several µm from the bacterial cell. The flagellum has traditionally been regarded only as a motility organelle, but more recently it has become evident that flagella have a number of other biological functions. The major subunit, flagellin or FliC, of the flagellum plays a well-documented role in innate immunity and as a dominant antigen of the adaptive immune response. Importantly, flagella have also been reported to function as adhesins. Whole flagella have been indicated as significant in bacterial adhesion to and invasion into host cells. In various pathogens, e.g., Escherichia coli, Pseudomonas aeruginosa and Clostridium difficile, flagellin and/or the distally located flagellar cap protein have been reported to function as adhesins. Recently, FliC of Shiga-toxigenic E. coli was shown to be involved in cellular invasion via lipid rafts. Here, we examine the latest or most important findings regarding flagellar adhesive and invasive properties, especially focusing on the flagellum as a potential virulence factor.
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72
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Chagnot C, Zorgani MA, Astruc T, Desvaux M. Proteinaceous determinants of surface colonization in bacteria: bacterial adhesion and biofilm formation from a protein secretion perspective. Front Microbiol 2013; 4:303. [PMID: 24133488 PMCID: PMC3796261 DOI: 10.3389/fmicb.2013.00303] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/22/2013] [Indexed: 01/30/2023] Open
Abstract
Bacterial colonization of biotic or abiotic surfaces results from two quite distinct physiological processes, namely bacterial adhesion and biofilm formation. Broadly speaking, a biofilm is defined as the sessile development of microbial cells. Biofilm formation arises following bacterial adhesion but not all single bacterial cells adhering reversibly or irreversibly engage inexorably into a sessile mode of growth. Among molecular determinants promoting bacterial colonization, surface proteins are the most functionally diverse active components. To be present on the bacterial cell surface, though, a protein must be secreted in the first place. Considering the close association of secreted proteins with their cognate secretion systems, the secretome (which refers both to the secretion systems and their protein substrates) is a key concept to apprehend the protein secretion and related physiological functions. The protein secretion systems are here considered in light of the differences in the cell-envelope architecture between diderm-LPS (archetypal Gram-negative), monoderm (archetypal Gram-positive) and diderm-mycolate (archetypal acid-fast) bacteria. Besides, their cognate secreted proteins engaged in the bacterial colonization process are regarded from single protein to supramolecular protein structure as well as the non-classical protein secretion. This state-of-the-art on the complement of the secretome (the secretion systems and their cognate effectors) involved in the surface colonization process in diderm-LPS and monoderm bacteria paves the way for future research directions in the field.
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Affiliation(s)
- Caroline Chagnot
- UR454 Microbiologie, INRA Saint-Genès Champanelle, France ; UR370 Qualité des Produits Animaux, INRA Saint-Genès Champanelle, France
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Xu Y, Xu X, Lan R, Xiong Y, Ye C, Ren Z, Liu L, Zhao A, Wu LF, Xu J. An O island 172 encoded RNA helicase regulates the motility of Escherichia coli O157:H7. PLoS One 2013; 8:e64211. [PMID: 23785398 PMCID: PMC3681947 DOI: 10.1371/journal.pone.0064211] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/10/2013] [Indexed: 12/28/2022] Open
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of zoonotic food- and water-borne intestinal infections worldwide with clinical consequences ranging from mild diarrhoea to hemolytic uraemic syndrome. The genome of EHEC O157:H7 contains many regions of unique DNA that are referred to as O islands including the Shiga toxin prophages and pathogenicity islands encoding key virulence factors. However many of these O islands are of unknown function. In this study, genetic analysis was conducted on OI-172 which is a 44,434 bp genomic island with 27 open reading frames. Comparative genome analysis showed that O1-72 is a composite island with progressive gain of genes since O157:H7 evolved from its ancestral O55:H7. A partial OI-172 island was also found in 2 unrelated E. coli strains and 2 Salmonella strains. OI-172 encodes several putative helicases, one of which (Z5898) is a putative DEAH box RNA helicase. To investigate the function of Z5898, a deletion mutant (EDL933ΔZ5898) was constructed in the O157:H7 strain EDL933. Comparative proteomic analysis of the mutant with the wild-type EDL933 found that flagellin was down-regulated in the Z5898 mutant. Motility assay showed that EDL933ΔZ5898 migrated slower than the wild-type EDL933 and electron microscopy found no surface flagella. Quantitative reverse transcription PCR revealed that the fliC expression of EDL933ΔZ5898 was significantly lower while the expression of its upstream regulator gene, fliA, was not affected. Using a fliA and a fliC promoter - green fluorescent protein fusion contruct, Z5898 was found to affect only the fliC promoter activity. Therefore, Z5898 regulates the flagella based motility by exerting its effect on fliC. We conclude that OI-172 is a motility associated O island and hereby name it the MAO island.
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Affiliation(s)
- Yanmei Xu
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Xuefang Xu
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Yanwen Xiong
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Changyun Ye
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Zhihong Ren
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Li Liu
- Network Information Center, Institute of Microbiology, Chinese Academy of Sciences, Beijing, P R China
| | - Ailan Zhao
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
| | - Long-Fei Wu
- Laboratoire de Chimie Bactérienne, UPR9043, Université de la Méditerranée Aix-Marseille II, Institut de Microbiologie de la Méditerranée, CNRS, Marseille, France
| | - Jianguo Xu
- State Key Laboratory for Infectious Disease Prevention and Control (China CDC), Beijing, P R China
- National Institute of Communicable Diseases Control and Prevention and Control, Chinese Center for Disease Control and Prevention, Beijing, P R China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China
- * E-mail:
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Advances in the development of enterohemorrhagic Escherichia coli vaccines using murine models of infection. Vaccine 2013; 31:3229-35. [PMID: 23707170 DOI: 10.1016/j.vaccine.2013.05.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 01/22/2023]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) strains are food borne pathogens with importance in public health. EHEC colonizes the large intestine and causes diarrhea, hemorrhagic colitis and in some cases, life-threatening hemolytic-uremic syndrome (HUS) due to the production of Shiga toxins (Stx). The lack of effective clinical treatment, sequelae after infection and mortality rate in humans supports the urgent need of prophylactic approaches, such as development of vaccines. Shedding from cattle, the main EHEC reservoir and considered the principal food contamination source, has prompted the development of licensed vaccines that reduce EHEC colonization in ruminants. Although murine models do not fully recapitulate human infection, they are commonly used to evaluate EHEC vaccines and the immune/protective responses elicited in the host. Mice susceptibility differs depending of the EHEC inoculums; displaying different mortality rates and Stx-mediated renal damage. Therefore, several experimental protocols have being pursued in this model to develop EHEC-specific vaccines. Recent candidate vaccines evaluated include those composed of virulence factors alone or as fused-subunits, DNA-based, attenuated bacteria and bacterial ghosts. In this review, we summarize progress in the design and testing of EHEC vaccines and the use of different strategies for the evaluation of novel EHEC vaccines in the murine model.
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Zhou M, Duan Q, Zhu X, Guo Z, Li Y, Hardwidge PR, Zhu G. Both flagella and F4 fimbriae from F4ac+ enterotoxigenic Escherichia coli contribute to attachment to IPEC-J2 cells in vitro. Vet Res 2013; 44:30. [PMID: 23668601 PMCID: PMC3655849 DOI: 10.1186/1297-9716-44-30] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 04/12/2013] [Indexed: 12/04/2022] Open
Abstract
The role of flagella in the pathogenesis of F4ac+ Enterotoxigenic Escherichia coli (ETEC) mediated neonatal and post-weaning diarrhea (PWD) is not currently understood. We targeted the reference C83902 ETEC strain (O8:H19:F4ac+ LT+ STa+ STb+), to construct isogenic mutants in the fliC (encoding the major flagellin protein), motA (encoding the flagella motor), and faeG (encoding the major subunit of F4 fimbriae) genes. Both the ΔfliC and ΔfaeG mutants had a reduced ability to adhere to porcine intestinal epithelial IPEC-J2 cells. F4 fimbriae expression was significantly down-regulated after deleting fliC, which revealed that co-regulation exists between flagella and F4 fimbriae. However, there was no difference in adhesion between the ΔmotA mutant and its parent strain. These data demonstrate that both flagella and F4 fimbriae are required for efficient F4ac+ ETEC adhesion in vitro.
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Affiliation(s)
- Mingxu Zhou
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China.
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76
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Etcheverría AI, Padola NL. Shiga toxin-producing Escherichia coli: factors involved in virulence and cattle colonization. Virulence 2013; 4:366-72. [PMID: 23624795 PMCID: PMC3714128 DOI: 10.4161/viru.24642] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in humans. Outbreaks are linked to bovine food sources. STEC O157:H7 has been responsible for the most severe outbreaks worldwide. However, non-O157 serotypes have emerged as important enteric pathogens in several countries. The main virulence factor of STEC is the production of Shiga toxins 1 and 2. Additional virulence markers are a plasmid-encoded enterohemolysin (ehxA), an autoagglutinating adhesin (Saa), a catalase-peroxidase (katP), an extracellular serine protease (espP), a zinc metalloprotease (stcE), a subtilase cytotoxin (subAB), among others. Other virulence factors are intimin and adhesins that had a roll in the adherence of STEC to bovine colon. This review focuses on the virulence traits of STEC and especially on those related to the adhesion to bovine colon. The known of the interaction between STEC and the bovine host is crucial to develop strategies to control cattle colonization.
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Affiliation(s)
- Analía Inés Etcheverría
- Laboratorio de Imunoquímica y Biotecnología, Centro de Investigación Veterinaria de Tandil (CIVETAN), CONICET-CICPBA, Facultad de Ciencias Veterinarias, UNCPBA, Tandil, Argentina.
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77
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Hu J, Wang B, Fang X, Means WJ, McCormick RJ, Gomelsky M, Zhu MJ. c-di-GMP signaling regulates E. coli O157:H7 adhesion to colonic epithelium. Vet Microbiol 2013; 164:344-51. [PMID: 23528649 DOI: 10.1016/j.vetmic.2013.02.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/23/2013] [Accepted: 02/23/2013] [Indexed: 12/01/2022]
Abstract
Escherichia coli O157:H7 is an important foodborne pathogen that causes serious illness in humans at low infectious doses. The main source of infections is beef or greens contaminated with E. coli O157:H7 shed by cattle. Here we investigated the role of c-di-GMP-dependent signal transduction in cattle gut colonization of E. coli O157:H7. To manipulate intracellular c-di-GMP levels, we introduced into E. coli O157:H7 a c-di-GMP specific phosphodiesterase (PDE). Liquid chromatography tandem mass spectrometry analysis confirmed that in E. coli O157:H7, over-expression of PDE decreased c-di-GMP level. Consistent with the altered c-di-GMP level, PDE overexpression resulted in decreased biofilm formation in E. coli O157:H7. Furthermore, this diminished c-di-GMP levels reduced adhesion of E. coli O157:H7 to both cultured HT-29 cells and cattle colon explants. Consistently, mRNA levels of genes involved in adhesion were down-regulated including genes encoding E. coli common pili, long polar fimbriae 1, hemorrhagic coli pilus, as well as intimin and tir. We further observed decreased curli fimbriae synthesis in the strain with decreased c-di-GMP levels, which was supported by the reduction in the transcription of curli large subunit gene csgA and the curli expression regulator gene csgD. Genes for enterocyte effacement encoded regulator (Ler) and type III secretion system effectors, EspA and EspB, were also down-regulated. Collectively, data indicated that c-di-GMP signaling positively regulates E. coli O157:H7 intestinal epithelial cell and tissue colonization and expression of associated adhesion factors.
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Affiliation(s)
- Jia Hu
- Department of Animal Science, University of Wyoming, Laramie, WY 82071, USA
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78
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Dziva F, Hauser H, Connor TR, van Diemen PM, Prescott G, Langridge GC, Eckert S, Chaudhuri RR, Ewers C, Mellata M, Mukhopadhyay S, Curtiss R, Dougan G, Wieler LH, Thomson NR, Pickard DJ, Stevens MP. Sequencing and functional annotation of avian pathogenic Escherichia coli serogroup O78 strains reveal the evolution of E. coli lineages pathogenic for poultry via distinct mechanisms. Infect Immun 2013; 81:838-49. [PMID: 23275093 PMCID: PMC3584874 DOI: 10.1128/iai.00585-12] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/19/2012] [Indexed: 11/20/2022] Open
Abstract
Avian pathogenic Escherichia coli (APEC) causes respiratory and systemic disease in poultry. Sequencing of a multilocus sequence type 95 (ST95) serogroup O1 strain previously indicated that APEC resembles E. coli causing extraintestinal human diseases. We sequenced the genomes of two strains of another dominant APEC lineage (ST23 serogroup O78 strains χ7122 and IMT2125) and compared them to each other and to the reannotated APEC O1 sequence. For comparison, we also sequenced a human enterotoxigenic E. coli (ETEC) strain of the same ST23 serogroup O78 lineage. Phylogenetic analysis indicated that the APEC O78 strains were more closely related to human ST23 ETEC than to APEC O1, indicating that separation of pathotypes on the basis of their extraintestinal or diarrheagenic nature is not supported by their phylogeny. The accessory genome of APEC ST23 strains exhibited limited conservation of APEC O1 genomic islands and a distinct repertoire of virulence-associated loci. In light of this diversity, we surveyed the phenotype of 2,185 signature-tagged transposon mutants of χ7122 following intra-air sac inoculation of turkeys. This procedure identified novel APEC ST23 genes that play strain- and tissue-specific roles during infection. For example, genes mediating group 4 capsule synthesis were required for the virulence of χ7122 and were conserved in IMT2125 but absent from APEC O1. Our data reveal the genetic diversity of E. coli strains adapted to cause the same avian disease and indicate that the core genome of the ST23 lineage serves as a chassis for the evolution of E. coli strains adapted to cause avian or human disease via acquisition of distinct virulence genes.
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Affiliation(s)
- Francis Dziva
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Heidi Hauser
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Thomas R. Connor
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Pauline M. van Diemen
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Graham Prescott
- Enteric Bacterial Pathogens Laboratory, Institute for Animal Health, Compton, Berkshire, United Kingdom
| | - Gemma C. Langridge
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Sabine Eckert
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Roy R. Chaudhuri
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Christa Ewers
- Veterinary Faculty, Free University Berlin, Berlin, Germany
| | - Melha Mellata
- The Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Suman Mukhopadhyay
- The Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Roy Curtiss
- The Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Gordon Dougan
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | | | - Nicholas R. Thomson
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Derek J. Pickard
- Pathogen Genomics, The Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
| | - Mark P. Stevens
- Division of Infection and Immunity, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, United Kingdom
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79
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Vikram A, Jesudhasan PR, Pillai SD, Patil BS. Isolimonic acid interferes with Escherichia coli O157:H7 biofilm and TTSS in QseBC and QseA dependent fashion. BMC Microbiol 2012; 12:261. [PMID: 23153211 PMCID: PMC3562146 DOI: 10.1186/1471-2180-12-261] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 10/01/2012] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND E. coli O157:H7 (EHEC) is an important human pathogen. The antibiotic treatment of EHEC reportedly results in release of Shiga toxin and is therefore discouraged. Consequently, alternative preventive or therapeutic strategies for EHEC are required. The objective of the current study was to investigate the effect of citrus limonoids on cell-cell signaling, biofilm formation and type III secretion system in EHEC. RESULTS Isolimonic acid and ichangin were the most potent inhibitors of EHEC biofilm (IC25=19.7 and 28.3 μM, respectively) and adhesion to Caco-2 cells. The qPCR analysis revealed that isolimonic acid and ichangin repressed LEE encoded genes by ≈3 to 12 fold. In addition, flhDC was repressed by the two limonoids (≈3 to 7 fold). Further studies suggested that isolimonic acid interferes with AI-3/epinephrine activated cell-cell signaling pathway. Loss of biofilm inhibitory activity of isolimonic acid in ΔqseBC mutant, which could be restored upon complementation, suggested a dependence on functional QseBC. Additionally, overexpression of qseBC in wild type EHEC abated the inhibitory effect of isolimonic acid. Furthermore, the isolimonic acid failed to differentially regulate ler in ΔqseA mutant, while plasmid borne expression of qseA in ΔqseA background restored the repressive effect of isolimonic acid. CONCLUSIONS Altogether, results of study seem to suggest that isolimonic acid and ichangin are potent inhibitors of EHEC biofilm and TTSS. Furthermore, isolimonic acid appears to interfere with AI-3/epinephrine pathway in QseBC and QseA dependent fashion.
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Affiliation(s)
- Amit Vikram
- Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A &M University, Texas, 77843-2119, USA
| | - Palmy R Jesudhasan
- Food Safety & Environmental Microbiology Program, Texas A&M University, College Station, College Station, Texas, 77843-2472, USA
| | - Suresh D Pillai
- Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A &M University, Texas, 77843-2119, USA
- Food Safety & Environmental Microbiology Program, Texas A&M University, College Station, College Station, Texas, 77843-2472, USA
| | - Bhimanagouda S Patil
- Vegetable and Fruit Improvement Center, Department of Horticultural Sciences, Texas A &M University, Texas, 77843-2119, USA
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80
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Vande Walle K, Vanrompay D, Cox E. Bovine innate and adaptive immune responses against Escherichia coli O157:H7 and vaccination strategies to reduce faecal shedding in ruminants. Vet Immunol Immunopathol 2012; 152:109-20. [PMID: 23084625 DOI: 10.1016/j.vetimm.2012.09.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Enterohaemorrhagic E. coli (EHEC) O157:H7 is a zoonotic pathogen of worldwide importance causing foodborne infections with possibly life-threatening consequences in humans, such as haemorrhagic colitis and in a small percentage of zoonotic cases, haemolytic-uremic syndrome (HUS). Ruminants are an important reservoir of EHEC and human infections are most frequently associated with direct or indirect contact with ruminant faeces. A thorough understanding of the host-bacterium interaction in ruminants could lead to the development of novel interventions strategies, including innovative vaccines. This review aims to present the current knowledge regarding innate and adaptive immune responses in EHEC colonized ruminants. In addition, results on vaccination strategies in ruminants aiming at reduction of EHEC shedding are reviewed.
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Affiliation(s)
- Kris Vande Walle
- Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9860 Merelbeke, Belgium
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81
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Novel repressor of Escherichia coli O157:H7 motility encoded in the putative fimbrial cluster OI-1. J Bacteriol 2012; 194:5343-52. [PMID: 22843849 DOI: 10.1128/jb.01025-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O157:H7 is a gastrointestinal pathogen that has become a serious public health concern, as it is associated with outbreaks and severe diseases such as hemolytic-uremic syndrome. The molecular basis of its greater virulence than that of other serotypes is not completely known. OI-1 is a putative fimbria-encoding genomic island that is found almost exclusively in O157:H7 Shiga toxin-producing E. coli strains and may be associated with the enhanced pathogenesis of these strains. In this study, we identified and characterized a novel repressor of flagellar synthesis encoded by OI-1. We showed that deletion of Z0021 increased the motility of E. coli O157:H7, which correlated with an increase in flagellin production and enhanced assembly of flagella on the cell surface. In contrast, overexpression of Z0021 inhibited motility. We demonstrated that Z0021 exerted its regulatory effects downstream of the transcription and translation of flhDC but prior to the activation of class II/III promoters. Furthermore, the master regulator of flagellar synthesis, FlhD(4)C(2), was shown to be a high-copy suppressor of the nonmotile phenotype associated with elevated levels of Z0021--a finding consistent with Z0021-FlhD(4)C(2) being a potential regulatory complex. This work provides insight into the mechanism by which Z0021, which we have named fmrA, represses flagellar synthesis and is the first report of a fimbrial-operon-encoded inhibitor of motility in E. coli O157:H7.
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82
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Kudva IT, Griffin RW, Krastins B, Sarracino DA, Calderwood SB, John M. Proteins other than the locus of enterocyte effacement-encoded proteins contribute to Escherichia coli O157:H7 adherence to bovine rectoanal junction stratified squamous epithelial cells. BMC Microbiol 2012; 12:103. [PMID: 22691138 PMCID: PMC3420319 DOI: 10.1186/1471-2180-12-103] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 06/12/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In this study, we present evidence that proteins encoded by the Locus of Enterocyte Effacement (LEE), considered critical for Escherichia coli O157 (O157) adherence to follicle-associated epithelial (FAE) cells at the bovine recto-anal junction (RAJ), do not appear to contribute to O157 adherence to squamous epithelial (RSE) cells also constituting this primary site of O157 colonization in cattle. RESULTS Antisera targeting intimin-γ, the primary O157 adhesin, and other essential LEE proteins failed to block O157 adherence to RSE cells, when this pathogen was grown in DMEM, a culture medium that enhances expression of LEE proteins. In addition, RSE adherence of a DMEM-grown-O157 mutant lacking the intimin protein was comparable to that seen with its wild-type parent O157 strain grown in the same media. These adherence patterns were in complete contrast to that observed with HEp-2 cells (the adherence to which is mediated by intimin-γ), assayed under same conditions. This suggested that proteins other than intimin-γ that contribute to adherence to RSE cells are expressed by this pathogen during growth in DMEM. To identify such proteins, we defined the proteome of DMEM-grown-O157 (DMEM-proteome). GeLC-MS/MS revealed that the O157 DMEM-proteome comprised 684 proteins including several components of the cattle and human O157 immunome, orthologs of adhesins, hypothetical secreted and outer membrane proteins, in addition to the known virulence and LEE proteins. Bioinformatics-based analysis of the components of the O157 DMEM proteome revealed several new O157-specific proteins with adhesin potential. CONCLUSION Proteins other than LEE and intimin-γ proteins are involved in O157 adherence to RSE cells at the bovine RAJ. Such proteins, with adhesin potential, are expressed by this human pathogen during growth in DMEM. Ongoing experiments to evaluate their role in RSE adherence should provide both valuable insights into the O157-RSE interactions and new targets for more efficacious anti-adhesion O157 vaccines.
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Affiliation(s)
- Indira T Kudva
- Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa, 50010, USA
| | - Robert W Griffin
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
| | - Bryan Krastins
- Harvard Partners Center for Genetics and Genomics, 65 Landsdowne Street, Cambridge, Massachusetts, 02139, USA
- Present Address: Thermo-Fisher Scientific, Cambridge, Massachusetts, 02139, USA
| | - David A Sarracino
- Harvard Partners Center for Genetics and Genomics, 65 Landsdowne Street, Cambridge, Massachusetts, 02139, USA
- Present Address: Thermo-Fisher Scientific, Cambridge, Massachusetts, 02139, USA
| | - Stephen B Calderwood
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, 02114, USA
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts, 02114, USA
| | - Manohar John
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, 02114, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, 02114, USA
- Present Address: Pathovacs Inc., Ames, Iowa, 50010, USA
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83
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Lehti TA, Bauchart P, Dobrindt U, Korhonen TK, Westerlund-Wikström B. The fimbriae activator MatA switches off motility in Escherichia coli by repression of the flagellar master operon flhDC. MICROBIOLOGY-SGM 2012; 158:1444-1455. [PMID: 22422754 DOI: 10.1099/mic.0.056499-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Flagella provide advantages to Escherichia coli by facilitating taxis towards nutrients and away from unfavourable niches. On the other hand, flagellation is an energy sink to the bacterial cell, and flagella also stimulate host innate inflammatory responses against infecting bacteria. The flagellar assembly pathway is ordered and under a complex regulatory circuit that involves three classes of temporally regulated promoters as well as the flagellar master regulator FlhD(4)C(2). We report here that transcription of the flhDC operon from the class 1 promoter is under negative regulation by MatA, a key activator of the common mat (or ecp) fimbria operon that enhances biofilm formation by E. coli. Ectopic expression of MatA completely precluded motility and flagellar synthesis in the meningitis-associated E. coli isolate IHE 3034. Northern blotting, analysis of chromosomal promoter-lacZ fusions and electrophoretic mobility shift assays revealed an interaction between MatA and the flhDC promoter region that apparently repressed flagellum biosynthesis. However, inactivation of matA in the chromosome of IHE 3034 had only a minor effect on flagellation, which underlines the complexity of regulatory signals that promote flagellation in E. coli. We propose that the opposite regulatory actions of MatA on mat and on flhDC promoters advance the adaptation of E. coli from a planktonic to an adhesive lifestyle.
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Affiliation(s)
- Timo A Lehti
- Division of General Microbiology, Department of Biosciences, FI-00014 University of Helsinki, Finland
| | - Philippe Bauchart
- Institute for Molecular Biology of Infectious Diseases, Julius-Maximilians-University Würzburg, D-97080 Würzburg, Germany
| | - Ulrich Dobrindt
- Institute for Hygiene, University of Münster, D-48149 Münster, Germany.,Institute for Molecular Biology of Infectious Diseases, Julius-Maximilians-University Würzburg, D-97080 Würzburg, Germany
| | - Timo K Korhonen
- Division of General Microbiology, Department of Biosciences, FI-00014 University of Helsinki, Finland
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84
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Holmes A, Lindestam Arlehamn CS, Wang D, Mitchell TJ, Evans TJ, Roe AJ. Expression and regulation of the Escherichia coli O157:H7 effector proteins NleH1 and NleH2. PLoS One 2012; 7:e33408. [PMID: 22428045 PMCID: PMC3299786 DOI: 10.1371/journal.pone.0033408] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 02/13/2012] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND E. coli O157 carries two genes encoding the effector proteins NleH1 and NleH2 which are 87% identical. Despite the similarity between the proteins, the promoter regions upstream of the genes encoding the effectors are more divergent suggesting that the actual expression of the genes may be differentially regulated. This was tested by creating reporter fusions and examining their expression in different genetic backgrounds, media and on contact with host cells. The function of the proteins was also tested following transfection into host cells. PRINCIPAL FINDINGS Expression of both NleH1 and NleH2 was enhanced when cultured under conditions that stimulated expression of the Type Three Secretion System (T3SS) and was influenced by the regulators Ler and GrlA. Maximal expression of NleH1 required 531 bp of the upstream untranslated region but NleH2 required only 113 bp. Interestingly, contact with host cells strongly repressed expression of both NleH1 and NleH2. Following transfection, both proteins produced only minor effects on NF-κB activation when assessed using a NF-κB luciferase reporter assay, a result that is consistent with the recent report demonstrating the dependence on RPS3 for NleH1 modulation of NF-κB. SIGNIFICANCE This study demonstrates the importance of considering gene regulation when studying bacterial effector proteins. Despite their sequence similarity, NleH1 and NleH2 are expressed differentially and may, therefore, be translocated at distinct times during an infection.
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Affiliation(s)
| | | | | | | | | | - Andrew J. Roe
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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85
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Farfan MJ, Torres AG. Molecular mechanisms that mediate colonization of Shiga toxin-producing Escherichia coli strains. Infect Immun 2012; 80:903-13. [PMID: 22144484 PMCID: PMC3294676 DOI: 10.1128/iai.05907-11] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a group of pathogens which cause gastrointestinal disease in humans and have been associated with numerous food-borne outbreaks worldwide. The intimin adhesin has been considered for many years to be the only colonization factor in these strains. However, the rapid progress in whole-genome sequencing of different STEC serotypes has accelerated the discovery of other adhesins (fimbrial and afimbrial), which have emerged as important contributors to the intestinal colonization occurring during STEC infection. This review summarizes recent progress to identify and characterize, at the molecular level, novel adhesion and colonization factors in STEC strains, with an emphasis on their contribution to virulence traits, their host-pathogen interactions, the regulatory mechanisms controlling their expression, and their role as targets eliciting immune responses in the host.
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Affiliation(s)
- Mauricio J. Farfan
- Centro de Estudios Moleculares, Departamento de Pediatría, Hospital Dr. Luis Calvo Mackenna, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Alfredo G. Torres
- Department of Microbiology and Immunology, Department of Pathology, Sealy Center for Vaccine Development, and Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas, USA
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86
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Correlating levels of type III secretion and secreted proteins with fecal shedding of Escherichia coli O157:H7 in cattle. Infect Immun 2012; 80:1333-42. [PMID: 22252878 DOI: 10.1128/iai.05869-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The locus of enterocyte effacement (LEE) of Escherichia coli O157:H7 (O157) encodes a type III secretion system (T3SS) for secreting LEE-encoded and non-LEE-encoded virulence proteins that promote the adherence of O157 to intestinal epithelial cells and the persistence of this food-borne human pathogen in bovine intestines. In this study, we compared hha sepB and hha mutants of O157 for LEE transcription, T3SS activity, adherence to HEp-2 cells, persistence in bovine intestines, and the ability to induce changes in the expression of proinflammatory cytokines. LEE transcription was upregulated in the hha sepB and hha mutant strains compared to that in the wild-type strain, but the secretion of virulence proteins in the hha sepB mutant was severely compromised. This reduced secretion resulted in reduced adherence of the hha sepB mutant to Hep-2 cells, correlating with a significantly shorter duration and lower magnitude of fecal shedding in feces of weaned (n = 4 per group) calves inoculated with this mutant strain. The levels of LEE transcription, T3SS activity, and adherence to HEp-2 cells were much lower in the wild-type strain than in the hha mutant, but no significant differences were observed in the duration or the magnitude of fecal shedding in calves inoculated with these strains. Examination of the rectoanal junction (RAJ) tissues from three groups of calves showed no adherent O157 bacteria and similar proinflammatory cytokine gene expression, irrespective of the inoculated strain, with the exception that interleukin-1β was upregulated in calves inoculated with the hha sepB mutant. These results indicate that the T3SS is essential for intestinal colonization and prolonged shedding, but increased secretion of virulence proteins did not enhance the duration and magnitude of fecal shedding of O157 in cattle or have any significant impact on the cytokine gene expression in RAJ tissue compared with that in small intestinal tissue from the same calves.
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87
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Mayr UB, Kudela P, Atrasheuskaya A, Bukin E, Ignatyev G, Lubitz W. Rectal single dose immunization of mice with Escherichia coli O157:H7 bacterial ghosts induces efficient humoral and cellular immune responses and protects against the lethal heterologous challenge. Microb Biotechnol 2011; 5:283-94. [PMID: 22103353 PMCID: PMC3815788 DOI: 10.1111/j.1751-7915.2011.00316.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Bacterial ghosts (BGs) have been applied through oral, aerogenic, intraocular or intranasal routes for mucosal immunization using a wide range of experimental animals. All these applications required a booster after primary immunization to achieve protective immunity against the lethal challenge. Here we report for the first time that a single rectal dose of BGs produced from enterohaemorrhagic Escherichia coli (EHEC) O157:H7 fully protects mice against a 50% lethal challenge with a heterologous EHEC strain given at day 55. BGs from EHEC O157:H7 were prepared by a combination of protein E‐mediated cell lysis and expression of staphylococcal nuclease A guaranteeing the complete degradation of pathogen residual DNA. The lack of genetic material in the EHEC BGs vaccine abolished any potential hazard for horizontal gene transfer of plasmid encoded antibiotic resistance genes or pathogenic islands to the recipient's gut flora. Single rectal immunization using EHEC O157:H7 BGs without any addition of adjuvant significantly stimulated efficient humoral and cellular immune responses, and was equally protective as two immunizations, which indicates the possibility to develop a novel efficacious single dose mucosal EHEC O157:H7 BGs vaccine using a simplified immunization regimen.
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88
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Kudva I, Dean-Nystrom E. Bovine recto-anal junction squamous epithelial (RSE) cell adhesion assay for studying Escherichia coli O157 adherence. J Appl Microbiol 2011; 111:1283-94. [DOI: 10.1111/j.1365-2672.2011.05139.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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89
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Kitagawa R, Takaya A, Yamamoto T. Dual regulatory pathways of flagellar gene expression by ClpXP protease in enterohaemorrhagic Escherichia coli. MICROBIOLOGY-SGM 2011; 157:3094-3103. [PMID: 21903756 DOI: 10.1099/mic.0.051151-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In enterobacteria such as Escherichia coli and Salmonella species, flagellar biogenesis is strictly dependent upon the master regulator flhDC. Here, we demonstrate that in enterohaemorrhagic E. coli (EHEC), the flagellar regulon is controlled by ClpXP, a member of the ATP-dependent protease family, through two pathways: (i) post-translational control of the FlhD/FlhC master regulator and (ii) transcriptional control of the flhDC operon. Both FlhD and FlhC proteins accumulated markedly following ClpXP depletion, and their half-lives were significantly longer in the mutant cells, suggesting that ClpXP is responsible for degrading FlhD and FlhC proteins, leading to downregulation of flagellar expression. ClpXP was involved in regulating the transcription of the flhD promoter only when the cells had entered stationary phase in a culture medium that markedly induced expression of the locus of enterocyte effacement (LEE). Comparative analyses of transcription from the flhD promoter in EHEC cells with different genetic backgrounds suggested that the downregulation of flhDC expression by ClpXP is dependent on the LEE-encoded GrlR-GrlA system. We have also shown that the degradation of FlhD and FlhC by ClpXP is responsible for downregulating flagellar expression even when LEE expression is induced.
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Affiliation(s)
- Ryo Kitagawa
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Akiko Takaya
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
| | - Tomoko Yamamoto
- Department of Microbiology and Molecular Genetics, Graduate School of Pharmaceutical Sciences, Chiba University, Chiba 263-8522, Japan
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90
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Etienne-Mesmin L, Chassaing B, Sauvanet P, Denizot J, Blanquet-Diot S, Darfeuille-Michaud A, Pradel N, Livrelli V. Interactions with M cells and macrophages as key steps in the pathogenesis of enterohemorrhagic Escherichia coli infections. PLoS One 2011; 6:e23594. [PMID: 21858177 PMCID: PMC3157389 DOI: 10.1371/journal.pone.0023594] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 07/21/2011] [Indexed: 12/13/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are food-borne pathogens that can cause serious infections ranging from diarrhea to hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS). Translocation of Shiga-toxins (Stx) from the gut lumen to underlying tissues is a decisive step in the development of the infection, but the mechanisms involved remain unclear. Many bacterial pathogens target the follicle-associated epithelium, which overlies Peyer's patches (PPs), cross the intestinal barrier through M cells and are captured by mucosal macrophages. Here, translocation across M cells, as well as survival and proliferation of EHEC strains within THP-1 macrophages were investigated using EHEC O157:H7 reference strains, isogenic mutants, and 15 EHEC strains isolated from HC/HUS patients. We showed for the first time that E. coli O157:H7 strains are able to interact in vivo with murine PPs, to translocate ex vivo through murine ileal mucosa with PPs and across an in vitro human M cell model. EHEC strains are also able to survive and to produce Stx in macrophages, which induce cell apoptosis and Stx release. In conclusion, our results suggest that the uptake of EHEC by M cells and underlying macrophages in the PP may be a critical step in Stx translocation and release in vivo. A new model for EHEC infection in humans is proposed that could help in a fuller understanding of EHEC-associated diseases.
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Affiliation(s)
- Lucie Etienne-Mesmin
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, ERT 18, Conception, Ingénierie et Développement de l'Aliment et du Médicament, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France
| | - Benoit Chassaing
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Pierre Sauvanet
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
- CHU Clermont Ferrand, Pôle des Pathologies Digestives, Clermont-Ferrand, France
| | - Jérémy Denizot
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Stéphanie Blanquet-Diot
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, ERT 18, Conception, Ingénierie et Développement de l'Aliment et du Médicament, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France
| | - Arlette Darfeuille-Michaud
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Nathalie Pradel
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
| | - Valérie Livrelli
- Clermont Université, Université d'Auvergne, Centre de Recherche en Nutrition Humaine Auvergne, JE 2526 Evolution des bactéries pathogènes et susceptibilité génétique de l'hôte, Clermont-Ferrand, France
- INRA, Institut National Recherche Agronomique, Unité Sous Contrat USC-2018, Clermont-Ferrand, France
- Clermont Université, Université d'Auvergne, UFR Pharmacie, Clermont-Ferrand, France
- CHU Clermont-Ferrand, Service Bactériologie Mycologie Parasitologie, Clermont-Ferrand, France
- * E-mail:
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91
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Tildesley MJ, Gally DL, McNeilly TN, Low JC, Mahajan A, Savill NJ. Insights into mucosal innate responses to Escherichia coli O157 : H7 colonization of cattle by mathematical modelling of excretion dynamics. J R Soc Interface 2011; 9:518-27. [PMID: 21849385 DOI: 10.1098/rsif.2011.0293] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mathematical model-based statistical inference applied to within-host dynamics of infectious diseases can help dissect complex interactions between hosts and microbes. This work has applied advances in model-based inference to understand colonization of cattle by enterohaemorrhagic Escherichia coli O157 : H7 at the terminal rectum. A mathematical model was developed based on niche replication and transition rates at this site. A nested-model comparison, applied to excretion curves from 25 calves, was used to reduce complexity while maintaining integrity. We conclude that, 5-9 days post inoculation, the innate immune response negates bacterial replication on the epithelium and either reduces attachment to or increases detachment from the epithelium of the terminal rectum. Thus, we provide a broadly applicable model that gives novel insights into bacterial replication rates in vivo and the timing and impact of host responses.
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Affiliation(s)
- Michael J Tildesley
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JT, UK.
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92
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Long polar fimbriae of enterohemorrhagic Escherichia coli O157:H7 bind to extracellular matrix proteins. Infect Immun 2011; 79:3744-50. [PMID: 21708988 DOI: 10.1128/iai.05317-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Adherence to intestinal cells is a key process in infection caused by enterohemorrhagic Escherichia coli (EHEC). Several adhesion factors that mediate the binding of EHEC to intestinal cells have been described, but the receptors involved in their recognition are not fully characterized. Extracellular matrix (ECM) proteins might act as receptors involved in the recognition of enteric pathogens, including EHEC. In this study, we sought to characterize the binding of EHEC O157:H7 to ECM proteins commonly present in the intestine. We found that EHEC prototype strains as well as other clinical isolates adhered more abundantly to surfaces coated with fibronectin, laminin, and collagen IV. Further characterization of this phenotype, by using antiserum raised against the LpfA1 putative major fimbrial subunit and by addition of mannose, showed that a reduced binding of EHEC to ECM proteins was observed in a long polar fimbria (lpf) mutant. We also found that the two regulators, H-NS and Ler, had an effect in EHEC Lpf-mediated binding to ECM, supporting the roles of these tightly regulated fimbriae as adherence factors. Purified Lpf major subunit bound to all of the ECM proteins tested. Finally, increased bacterial adherence was observed when T84 cells, preincubated with ECM proteins, were infected with EHEC. Taken together, these findings suggest that the interaction of Lpf and ECM proteins contributes to the EHEC colonization of the gastrointestinal tract.
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93
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Hiriart Y, Errea A, González Maciel D, Lopez JC, Rumbo M. A method for the purification of bacterial flagellin that allows simple upscaling. World J Microbiol Biotechnol 2011; 28:15-21. [DOI: 10.1007/s11274-011-0786-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 05/09/2011] [Indexed: 10/25/2022]
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94
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Fraser-Pitt DJ, Cameron P, McNeilly TN, Boyd A, Manson EDT, Smith DGE. Phosphorylation of the epidermal growth factor receptor (EGFR) is essential for interleukin-8 release from intestinal epithelial cells in response to challenge with Escherichia coli O157 : H7 flagellin. MICROBIOLOGY-SGM 2011; 157:2339-2347. [PMID: 21546588 DOI: 10.1099/mic.0.047670-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Enterohaemorrhagic Escherichia coli O157 : H7 is a major foodborne and environmental pathogen responsible for both sporadic cases and outbreaks of food poisoning, which can lead to serious sequelae, such as haemolytic uraemic syndrome. The structural subunit of E. coli O157 : H7 flagella is flagellin, which is both the antigenic determinant of the H7 serotype, an important factor in colonization, and an immunomodulatory protein that has been determined to be a major pro-inflammatory component through the instigation of host cell signalling pathways. Flagellin has highly conserved N- and C-terminal regions that are recognized by the host cell pattern recognition receptor Toll-like receptor (TLR) 5. Activation of this receptor triggers cell signalling cascades, which are known to activate host cell kinases and transcription factors that respond with the production of inflammatory mediators such as the chemokine interleukin-8 (IL-8), although the exact components of this pathway are not yet fully characterized. We demonstrate that E. coli O157 : H7-derived flagellin induces rapid phosphorylation of the epidermal growth factor receptor (EGFR), as an early event in intestinal epithelial cell signalling, and that this is required for the release of the pro-inflammatory cytokine IL-8.
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Affiliation(s)
- Douglas J Fraser-Pitt
- Biomedical Sciences and Microbiology Group, School of Life, Sport and Social Sciences, Faculty of Health, Life and Social Sciences, Sighthill Campus, Edinburgh Napier University, Edinburgh EH11 4BN, UK
| | - Pamela Cameron
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Amanda Boyd
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - Erin D T Manson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
| | - David G E Smith
- Institute for Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Glasgow G61 1QH, UK.,Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian EH26 0PZ, UK
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95
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Reduction of Escherichia coli O157:H7 shedding in cattle by addition of chitosan microparticles to feed. Appl Environ Microbiol 2011; 77:2611-6. [PMID: 21335379 DOI: 10.1128/aem.02587-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterohemorrhagic Escherichia coli O157:H7 (EHEC) is a significant human pathogen that resides in healthy cattle. It is thought that a reduction in the prevalence and numbers of EHEC in cattle will reduce the load of EHEC entering the food chain. To this end, an intervention strategy involving the addition of chitosan microparticles (CM) to feed in order to reduce the carriage of this pathogen in cattle was evaluated. Experiments with individual Holstein calves and a crossover study found that the addition of CM to feed decreased E. coli O157:H7 shedding. In the crossover study, CM resulted in statistically significant reductions in the numbers recovered from rectal swab samples (P < 0.05) and the duration of shedding (P < 0.05). The effects of feeding CM to calves differed, indicating that the optimal levels of CM may differ between animals or that other factors are involved in the interaction between CM and E. coli O157:H7. In vitro studies demonstrated that E. coli O157:H7 binds to CM, suggesting that the reduction in shedding may result at least in part from the binding of positively charged CM to negatively charged E. coli cells. Additional studies are needed to determine the impact of CM feeding on animal production, but the results from this study indicate that supplementing feed with CM reduces the shedding of E. coli O157:H7 in cattle.
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96
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Abstract
Previously, our laboratories reported that zinc inhibited expression of several important virulence factors in enteropathogenic Escherichia coli (EPEC) and reduced EPEC-induced intestinal damage in vivo. Since EPEC is genetically related to Shiga-toxigenic E. coli (STEC), we wondered whether the beneficial effects of zinc extended to STEC as well. Treatment options for STEC infection are very limited, since antibiotics tend to exacerbate disease via enhanced toxin production, so a safe intervention for this infection would be welcome. In this study, we report that in STEC strains zinc inhibits adherence to cultured cells as well as expression of EHEC secreted protein A (EspA). In addition, zinc inhibits the expression of Shiga toxin (Stx) at both the protein and the RNA level. Zinc inhibits basal and antibiotic-induced Stx production and inhibits both Stx1 and Stx2 by ≥90% at a concentration of 0.4 mM zinc. Rabbit EPEC strains were selected for acquisition of Stx-encoding bacteriophages, and these rabbit STEC strains (designated RDEC-H19A and E22-stx2) were used to test the effects of zinc in vivo in ligated rabbit intestinal loops. In vivo, zinc reduced fluid secretion into loops, inhibited mucosal adherence, reduced the amount of toxin in the loops, and reduced STEC-induced histological damage (villus blunting). Zinc has beneficial inhibitory effects against STEC strains that parallel those observed in EPEC. In addition, zinc strongly inhibits Stx expression; since Stx is responsible for the extraintestinal effects of STEC infection, such as hemolytic-uremic syndrome (HUS), zinc might be capable of preventing severe sequelae of STEC infection.
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97
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Activation of motility by sensing short-chain fatty acids via two steps in a flagellar gene regulatory cascade in enterohemorrhagic Escherichia coli. Infect Immun 2010; 79:1016-24. [PMID: 21149585 DOI: 10.1128/iai.00927-10] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The regulated expression of virulence genes is critical for successful infection by an intestinal pathogen. Bacteria rely on sensing environmental signals to find preferable niches and reach the infectious state. Orally ingested enterohemorrhagic Escherichia coli (EHEC) travels through the gastrointestinal tract and encounters a variety of environmental factors, some of which act as triggering signals for the induction of virulence genes. Butyrate, one of the main short-chain fatty acids (SCFAs), is such a signal, enhancing the expression of genes for intimate attachment and type III secretion. We further explored the role of SCFAs and found a positive effect of SCFAs on flagellar expression. Although EHEC did not produce flagella when grown in Dulbecco's modified Eagle's medium (DMEM), a tissue culture medium that enhances virulence gene expression, the addition of SCFAs to the medium induced the production of flagella, and the EHEC bacteria became motile. Among SCFAs, butyrate simultaneously activates both virulence and flagellar genes. Flagella did not affect initial adherence, and they were not expressed in adherent bacteria during microcolony formation. SCFAs activated flagellar genes via two regulatory steps. Butyrate activated the flhDC regulatory genes through leucine-responsive regulatory protein (Lrp), which is also a regulator of virulence genes. However, butyrate, acetate, and propionate also activated downstream genes independently of flhDC activation. Consequently, when encountering increased concentrations of SCFAs, which are abundant in acetate, in the intestine, EHEC first activates flagellar production and motility, followed by genes involved in adherence and type III secretion, which leads to efficient adherence in a preferable niche.
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98
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Effect of a new probiotic Saccharomyces cerevisiae strain on survival of Escherichia coli O157:H7 in a dynamic gastrointestinal model. Appl Environ Microbiol 2010; 77:1127-31. [PMID: 21131521 DOI: 10.1128/aem.02130-10] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Survival of Escherichia coli O157:H7 was investigated using a dynamic gastrointestinal model. A high bacterial mortality was observed in the stomach and duodenum. In contrast, bacteria grew in the distal parts of the small intestine. The coadministration of Saccharomyces cerevisiae CNCM I-3856 led to a significant reduction of bacterial resumption, maybe through ethanol production.
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99
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Schüller S, Phillips AD. Microaerobic conditions enhance type III secretion and adherence of enterohaemorrhagic Escherichia coli to polarized human intestinal epithelial cells. Environ Microbiol 2010; 12:2426-35. [PMID: 20406285 PMCID: PMC4966633 DOI: 10.1111/j.1462-2920.2010.02216.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Advances in the understanding of the pathogenesis of enterohaemorrhagic Escherichia coli (EHEC) have greatly benefited from the use of human epithelial cell lines under aerobic conditions. However, in the target site of EHEC infection, the human intestine, conditions are microaerobic. In our study we used polarized human colon carcinoma cells in a vertical diffusion chamber system to investigate the influence of reduced apical oxygen levels on EHEC colonization. While apical microaerobiosis did not affect cell integrity and barrier function, numbers of adherent bacteria were significantly increased under low compared with high apical oxygen concentrations. In addition, expression and translocation of EHEC type III secreted (T3S) effector proteins was considerably enhanced under microaerobic conditions and dependent on the presence of host cells. Increased colonization was mainly mediated via EspA as adherence levels of an isogenic deletion mutant were not influenced by low oxygen levels. Other potential adherence factors (E. coli common pilus and flagella) were only minimally expressed under high and low oxygen levels. Addition of nitrate and trimethylamine N-oxide as terminal electron acceptors for anaerobic respiration failed to further increase bacterial colonization or T3S under microaerobiosis. This study indicates that EHEC T3S and colonization are enhanced by the microaerobic environment in the gut and therefore might be underestimated in conventional aerobic cell culture systems.
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Affiliation(s)
- Stephanie Schüller
- Centre for Paediatric Gastroenterology, UCL Medical School, Royal Free Campus, London, UK.
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100
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Moxley RA, Smith DR. Attaching-effacing Escherichia coli infections in cattle. Vet Clin North Am Food Anim Pract 2010; 26:29-56, table of contents. [PMID: 20117541 PMCID: PMC7127223 DOI: 10.1016/j.cvfa.2009.10.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Diarrheagenic Escherichia coli are now broadly placed into 6 classes based on virulence mechanisms. One of these classes, enterotoxigenic E coli, is the most common cause of diarrhea in beef and dairy calves in the first 4 days of life. Two other diarrheagenic classes, enterohemorrhagic E coli (EHEC) and enteropathogenic E coli (EPEC), are important causes of disease in human beings, but less well substantiated causes of diarrhea in calves. E coli strains that cause hemorrhagic colitis and hemolytic uremic syndrome in humans, express high levels of Shiga toxin, cause attaching-effacing (A/E) lesions in intestinal epithelial cells, and possess a specific 60-MDa EHEC plasmid are known as EHEC. One feature EHEC and EPEC have in common is the causation of intestinal epithelial lesions known as attaching and effacing (A/E). Attaching-effacing E coli (AEEC) is a designation for those E coli strains known to cause A/E lesions or at least carry the genes for this trait, and therefore include organisms that fall into either the EHEC or EPEC classes. Because cattle are carriers of many different serotypes of EHEC, much emphasis has been placed on the public health and food safety concerns associated with the fecal shedding of these organisms. However, much less emphasis has been given to their roles as diarrheagenic pathogens of cattle. The goal of this article is to address the question of pathogenicity, with a review that focuses on the results of studies of natural and experimental infections with these organisms. The authors conclude that there is overwhelming evidence that many different serogroups of AEEC are diarrheagenic pathogens of calves.
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Affiliation(s)
- Rodney A Moxley
- School of Veterinary Medicine & Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583-0905, USA.
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