1
|
Ng'ombe H, Bosomprah S, Phiri B, Muchimba M, Liswaniso F, Chibuye M, Luchen CC, Chibesa K, Musukuma-Chifulo K, Mwape K, Tigere S, Silwamba S, Sinkala A, Simuyandi M, Mbewe N, Kapaya F, Cunningham AF, Chilengi R, Sack D, Chisenga CC. Comparative analysis of cholera serum vibriocidal antibodies from Convalescent and vaccinated adults in Zambia. Vaccine 2024:S0264-410X(24)00587-5. [PMID: 38760271 DOI: 10.1016/j.vaccine.2024.05.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 05/10/2024] [Accepted: 05/14/2024] [Indexed: 05/19/2024]
Abstract
Cholera is responsible for 1.3 to 4.0 million cholera cases globally and poses a significant threat, with Zambia reporting 17,169 cases as of 4th February 2024. Recognizing the crucial link between natural cholera infections and vaccine protection, this study aimed to assess immune responses post cholera infection and vaccination. This was a comparative study consisting of 50 participants enrolled during a cholera outbreak in Zambia's Eastern Province and an additional 56 participants who received oral cholera vaccinations in Zambia's Central Province. Vibriocidal antibodies were plotted as geometric mean titres in the naturally infected and vaccinated individuals. A significant difference (p < 0.047) emerged when comparing naturally infected to fully vaccinated individuals (2 doses) on day 28 against V. cholerae Ogawa. Those who received two doses of the oral cholera vaccine had higher antibody titres than those who were naturally infected. Notably, the lowest titres occurred between 0-9 days post onset, contrasting with peak responses at 10-19 days. This study addresses a critical knowledge gap in understanding cholera immunity dynamics, emphasizing the potential superiority of vaccination-induced immune responses. We recommend post infection vaccination after 40 days for sustained immunity and prolonged protection, especially in cholera hotspots.
Collapse
Affiliation(s)
- Harriet Ng'ombe
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Samuel Bosomprah
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia; Department of Biostatistics, School of Public Health, University of Ghana, Accra, Ghana.
| | - Bernard Phiri
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Mutinta Muchimba
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Fraser Liswaniso
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Mwelwa Chibuye
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Charlie Chaluma Luchen
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Kennedy Chibesa
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Kalo Musukuma-Chifulo
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Kapambwe Mwape
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Sekayi Tigere
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Suwilanji Silwamba
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Annel Sinkala
- Ministry of Health, Levy Mwanawasa University Teaching Hospital, Chainama, Off Great East, P.0 Box 310084, Lusaka, Zambia
| | - Michelo Simuyandi
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| | - Nyuma Mbewe
- Zambia National Public Health Institute, Stand 1186, Corner of Chaholi & Addis Ababa Roads Rhodes Park, Lusaka, Zambia
| | - Fred Kapaya
- Zambia National Public Health Institute, Stand 1186, Corner of Chaholi & Addis Ababa Roads Rhodes Park, Lusaka, Zambia
| | - Adam F Cunningham
- Institute of Immunology and Immunotherapy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom
| | - Roma Chilengi
- Zambia National Public Health Institute, Stand 1186, Corner of Chaholi & Addis Ababa Roads Rhodes Park, Lusaka, Zambia
| | - David Sack
- John Hopkins University, 615 N Wolfe St, Baltimore, United States of America
| | - Caroline Cleopatra Chisenga
- Centre for Infectious Disease Research in Zambia, Corner of Lukasu and Danny Pule Roads, Mass Media, Lusaka, Zambia
| |
Collapse
|
2
|
Kaisar MH, Kelly M, Kamruzzaman M, Bhuiyan TR, Chowdhury F, Khan AI, LaRocque RC, Calderwood SB, Harris JB, Charles RC, Čížová A, Mečárová J, Korcová J, Bystrický S, Kováč P, Xu P, Qadri F, Ryan ET. Comparison of O-specific polysaccharide responses in patients following infection with Vibrio cholerae O139 versus vaccination with a bivalent (O1/O139) oral killed cholera vaccine in Bangladesh. mSphere 2023; 8:e0025523. [PMID: 37646517 PMCID: PMC10597347 DOI: 10.1128/msphere.00255-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 07/05/2023] [Indexed: 09/01/2023] Open
Abstract
Cholera caused by Vibrio cholerae O139 emerged in the early 1990s and spread rapidly to 11 Asian countries before receding for unclear reasons. Protection against cholera is serogroup-specific, which is defined by the O-specific polysaccharide (OSP) component of lipopolysaccharide (LPS). V. cholerae O139 also expresses the OSP-capsule. We, therefore, assessed antibody responses targeting V. cholerae O139 OSP, LPS, capsule, and vibriocidal responses in patients in Bangladesh with cholera caused by V. cholerae O139. We compared these responses to those of age-gender-blood group-matched recipients of the bivalent oral cholera vaccine (OCV O1/O139). We found prominent OSP, LPS, and vibriocidal responses in patients, with a high correlation between these responses. OSP responses primarily targeted the terminal tetrasaccharide of OSP. Vaccinees developed OSP, LPS, and vibriocidal antibody responses, but of significantly lower magnitude and responder frequency (RF) than matched patients. We separately analyzed responses in pediatric vaccinees born after V. cholerae O139 had receded in Bangladesh. We found that OSP responses were boosted in children who had previously received a single dose of bivalent OCV 3 yr previously but not in vaccinated immunologically naïve children. Our results suggest that OSP-specific responses occur during cholera caused by V. cholerae O139 despite the presence of capsules, that vaccination with bivalent OCV is poorly immunogenic in the short term in immunologically naïve individuals, but that OSP-specific immune responses can be primed by previous exposure, although whether such responses can protect against O139 cholera is uncertain. IMPORTANCE Cholera is a severe dehydrating illness in humans caused by Vibrio cholerae serogroups O1 or O139. Protection against cholera is serogroup-specific, which is defined by the O-specific polysaccharide (OSP) of V. cholerae LPS. Yet, little is known about immunity to O139 OSP. In this study, we assessed immune responses targeting OSP in patients from an endemic region with cholera caused by V. cholerae O139. We compared these responses to those of the age-gender-blood group-matched recipients of the bivalent oral cholera vaccine. Our results suggest that OSP-specific responses occur during cholera caused by V. cholerae O139 and that the OSP responses primarily target the terminal tetrasaccharide of OSP. Our results further suggest that vaccination with the bivalent vaccine is poorly immunogenic in the short term for inducing O139-specific OSP responses in immunologically naïve individuals, but OSP-specific immune responses can be primed by previous exposure or vaccination.
Collapse
Affiliation(s)
- M. Hasanul Kaisar
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Meagan Kelly
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Mohammad Kamruzzaman
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Taufiqur R. Bhuiyan
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Fahima Chowdhury
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Ashraful Islam Khan
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Regina C. LaRocque
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Stephen B. Calderwood
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Jason B. Harris
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Division of Global Health, MassGeneral Hospital for Children, Boston, Massachusetts, USA
| | - Richelle C. Charles
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Alžbeta Čížová
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Mečárová
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Korcová
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
- Department of Chemical Theory of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovakia
| | - Slavomír Bystrický
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Pavol Kováč
- Laboratory of Bioorganic Chemistry (LBC), National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, Maryland, USA
| | - Peng Xu
- Laboratory of Bioorganic Chemistry (LBC), National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK), National Institutes of Health, Bethesda, Maryland, USA
| | - Firdausi Qadri
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Edward T. Ryan
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| |
Collapse
|
3
|
Jones FK, Bhuiyan TR, Muise RE, Khan AI, Slater DM, Hutt Vater KR, Chowdhury F, Kelly M, Xu P, Kováč P, Biswas R, Kamruzzaman M, Ryan ET, Calderwood SB, LaRocque RC, Lessler J, Charles RC, Leung DT, Qadri F, Harris JB, Azman AS. Identifying Recent Cholera Infections Using a Multiplex Bead Serological Assay. mBio 2022; 13:e0190022. [PMID: 36286520 PMCID: PMC9765614 DOI: 10.1128/mbio.01900-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 08/31/2022] [Indexed: 11/20/2022] Open
Abstract
Estimates of incidence based on medically attended cholera can be severely biased. Vibrio cholerae O1 leaves a lasting antibody signal and recent advances showed that these can be used to estimate infection incidence rates from cross-sectional serologic data. Current laboratory methods are resource intensive and challenging to standardize across laboratories. A multiplex bead assay (MBA) could efficiently expand the breadth of measured antibody responses and improve seroincidence accuracy. We tested 305 serum samples from confirmed cholera cases (4 to 1083 d postinfection) and uninfected contacts in Bangladesh using an MBA (IgG/IgA/IgM for 7 Vibrio cholerae O1-specific antigens) as well as traditional vibriocidal and enzyme-linked immunosorbent assays (2 antigens, IgG, and IgA). While postinfection vibriocidal responses were larger than other markers, several MBA-measured antibodies demonstrated robust responses with similar half-lives. Random forest models combining all MBA antibody measures allowed for accurate identification of recent cholera infections (e.g., past 200 days) including a cross-validated area under the curve (cvAUC200) of 92%, with simpler 3 IgG antibody models having similar accuracy. Across infection windows between 45 and 300 days, the accuracy of models trained on MBA measurements was non-inferior to models based on traditional assays. Our results illustrated a scalable cholera serosurveillance tool that can be incorporated into multipathogen serosurveillance platforms. IMPORTANCE Reliable estimates of cholera incidence are challenged by poor clinical surveillance and health-seeking behavior biases. We showed that cross-sectional serologic profiles measured with a high-throughput multiplex bead assay can lead to accurate identification of those infected with pandemic Vibrio cholerae O1, thus allowing for estimates of seroincidence. This provides a new avenue for understanding the epidemiology of cholera, identifying priority areas for cholera prevention/control investments, and tracking progress in the global fight against this ancient disease.
Collapse
Affiliation(s)
- Forrest K. Jones
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Taufiqur R. Bhuiyan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Rachel E. Muise
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Ashraful I. Khan
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Damien M. Slater
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Kian Robert Hutt Vater
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Fahima Chowdhury
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Meagan Kelly
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Peng Xu
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Pavol Kováč
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rajib Biswas
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Mohammad Kamruzzaman
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Edward T. Ryan
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Stephen B. Calderwood
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Regina C. LaRocque
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Justin Lessler
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, North Carolina, USA
- University of North Carolina Population Center, University of North Carolina Gillings School of Global Public Health, Chapel Hill, North Carolina, USA
| | - Richelle C. Charles
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Daniel T. Leung
- Division of Infectious Diseases, University of Utah School of Medicine, Salt Lake City, Utah, USA
- Division of Microbiology and Immunology, University of Utah School of Medicine, Salt Lake City, Utah, USA
| | - Firdausi Qadri
- Infectious Diseases Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Jason B. Harris
- Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
| | - Andrew S. Azman
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Institute of Global Health, University of Geneva, Geneva, Switzerland
| |
Collapse
|
4
|
Sit B, Fakoya B, Waldor MK. Emerging Concepts in Cholera Vaccine Design. Annu Rev Microbiol 2022; 76:681-702. [PMID: 35759873 DOI: 10.1146/annurev-micro-041320-033201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cholera is a severe diarrheal disease caused by the bacterium Vibrio cholerae and constitutes a significant public health threat in many areas of the world. V. cholerae infection elicits potent and long-lasting immunity, and efforts to develop cholera vaccines have been ongoing for more than a century. Currently available inactivated two-dose oral cholera vaccines are increasingly deployed to both prevent and actively curb cholera outbreaks, and they are key components of the global effort to eradicate cholera. However, these killed whole-cell vaccines have several limitations, and a variety of new oral and nonoral cholera vaccine platforms have recently been developed. Here, we review emerging concepts in cholera vaccine design and implementation that have been driven by insights from human and animal studies. As a prototypical vaccine-preventable disease, cholera continues to be an excellent target for the development and application of cutting-edge technologies and platforms that may transform vaccinology. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Brandon Sit
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA; .,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Bolutife Fakoya
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA; .,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew K Waldor
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, Massachusetts, USA; .,Department of Microbiology, Harvard Medical School, Boston, Massachusetts, USA.,Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Massachusetts, USA.,Howard Hughes Medical Institute, Bethesda, Maryland, USA
| |
Collapse
|
5
|
Long-Term Kinetics of Serological Antibodies against Vibrio cholerae Following a Clinical Cholera Case: A Systematic Review and Meta-Analysis. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19127141. [PMID: 35742404 PMCID: PMC9223532 DOI: 10.3390/ijerph19127141] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 11/16/2022]
Abstract
Background: Approximately 2.9 million people worldwide suffer from cholera each year, many of whom are destitute. However, understanding of immunity against cholera is still limited. Several studies have reported the duration of antibodies following cholera; however, systematic reviews including a quantitative synthesis are lacking. Objective: To meta-analyze cohort studies that have evaluated vibriocidal, cholera toxin B subunit (CTB), and lipopolysaccharide (LPS) antibody levels following a clinical cholera case. Methods: Design: Systematic review and meta-analysis. We searched PubMed and Web of science for studies assessing antibodies against Vibrio cholerae in cohorts of patients with clinical cholera. Two authors independently extracted data and assessed the quality of included studies. Random effects models were used to pool antibody titers in adults and older children (aged ≥ 6 years). In sensitivity analysis, studies reporting data on young children (2–5 years) were included. Results: Nine studies met our inclusion criteria for systematic review and seven for meta-analysis. The pooled mean of vibriocidal antibody titers in adults and older children (aged ≥ 6 years) was 123 on day 2 post-symptom onset, which sharply increased on day 7 (pooled mean = 6956) and gradually waned to 2247 on day 30, 578 on day 90, and 177 on day 360. Anti-CTB IgA antibodies also peaked on day 7 (pooled mean = 49), followed by a rapid decrease on day 30 (pooled mean = 21), and further declined on day 90 (pooled mean = 10), after which it plateaued from day 180 (pooled mean = 8) to 360 (pooled mean = 6). Similarly, anti-CTB IgG antibodies peaked in early convalescence between days 7 (pooled mean = 65) and 30 (pooled mean = 69), then gradually waned on days 90 (pooled mean = 42) and 180 (pooled mean = 30) and returned to baseline on day 360 (pooled mean = 24). Anti-LPS IgA antibodies peaked on day 7 (pooled mean = 124), gradually declined on day 30 (pooled mean = 44), which persisted until day 360 (pooled mean = 10). Anti LPS IgG antibodies peaked on day 7 (pooled mean = 94). Thereafter, they decreased on day 30 (pooled mean = 85), and dropped further on days 90 (pooled mean = 51) and 180 (pooled mean = 47), and returned to baseline on day 360 (pooled mean = 32). Sensitivity analysis including data from young children (aged 2–5 years) showed very similar findings as in the primary analysis. Conclusions: This study confirms that serological antibody (vibriocidal, CTB, and LPS) titers return to baseline levels within 1 year following clinical cholera, i.e., before the protective immunity against subsequent cholera wanes. However, this decay should not be interpreted as waning immunity because immunity conferred by cholera against subsequent disease lasts 3–10 years. Our study provides evidence for surveillance strategies and future research on vaccines and also demonstrates the need for further studies to improve our understanding of immunity against cholera.
Collapse
|