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Berndsen ZT, Akhtar M, Thapa M, Vickers T, Schmitz A, Torres JL, Baboo S, Kumar P, Khatoom N, Sheikh A, Hamrick M, Diedrich JK, Martinez-Bartolome S, Garrett PT, Yates JR, Turner JS, Laird RM, Poly F, Porter CK, Copps J, Ellebedy AH, Ward AB, Fleckenstein JM. Repeat modules and N-linked glycans define structure and antigenicity of a critical enterotoxigenic E. coli adhesin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593125. [PMID: 38766097 PMCID: PMC11100705 DOI: 10.1101/2024.05.08.593125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of cases of infectious diarrhea annually, predominantly in children from low-middle income regions. Notably, in children, as well as human volunteers challenged with ETEC, diarrheal severity is significantly increased severity in blood group A (bgA) individuals. EtpA, is a secreted glycoprotein adhesin that functions as a blood group A lectin to promote critical interactions between ETEC and blood group A glycans on intestinal epithelia for effective bacterial adhesion and toxin delivery. EtpA is highly immunogenic resulting in robust antibody responses following natural infection and experimental challenge of human volunteers with ETEC. To understand how EtpA directs ETEC-blood group A interactions and stimulates adaptive immunity, we mutated EtpA, mapped its glycosylation by mass-spectrometry (MS), isolated polyclonal (pAbs) and monoclonal antibodies (mAbs) from vaccinated mice and ETEC-infected human volunteers, and determined structures of antibody-EtpA complexes by cryo-electron microscopy. Both bgA and mAbs that inhibited EtpA-bgA interactions and ETEC adhesion, bound to the C-terminal repeat domain highlighting this region as crucial for ETEC pathogen-host interaction. MS analysis uncovered extensive and heterogeneous N-linked glycosylation of EtpA and cryo-EM structures revealed that mAbs directly engage these unique glycan containing epitopes. Finally, electron microscopy-based polyclonal epitope mapping revealed antibodies targeting numerous distinct epitopes on N and C-terminal domains, suggesting that EtpA vaccination generates responses against neutralizing and decoy regions of the molecule. Collectively, we anticipate that these data will inform our general understanding of pathogen-host glycan interactions and adaptive immunity relevant to rational vaccine subunit design.
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Affiliation(s)
- Zachary T Berndsen
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, USA
| | - Marjahan Akhtar
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
| | - Mahima Thapa
- Department of Pathology and Immunology, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA. Center for Vaccines and Immunity to Microbial Pathogens, Washington University School of Medicine, St Louis, MO, USA and The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St Louis, MO, USA
| | - Tim Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
| | - Aaron Schmitz
- Department of Pathology and Immunology, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA. Center for Vaccines and Immunity to Microbial Pathogens, Washington University School of Medicine, St Louis, MO, USA and The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St Louis, MO, USA
| | - Jonathan L Torres
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, USA
| | - Sabyasachi Baboo
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Pardeep Kumar
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
| | - Nazia Khatoom
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
| | - Alaullah Sheikh
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
| | - Melissa Hamrick
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
| | - Jolene K Diedrich
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | | | - Patrick T Garrett
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - John R Yates
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Jackson S Turner
- Department of Pathology and Immunology, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA. Center for Vaccines and Immunity to Microbial Pathogens, Washington University School of Medicine, St Louis, MO, USA and The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St Louis, MO, USA
| | - Renee M Laird
- Operationally Relevant Infections Department, Naval Medical Research Command (NMRC), Silver Spring, Maryland, USA
| | - Frédéric Poly
- Operationally Relevant Infections Department, Naval Medical Research Command (NMRC), Silver Spring, Maryland, USA
| | - Chad K Porter
- Naval Medical Research Command (NMRC), Silver Spring, Maryland, USA
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Jeffrey Copps
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, USA
| | - Ali H Ellebedy
- Department of Pathology and Immunology, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA. Center for Vaccines and Immunity to Microbial Pathogens, Washington University School of Medicine, St Louis, MO, USA and The Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, St Louis, MO, USA
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA, USA
| | - James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University in Saint Louis, School of Medicine. Saint Louis, Missouri, USA
- Medicine Service, Infectious Diseases, Veterans Affairs Health Care System, Saint Louis Missouri, USA
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2
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Kuhlmann FM, Grigura V, Vickers TJ, Prouty MG, Iannotti LL, Dulience SJL, Fleckenstein JM. Seroprevalence Study of Conserved Enterotoxigenic Escherichia coli Antigens in Globally Diverse Populations. Microorganisms 2023; 11:2221. [PMID: 37764065 PMCID: PMC10536235 DOI: 10.3390/microorganisms11092221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/28/2023] [Accepted: 08/30/2023] [Indexed: 09/29/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) are common causes of infectious diarrhea among young children of low-and middle-income countries (LMICs) and travelers to these regions. Despite their significant contributions to the morbidity and mortality associated with childhood and traveler's diarrhea, no licensed vaccines are available. Current vaccine strategies may benefit from the inclusion of additional conserved antigens, which may contribute to broader coverage and enhanced efficacy, given their key roles in facilitating intestinal colonization and effective enterotoxin delivery. EatA and EtpA are widely conserved in diverse populations of ETEC, but their immunogenicity has only been studied in controlled human infection models and a population of children in Bangladesh. Here, we compared serologic responses to EatA, EtpA and heat-labile toxin in populations from endemic regions including Haitian children and subjects residing in Egypt, Cameroon, and Peru to US children and adults where ETEC infections are sporadic. We observed elevated IgG and IgA responses in individuals from endemic regions to each of the antigens studied. In a cohort of Haitian children, we observed increased immune responses following exposure to each of the profiled antigens. These findings reflect the wide distribution of ETEC infections across multiple endemic regions and support further evaluation of EatA and EtpA as candidate ETEC vaccine antigens.
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Affiliation(s)
- Frederick Matthew Kuhlmann
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
| | - Vadim Grigura
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
| | - Timothy J. Vickers
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
| | | | - Lora L. Iannotti
- Institute for Public Health, Brown School, Washington University in Saint Louis, Saint Louis, MO 63110, USA; (L.L.I.); (S.J.L.D.)
| | - Sherlie Jean Louis Dulience
- Institute for Public Health, Brown School, Washington University in Saint Louis, Saint Louis, MO 63110, USA; (L.L.I.); (S.J.L.D.)
| | - James M. Fleckenstein
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine in Saint Louis, Saint Louis, MO 63110, USA; (F.M.K.); (V.G.); (T.J.V.)
- Medicine Service, Infectious Diseases, Saint Louis VA Health Care System, St. Louis, MO 63110, USA
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3
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Sheikh A, Wangdi T, Vickers TJ, Aaron B, Palmer M, Miller MJ, Kim S, Herring C, Simoes R, Crainic JA, Gildersleeve JC, van der Post S, Hansson GC, Fleckenstein JM. Enterotoxigenic Escherichia coli Degrades the Host MUC2 Mucin Barrier To Facilitate Critical Pathogen-Enterocyte Interactions in Human Small Intestine. Infect Immun 2022; 90:e0057221. [PMID: 34807735 PMCID: PMC8853678 DOI: 10.1128/iai.00572-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 11/12/2021] [Indexed: 02/08/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) isolates are genetically diverse pathological variants of E. coli defined by the production of heat-labile (LT) and/or heat-stable (ST) toxins. ETEC strains are estimated to cause hundreds of millions of cases of diarrheal illness annually. However, it is not clear that all strains are equally equipped to cause disease, and asymptomatic colonization with ETEC is common in low- to middle-income regions lacking basic sanitation and clean water where ETEC are ubiquitous. Recent molecular epidemiology studies have revealed a significant association between strains that produce EatA, a secreted autotransporter protein, and the development of symptomatic infection. Here, we demonstrate that LT stimulates production of MUC2 mucin by goblet cells in human small intestine, enhancing the protective barrier between pathogens and enterocytes. In contrast, using explants of human small intestine as well as small intestinal enteroids, we show that EatA counters this host defense by engaging and degrading the MUC2 mucin barrier to promote bacterial access to target enterocytes and ultimately toxin delivery, suggesting that EatA plays a crucial role in the molecular pathogenesis of ETEC. These findings may inform novel approaches to prevention of acute diarrheal illness as well as the sequelae associated with ETEC and other pathogens that rely on EatA and similar proteases for efficient interaction with their human hosts.
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Affiliation(s)
- Alaullah Sheikh
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Tamding Wangdi
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Tim J. Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Bailey Aaron
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Margot Palmer
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Mark J. Miller
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Seonyoung Kim
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Cassandra Herring
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Rita Simoes
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Jennifer A. Crainic
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Jeffrey C. Gildersleeve
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Sjoerd van der Post
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Gunnar C. Hansson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri, USA
- Medicine Service, Veterans Affairs Medical Center, Saint Louis, Missouri, USA
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4
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Kuhlmann FM, Martin J, Hazen TH, Vickers TJ, Pashos M, Okhuysen PC, Gómez-Duarte OG, Cebelinski E, Boxrud D, del Canto F, Vidal R, Qadri F, Mitreva M, Rasko DA, Fleckenstein JM. Conservation and global distribution of non-canonical antigens in Enterotoxigenic Escherichia coli. PLoS Negl Trop Dis 2019; 13:e0007825. [PMID: 31756188 PMCID: PMC6897418 DOI: 10.1371/journal.pntd.0007825] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/06/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Enterotoxigenic Escherichia coli (ETEC) cause significant diarrheal morbidity and mortality in children of resource-limited regions, warranting development of effective vaccine strategies. Genetic diversity of the ETEC pathovar has impeded development of broadly protective vaccines centered on the classical canonical antigens, the colonization factors and heat-labile toxin. Two non-canonical ETEC antigens, the EtpA adhesin, and the EatA mucinase are immunogenic in humans and protective in animal models. To foster rational vaccine design that complements existing strategies, we examined the distribution and molecular conservation of these antigens in a diverse population of ETEC isolates. METHODS Geographically diverse ETEC isolates (n = 1159) were interrogated by PCR, immunoblotting, and/or whole genome sequencing (n = 46) to examine antigen conservation. The most divergent proteins were purified and their core functions assessed in vitro. RESULTS EatA and EtpA or their coding sequences were present in 57.0% and 51.5% of the ETEC isolates overall, respectively; and were globally dispersed without significant regional differences in antigen distribution. These antigens also exhibited >93% amino acid sequence identity with even the most divergent proteins retaining the core adhesin and mucinase activity assigned to the prototype molecules. CONCLUSIONS EtpA and EatA are well-conserved molecules in the ETEC pathovar, suggesting that they serve important roles in virulence and that they could be exploited for rational vaccine design.
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Affiliation(s)
- F. Matthew Kuhlmann
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
| | - John Martin
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Tracy H. Hazen
- Department of Microbiology and Immunology and Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Tim J. Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Madeline Pashos
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Pablo C. Okhuysen
- The Department of Infectious Diseases, Infection Control and Employee Health, University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Oscar G. Gómez-Duarte
- Department of Pediatrics, Division of Infectious Diseases, University at Buffalo, The State University of New York, Buffalo, New York, United States of America
| | | | - Dave Boxrud
- Minnesota Department of Health, St. Paul, Minnesota, United States of America
| | - Felipe del Canto
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Roberto Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- Instituto Milenio de Inmunonología e Inmunoterapia, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Makedonka Mitreva
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - David A. Rasko
- Department of Microbiology and Immunology and Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, United States of America
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5
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Chakraborty S, Randall A, Vickers TJ, Molina D, Harro CD, DeNearing B, Brubaker J, Sack DA, Bourgeois AL, Felgner PL, Liang X, Mani S, Wenzel H, Townsend RR, Gilmore PE, Darsley MJ, Rasko DA, Fleckenstein JM. Interrogation of a live-attenuated enterotoxigenic Escherichia coli vaccine highlights features unique to wild-type infection. NPJ Vaccines 2019; 4:37. [PMID: 31482013 PMCID: PMC6713706 DOI: 10.1038/s41541-019-0131-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 08/01/2019] [Indexed: 01/01/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) infections are a common cause of severe diarrheal illness in low- and middle-income countries. The live-attenuated ACE527 ETEC vaccine, adjuvanted with double mutant heat-labile toxin (dmLT), affords clear but partial protection against ETEC challenge in human volunteers. Comparatively, initial wild-type ETEC challenge completely protects against severe diarrhea on homologous re-challenge. To investigate determinants of protection, vaccine antigen content was compared to wild-type ETEC, and proteome microarrays were used to assess immune responses following vaccination and ETEC challenge. Although molecular interrogation of the vaccine confirmed expression of targeted canonical antigens, relative to wild-type ETEC, vaccine strains were deficient in production of flagellar antigens, immotile, and lacked production of the EtpA adhesin. Similarly, vaccination ± dmLT elicited responses to targeted canonical antigens, but relative to wild-type challenge, vaccine responses to some potentially protective non-canonical antigens including EtpA and the YghJ metalloprotease were diminished or absent. These studies highlight important differences in vaccine and wild-type ETEC antigen content and call attention to distinct immunologic signatures that could inform investigation of correlates of protection, and guide vaccine antigen selection for these pathogens of global importance.
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Affiliation(s)
| | | | - Tim J. Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO USA
| | - Doug Molina
- Antigen Discovery, Inc. (ADI), Irvine, CA USA
| | - Clayton D. Harro
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD USA
| | | | - Jessica Brubaker
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD USA
| | - David A. Sack
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD USA
| | | | - Philip L. Felgner
- Antigen Discovery, Inc. (ADI), Irvine, CA USA
- Vaccine R & D Center, University of California, Irvine, Irvine, CA USA
| | | | - Sachin Mani
- Enteric Vaccine Initiative, PATH, Washington DC, USA
| | | | - R. Reid Townsend
- Department of Medicine, Divsion of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St. Louis, USA
| | - Petra E. Gilmore
- Department of Medicine, Divsion of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St. Louis, USA
| | | | - David A. Rasko
- The Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD USA
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, MO USA
- Medicine Service, John Cochran VA Medical Center, St. Louis, MO USA
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6
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Chakraborty S, Randall A, Vickers TJ, Molina D, Harro CD, DeNearing B, Brubaker J, Sack DA, Bourgeois AL, Felgner PL, Liang X, Mani S, Wenzel H, Townsend RR, Gilmore PE, Darsley MJ, Rasko DA, Fleckenstein JM. Human Experimental Challenge With Enterotoxigenic Escherichia coli Elicits Immune Responses to Canonical and Novel Antigens Relevant to Vaccine Development. J Infect Dis 2018; 218:1436-1446. [PMID: 29800314 PMCID: PMC6151082 DOI: 10.1093/infdis/jiy312] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 05/22/2018] [Indexed: 11/12/2022] Open
Abstract
Background Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrheal illness in the developing world. Enterotoxigenic E coli vaccinology has been challenged by genetic diversity and heterogeneity of canonical antigens. Examination of the antigenic breadth of immune responses associated with protective immunity could afford new avenues for vaccine development. Methods Antibody lymphocyte supernatants (ALS) and sera from 20 naive human volunteers challenged with ETEC strain H10407 and from 10 volunteers rechallenged 4-6 weeks later with the same strain (9 of whom were completely protected on rechallenge) were tested against ETEC proteome microarrays containing 957 antigens. Results Enterotoxigenic E coli challenge stimulated robust serum and mucosal (ALS) responses to canonical vaccine antigens (CFA/I, and the B subunit of LT) as well as a small number of antigens not presently targeted in ETEC vaccines. These included pathovar-specific secreted proteins (EtpA, EatA) as well as highly conserved E coli antigens including YghJ, flagellin, and pertactin-like autotransporter proteins, all of which have previously afforded protection against ETEC infection in preclinical studies. Conclusions Taken together, studies reported here suggest that immune responses after ETEC infection involve traditional vaccine targets as well as a select number of more recently identified protein antigens that could offer additional avenues for vaccine development for these pathogens.
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Affiliation(s)
| | - Arlo Randall
- Antigen Discovery, Inc. (ADI), Irvine, California
| | - Tim J Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri
| | - Doug Molina
- Antigen Discovery, Inc. (ADI), Irvine, California
| | - Clayton D Harro
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Barbara DeNearing
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Jessica Brubaker
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - David A Sack
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | | | - Xiaowu Liang
- Antigen Discovery, Inc. (ADI), Irvine, California
| | | | | | - R Reid Townsend
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine
| | - Petra E Gilmore
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine
| | | | - David A Rasko
- The Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland
| | - James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, Saint Louis, Missouri
- Medicine Service, John Cochran VA Medical Center, St. Louis, Missouri
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7
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Kumar P, Kuhlmann FM, Chakraborty S, Bourgeois AL, Foulke-Abel J, Tumala B, Vickers TJ, Sack DA, DeNearing B, Harro CD, Wright WS, Gildersleeve JC, Ciorba MA, Santhanam S, Porter CK, Gutierrez RL, Prouty MG, Riddle MS, Polino A, Sheikh A, Donowitz M, Fleckenstein JM. Enterotoxigenic Escherichia coli-blood group A interactions intensify diarrheal severity. J Clin Invest 2018; 128:3298-3311. [PMID: 29771685 DOI: 10.1172/jci97659] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 05/03/2018] [Indexed: 12/27/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) infections are highly prevalent in developing countries, where clinical presentations range from asymptomatic colonization to severe cholera-like illness. The molecular basis for these varied presentations, which may involve strain-specific virulence features as well as host factors, has not been elucidated. We demonstrate that, when challenged with ETEC strain H10407, originally isolated from a case of cholera-like illness, blood group A human volunteers developed severe diarrhea more frequently than individuals from other blood groups. Interestingly, a diverse population of ETEC strains, including H10407, secrete the EtpA adhesin molecule. As many bacterial adhesins also agglutinate red blood cells, we combined the use of glycan arrays, biolayer inferometry, and noncanonical amino acid labeling with hemagglutination studies to demonstrate that EtpA is a dominant ETEC blood group A-specific lectin/hemagglutinin. Importantly, we have also shown that EtpA interacts specifically with glycans expressed on intestinal epithelial cells from blood group A individuals and that EtpA-mediated bacterial-host interactions accelerate bacterial adhesion and effective delivery of both the heat-labile and heat-stable toxins of ETEC. Collectively, these data provide additional insight into the complex molecular basis of severe ETEC diarrheal illness that may inform rational design of vaccines to protect those at highest risk.
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Affiliation(s)
- Pardeep Kumar
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - F Matthew Kuhlmann
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - A Louis Bourgeois
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jennifer Foulke-Abel
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Brunda Tumala
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Tim J Vickers
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA
| | - David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Barbara DeNearing
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Clayton D Harro
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - W Shea Wright
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Jeffrey C Gildersleeve
- Center for Cancer Research, Chemical Biology Laboratory, National Cancer Institute, Fredrick, Maryland, USA
| | - Matthew A Ciorba
- Department of Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Srikanth Santhanam
- Department of Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Chad K Porter
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Ramiro L Gutierrez
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Michael G Prouty
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Mark S Riddle
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, Maryland, USA
| | - Alexander Polino
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alaullah Sheikh
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Mark Donowitz
- Department of Medicine, Division of Gastroenterology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - James M Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, USA.,Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, USA.,Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, USA
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Dynamic Interactions of a Conserved Enterotoxigenic Escherichia coli Adhesin with Intestinal Mucins Govern Epithelium Engagement and Toxin Delivery. Infect Immun 2016; 84:3608-3617. [PMID: 27736776 PMCID: PMC5116737 DOI: 10.1128/iai.00692-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/02/2016] [Indexed: 12/30/2022] Open
Abstract
At present, there is no vaccine for enterotoxigenic Escherichia coli (ETEC), an important cause of diarrheal illness. Nevertheless, recent microbial pathogenesis studies have identified a number of molecules produced by ETEC that contribute to its virulence and are novel antigenic targets to complement canonical vaccine approaches. EtpA is a secreted two-partner adhesin that is conserved within the ETEC pathovar. EtpA interacts with the tips of ETEC flagella to promote bacterial adhesion, toxin delivery, and intestinal colonization by forming molecular bridges between the bacteria and the epithelial surface. However, the nature of EtpA interactions with the intestinal epithelium remains poorly defined. Here, we demonstrate that EtpA interacts with glycans presented by transmembrane and secreted intestinal mucins at epithelial surfaces to facilitate pathogen-host interactions that culminate in toxin delivery. Moreover, we found that a major effector molecule of ETEC, the heat-labile enterotoxin (LT), may enhance these interactions by stimulating the production of the gel-forming mucin MUC2. Our studies suggest, however, that EtpA participates in complex and dynamic interactions between ETEC and the gastrointestinal mucosae in which host glycoproteins promote bacterial attachment while simultaneously limiting the epithelial engagement required for effective toxin delivery. Collectively, these data provide additional insight into the intricate nature of ETEC interactions with the intestinal epithelium that have potential implications for rational approaches to vaccine design.
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Immunogenicity and Protective Efficacy against Enterotoxigenic Escherichia coli Colonization following Intradermal, Sublingual, or Oral Vaccination with EtpA Adhesin. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:628-37. [PMID: 27226279 DOI: 10.1128/cvi.00248-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 05/17/2016] [Indexed: 12/16/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) strains are a common cause of diarrhea. Extraordinary antigenic diversity has prompted a search for conserved antigens to complement canonical approaches to ETEC vaccine development. EtpA, an immunogenic extracellular ETEC adhesin relatively conserved in the ETEC pathovar, has previously been shown to be a protective antigen following intranasal immunization. These studies were undertaken to explore alternative routes of EtpA vaccination that would permit use of a double mutant (R192G L211A) heat-labile toxin (dmLT) adjuvant. Here, oral vaccination with EtpA adjuvanted with dmLT afforded significant protection against small intestinal colonization, and the degree of protection correlated with fecal IgG, IgA, or total fecal antibody responses to EtpA. Sublingual vaccination yielded compartmentalized mucosal immune responses with significant increases in anti-EtpA fecal IgG and IgA, and mice vaccinated via this route were also protected against colonization. In contrast, while intradermal (i.d.) vaccination achieved high levels of both serum and fecal antibodies against both EtpA and dmLT, mice vaccinated via the i.d. route were not protected against subsequent colonization and the avidity of serum IgG and IgA EtpA-specific antibodies was significantly lower after i.d. immunization compared to other routes. Finally, we demonstrate that antiserum from vaccinated mice significantly impairs binding of LT to cognate GM1 receptors and shows near complete neutralization of toxin delivery by ETEC in vitro Collectively, these data provide further evidence that EtpA could complement future vaccine strategies but also suggest that additional effort will be required to optimize its use as a protective immunogen.
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10
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Hu Z, Chen Z, Huang N, Teng X, Zhang J, Wang Z, Wei X, Qin K, Liu X, Wu X, Tang H, Zhu X, Cui K, Li J. Expression, purification of IL-38 in Escherichia coli and production of polyclonal antibodies. Protein Expr Purif 2015; 107:76-82. [DOI: 10.1016/j.pep.2014.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/28/2014] [Accepted: 10/30/2014] [Indexed: 12/31/2022]
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11
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Luo Q, Qadri F, Kansal R, Rasko DA, Sheikh A, Fleckenstein JM. Conservation and immunogenicity of novel antigens in diverse isolates of enterotoxigenic Escherichia coli. PLoS Negl Trop Dis 2015; 9:e0003446. [PMID: 25629897 PMCID: PMC4309559 DOI: 10.1371/journal.pntd.0003446] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 11/26/2014] [Indexed: 12/12/2022] Open
Abstract
Background Enterotoxigenic Escherichia coli (ETEC) are common causes of diarrheal morbidity and mortality in developing countries for which there is currently no vaccine. Heterogeneity in classical ETEC antigens known as colonization factors (CFs) and poor efficacy of toxoid-based approaches to date have impeded development of a broadly protective ETEC vaccine, prompting searches for novel molecular targets. Methodology Using a variety of molecular methods, we examined a large collection of ETEC isolates for production of two secreted plasmid-encoded pathotype-specific antigens, the EtpA extracellular adhesin, and EatA, a mucin-degrading serine protease; and two chromosomally-encoded molecules, the YghJ metalloprotease and the EaeH adhesin, that are not specific to the ETEC pathovar, but which have been implicated in ETEC pathogenesis. ELISA assays were also performed on control and convalescent sera to characterize the immune response to these antigens. Finally, mice were immunized with recombinant EtpA (rEtpA), and a protease deficient version of the secreted EatA passenger domain (rEatApH134R) to examine the feasibility of combining these molecules in a subunit vaccine approach. Principal Findings EtpA and EatA were secreted by more than half of all ETEC, distributed over diverse phylogenetic lineages belonging to multiple CF groups, and exhibited surprisingly little sequence variation. Both chromosomally-encoded molecules were also identified in a wide variety of ETEC strains and YghJ was secreted by 89% of isolates. Antibodies against both the ETEC pathovar-specific and conserved E. coli antigens were present in significantly higher titers in convalescent samples from subjects with ETEC infection than controls suggesting that each of these antigens is produced and recognized during infection. Finally, co-immunization of mice with rEtpA and rEatApH134R offered significant protection against ETEC infection. Conclusions Collectively, these data suggest that novel antigens could significantly complement current approaches and foster improved strategies for development of broadly protective ETEC vaccines. Infectious diarrhea is one of the leading causes of death among young children in developing countries, and a major cause of morbidity in all age groups. The enterotoxigenic Escherichia coli contribute substantially to this burden of diarrheal illness, and have been a focus of vaccine development efforts for more than forty years following their discovery as a cause of severe diarrheal illness. The heat-labile, and/or heat stable enterotoxins that define ETEC are produced by a diverse population of Escherichia coli. This inherent genetic plasticity of E. coli has made it difficult to identify antigens specific to ETEC that are highly conserved. Therefore, identification of protective antigens shared by many ETEC strains will likely play an essential role in development of the next iteration of vaccines.
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Affiliation(s)
- Qingwei Luo
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research, Bangladesh, Mohakhali, Dhaka, Bangladesh
| | - Rita Kansal
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - David A. Rasko
- Institute for Genome Sciences, Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alaullah Sheikh
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - James M. Fleckenstein
- Department of Medicine, Division of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Molecular Microbiology and Microbial Pathogenesis Program, Division of Biology and Biomedical Sciences, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Medicine Service, Veterans Affairs Medical Center, St. Louis, Missouri, United States of America
- * E-mail:
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12
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Cooperative role of antibodies against heat-labile toxin and the EtpA Adhesin in preventing toxin delivery and intestinal colonization by enterotoxigenic Escherichia coli. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 19:1603-8. [PMID: 22875600 DOI: 10.1128/cvi.00351-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrheal disease in developing countries, where it is responsible for hundreds of thousands of deaths each year. Vaccine development for ETEC has been hindered by the heterogeneity of known molecular targets and the lack of broad-based sustained protection afforded by existing vaccine strategies. In an effort to explore the potential role of novel antigens in ETEC vaccines, we examined the ability of antibodies directed against the ETEC heat-labile toxin (LT) and the recently described EtpA adhesin to prevent intestinal colonization in vivo and toxin delivery to epithelial cells in vitro. We demonstrate that EtpA is required for the optimal delivery of LT and that antibodies against this adhesin play at least an additive role in preventing delivery of LT to target intestinal cells when combined with antibodies against either the A or B subunits of the toxin. Moreover, vaccination with a combination of LT and EtpA significantly impaired intestinal colonization. Together, these results suggest that the incorporation of recently identified molecules such as EtpA could be used to enhance current approaches to ETEC vaccine development.
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13
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Outer membrane vesicles induce immune responses to virulence proteins and protect against colonization by enterotoxigenic Escherichia coli. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:1803-8. [PMID: 21900530 DOI: 10.1128/cvi.05217-11] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Enterotoxigenic Escherichia coli (ETEC) strains are a heterogeneous group of pathogens that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Collectively, these pathogens are responsible for hundreds of thousands of deaths annually in developing countries, particularly in children under the age of 5 years. The heterogeneity of previously investigated molecular targets and the lack of complete sustained protection afforded by antitoxin immunity have impeded progress to date toward a broadly protective vaccine. Many pathogens, including ETEC, have the capacity to form outer membrane vesicles (OMV), which often contain one or more virulence proteins. Prompted by recent studies that identified several immunogenic virulence proteins in outer membrane vesicles of ETEC, we sought to examine the immunogenicity and protective efficacy of these structures in a murine model of infection. Here we demonstrate that immunization with OMV impairs ETEC colonization of the small intestine and stimulates antibodies that recognize the heat-labile toxin and two additional putative virulence proteins, the EtpA adhesin and CexE. Similar to earlier studies with EtpA, vaccination with LT alone also inhibited intestinal colonization. Together, these findings suggest that OMV could be exploited to deliver protective antigens relevant to development of ETEC vaccines.
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Roy K, Kansal R, Bartels SR, Hamilton DJ, Shaaban S, Fleckenstein JM. Adhesin degradation accelerates delivery of heat-labile toxin by enterotoxigenic Escherichia coli. J Biol Chem 2011; 286:29771-9. [PMID: 21757737 PMCID: PMC3191018 DOI: 10.1074/jbc.m111.251546] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Revised: 07/07/2011] [Indexed: 12/12/2022] Open
Abstract
Many enteric pathogens, including enterotoxigenic Escherichia coli (ETEC), produce one or more serine proteases that are secreted via the autotransporter (or type V) bacterial secretion pathway. These molecules have collectively been referred to as SPATE proteins (serine protease autotransporter of the Enterobacteriaceae). EatA, an autotransporter previously identified in ETEC, possesses a functional serine protease motif within its secreted amino-terminal passenger domain. Although this protein is expressed by many ETEC strains and is highly immunogenic, its precise function is unknown. Here, we demonstrate that EatA degrades a recently characterized adhesin, EtpA, resulting in modulation of bacterial adhesion and accelerated delivery of the heat-labile toxin, a principal ETEC virulence determinant. Antibodies raised against the passenger domain of EatA impair ETEC delivery of labile toxin to epithelial cells suggesting that EatA may be an effective target for vaccine development.
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Affiliation(s)
| | - Rita Kansal
- Research Services, Veterans Affairs Medical Center, Memphis, Tennessee 38104, and
| | | | | | - Salwa Shaaban
- the Faculty of Pharmacy, Beni-Sueif University, 62514 Beni-Sueif, Egypt
| | - James M. Fleckenstein
- From the Departments of Medicine
- Molecular Sciences, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163
- the Medicine and
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Enterotoxigenic Escherichia coli elicits immune responses to multiple surface proteins. Infect Immun 2010; 78:3027-35. [PMID: 20457787 DOI: 10.1128/iai.00264-10] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) causes considerable morbidity and mortality due to diarrheal illness in developing countries, particularly in young children. Despite the global importance of these heterogeneous pathogens, a broadly protective vaccine is not yet available. While much is known regarding the immunology of well-characterized virulence proteins, in particular the heat-labile toxin (LT) and colonization factors (CFs), to date, evaluation of the immune response to other antigens has been limited. However, the availability of genomic DNA sequences for ETEC strains coupled with proteomics technology affords opportunities to examine novel uncharacterized antigens that might also serve as targets for vaccine development. Analysis of whole or fractionated bacterial proteomes with convalescent-phase sera can potentially accelerate identification of secreted or surface-expressed targets that are recognized during the course of infection. Here we report results of an immunoproteomics approach to antigen discovery with ETEC strain H10407. Immunoblotting of proteins separated by two-dimensional electrophoresis (2DE) with sera from mice infected with strain H10407 or with convalescent human sera obtained following natural ETEC infections demonstrated multiple immunoreactive molecules in culture supernatant, outer membrane, and outer membrane vesicle preparations, suggesting that many antigens are recognized during the course of infection. Proteins identified by this approach included established virulence determinants, more recently identified putative virulence factors, as well as novel secreted and outer membrane proteins. Together, these studies suggest that existing and emerging proteomics technologies can provide a useful complement to ongoing approaches to ETEC vaccine development.
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