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Pokharel P, Dhakal S, Dozois CM. The Diversity of Escherichia coli Pathotypes and Vaccination Strategies against This Versatile Bacterial Pathogen. Microorganisms 2023; 11:344. [PMID: 36838308 PMCID: PMC9965155 DOI: 10.3390/microorganisms11020344] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 01/24/2023] [Accepted: 01/25/2023] [Indexed: 02/03/2023] Open
Abstract
Escherichia coli (E. coli) is a gram-negative bacillus and resident of the normal intestinal microbiota. However, some E. coli strains can cause diseases in humans, other mammals and birds ranging from intestinal infections, for example, diarrhea and dysentery, to extraintestinal infections, such as urinary tract infections, respiratory tract infections, meningitis, and sepsis. In terms of morbidity and mortality, pathogenic E. coli has a great impact on public health, with an economic cost of several billion dollars annually worldwide. Antibiotics are not usually used as first-line treatment for diarrheal illness caused by E. coli and in the case of bloody diarrhea, antibiotics are avoided due to the increased risk of hemolytic uremic syndrome. On the other hand, extraintestinal infections are treated with various antibiotics depending on the site of infection and susceptibility testing. Several alarming papers concerning the rising antibiotic resistance rates in E. coli strains have been published. The silent pandemic of multidrug-resistant bacteria including pathogenic E. coli that have become more difficult to treat favored prophylactic approaches such as E. coli vaccines. This review provides an overview of the pathogenesis of different pathotypes of E. coli, the virulence factors involved and updates on the major aspects of vaccine development against different E. coli pathotypes.
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Affiliation(s)
- Pravil Pokharel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), 531 Boul des Prairies, Laval, QC H7V 1B7, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Sabin Dhakal
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), 531 Boul des Prairies, Laval, QC H7V 1B7, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Charles M. Dozois
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique (INRS), 531 Boul des Prairies, Laval, QC H7V 1B7, Canada
- Centre de Recherche en Infectiologie Porcine et Avicole (CRIPA), Faculté de Médecine Vétérinaire, Université de Montréal Saint-Hyacinthe, Saint-Hyacinthe, QC J2S 2M2, Canada
- Pasteur Network, Laval, QC H7V 1B7, Canada
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Rojas-Lopez M, Monterio R, Pizza M, Desvaux M, Rosini R. Intestinal Pathogenic Escherichia coli: Insights for Vaccine Development. Front Microbiol 2018; 9:440. [PMID: 29615989 PMCID: PMC5869917 DOI: 10.3389/fmicb.2018.00440] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 02/26/2018] [Indexed: 12/13/2022] Open
Abstract
Diarrheal diseases are one of the major causes of mortality among children under five years old and intestinal pathogenic Escherichia coli (InPEC) plays a role as one of the large causative groups of these infections worldwide. InPECs contribute significantly to the burden of intestinal diseases, which are a critical issue in low- and middle-income countries (Asia, Africa and Latin America). Intestinal pathotypes such as enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli (ETEC) are mainly endemic in developing countries, while ETEC strains are the major cause of diarrhea in travelers to these countries. On the other hand, enterohemorrhagic E. coli (EHEC) are the cause of large outbreaks around the world, mainly affecting developed countries and responsible for not only diarrheal disease but also severe clinical complications like hemorrhagic colitis and hemolytic uremic syndrome (HUS). Overall, the emergence of antibiotic resistant strains, the annual cost increase in the health care system, the high incidence of traveler diarrhea and the increased number of HUS episodes have raised the need for effective preventive treatments. Although the use of antibiotics is still important in treating such infections, non-antibiotic strategies are either a crucial option to limit the increase in antibiotic resistant strains or absolutely necessary for diseases such as those caused by EHEC infections, for which antibiotic therapies are not recommended. Among non-antibiotic therapies, vaccine development is a strategy of choice but, to date, there is no effective licensed vaccine against InPEC infections. For several years, there has been a sustained effort to identify efficacious vaccine candidates able to reduce the burden of diarrheal disease. The aim of this review is to summarize recent milestones and insights in vaccine development against InPECs.
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Affiliation(s)
- Maricarmen Rojas-Lopez
- GSK, Siena, Italy.,Institut National de la Recherche Agronomique, Université Clermont Auvergne, UMR454 MEDiS, Clermont-Ferrand, France
| | - Ricardo Monterio
- Institut National de la Recherche Agronomique, Université Clermont Auvergne, UMR454 MEDiS, Clermont-Ferrand, France
| | | | - Mickaël Desvaux
- Institut National de la Recherche Agronomique, Université Clermont Auvergne, UMR454 MEDiS, Clermont-Ferrand, France
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Surface expression of Helicobacter pylori HpaA adhesion antigen on Vibrio cholerae, enhanced by co-expressed enterotoxigenic Escherichia coli fimbrial antigens. Microb Pathog 2017; 105:177-184. [PMID: 28215587 DOI: 10.1016/j.micpath.2017.02.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 02/11/2017] [Accepted: 02/13/2017] [Indexed: 12/23/2022]
Abstract
Helicobacter pylori infection can cause peptic ulceration and is associated with gastric adenocarcinoma. This study aimed to construct and characterize a non-virulent Vibrio cholerae O1 strain, which grows more rapidly than H. pylori, as vector for H. pylori antigens for possible use as a vaccine strain against H. pylori. This was done by recombinant expression of the H. pylori adhesion antigen HpaA alone or, as a proof of principle, together with different colonization factor (CF) antigens of enterotoxigenic Escherichia coli (ETEC) which may enhance immune responses against HpaA. A recombinant V. cholerae strain co-expressing HpaA and a fimbrial CF antigens CFA/I or CS5, but not the non-fimbrial CF protein CS6, was shown to express larger amounts of HpaA on the surface when compared with the same V. cholerae strain expressing HpaA alone. Mutations in the CFA/I operon showed that the chaperon, possibly together with the usher, was involved in enhancing the surface expression of HpaA. Oral immunization of mice with formaldehyde-inactivated recombinant V. cholerae expressing HpaA alone or together with CFA/I induced significantly higher serum antibody responses against HpaA than mice similarly immunized with inactivated HpaA-expressing H. pylori bacteria. Our results demonstrate that a non-virulent V. cholerae strain can be engineered to allow strong surface expression of HpaA, and that the expression can be further increased by co-expressing it with ETEC fimbrial antigens. Such recombinant V. cholerae strains expressing HpaA, and possibly also other H. pylori antigens, may have the potential as oral inactivated vaccine candidates against H. pylori.
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Preparation and preclinical evaluation of a freeze-dried formulation of a novel combined multivalent whole-cell/B-subunit oral vaccine against enterotoxigenic Escherichia coli diarrhea. Eur J Pharm Biopharm 2016; 108:18-24. [DOI: 10.1016/j.ejpb.2016.07.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 05/04/2016] [Accepted: 07/10/2016] [Indexed: 11/22/2022]
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Tobias J, Von Mentzer A, Loayza Frykberg P, Aslett M, Page AJ, Sjöling Å, Svennerholm AM. Stability of the Encoding Plasmids and Surface Expression of CS6 Differs in Enterotoxigenic Escherichia coli (ETEC) Encoding Different Heat-Stable (ST) Enterotoxins (STh and STp). PLoS One 2016; 11:e0152899. [PMID: 27054573 PMCID: PMC4824445 DOI: 10.1371/journal.pone.0152899] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 03/21/2016] [Indexed: 12/01/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC), one of the most common reasons of diarrhea among infants and children in developing countries, causes disease by expression of either or both of the enterotoxins heat-labile (LT) and heat-stable (ST; divided into human-type [STh] and porcine-type [STp] variants), and colonization factors (CFs) among which CS6 is one of the most prevalent ETEC CFs. In this study we show that ETEC isolates expressing CS6+STh have higher copy numbers of the cssABCD operon encoding CS6 than those expressing CS6+STp. Long term cultivation of up to ten over-night passages of ETEC isolates harboring CS6+STh (n = 10) or CS6+STp (n = 15) showed instability of phenotypic expression of CS6 in a majority of the CS6+STp isolates, whereas most of the CS6+STh isolates retained CS6 expression. The observed instability was a correlated with loss of genes cssA and cssD as examined by PCR. Mobilization of the CS6 plasmid from an unstable CS6+STp isolate into a laboratory E. coli strain resulted in loss of the plasmid after a single over-night passage whereas the plasmid from an CS6+STh strain was retained in the laboratory strain during 10 passages. A sequence comparison between the CS6 plasmids from a stable and an unstable ETEC isolate revealed that genes necessary for plasmid stabilization, for example pemI, pemK, stbA, stbB and parM, were not present in the unstable ETEC isolate. Our results indicate that stable retention of CS6 may in part be affected by the stability of the plasmid on which both CS6 and STp or STh are located.
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Affiliation(s)
- Joshua Tobias
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, S-40530, Göteborg, Sweden
- * E-mail:
| | - Astrid Von Mentzer
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, S-40530, Göteborg, Sweden
| | - Patricia Loayza Frykberg
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, S-40530, Göteborg, Sweden
| | - Martin Aslett
- Pathogen Genomics, Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Andrew J. Page
- Pathogen Genomics, Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, United Kingdom
| | - Åsa Sjöling
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, S-40530, Göteborg, Sweden
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, S-171 77, Stockholm, Sweden
| | - Ann-Mari Svennerholm
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, S-40530, Göteborg, Sweden
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Leitner DR, Lichtenegger S, Temel P, Zingl FG, Ratzberger D, Roier S, Schild-Prüfert K, Feichter S, Reidl J, Schild S. A combined vaccine approach against Vibrio cholerae and ETEC based on outer membrane vesicles. Front Microbiol 2015; 6:823. [PMID: 26322032 PMCID: PMC4531250 DOI: 10.3389/fmicb.2015.00823] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 07/27/2015] [Indexed: 11/28/2022] Open
Abstract
Enteric infections induced by pathogens like Vibrio cholerae and enterotoxigenic Escherichia coli (ETEC) remain a massive burden in developing countries with increasing morbidity and mortality rates. Previously, we showed that the immunization with genetically detoxified outer membrane vesicles (OMVs) derived from V. cholerae elicits a protective immune response based on the generation of O antigen antibodies, which effectively block the motility by binding to the sheathed flagellum. In this study, we investigated the potential of lipopolysaccharide (LPS)-modified and toxin negative OMVs isolated from V. cholerae and ETEC as a combined OMV vaccine candidate. Our results indicate that the immunization with V. cholerae or ETEC OMVs induced a species-specific immune response, whereas the combination of both OMV species resulted in a high-titer, protective immune response against both pathogens. Interestingly, the immunization with V. cholerae OMVs alone resulted in a so far uncharacterized and cholera toxin B-subunit (CTB) independent protection mechanism against an ETEC colonization. Furthermore, we investigated the potential use of V. cholerae OMVs as delivery vehicles for the heterologously expression of the ETEC surface antigens, CFA/I, and FliC. Although we induced a detectable immune response against both heterologously expressed antigens, none of these approaches resulted in an improved protection compared to a simple combination of V. cholerae and ETEC OMVs. Finally, we expanded the current protection model from V. cholerae to ETEC by demonstrating that the inhibition of motility via anti-FliC antibodies represents a relevant protection mechanism of an OMV-based ETEC vaccine candidate in vivo.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Stefan Schild
- Institute of Molecular Biosciences, University of GrazGraz, Austria
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Wang X, Guan Q, Wang X, Teng D, Mao R, Yao J, Wang J. Paving the way to construct a new vaccine against Escherichia coli from its recombinant outer membrane protein C via a murine model. Process Biochem 2015. [DOI: 10.1016/j.procbio.2015.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Karlsson SL, Ax E, Nygren E, Källgård S, Blomquist M, Ekman A, Benktander J, Holmgren J, Lebens M. Development of stable Vibrio cholerae O1 Hikojima type vaccine strains co-expressing the Inaba and Ogawa lipopolysaccharide antigens. PLoS One 2014; 9:e108521. [PMID: 25397871 PMCID: PMC4232259 DOI: 10.1371/journal.pone.0108521] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 08/21/2014] [Indexed: 11/19/2022] Open
Abstract
We describe here the development of stable classical and El Tor V. cholerae O1 strains of the Hikojima serotype that co–express the Inaba and Ogawa antigens of O1 lipopolysaccharide (LPS). Mutation of the wbeT gene reduced LPS perosamine methylation and thereby gave only partial transformation into Ogawa LPS on the cell surface. The strains express approximately equal amounts of Inaba– and Ogawa–LPS antigens which are preserved after formalin–inactivation of the bacteria. Oral immunizations of both inbred and outbred mice with formalin–inactivated whole–cell vaccine preparations of these strains elicited strong intestinal IgA anti–LPS as well as serum vibriocidal antibody responses against both Inaba and Ogawa that were fully comparable to the responses induced by the licensed Dukoral vaccine. Passive protection studies in infant mice showed that immune sera raised against either of the novel Hikojima vaccine strains protected baby mice against infection with virulent strains of both serotypes. This study illustrates the power of using genetic manipulation to improve the properties of bacteria strains for use in killed whole–cell vaccines.
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Affiliation(s)
- Stefan L. Karlsson
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Elisabeth Ax
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Erik Nygren
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Susanne Källgård
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Margareta Blomquist
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Annelie Ekman
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - John Benktander
- Department of Medical Biochemistry and Cell Biology at Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
| | - Jan Holmgren
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
| | - Michael Lebens
- Department of Microbiology and Immunology at Institute of Biomedicine, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden
- * E-mail:
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Abstract
Over the past three decades, a powerful array of techniques has been developed for expressing heterologous proteins and saccharides on the surface of bacteria. Surface-engineered bacteria, in turn, have proven useful in a variety of settings, including high-throughput screening, biofuel production, and vaccinology. In this chapter, we provide a comprehensive review of methods for displaying polypeptides and sugars on the bacterial cell surface, and discuss the many innovative applications these methods have found to date. While already an important biotechnological tool, we believe bacterial surface display may be further improved through integration with emerging methodology in other fields, such as protein engineering and synthetic chemistry. Ultimately, we envision bacterial display becoming a multidisciplinary platform with the potential to transform basic and applied research in bacteriology, biotechnology, and biomedicine.
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Multiepitope fusion antigen induces broadly protective antibodies that prevent adherence of Escherichia coli strains expressing colonization factor antigen I (CFA/I), CFA/II, and CFA/IV. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 21:243-9. [PMID: 24351757 DOI: 10.1128/cvi.00652-13] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Diarrhea is the second leading cause of death in children younger than 5 years and continues to be a major threat to global health. Enterotoxigenic Escherichia coli (ETEC) strains are the most common bacteria causing diarrhea in developing countries. ETEC strains are able to attach to host small intestinal epithelial cells by using bacterial colonization factor antigen (CFA) adhesins. This attachment helps to initiate the diarrheal disease. Vaccines that induce antiadhesin immunity to block adherence of ETEC strains that express immunologically heterogeneous CFA adhesins are expected to protect against ETEC diarrhea. In this study, we created a CFA multiepitope fusion antigen (MEFA) carrying representative epitopes of CFA/I, CFA/II (CS1, CS2, and CS3), and CFA/IV (CS4, CS5, and CS6), examined its immunogenicity in mice, and assessed the potential of this MEFA as an antiadhesin vaccine against ETEC. Mice intraperitoneally immunized with this CFA MEFA exhibited no adverse effects and developed immune responses to CFA/I, CFA/II, and CFA/IV adhesins. Moreover, after incubation with serum of the immunized mice, ETEC or E. coli strains expressing CFA/I, CFA/II, or CFA/IV adhesins were significantly inhibited in adherence to Caco-2 cells. Our results indicated this CFA MEFA elicited antibodies that not only cross-reacted to CFA/I, CFA/II and CFA/IV adhesins but also broadly inhibited adherence of E. coli strains expressing these seven adhesins and suggested that this CFA MEFA could be a candidate to induce broad-spectrum antiadhesin protection against ETEC diarrhea. Additionally, this antigen construction approach (creating an MEFA) may be generally used in vaccine development against heterogenic pathogens.
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Croxen MA, Law RJ, Scholz R, Keeney KM, Wlodarska M, Finlay BB. Recent advances in understanding enteric pathogenic Escherichia coli. Clin Microbiol Rev 2013; 26:822-80. [PMID: 24092857 PMCID: PMC3811233 DOI: 10.1128/cmr.00022-13] [Citation(s) in RCA: 831] [Impact Index Per Article: 75.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Although Escherichia coli can be an innocuous resident of the gastrointestinal tract, it also has the pathogenic capacity to cause significant diarrheal and extraintestinal diseases. Pathogenic variants of E. coli (pathovars or pathotypes) cause much morbidity and mortality worldwide. Consequently, pathogenic E. coli is widely studied in humans, animals, food, and the environment. While there are many common features that these pathotypes employ to colonize the intestinal mucosa and cause disease, the course, onset, and complications vary significantly. Outbreaks are common in developed and developing countries, and they sometimes have fatal consequences. Many of these pathotypes are a major public health concern as they have low infectious doses and are transmitted through ubiquitous mediums, including food and water. The seriousness of pathogenic E. coli is exemplified by dedicated national and international surveillance programs that monitor and track outbreaks; unfortunately, this surveillance is often lacking in developing countries. While not all pathotypes carry the same public health profile, they all carry an enormous potential to cause disease and continue to present challenges to human health. This comprehensive review highlights recent advances in our understanding of the intestinal pathotypes of E. coli.
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Development and preclinical evaluation of safety and immunogenicity of an oral ETEC vaccine containing inactivated E. coli bacteria overexpressing colonization factors CFA/I, CS3, CS5 and CS6 combined with a hybrid LT/CT B subunit antigen, administered alone and together with dmLT adjuvant. Vaccine 2013; 31:2457-64. [PMID: 23541621 DOI: 10.1016/j.vaccine.2013.03.027] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 02/07/2013] [Accepted: 03/14/2013] [Indexed: 01/28/2023]
Abstract
A first-generation oral inactivated whole-cell enterotoxigenic Escherichia coli (ETEC) vaccine, comprising formalin-killed ETEC bacteria expressing different colonization factor (CF) antigens combined with cholera toxin B subunit (CTB), when tested in phase III studies did not significantly reduce overall (generally mild) ETEC diarrhea in travelers or children although it reduced more severe ETEC diarrhea in travelers by almost 80%. We have now developed a novel more immunogenic ETEC vaccine based on recombinant non-toxigenic E. coli strains engineered to express increased amounts of CF antigens, including CS6 as well as an ETEC-based B subunit protein (LCTBA), and the optional combination with a nontoxic double-mutant heat-labile toxin (LT) molecule (dmLT) as an adjuvant. Two test vaccines were prepared under GMP: (1) A prototype E. coli CFA/I-only formalin-killed whole-cell+LCTBA vaccine, and (2) A "complete" inactivated multivalent ETEC-CF (CFA/I, CS3, CS5 and CS6 antigens) whole-cell+LCTBA vaccine. These vaccines, when given intragastrically alone or together with dmLT in mice, were well tolerated and induced strong intestinal-mucosal IgA antibody responses as well as serum IgG and IgA responses to each of the vaccine CF antigens as well as to LT B subunit (LTB). Both mucosal and serum responses were further enhanced (adjuvanted) when the vaccines were co-administered with dmLT. We conclude that the new multivalent oral ETEC vaccine, both alone and especially in combination with the dmLT adjuvant, shows great promise for further testing in humans.
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Lundgren A, Leach S, Tobias J, Carlin N, Gustafsson B, Jertborn M, Bourgeois L, Walker R, Holmgren J, Svennerholm AM. Clinical trial to evaluate safety and immunogenicity of an oral inactivated enterotoxigenic Escherichia coli prototype vaccine containing CFA/I overexpressing bacteria and recombinantly produced LTB/CTB hybrid protein. Vaccine 2013; 31:1163-70. [DOI: 10.1016/j.vaccine.2012.12.063] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/18/2012] [Accepted: 12/26/2012] [Indexed: 11/30/2022]
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The adjuvant double mutant Escherichia coli heat labile toxin enhances IL-17A production in human T cells specific for bacterial vaccine antigens. PLoS One 2012; 7:e51718. [PMID: 23284753 PMCID: PMC3527457 DOI: 10.1371/journal.pone.0051718] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Accepted: 11/05/2012] [Indexed: 01/15/2023] Open
Abstract
The strong adjuvant activity and low enterotoxicity of the novel mucosal adjuvant double mutant Escherichia coli heat labile toxin, LT(R192G/L211A) or dmLT, demonstrated in mice, makes this molecule a promising adjuvant candidate. However, little is known about the mechanisms responsible for the adjuvant effect of dmLT or whether dmLT also has an adjuvant function in humans. We investigated the effect of dmLT on human T cell responses to different bacterial vaccine antigens: the mycobacterial purified protein derivative (PPD) antigen, tested in individuals previously vaccinated with Bacillus Calmette-Guérin, the LT binding subunit (LTB), evaluated in subjects immunised with oral inactivated whole cell vaccines against enterotoxigenic Escherichia coli, and Streptococcus pneumoniae whole cell vaccine antigens, tested in subjects naturally exposed to pneumococci. We found that dmLT enhanced the production of IL-17A by peripheral blood mononuclear cells in response to all antigens tested. dmLT had comparable effects on IL-17A responses to PPD as the single mutant LT(R192G) adjuvant, which has demonstrated clinical adjuvant activity in humans. Neutralisation of IL-1β and IL-23, but not IL-6, suppressed the IL-17A-enhancing effect of dmLT. Furthermore, CD4+ T cells produced higher levels of IL-17A when stimulated with monocytes pulsed with PPD and dmLT compared to PPD alone, supporting an important role of antigen presenting cells in enhancing IL-17A responses. dmLT also potentiated mitogen-induced IL-17A and IL-13 production. However, dmLT had variable influences on IFN-γ responses to the different stimuli tested. Our demonstration of a potent ability of dmLT to enhance human Th17 type T cell responses to bacterial vaccine antigens encourages further evaluation of the adjuvant function of dmLT in humans.
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Saxena M, Van TTH, Baird FJ, Coloe PJ, Smooker PM. Pre-existing immunity against vaccine vectors--friend or foe? MICROBIOLOGY-SGM 2012; 159:1-11. [PMID: 23175507 PMCID: PMC3542731 DOI: 10.1099/mic.0.049601-0] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Over the last century, the successful attenuation of multiple bacterial and viral pathogens has led to an effective, robust and safe form of vaccination. Recently, these vaccines have been evaluated as delivery vectors for heterologous antigens, as a means of simultaneous vaccination against two pathogens. The general consensus from published studies is that these vaccine vectors have the potential to be both safe and efficacious. However, some of the commonly employed vectors, for example Salmonella and adenovirus, often have pre-existing immune responses in the host and this has the potential to modify the subsequent immune response to a vectored antigen. This review examines the literature on this topic, and concludes that for bacterial vectors there can in fact, in some cases, be an enhancement in immunogenicity, typically humoral, while for viral vectors pre-existing immunity is a hindrance for subsequent induction of cell-mediated responses.
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Affiliation(s)
- Manvendra Saxena
- Ludwig Institute for Cancer Research, Heidelberg, Victoria, Australia
| | - Thi Thu Hao Van
- School of Applied Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Fiona J Baird
- Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Queensland, Australia
| | - Peter J Coloe
- School of Applied Sciences, RMIT University, Bundoora, Victoria, Australia
| | - Peter M Smooker
- School of Applied Sciences, RMIT University, Bundoora, Victoria, Australia
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Svennerholm AM, Lundgren A. Recent progress toward an enterotoxigenic Escherichia coli vaccine. Expert Rev Vaccines 2012; 11:495-507. [PMID: 22551034 DOI: 10.1586/erv.12.12] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Enterotoxigenic Escherichia coli(ETEC) is the most common cause of bacterial diarrhea in children in Africa, Asia and Latin America and in travelers to these regions. Despite this, no effective vaccine for ETEC is available. ETEC causes disease by colonizing the small intestine with colonization factors, most of which are fimbriae, and production of heat-labile and/or heat-stable enterotoxins. Antibodies against heat-labile enterotoxin and the colonization factors have been shown to be protective, and local immunity in the gut seems to be of prime importance for protection. Hence, several inactivated and live candidate ETEC vaccines consisting of toxin antigens, alone or together with colonization factors, have been evaluated in clinical trials. In this review, the authors describe ETEC vaccine development in progress and the rationale for constructing different types of vaccines. They also discuss possibilities of enhancing immune responses to candidate ETEC vaccines, particularly in children.
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Affiliation(s)
- Ann-Mari Svennerholm
- Gothenburg University Vaccine Research Institute and Department of Microbiology and Immunology, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Sweden.
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Cao L, Suo Z, Lim T, Jun S, Deliorman M, Riccardi C, Kellerman L, Avci R, Yang X. Role of overexpressed CFA/I fimbriae in bacterial swimming. Phys Biol 2012; 9:036005. [PMID: 22562964 DOI: 10.1088/1478-3975/9/3/036005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Enterotoxigenic Escherichia coli CFA/I is a protective antigen and has been overexpressed in bacterial vectors, such as Salmonella Typhimurium H683, to generate vaccines. Effects that overexpressed CFA/I may engender on the bacterial host remain largely unexplored. To investigate, we constructed a high CFA/I expression strain, H683-pC2, and compared it to a low CFA/I expression strain, H683-pC, and to a non-CFA/I expression strain, H683-pY. The results showed that H683-pC2 was less able to migrate into semisolid agar (0.35%) than either H683-pC or H683-pY. Bacteria that migrated showed motility halo sizes of H683-pC2 < H683-pC < H683-pY. In the liquid culture media, H683-pC2 cells precipitated to the bottom of the tube, while those of H683-pY did not. In situ imaging revealed that H683-pC2 bacilli tended to auto-agglutinate within the semisolid agar, while H683-pY bacilli did not. When the cfaBE fimbrial fiber encoding genes were deleted from pC2, the new plasmid, pC2(-), significantly recovered bacterial swimming capability. Our study highlights the negative impact of overexpressed CFA/I fimbriae on bacterial swimming motility.
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Affiliation(s)
- Ling Cao
- Immunology & Infectious Diseases, Montana State University, Bozeman, MT 59717-3610, USA
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Tobias J, Svennerholm AM. Strategies to overexpress enterotoxigenic Escherichia coli (ETEC) colonization factors for the construction of oral whole-cell inactivated ETEC vaccine candidates. Appl Microbiol Biotechnol 2012; 93:2291-300. [DOI: 10.1007/s00253-012-3930-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 01/27/2012] [Accepted: 01/28/2012] [Indexed: 11/25/2022]
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Abstract
The meeting was held in the beautiful city of Ghent, Belgium, to bring together basic scientists and clinicians working on Escherichia coli and the mucosal immune system; in particular focusing on cellular interactions, immune modulation and vaccination strategies in humans and animals. The aim was to exchange knowledge on the pathogenicity of different types of E. coli and recent advances in the area of mucosal immunity. The meeting was timely given the recent outbreak in northern Germany of an emergent Shiga toxigenic E. coli strain that was associated with the deaths of over 45 people and caused hemolytic uremic syndrome in nearly 800 individuals according to the European Centre for Disease Prevention and Control.
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Affiliation(s)
- Arvind Mahajan
- Division of Immunity and Infection, Roslin Institute, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
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Tobias J, Svennerholm AM, Carlin NIA, Lebens M, Holmgren J. Construction of a non-toxigenic Escherichia coli oral vaccine strain expressing large amounts of CS6 and inducing strong intestinal and serum anti-CS6 antibody responses in mice. Vaccine 2011; 29:8863-9. [PMID: 21983363 DOI: 10.1016/j.vaccine.2011.09.096] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 09/12/2011] [Accepted: 09/25/2011] [Indexed: 10/16/2022]
Abstract
Coli surface antigen 6 (CS6) is one of the most prevalent non-fimbrial colonization factors (CFs) of enterotoxigenic Escherichia coli (ETEC) bacteria, which are the most common cause of diarrhea among infants and children in developing countries. Since immune protection against ETEC is mainly mediated by locally produced IgA antibodies in the gut, much effort is focused on the development of an oral CF-based vaccine. Previous work has described the preparation of candidate E. coli vaccine strains expressing immunogenic amounts of fimbrial CF antigens such as CFA/I and CS2, which are retained after formalin treatment. However, attempts to generate E. coli expressing immunogenic amounts of CS6 and to preserve the immunological activity of the CS6 protein in a killed whole-cell vaccine have failed until now. Here we describe the construction of a recombinant non-toxigenic E. coli strain, with thyA as a non-antibiotic-based selection, which expresses large amounts of CS6 antigen on the bacterial surface, and show that phenol inactivation of the bacteria does not destroy the CS6 antigen properties. Oral immunization of mice with such phenol-killed CS6 over-expressing E. coli bacteria induced strong fecal and intestinal IgA and serum IgG+IgM antibody responses to CS6 that exceeded the responses induced by an ETEC reference strain naturally expressing CS6 and previously used as a vaccine strain. Our data indicate that the described phenol-inactivated non-toxigenic and CS6 over-expressing E. coli strain may be a useful component in an oral ETEC vaccine.
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Affiliation(s)
- Joshua Tobias
- University of Gothenburg Vaccine Research Institute, and WHO Collaborating Center for Research on Enterotoxigenic Escherichia coli, Department of Microbiology and Immunology, The Sahlgrenska Academy of University of Gothenburg, S-40530 Gothenburg, Sweden.
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