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Abstract
The rapid spread of the 7 th cholera pandemic over Asia in the 1960s led to several large field studies that revealed that the traditional injectable cholera vaccines had poor efficacy, usually less than 50% for only 3-6 months, which led WHO in the 1970s to stop recommending cholera vaccination. At the same time, it stimulated research that has led to the development of the effective orally administered cholera vaccines (OCVs) that today are a cornerstone in WHO´s strategy for "Ending Cholera - A Global Roadmap to 2030". The first effective OCV, Dukoral™, containing a mixture of inactivated Vibrio cholerae bacteria and cholera toxin B subunit, was licenced in 1993 and is together with two similar inactivated whole-cell OCVs, Shanchol™ and Euvichol™/Euvichol-Plus™, the OCVs currently prequalified and recommended by WHO. This brief review is a personalized account of the "modern history" of the development of these now universally recognized effective tools for the control and ultimate elimination of cholera, and of the pivotal role of icddr,b and Bangladesh for this development.
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AbdelAllah NH, Gaber Y, AbdelGhani S, Rashed ME, Azmy AF. Chitosan and alginate salt as biomaterials are potential natural adjuvants for killed cholera vaccine. J Biomed Mater Res A 2021; 109:2462-2470. [PMID: 34117696 DOI: 10.1002/jbm.a.37240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [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: 03/05/2021] [Revised: 05/16/2021] [Accepted: 05/18/2021] [Indexed: 12/30/2022]
Abstract
Chitosan and alginate salts are natural biopolymers that have gained recent attention in the biomedical sectors. Their properties allow them to become potential candidates as safe, cheap, and effective vaccine adjuvants. The present study aimed to enhance the immunogenic response of a current injectable killed cholera vaccine (KCV) using chitosan and alginate salt as natural adjuvants against alum. We tested KCV adjuvanted with alum, chitosan, and sodium alginate in mice. Mice were immunized intraperitoneally with KCV adjuvanted with alum, chitosan, or alginate salt and compared with a control unadjuvanted immunized group. Humoral, cellular, and functional immune responses were evaluated in all groups. The addition of adjuvants, particularly natural adjuvants, to KCV significantly improved the immune response as demonstrated by specific antibody increase, strong proliferation effects, and high protection rate against different challenge doses of cholera strains. Our findings demonstrate that chitosan and alginate salt are superior adjuvants for boosting the KCV immune response and highlights the requirement for further vaccine development.
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Affiliation(s)
- Nourhan H AbdelAllah
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt.,Viral Control Unit, Egyptian Drug Authority (EDA), Cairo, Egypt
| | - Yasser Gaber
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt.,Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, Mutah University, Al-karak, Jordan
| | - Sameh AbdelGhani
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt.,Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA
| | - Mohamed E Rashed
- Microbiology Department, Egyptian Drug Authority (EDA), Cairo, Egypt
| | - Ahmed F Azmy
- Department of Microbiology and Immunology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
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3
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Lopez AL, Deen J, Azman AS, Luquero FJ, Kanungo S, Dutta S, von Seidlein L, Sack DA. Immunogenicity and Protection From a Single Dose of Internationally Available Killed Oral Cholera Vaccine: A Systematic Review and Metaanalysis. Clin Infect Dis 2018; 66:1960-1971. [PMID: 29177437 PMCID: PMC5982790 DOI: 10.1093/cid/cix1039] [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] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/19/2017] [Indexed: 12/16/2022] Open
Abstract
In addition to improved water supply and sanitation, the 2-dose killed oral cholera vaccine (OCV) is an important tool for the prevention and control of cholera. We aimed to document the immunogenicity and protection (efficacy and effectiveness) conferred by a single OCV dose against cholera. The metaanalysis showed that an estimated 73% and 77% of individuals seroconverted to the Ogawa and Inaba serotypes, respectively, after an OCV first dose. The estimates of single-dose vaccine protection from available studies are 87% at 2 months decreasing to 33% at 2 years. Current immunologic and clinical data suggest that protection conferred by a single dose of killed OCV may be sufficient to reduce short-term risk in outbreaks or other high-risk settings, which may be especially useful when vaccine supply is limited. However, until more data suggest otherwise, a second dose should be given as soon as circumstances allow to ensure robust protection.
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Affiliation(s)
- Anna Lena Lopez
- Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines, Manila
- Delivering Oral Vaccine Effectively, Department of International Health, Johns Hopkins University, Baltimore, Maryland
| | - Jacqueline Deen
- Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines, Manila
- Delivering Oral Vaccine Effectively, Department of International Health, Johns Hopkins University, Baltimore, Maryland
| | - Andrew S Azman
- Department of Epidemiology, Johns Hopkins University, Baltimore, Maryland
| | | | - Suman Kanungo
- National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, West Bengal, India
| | - Shanta Dutta
- National Institute of Cholera and Enteric Diseases, Beliaghata, Kolkata, West Bengal, India
| | - Lorenz von Seidlein
- Delivering Oral Vaccine Effectively, Department of International Health, Johns Hopkins University, Baltimore, Maryland
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - David A Sack
- Delivering Oral Vaccine Effectively, Department of International Health, Johns Hopkins University, Baltimore, Maryland
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Yu HJ, Cha DSR, Shin DH, Nair GB, Kim EJ, Kim DW. Design and Construction of Vibrio cholerae Strains That Harbor Various CTX Prophage Arrays. Front Microbiol 2018; 9:339. [PMID: 29563899 PMCID: PMC5846015 DOI: 10.3389/fmicb.2018.00339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [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: 09/25/2017] [Accepted: 02/12/2018] [Indexed: 11/21/2022] Open
Abstract
Toxigenic Vibrio cholerae strains arise upon infection and integration of the lysogenic cholera toxin phage, the CTX phage, into bacterial chromosomes. The V. cholerae serogroup O1 strains identified to date can be broadly categorized into three main groups: the classical biotype strains, which harbor CTX-cla; the prototype El Tor strains (Wave 1 strains), which harbor CTX-1; and the atypical El Tor strains, which harbor CTX-2 (Wave 2 strains) or CTX-3~6 (Wave 3 strains). The efficiencies of replication and transmission of CTX phages are similar, suggesting the possibility of existence of more diverse bacterial strains harboring various CTX phages and their arrays in nature. In this study, a set of V. cholerae strains was constructed by the chromosomal integration of CTX phages into strains that already harbored CTX phages or those that did not harbor any CTX phage or RS1 element. Strains containing repeats of the same kind of CTX phage, strains containing the same kind of CTX phage in each chromosome, strains containing alternative CTX phages in one chromosome, or containing different CTX phages in each chromosome have been constructed. Thus, strains with any CTX array can be designed and constructed. Moreover, the strains described in this study contained the toxT-139F allele, which enhances the expression of TcpA and cholera toxin. These characteristics are considered to be important for cholera vaccine development. Once their capacity to provoke immunity in human against V. cholerae infection is evaluated, some of the generated strains could be developed further to yield cholera vaccine strains.
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Affiliation(s)
- Hyun J Yu
- Department of Pharmacy, College of Pharmacy, Hanyang University, Ansan, South Korea.,Institute of Pharmacological Research, Hanyang University, Ansan, South Korea
| | - Da S R Cha
- Department of Pharmacy, College of Pharmacy, Hanyang University, Ansan, South Korea.,Institute of Pharmacological Research, Hanyang University, Ansan, South Korea
| | - Dong-Hun Shin
- Department of Pharmacy, College of Pharmacy, Hanyang University, Ansan, South Korea.,Institute of Pharmacological Research, Hanyang University, Ansan, South Korea
| | - Gopinath B Nair
- South East Asia Regional Office, World Health Organization, New Delhi, India
| | - Eun J Kim
- Department of Pharmacy, College of Pharmacy, Hanyang University, Ansan, South Korea.,Institute of Pharmacological Research, Hanyang University, Ansan, South Korea
| | - Dong W Kim
- Department of Pharmacy, College of Pharmacy, Hanyang University, Ansan, South Korea.,Institute of Pharmacological Research, Hanyang University, Ansan, South Korea
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Debes AK, Ali M, Azman AS, Yunus M, Sack DA. Cholera cases cluster in time and space in Matlab, Bangladesh: implications for targeted preventive interventions. Int J Epidemiol 2018; 45:2134-2139. [PMID: 27789673 DOI: 10.1093/ije/dyw267] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2016] [Indexed: 11/12/2022] Open
Abstract
Background : Cholera remains a serious public health threat in Asia, Africa and in parts of the Americas. Three World health Organization (WHO) pre-qualified oral cholera vaccines are now available but their supply is limited, so current supplies must be administered strategically. This requires an improved understanding of disease transmission and control strategies. Methods : We used demographics and disease surveillance data collected from 1991 to 2000 in Matlab, Bangladesh, to estimate the spatial and temporal extent of the zone of increased risk around cholera cases. Specifically, we compare the cholera incidence among individuals living close to cholera cases with that among individuals living close to those without medically-attended cholera in this rural endemic setting. Results : Those living within 50 m of a confirmed cholera case had 36 times (95% confidence interval: 23-56) the risk of becoming a cholera case in the first 3 days (after case presentation) compared with risk elsewhere in the community. The relative risk gradually declined in space and time, but remained significantly high up to 450 me away within 3 days of case presentation, and up to 150 m away within 23 days from the date of presentation of the case. Conclusion : These findings suggest that, if conducted rapidly, vaccinating individuals living close to a case (ring vaccination) could be an efficient and effective strategy to target vaccine to a high-risk population in an endemic setting.
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Affiliation(s)
- Amanda K Debes
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Mohammad Ali
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Andrew S Azman
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Mohammad Yunus
- International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Dhaka, Bangladesh
| | - David A Sack
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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Sim JR, Kang SS, Lee D, Yun CH, Han SH. Killed Whole-Cell Oral Cholera Vaccine Induces CCL20 Secretion by Human Intestinal Epithelial Cells in the Presence of the Short-Chain Fatty Acid, Butyrate. Front Immunol 2018; 9:55. [PMID: 29434590 PMCID: PMC5796904 DOI: 10.3389/fimmu.2018.00055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 01/09/2018] [Indexed: 01/09/2023] Open
Abstract
Short-chain fatty acids (SCFAs), such as acetate, butyrate, and propionate, modulate immune responses in the gut. However, the effect of SCFAs on mucosal vaccine-induced immune cell migration is poorly understood. Here, we investigated whether SCFAs modulate chemokine expression induced by the killed whole-cell oral cholera vaccine, Shanchol™, in human intestinal epithelial cells. Shanchol™ induced expression of CCL2, CCL5, CCL20, and CXCL10 at the mRNA level, but not at the protein level. Interestingly, CCL20 secretion was substantially increased by co-stimulation with Shanchol™ and butyrate, while neither acetate nor propionate showed such effect. Enhanced CCL20 secretion was associated with GPR109A activation, and histone deacetylase (HDAC) inhibition. In addition, co-treatment with Shanchol™ and butyrate synergistically increased the secretion of adenosine triphosphate (ATP). Moreover, CCL20 secretion was decreased by inhibiting the extracellular ATP receptor P2X7. However, neither inflammasomes nor caspases were involved in CCL20 production. The culture supernatant of cells treated with Shanchol™ and butyrate augmented human immature dendritic cell migration. Collectively, these results suggest that butyrate enhances Shanchol™-induced CCL20 production in human intestinal epithelial cells via HDAC inhibition and ATP-P2X7 signaling by activating GPR109A. These effects potentially enhance the mucosal immune responses in the gut induced by this oral cholera vaccine.
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Affiliation(s)
- Ju-Ri Sim
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, South Korea
| | - Seok-Seong Kang
- Department of Food Science and Biotechnology, Dongguk University Seoul, Goyang, South Korea
| | - Daesang Lee
- The 5th R&D Institute, Agency for Defense Development, Daejeon, South Korea
| | - Cheol-Heui Yun
- Department of Agricultural Biotechnology and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Seung Hyun Han
- Department of Oral Microbiology and Immunology, DRI, and BK21 Plus Program, School of Dentistry, Seoul National University, Seoul, South Korea
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Sow SO, Tapia MD, Chen WH, Haidara FC, Kotloff KL, Pasetti MF, Blackwelder WC, Traoré A, Tamboura B, Doumbia M, Diallo F, Coulibaly F, Onwuchekwa U, Kodio M, Tennant SM, Reymann M, Lam DF, Gurwith M, Lock M, Yonker T, Smith J, Simon JK, Levine MM. Randomized, Placebo-Controlled, Double-Blind Phase 2 Trial Comparing the Reactogenicity and Immunogenicity of a Single Standard Dose to Those of a High Dose of CVD 103-HgR Live Attenuated Oral Cholera Vaccine, with Shanchol Inactivated Oral Vaccine as an Open-Label Immunologic Comparator. Clin Vaccine Immunol 2017; 24:e00265-17. [PMID: 29021299 DOI: 10.1128/CVI.00265-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/02/2017] [Indexed: 12/22/2022]
Abstract
Reactive immunization with a single-dose cholera vaccine that could rapidly (within days) protect immunologically naive individuals during virgin soil epidemics, when cholera reaches immunologically naive populations that have not experienced cholera for decades, would facilitate cholera control. One dose of attenuated Vibrio cholerae O1 classical Inaba vaccine CVD 103-HgR (Vaxchora) containing ≥2 × 108 CFU induces vibriocidal antibody seroconversion (a correlate of protection) in >90% of U.S. adults. A previous CVD 103-HgR commercial formulation required ≥2 × 109 CFU to elicit high levels of seroconversion in populations in developing countries. We compared the vibriocidal responses of Malians (individuals 18 to 45 years old) randomized to ingest a single ≥2 × 108-CFU standard dose (n = 50) or a ≥2 × 109-CFU high dose (n = 50) of PaxVax CVD 103-HgR with buffer or two doses (n = 50) of Shanchol inactivated cholera vaccine (the immunologic comparator). To maintain blinding, participants were dosed twice 2 weeks apart; CVD 103-HgR recipients ingested placebo 2 weeks before or after ingesting vaccine. Seroconversion (a ≥4-fold vibriocidal titer rise) between the baseline and 14 days after CVD 103-HgR ingestion and following the first and second doses of Shanchol were the main outcomes measured. By day 14 postvaccination, the rates of seroconversion after ingestion of a single standard dose and a high dose of CVD 103-HgR were 71.7% (33/46 participants) and 83.3% (40/48 participants), respectively. The rate of seroconversion following the first dose of Shanchol, 56.0% (28/50 participants), was significantly lower than that following the high dose of CVD 103-HgR (P = 0.003). The vibriocidal geometric mean titer (GMT) of the high dose of CVD 103-HgR exceeded the GMT of the standard dose at day 14 (214 versus 95, P = 0.045) and was ∼2-fold higher than the GMT on day 7 and day 14 following the first Shanchol dose (P > 0.05). High-dose CVD 103-HgR is recommended for accelerated evaluation in developing countries to assess its efficacy and practicality in field situations. (This study has been registered at ClinicalTrials.gov under registration no. NCT02145377.)
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Capeding MRZ, Gonzales MLAM, Dhingra MS, D'Cor NA, Midde VJ, Patnaik BN, Thollot Y, Desauziers E. Safety and immunogenicity of the killed bivalent (O1 and O139) whole-cell cholera vaccine in the Philippines. Hum Vaccin Immunother 2017; 13:2232-2239. [PMID: 28910563 PMCID: PMC5975480 DOI: 10.1080/21645515.2017.1342908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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: 12/03/2016] [Revised: 05/30/2017] [Accepted: 06/20/2017] [Indexed: 10/25/2022] Open
Abstract
The killed bivalent (O1 and O139) whole cell oral cholera vaccine (OCV) (Shanchol™) was first licensed in India in 2009 and World Health Organization pre-qualified in 2011. We assessed the safety and immunogenicity of this OCV in the Philippines. This was a phase IV, single-arm, descriptive, open-label study. We recruited 336 participants from 2 centers: 112 participants in each age group (1-4, 5-14 and ≥ 15 years). Participants received 2 OCV doses 14 d apart. Safety was monitored throughout the trial. Blood samples were collected at baseline (pre-vaccination) and 14 d after each dose. Serum vibriocidal antibody titers to V. cholerae O1 (El Tor Inaba and El Tor Ogawa) and O139 strains were assessed, with seroconversion defined as ≥ 4-fold increase from baseline in titers. No immediate unsolicited systemic adverse events/reactions were observed. Unsolicited systemic adverse events were mostly grade 1 intensity. One serious adverse event occurred after the first dose, but was unrelated to vaccination. High seroconversion rates (range 69-92%) were achieved against the O1 serotypes with a trend toward higher rates in the 1-4 y (86-92%) and 5-14 y (86-88%) age groups than the ≥ 15 y age group (69-83%). Lower seroconversion rates were achieved against the O139 serotype (35-70%), particularly in those aged ≥ 15 y (35-42%). The 2-dose regimen of the killed bivalent whole cell OCV was well-tolerated in this study conducted in the Philippines, a cholera-endemic country. Robust immune responses were observed even after a single-dose.
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Affiliation(s)
| | | | | | | | - Venkat Jayanth Midde
- Shantha Biotechnics Private Limited (A Sanofi Company), Hyderabad, Telangana, India
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Desai SN, Pezzoli L, Alberti KP, Martin S, Costa A, Perea W, Legros D. Achievements and challenges for the use of killed oral cholera vaccines in the global stockpile era. Hum Vaccin Immunother 2017; 13:579-587. [PMID: 27813703 PMCID: PMC5360144 DOI: 10.1080/21645515.2016.1245250] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [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: 05/02/2016] [Revised: 09/20/2016] [Accepted: 10/01/2016] [Indexed: 12/13/2022] Open
Abstract
Cholera remains an important but neglected public health threat, affecting the health of the poorest populations and imposing substantial costs on public health systems. Cholera can be eliminated where access to clean water, sanitation, and satisfactory hygiene practices are sustained, but major improvements in infrastructure continue to be a distant goal. New developments and trends of cholera disease burden, the creation of affordable oral cholera vaccines (OCVs) for use in developing countries, as well as recent evidence of vaccination impact has created an increased demand for cholera vaccines. The global OCV stockpile was established in 2013 and with support from Gavi, has assisted in achieving rapid access to vaccine in emergencies. Recent WHO prequalification of a second affordable OCV supports the stockpile goals of increased availability and distribution to affected populations. It serves as an essential step toward an integrated cholera control and prevention strategy in emergency and endemic settings.
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Lopez AL, Gonzales MLA, Aldaba JG, Nair GB. Killed oral cholera vaccines: history, development and implementation challenges. Ther Adv Vaccines 2014; 2:123-36. [PMID: 25177492 DOI: 10.1177/2051013614537819] [Citation(s) in RCA: 35] [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] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cholera is still a major global health problem, affecting mainly people living in unsanitary conditions and who are at risk for outbreaks of cholera. During the past decade, outbreaks are increasingly reported from more countries. From the early killed oral cholera vaccine, rapid improvements in vaccine development occurred as a result of a better understanding of the epidemiology of the disease, pathogenesis of cholera infection and immunity. The newer-generation oral killed cholera vaccines have been shown to be safe and effective in field trials conducted in cholera endemic areas. Likewise, they have been shown to be protective when used during outbreak settings. Aside from providing direct protection to vaccinated individuals, recent studies have demonstrated that these killed oral vaccines also confer indirect protection through herd immunity. Although new-generation oral cholera vaccines should not be considered in isolation from other preventive approaches in countries where they are most needed, especially improved water quality and sanitation, these vaccines serve as immediately available public health tools for preventing further morbidity and mortality from cholera. However, despite its availability for more than two decades, use of these vaccines has not been optimized. Although there are limitations of the currently available oral cholera vaccines, recent data show that the vaccines are safe, feasible to use even in difficult circumstances and able to provide protection in various settings. Clear identification of the areas and target population groups who will benefit from the use of the cholera vaccines will be required and strategies to facilitate accessibility and usage of these vaccines in these areas and population groups will need to be developed.
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Affiliation(s)
- Anna Lena Lopez
- Institute of Child Health and Human Development, University of the Philippines Manila-National Institutes of Health, 623 P. Gil St., Manila 1000, Philippines
| | | | - Josephine G Aldaba
- Institute of Child Health and Human Development, National Institutes of Health, University of the Philippines Manila, Manila, Philippines
| | - G Balakrish Nair
- Translational Health Science and Technology Institute, Haryana, India
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Sánchez J, Holmgren J. Cholera toxin - a foe & a friend. Indian J Med Res 2011; 133:153-63. [PMID: 21415489 PMCID: PMC3089046] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
After De΄s pivotal demonstration in 1959 of a diarrhoeogenic exo-enterotoxin in cell-free culture filtrates from Vibrio cholerae (of classical biotype), much insight has been gained about cholera toxin (CT), which is arguably now the best known of all microbial toxins. The subunit structure and function of CT, its receptor (the GM1 ganglioside), and its effects on the cyclic AMP system and on intestinal secretion were defined in the 1970s, and the essential aspects of the genetic organization in the 1980s. Recent findings have generated additional perspectives. The 3D-crystal structure of CT has been established, the CT-encoding operon has been shown to be carried by a non-lytic bacteriophage, and in depth knowledge has been gained on how the bacterium controls CT gene expression in response to cell density and various environmental signals. The mode of entry into target cells and the intracellular transport of CT are becoming clearer. CT has become the prototype enterotoxin and a widely used tool for elucidating important aspects of cell biology and physiology, e.g., cell membrane receptors, the cyclic AMP system, G proteins, as well as normal and pathological ion transport mechanisms. In immunology, CT has emerged as a potent, widely used experimental adjuvant, and the strong oral-mucosal immunogenicity of the non-toxic B-subunit (CTB) has led to the use of CTB as a protective antigen together with killed vibrios in a widely licensed oral cholera vaccine. CTB has also been shown to promote immunological tolerance against certain types of mucosally co-administered antigens, preferably tissue antigens linked to the CTB molecule; this has stimulated research and development to use CTB in this context for treatment of autoimmune and allergic diseases. In summary, in the 50 years after De΄s discovery of CT, this molecule has emerged from being the cholera patient΄s "foe" to also becoming a highly useful scientist΄s "friend".
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Affiliation(s)
- Joaquín Sánchez
- Facultad de Medicina, UAEM, Av. Universidad, Col. Chamilpa, Mexico
| | - Jan Holmgren
- University of Gothenburg Vaccine Research Institute (GUVAX) & Department of Microbiology & Immunology, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden,Reprint requests: Dr Jan Holmgren, University of Gothenburg Vaccine Research Institute (GUVAX) & Department of Microbiology & Immunology, The Sahlgrenska Academy at University of Gothenburg, Box 435, S-405 30 Gothenburg, Sweden e-mail:
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Abstract
Vaccines consisting of transgenic plant-derived antigens offer a new strategy for development of safe, inexpensive vaccines. The vaccine antigens can be eaten with the edible part of the plant or purified from plant material. In phase 1 clinical studies of prototype potato- and corn-based vaccines, these vaccines have been safe and immunogenic without the need for a buffer or vehicle other than the plant cell. Transgenic plant technology is attractive for vaccine development because these vaccines are needle-less, stable, and easy to administer. This chapter examines some early human studies of oral transgenic plant-derived vaccines against enterotoxigenic Escherichia coli infection, norovirus, and hepatitis B.
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Affiliation(s)
- Alexander V. Karasev
- grid.266456.50000000122849900Department of Plant, Soil & Entomological Sciences, University of Idaho, Moscow, ID 83844-2339 USA
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