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Cryoelectron-microscopy structure of the enteropathogenic Escherichia coli type III secretion system EspA filament. Proc Natl Acad Sci U S A 2021; 118:2022826118. [PMID: 33397726 PMCID: PMC7812819 DOI: 10.1073/pnas.2022826118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic Escherichia coli (EHEC) utilize a macromolecular type III secretion system (T3SS) to inject effector proteins into eukaryotic cells. This apparatus spans the inner and outer bacterial membranes and includes a helical needle protruding into the extracellular space. Thus far observed only in EPEC and EHEC and not found in other pathogenic Gram-negative bacteria that have a T3SS is an additional helical filament made by the EspA protein that forms a long extension to the needle, mediating both attachment to eukaryotic cells and transport of effector proteins through the intestinal mucus layer. Here, we present the structure of the EspA filament from EPEC at 3.4 Å resolution. The structure reveals that the EspA filament is a right-handed 1-start helical assembly with a conserved lumen architecture with respect to the needle to ensure the seamless transport of unfolded cargos en route to the target cell. This functional conservation is despite the fact that there is little apparent overall conservation at the level of sequence or structure with the needle. We also unveil the molecular details of the immunodominant EspA epitope that can now be exploited for the rational design of epitope display systems.
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Nadler H, Shaulov L, Blitsman Y, Mordechai M, Jopp J, Sal-Man N, Berkovich R. Deciphering the Mechanical Properties of Type III Secretion System EspA Protein by Single Molecule Force Spectroscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6261-6270. [PMID: 29726683 DOI: 10.1021/acs.langmuir.8b01198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Bacterial pathogens inject virulence factors into host cells during bacterial infections using type III secretion systems. In enteropathogenic Escherichia coli, this system contains an external filament, formed by a self-oligomerizing protein called E. coli secreted protein A (EspA). The EspA filament penetrates the thick viscous mucus layer to facilitate the attachment of the bacteria to the gut-epithelium. To do that, the EspA filament requires noteworthy mechanical endurance considering the mechanical shear stresses found within the intestinal tract. To date, the mechanical properties of the EspA filament and the structural and biophysical knowledge of monomeric EspA are very limited, mostly due to the strong tendency of the protein to self-oligomerize. To overcome this limitation, we employed a single molecule force spectroscopy (SMFS) technique and studied the mechanical properties of EspA. Force extension dynamic of (I91)4-EspA-(I91)4 chimera revealed two structural unfolding events occurring at low forces during EspA unfolding, thus indicating no unique mechanical stability of the monomeric protein. SMFS examination of purified monomeric EspA protein, treated by a gradually refolding protocol, exhibited similar mechanical properties as the EspA protein within the (I91)4-EspA-(I91)4 chimera. Overall, our results suggest that the mechanical integrity of the EspA filament likely originates from the interactions between EspA monomers and not from the strength of an individual monomer.
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Affiliation(s)
- Hila Nadler
- Department of Chemical Engineering , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
| | - Lihi Shaulov
- Department of Microbiology, Immunology and Genetics , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
| | - Yossi Blitsman
- Department of Chemical Engineering , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
| | - Moran Mordechai
- Department of Chemical Engineering , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
| | - Jürgen Jopp
- The Ilse Katz Institute for Nanoscale Science and Technology , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
| | - Neta Sal-Man
- Department of Microbiology, Immunology and Genetics , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
| | - Ronen Berkovich
- Department of Chemical Engineering , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
- The Ilse Katz Institute for Nanoscale Science and Technology , Ben-Gurion University of the Negev , Beer Sheva 8410501 , Israel
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O'Ryan M, Vidal R, del Canto F, Carlos Salazar J, Montero D. Vaccines for viral and bacterial pathogens causing acute gastroenteritis: Part II: Vaccines for Shigella, Salmonella, enterotoxigenic E. coli (ETEC) enterohemorragic E. coli (EHEC) and Campylobacter jejuni. Hum Vaccin Immunother 2015; 11:601-19. [PMID: 25715096 DOI: 10.1080/21645515.2015.1011578] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In Part II we discuss the following bacterial pathogens: Shigella, Salmonella (non-typhoidal), diarrheogenic E. coli (enterotoxigenic and enterohemorragic) and Campylobacter jejuni. In contrast to the enteric viruses and Vibrio cholerae discussed in Part I of this series, for the bacterial pathogens described here there is only one licensed vaccine, developed primarily for Vibrio cholerae and which provides moderate protection against enterotoxigenic E. coli (ETEC) (Dukoral(®)), as well as a few additional candidates in advanced stages of development for ETEC and one candidate for Shigella spp. Numerous vaccine candidates in earlier stages of development are discussed.
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Key Words
- CFU, colony-forming units
- CFs, colonization factors
- CT, cholera toxin
- CT-B cholera toxin B subunit
- Campylobacter
- CtdB, cytolethal distending toxin subunit B
- E. coli
- EHEC
- EPEC, enteropathogenic E. coli
- ETEC
- ETEC, enterotoxigenic E. coli
- GEMS, Global enterics multicenter study
- HUS, hemolytic uremic syndrome
- IM, intramuscular
- IgA, immunoglobulin A
- IgG, immunoglobulin G
- IgM, immunoglobulin M
- LEE, locus of enterocyte effacement
- LPS, lipopolysaccharide
- LT, heat labile toxin
- LT-B
- OMV, outer membrane vesicles
- ST, heat stable toxin
- STEC
- STEC, shigatoxin producing E. coli
- STh, human heat stable toxin
- STp, porcine heat stable toxin
- Salmonella
- Shigella
- Stx, shigatoxin
- TTSS, type III secretion system
- V. cholera
- WHO, World Health Organization
- acute diarrhea
- dmLT, double mutant heat labile toxin
- enteric pathogens
- enterohemorrhagic E. coli
- gastroenteritis
- heat labile toxin B subunit
- norovirus
- rEPA, recombinant exoprotein A of Pseudomonas aeruginosa
- rotavirus
- vaccines
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Affiliation(s)
- Miguel O'Ryan
- a Microbiology and Mycology Program; Institute of Biomedical Sciences; Faculty of Medicine; Universidad de Chile; Santiago, Chile
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Praekelt U, Reissbrodt R, Kresse A, Pavankumar A, Sankaran K, James R, Jesudason M, Anandan S, Prakasam A, Balaji V, Dutta S, Dutta S, Ramamurthy T, Fischer R, Sander P, Schaumann R, Navarro A, Williams P. Monoclonal antibodies against all known variants of EspA: development of a simple diagnostic test for enteropathogenic Escherichia coli based on a key virulence factor. J Med Microbiol 2014; 63:1595-1607. [PMID: 25231626 PMCID: PMC4250835 DOI: 10.1099/jmm.0.076323-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 09/16/2014] [Indexed: 11/23/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) are a major cause of infant diarrhoea in developing countries and a significant public health issue in industrialized countries. Currently there are no simple tests available for the diagnosis of EPEC. Serology of O-antigens is widely used routinely in many laboratories throughout the world, even though it has been known for many years to be an unreliable indicator of EPEC virulence. We have developed a simple, low-cost immunodiagnostic test based on the EspA filament, an essential virulence factor of EPEC and the related enterohaemorrhagic E. coli (EHEC). Using recombinant proteins of the five major variants of EspA as immunogens, we raised a panel of three monoclonal antibodies in mice that detects all variants of the native target in bacterial cultures. The antibodies proved suitable for application in sandwich-type assays, including ELISA and lateral flow immunoassays (LFI). Prototypes for both assays were specific for EPEC and EHEC strains when tested against a panel of control micro-organisms. We have also developed a simple, affordable culture medium, A/E medium, which optimizes expression of EspA allowing improved sensitivity of detection compared with standard Dulbecco's modified Eagle's medium. Together these reagents form the basis of robust, informative tests for EPEC for use especially in developing countries but also for routine screening in any clinical laboratory.
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Affiliation(s)
- Uta Praekelt
- Department of Genetics, University of Leicester, Leicester, UK
| | - Rolf Reissbrodt
- Abteilung für Infektionskrankheiten, Robert Koch Institut, Wernigerode, Germany
| | - Andreas Kresse
- Abteilung für Infektionskrankheiten, Robert Koch Institut, Wernigerode, Germany
| | | | | | - Roger James
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK
| | | | | | | | | | - Shanta Dutta
- National Institute of Cholera and Enteric Diseases, Kolkata, India
| | - Sanjucta Dutta
- National Institute of Cholera and Enteric Diseases, Kolkata, India
| | | | | | | | - Reiner Schaumann
- Institut für Medizinische Mikrobiologie, Universität Leipzig, Leipzig, Germany
| | - Armando Navarro
- Department of Public Health, Faculty of Medicine, National Autonomous University of Mexico, Mexico City, Mexico
| | - Peter Williams
- Department of Genetics, University of Leicester, Leicester, UK
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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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Jennings ME, Quick LN, Ubol N, Shrom S, Dollahon N, Wilson JW. Characterization of Salmonella type III secretion hyper-activity which results in biofilm-like cell aggregation. PLoS One 2012; 7:e33080. [PMID: 22412985 PMCID: PMC3297627 DOI: 10.1371/journal.pone.0033080] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 02/07/2012] [Indexed: 01/06/2023] Open
Abstract
We have previously reported the cloning of the Salmonella enterica serovar Typhimurium SPI-1 secretion system and the use of this clone to functionally complement a ΔSPI-1 strain for type III secretion activity. In the current study, we discovered that S. Typhimurium cultures containing cloned SPI-1 display an adherent biofilm and cell clumps in the media. This phenotype was associated with hyper-expression of SPI-1 type III secretion functions. The biofilm and cell clumps were associated with copious amounts of secreted SPI-1 protein substrates SipA, SipB, SipC, SopB, SopE, and SptP. We used a C-terminally FLAG-tagged SipA protein to further demonstrate SPI-1 substrate association with the cell aggregates using fluorescence microscopy and immunogold electron microscopy. Different S. Typhimurium backgrounds and both flagellated and nonflagellated strains displayed the biofilm phenotype. Mutations in genes essential for known bacterial biofilm pathways (bcsA, csgBA, bapA) did not affect the biofilms formed here indicating that this phenomenon is independent of established biofilm mechanisms. The SPI-1-mediated biofilm was able to massively recruit heterologous non-biofilm forming bacteria into the adherent cell community. The results indicate a bacterial aggregation phenotype mediated by elevated SPI-1 type III secretion activity with applications for engineered biofilm formation, protein purification strategies, and antigen display.
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Affiliation(s)
- Matthew E. Jennings
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, United States of America
| | - Laura N. Quick
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Nicha Ubol
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - Sally Shrom
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - Norman Dollahon
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
| | - James W. Wilson
- Department of Biology, Villanova University, Villanova, Pennsylvania, United States of America
- * E-mail:
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Praekelt U, Kopp PM, Rehm K, Linder S, Bate N, Patel B, Debrand E, Manso AM, Ross RS, Conti F, Zhang MZ, Harris RC, Zent R, Critchley DR, Monkley SJ. New isoform-specific monoclonal antibodies reveal different sub-cellular localisations for talin1 and talin2. Eur J Cell Biol 2012; 91:180-91. [PMID: 22306379 PMCID: PMC3629562 DOI: 10.1016/j.ejcb.2011.12.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 12/13/2011] [Accepted: 12/19/2011] [Indexed: 11/24/2022] Open
Abstract
Talins are adaptor proteins that connect the integrin family of cell adhesion receptors to cytoskeletal actin. Vertebrates express two closely related talins encoded by separate genes, and while it is well established that talin1 plays a key role in cell adhesion and spreading, little is known about the role of talin2. To facilitate such studies, we report the characterisation of 4 new isoform-specific talin mouse monoclonal antibodies that work in Western blotting, immuno-precipitation, immuno-fluorescence and immuno-histochemistry. Using these antibodies, we show that talin1 and talin2 do not form heterodimers, and that they are differentially localised within the cell. Talin1 was concentrated in peripheral focal adhesions while talin2 was observed in both focal and fibrillar adhesions, and knock-down of talin2 compromised fibronectin fibrillogenesis. Although differentiated human macrophages express both isoforms, only talin1 showed discrete staining and was localised to the ring structure of podosomes. However, siRNA-mediated knock-down of macrophage talin2 led to a significant reduction in podosomal matrix degradation. We have also used the antibodies to localise each isoform in tissue sections using both cryostat and paraffin-embedded material. In skeletal muscle talin2 was localised to both myotendinous junctions and costameres while talin1 was restricted to the former structure. In contrast, both isoforms co-localised in kidney with staining of the glomerulus, and the tubular epithelial and interstitial cells of the cortex and medulla. We anticipate that these antibodies will form a valuable resource for future studies on the function of the two major talin isoforms.
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Affiliation(s)
- Uta Praekelt
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Petra M. Kopp
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Kerstin Rehm
- University Medical Center Eppendorf, 20246 Hamburg, Germany
| | - Stefan Linder
- University Medical Center Eppendorf, 20246 Hamburg, Germany
| | - Neil Bate
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Bipin Patel
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Emmanuel Debrand
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Ana Maria Manso
- Department of Medicine, University of California at San Diego, School of Medicine, La Jolla, CA, USA
- VA Healthcare San Diego, CA 92161, USA
| | - Robert S. Ross
- Department of Medicine, University of California at San Diego, School of Medicine, La Jolla, CA, USA
- VA Healthcare San Diego, CA 92161, USA
| | - Franceso Conti
- Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London WC1N 1EH, UK
| | - Ming-Zhi Zhang
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, North Nashville, TN 37232, USA
| | - Raymond C. Harris
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, North Nashville, TN 37232, USA
- Department of Medicine, Veterans Affairs Hospital, Nashville, TN 37212, USA
| | - Roy Zent
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, North Nashville, TN 37232, USA
- Department of Medicine, Veterans Affairs Hospital, Nashville, TN 37212, USA
| | - David R. Critchley
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
| | - Susan J. Monkley
- Department of Biochemistry, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK
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Moura RA, Sircili MP, Leomil L, Matté MH, Trabulsi LR, Elias WP, Irino K, Pestana de Castro AF. Clonal relationship among atypical enteropathogenic Escherichia coli strains isolated from different animal species and humans. Appl Environ Microbiol 2009; 75:7399-408. [PMID: 19801470 PMCID: PMC2786407 DOI: 10.1128/aem.00636-09] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Forty-nine typical and atypical enteropathogenic Escherichia coli (EPEC) strains belonging to different serotypes and isolated from humans, pets (cats and dogs), farm animals (bovines, sheep, and rabbits), and wild animals (monkeys) were investigated for virulence markers and clonal similarity by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The virulence markers analyzed revealed that atypical EPEC strains isolated from animals have the potential to cause diarrhea in humans. A close clonal relationship between human and animal isolates was found by MLST and PFGE. These results indicate that these animals act as atypical EPEC reservoirs and may represent sources of infection for humans. Since humans also act as a reservoir of atypical EPEC strains, the cycle of mutual infection of atypical EPEC between animals and humans, mainly pets and their owners, cannot be ruled out since the transmission dynamics between the reservoirs are not yet clearly understood.
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Affiliation(s)
- Rodrigo A. Moura
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Marcelo P. Sircili
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Luciana Leomil
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Maria Helena Matté
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Luiz R. Trabulsi
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Waldir P. Elias
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Kinue Irino
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
| | - Antonio F. Pestana de Castro
- Laboratory of Human and Veterinary Bacteriology, Biomedical Sciences Institute, University of São Paulo, São Paulo, SP, Brazil, Laboratory of Bacteriology, Butantan Institute, São Paulo, SP, Brazil, Laboratory of Public Health, Public Health School, University of São Paulo, São Paulo, SP, Brazil, Adolfo Lutz Institute, São Paulo, SP, Brazil
- Corresponding author. Mailing address: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Avenida Prof. Lineu Prestes 1374, 05508-900 São Paulo, SP, Brazil. Phone: 5511 3091-7298. Fax: 5511 3091-7354. E-mail:
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McNeilly TN, Mitchell MC, Rosser T, McAteer S, Low JC, Smith DGE, Huntley JF, Mahajan A, Gally DL. Immunization of cattle with a combination of purified intimin-531, EspA and Tir significantly reduces shedding of Escherichia coli O157:H7 following oral challenge. Vaccine 2009; 28:1422-8. [PMID: 19903545 DOI: 10.1016/j.vaccine.2009.10.076] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 09/28/2009] [Accepted: 10/14/2009] [Indexed: 01/06/2023]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a human pathogen that can cause gastrointestinal disease with potentially fatal consequences as a result of systemic Shiga toxin activity. Cattle are the main reservoir host of EHEC O157 and interventions need to be developed that prevent cattle colonization or limit shedding of the organism from this host. EHEC O157 predominately colonizes the bovine terminal rectum and requires a type III secretion system (T3SS) for adherence and persistence at this site. A vaccine based on concentrated bacterial supernatant that contains T3S proteins has shown some efficacy. Here we have demonstrated that vaccination with a combination of antigens associated with T3S-mediated adherence; the translocon filament protein, EspA, the extracellular region of the outer membrane adhesin, intimin, and the translocated intimin receptor (Tir) significantly reduced shedding of EHEC O157 from experimentally infected animals. Furthermore, this protection may be augmented by addition of H7 flagellin to the vaccine preparation that has been previously demonstrated to be partially protective in cattle. Protection correlates with systemic and mucosal antibody responses to the defined antigens and validates the targeting of these colonization factors.
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Affiliation(s)
- Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 0PZ, UK
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Bovine colostrum contains immunoglobulin G antibodies against intimin, EspA, and EspB and inhibits hemolytic activity mediated by the type three secretion system of attaching and effacing Escherichia coli. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2008; 15:1208-13. [PMID: 18562563 DOI: 10.1128/cvi.00027-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is the main cause of hemolytic-uremic syndrome, an endemic disease in Argentina which had an incidence in 2005 of 13.9 cases per 100,000 children younger than 5 years old. Cattle appear to be a major reservoir of EHEC, and a serological response to EHEC antigens has been demonstrated in natural and experimental infections. In the current study, antibodies against proteins implicated in EHEC's ability to form attaching and effacing lesions, some of which are exported to the host cell via a type three secretion system (TTSS), were identified in bovine colostrum by Western blot analysis. Twenty-seven (77.0%) of the 35 samples examined contained immunoglobulin G (IgG) antibodies against the three proteins assayed in this study: EspA, EspB, and the carboxy-terminal 280 amino acids of gamma-intimin, an intimin subtype associated mainly with O157:H7 and O145:H- serotypes. Every colostrum sample was able to inhibit, in a range between 45.9 and 96.7%, the TTSS-mediated hemolytic activity of attaching and effacing E. coli. The inhibitory effect was partially mediated by IgG and lactoferrin. In conclusion, we found that early colostrum from cows contains antibodies, lactoferrin, and other unidentified substances that impair TTSS function in attaching and effacing E. coli strains. Bovine colostrum might act by reducing EHEC colonization in newborn calves and could be used as a prophylactic measure to protect non-breast-fed children against EHEC infection in an area of endemicity.
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Structural and functional properties of chimeric EspA-FliCi filaments of EPEC. J Mol Biol 2008; 378:243-50. [PMID: 18353364 DOI: 10.1016/j.jmb.2008.02.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 02/18/2008] [Accepted: 02/20/2008] [Indexed: 12/26/2022]
Abstract
Enteropathogenic Escherichia coli utilise a filamentous type III secretion system to translocate effector proteins into host gut epithelial cells. The primary constituent of the extracellular component of the filamentous type III secretion system is EspA. This forms a long flexible helical conduit between the bacterium and host and has a structure almost identical to that of the flagella filament. We have inserted the D3 domain of FliCi (from Salmonella typhimurium) into the outer domain of EspA and have studied the structure and function of modified filaments when expressed in an enteropathogenic E. coli espA mutant. We found that the chimeric protein EspA-FliCi filaments were biologically active as they supported protein secretion and translocation [assessed by their ability to trigger actin polymerisation beneath adherent bacteria (fluorescent actin staining test)]. The expressed filaments were recognised by both EspA and FliCi antisera. Visualisation and analysis of the chimeric filaments by electron microscopy after negative staining showed that, remarkably, EspA filaments are able to tolerate a large protein insertion without a significant effect on their helical architecture.
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12
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Identification of amino acid residues within the N-terminal domain of EspA that play a role in EspA filament biogenesis and function. J Bacteriol 2008; 190:2221-6. [PMID: 18178741 DOI: 10.1128/jb.01753-07] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Enteropathogenic Escherichia coli employs a filamentous type III secretion system, made by homopolymerization of the translocator protein EspA. In this study, we have shown that the N-terminal region of EspA has a role in EspA's protein stability, interaction with the CesAB chaperone, and filament biogenesis and function.
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Rutherford N, Mourez M. Surface display of proteins by gram-negative bacterial autotransporters. Microb Cell Fact 2006; 5:22. [PMID: 16787545 PMCID: PMC1533851 DOI: 10.1186/1475-2859-5-22] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Accepted: 06/20/2006] [Indexed: 11/10/2022] Open
Abstract
Expressing proteins of interest as fusions to proteins of the bacterial envelope is a powerful technique with many biotechnological and medical applications. Autotransporters have recently emerged as a good tool for bacterial surface display. These proteins are composed of an N-terminal signal peptide, followed by a passenger domain and a translocator domain that mediates the outer membrane translocation of the passenger. The natural passenger domain of autotransporters can be replaced by heterologous proteins that become displayed at the bacterial surface by the translocator domain. The simplicity and versatility of this system has made it very attractive and it has been used to display functional enzymes, vaccine antigens as well as polypeptides libraries. The recent advances in the study of the translocation mechanism of autotransporters have raised several controversial issues with implications for their use as display systems. These issues include the requirement for the displayed polypeptides to remain in a translocation-competent state in the periplasm, the requirement for specific signal sequences and "autochaperone" domains, and the influence of the genetic background of the expression host strain. It is therefore important to better understand the mechanism of translocation of autotransporters in order to employ them to their full potential. This review will focus on the recent advances in the study of the translocation mechanism of autotransporters and describe practical considerations regarding their use for bacterial surface display.
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Affiliation(s)
- Nancy Rutherford
- Canada Research Chair on Bacterial Animal Diseases, Université de Montréal, Faculté de Médecine Vétérinaire, 3200 Sicotte, St-Hyacinthe, J2S 7C6, Québec, Canada
| | - Michael Mourez
- Canada Research Chair on Bacterial Animal Diseases, Université de Montréal, Faculté de Médecine Vétérinaire, 3200 Sicotte, St-Hyacinthe, J2S 7C6, Québec, Canada
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Spears KJ, Roe AJ, Gally DL. A comparison of enteropathogenic and enterohaemorrhagic Escherichia coli pathogenesis. FEMS Microbiol Lett 2006; 255:187-202. [PMID: 16448495 DOI: 10.1111/j.1574-6968.2006.00119.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
This review covers enteropathogenic Escherichia coli (EPEC) and enterohaemorrhagic E. coli (EHEC) infections, focusing on differences in their virulence factors and regulation. While Shiga-toxin expression from integrated bacteriophages sets EHEC apart from EPEC, EHEC infections often originate from asymptomatic carriage in ruminants whereas human EPEC are considered to be overt pathogens and more host-restricted. In part, these differences reflect variation in adhesin repertoire, type III-secreted effectors and the way in which these factors are regulated.
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Affiliation(s)
- Kevin J Spears
- Zoonotic and Animal Pathogens Research Laboratory, Centre for Infectious Diseases, Chancellor's Building, University of Edinburgh, Edinburgh, UK
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