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Talaat KR, Porter CK, Chakraborty S, Feijoo BL, Brubaker J, Adjoodani BM, DeNearing B, Prouty MG, Poole ST, Bourgeois AL, Billingsley M, Sack DA, Eder-Lingelbach S, Taucher C. Validation of a Human Challenge Model Using an LT-Expressing Enterotoxigenic E. coli Strain (LSN03-016011) and Characterization of Potential Amelioration of Disease by an Investigational Oral Vaccine Candidate (VLA1701). Microorganisms 2024; 12:727. [PMID: 38674674 DOI: 10.3390/microorganisms12040727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/22/2024] [Accepted: 03/23/2024] [Indexed: 04/28/2024] Open
Abstract
Controlled human infection models are important tools for the evaluation of vaccines against diseases where an appropriate correlate of protection has not been identified. Enterotoxigenic Escherichia coli (ETEC) strain LSN03-016011/A (LSN03) is an LT enterotoxin and CS17-expressing ETEC strain useful for evaluating vaccine candidates targeting LT-expressing strains. We sought to confirm the ability of the LSN03 strain to induce moderate-to-severe diarrhea in a healthy American adult population, as well as the impact of immunization with an investigational cholera/ETEC vaccine (VLA-1701) on disease outcomes. A randomized, double-blinded pilot study was conducted in which participants received two doses of VLA1701 or placebo orally, one week apart; eight days after the second vaccination, 30 participants (15 vaccinees and 15 placebo recipients) were challenged with approximately 5 × 109 colony-forming units of LSN03. The vaccine was well tolerated, with no significant adverse events. The vaccine also induced serum IgA and IgG responses to LT. After challenge, 11 of the placebo recipients (73.3%; 95%CI: 48.0-89.1) and 7 of the VLA1701 recipients (46.7%; 95%CI: 24.8-68.8) had moderate-to-severe diarrhea (p = 0.26), while 14 placebo recipients (93%) and 8 vaccine recipients (53.3%) experienced diarrhea of any severity, resulting in a protective efficacy of 42.9% (p = 0.035). In addition, the vaccine also appeared to provide protection against more severe diarrhea (p = 0.054). Vaccinees also tended to shed lower levels of the LSN03 challenge strain compared to placebo recipients (p = 0.056). In addition, the disease severity score was lower for the vaccinees than for the placebo recipients (p = 0.046). In summary, the LSN03 ETEC challenge strain induced moderate-to-severe diarrhea in 73.3% of placebo recipients. VLA1701 vaccination ameliorated disease severity, as observed by several parameters, including the percentage of participants experiencing diarrhea, as well as stool frequency and ETEC severity scores. These data highlight the potential value of LSN03 as a suitable ETEC challenge strain to evaluate LT-based vaccine targets (NCT03576183).
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Affiliation(s)
- Kawsar R Talaat
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Chad K Porter
- Naval Medical Research Command, Silver Spring, MD 20910, USA
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Brittany L Feijoo
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Jessica Brubaker
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Brittany M Adjoodani
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Barbara DeNearing
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | | | - Steven T Poole
- Naval Medical Research Command, Silver Spring, MD 20910, USA
| | - A Louis Bourgeois
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Madison Billingsley
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Banerjee S, Barry EM, Baqar S, Louis Bourgeois A, Campo JJ, Choy RKM, Chakraborty S, Clifford A, Deal C, Estrada M, Fleckenstein J, Hasso-Agopsowicz M, Hausdorff W, Khalil I, Maier N, Mubanga C, Platts-Mills JA, Porter C, Qadri F, Simuyandi M, Walker R, White JA. The 2022 Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference: Summary of abstract-based presentations. Vaccine 2024; 42:1454-1460. [PMID: 38030421 PMCID: PMC10953701 DOI: 10.1016/j.vaccine.2023.11.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 12/01/2023]
Abstract
The global nonprofit organization PATH hosted the third Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference in Washington, DC, on November 29 to December 1, 2022. With a combination of plenary sessions and posters, keynote presentations, and breakout workshops, the 2022 VASE Conference featured key updates on research related to the development of vaccines against neglected diarrheal pathogens including Shigella, enterotoxigenic Escherichia coli (ETEC), Campylobacter, and Salmonella. The presentations and discussions highlighted the significant impact of these diarrheal pathogens, particularly on the health of infants and young children in low- and middle-income countries, reflecting the urgent need for the development and licensure of new enteric vaccines. Oral and poster presentations at the VASE Conference explored a range of topics, including: the global burden and clinical presentation of disease, epidemiology, and the impact of interventions; the assessment of the value of vaccines against enteric pathogens; preclinical evaluations of vaccine candidates and models of enteric diseases; vaccine candidates in clinical trials and human challenge models; host parameters and genomics that predict responses to infection and disease; the application of new omics technologies for characterization of emerging pathogens and host responses; novel adjuvants, vaccine delivery platforms, and immunization strategies; and strategies for combination/co-administered vaccines. The conference agenda also featured ten breakout workshop sessions on topics of importance to the enteric vaccine field, which are summarized separately. This article reviews key points and highlighted research presented in each of the plenary conference sessions and poster presentations at the 2022 VASE Conference.
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Affiliation(s)
| | - Eileen M Barry
- University of Maryland School of Medicine, United States
| | | | | | | | | | | | | | | | | | | | | | - William Hausdorff
- PATH, United States; Faculty of Medicine, Université Libre de Bruxelles, Belgium
| | | | | | | | - James A Platts-Mills
- Division of Infectious Diseases and International Health, University of Virginia, United States
| | - Chad Porter
- Naval Medical Research Command, United States
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Baqar S, Bonavia A, Louis Bourgeois A, Campo JJ, Clifford A, Hanevik K, Hasso-Agopsowicz M, Hausdorff W, Kaminski R, MacLennan CA, Mantis N, Martin LB, Omore R, Pasetti M, Pavlinac P, Phalipon A, Poly F, Porter C, Ramasamy MN, Rogawski McQuade ET, Sztein MB, Walker R. The 2022 Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference: Summary of breakout workshops. Vaccine 2024; 42:1445-1453. [PMID: 38036392 PMCID: PMC10953702 DOI: 10.1016/j.vaccine.2023.11.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/25/2023] [Accepted: 11/21/2023] [Indexed: 12/02/2023]
Abstract
The global public health nonprofit organization PATH hosted the third Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference in Washington, DC, from November 29 to December 1, 2022. This international gathering focused on cutting-edge research related to the development of vaccines against neglected diarrheal pathogens including Shigella, enterotoxigenic Escherichia coli (ETEC), Campylobacter, and non-typhoidal Salmonella. In addition to the conference's plenary content, the agenda featured ten breakout workshops on topics of importance to the enteric vaccine field. This unique aspect of VASE Conferences allows focused groups of attendees to engage in in-depth discussions on subjects of interest to the enteric vaccine development community. In 2022, the workshops covered a range of topics. Two focused on the public health value of enteric vaccines, with one examining how to translate evidence into policy and the other on the value proposition of potential combination vaccines against bacterial enteric pathogens. Two more workshops explored new tools for the development and evaluation of vaccines, with the first on integrating antigen/antibody technologies for mucosal vaccine and immunoprophylactic development, and the second on adjuvants specifically for Shigella vaccines for children in low- and middle-income countries. Another pair of workshops covered the status of vaccines against two emerging enteric pathogens, Campylobacter and invasive non-typhoidal Salmonella. The remaining four workshops examined the assessment of vaccine impact on acute and long-term morbidity. These included discussions on the nature and severity of intestinal inflammation; cellular immunity and immunological memory in ETEC and Shigella infections; clinical and microbiologic endpoints for Shigella vaccine efficacy studies in children; and intricacies of protective immunity to enteric pathogens. This article provides a brief summary of the presentations and discussions at each workshop in order to share these sessions with the broader enteric vaccine field.
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Affiliation(s)
| | - Aurelio Bonavia
- Bill & Melinda Gates Medical Research Institute, United States
| | | | | | | | - Kurt Hanevik
- University of Bergen, Norway; Norwegian National Advisory Unit for Tropical Infectious Diseases, Medical Department, Haukeland University Hospital, Norway
| | | | - William Hausdorff
- PATH, United States; Faculty of Medicine, Université Libre de Bruxelles, Belgium
| | | | - Calman A MacLennan
- Enteric and Diarrheal Diseases, Bill & Melinda Gates Foundation, United Kingdom; The Jenner Institute, United Kingdom
| | - Nicholas Mantis
- Wadsworth Center, New York State Department of Health, United States
| | | | - Richard Omore
- Kenya Medical Research Institute Center for Global Health Research, Kenya
| | | | | | | | | | - Chad Porter
- Naval Medical Research Command, United States
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Hausdorff WP, Anderson JD, Bourgeois AL, Clifford A, Fleming JA, Muhib F, Pecenka C, Puett C, Riddle MS, Scheele S, Bagamian KH. Reassessing potential economic value and health impact of effective Shigella vaccines. Bull World Health Organ 2024; 102:65-74. [PMID: 38164339 PMCID: PMC10753284 DOI: 10.2471/blt.23.290163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 08/22/2023] [Accepted: 10/20/2023] [Indexed: 01/03/2024] Open
Abstract
The gram-negative bacterium Shigella is a leading cause of diarrheal morbidity and mortality in children in low- and middle-income countries. Several promising vaccine candidates are in late stages of clinical development against this increasingly antibiotic-resistant pathogen. However, considering the increasingly crowded and costly paediatric immunization schedule, and likely advent of other important new vaccines, it is unclear whether introduction of a Shigella vaccine would represent a high priority for international agencies or health ministries in low- and middle-income countries. To determine whether there is a compelling public health value proposition for a Shigella vaccine, we used the World Health Organization's Full Value of Vaccine Assessment analytic framework and formulated five broad scientific, policy, economic and commercial-related propositions regarding the development of a Shigella vaccine. We also explored the current regulatory, clinical, policy and commercial challenges to a Shigella-containing combination vaccine development and adoption. Through a series of literature reviews, expert consultations, social science field studies and model-based analyses, we addressed each of these propositions. As described in a series of separate publications that are synthesized here, we concluded that the economic and public health value of a Shigella vaccine may be greater than previously recognized, particularly if it is found to also be effective against less severe forms of diarrheal disease and childhood stunting. The decision by pharmaceutical companies to develop a standalone vaccine or a multipathogen combination will be a key factor in determining its relative prioritization by various stakeholders in low- and middle-income countries.
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Affiliation(s)
- William P Hausdorff
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Avenue NW, Washington, D.C.20001, United States of America (USA)
| | | | - A Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Avenue NW, Washington, D.C.20001, United States of America (USA)
| | - Allison Clifford
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Avenue NW, Washington, D.C.20001, United States of America (USA)
| | | | - Farzana Muhib
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Avenue NW, Washington, D.C.20001, United States of America (USA)
| | | | - Chloe Puett
- Stony Brook University, Stony Brook, New York, USA
| | | | - Suzanne Scheele
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Avenue NW, Washington, D.C.20001, United States of America (USA)
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5
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Khalil I, Anderson JD, Bagamian KH, Baqar S, Giersing B, Hausdorff WP, Marshall C, Porter CK, Walker RI, Bourgeois AL. Vaccine value profile for enterotoxigenic Escherichia coli (ETEC). Vaccine 2023; 41 Suppl 2:S95-S113. [PMID: 37951695 DOI: 10.1016/j.vaccine.2023.02.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/28/2022] [Accepted: 02/05/2023] [Indexed: 11/14/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is one of the leading bacterial causes of diarrhoea, especially among children in low-resource settings, and travellers and military personnel from high-income countries. WHO's primary strategic goal for ETEC vaccine development is to develop a safe, effective, and affordable ETEC vaccine that reduces mortality and morbidity due to moderate-to-severe diarrhoeal disease in infants and children under 5 years of age in LMICs, as well as the long-term negative health impact on infant physical and cognitive development resulting from infection with this enteric pathogen. An effective ETEC vaccine will also likely reduce the need for antibiotic treatment and help limit the further emergence of antimicrobial resistance bacterial pathogens. The lead ETEC vaccine candidate, ETVAX, has shown field efficacy in travellers and has moved into field efficacy testing in LMIC infants and children. A Phase 3 efficacy study in LMIC infants is projected to start in 2024 and plans for a Phase 3 trial in travellers are under discussion with the U.S. FDA. Licensing for both travel and LMIC indications is projected to be feasible in the next 5-8 years. Given increasing recognition of its negative impact on child health and development in LMICs and predominance as the leading etiology of travellers' diarrhoea (TD), a standalone vaccine for ETEC is more cost-effective than vaccines targeting other TD pathogens, and a viable commercial market also exists. In contrast, combination of an ETEC vaccine with other vaccines for childhood pathogens in LMICs would maximize protection in a more cost-effective manner than a series of stand-alone vaccines. This 'Vaccine Value Profile' (VVP) for ETEC is intended to provide a high-level, holistic assessment of available data to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations. All contributors have extensive expertise on various elements of the ETEC VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.
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Affiliation(s)
- Ibrahim Khalil
- Department of Global Health, University of Washington, Seattle, WA 98195, USA.
| | - John D Anderson
- Bagamian Scientific Consulting, LLC, Gainesville, FL 32601, USA; Office of Health Affairs, West Virginia University, Morgantown, WV 26505, USA
| | - Karoun H Bagamian
- Bagamian Scientific Consulting, LLC, Gainesville, FL 32601, USA; Department of Environmental and Global Health, University of Florida, Gainesville, FL 32603, USA
| | - Shahida Baqar
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Birgitte Giersing
- Department of Immunization, Vaccines and Biologicals (IVB), World Health Organization (WHO), Geneva, Switzerland
| | - William P Hausdorff
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001 USA; Faculty of Medicine, Université Libre de Bruxelles, Brussels 1070, Belgium
| | - Caroline Marshall
- Department of Immunization, Vaccines and Biologicals (IVB), World Health Organization (WHO), Geneva, Switzerland
| | - Chad K Porter
- Directorate for DoD Infectious Diseases Research, Naval Medical Research Command, Silver Spring, MD 20190, USA
| | - Richard I Walker
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001 USA
| | - A Louis Bourgeois
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001 USA
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Hausdorff WP, Anderson JD, Bagamian KH, Bourgeois AL, Mills M, Sawe F, Scheele S, Talaat K, Giersing BK. Vaccine value profile for Shigella. Vaccine 2023; 41 Suppl 2:S76-S94. [PMID: 37827969 DOI: 10.1016/j.vaccine.2022.12.037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 10/14/2022] [Accepted: 12/16/2022] [Indexed: 10/14/2023]
Abstract
Shigella is the leading bacterial cause of diarrhoea and the second leading cause of diarrhoeal mortality among all ages. It also exhibits increasing levels of antibiotic resistance. The greatest burden is among children under five in low- and middle-income countries (LMICs). As such, a priority strategic goal of the World Health Organization (WHO) is the development of a safe, effective and affordable vaccine to reduce morbidity and mortality from Shigella-attributable dysentery and diarrhea, including long term outcomes associated with chronic inflammation and growth faltering, in children under 5 years of age in LMICs. In addition, a safe and effective Shigella vaccine is of potential interest to travellers and military both to prevent acute disease and rarer, long-term sequelae. An effective Shigella vaccine is also anticipated to reduce antibiotic use and thereby help diminish further emergence of enteric pathogens resistant to antimicrobials. The most advanced vaccine candidates are multivalent, parenteral formulations in Phase 2 and Phase 3 clinical studies. They rely on O-antigen-polysaccharide protein conjugate technologies or, alternatively, outer membrane vesicles expressing penta-acylated lipopolysaccharide that has been detoxified. Other parenteral and oral formulations, many delivering a broader array of Shigella antigens, are at earlier stages of clinical development. These formulations are being assessed in alignment with the WHO Preferred Product Characteristics, which call for a 1 to 2 dose primary immunization series given during the first 12 months of life, ideally starting at 6 months of age. This 'Vaccine Value Profile' (VVP) for Shigella is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, government agencies and multi-lateral organizations. All contributors have extensive expertise on various elements of the Shigella VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.
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Affiliation(s)
- William P Hausdorff
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Ave NW, Washington, DC 20001, USA; Faculty of Medicine, Université de Bruxelles, Brussels 1070, Belgium.
| | - John D Anderson
- Office of Health Affairs, West Virginia University, Morgantown, WV 26505, USA; Bagamian Scientific Consulting, LLC, Gainesville, FL 32601, USA
| | - Karoun H Bagamian
- Bagamian Scientific Consulting, LLC, Gainesville, FL 32601, USA; Department of Environmental and Global Health, University of Florida, Gainesville, FL 32603, USA
| | - A Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Ave NW, Washington, DC 20001, USA
| | - Melody Mills
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 USA
| | - Frederick Sawe
- Kenya Medical Research Institute/U.S. Army Medical Research Directorate-Africa/Kenya-Henry Jackson Foundation MRI, Kericho, Kenya
| | - Suzanne Scheele
- Center for Vaccine Innovation and Access, PATH, 455 Massachusetts Ave NW, Washington, DC 20001, USA
| | - Kawsar Talaat
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Birgitte K Giersing
- Department of Immunization, Vaccines and Biologicals (IVB), World Health Organization (WHO), Geneva, Switzerland
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Maier N, Grahek SL, Halpern J, Restrepo S, Troncoso F, Shimko J, Torres O, Belkind-Gerson J, Sack DA, Svennerholm AM, Gustafsson B, Sjöstrand B, Carlin N, Bourgeois AL, Porter CK. Efficacy of an Enterotoxigenic Escherichia coli (ETEC) Vaccine on the Incidence and Severity of Traveler's Diarrhea (TD): Evaluation of Alternative Endpoints and a TD Severity Score. Microorganisms 2023; 11:2414. [PMID: 37894071 PMCID: PMC10609384 DOI: 10.3390/microorganisms11102414] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Revised: 09/15/2023] [Accepted: 09/20/2023] [Indexed: 10/29/2023] Open
Abstract
The efficacy of an Oral Whole Cell ETEC Vaccine (OEV) against Travelers' Diarrhea (TD) was reexamined using novel outcome and immunologic measures. More specifically, a recently developed disease severity score and alternative clinical endpoints were evaluated as part of an initial validation effort to access the efficacy of a vaccine intervention for the first time in travelers to an ETEC endemic area. A randomized, double-blind, placebo-controlled trial followed travelers to Guatemala or Mexico up to 28 days after arrival in the country following vaccination (two doses two weeks apart) with an ETEC vaccine. Fecal samples were collected upon arrival, departure, and during TD for pathogen identification. Serum was collected in a subset of subjects to determine IgA cholera toxin B subunit (CTB) antibody titers upon their arrival in the country. The ETEC vaccine's efficacy, utilizing a TD severity score and other alternative endpoints, including the relationship between antibody levels and TD risk, was assessed and compared to the per-protocol primary efficacy endpoint. A total of 1435 subjects completed 7-28 days of follow-up and had available data. Vaccine efficacy was higher against more severe (≥5 unformed stools/24 h) ETEC-attributable TD and when accounting for immunologic take (PE ≥ 50%; p < 0.05). The vaccine protected against less severe (3 and 4 unformed stools/24 h) ETEC-attributable TD when accounting for symptom severity or change in activity (PE = 76.3%, p = 0.01). Immunologic take of the vaccine was associated with a reduced risk of infection with ETEC and other enteric pathogens, and with lower TD severity. Clear efficacy was observed among vaccinees with a TD score of ≥4 or ≥5, regardless of immunologic take (PE = 72.0% and 79.0%, respectively, p ≤ 0.03). The vaccine reduced the incidence and severity of ETEC, and this warrants accelerated evaluation of the improved formulation (designated ETVAX), currently undergoing advanced field testing. Subjects with serum IgA titers to CTB had a lower risk of infection with ETEC and Campylobacter jejuni/coli. Furthermore, the TD severity score provided a more robust descriptor of disease severity and should be included as an endpoint in future studies.
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Affiliation(s)
| | - Shannon L. Grahek
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; (S.L.G.); (J.H.); (S.R.); (F.T.); (J.S.); (D.A.S.)
| | - Jane Halpern
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; (S.L.G.); (J.H.); (S.R.); (F.T.); (J.S.); (D.A.S.)
| | - Suzanne Restrepo
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; (S.L.G.); (J.H.); (S.R.); (F.T.); (J.S.); (D.A.S.)
| | - Felipe Troncoso
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; (S.L.G.); (J.H.); (S.R.); (F.T.); (J.S.); (D.A.S.)
| | - Janet Shimko
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; (S.L.G.); (J.H.); (S.R.); (F.T.); (J.S.); (D.A.S.)
| | - Olga Torres
- Laboratorio Diagnostico Molecular, Guatemala City 01009, Guatemala;
| | | | - David A. Sack
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA; (S.L.G.); (J.H.); (S.R.); (F.T.); (J.S.); (D.A.S.)
| | - Ann-Mari Svennerholm
- Department of Microbiology and Immunology, University of Gothenburg, 405 30 Gothenburg, Sweden;
| | - Björn Gustafsson
- Scandinavian Biopharma Holding AB, 171 48 Stockholm, Sweden (B.S.); (N.C.)
| | - Björn Sjöstrand
- Scandinavian Biopharma Holding AB, 171 48 Stockholm, Sweden (B.S.); (N.C.)
| | - Nils Carlin
- Scandinavian Biopharma Holding AB, 171 48 Stockholm, Sweden (B.S.); (N.C.)
| | | | - Chad K. Porter
- Naval Medical Research Command, Silver Spring, MD 20910, USA;
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Riddle MS, Louis Bourgeois A, Clifford A, Jeon S, Giersing BK, Jit M, Tufet Bayona M, Ovitt J, Hausdorff WP. Challenges and opportunities in developing a Shigella-containing combination vaccine for children in low- and middle-income countries: Report of an expert convening. Vaccine 2023; 41:2634-2644. [PMID: 36932030 DOI: 10.1016/j.vaccine.2023.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 02/28/2023] [Accepted: 03/02/2023] [Indexed: 03/17/2023]
Abstract
The gram-negative bacterium Shigella is an enteric pathogen responsible for significant morbidity and mortality due primarily to severe diarrhea and dysentery, mainly among children younger than five years of age living in low- and middle-income countries (LMICs). Long considered a priority target for vaccine development, recent scientific advances have led to a number of promising Shigella vaccine candidates now entering advanced stages of clinical testing. Yet, there is no guarantee that even a highly efficacious Shigella vaccine will be recommended, prioritized, purchased, and widely adopted-especially if it requires additional doses in the immunization schedule and/or visits within the immunization program. This uncertainty is due to a variety of factors, including continuing declines in Shigella-specific and overall diarrheal disease mortality rates, the increasing complexity and cost of infant immunization programs in LMICs, and the recent availability of other high-priority vaccines. Since combining a Shigella vaccine with an existing infant vaccine would conceivably increase its attractiveness, there is a need to systematically consider the challenges determining the public health value, clinical development, manufacturing, licensure, policy recommendations, and financing for a Shigella-containing combination vaccine. The international non-governmental health organization PATH convened an independent panel of 34 subject matter experts across academic, industry, philanthropic, and global health sectors to discuss hypothetical combinations of a notional parenteral Shigella vaccine with three existing vaccines in order to begin exploring the challenges associated with their development. The resulting insights and recommendations from this meeting contribute to PATH's broader effort to evaluate the public health value of potential Shigella vaccines. They may also help guide future combination vaccine development efforts more broadly.
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Affiliation(s)
- Mark S Riddle
- University of Nevada, Reno School of Medicine, Reno, NV 89557, USA.
| | - A Louis Bourgeois
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001, USA
| | - Allison Clifford
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001, USA
| | - Suhi Jeon
- EuBiologics Co., Ltd. 8F, Seongdo Building, 207, Dosan-daero, Sinsa-dong, Gangnam-gu, Seoul, Republic of Korea
| | - Birgitte K Giersing
- World Health Organization, Immunization, Vaccines and Biologicals Department, 1211 Geneva, Switzerland
| | - Mark Jit
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Marta Tufet Bayona
- Gavi, The Vaccine Alliance, Chemin du Pommier 40, 1218 Le Grand-Saconnex, Geneva, Switzerland
| | - Jared Ovitt
- University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - William P Hausdorff
- PATH, Center for Vaccine Innovation and Access, 455 Massachusetts Ave NW, Washington, DC 20001, USA; Université Libre de Bruxelles, Faculty of Medicine, Brussels, Belgium
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Abstract
Oral immunization is an effective strategy for inducing protective immunity against mucosal enteric pathogens. Although live-attenuated as well as subunit approaches have been explored for vaccination against enteric pathogens, inactivated whole bacterial cells may also be effective in introducing protective immunity. Successfully accomplishing this goal with inactivated whole bacterial cells will require that a complex antigenic repertoire be presented in controlled immunogenic amounts, in a safe and relatively simple and self-contained delivery format. The benefit from immunization with whole cell vaccines can be further enhanced through genetic engineering to over-express selected antigens and also by the use of mucosal adjuvants to direct a more robust immunologic response. These steps are being taken for the development of ETVAX, the most clinically advanced vaccine candidate against the major enteric pathogen, enterotoxigenic Escherichia coli (ETEC) with significant positive impact.
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10
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Abstract
The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.
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Affiliation(s)
- Robert K. M. Choy
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | - A. Louis Bourgeois
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | | | - Richard I. Walker
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | | | - Jorge Flores
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
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11
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Clarkson KA, Porter CK, Talaat KR, Kapulu MC, Chen WH, Frenck RW, Bourgeois AL, Kaminski RW, Martin LB. Shigella-Controlled Human Infection Models: Current and Future Perspectives. Curr Top Microbiol Immunol 2022. [PMID: 35616717 DOI: 10.1007/82_2021_248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Shigella-controlled human infection models (CHIMs) are an invaluable tool utilized by the vaccine community to combat one of the leading global causes of infectious diarrhea, which affects infants, children and adults regardless of socioeconomic status. The impact of shigellosis disproportionately affects children in low- and middle-income countries (LMICs) resulting in cognitive and physical stunting, perpetuating a cycle that must be halted. Shigella-CHIMs not only facilitate the early evaluation of enteric countermeasures and up-selection of the most promising products but also provide insight into mechanisms of infection and immunity that are not possible utilizing animal models or in vitro systems. The greater understanding of shigellosis obtained in CHIMs builds and empowers the development of new generation solutions to global health issues which are unattainable in the conventional laboratory and clinical settings. Therefore, refining, mining and expansion of safe and reproducible infection models hold the potential to create effective means to end diarrheal disease and associated co-morbidities associated with Shigella infection.
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Affiliation(s)
- Kristen A Clarkson
- Department of Diarrheal Disease Research, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Chad K Porter
- Enteric Disease Department, Naval Medical Research Center, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Kawsar R Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway Street Hampton House, Baltimore, MD, 21205, USA
| | - Melissa C Kapulu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi County Hospital, Off Bofa Road, Kilifi, 80108, Kenya
| | - Wilbur H Chen
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD, 21201, USA
| | - Robert W Frenck
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - A Louis Bourgeois
- PATH Center for Vaccine Innovation and Access, 455 Massachusetts Avenue NW, Washington, DC, 20001, USA
| | - Robert W Kaminski
- Department of Diarrheal Disease Research, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD, 20910, USA
| | - Laura B Martin
- GSK Vaccines Institute for Global Health, Via Fiorentina 1, 53100, Siena, Italy.
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12
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Svennerholm AM, Qadri F, Lundgren A, Kaim J, Rahman Bhuiyan T, Akhtar M, Maier N, Louis Bourgeois A, Walker RI. Induction of mucosal and systemic immune responses against the common O78 antigen of an oral inactivated ETEC vaccine in Bangladeshi children and infants. Vaccine 2021; 40:380-389. [PMID: 34772542 DOI: 10.1016/j.vaccine.2021.10.056] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 10/21/2021] [Accepted: 10/25/2021] [Indexed: 10/19/2022]
Abstract
We tested an oral enterotoxigenic Escherichia coli (ETEC) vaccine, ETVAX, consisting of inactivated E. coli overexpressing the most prevalent ETEC colonization factors (CFs) and a toxoid (LCTBA), in Bangladeshi children for capacity to induce mucosal and plasma immune responses against O78 lipopolysaccharide (LPS) expressed on the vaccine strains. The vaccine was given ± double-mutant heat-labile toxin (dmLT) adjuvant. We evaluated the impact of dmLT on anti-O78 LPS immune responses and whether such responses can predict responses against the CFs as a marker for vaccine "take". Two fractionated doses of ETVAX ± different amounts of dmLT were administered biweekly to groups of children 24-59 (n = 125), 12-23 (n = 97) and 6-11 (n = 158) months of age. Immune responses were evaluated in antibody in lymphocyte supernatants (ALS), fecal extracts and plasma. ALS IgA responses against O78 LPS were induced in 44-49% of the children aged 12-59 months. The magnitudes of the ALS responses were significantly higher in children receiving a half-dose (5 × 1010 bacteria) of ETVAX ± dmLT than in placebo recipients. <10% of the vaccinees aged 6-11 months mounted ALS responses against O78 LPS. However, 49% of the infants developed fecal secretory IgA responses which were significantly more frequent in those receiving a quarter-dose (2.5 × 1010 bacteria) of vaccine + dmLT (62%) compared to a quarter-dose alone (36%). Plasma IgA antibody responses were induced in 80% of older children and 36% of infants. The frequencies of O78 LPS responses in plasma and feces were comparable or higher than against the vaccine CFs in infants. Our findings show that ETVAX induced mucosal and systemic immune responses against O78 LPS in all age groups and that dmLT improved intestinal immune responses among infants. These observations may have implications for more successful use of other oral vaccines based on O antigens in children.
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Affiliation(s)
- Ann-Mari Svennerholm
- Dept. of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Sweden.
| | - Firdausi Qadri
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Anna Lundgren
- Dept. of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Sweden
| | - Joanna Kaim
- Dept. of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Sweden
| | - Taufiqur Rahman Bhuiyan
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Marjahan Akhtar
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
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13
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Porter CK, Detizio KJ, Maier N, Testa KJ, Talaat KR, Chen WH, Lyon CE, Gutierrez RL, Frenck R, Isidean SD, Kaminski RW, Alcala AN, Hanevik K, Sawe F, Kirkpatrick BD, Louis Bourgeois A. A site assessment tool for inpatient controlled human infection models for enteric disease pathogens. Clin Trials 2021; 19:116-118. [PMID: 34708664 DOI: 10.1177/17407745211052473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The use of the controlled human infection model to facilitate product development and to advance understanding of host-pathogen interactions is of increasing interest. While administering a virulent (or infective) organism to a susceptible host necessitates an ongoing evaluation of safety and ethical considerations, a central theme in conducting these studies in a safe and ethical manner that yields actionable data is their conduct in facilities well-suited to address their unique attributes. To that end, we have developed a framework for evaluating potential sites in which to conduct inpatient enteric controlled human infection model to ensure consistency and increase the likelihood of success.
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Affiliation(s)
- Chad K Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - Katherine J Detizio
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | | | - Kayla J Testa
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Kawsar R Talaat
- Center for Immunization Research, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Wilbur H Chen
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Caroline E Lyon
- Vaccine Testing Center, Larner College of Medicine, The University of Vermont, Burlington, VT, USA
| | - Ramiro L Gutierrez
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - Robert Frenck
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Sandra D Isidean
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Robert W Kaminski
- Bacterial Disease Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Ashley N Alcala
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Kurt Hanevik
- Norwegian National Advisory Unit on Tropical Infectious Diseases, Department of Medicine, Haukeland University Hospital, Bergen, Norway.,Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Frederick Sawe
- Kenya Medical Research Institute and United States Army Medical Research Directorate-Africa, Kericho, Kenya.,Henry M. Jackson Foundation Medical Research International, Bethesda, MD, USA
| | - Beth D Kirkpatrick
- Vaccine Testing Center, Larner College of Medicine, The University of Vermont, Burlington, VT, USA
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14
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Porter CK, Talaat KR, Isidean SD, Kardinaal A, Chakraborty S, Gutiérrez RL, Sack DA, Bourgeois AL. The Controlled Human Infection Model for Enterotoxigenic Escherichia coli. Curr Top Microbiol Immunol 2021. [PMID: 34669040 DOI: 10.1007/82_2021_242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The controlled human infection model (CHIM) for enterotoxigenic Escherichia coli (ETEC) has been instrumental in defining ETEC as a causative agent of acute watery diarrhea, providing insights into disease pathogenesis and resistance to illness, and enabling preliminary efficacy evaluations for numerous products including vaccines, immunoprophylactics, and drugs. Over a dozen strains have been evaluated to date, with a spectrum of clinical signs and symptoms that appear to replicate the clinical illness seen with naturally occurring ETEC. Recent advancements in the ETEC CHIM have enhanced the characterization of clinical, immunological, and microbiological outcomes. It is anticipated that omics-based technologies applied to ETEC CHIMs will continue to broaden our understanding of host-pathogen interactions and facilitate the development of primary and secondary prevention strategies.
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Affiliation(s)
- Chad K Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, 20910, USA.
| | - Kawsar R Talaat
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Sandra D Isidean
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, 20910, USA
- Henry M. Jackson Foundation, Bethesda, MD, 20817, USA
| | - Alwine Kardinaal
- NIZO Food Research, Ede, P.O. Box 20, 6710 BA EDE, Kernhemseweg 2, 6718 ZB EDE, The Netherlands
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - Ramiro L Gutiérrez
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, 20910, USA
| | - David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD, 21205, USA
| | - A Louis Bourgeois
- PATH|Center for Vaccine Innovation and Access, 455 Massachusetts Avenue NW, Suite 1000, Washington, DC, 20001, USA
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15
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Lee T, Gutiérrez RL, Maciel M, Poole S, Testa KJ, Trop S, Duplessis C, Lane A, Riddle MS, Hamer M, Alcala A, Prouty M, Maier N, Erdem R, Louis Bourgeois A, Porter CK. Safety and immunogenicity of intramuscularly administered CS6 subunit vaccine with a modified heat-labile enterotoxin from enterotoxigenic Escherichia coli. Vaccine 2021; 39:5548-5556. [PMID: 34419306 PMCID: PMC8461560 DOI: 10.1016/j.vaccine.2021.08.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 08/05/2021] [Accepted: 08/09/2021] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Enterotoxigenic Escherichia coli (ETEC) is a common cause of infectious diarrhoea and a leading cause of morbidity and mortality in children living in resource-limited settings. It is also the leading cause of travellers' diarrhoea among civilian and military travellers. Its dual importance in global public health and travel medicine highlights the need for an effective vaccine. ETEC express colonization factors (CFs) that mediate adherence to the small intestine. An epidemiologically prevalent CF is coli surface antigen 6 (CS6). We assessed the safety and immunogenicity of a CS6-targeted candidate vaccine, CssBA, co-administered intramuscularly with the double-mutant heat-labile enterotoxin, dmLT [LT(R192G/L211A)]. METHODS This was an open-label trial. Fifty subjects received three intramuscular injections (Days 1, 22 and 43) of CssBA alone (5 µg), dmLT alone (0.1 µg) or CssBA (5, 15, 45 µg) + dmLT (0.1 and 0.5 µg). Subjects were actively monitored for adverse events for 28 days following the third vaccination. Antibody responses (IgG and IgA) were characterized in the serum and from lymphocyte supernatants (ALS) to CS6 and the native ETEC heat labile enterotoxin, LT. RESULTS Across all dose cohorts, the vaccine was safe and well-tolerated with no vaccine-related severe or serious adverse events. Among vaccine-related adverse events, a majority (98%) were mild with 79% being short-lived vaccine site reactions. Robust antibody responses were induced in a dose-dependent manner with a clear dmLT adjuvant effect. Response rates in subjects receiving 45 µg CssBA and 0.5 µg dmLT ranged from 50 to 100% across assays. CONCLUSION This is the first study to demonstrate the safety and immunogenicity of CssBA and/or dmLT administered intramuscularly. Co-administration of the two components induced robust immune responses to CS6 and LT, paving the way for future studies to evaluate the efficacy of this vaccine target and development of a multivalent, subunit ETEC vaccine.
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Affiliation(s)
- Tida Lee
- Enteric Diseases Department, Naval Medical Research Center, United States
| | - Ramiro L Gutiérrez
- Enteric Diseases Department, Naval Medical Research Center, United States
| | - Milton Maciel
- Enteric Diseases Department, Naval Medical Research Center, United States; Henry M. Jackson Foundation, United States
| | - Steven Poole
- Enteric Diseases Department, Naval Medical Research Center, United States; Henry M. Jackson Foundation, United States
| | - Kayla J Testa
- Enteric Diseases Department, Naval Medical Research Center, United States; Henry M. Jackson Foundation, United States
| | - Stefanie Trop
- Enteric Diseases Department, Naval Medical Research Center, United States; Henry M. Jackson Foundation, United States
| | | | - Alison Lane
- Uniformed Services University, United States
| | | | - Melinda Hamer
- Walter Reed Army Institute of Research, United States; Uniformed Services University, United States
| | - Ashley Alcala
- Enteric Diseases Department, Naval Medical Research Center, United States; Henry M. Jackson Foundation, United States
| | - Michael Prouty
- Enteric Diseases Department, Naval Medical Research Center, United States
| | | | | | | | - Chad K Porter
- Enteric Diseases Department, Naval Medical Research Center, United States.
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16
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Thorsing M, Krogh TJ, Vitved L, Nawrocki A, Jakobsen R, Larsen MR, Chakraborty S, Bourgeois AL, Andersen AZ, Boysen A. Linking inherent O-Linked Protein Glycosylation of YghJ to Increased Antigen Potential. Front Cell Infect Microbiol 2021; 11:705468. [PMID: 34490144 PMCID: PMC8417355 DOI: 10.3389/fcimb.2021.705468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/23/2021] [Indexed: 11/13/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is a WHO priority pathogen and vaccine target which causes infections in low-income and middle-income countries, travelers visiting endemic regions. The global urgent demand for an effective preventive intervention has become more pressing as ETEC strains have become increasingly multiple antibiotic resistant. However, the vaccine development pipeline has been slow to address this urgent need. To date, vaccine development has focused mainly on canonical antigens such as colonization factors and expressed toxins but due to genomic plasticity of this enteric pathogen, it has proven difficult to develop effective vaccines. In this study, we investigated the highly conserved non-canonical vaccine candidate YghJ/SsLE. Using the mass spectrometry-based method BEMAP, we demonstrate that YghJ is hyperglycosylated in ETEC and identify 54 O-linked Set/Thr residues within the 1519 amino acid primary sequence. The glycosylation sites are evenly distributed throughout the sequence and do not appear to affect the folding of the overall protein structure. Although the glycosylation sites only constitute a minor subpopulation of the available epitopes, we observed a notable difference in the immunogenicity of the glycosylated YghJ and the non-glycosylated protein variant. We can demonstrate by ELISA that serum from patients enrolled in an ETEC H10407 controlled infection study are significantly more reactive with glycosylated YghJ compared to the non-glycosylated variant. This study provides an important link between O-linked glycosylation and the relative immunogenicity of bacterial proteins and further highlights the importance of this observation in considering ETEC proteins for inclusion in future broad coverage subunit vaccine candidates.
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Affiliation(s)
| | | | - Lars Vitved
- Department of Cancer and Inflammation Research, University of Southern Denmark, Odense, Denmark
| | - Arkadiusz Nawrocki
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | | | - Martin R. Larsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Subhra Chakraborty
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - A. Louis Bourgeois
- Center for Vaccine Innovation and Access, PATH, Washington, DC, United States
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17
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Khalil I, Walker R, Porter CK, Muhib F, Chilengi R, Cravioto A, Guerrant R, Svennerholm AM, Qadri F, Baqar S, Kosek M, Kang G, Lanata C, Armah G, Wierzba T, Hasso-Agopsowicz M, Giersing B, Louis Bourgeois A. Enterotoxigenic Escherichia coli (ETEC) vaccines: Priority activities to enable product development, licensure, and global access. Vaccine 2021; 39:4266-4277. [PMID: 33965254 PMCID: PMC8273896 DOI: 10.1016/j.vaccine.2021.04.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 04/06/2021] [Accepted: 04/09/2021] [Indexed: 02/08/2023]
Abstract
Diarrhoeal disease attributable to enterotoxigenic Escherichia coli (ETEC) causes substantial morbidity and mortality predominantly in paediatric populations in low- and middle-income countries. In addition to acute illness, there is an increasing appreciation of the long-term consequences of enteric infections, including ETEC, on childhood growth and development. Provision of potable water and sanitation and appropriate clinical care for acute illness are critical to reduce the ETEC burden. However, these interventions are not always practical and may not achieve equitable and sustainable coverage. Vaccination may be the most cost-effective and equitable means of primary prevention; however, additional data are needed to accelerate the investment and guide the decision-making process for ETEC vaccines. First, to understand and quantify the ETEC disease burden, additional data are needed on the association between ETEC infection and physical and cognitive stunting as well as delayed educational attainment. Furthermore, the role of inappropriate or inadequate antibiotic treatment of ETEC-attributable diarrhoea may contribute to the development of antimicrobial resistance (AMR) and needs further elucidation. An ETEC vaccine that mitigates acute diarrhoeal illness and minimizes the longer-term disease manifestations could have significant public health impact and be a cost-effective countermeasure. Herein we review the ETEC vaccine pipeline, led by candidates compatible with the general parameters of the Preferred Product Characteristics (PPC) recently developed by the World Health Organization. Additionally, we have developed an ETEC Vaccine Development Strategy to provide a framework to underpin priority activities for researchers, funders and vaccine manufacturers, with the goal of addressing globally unmet data needs in the areas of research, product development, and policy, as well as commercialization and delivery. The strategy also aims to guide prioritization and co-ordination of the priority activities needed to minimize the timeline to licensure and use of ETEC vaccines, especially in in low- and middle-income countries, where they are most urgently needed.
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Affiliation(s)
| | | | | | | | - Roma Chilengi
- Centre for Infectious Disease Research in Zambia, Zambia
| | | | | | | | | | - Shahida Baqar
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, USA
| | | | | | | | - George Armah
- Noguchi Memorial Institute for Medical Research, Ghana
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18
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Talaat KR, Alaimo C, Martin P, Bourgeois AL, Dreyer AM, Kaminski RW, Porter CK, Chakraborty S, Clarkson KA, Brubaker J, Elwood D, Frölich R, DeNearing B, Weerts H, Feijoo BL, Halpern J, Sack D, Riddle MS, Fonck VG. Human challenge study with a Shigella bioconjugate vaccine: Analyses of clinical efficacy and correlate of protection. EBioMedicine 2021; 66:103310. [PMID: 33862589 PMCID: PMC8054157 DOI: 10.1016/j.ebiom.2021.103310] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/15/2021] [Accepted: 03/12/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Shigellosis is a major cause of moderate to severe diarrhoea and dysentery in children under 5 years of age in low and middle-income countries. The Flexyn2a vaccine conjugates the O-polysaccharide of Shigella flexneri 2a to Pseudomonas aeruginosa exotoxin A. We describe a Phase 2b proof-of-concept challenge study that evaluated safety, immunogenicity, and efficacy of the Flexyn2a vaccine to protect against shigellosis. METHODS In this randomized, double blind, placebo-controlled trial, healthy adults were randomized 1:1 to receive Flexyn2a (10 µg) or placebo intramuscularly, twice, 4 weeks apart, followed by challenge 4 weeks later with 1500 colony forming units (CFUs) of S. flexneri 2a strain 2457T. The primary outcome was vaccine-induced protection. S. flexneri 2a lipopolysaccharide (LPS)-specific immune responses were assessed. FINDINGS Sixty-seven subjects were enrolled, 34 received vaccine and 33 placebo. The vaccine was well tolerated; the majority of adverse events were mild in nature. Thirty vaccinees and 29 placebo recipients received the S. flexneri 2a challenge. Vaccination resulted in a 30.2% reduction in shigellosis compared with placebo (13/30 vs. 18/29; p = 0.11; 95% CI -15 to 62.6). Vaccine efficacy was more robust against severe disease, reaching 51.7% (p = 0.015, 95% CI 5.3 to 77.9) against moderate/severe diarrhoea or dysentery concurrent with fever or severe enteric symptoms and 72.4% (p = 0.07) against more severe diarrhoea (≥10 lose stools or ≥1000 g loose stools/24 h). Vaccinated subjects were less likely to need early antibiotic intervention following challenge (protective efficacy 51.7%, p = 0.01; 95% CI 9 to 76.8). In those who developed shigellosis, vaccinated subjects had a lower disease severity score (p = 0.002) than placebo-recipients. Additionally, LPS-specific serum IgG responses in Flexyn2a recipients were associated with protection against disease (p = 0.0016) and with a decreased shigellosis disease score (p = 0.002). INTERPRETATION The Flexyn2a bioconjugate vaccine was immunogenic, well tolerated and protected against severe illness after Shigella challenge and is a promising Shigella vaccine construct. We identified a strong association between anti-S. flexneri 2a serum IgG and a reduction in disease outcomes. (Clinicaltrials.gov, NCT02646371.) FUNDING: Funding for this study was through a grant from the Wellcome Trust.
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Affiliation(s)
- Kawsar R Talaat
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States.
| | | | | | - A Louis Bourgeois
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States; Now at PATH Center for Vaccine Innovation and Access, Washington, DC, United States
| | | | - Robert W Kaminski
- Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Chad K Porter
- Naval Medical Research Center, Silver Spring, MD, United States
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Kristen A Clarkson
- Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Jessica Brubaker
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Daniel Elwood
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | | | - Barbara DeNearing
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Hailey Weerts
- Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Brittany L Feijoo
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Jane Halpern
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - David Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Mark S Riddle
- Naval Medical Research Center, Silver Spring, MD, United States
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19
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Clarkson KA, Talaat KR, Alaimo C, Martin P, Bourgeois AL, Dreyer A, Porter CK, Chakraborty S, Brubaker J, Elwood D, Frölich R, DeNearing B, Weerts HP, Feijoo B, Halpern J, Sack D, Riddle MS, Fonck VG, Kaminski RW. Immune response characterization in a human challenge study with a Shigella flexneri 2a bioconjugate vaccine. EBioMedicine 2021; 66:103308. [PMID: 33813141 PMCID: PMC8047506 DOI: 10.1016/j.ebiom.2021.103308] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 02/13/2021] [Accepted: 03/12/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Diarrheal diseases are a leading cause of global morbidity and mortality affecting all ages, but especially children under the age of five in resource-limited settings. Shigella is a leading contributor to diarrheal diseases caused by bacterial pathogens and is considered a significant antimicrobial resistance threat. While improvements in hygiene, and access to clean water help as control measures, vaccination remains one of the most viable options for significantly reducing morbidity and mortality. METHODS Flexyn2a is a bioconjugate vaccine manufactured using novel conjugation methodologies enzymatically linking the O-polysaccharide of S. flexneri 2a to exotoxin A of Pseudomonas aeruginosa. The protective capacity of Flexyn2a was assessed in a controlled human infection model after two intramuscular immunizations. Immune responses pre- and post-immunization and/or infection were investigated and are described here. FINDINGS Flexyn2a induced lipopolysaccharide (LPS)-specific serum IgG responses post-immunization which were associated with protection against shigellosis. Additionally, several other immune parameters, including memory B cell responses, bactericidal antibodies and serum IgA, were also elevated in vaccinees protected against shigellosis. Immunization with Flexyn2a also induced gut-homing, LPS-specific IgG and IgA secreting B cells, indicating the vaccine induced immune effectors functioning at the site of intestinal infection. INTERPRETATION Collectively, the results of these immunological investigations provide insights into protective immune mechanisms post-immunization with Flexyn2a which can be used to further guide vaccine development and may have applicability to the larger Shigella vaccine field. FUNDING Funding for this study was provided through a Wellcome Trust grant.
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Affiliation(s)
- Kristen A Clarkson
- Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Kawsar R Talaat
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | | | | | | | | | - Chad K Porter
- Naval Medical Research Center, Silver Spring, MD, United States
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Jessica Brubaker
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Daniel Elwood
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | | | - Barbara DeNearing
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Hailey P Weerts
- Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States
| | - Brittany Feijoo
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Jane Halpern
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - David Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Mark S Riddle
- Naval Medical Research Center, Silver Spring, MD, United States
| | | | - Robert W Kaminski
- Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, MD, United States.
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20
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Brubaker J, Zhang X, Bourgeois AL, Harro C, Sack DA, Chakraborty S. Intestinal and systemic inflammation induced by symptomatic and asymptomatic enterotoxigenic E. coli infection and impact on intestinal colonization and ETEC specific immune responses in an experimental human challenge model. Gut Microbes 2021; 13:1-13. [PMID: 33645430 PMCID: PMC7919917 DOI: 10.1080/19490976.2021.1891852] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 02/02/2021] [Accepted: 02/08/2021] [Indexed: 02/07/2023] Open
Abstract
Recent studies have gained a better appreciation of the potential impacts of enteric infections beyond symptomatic diarrhea. It is recognized that infections by several enteropathogens could be associated with growth deficits in children and intestinal and systemic inflammation may play an important underlying role. With enterotoxigenic E. coli (ETEC) being one of the leading causes of diarrhea among children in the developing world and important contributor to stunting, a better understanding of the impact of ETEC infection beyond diarrhea is timely and greatly needed. To address this, we evaluated if ETEC infection induces intestinal and systemic inflammation and its impact on colonization and immune responses to ETEC vaccine-specific antigens in a dose descending experimental human challenge model using ETEC strain H10407. This study demonstrates that the concentrations of myeloperoxidase (MPO) in stool and intestinal fatty acid-binding protein (an indicator of compromised intestinal epithelial integrity) in serum, significantly increased following ETEC infection in both diarrhea and asymptomatic cases and the magnitudes and kinetics of MPO are dose and clinical outcome dependent. Cytokines IL-17A and IFN-γ were significantly increased in serum post-ETEC challenge. In addition, higher pre-challenge concentrations of cytokines IL-10 and GM-CSF were associated with protection from ETEC diarrhea. Interestingly, higher MPO concentrations were associated with higher intestinal colonization of ETEC and lower seroconversions of colonization factor I antigen, but the reverse was noted for seroconversions to heat-labile toxin B-subunit. Together this study has important implications for understanding the acute and long-term negative health outcomes associated with ETEC infection.
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Affiliation(s)
- Jessica Brubaker
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Xueyan Zhang
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - A. Louis Bourgeois
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
- PATH, Center for Vaccine Innovation and Access, Washington, DC, 20001, USA
| | - Clayton Harro
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - David A Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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21
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Talaat KR, Porter CK, Jaep KM, Duplessis CA, Gutierrez RL, Maciel M, Adjoodani B, Feijoo B, Chakraborty S, Brubaker J, Trop SA, Riddle MS, Joseph SS, Bourgeois AL, Prouty MG. Refinement of the CS6-expressing enterotoxigenic Escherichia coli strain B7A human challenge model: A randomized trial. PLoS One 2020; 15:e0239888. [PMID: 33264302 PMCID: PMC7710093 DOI: 10.1371/journal.pone.0239888] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 09/01/2020] [Indexed: 12/29/2022] Open
Abstract
Background Human challenge models for enterotoxigenic Escherichia coli (ETEC) facilitate vaccine down-selection. The B7A (O148:H28 CS6+LT+ST+) strain is important for vaccine development. We sought to refine the B7A model by identifying a dose and fasting regimen consistently inducing moderate-severe diarrhea. Methods An initial cohort of 28 subjects was randomized (1:1:1:1) to receive B7A following an overnight fast at doses of 108 or 109 colony forming units (cfu) or a 90-minute fast at doses of 109 or 1010 cfu. A second cohort included naïve and rechallenged subjects who had moderate-severe diarrhea and were given the target regimen. Immune responses to important ETEC antigens were assessed. Results Among subjects receiving 108 cfu of B7A, overnight fast, or 109 cfu, 90-minute fast, 42.9% (3/7) had moderate-severe diarrhea. Higher attack rates (71.4%; 5/7) occurred in subjects receiving 109 cfu, overnight fast, or 1010 cfu, 90-minute fast. Upon rechallenge with 109 cfu of B7A, overnight fast, 5/11 (45.5%) had moderate-severe diarrhea; the attack rate among concurrently challenge naïve subjects was 57.9% (11/19). Anti-CS6, O148 LPS and LT responses were modest across all groups. Conclusions An overnight fast enabled a reduction in the B7A inoculum dose; however, the attack rate was inconsistent and protection upon rechallenge was minimal.
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Affiliation(s)
- Kawsar R. Talaat
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
- * E-mail:
| | - Chad K. Porter
- Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Kayla M. Jaep
- Henry M. Jackson Foundation, Bethesda, MD, United States of America
| | | | | | - Milton Maciel
- Henry M. Jackson Foundation, Bethesda, MD, United States of America
| | - Brittany Adjoodani
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Brittany Feijoo
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Subhra Chakraborty
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Jessica Brubaker
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
| | - Stefanie A. Trop
- Henry M. Jackson Foundation, Bethesda, MD, United States of America
| | - Mark S. Riddle
- Naval Medical Research Center, Silver Spring, MD, United States of America
- Uniformed Services University of the Health Sciences, Bethesda, MD, United States of America
| | | | - A. Louis Bourgeois
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States of America
- PATH, Washington, DC, United States of America
| | - Michael G. Prouty
- Naval Medical Research Center, Silver Spring, MD, United States of America
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22
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Talaat KR, Porter CK, Bourgeois AL, Lee TK, Duplessis CA, Maciel M, Gutierrez RL, DeNearing B, Adjoodani B, Adkinson R, Testa KJ, Feijoo B, Alcala AN, Brubaker J, Beselman A, Chakraborty S, Sack D, Halpern J, Trop S, Wu H, Jiao J, Sullivan E, Riddle MS, Joseph SS, Poole ST, Prouty MG. Oral delivery of Hyperimmune bovine serum antibodies against CS6-expressing enterotoxigenic Escherichia coli as a prophylactic against diarrhea. Gut Microbes 2020; 12:1732852. [PMID: 32167011 PMCID: PMC7524165 DOI: 10.1080/19490976.2020.1732852] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND . Oral administration of bovine antibodies active against enterotoxigenic Escherichia coli (ETEC) have demonstrated safety and efficacy against diarrhea in human challenge trials. The efficacy of bovine serum immunoglobulins (BSIgG) against recombinant colonization factor CS6 or whole cell ETEC strain B7A was assessed against challenge with the CS6-expressing B7A. METHODS . This was a randomized, double-blind, placebo-controlled trial in which healthy adults received oral hyperimmune BSIgG anti-CS6, anti-B7A whole cell killed or non-hyperimmune BSIgG (placebo) in a 1:1:1 ratio then challenged with ETEC B7A. Two days pre-challenge, volunteers began a thrice daily, seven day course of immunoprophylaxis. On day 3, subjects received 1 × 1010 CFUs of B7A. Subjects were observed for safety and the primary endpoint of moderate-severe diarrhea (MSD). RESULTS . A total of 59 volunteers received product and underwent ETEC challenge. The BSIgG products were well-tolerated across all subjects. Upon challenge, 14/20 (70%) placebo recipients developed MSD, compared to 12/19 (63%; p = .74) receiving anti-CS6 BSIgG and 7/20 (35%; p = .06) receiving anti-B7A BSIgG. Immune responses to the ETEC infection were modest across all groups. CONCLUSIONS . Bovine-derived serum antibodies appear safe and well tolerated. Antibodies derived from cattle immunized with whole cell B7A provided 50% protection against MSD following B7A challenge; however, no protection was observed in subjects receiving serum antibodies targeting CS6. The lack of observed efficacy in this group may be due to low CS6 surface expression on B7A, the high dose challenge inoculum and/or the use of serum derived antibodies versus colostrum-derived antibodies.
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Affiliation(s)
- KR Talaat
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - CK Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA,CONTACT CK Porter Naval Medical Research Center, Silver Spring, MD, USA
| | - AL Bourgeois
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - TK Lee
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - CA Duplessis
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - M Maciel
- The Henry M. Jackson Foundation, Bethesda, MD, USA
| | - RL Gutierrez
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - B DeNearing
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - B Adjoodani
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - R Adkinson
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - KJ Testa
- The Henry M. Jackson Foundation, Bethesda, MD, USA
| | - B Feijoo
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - AN Alcala
- The Henry M. Jackson Foundation, Bethesda, MD, USA
| | - J Brubaker
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - A Beselman
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - S Chakraborty
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - D Sack
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - J Halpern
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - S Trop
- The Henry M. Jackson Foundation, Bethesda, MD, USA
| | - H Wu
- SAB Biotherapeutics Inc, Sioux Falls, SD, USA
| | - J Jiao
- SAB Biotherapeutics Inc, Sioux Falls, SD, USA
| | - E Sullivan
- SAB Biotherapeutics Inc, Sioux Falls, SD, USA
| | - MS Riddle
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
| | - SS Joseph
- The Henry M. Jackson Foundation, Bethesda, MD, USA
| | - ST Poole
- The Henry M. Jackson Foundation, Bethesda, MD, USA
| | - MG Prouty
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, USA
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23
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MacLennan CA, Riddle MS, Chen WH, Talaat KR, Jain V, Bourgeois AL, Frenck R, Kotloff K, Porter CK. Consensus Report on Shigella Controlled Human Infection Model: Clinical Endpoints. Clin Infect Dis 2020; 69:S591-S595. [PMID: 31816065 PMCID: PMC6901125 DOI: 10.1093/cid/ciz891] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Shigella controlled human infection model (CHIM) is valuable for assessing candidate Shigella vaccine efficacy and potentially accelerating regulatory approval. The Shigella CHIM is currently being conducted at 3 sites in the United States using Shigella flexneri 2a strain 2457T and Shigella sonnei strain 53G. Shigellosis can present variably as watery diarrhea alone or with dysentery, and can be accompanied by manifestations including fever, abdominal cramps, tenesmus, and malaise. For comparability, it is important to harmonize the primary clinical endpoint. An expert working group was convened on 2 February 2018 to review clinical data from Shigella CHIM studies performed to date and to develop a consensus primary endpoint. The consensus endpoint enabled "shigellosis" to present as severe diarrhea or moderate diarrhea or dysentery. The latter 2 criteria are met when concurrent with fever of 38.0°C and/or vomiting, and/or a constitutional/enteric symptom graded at least as "moderate" severity. The use of a blinded independent committee to adjudicate the primary endpoint by subject was also regarded as important. As safety of volunteers in challenge studies is of paramount importance and treatment timing can affect primary outcomes, a standard for early antibiotic administration was established as follows: (1) when the primary endpoint is met; (2) if a fever of ≥39.0°C develops; or (3) if the study physician deems it appropriate. Otherwise, antibiotics are given at 120 hours postinfectious challenge. The working group agreed on objective and subjective symptoms to be solicited, and standardized methods for assessing subject-reported severity of symptoms.
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Affiliation(s)
| | - Mark S Riddle
- F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda
| | - Wilbur H Chen
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland
| | - Kawsar R Talaat
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Varsha Jain
- Bill & Melinda Gates Foundation, Seattle, Washington
| | | | - Robert Frenck
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Ohio
| | - Karen Kotloff
- Division of Infectious Disease and Tropical Pediatrics, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore
| | - Chad K Porter
- Enteric Disease Department, Naval Medical Research Center, Silver Spring, Maryland
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24
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Kaminski RW, Pasetti MF, Aguilar AO, Clarkson KA, Rijpkema S, Bourgeois AL, Cohen D, Feavers I, MacLennan CA. Consensus Report on Shigella Controlled Human Infection Model: Immunological Assays. Clin Infect Dis 2020; 69:S596-S601. [PMID: 31816067 PMCID: PMC6901123 DOI: 10.1093/cid/ciz909] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Moderate to severe diarrhea caused by Shigella is a global health concern due to its substantial contribution to morbidity and mortality in children aged <5 years in low- and middle-income countries. Although antibiotic treatment can be effective, emerging antimicrobial resistance, limited access, and cost affirm the role of vaccines as the most attractive countermeasure. Controlled human infection models (CHIMs) represent a valuable tool for assessing vaccine efficacy and potentially accelerating licensure. Currently, immunological analysis during CHIM studies is customized based on vaccine type, regimen, and administration route. Additionally, differences in type of immunoassays and procedures used limit comparisons across studies. In November 2017, an expert working group reviewed Shigella CHIM studies performed to date and developed consensus guidelines on prioritization of immunoassays, specimens, and collection time points. Immunoassays were ranked into 3 tiers, with antibodies to Shigella lipopolysaccharide (LPS) being the highest priority. To facilitate comparisons across clinical studies, a second workshop was conducted in December 2017, which focused on the pathway toward a recognized enzyme-linked immunosorbent assay (ELISA) to determine serum immunoglobulin G titers against Shigella LPS. The consensus of the meeting was to establish a consortium of international institutions with expertise in Shigella immunology that would work with the National Institute for Biological Standards and Control to establish a harmonized ELISA, produce a reference sera, and identify a reliable source of Shigella LPS for global utilization. Herein we describe efforts toward establishing common procedures to advance Shigella vaccine development, support licensure, and ultimately facilitate vaccine deployment and uptake.
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Affiliation(s)
- Robert W Kaminski
- Subunit Enteric Vaccines and Immunology, Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring
| | - Marcela F Pasetti
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore
| | | | - Kristen A Clarkson
- Subunit Enteric Vaccines and Immunology, Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring
| | - Sjoerd Rijpkema
- Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, United Kingdom
| | | | - Dani Cohen
- School of Public Health, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | - Ian Feavers
- Division of Bacteriology, National Institute for Biological Standards and Control, Potters Bar, United Kingdom
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25
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Savarino SJ, McKenzie R, Tribble DR, Porter CK, O'Dowd A, Sincock SA, Poole ST, DeNearing B, Woods CM, Kim H, Grahek SL, Brinkley C, Crabb JH, Bourgeois AL. Hyperimmune Bovine Colostral Anti-CS17 Antibodies Protect Against Enterotoxigenic Escherichia coli Diarrhea in a Randomized, Doubled-Blind, Placebo-Controlled Human Infection Model. J Infect Dis 2020; 220:505-513. [PMID: 30897198 DOI: 10.1093/infdis/jiz135] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 03/20/2019] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Enterotoxigenic Escherichia coli (ETEC) commonly cause diarrhea in children living in developing countries and in travelers to those regions. ETEC are characterized by colonization factors (CFs) that mediate intestinal adherence. We assessed if bovine colostral IgG (bIgG) antibodies against a CF, CS17, or antibodies against CsbD, the minor tip subunit of CS17, would protect subjects against diarrhea following challenge with a CS17-expressing ETEC strain. METHODS Adult subjects were randomized (1:1:1) to receive oral bIgG against CS17, CsbD, or placebo. Two days prior to challenge, subjects began dosing 3 times daily with the bIgG products (or placebo). On day 3, subjects ingested 5 × 109 cfu ETEC strain LSN03-016011/A in buffer. Subjects were assessed for diarrhea for 120 hours postchallenge. RESULTS A total of 36 subjects began oral prophylaxis and 35 were challenged with ETEC. While 50.0% of the placebo recipients had watery diarrhea, none of the subjects receiving anti-CS17 had diarrhea (P = .01). In contrast, diarrhea rates between placebo and anti-CsbD recipients (41.7%) were comparable (P = 1.0). CONCLUSIONS This is the first study to demonstrate anti-CS17 antibodies provide significant protection against ETEC expressing CS17. More research is needed to better understand why anti-CsbD was not comparably efficacious. Clinical Trials Registration. NCT00524004.
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Affiliation(s)
| | - Robin McKenzie
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Johns Hopkins School of Medicine, Baltimore, Maryland
| | | | - Chad K Porter
- Naval Medical Research Center, Silver Spring, Maryland
| | | | | | | | - Barbara DeNearing
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Hye Kim
- Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Shannon L Grahek
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Carl Brinkley
- Walter Reed Army Institute of Research, Silver Spring, Maryland
| | | | - A Louis Bourgeois
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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26
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Talaat KR, Bourgeois AL, Frenck RW, Chen WH, MacLennan CA, Riddle MS, Suvarnapunya AE, Brubaker JL, Kotloff KL, Porter CK. Consensus Report on Shigella Controlled Human Infection Model: Conduct of Studies. Clin Infect Dis 2019; 69:S580-S590. [PMID: 31816068 PMCID: PMC6901126 DOI: 10.1093/cid/ciz892] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Shigella causes morbidity and mortality worldwide, primarily affecting young children living in low-resource settings. It is also of great concern due to increasing antibiotic resistance, and is a priority organism for the World Health Organization. A Shigella vaccine would decrease the morbidity and mortality associated with shigellosis, improve child health, and decrease the need for antibiotics. Controlled human infection models (CHIMs) are useful tools in vaccine evaluation for early up- or down-selection of vaccine candidates and potentially useful in support of licensure. Over time, the methods employed in these models have become more uniform across sites performing CHIM trials, although some differences in conduct persist. In November 2017, a Shigella CHIM workshop was convened in Washington, District of Columbia. Investigators met to discuss multiple aspects of these studies, including study procedures, clinical and immunological endpoints, and shared experiences. This article serves as a uniform procedure by which to conduct Shigella CHIM studies.
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Affiliation(s)
- Kawsar R Talaat
- Center for Immunization Research, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Robert W Frenck
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Wilbur H Chen
- Center for Vaccine Development, University of Maryland School of Medicine, Baltimore
| | | | - Mark S Riddle
- F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda
| | - Akamol E Suvarnapunya
- Department of Enteric Infections, Bacterial Diseases Branch, Walter Reed Army Institute of Research, Silver Spring
| | - Jessica L Brubaker
- Global Disease Epidemiology and Control Program, Department of International Health, Johns Hopkins Bloomberg School of Public Health
| | - Karen L Kotloff
- Division of Infectious Disease and Tropical Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore
| | - Chad K Porter
- Enteric Disease Department, Naval Medical Research Center, Silver Spring, Maryland
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27
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Seo H, Lu T, Mani S, Bourgeois AL, Walker R, Sack DA, Zhang W. Adjuvant effect of enterotoxigenic Escherichia coli (ETEC) double-mutant heat-labile toxin (dmLT) on systemic immunogenicity induced by the CFA/I/II/IV MEFA ETEC vaccine: Dose-related enhancement of antibody responses to seven ETEC adhesins (CFA/I, CS1-CS6). Hum Vaccin Immunother 2019; 16:419-425. [PMID: 31361177 PMCID: PMC7062417 DOI: 10.1080/21645515.2019.1649555] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Double-mutant heat-labile toxin (dmLT, LTR192G/L211A) of enterotoxigenic Escherichia coli (ETEC) is an effective mucosal adjuvant. Recent studies have shown that dmLT also exhibits adjuvanticity for antigens administered parenterally. In this study, we subcutaneously (SC) immunized mice with the ETEC adhesin-based vaccine, CFA/I/II/IV MEFA (multiepitope fusion antigen), adjuvanted with dmLT and examined the impact of dmLT on antibody responses specific to the seven adhesins in the vaccine construction [CFA/I, CFA/II (CS1, CS2, CS3) and CFA/IV (CS4, CS5, CS6)]. Mice were immunized with a fixed dose of CFA/I/II/IV MEFA and ascending doses of dmLT adjuvant (0, 0.05, 0.1, 0.5 or 1.0 µg) to assess the potential dmLT dose response relationship. Data showed that dmLT enhanced systemic antibody responses to all seven antigens (CFA/I, CS1-CS6) targeted by MEFA in a dose-dependent way. The adjuvant effect of dmLT on the MEFA construct plateaued at a dose of 0.1 µg. Results also indicated that dmLT is an effective parenteral adjuvant when given by the SC route with the ETEC adhesin MEFA vaccine and that antibody enhancement was achieved with relatively low doses. These observations suggest the potential usefulness of dmLT for parenteral ETEC vaccine candidates and also perhaps for vaccines against other pathogens.
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Affiliation(s)
- Hyesuk Seo
- Diagnostic Medicine/Pathobiology Department, Kansas State University College of Veterinary Medicine, Manhattan, KS, USA.,Department of Pathobiology, University of Illinois at Urbana-Champaign, Illinois, Il, USA
| | - Ti Lu
- Diagnostic Medicine/Pathobiology Department, Kansas State University College of Veterinary Medicine, Manhattan, KS, USA
| | - Sachin Mani
- PATH, Center for Vaccine Innovation and Access, Washington, DC, USA
| | | | - Richard Walker
- PATH, Center for Vaccine Innovation and Access, Washington, DC, USA
| | - David A Sack
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Weiping Zhang
- Diagnostic Medicine/Pathobiology Department, Kansas State University College of Veterinary Medicine, Manhattan, KS, USA.,Department of Pathobiology, University of Illinois at Urbana-Champaign, Illinois, Il, USA
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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 2019; 129:2980. [PMID: 31259744 DOI: 10.1172/jci130874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Harro C, Louis Bourgeois A, Sack D, Walker R, DeNearing B, Brubaker J, Maier N, Fix A, Dally L, Chakraborty S, Clements JD, Saunders I, Darsley MJ. Live attenuated enterotoxigenic Escherichia coli (ETEC) vaccine with dmLT adjuvant protects human volunteers against virulent experimental ETEC challenge. Vaccine 2019; 37:1978-1986. [PMID: 30797634 PMCID: PMC6434318 DOI: 10.1016/j.vaccine.2019.02.025] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 02/12/2019] [Accepted: 02/14/2019] [Indexed: 01/10/2023]
Abstract
Background There is no licensed vaccine against enterotoxigenic Escherichia coli (ETEC), a major cause of diarrhea-associated morbidity and mortality among infants and children in low-income countries and travelers. The results of this vaccination/challenge study demonstrate strong protection by an attenuated ETEC vaccine candidate, ACE527, when co-administered with a mucosal adjuvant, the double-mutant heat-labile toxin (dmLT) of ETEC. Methods Sixty healthy adults participated in a randomized, placebo-controlled, double-blind study with three doses of lyophilized ACE527 (∼3 × 109 of each strain per dose) administered orally with or without dmLT adjuvant (25 µg/dose). Six months later, 36 of these volunteers and a control group of 21 unvaccinated volunteers were challenged with virulent ETEC strain H10407. The primary outcome was severe diarrhea, defined as passing >800 g of unformed stools during the inpatient period following challenge. Findings The vaccine was well tolerated and induced robust immune responses to key antigens. The protective efficacy (PE) against the primary outcome of severe diarrhea was 65.9% (95% confidence interval [CI] 5.4–87.7, p = 0.003). Among subjects receiving the adjuvanted vaccine, the attack rate of severe diarrhea was 23.1, while in unimmunized controls it was 67.7%. The PE against diarrhea of any severity was 58.5% (95% CI 3.8– 82.1, p = 0.016). There was a strong inverse correlation between shedding of the vaccine strain after either of the first two doses and absence of severe diarrhea upon challenge (RR = 0.29, 95% CI 0.08–1.05, p = 0.041). Challenge strain shedding was 10-fold lower in those receiving the adjuvant than in those receiving vaccine alone. The unadjuvanted vaccine was not protective (PE = 23.1%). Interpretation The results of this study support further development of ACE527 + dmLT as a vaccine for children in endemic countries and travelers. This is the first clinical demonstration that dmLT can contribute significantly to vaccine efficacy and may warrant testing with other oral vaccines. (ClinicalTrials.gov registration: NCT01739231).
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Affiliation(s)
- Clayton Harro
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | - David Sack
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | - Barbara DeNearing
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Jessica Brubaker
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | | | - Len Dally
- The Emmes Corporation, Rockville, MD, USA
| | - Subhra Chakraborty
- Center for Immunization Research, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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Bernstein DI, Pasetti MF, Brady R, Buskirk AD, Wahid R, Dickey M, Cohen M, Baughman H, El-Khorazaty J, Maier N, Sztein MB, Baqar S, Bourgeois AL. A Phase 1 dose escalating study of double mutant heat-labile toxin LTR192G/L211A (dmLT) from Enterotoxigenic Escherichia coli (ETEC) by sublingual or oral immunization. Vaccine 2018; 37:602-611. [PMID: 30563789 DOI: 10.1016/j.vaccine.2018.12.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/05/2018] [Accepted: 12/06/2018] [Indexed: 11/27/2022]
Abstract
BACKGROUND The public health burden of Enterotoxigenic Escherichia coli (ETEC) is high but no vaccine is specifically approved to prevent ETEC infections. METHODS We performed a Phase 1, dose escalation study (1-50 µg) evaluating the sublingual (SL) delivery of the double mutant heat-labile toxin LTR192G/L211A (dmLT) in 80 healthy adult volunteers. The primary objective was safety and the secondary was the immunogenicity of the dmLT. Subjects received 3 doses of dmLT at days 1, 15, and 29. Subjects receiving the first dose at each dosage level were observed overnight in a research facility. The second and third doses were administered on an outpatient basis. Data from cohorts 1-4 were used to select the cohort 5 dose (25 µg), comparing SL and oral routes. RESULTS The vaccine appeared safe and well tolerated with only rare development of vomiting or diarrhea. The serum anti-dmLT IgA and IgG and neutralizing antibody responses were modest after any of the SL immunizations. Serum IgA and IgG titers were increased at the higher antigen doses (25 or 50 µg) but the percent with 4-fold increases was at best 38% for both IgA and IgG. The 4-fold increase among subjects receiving all 3 doses was 43% for both IgA and IgG. Antibody titers following oral administration were, in general, significantly higher than after SL. The frequency of IgA- or IgG-ASCs in circulation were somewhat vaccine dose dependent and were detected at a moderate level. However, antibodies in saliva or stool were rarely detected. Post-vaccination increases in T cells or cytokine production were also infrequent. CONCLUSION The dmLT vaccine formulation evaluated here was safe but only moderately immunogenic at doses up to 50 µg when administered by the SL or oral route. Studies at higher doses with better formulations appear warranted.
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Affiliation(s)
- David I Bernstein
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.
| | - Marcela F Pasetti
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Rebecca Brady
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Amanda D Buskirk
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Rezwanul Wahid
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Michelle Dickey
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Mitchell Cohen
- Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | | | | | | | - Marcelo B Sztein
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Shahida Baqar
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
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Akhtar M, Chowdhury MI, Bhuiyan TR, Kaim J, Ahmed T, Rafique TA, Khan A, Rahman SIA, Khanam F, Begum YA, Sharif MZ, Islam LN, Carlin N, Maier N, Fix A, Wierzba TF, Walker RI, Bourgeois AL, Svennerholm AM, Qadri F, Lundgren A. Evaluation of the safety and immunogenicity of the oral inactivated multivalent enterotoxigenic Escherichia coli vaccine ETVAX in Bangladeshi adults in a double-blind, randomized, placebo-controlled Phase I trial using electrochemiluminescence and ELISA assays for immunogenicity analyses. Vaccine 2018; 37:5645-5656. [PMID: 30473185 PMCID: PMC6717083 DOI: 10.1016/j.vaccine.2018.11.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Revised: 10/25/2018] [Accepted: 11/14/2018] [Indexed: 12/22/2022]
Abstract
The safety and immunogenicity of the second generation oral enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX, consisting of inactivated recombinant E. coli strains over-expressing the colonization factors (CFs) CFA/I, CS3, CS5 and CS6 and the heat labile toxoid LCTBA, were evaluated in Bangladeshi volunteers. To enable analysis of antibody responses against multiple vaccine antigens for subsequent use in small sample volumes from children, a sensitive electrochemiluminescence (ECL) assay for analysis of intestine-derived antibody-secreting cell responses using the antibodies in lymphocyte secretions (ALS) assay was established using Meso Scale Discovery technology. Three groups of Bangladeshi adults (n = 15 per group) received two oral doses of ETVAX with or without double mutant LT (dmLT) adjuvant or placebo in the initial part of a randomized, double-blind, placebo-controlled, age-descending, dose-escalation trial. CF- and LTB-specific ALS and plasma IgA responses were analyzed by ECL and/or ELISA. ETVAX was safe and well tolerated in the adults. Magnitudes of IgA ALS responses determined by ECL and ELISA correlated well (r = 0.85 to 0.98 for the five primary antigens, P < 0.001) and ECL was selected as the ALS readout method. ALS IgA responses against each of the primary antigens were detected in 87-100% of vaccinees after the first and in 100% after the second vaccine dose. Plasma IgA responses against different CFs and LTB were observed in 62-93% and 100% of vaccinees, respectively. No statistically significant adjuvant effect of dmLT on antibody responses to any antigen was detected, but the overall antigenic breadth of the plasma IgA response tended to favor the adjuvanted vaccine when responses to 4 or more or 5 vaccine antigens were considered. Responses in placebo recipients were infrequent and mainly detected against single antigens. The promising results in adults supported testing ETVAX in descending age groups of children. ClinicalTrials.gov Identifier: NCT02531802.
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Affiliation(s)
- Marjahan Akhtar
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Mohiul I Chowdhury
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Taufiqur R Bhuiyan
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Joanna Kaim
- GUVAX (Gothenburg University Vaccine Research Institute), Dept. of Microbiology and Immunology, Inst. of Biomedicine, University of Gothenburg, Sweden
| | - Tasnuva Ahmed
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Tanzeem A Rafique
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Arifuzzaman Khan
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Sadia I A Rahman
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Farhana Khanam
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Yasmin A Begum
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Mir Z Sharif
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Laila N Islam
- Dept. of Biochemistry and Molecular Biology, University of Dhaka, Bangladesh
| | | | | | | | | | | | | | - Ann-Mari Svennerholm
- GUVAX (Gothenburg University Vaccine Research Institute), Dept. of Microbiology and Immunology, Inst. of Biomedicine, University of Gothenburg, Sweden
| | - Firdausi Qadri
- icddr,b (International Centre for Diarrhoeal Disease Research, Bangladesh), Dhaka, Bangladesh
| | - Anna Lundgren
- GUVAX (Gothenburg University Vaccine Research Institute), Dept. of Microbiology and Immunology, Inst. of Biomedicine, University of Gothenburg, Sweden.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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33
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Chakraborty S, Harro C, DeNearing B, Brubaker J, Connor S, Maier N, Dally L, Flores J, Bourgeois AL, Walker R, Sack DA. Impact of lower challenge doses of enterotoxigenic Escherichia coli on clinical outcome, intestinal colonization and immune responses in adult volunteers. PLoS Negl Trop Dis 2018; 12:e0006442. [PMID: 29702652 PMCID: PMC5942845 DOI: 10.1371/journal.pntd.0006442] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 05/09/2018] [Accepted: 04/10/2018] [Indexed: 11/18/2022] Open
Abstract
A reliable and effective human challenge model is needed to help down-select the most promising ETEC vaccines currently under development. Such a model would need to reliably induce diarrhea in a high proportion of volunteers using the lowest possible inoculum to maximize safety and sensitivity. Previously we validated a challenge model that utilized a dose of 2x107 CFU of ETEC strain H10407 (LT+, ST+, CFA/I+ and O78+) to induce attack rates for moderate to severe diarrhea (MSD) of ~60-70%. Here we detail efforts to further refine the model in an attempt to determine if a lower challenge dose of H10407 can be used. Thirty subjects were randomized 1:1 to receive an oral administration of H10407 at doses of 106 or 105 CFU in bicarbonate buffer. After challenge, subjects were monitored for signs and symptoms of enteric illness and stool samples were collected to detect shedding of the challenge strain. Systemic and mucosal immune responses were measured using serum, antibody in lymphocyte supernatant and fecal samples. The attack rate was 13.3% (2/15) and 26.7% (4/15) for MSD in the 105 and 106 groups, respectively. Four MSD cases met criteria for early antibiotic treatment. All subjects but one shed the challenge strain in fecal samples. The frequency and magnitude of anti-LT toxin, CFA/I and LPS O78 immune responses were antigen, dose, severity of diarrhea and shedding levels dependent. Notably, although of lower magnitude, there were considerable immune responses in the subjects with no diarrhea. This may indicate that immune responses to asymptomatic infections of ETEC in children in the endemic countries may contribute to protection. Based on this and our prior studies, we conclude that a dose of 2x107 H10407 remains the lowest practical dose for use in future volunteer studies evaluating candidate vaccines and other preventive or therapeutic ETEC interventions. TRIAL REGISTRATION ClinicalTrials.gov NCT00844493.
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Affiliation(s)
- Subhra Chakraborty
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- * E-mail:
| | - Clayton Harro
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Barbara DeNearing
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Jessica Brubaker
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Sean Connor
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | | | - Len Dally
- The EMMES Corporation, Rockville, Maryland, United States of America
| | | | - A. Louis Bourgeois
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- PATH, Washington, DC, United States of America
| | | | - David A. Sack
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
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Porter CK, Lynen A, Riddle MS, Talaat K, Sack D, Gutiérrez RL, McKenzie R, DeNearing B, Feijoo B, Kaminski RW, Taylor DN, Kirkpatrick BD, Bourgeois AL. Clinical endpoints in the controlled human challenge model for Shigella: A call for standardization and the development of a disease severity score. PLoS One 2018; 13:e0194325. [PMID: 29590182 PMCID: PMC5874036 DOI: 10.1371/journal.pone.0194325] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 02/28/2018] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Since 1946 the controlled human infection model (CHIM) for Shigella has been used to improve understanding of disease pathogenesis, describe clinical and immunologic responses to infection and as a tool for vaccine development. As the frequency and intent for use in vaccine comparisons increases, standardization of the primary endpoint definition is necessary. METHODS Subject-level data were obtained from previously conducted experimental Shigella CHIM studies. Signs and symptoms severity were categorized consistently across all studies. Sign and symptom correlations were estimated and univariate models were utilized to describe the association between stool output and other Shigella-attributable signs and symptoms. Multiple correspondence and hierarchical clustering analyses were performed to describe the co-occurrence of signs and symptoms. A disease score is proposed based on the co-occurrence of these events. RESULTS Data were obtained on 54 subjects receiving 800 to 2000 colony forming units (cfu) of S. flexneri. The median maximum 24 hour stool output was 514 ml (IQR: 300, 998 ml) with a median frequency of 6 (IQR: 4, 9). Subjects reported abdominal pain or cramps (81.5%), headache (66.7%) and anorexia (64.8%), 50.0% had a fever and 27.8% had gross blood in multiple loose stools. Multiple correspondence analyses highlighted co-occurrence of symptoms based on severity. A 3-parameter disease severity score predicted shigellosis endpoints and better differentiated disease spectrum. CONCLUSION Dichotomous endpoints for Shigella CHIM fail to fully account for disease variability. An ordinal disease score characterizing the breadth of disease severity may enable a better characterization of shigellosis and can decrease sample size requirements. Furthermore, the disease severity score may be a useful tool for portfolio management by enabling prioritization across vaccine candidates with comparable efficacy estimates using dichotomous endpoints.
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Affiliation(s)
- Chad K. Porter
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
- * E-mail:
| | - Amanda Lynen
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Mark S. Riddle
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Kawsar Talaat
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - David Sack
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Ramiro L. Gutiérrez
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Robin McKenzie
- School of Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| | - Barbara DeNearing
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Brittany Feijoo
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Robert W. Kaminski
- Department of Enteric Infections, Walter Reed Army Institute of Research, Silver Spring, MD, United States of America
| | - David N. Taylor
- Drug Development Global Program, PATH, Seattle, WA, United States of America
| | - Beth D. Kirkpatrick
- University of Vermont College of Medicine, Vaccine Testing Center, Department of Medicine, Burlington, VT, United States of America
| | - A. Louis Bourgeois
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
- Enteric Vaccine Initiative, PATH, Washington, DC, United States of America
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Walker RI, Wierzba TF, Mani S, Bourgeois AL. Vaccines against Shigella and enterotoxigenic Escherichia coli: A summary of the 2016 VASE Conference. Vaccine 2017; 35:6775-6782. [PMID: 28987444 DOI: 10.1016/j.vaccine.2017.09.045] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 09/05/2017] [Accepted: 09/13/2017] [Indexed: 11/25/2022]
Abstract
PATH hosted the inaugural Vaccines Against Shigella and Enterotoxigenic Escherichia coli (VASE) Conference in Washington, DC in June 2016, bringing together experts from around the world for a highly collaborative forum to discuss progress in the development of new enteric vaccines. Diarrheal disease and long-term sequelae caused by infections with the bacterial pathogens Shigella and enterotoxigenic E. coli (ETEC) pose a significant public health burden in low-income communities. There are currently no licensed vaccines against these pathogens, and the global health community has recently prioritized their development. The 2016 VASE Conference aimed to accelerate communication and progress among those working in the enteric vaccine field to make Shigella and ETEC vaccines a reality as quickly as possible. Research presented in oral and poster presentations at the VASE Conference covered a range of topics, including: the global burden of disease and public health case for Shigella and ETEC vaccines; current vaccine candidates in development; immunology and host responses to the pathogens; and the rationale for and status of combined Shigella-ETEC vaccine candidates. This article reviews key points and highlighted research presented in each of the plenary conference sessions and poster presentations at the 2016 conference. Planning for the 2018 VASE Conference is underway and will likely provide an important platform for sharing the latest updates on Shigella and ETEC vaccine research efforts and maintaining the momentum for accelerating this work. It is also expected that the VASE Conference will continue to provide a unique opportunity for those in the enteric vaccine field to share ideas, make connections, and create workable plans to make Shigella and ETEC vaccines a reality. (Updates available at: www.vaseconference.org.).
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Affiliation(s)
| | | | | | - A Louis Bourgeois
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
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Savarino SJ, McKenzie R, Tribble DR, Porter CK, O'Dowd A, Cantrell JA, Sincock SA, Poole ST, DeNearing B, Woods CM, Kim H, Grahek SL, Brinkley C, Crabb JH, Bourgeois AL. Prophylactic Efficacy of Hyperimmune Bovine Colostral Antiadhesin Antibodies Against Enterotoxigenic Escherichia coli Diarrhea: A Randomized, Double-Blind, Placebo-Controlled, Phase 1 Trial. J Infect Dis 2017; 216:7-13. [PMID: 28541500 DOI: 10.1093/infdis/jix144] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/17/2017] [Indexed: 11/13/2022] Open
Abstract
Background Tip-localized adhesive proteins of bacterial fimbriae from diverse pathogens confer protection in animal models, but efficacy in humans has not been reported. Enterotoxigenic Escherichia coli (ETEC) commonly elaborate colonization factors comprising a minor tip adhesin and major stalk-forming subunit. We assessed the efficacy of antiadhesin bovine colostral IgG (bIgG) antibodies against ETEC challenge in volunteers. Methods Adults were randomly assigned (1:1:1) to take oral hyperimmune bIgG raised against CFA/I minor pilin subunit (CfaE) tip adhesin or colonization factor I (CFA/I) fimbraie (positive control) or placebo. Two days before challenge, volunteers began a thrice-daily, 7-day course of investigational product administered in sodium bicarbonate 15 minutes after each meal. On day 3, subjects drank 1 × 109 colony-forming units of colonization factor I (CFA/I)-ETEC strain H10407 with buffer. The primary efficacy endpoint was diarrhea within 120 hours of challenge. Results After enrollment and randomization, 31 volunteers received product, underwent ETEC challenge, and were included in the per protocol efficacy analysis. Nine of 11 placebos developed diarrhea, 7 experiencing moderate to severe disease. Protective efficacy of 63% (P = .03) and 88% (P = .002) was observed in the antiadhesin bIgG and positive control groups, respectively. Conclusions Oral administration of anti-CFA/I minor pilin subunit (CfaE) antibodies conferred significant protection against ETEC, providing the first clinical evidence that fimbrial tip adhesins function as protective antigens.
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Affiliation(s)
| | - Robin McKenzie
- Johns Hopkins Bloomberg School of Public Health.,Johns Hopkins School of Medicine, Baltimore
| | | | - Chad K Porter
- Naval Medical Research Center, Silver Spring, Maryland
| | | | | | | | | | | | | | - Hye Kim
- Johns Hopkins School of Medicine, Baltimore
| | | | - Carl Brinkley
- Walter Reed Army Institute of Research, Silver Spring, Maryland
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Porter CK, Louis Bourgeois A, Frenck RW, Prouty M, Maier N, Riddle MS. Developing and utilizing controlled human models of infection. Vaccine 2017; 35:6813-6818. [PMID: 28583306 DOI: 10.1016/j.vaccine.2017.05.068] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 04/11/2017] [Accepted: 05/24/2017] [Indexed: 11/18/2022]
Abstract
The controlled human infection model (CHIM) to assess the efficacy of vaccines against Shigella and enterotoxigenic Escherichia coli (ETEC) has several unique features that could significantly enhance the ability to test candidate vaccines. Despite increasing interest in these models, questions remain as to how to best incorporate them into vaccine development and how to maximize results. We designed a workshop focused on CHIM as part of the Vaccines Against Shigella and ETEC (VASE) Conference. The workshop, using the World Café method, focused on; clinical outcomes, nonclinical outcomes and model standardization. Researchers with a variety of expertise and experience rotated through each focus area and discussed relevant sub-topics. The results of these discussions were presented and questions posed to guide future workshops. Clinical endpoint discussions focused on the need for harmonized definitions; optimized attack rates; difficulties of sample collection and a need for non-stool based endpoints. Nonclinical discussions centered on evolving omics-based opportunities, host predictors of susceptibility and novel characterizations of the immune response. Model standardization focused on the value of shared procedures across institutions for clinical and non-clinical endpoints as well as for strain preparation and administration and subject selection. Participants agreed CHIMs for Shigella and ETEC vaccine development could accelerate vaccine development of a promising candidate; however, it was also appreciated that variability in the model and our limited understand of the host-pathogen interaction may yield results that could negatively impact a suitable candidate. Future workshops on CHIM are needed to ensure the optimal application of these models moving forward.
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Affiliation(s)
- Chad K Porter
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States.
| | - A Louis Bourgeois
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States
| | - Robert W Frenck
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Michael Prouty
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
| | | | - Mark S Riddle
- Enteric Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States
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Porter CK, Riddle MS, Alcala AN, Sack DA, Harro C, Chakraborty S, Gutierrez RL, Savarino SJ, Darsley M, McKenzie R, DeNearing B, Steinsland H, Tribble DR, Bourgeois AL. An Evidenced-Based Scale of Disease Severity following Human Challenge with Enteroxigenic Escherichia coli. PLoS One 2016; 11:e0149358. [PMID: 26938983 PMCID: PMC4777366 DOI: 10.1371/journal.pone.0149358] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 01/29/2016] [Indexed: 11/30/2022] Open
Abstract
Background Experimental human challenge models have played a major role in enhancing our understanding of infectious diseases. Primary outcomes have typically utilized overly simplistic outcomes that fail to entirely account for complex illness syndromes. We sought to characterize clinical outcomes associated with experimental infection with enterotoxigenic Escherichia coli (ETEC) and to develop a disease score. Methods Data were obtained from prior controlled human ETEC infection studies. Correlation and univariate regression across sign and symptom severity was performed. A multiple correspondence analysis was conducted. A 3-parameter disease score with construct validity was developed in an iterative fashion, compared to standard outcome definitions and applied to prior vaccine challenge trials. Results Data on 264 subjects receiving seven ETEC strains at doses from 1x105 to 1x1010 cfu were used to construct a standardized dataset. The strongest observed correlation was between vomiting and nausea (r = 0.65); however, stool output was poorly correlated with subjective activity-impacting outcomes. Multiple correspondence analyses showed covariability in multiple signs and symptoms, with severity being the strongest factor corresponding across outcomes. The developed disease score performed well compared to standard outcome definitions and differentiated disease in vaccinated and unvaccinated subjects. Conclusion Frequency and volumetric definitions of diarrhea severity poorly characterize ETEC disease. These data support a disease severity score accounting for stool output and other clinical signs and symptoms. Such a score could serve as the basis for better field trial outcomes and gives an additional outcome measure to help select future vaccines that warrant expanded testing in pivotal pre-licensure trials.
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Affiliation(s)
- Chad K. Porter
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
- * E-mail:
| | - Mark S. Riddle
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Ashley N. Alcala
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - David A. Sack
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Clayton Harro
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Subhra Chakraborty
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Ramiro L. Gutierrez
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | - Stephen J. Savarino
- Enteric Disease Department, Infectious Disease Directorate, Naval Medical Research Center, Silver Spring, MD, United States of America
| | | | - Robin McKenzie
- School of Medicine, Johns Hopkins University, Baltimore, MD, United States of America
| | - Barbara DeNearing
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
| | - Hans Steinsland
- Centre for Intervention Science in Maternal and Child Health (CISMAC), Centre for International Health, and Department of Biomedicine, University of Bergen, Bergen, Norway
| | - David R. Tribble
- Infectious Disease Clinical Research Program, Bethesda, MD, United States of America
| | - A. Louis Bourgeois
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States of America
- PATH, Washington, DC, United States of America
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Lamberti LM, Bourgeois AL, Fischer Walker CL, Black RE, Sack D. Estimating diarrheal illness and deaths attributable to Shigellae and enterotoxigenic Escherichia coli among older children, adolescents, and adults in South Asia and Africa. PLoS Negl Trop Dis 2014; 8:e2705. [PMID: 24551265 PMCID: PMC3923718 DOI: 10.1371/journal.pntd.0002705] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 01/05/2014] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION While Shigellae and strains of enterotoxigenic Escherichia coli (ETEC) are important causes of diarrhea-associated morbidity and mortality among infants and young children (<5 years of age), their health impact in older age groups is unclear. We sought to quantify the overall burden of shigellosis and ETEC diarrhea among older children, adolescents, and adults in Africa and South Asia, the two regions with the highest levels of diarrhea-related morbidity and mortality worldwide. METHODS We employed two distinct methodological approaches to estimate the burden of diarrhea due to Shigellae and ETEC among persons ≥ 5 years of age in the WHO regions of South Asia (SEAR) and Africa (AFR). Under method 1, we conducted a systematic review to identify the median proportion of total deaths due to diarrhea and then applied this figure to the number of all-cause deaths that occurred in 2010 among this age group. To estimate the total number of diarrhea deaths attributable to Shigellae and ETEC, we subsequently applied previously published estimates of the median percentage of diarrhea hospitalizations due to Shigellae and ETEC to the estimated number of diarrhea deaths. For method 2, we applied previously published incidence rates to 2010 population figures and estimated the total number of episodes due to Shigellae and ETEC using published estimates of the average proportion of pathogen-positive outpatients from studies of >4 pathogens. We then estimated the number of pathogen-specific deaths by determining the number of hospitalized patients and applying the case-fatality rate. RESULTS By method 1, there were 19,451 deaths due to Shigellae and 42,973 due to ETEC in AFR, and 20,691 due to Shigellae and 45,713 due to ETEC in SEAR in 2010. By method 2, there were 15.0 million ETEC episodes and 30.4 million episodes due to Shigellae in AFR, and 28.7 million episodes due to ETEC and 58.1 million episodes due to Shigellae in SEAR in 2010. We were unable to identify published case-fatality rates for ETEC and thus could only estimate Shigellae-related deaths using method 2, by which there were 5,308 and 10,158 Shigellae-related deaths in AFR and SEAR in 2010, respectively. DISCUSSION Methods 1 and 2 underscore the importance of Shigellae and ETEC as major causes of morbidity and mortality among older children, adolescents, and adults in AFR and SEAR. Understanding the epidemiology of these pathogens is imperative for the development and use of future vaccines and other preventative interventions.
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Affiliation(s)
- Laura M. Lamberti
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, Maryland, United States of America
| | | | - Christa L. Fischer Walker
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, Maryland, United States of America
- * E-mail:
| | - Robert E. Black
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, Maryland, United States of America
| | - David Sack
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, Maryland, United States of America
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Darsley MJ, Chakraborty S, DeNearing B, Sack DA, Feller A, Buchwaldt C, Bourgeois AL, Walker R, Harro CD. The oral, live attenuated enterotoxigenic Escherichia coli vaccine ACE527 reduces the incidence and severity of diarrhea in a human challenge model of diarrheal disease. Clin Vaccine Immunol 2012; 19:1921-31. [PMID: 23035175 PMCID: PMC3535858 DOI: 10.1128/cvi.00364-12] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 09/24/2012] [Indexed: 11/20/2022]
Abstract
An oral, live attenuated, three-strain recombinant bacterial vaccine, ACE527, was demonstrated to generate strong immune responses to colonization factor and toxin antigens of enterotoxigenic Escherichia coli (ETEC) in human volunteers. The vaccine was safe and well tolerated at doses of up to 10(11) CFU, administered in each of two doses given 21 days apart. These observations have now been extended in a phase 2b study with a total of 70 subjects. Fifty-six of these subjects were challenged 28 days after the second dose of vaccine with the highly virulent ETEC strain H10407 to obtain preliminary indicators of efficacy against disease and to support further development of the vaccine for both travelers and infants in countries where ETEC is endemic. The vaccine had a significant impact on intestinal colonization by the challenge strain, as measured by quantitative fecal culture 2 days after challenge, demonstrating the induction of a functional immune response to the CFA/I antigen. The incidence and severity of diarrhea were also reduced in vaccinees as measured by a number of secondary and ad hoc endpoints, although the 27% reduction seen in the primary endpoint, moderate to severe diarrhea, was not statistically significant. Together, these observations support the hypothesis that the ACE527 vaccine has a dual mode of action, targeting both colonization factors and the heat-labile enterotoxin (LT), and suggest that it should be further developed for more advanced trials to evaluate its impact on the burden of ETEC disease in field settings.
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McKenzie R, Porter CK, Cantrell JA, Denearing B, O'Dowd A, Grahek SL, Sincock SA, Woods C, Sebeny P, Sack DA, Tribble DR, Bourgeois AL, Savarino SJ. Volunteer challenge with enterotoxigenic Escherichia coli that express intestinal colonization factor fimbriae CS17 and CS19. J Infect Dis 2011; 204:60-4. [PMID: 21628659 DOI: 10.1093/infdis/jir220] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human challenges with enterotoxigenic Escherichia coli (ETEC) have broadened our understanding of this important enteropathogen. We report findings from the first challenge studies using ETEC-expressing colonization factor fimbria CS17 and CS19. LSN03-016011/A (LT, CS17) elicited a dose-dependent effect, with the upper dose (6 × 10(9) organisms) causing diarrhea in 88% of recipients. WS0115A (LTSTp, CS19) also showed a dose response, with a 44% diarrhea rate at 9 × 10(9) organisms. Both strains elicited homologous antifimbrial and anti-LT antibody seroconversion. These studies establish the relative pathogenicity of ETEC expressing newer class 5 fimbriae and suggest suitability of the LT|CS17-ETEC challenge model for interventional trials.
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Affiliation(s)
- Robin McKenzie
- Department of Medicine, Johns Hopkins University, Johns Hopkins Bayview Medical Center, MD, USA
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Gaston JSH, Inman RD, Ryan ET, Venkatesan MM, Barry EM, Hale TL, Bourgeois AL, Walker RI. Vaccination of children in low-resource countries against Shigella is unlikely to present an undue risk of reactive arthritis. Vaccine 2009; 27:5432-4. [DOI: 10.1016/j.vaccine.2009.06.107] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Accepted: 06/30/2009] [Indexed: 11/16/2022]
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Meraz IM, Jiang ZD, Ericsson CD, Bourgeois AL, Steffen R, Taylor DN, Hernandez N, DuPont HL. Enterotoxigenic Escherichia coli and diffusely adherent E. coli as likely causes of a proportion of pathogen-negative travelers' diarrhea--a PCR-based study. J Travel Med 2008; 15:412-8. [PMID: 19090795 DOI: 10.1111/j.1708-8305.2008.00249.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Enteropathogens cannot be identified in 40% to 50% of subjects with travelers' diarrhea (TD). METHODS We used polymerase chain reaction (PCR) methods to look for the presence of two bacterial causes of diarrhea in a large group of international travelers after failing to detect a pathogen by conventional tests. DNA was isolated from the diarrheal stool and subjected to PCR from 162 subjects from whom we earlier failed to identify a pathogen in a previous study and included 54 from Antigua, Guatemala, 39 from Guadalajara, Mexico, 29 from Kolkata, India, and 40 from Goa, India. Gene products for enterotoxigenic Escherichia coli (ETEC)--LT (heat-labile enterotoxin) and ST (heat-stable enterotoxin)--and diffusely adherent E. coli (DAEC), afa/dr (Afa fimbrial and Dr nonfimbrial family of adhesins), were used. RESULTS At least one gene product was identified in diarrhea stool samples of 47 of 162 (29%) subjects. ETEC virulence genes (LT, ST) were found in 34 (21%) samples studied, with rates of occurrence ranging from 8% in Goa to 39% for the samples from Guatemala (p = 0.0006). A large number of ST-only strains explained the high ETEC rate in Guatemala. DAEC afa/dr family of adhesions was identified in between 8 and 14% of the samples. CONCLUSIONS ETEC and DAEC were implicated in nearly one-third of the subjects initially diagnosed as pathogen negative. Direct PCR results from stools are consistent with the previous assumption that most undiagnosed TD is bacterial in nature and also highlights the potential value that PCR can add to studies designed to evaluate treatment and preventive interventions for TD, including vaccines.
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Affiliation(s)
- Ismail M Meraz
- School of Public Health, University of Texas, Houston, TX 77030, USA
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Frech SA, Dupont HL, Bourgeois AL, McKenzie R, Belkind-Gerson J, Figueroa JF, Okhuysen PC, Guerrero NH, Martinez-Sandoval FG, Meléndez-Romero JH, Jiang ZD, Asturias EJ, Halpern J, Torres OR, Hoffman AS, Villar CP, Kassem RN, Flyer DC, Andersen BH, Kazempour K, Breisch SA, Glenn GM. Use of a patch containing heat-labile toxin from Escherichia coli against travellers' diarrhoea: a phase II, randomised, double-blind, placebo-controlled field trial. Lancet 2008; 371:2019-25. [PMID: 18554712 DOI: 10.1016/s0140-6736(08)60839-9] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Enterotoxigenic Escherichia coli (ETEC) is a major cause of travellers' diarrhoea. We investigated the rate of diarrhoea attacks, safety, and feasibility of a vaccine containing heat-labile enterotoxin (LT) from ETEC delivered to the skin by patch in travellers to Mexico and Guatemala. METHODS In this phase II study, healthy adults (aged 18-64 years) who planned to travel to Mexico or Guatemala and had access to a US regional vaccination centre were eligible. A centralised randomisation code was used for allocation, which was masked to participants and site staff. Primary endpoints were to investigate the field rate of ETEC diarrhoea, and to assess the safety of heat-labile toxins from E coli (LT) delivered via patch. Secondary endpoints included vaccine efficacy against travellers' diarrhoea and ETEC. Participants were vaccinated before travel, with two patches given 2-3 weeks apart. Patches contained either 37.5 mug of LT or placebo. Participants tracked stool output on diary cards in country and provided samples for pathogen identification if diarrhoea occurred. Diarrhoea was graded by the number of loose stools in 24 h: mild (three), moderate (four or five), and severe (at least six). Analysis was per protocol. The trial is registered with ClinicalTrials.gov, number NCT00516659. FINDINGS Recruitment closed after 201 participants were assigned patches. 178 individuals received two vaccinations and travelled and 170 were analysed. 24 (22%) of 111 placebo recipients had diarrhoea, of whom 11 (10%) had ETEC diarrhoea. The vaccine was safe and immunogenic. The 59 LT-patch recipients were protected against moderate-to-severe diarrhoea (protective efficacy [PE] 75%, p=0.0070) and severe diarrhoea (PE 84%, p=0.0332). LT-patch recipients who became ill had shorter episodes of diarrhoea (0.5 days vs 2.1 days, p=0.0006) with fewer loose stools (3.7 vs 10.5, p<0.0001) than placebo. INTERPRETATION Travellers' diarrhoea is a common ailment, with ETEC diarrhoea illness occurring in 10% of cases. The vaccine patch is safe and feasible, with benefits to the rate and severity of travellers' diarrhoea.
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McKenzie R, Venkatesan MM, Wolf MK, Islam D, Grahek S, Jones AM, Bloom A, Taylor DN, Hale TL, Bourgeois AL. Safety and immunogenicity of WRSd1, a live attenuated Shigella dysenteriae type 1 vaccine candidate. Vaccine 2008; 26:3291-6. [DOI: 10.1016/j.vaccine.2008.03.079] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2008] [Revised: 03/26/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
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McKenzie R, Bourgeois AL, Frech SA, Flyer DC, Bloom A, Kazempour K, Glenn GM. Transcutaneous immunization with the heat-labile toxin (LT) of enterotoxigenic Escherichia coli (ETEC): Protective efficacy in a double-blind, placebo-controlled challenge study. Vaccine 2007; 25:3684-91. [PMID: 17313998 DOI: 10.1016/j.vaccine.2007.01.043] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2006] [Revised: 01/03/2007] [Accepted: 01/09/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND An enterotoxigenic Escherichia coli (ETEC) vaccine could reduce diarrhea among children in developing countries and travelers to these countries. The heat-labile toxin (LT) of ETEC is immunogenic but too toxic for oral or nasal vaccines. METHODS In a double-blind, placebo-controlled trial, 59 adults were randomized to receive 50 microg of LT or placebo in a patch applied to alternating arms on days 0, 21, and 42. On day 56, 27 vaccinees and 20 controls were challenged orally with 6x10(8) cfu of LT+/ST+ ETEC. RESULTS 100 and 97% of vaccinees had 4-fold increases in anti-LT IgG and IgA, and 100 and 90% developed IgG- and IgA-antibody-secreting cell responses. The study did not meet the primary endpoint: 82% of vaccinees and 75% of controls had moderate to severe ETEC illness. However, vaccinees with ETEC illness had lower numbers (6.8 versus 9.7, p=0.04) and weights of loose stools (840 g versus 1147 g, p<0.05), a decreased need for intravenous fluids (14% versus 40%, p=0.03) and a delayed onset of diarrhea (30 h versus 22 h, p=0.01). CONCLUSIONS Transcutaneous LT vaccination induced anti-toxin immune responses that did not prevent but mitigated illness following a high-dose challenge with a virulent LT+/ST+ ETEC strain.
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Affiliation(s)
- Robin McKenzie
- Division of Infectious Diseases, Johns Hopkins University, Johns Hopkins Bayview Medical Center, 4940 Eastern Ave., Baltimore, MD 21224, United States.
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Glenn GM, Villar CP, Flyer DC, Bourgeois AL, McKenzie R, Lavker RM, Frech SA. Safety and immunogenicity of an enterotoxigenic Escherichia coli vaccine patch containing heat-labile toxin: use of skin pretreatment to disrupt the stratum corneum. Infect Immun 2007; 75:2163-70. [PMID: 17261601 PMCID: PMC1865773 DOI: 10.1128/iai.01740-06] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcutaneous immunization allows safe delivery of native heat-labile enterotoxin (LT) from Escherichia coli via application of a simple patch. Physical disruption of the stratum corneum can improve the efficiency of delivery. In the current study, the stratum corneum was disrupted using an electrocardiogram prep pad prior to patch application. The effects were quantified using transepidermal water loss (TEWL) and were correlated with the immune responses. Sixty adults received 50 microg of LT from three lots of LT (20 adults per group) administered in a patch on days 0 and 21. The immunizations were well tolerated. There were no differences in the anti-LT immunoglobulin G (IgG) titers between the three LT lots; the seroconversion rate was 100%, and the mean anti-LT IgG titer was 12,185 enzyme-linked immunosorbent assay units (EU) (a 24-fold increase). TEWL measurements obtained at the time of the second immunization were found to correlate with the day 42 individual increases in the anti-LT IgG titer (r = 0.59, P < 0.001). In a comparative assessment of the immune responses, sera after an LT+ ST+ (E2447A) oral ETEC challenge, which induced moderate to severe diarrhea in 81% of the recipients, had anti-LT IgG titers of 3,245 EU (a 10.8-fold increase). Similarly, the anti-LT IgG titer after administration of an oral cholera toxin B subunit-containing cholera vaccine, which cross-reacts with LT and protects against LT and LT/heat-stable toxin ETEC disease in the field, was 6,741 EU (a 3.3-fold increase). This study confirmed that a well-tolerated regimen for stratum corneum disruption before vaccine patch application results in robust immunity comparable to natural immunity and vaccine-induced immunity and that the magnitude of stratum corneum disruption correlates with the immune response.
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Affiliation(s)
- Gregory M Glenn
- IOMAI Corporation, 20 Firstfield Road, Gaithersburg, MD 20878, USA.
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Bölin I, Wiklund G, Qadri F, Torres O, Bourgeois AL, Savarino S, Svennerholm AM. Enterotoxigenic Escherichia coli with STh and STp genotypes is associated with diarrhea both in children in areas of endemicity and in travelers. J Clin Microbiol 2006; 44:3872-7. [PMID: 16943355 PMCID: PMC1698338 DOI: 10.1128/jcm.00790-06] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea among children in developing countries and in travelers to areas of ETEC endemicity. ETEC strains isolated from humans may produce a heat-labile enterotoxin (LT) and two types of the heat-stable enterotoxin STa, called STh and STp, encoded by the estA gene. Two commonly used assay methods for the detection of STa, the infant mouse assay or different enzyme-linked immunosorbent assays, are unable to distinguish between the two subtypes of ST. Different genotypic methods, such as DNA probes or PCR assays, may, however, allow such discrimination. Using gene probes, it has recently been reported that ETEC strains producing STp as the only enterotoxin are not associated with diarrhea. In this study, we have used highly specific PCR methods, including newly designed primers for STh together with previously described STp primers, to compare the relative distribution of STh and STp in ETEC isolated from children with diarrhea in three different geographically distinct areas, i.e., Bangladesh, Egypt, and Guatemala, and from travelers to Mexico and Guatemala. It was found that ETEC strains producing STp were as commonly isolated from cases of diarrhea as strains producing STh both in Egypt and Guatemala, whereas STp strains were considerably less common in Bangladesh. No difference was found in the relative distribution of STh and STp in ETEC strains isolated from travelers with diarrhea and from asymptomatic carriers. Irrespective of ST genotype, the disease symptoms were also similar in both children and travelers.
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Affiliation(s)
- Ingrid Bölin
- Department of Microbiology and Immunology, and Göteborg Vaccine Research Institute (GUVAX), Göteborg University, Göteborg, Sweden.
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Taylor DN, Bourgeois AL, Ericsson CD, Steffen R, Jiang ZD, Halpern J, Haake R, Dupont HL. A randomized, double-blind, multicenter study of rifaximin compared with placebo and with ciprofloxacin in the treatment of travelers' diarrhea. Am J Trop Med Hyg 2006; 74:1060-6. [PMID: 16760520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
Rifaximin was compared with placebo and ciprofloxacin for treatment of travelers' diarrhea in a randomized, double-blind clinical trial. Adult travelers (N = 399) consulting travel clinics in Mexico, Guatemala, and India were randomized to receive rifaximin 200 mg three times a day, ciprofloxacin (500 mg two times a day and placebo once a day), or placebo three times a day for 3 days. Patients recorded in daily diaries the time and consistency of each stool and documented symptoms for 5 days after treatment. Stool samples were collected for microbiologic evaluations before and after treatment. The median time to last unformed stool (TLUS) in the rifaximin group (32.0 hours) was less than one half that in the placebo group (65.5 hours; P = 0.001; risk ratio 1.6; 95% confidence interval 1.2, 2.2; primary efficacy endpoint). The median TLUS in the ciprofloxacin group was 28.8 hours (P = 0.0003 versus placebo; P = 0.35 versus rifaximin). Rifaximin was less effective than ciprofloxacin for invasive intestinal bacterial pathogens. Oral rifaximin is a safe and effective treatment of travelers' diarrhea caused by noninvasive pathogens.
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Affiliation(s)
- David N Taylor
- Salix Pharmaceuticals, Inc., Morrisville, North Carolina, USA.
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