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Abstract
Malaria is a mosquito-borne disease caused by protozoan parasites of the genus Plasmodium. Despite significant declines in malaria-attributable morbidity and mortality over the last two decades, it remains a major public health burden in many countries. This underscores the critical need for improved strategies to prevent, treat and control malaria if we are to ultimately progress towards the eradication of this disease. Ideally, this will include the development and deployment of a highly effective malaria vaccine that is able to induce long-lasting protective immunity. There are many malaria vaccine candidates in development, with more than a dozen of these in clinical development. RTS,S/AS01 (also known as Mosquirix) is the most advanced malaria vaccine and was shown to have modest efficacy against clinical malaria in phase III trials in 5- to 17-month-old infants. Following pilot implementation trials, the World Health Organisation has recommended it for use in Africa in young children who are most at risk of infection with P. falciparum, the deadliest of the human malaria parasites. It is well recognised that more effective malaria vaccines are needed. In this review, we discuss malaria vaccine candidates that have progressed into clinical evaluation and highlight the most advanced candidates: Sanaria's irradiated sporozoite vaccine (PfSPZ Vaccine), the chemoattenuated sporozoite vaccine (PfSPZ-CVac), RTS,S/AS01 and the novel malaria vaccine candidate, R21, which displayed promising, high-level efficacy in a recent small phase IIb trial in Africa.
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Affiliation(s)
- Danielle I Stanisic
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia.
| | - Michael F Good
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia.
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2
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Yihunie W, Kebede B, Tegegne BA, Getachew M, Abebe D, Aschale Y, Belew H, Bahiru B. Systematic Review of Safety of RTS,S with AS01 and AS02 Adjuvant Systems Using Data from Randomized Controlled Trials in Infants, Children, and Adults. Clin Pharmacol 2023; 15:21-32. [PMID: 36941908 PMCID: PMC10024506 DOI: 10.2147/cpaa.s400155] [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: 12/15/2022] [Accepted: 03/07/2023] [Indexed: 03/16/2023] Open
Abstract
Background Emergence of antimalarial drugs and insecticides resistance alarms scientists to develop a safe and effective malaria vaccine. A pre-erythrocytic malaria vaccine called RTS,S has made great strides. Aim The review was aimed to assess the safety of the candidate malaria vaccine RTS,S with AS01 and AS02 adjuvants using data from Phase I-III randomized controlled clinical trials (RCTs). Methods This systematic review was conducted based on PRISMA 2020. Regardless of time of publication year, all articles related with safety of RTS,S, RCTs published in the English language were included in the study. The last search of databases, and registry was conducted on 30 May, 2022. Pubmed, Google Scholar, Cochrane Library, Wiley Online Library, and Clinical trials.gov were thoroughly searched for accessible RCTs on the safety of RTS,S malaria vaccine. The studies were screened in three steps: duplicate removal, title and abstract screening, and full-text review. The included studies' bias risk was assessed using the Cochrane risk of bias tool for RCTs. This systematic review is registered at Prospero (registration number: CRD42021285888). The qualitative descriptive findings from the included published studies were reported stratified by clinical trial phases. Findings A total of thirty-five eligible safety studies were identified. Injection site pain and swelling, febrile convulsion, fever, headache, meningitis, fatigue, gastroenteritis, myalgia, pneumonia, reactogenicity, and anemia were the most commonly reported adverse events. Despite few clinical trials reported serious adverse events, none of them were related to vaccination. Conclusion Most of the adverse events observed from RTS,S/AS01 and RTS,S/AS02 malaria vaccines were reported in the control group and shared by other vaccines. Hence, the authors concluded that both RTS,S/AS01 and RTS,S/AS02 malaria vaccines are safe.
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Affiliation(s)
- Wubetu Yihunie
- Department of Pharmacy, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Bekalu Kebede
- Department of Pharmacy, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Bantayehu Addis Tegegne
- Department of Pharmacy, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Melese Getachew
- Department of Pharmacy, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Dehnnet Abebe
- Department of Pharmacy, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Yibeltal Aschale
- Department of Medical Laboratory Science, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Habtamu Belew
- Department of Medical Laboratory Science, College of Health Sciences, Debre Markos University, Debre Markos, Ethiopia
| | - Bereket Bahiru
- Department of Pharmacy, College of Medicine and health sciences, Bahir Dar University, Bahir Dar, Ethiopia
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3
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Nirmolia T, Ahmed MA, Sathishkumar V, Sarma NP, Bhattacharyya DR, Mohapatra PK, Bansal D, Bharti PK, Sehgal R, Mahanta J, Sultan AA, Narain K, Patgiri SJ. Genetic diversity of Plasmodium falciparum AMA-1 antigen from the Northeast Indian state of Tripura and comparison with global sequences: implications for vaccine development. Malar J 2022; 21:62. [PMID: 35193607 PMCID: PMC8861999 DOI: 10.1186/s12936-022-04081-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 02/07/2022] [Indexed: 11/18/2022] Open
Abstract
Background Malaria continues to be a major public health problem in the Northeastern part of India despite the implementation of vector control measures and changes in drug policies. To develop successful vaccines against malaria, it is important to assess the diversity of vaccine candidate antigens in field isolates. This study was done to assess the diversity of Plasmodium falciparum AMA-1 vaccine candidate antigen in a malaria-endemic region of Tripura in Northeast India and compare it with previously reported global isolates with a view to assess the feasibility of developing a universal vaccine based on this antigen. Methods Patients with fever and malaria-like illness were screened for malaria and P. falciparum positive cases were recruited for the current study. The diversity of PfAMA-1 vaccine candidate antigen was evaluated by nested PCR and RFLP. A selected number of samples were sequenced using the Sanger technique. Results Among 56 P. falciparum positive isolates, Pfama-1 was successfully amplified in 75% (n = 42) isolates. Allele frequencies of PfAMA-1 antigen were 16.6% (n = 7) for 3D7 allele and 33.3% (n = 14) in both K1 and HB3 alleles. DNA sequencing revealed 13 haplotypes in the Pfama-1 gene including three unique haplotypes not reported earlier. No unique amino-acid substitutions were found. Global analysis with 2761 sequences revealed 435 haplotypes with a very complex network composition and few clusters. Nucleotide diversity for Tripura (0.02582 ± 0.00160) showed concordance with South-East Asian isolates while recombination parameter (Rm = 8) was lower than previous reports from India. Population genetic structure showed moderate differentiation. Conclusions Besides documenting all previously reported allelic forms of the vaccine candidate PfAMA-1 antigen of P. falciparum, new haplotypes not reported earlier, were found in Tripura. Neutrality tests indicate that the Pfama-1 population in Tripura is under balancing selection. This is consistent with global patterns. However, the high haplotype diversity observed in the global Pfama-1 network analysis indicates that designing a universal vaccine based on this antigen may be difficult. This information adds to the existing database of genetic diversity of field isolates of P. falciparum and may be helpful in the development of more effective vaccines against the parasite. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04081-1.
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Affiliation(s)
- Tulika Nirmolia
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Md Atique Ahmed
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Vinayagam Sathishkumar
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Nilanju P Sarma
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India.,SRL Reference Laboratory, Mumbai, 400060, India
| | - Dibya R Bhattacharyya
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Pradyumna K Mohapatra
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Devendra Bansal
- Department of Microbiology and Immunology, Weill Cornell Medicine - Qatar, Cornell University, Doha, Qatar.,Ministry of Public Health, Doha, Qatar
| | - Praveen K Bharti
- ICMR - National Institute for Research in Tribal Health, Jabalpur, Madhya Pradesh, 482003, India
| | - Rakesh Sehgal
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, 160012, India
| | - Jagadish Mahanta
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Ali A Sultan
- Department of Microbiology and Immunology, Weill Cornell Medicine - Qatar, Cornell University, Doha, Qatar
| | - Kanwar Narain
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India
| | - Saurav J Patgiri
- ICMR - Regional Medical Research Centre, North East Region, Dibrugarh, Assam, 786001, India.
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4
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Kusi KA, Ofori EA, Akyea-Mensah K, Kyei-Baafour E, Frimpong A, Ennuson NA, Belmonte M, Ganeshan H, Huang J, Amoah LE, Villasante E, Sedegah M. Towards large-scale identification of HLA-restricted T cell epitopes from four vaccine candidate antigens in a malaria endemic community in Ghana. Vaccine 2021; 40:757-764. [PMID: 34969544 DOI: 10.1016/j.vaccine.2021.12.042] [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: 05/14/2021] [Revised: 12/06/2021] [Accepted: 12/16/2021] [Indexed: 11/24/2022]
Abstract
Sterile protection against clinical malaria has been achieved in animal models and experimental human challenge studies involving immunization with radiation attenuated Plasmodium falciparum sporozoite vaccines as well as by live sporozoites under chloroquine prophylaxis. Parasite-specific IFN-γ and granzyme B-secreting CD8 + T cells have been identified as key mediators of protection. Although the exact parasite targets of protective CD8 + T cell responses are not fully defined, responses against a handful of vaccine candidate antigens have been associated with protection. Identifying the T cell targets in these antigens will facilitate the development of simpler, cost-effective, and efficacious next generation multi-epitope vaccines. The aim of this study was to identify immunodominant portions of four malaria vaccine candidate antigens using peripheral blood mononuclear cells (PBMCs) from adults with life-long exposure to malaria parasites. Cryopreserved PBMCs from 291 HLA-typed subjects were stimulated with pools of overlapping 15mer peptides spanning the entire sequences of P. falciparum circumsporozoite protein (CSP, 9 pools), apical membrane antigen 1 (AMA1, 12 pools), thrombospondin related anonymous protein (TRAP, 6 pools) and cell traversal for ookinetes and sporozoites (CelTOS, 4 pools) in FluoroSpot assays. 125 of 291 subjects made IFN-γ responses to 30 of the 31 peptide pools tested and 22 of 291 made granzyme B responses, with 20 making dual responses. The most frequent responses were to the CSP C-terminal region and the least frequent responses were to TRAP and CelTOS. There was no association between FluoroSpot responses and active malaria infection, detected by either microscopy, RDT, or PCR. In conclusion, CSP and AMA1 have relatively higher numbers of epitopes that trigger IFN-γ and granzyme B-secreting T cells in adults with life-long malaria parasite exposure compared to the other two antigens tested, and highlights the continued relevance of these two antigens as vaccine candidates.
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Affiliation(s)
- Kwadwo Asamoah Kusi
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana.
| | - Ebenezer Addo Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Kwadwo Akyea-Mensah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Eric Kyei-Baafour
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Augustina Frimpong
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Nana Aba Ennuson
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Maria Belmonte
- Malaria Department, Naval Medical Research Center, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Harini Ganeshan
- Malaria Department, Naval Medical Research Center, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Jun Huang
- Malaria Department, Naval Medical Research Center, MD, USA; Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Linda Eva Amoah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | | | - Martha Sedegah
- Malaria Department, Naval Medical Research Center, MD, USA
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5
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Abstract
Introduction: An effective vaccine against malaria forms a global health priority. Both naturally acquired immunity and sterile protection induced by irradiated sporozoite immunization were described decades ago. Still no vaccine exists that sufficiently protects children in endemic areas. Identifying immunological correlates of vaccine efficacy can inform rational vaccine design and potentially accelerate clinical development.Areas covered: We discuss recent research on immunological correlates of malaria vaccine efficacy, including: insights from state-of-the-art omics platforms and systems vaccinology analyses; functional anti-parasitic assays; pre-immunization predictors of vaccine efficacy; and comparison of correlates of vaccine efficacy against controlled human malaria infections (CHMI) and against naturally acquired infections.Expert Opinion: Effective vaccination may be achievable without necessarily understanding immunological correlates, but the relatively disappointing efficacy of malaria vaccine candidates in target populations is concerning. Hypothesis-generating omics and systems vaccinology analyses, alongside assessment of pre-immunization correlates, have the potential to bring about paradigm-shifts in malaria vaccinology. Functional assays may represent in vivo effector mechanisms, but have scarcely been formally assessed as correlates. Crucially, evidence is still meager that correlates of vaccine efficacy against CHMI correspond with those against naturally acquired infections in target populations. Finally, the diversity of immunological assays and efficacy endpoints across malaria vaccine trials remains a major confounder.
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Affiliation(s)
| | - Matthew B B McCall
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, The Netherlands.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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6
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Almeida MEMD, Vasconcelos MGSD, Tarragô AM, Mariúba LAM. Circumsporozoite Surface Protein-based malaria vaccines: a review. Rev Inst Med Trop Sao Paulo 2021; 63:e11. [PMID: 33533814 PMCID: PMC7845937 DOI: 10.1590/s1678-9946202163011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 10/20/2020] [Indexed: 12/03/2022] Open
Abstract
Malaria represents a serious public health problem, presenting with high rates of incidence, morbidity and mortality in tropical and subtropical regions of the world. According to the World Health Organization, in 2018 there were 228 million cases and 405 thousand deaths caused by this disease in the world, affecting mainly children and pregnant women in Africa. Despite the programs carried out to control this disease, drug resistance and invertebrate vector resistance to insecticides have generated difficulties. An efficient vaccine against malaria would be a strategy with a high impact on the eradication and control of this disease. Researches aimed at developing vaccines have focused on antigens of high importance for the survival of the parasite such as the Circumsporozoite Surface Protein, involved in the pre-erythrocytic cycle during parasites invasion in hepatocytes. Currently, RTS’S is the most promising vaccine for malaria and was constructed using CSP; its performance was evaluated using two types of adjuvants: AS01 and AS02. The purpose of this review was to provide a bibliographic survey of historical researches that led to the development of RTS’S and its performance analysis over the decade. The search for new adjuvants to be associated with this antigen seems to be a way to obtain higher percentages of protection for a future malaria vaccine.
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Affiliation(s)
- Maria Edilene Martins de Almeida
- Fiocruz Amazônia, Instituto Leônidas e Maria Deane, Laboratório de Diagnóstico e Controle de Doenças Infecciosas na Amazônia, Amazonas, Manaus, Brazil.,Fiocruz, Instituto Oswaldo Cruz, Programa de Pós-Graduação Stricto Sensu em Biologia Celular e Molecular, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maria Gabriella Santos de Vasconcelos
- Fiocruz Amazônia, Instituto Leônidas e Maria Deane, Laboratório de Diagnóstico e Controle de Doenças Infecciosas na Amazônia, Amazonas, Manaus, Brazil.,Centro Universitário Fametro, Manaus, Amazonas, Brazil
| | - Andréa Monteiro Tarragô
- Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Imunologia Básica e Aplicada, Manaus, Amazonas, Brazil.,Fundação Hospitalar de Hematologia e Hemoterapia do Amazonas, Manaus, Amazonas, Brazil
| | - Luís André Morais Mariúba
- Fiocruz Amazônia, Instituto Leônidas e Maria Deane, Laboratório de Diagnóstico e Controle de Doenças Infecciosas na Amazônia, Amazonas, Manaus, Brazil.,Fiocruz, Instituto Oswaldo Cruz, Programa de Pós-Graduação Stricto Sensu em Biologia Celular e Molecular, Rio de Janeiro, Rio de Janeiro, Brazil.,Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Imunologia Básica e Aplicada, Manaus, Amazonas, Brazil.,Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Programa de Pós-Graduação em Biotecnologia, Manaus, Amazonas, Brazil
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7
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Affiliation(s)
- Conrad Keating
- School of Medicine, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
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8
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Beeson JG, Kurtovic L, Dobaño C, Opi DH, Chan JA, Feng G, Good MF, Reiling L, Boyle MJ. Challenges and strategies for developing efficacious and long-lasting malaria vaccines. Sci Transl Med 2019; 11:11/474/eaau1458. [DOI: 10.1126/scitranslmed.aau1458] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 08/05/2018] [Accepted: 11/02/2018] [Indexed: 12/24/2022]
Abstract
Although there has been major recent progress in malaria vaccine development, substantial challenges remain for achieving highly efficacious and durable vaccines against Plasmodium falciparum and Plasmodium vivax malaria. Greater knowledge of mechanisms and key targets of immunity are needed to accomplish this goal, together with new strategies for generating potent, long-lasting, functional immunity against multiple antigens. Implementation considerations in endemic areas will ultimately affect vaccine effectiveness, so innovations to simplify and enhance delivery are also needed. Whereas challenges remain, recent exciting progress and emerging knowledge promise hope for the future of malaria vaccines.
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9
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Jairaj A, Shirisha P, Abdul MSM, Fatima U, Tiwari RVC, Moothedath M. Adult Immunization - Need of the Hour. J Int Soc Prev Community Dent 2018; 8:475-481. [PMID: 30596036 PMCID: PMC6280562 DOI: 10.4103/jispcd.jispcd_347_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 10/16/2018] [Indexed: 11/15/2022] Open
Abstract
Immunization is the process of making individuals immune. Childhood immunization is a common process for various aliments, but adult immunization in the Indian scenario is obscure. Officially, India has been declared polio-free, which is an achievement despite cultural, political, economic, geographic, and so many other factors. The changing demographics of adult, geriatric population and growing cost of health-care maintenance are a concern in developing countries like India. Thus, promoting healthy lifestyle needs prevention, early detection, and management of various diseases and disorders. Certainly, prevention in adults is yet to be tapped completely, so that goal of 100% prevention can be achieved. Various fraternities of medical association have come up with guidelines for adult immunization schedules in India. The present paper reviews infectious diseases such as anthrax, chikungunya, cholera, dengue, influenza, and malaria in this section of the review. We humbly request all health-care professionals and educators to educate the mass for adult immunization. So that, cost involved for treatment and workforce for the management of diseases can be better utilized in some other needed areas.
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Affiliation(s)
| | - P Shirisha
- Department of Humanities and Social Sciences, IIT Madras, Chennai, Tamil Nadu, India
| | | | - Urooj Fatima
- Skin and Laser Care Centre, Dr. Sulaiman Al Habib Hospital, Riyadh, Saudi Arabia
| | - Rahul Vinay Chandra Tiwari
- Department of Oral and Maxillofacial Surgery and Dentistry, Jubilee Mission Medical College Hospital and Research Center, Thrissur, Kerala, India
| | - Muhamood Moothedath
- Department of Public Health Dentistry, College of Applied Health Sciences in Ar Rass, Qassim University, Buraydah, Saudi Arabia
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10
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McCall MBB, Kremsner PG, Mordmüller B. Correlating efficacy and immunogenicity in malaria vaccine trials. Semin Immunol 2018; 39:52-64. [PMID: 30219621 DOI: 10.1016/j.smim.2018.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 08/06/2018] [Indexed: 12/19/2022]
Abstract
The availability of an effective and appropriately implemented malaria vaccine would form a crucial cornerstone of public health efforts to fight this disease. Despite many decades of research, however, no malaria vaccine has yet shown satisfactory protective efficacy or been rolled-out. Validated immunological substitute endpoints have the potential to accelerate clinical vaccine development by reducing the required complexity, size, duration and cost of clinical trials. Besides facilitating clinical development of existing vaccine candidates, understanding immunological mechanisms of protection may drive the development of fundamentally new vaccination approaches. In this review we focus on correlates of protection in malaria vaccine development: Does immunogenicity predict malaria vaccine efficacy and why is this question particularly difficult? Have immunological correlates accelerated malaria vaccine development in the past and will they facilitate it in the future? Does Controlled Human Malaria Infection represent a valid model for identifying such immunological correlates, or a correlate of protection against naturally-acquired malaria in itself?
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Affiliation(s)
- Matthew B B McCall
- Institut für Tropenmedizin, Universität Tübingen and Deutsches Zentrum für Infektionsforschung, Germany; Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon.
| | - Peter G Kremsner
- Institut für Tropenmedizin, Universität Tübingen and Deutsches Zentrum für Infektionsforschung, Germany; Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | - Benjamin Mordmüller
- Institut für Tropenmedizin, Universität Tübingen and Deutsches Zentrum für Infektionsforschung, Germany; Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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11
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Nilsson Bark SK, Ahmad R, Dantzler K, Lukens AK, De Niz M, Szucs MJ, Jin X, Cotton J, Hoffmann D, Bric-Furlong E, Oomen R, Parrington M, Milner D, Neafsey DE, Carr SA, Wirth DF, Marti M. Quantitative Proteomic Profiling Reveals Novel Plasmodium falciparum Surface Antigens and Possible Vaccine Candidates. Mol Cell Proteomics 2017; 17:43-60. [PMID: 29162636 DOI: 10.1074/mcp.ra117.000076] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 09/20/2017] [Indexed: 12/30/2022] Open
Abstract
Despite recent efforts toward control and elimination, malaria remains a major public health problem worldwide. Plasmodium falciparum resistance against artemisinin, used in front line combination drugs, is on the rise, and the only approved vaccine shows limited efficacy. Combinations of novel and tailored drug and vaccine interventions are required to maintain the momentum of the current malaria elimination program. Current evidence suggests that strain-transcendent protection against malaria infection can be achieved using whole organism vaccination or with a polyvalent vaccine covering multiple antigens or epitopes. These approaches have been successfully applied to the human-infective sporozoite stage. Both systemic and tissue-specific pathology during infection with the human malaria parasite P. falciparum is caused by asexual blood stages. Tissue tropism and vascular sequestration are the result of specific binding interactions between antigens on the parasite-infected red blood cell (pRBC) surface and endothelial receptors. The major surface antigen and parasite ligand binding to endothelial receptors, PfEMP1 is encoded by about 60 variants per genome and shows high sequence diversity across strains. Apart from PfEMP1 and three additional variant surface antigen families RIFIN, STEVOR, and SURFIN, systematic analysis of the infected red blood cell surface is lacking. Here we present the most comprehensive proteomic investigation of the parasitized red blood cell surface so far. Apart from the known variant surface antigens, we identified a set of putative single copy surface antigens with low sequence diversity, several of which are validated in a series of complementary experiments. Further functional and immunological investigation is underway to test these novel P. falciparum blood stage proteins as possible vaccine candidates.
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Affiliation(s)
- Sandra K Nilsson Bark
- From the ‡Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115
| | - Rushdy Ahmad
- §The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Kathleen Dantzler
- From the ‡Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115.,¶Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8TA, UK
| | - Amanda K Lukens
- From the ‡Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115.,§The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Mariana De Niz
- ¶Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8TA, UK
| | - Matthew J Szucs
- §The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Xiaoying Jin
- ‖Sanofi Biopharmaceutics Development, Framingham, Massachusetts 02142
| | - Joanne Cotton
- ‖Sanofi Biopharmaceutics Development, Framingham, Massachusetts 02142
| | | | | | - Ray Oomen
- **Sanofi Pasteur Biologics, Cambridge, Massachusetts 02139
| | | | - Dan Milner
- From the ‡Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115.,‡‡Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Daniel E Neafsey
- §The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Steven A Carr
- §The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Dyann F Wirth
- From the ‡Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115.,§The Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142
| | - Matthias Marti
- From the ‡Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115; .,¶Wellcome Centre for Molecular Parasitology, University of Glasgow, Glasgow G12 8TA, UK
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12
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Stassijns J, Bollaerts K, Baay M, Verstraeten T. A systematic review and meta-analysis on the safety of newly adjuvanted vaccines among children. Vaccine 2015; 34:714-22. [PMID: 26740250 DOI: 10.1016/j.vaccine.2015.12.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/08/2015] [Accepted: 12/10/2015] [Indexed: 12/15/2022]
Abstract
INTRODUCTION New adjuvants such as the AS- or the MF59-adjuvants improve vaccine efficacy and facilitate dose-sparing. Their use in influenza and malaria vaccines has resulted in a large body of evidence on their clinical safety in children. METHODS We carried out a systematic search for safety data from published clinical trials on newly adjuvanted vaccines in children ≤10 years of age. Serious adverse events (SAEs), solicited AEs, unsolicited AEs and AEs of special interest were evaluated for four new adjuvants: the immuno-stimulants containing adjuvant systems AS01 and AS02, and the squalene containing oil-in-water emulsions AS03 and MF59. Relative risks (RR) were calculated, comparing children receiving newly adjuvanted vaccines to children receiving other vaccines with a variety of antigens, both adjuvanted and unadjuvanted. RESULTS Twenty-nine trials were included in the meta-analysis, encompassing 25,056 children who received at least one dose of the newly adjuvanted vaccines. SAEs did not occur more frequently in adjuvanted groups (RR 0.85, 95%CI 0.75-0.96). Our meta-analyses showed higher reactogenicity following administration of newly adjuvanted vaccines, however, no consistent pattern of solicited AEs was observed across adjuvant systems. Pain was the most prevalent AE, but often mild and of short duration. No increased risks were found for unsolicited AEs, febrile convulsions, potential immune mediated diseases and new onset of chronic diseases. CONCLUSIONS Our meta-analysis did not show any safety concerns in clinical trials of the newly adjuvanted vaccines in children ≤10 years of age. An unexplained increase of meningitis in one Phase III AS01-adjuvanted malaria trial and the link between narcolepsy and the AS03-adjuvanted pandemic vaccine illustrate that continued safety monitoring is warranted.
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Affiliation(s)
- Jorgen Stassijns
- P-95, Epidemiology and Pharmacovigilance Consulting and Services, Koning Leopold III Laan 1, 3001 Heverlee, Belgium
| | - Kaatje Bollaerts
- P-95, Epidemiology and Pharmacovigilance Consulting and Services, Koning Leopold III Laan 1, 3001 Heverlee, Belgium
| | - Marc Baay
- P-95, Epidemiology and Pharmacovigilance Consulting and Services, Koning Leopold III Laan 1, 3001 Heverlee, Belgium
| | - Thomas Verstraeten
- P-95, Epidemiology and Pharmacovigilance Consulting and Services, Koning Leopold III Laan 1, 3001 Heverlee, Belgium.
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Agnandji ST, Fernandes JF, Bache EB, Ramharter M. Clinical development of RTS,S/AS malaria vaccine: a systematic review of clinical Phase I-III trials. Future Microbiol 2015; 10:1553-78. [PMID: 26437872 DOI: 10.2217/fmb.15.90] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The first clinical Phase III trial evaluating a malaria vaccine was completed in December 2013 at 11 sites from seven sub-Saharan African countries. This systematic review assesses data of Phase I-III trials including malaria-naive adults and adults, children and infants from malaria endemic settings in sub-Saharan Africa. The main endpoint of this systematic review was an analysis of the consistency of efficacy and immunogenicity data from respective Phase I-III trials. In addition, safety data from a pooled analysis of RTS/AS Phase II trials and RTS,S/AS01 Phase III trial were reviewed. The RTS,S/AS01 malaria vaccine may become available on the market in the coming year. If so, further strategies should address challenges on how to optimize vaccine efficacy and implementation of RTS,S/AS01 vaccine within the framework of established malaria control measures.
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Affiliation(s)
- Selidji T Agnandji
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon, Hôpital Albert Schweitzer BP 118, Lambaréné, Gabon.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Germany, Wilhelmstraße 27, 72074 Tübingen, Germany
| | - José F Fernandes
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon, Hôpital Albert Schweitzer BP 118, Lambaréné, Gabon.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Germany, Wilhelmstraße 27, 72074 Tübingen, Germany
| | - Emmanuel B Bache
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon, Hôpital Albert Schweitzer BP 118, Lambaréné, Gabon.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Germany, Wilhelmstraße 27, 72074 Tübingen, Germany
| | - Michael Ramharter
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon, Hôpital Albert Schweitzer BP 118, Lambaréné, Gabon.,Institut für Tropenmedizin, Universitätsklinikum Tübingen, Germany, Wilhelmstraße 27, 72074 Tübingen, Germany.,Department of Medicine I, Division of Infectious Diseases & Tropical Medicine, Medical University of Vienna, Austria, Währinger Gürtel 18-20, 1190 Vienna, Austria
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Sinha S, Medhi B, Sehgal R. Challenges of drug-resistant malaria. ACTA ACUST UNITED AC 2014; 21:61. [PMID: 25402734 PMCID: PMC4234044 DOI: 10.1051/parasite/2014059] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 10/23/2014] [Indexed: 01/09/2023]
Abstract
Over the past six decades, the drug resistance of Plasmodium falciparum has become an issue of utmost concern. Despite the remarkable progress that has been made in recent years in reducing the mortality rate to about 30% with the scaling-up of vector control, introduction of artemisinin-based combination therapies and other malaria control strategies, the confirmation of artemisinin resistance on the Cambodia–Thailand border threatened all the previous success. This review addresses the global scenario of antimalarial resistance and factors associated with it, with the main emphasis on futuristic approaches like nanotechnology and stem cell therapy that may impede resistant malaria, along with novel medications which are preparing to enter the global antimalarial market. These novel studies are likely to escalate over the coming years and will hopefully help to reduce the burden of malaria.
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Affiliation(s)
- Shweta Sinha
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Bikash Medhi
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
| | - Rakesh Sehgal
- Department of Medical Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India
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15
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Kester KE, Gray Heppner D, Moris P, Ofori-Anyinam O, Krzych U, Tornieporth N, McKinney D, Delchambre M, Ockenhouse CF, Voss G, Holland C, Beckey JP, Ballou WR, Cohen J. Sequential Phase 1 and Phase 2 randomized, controlled trials of the safety, immunogenicity and efficacy of combined pre-erythrocytic vaccine antigens RTS,S and TRAP formulated with AS02 Adjuvant System in healthy, malaria naïve adults. Vaccine 2014; 32:6683-91. [PMID: 24950358 DOI: 10.1016/j.vaccine.2014.06.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 05/26/2014] [Accepted: 06/06/2014] [Indexed: 10/25/2022]
Abstract
In an attempt to improve the efficacy of the candidate malaria vaccine RTS,S/AS02, two studies were conducted in 1999 in healthy volunteers of RTS,S/AS02 in combination with recombinant Plasmodium falciparum thrombospondin-related anonymous protein (TRAP). In a Phase 1 safety and immunogenicity study, volunteers were randomized to receive TRAP/AS02 (N=10), RTS,S/AS02 (N=10), or RTS,S+TRAP/AS02 (N=20) at 0, 1 and 6-months. In a Phase 2 challenge study, subjects were randomized to receive either RTS,S+TRAP/AS02 (N=25) or TRAP/AS02 (N=10) at 0 and 1-month, or to a challenge control group (N=8). In both studies, the combination vaccine had an acceptable safety profile and was acceptably tolerated. Antigen-specific antibodies, lymphoproliferative responses, and IFN-γ production by ELISPOT assay elicited with the combination vaccine were qualitatively similar to those generated by the single component vaccines. However, post-dose 2 anti-CS antibodies in the RTS,S+TRAP/AS02 vaccine recipients were lower than in the RTS,S/AS02 vaccine recipients. After challenge, 10 of 11 RTS,S+TRAP/AS02 vaccinees, 5 of 5 TRAP/AS02 vaccinees, and 8 of 8 infectivity controls developed parasitemia, with median pre-patent periods of 13.0, 11.0, and 12.0 days, respectively. The absence of any prevention or delay of parasitemia by TRAP/AS02 suggests no apparent added value of TRAP/AS02 as a candidate vaccine. The absence of significant protection or delay of parasitemia in the 11 RTS,S+TRAP/AS02 vaccine recipients contrasts with previous 2 dose studies of RTS,S/AS02. The small sample size did not permit identifying statistically significant differences between the study arms. However, we speculate, within the constraints of the challenge study, that the presence of the TRAP antigen may have interfered with the vaccine efficacy previously observed with this regimen of RTS,S/AS02, and that any future TRAP-based vaccines should consider employing alternative vaccine platforms.
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Affiliation(s)
- Kent E Kester
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - D Gray Heppner
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | | | | | - Urszula Krzych
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | | | - Denise McKinney
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | | | | | - Gerald Voss
- GlaxoSmithKline Biologicals, Rixensart, Belgium.
| | - Carolyn Holland
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | | | - W Ripley Ballou
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - Joe Cohen
- GlaxoSmithKline Biologicals, Rixensart, Belgium.
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Duration of vaccine efficacy against malaria: 5th year of follow-up in children vaccinated with RTS,S/AS02 in Mozambique. Vaccine 2014; 32:2209-16. [PMID: 24631081 DOI: 10.1016/j.vaccine.2014.02.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 12/18/2013] [Accepted: 02/12/2014] [Indexed: 02/07/2023]
Abstract
A primary concern for the RTS,S malaria vaccine candidate is duration of protection. The ongoing Phase III trial reported evidence of waning efficacy within the first year following vaccination. Multiple Phase IIb trials demonstrated early waning of efficacy. The longest duration of protection for RTS,S recorded to date was in a trial of a cohort of 1605 Mozambican children age 1-4 yr at the time of immunization (C1), which showed an overall efficacy against clinical malaria of 30.5% over 43 subsequent months of surveillance. A significant reduction in parasite prevalence in RTS,S vaccinees indicated that the vaccine continued to protect at the end of this period. Although follow-up for recording incident cases of clinical malaria was stopped at 45 months, we were interested in evidence of further durability of protection, and revisited the cohort at 63 months, recording the secondary trial endpoint, prevalence of asexual Plasmodium falciparum parasitemia, in the RTS,S and comparator vaccine groups as a proxy for efficacy. As a comparator, we also visited the contemporaneous cohort of 417 children (C2), which showed waning efficacy after 6 months of follow-up. We also assessed anti-circumsporozoite antibody titers. These results were compared with those of other Phase IIb trials. Prevalence of parasitemia was not significantly lower in the RTS,S/AS02 group compared to comparator groups in C1 (57 [119%] Vs 62 [128%]; p=0.696) or C2 (30 [226%] Vs 35 [276%]; p=0.391), despite elevated antibody titers, suggesting that protection did not extend to 5 years after vaccination. This is in contrast to the earlier assessment of parasitemia in C1, where a 34% lower prevalence of parasitemia was observed in the RTS,S/AS02 group at month 45. Comparison with other Phase II trials highlights a complex relationship between efficacy, age and transmission intensity. RTS,S/AS02 provided partial protection from clinical malaria for at least 3.5 years in C1. Duration of protection may depend on environmental circumstances, such as changing malaria transmission, and special attention should be given in the Phase III trial to identifying factors that modify longevity of protection.
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Foquet L, Hermsen CC, van Gemert GJ, Van Braeckel E, Weening KE, Sauerwein R, Meuleman P, Leroux-Roels G. Vaccine-induced monoclonal antibodies targeting circumsporozoite protein prevent Plasmodium falciparum infection. J Clin Invest 2014; 124:140-4. [PMID: 24292709 DOI: 10.1172/jci70349] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 09/26/2013] [Indexed: 11/17/2022] Open
Abstract
Malaria, which is the result of Plasmodium falciparum infection, is a global health threat that resulted in 655,000 deaths and 216 million clinical cases in 2010 alone. Recent phase 3 trials with malaria vaccine candidate RTS,S/AS01 (RTS,S) in children has demonstrated modest efficacy against clinical and severe malaria. RTS,S targets the pre-erythrocytic phase of the disease and induces high antibody titers against the P. falciparum circumsporozoite protein (CSP) and a moderate CD4(+) T cell response. The individual contribution of these adaptive immune responses to protection from infection remains unknown. Here, we found that prophylactic administration of anti-CSP mAbs derived from an RTS,S-vaccinated recipient fully protected mice with humanized livers from i.v.- and mosquito bite–delivered P. falciparum sporozoite challenge. Titers of anti-CSP that conveyed full protection were within the range observed in human RTS,S vaccine recipients. Increasing anti-CSP titers resulted in a dose-dependent reduction of the liver parasite burden. These data indicate that RTS,S-induced antibodies are protective and provide sterilizing immunity against P. falciparum infection when reaching or exceeding a critical plasma concentration.
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Malaria vaccine adjuvants: latest update and challenges in preclinical and clinical research. BIOMED RESEARCH INTERNATIONAL 2013; 2013:282913. [PMID: 23710439 PMCID: PMC3655447 DOI: 10.1155/2013/282913] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 03/21/2013] [Indexed: 12/11/2022]
Abstract
There is no malaria vaccine currently available, and the most advanced candidate has recently reported a modest 30% efficacy against clinical malaria. Although many efforts have been dedicated to achieve this goal, the research was mainly directed to identify antigenic targets. Nevertheless, the latest progresses on understanding how immune system works and the data recovered from vaccination studies have conferred to the vaccine formulation its deserved relevance. Additionally to the antigen nature, the manner in which it is presented (delivery adjuvants) as well as the immunostimulatory effect of the formulation components (immunostimulants) modulates the immune response elicited. Protective immunity against malaria requires the induction of humoral, antibody-dependent cellular inhibition (ADCI) and effector and memory cell responses. This review summarizes the status of adjuvants that have been or are being employed in the malaria vaccine development, focusing on the pharmaceutical and immunological aspects, as well as on their immunization outcomings at clinical and preclinical stages.
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Alonso PL, Tanner M. Public health challenges and prospects for malaria control and elimination. Nat Med 2013; 19:150-5. [PMID: 23389615 DOI: 10.1038/nm.3077] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 10/29/2012] [Indexed: 11/09/2022]
Abstract
The past decade witnessed unprecedented efforts to control malaria, including renewed political and financial commitment and increased availability of both old and new strategies and tools. However, malaria still represents a major health burden, particularly in Africa. Important challenges such as the fragility of many health systems, the rise of insecticide and drug resistance, and particularly the expected decline both in funding and in the coverage of key interventions if they are not replaced as needed, urgently need to be addressed. Further research and development is also becoming increasingly crucial. Among other needs, common methodologies for estimating and tracking the malaria burden, new strategies to measure transmission, better understanding of immunity, and increased knowledge of the mechanisms and effects of resistance to drugs and insecticides stand out. The ongoing efforts in research and development for new antimalarial drugs, more sensitive point-of-care rapid diagnostic tests and new insecticides need further innovation and substantial strengthening. Clearly, efforts should focus not only on Plasmodium falciparum but also and increasingly on Plasmodium vivax, the neglected human malaria parasite. Addressing these challenges in a comprehensive and timely way will allow us to sustain the gains made so far and make further progress in control and progressive elimination.
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Affiliation(s)
- Pedro L Alonso
- Barcelona Centre for International Health Research, Hospital Clinic, Universitat de Barcelona, Spain.
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20
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Abdulla S, Salim N, Machera F, Kamata R, Juma O, Shomari M, Kubhoja S, Mohammed A, Mwangoka G, Aebi T, Mshinda H, Schellenberg D, Carter T, Villafana T, Dubois MC, Leach A, Lievens M, Vekemans J, Cohen J, Ballou WR, Tanner M. Randomized, controlled trial of the long term safety, immunogenicity and efficacy of RTS,S/AS02(D) malaria vaccine in infants living in a malaria-endemic region. Malar J 2013; 12:11. [PMID: 23297680 PMCID: PMC3557164 DOI: 10.1186/1475-2875-12-11] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 01/04/2013] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The RTS,S/AS malaria candidate vaccine is being developed with the intent to be delivered, if approved, through the Expanded Programme on Immunization (EPI) of the World Health Organization. Safety, immunogenicity and efficacy of the RTS,S/AS02(D) vaccine candidate when integrated into a standard EPI schedule for infants have been reported over a nine-month surveillance period. This paper describes results following 20 months of follow up. METHODS This Phase IIb, single-centre, randomized controlled trial enrolled 340 infants in Tanzania to receive three doses of RTS,S/AS02(D) or hepatitis B vaccine at 8, 12, and 16 weeks of age. All infants also received DTPw/Hib (diphtheria and tetanus toxoids, whole-cell pertussis vaccine, conjugated Haemophilus influenzae type b vaccine) at the same timepoints. The study was double-blinded to month 9 and single-blinded from months 9 to 20. RESULTS From month 0 to 20, at least one SAE was reported in 57/170 infants who received RTS,S/AS02(D) (33.5%; 95% confidence interval [CI]: 26.5, 41.2) and 62/170 infants who received hepatitis B vaccine (36.5%; 95% CI: 29.2, 44.2). The SAE profile was similar in both vaccine groups; none were considered to be related to vaccination. At month 20, 18 months after completion of vaccination, 71.8% of recipients of RTS,S/AS02(D) and 3.8% of recipients of hepatitis B vaccine had seropositive titres for anti-CS antibodies; seroprotective levels of anti-HBs antibodies remained in 100% of recipients of RTS,S/AS02(D) and 97.7% recipients of hepatitis B vaccine. Anti-HBs antibody GMTs were higher in the RTS,S/AS02(D) group at all post-vaccination time points compared to control. According to protocol population, vaccine efficacy against multiple episodes of malaria disease was 50.7% (95% CI: -6.5 to 77.1, p = 0.072) and 26.7% (95% CI: -33.1 to 59.6, p = 0.307) over 12 and 18 months post vaccination, respectively. In the Intention to Treat population, over the 20-month follow up, vaccine efficacy against multiple episodes of malaria disease was 14.4% (95% CI: -41.9 to 48.4, p = 0.545). CONCLUSIONS The acceptable safety profile and good tolerability of RTS,S/AS02(D) in combination with EPI vaccines previously reported from month 0 to 9 was confirmed over a 20 month surveillance period in this infant population. Antibodies against both CS and HBsAg in the RTS,S/AS02(D) group remained significantly higher compared to control for the study duration. Over 18 months follow up, RTS,S/AS02(D) prevented approximately a quarter of malaria cases in the study population. CLINICAL TRIALS Gov identifier: NCT00289185.
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Affiliation(s)
- Salim Abdulla
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
- Ifakara Health Institute, 360 Kiko Avenue, Mikocheni, PO Box 78373, Dar es Salaam, Tanzania
| | - Nahya Salim
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Francisca Machera
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Richard Kamata
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Omar Juma
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Mwanajaa Shomari
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Sulende Kubhoja
- Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Ali Mohammed
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Grace Mwangoka
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
| | - Thomas Aebi
- Bagamoyo Research and Training Centre of Ifakara Health Institute, Pwani, Tanzania
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Hassan Mshinda
- Tanzania Commission for Science and Technology, Dar es Salaam, Tanzania
| | | | | | | | | | - Amanda Leach
- GlaxoSmithKline Biologicals, Rue De L'Institut 89, Rixensart, Belgium
| | - Marc Lievens
- GlaxoSmithKline Biologicals, Rue De L'Institut 89, Rixensart, Belgium
| | - Johan Vekemans
- GlaxoSmithKline Biologicals, Rue De L'Institut 89, Rixensart, Belgium
| | - Joe Cohen
- GlaxoSmithKline Biologicals, Rue De L'Institut 89, Rixensart, Belgium
| | - W Ripley Ballou
- GlaxoSmithKline Biologicals, Rue De L'Institut 89, Rixensart, Belgium
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
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Clement F, Dewar V, Van Braeckel E, Desombere I, Dewerchin M, Swysen C, Demoitié MA, Jongert E, Cohen J, Leroux-Roels G, Cambron P. Validation of an enzyme-linked immunosorbent assay for the quantification of human IgG directed against the repeat region of the circumsporozoite protein of the parasite Plasmodium falciparum. Malar J 2012; 11:384. [PMID: 23173602 PMCID: PMC3577486 DOI: 10.1186/1475-2875-11-384] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 10/23/2012] [Indexed: 11/13/2022] Open
Abstract
Background Several pre-erythrocytic malaria vaccines based on the circumsporozoite protein (CSP) antigen of Plasmodium falciparum are in clinical development. Vaccine immunogenicity is commonly evaluated by the determination of anti-CSP antibody levels using IgG-based assays, but no standard assay is available to allow comparison of the different vaccines. Methods The validation of an anti-CSP repeat region enzyme-linked immunosorbent assay (ELISA) is described. This assay is based on the binding of serum antibodies to R32LR, a recombinant protein composed of the repeat region of P. falciparum CSP. In addition to the original recombinant R32LR, an easy to purify recombinant His-tagged R32LR protein has been constructed to be used as solid phase antigen in the assay. Also, hybridoma cell lines have been generated producing human anti-R32LR monoclonal antibodies to be used as a potential inexhaustible source of anti-CSP repeats standard, instead of a reference serum. Results The anti-CSP repeats ELISA was shown to be robust, specific and linear within the analytical range, and adequately fulfilled all validation criteria as defined in the ICH guidelines. Furthermore, the coefficient of variation for repeatability and intermediate precision did not exceed 23%. Non-interference was demonstrated for R32LR-binding sera, and the assay was shown to be stable over time. Conclusions This ELISA, specific for antibodies directed against the CSP repeat region, can be used as a standard assay for the determination of humoral immunogenicity in the development of any CSP-based P. falciparum malaria vaccine.
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Zeeshan M, Alam MT, Vinayak S, Bora H, Tyagi RK, Alam MS, Choudhary V, Mittra P, Lumb V, Bharti PK, Udhayakumar V, Singh N, Jain V, Singh PP, Sharma YD. Genetic variation in the Plasmodium falciparum circumsporozoite protein in India and its relevance to RTS,S malaria vaccine. PLoS One 2012; 7:e43430. [PMID: 22912873 PMCID: PMC3422267 DOI: 10.1371/journal.pone.0043430] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/20/2012] [Indexed: 11/19/2022] Open
Abstract
RTS,S is the most advanced malaria vaccine candidate, currently under phase-III clinical trials in Africa. This Plasmodium falciparum vaccine contains part of the central repeat region and the complete C-terminal T cell epitope region (Th2R and Th3R) of the circumsporozoite protein (CSP). Since naturally occurring polymorphisms at the vaccine candidate loci are critical determinants of the protective efficacy of the vaccines, it is imperative to investigate these polymorphisms in field isolates. In this study we have investigated the genetic diversity at the central repeat, C-terminal T cell epitope (Th2R and Th3R) and N-terminal T cell epitope regions of the CSP, in P. falciparum isolates from Madhya Pradesh state of India. These isolates were collected through a 5-year prospective study aimed to develop a well-characterized field-site for the future evaluation of malaria vaccine in India. Our results revealed that the central repeat (63 haplotypes, n = 161) and C-terminal Th2R/Th3R epitope (24 haplotypes, n = 179) regions were highly polymorphic, whereas N-terminal non-repeat region was less polymorphic (5 haplotypes, n = 161) in this population. We did not find any evidence of the role of positive natural selection in maintaining the genetic diversity at the Th2R/Th3R regions of CSP. Comparative analysis of the Th2R/Th3R sequences from this study to the global isolates (n = 1160) retrieved from the GenBank database revealed two important points. First, the majority of the sequences (∼61%, n = 179) from this study were identical to the Dd2/Indochina type, which is also the predominant Th2R/Th3R haplotype in Asia (∼59%, n = 974). Second, the Th2R/Th3R sequences in Asia, South America and Africa are geographically distinct with little allele sharing between continents. In conclusion, this study provides an insight on the existing polymorphisms in the CSP in a parasite population from India that could potentially influence the efficacy of RTS,S vaccine in this region.
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Affiliation(s)
- Mohammad Zeeshan
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Mohammad Tauqeer Alam
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Sumiti Vinayak
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Hema Bora
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Rupesh Kumar Tyagi
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Mohd Shoeb Alam
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Vandana Choudhary
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Pooja Mittra
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Vanshika Lumb
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Neeru Singh
- Regional Medical Research Centre for Tribals, Jabalpur, Madhya Pradesh, India
| | - Vidhan Jain
- Regional Medical Research Centre for Tribals, Jabalpur, Madhya Pradesh, India
| | | | - Yagya Dutta Sharma
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
- * E-mail:
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Yadava A, Nurmukhambetova S, Pichugin AV, Lumsden JM. Cross-species immunity following immunization with a circumsporozoite protein-based vaccine for malaria. J Infect Dis 2012; 205:1456-63. [PMID: 22457289 DOI: 10.1093/infdis/jis220] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Malaria continues to be a major public health concern, and there are concerted efforts to eliminate it. The quest for a vaccine remains a top priority, and vaccines based on the circumsporozoite protein (CSP) are among the lead candidates, with the RTS,S vaccine currently undergoing phase 3 testing in Africa. Previous studies have reported anti-CSP antibody-mediated enhancement of in vitro invasion of homologous sporozoites. This effect has been shown to be concentration dependent; high-level antibodies are inhibitory, whereas low-level antibodies lead to enhancement of invasion. Nondominant shared epitopes may lead to the generation of low titers of cross-reactive antibodies that may prove to be detrimental. We report cross-species recognition of Plasmodium falciparum and Plasmodium berghei sporozoites by anti-Plasmodium vivax CSP serum samples. In addition, we report that vaccination of mice with VMP001, a P. vivax CSP vaccine candidate, reduces, not enhances, P. berghei infection in mice.
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Affiliation(s)
- Anjali Yadava
- Malaria Vaccine Branch, United States Military Malaria Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910, USA.
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Affiliation(s)
- Suzanne Moore Shepherd
- Department of Emergency Medicine, PENN Travel Medicine, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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Abstract
There is no licenced vaccine against any human parasitic disease and Plasmodium falciparum malaria, a major cause of infectious mortality, presents a great challenge to vaccine developers. This has led to the assessment of a wide variety of approaches to malaria vaccine design and development, assisted by the availability of a safe challenge model for small-scale efficacy testing of vaccine candidates. Malaria vaccine development has been at the forefront of assessing many new vaccine technologies including novel adjuvants, vectored prime-boost regimes and the concept of community vaccination to block malaria transmission. Most current vaccine candidates target a single stage of the parasite's life cycle and vaccines against the early pre-erythrocytic stages have shown most success. A protein in adjuvant vaccine, working through antibodies against sporozoites, and viral vector vaccines targeting the intracellular liver-stage parasite with cellular immunity show partial efficacy in humans, and the anti-sporozoite vaccine is currently in phase III trials. However, a more effective malaria vaccine suitable for widespread cost-effective deployment is likely to require a multi-component vaccine targeting more than one life cycle stage. The most attractive near-term approach to develop such a product is to combine existing partially effective pre-erythrocytic vaccine candidates.
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Affiliation(s)
- Adrian V S Hill
- The Jenner Institute, University of Oxford, Old Road Campus Research Building, Oxford OX37DQ, UK.
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Agnandji ST, Lell B, Soulanoudjingar SS, Fernandes JF, Abossolo BP, Conzelmann C, Methogo BGNO, Doucka Y, Flamen A, Mordmüller B, Issifou S, Kremsner PG, Sacarlal J, Aide P, Lanaspa M, Aponte JJ, Nhamuave A, Quelhas D, Bassat Q, Mandjate S, Macete E, Alonso P, Abdulla S, Salim N, Juma O, Shomari M, Shubis K, Machera F, Hamad AS, Minja R, Mtoro A, Sykes A, Ahmed S, Urassa AM, Ali AM, Mwangoka G, Tanner M, Tinto H, D'Alessandro U, Sorgho H, Valea I, Tahita MC, Kaboré W, Ouédraogo S, Sandrine Y, Guiguemdé RT, Ouédraogo JB, Hamel MJ, Kariuki S, Odero C, Oneko M, Otieno K, Awino N, Omoto J, Williamson J, Muturi-Kioi V, Laserson KF, Slutsker L, Otieno W, Otieno L, Nekoye O, Gondi S, Otieno A, Ogutu B, Wasuna R, Owira V, Jones D, Onyango AA, Njuguna P, Chilengi R, Akoo P, Kerubo C, Gitaka J, Maingi C, Lang T, Olotu A, Tsofa B, Bejon P, Peshu N, Marsh K, Owusu-Agyei S, Asante KP, Osei-Kwakye K, Boahen O, Ayamba S, Kayan K, Owusu-Ofori R, Dosoo D, Asante I, Adjei G, Adjei G, Chandramohan D, Greenwood B, Lusingu J, Gesase S, Malabeja A, Abdul O, Kilavo H, Mahende C, Liheluka E, Lemnge M, Theander T, Drakeley C, Ansong D, Agbenyega T, Adjei S, Boateng HO, Rettig T, Bawa J, Sylverken J, Sambian D, Agyekum A, Owusu L, Martinson F, Hoffman I, Mvalo T, Kamthunzi P, Nkomo R, Msika A, Jumbe A, Chome N, Nyakuipa D, Chintedza J, Ballou WR, Bruls M, Cohen J, Guerra Y, Jongert E, Lapierre D, Leach A, Lievens M, Ofori-Anyinam O, Vekemans J, Carter T, Leboulleux D, Loucq C, Radford A, Savarese B, Schellenberg D, Sillman M, Vansadia P. First results of phase 3 trial of RTS,S/AS01 malaria vaccine in African children. N Engl J Med 2011; 365:1863-75. [PMID: 22007715 DOI: 10.1056/nejmoa1102287] [Citation(s) in RCA: 613] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND An ongoing phase 3 study of the efficacy, safety, and immunogenicity of candidate malaria vaccine RTS,S/AS01 is being conducted in seven African countries. METHODS From March 2009 through January 2011, we enrolled 15,460 children in two age categories--6 to 12 weeks of age and 5 to 17 months of age--for vaccination with either RTS,S/AS01 or a non-malaria comparator vaccine. The primary end point of the analysis was vaccine efficacy against clinical malaria during the 12 months after vaccination in the first 6000 children 5 to 17 months of age at enrollment who received all three doses of vaccine according to protocol. After 250 children had an episode of severe malaria, we evaluated vaccine efficacy against severe malaria in both age categories. RESULTS In the 14 months after the first dose of vaccine, the incidence of first episodes of clinical malaria in the first 6000 children in the older age category was 0.32 episodes per person-year in the RTS,S/AS01 group and 0.55 episodes per person-year in the control group, for an efficacy of 50.4% (95% confidence interval [CI], 45.8 to 54.6) in the intention-to-treat population and 55.8% (97.5% CI, 50.6 to 60.4) in the per-protocol population. Vaccine efficacy against severe malaria was 45.1% (95% CI, 23.8 to 60.5) in the intention-to-treat population and 47.3% (95% CI, 22.4 to 64.2) in the per-protocol population. Vaccine efficacy against severe malaria in the combined age categories was 34.8% (95% CI, 16.2 to 49.2) in the per-protocol population during an average follow-up of 11 months. Serious adverse events occurred with a similar frequency in the two study groups. Among children in the older age category, the rate of generalized convulsive seizures after RTS,S/AS01 vaccination was 1.04 per 1000 doses (95% CI, 0.62 to 1.64). CONCLUSIONS The RTS,S/AS01 vaccine provided protection against both clinical and severe malaria in African children. (Funded by GlaxoSmithKline Biologicals and the PATH Malaria Vaccine Initiative; RTS,S ClinicalTrials.gov number, NCT00866619 .).
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Campo JJ, Dobaño C, Sacarlal J, Guinovart C, Mayor A, Angov E, Dutta S, Chitnis C, Macete E, Aponte JJ, Alonso PL. Impact of the RTS,S malaria vaccine candidate on naturally acquired antibody responses to multiple asexual blood stage antigens. PLoS One 2011; 6:e25779. [PMID: 22022448 PMCID: PMC3192128 DOI: 10.1371/journal.pone.0025779] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2011] [Accepted: 09/09/2011] [Indexed: 11/18/2022] Open
Abstract
Background Partial protective efficacy lasting up to 43 months after vaccination with the RTS,S malaria vaccine has been reported in one cohort (C1) of a Phase IIb trial in Mozambique, but waning efficacy was observed in a smaller contemporaneous cohort (C2). We hypothesized that low dose exposure to asexual stage parasites resulting from partial pre-erythrocytic protection afforded by RTS,S may contribute to long-term vaccine efficacy to clinical disease, which was not observed in C2 due to intense active detection of infection and treatment. Methodology/Principal Findings Serum collected 6 months post-vaccination was screened for antibodies to asexual blood stage antigens AMA-1, MSP-142, EBA-175, DBL-α and variant surface antigens of the R29 laboratory strain (VSAR29). Effect of IgG on the prospective hazard of clinical malaria was estimated. No difference was observed in antibody levels between RTS,S and control vaccine when all children aged 1–4 years at enrollment in both C1 and C2 were analyzed together, and no effects were observed between cohort and vaccine group. RTS,S-vaccinated children <2 years of age at enrollment had lower levels of IgG for AMA-1 and MSP-142 (p<0.01, all antigens), while no differences were observed in children ≥2 years. Lower risk of clinical malaria was associated with high IgG to EBA-175 and VSAR29 in C2 only (Hazard Ratio [HR]: 0.76, 95% CI 0.66–0.88; HR: 0.75, 95% CI 0.62–0.92, respectively). Conclusions Vaccination with RTS,S modestly reduces anti-AMA-1 and anti-MSP-1 antibodies in very young children. However, for antigens associated with lower risk of clinical malaria, there were no vaccine group or cohort-specific effects, and age did not influence antibody levels between treatment groups for these antigens. The antigens tested do not explain the difference in protective efficacy in C1 and C2. Other less-characterized antigens or VSA may be important to protection. Trial Registration ClinicalTrials.gov NCT00197041
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Affiliation(s)
- Joseph J. Campo
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic / Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Carlota Dobaño
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic / Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
- * E-mail:
| | - Jahit Sacarlal
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Caterina Guinovart
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic / Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Alfredo Mayor
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic / Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Evelina Angov
- United States Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Sheetij Dutta
- United States Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Chetan Chitnis
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Eusebio Macete
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - John J. Aponte
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic / Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
| | - Pedro L. Alonso
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clinic / Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça, Manhiça, Mozambique
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Butler NS, Schmidt NW, Vaughan AM, Aly AS, Kappe SHI, Harty JT. Superior antimalarial immunity after vaccination with late liver stage-arresting genetically attenuated parasites. Cell Host Microbe 2011; 9:451-62. [PMID: 21669394 DOI: 10.1016/j.chom.2011.05.008] [Citation(s) in RCA: 182] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 04/20/2011] [Accepted: 05/31/2011] [Indexed: 10/18/2022]
Abstract
While subunit vaccines have shown partial efficacy in clinical trials, radiation-attenuated sporozoites (RAS) remain the "gold standard" for sterilizing protection against Plasmodium infection in human vaccinees. The variability in immunogenicity and replication introduced by the extensive, random DNA damage necessary to generate RAS could be overcome by genetically attenuated parasites (GAP) designed via gene deletion to arrest at defined points during liver-stage development. Here, we demonstrate the principle that late liver stage-arresting GAP induce larger and broader CD8 T cell responses that provide superior protection in inbred and outbred mice compared to RAS or early-arresting GAP immunizations. Late liver stage-arresting GAP also engender high levels of cross-stage and cross-species protection and complete protection when administered by translationally relevant intradermal or subcutaneous routes. Collectively, our results underscore the potential utility of late liver stage-arresting GAP as broadly protective next-generation live-attenuated malaria vaccines and support their potential as a powerful model for identifying antigens to generate cross-stage protection.
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Affiliation(s)
- Noah S Butler
- Department of Microbiology, University of Iowa, 3-512 Bowen Science Building, Iowa City, IA 52242, USA
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30
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Plasmodium falciparum serine repeat antigen 5 (SE36) as a malaria vaccine candidate. Vaccine 2011; 29:5837-45. [DOI: 10.1016/j.vaccine.2011.06.052] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 05/31/2011] [Accepted: 06/14/2011] [Indexed: 12/29/2022]
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Pollock T, Leitao R, Galan-Rodriguez C, Wong KA, Rodriguez A. Daily Plasmodium yoelii infective mosquito bites do not generate protection or suppress previous immunity against the liver stage. Malar J 2011; 10:97. [PMID: 21501513 PMCID: PMC3102649 DOI: 10.1186/1475-2875-10-97] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 04/18/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human populations that are naturally subjected to Plasmodium infection do not acquire complete protection against the liver stage of this parasite despite prolonged and frequent exposure. However, sterile immunity against Plasmodium liver stage can be achieved after repeated exposure to radiation attenuated sporozoites. The reasons for this different response remain largely unknown, but a suppressive effect of blood stage Plasmodium infection has been proposed as a cause for the lack of liver stage protection. METHODS Using Plasmodium yoelii 17XNL, the response generated in mice subjected to daily infective bites from normal or irradiated mosquitoes was compared. The effect of daily-infected mosquito bites on mice that were previously immunized against P. yoelii liver stage was also studied. RESULTS It was observed that while the bites of normal infected mosquitoes do not generate strong antibody responses and protection, the bites of irradiated mosquitoes result in high levels of anti-sporozoite antibodies and protection against liver stage Plasmodium infection. Exposure to daily infected mosquito bites did not eliminate the protection acquired previously with a experimental liver stage vaccine. CONCLUSIONS Liver stage immunity generated by irradiated versus normal P. yoelii infected mosquitoes is essentially different, probably because of the blood stage infection that follows normal mosquito bites, but not irradiated. While infective mosquito bites do not induce a protective liver stage response, they also do not interfere with previously acquired liver stage protective responses, even if they induce a complete blood stage infection. Considering that the recently generated anti-malaria vaccines induce only partial protection against infection, it is encouraging that, at least in mouse models, immunity is not negatively affected by subsequent exposure and infection with the parasite.
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Affiliation(s)
- Tzvi Pollock
- Department of Microbiology, Division of Medical Parasitology, New York University School of Medicine, New York, NY 10010, USA
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Clark K, Cavicchi J, Jensen K, Fitzgerald R, Bennett A, Kowalski SP. Patent data mining: a tool for accelerating HIV vaccine innovation. Vaccine 2011; 29:4086-93. [PMID: 21496469 DOI: 10.1016/j.vaccine.2011.03.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 03/08/2011] [Accepted: 03/17/2011] [Indexed: 11/29/2022]
Abstract
Global access to advanced vaccine technologies is challenged by the interrelated components of intellectual property (IP) management strategies, technology transfer (legal and technical) capabilities and the capacity necessary for accelerating R&D, commercialization and delivery of vaccines. Due to a negative association with the management of IP, patents are often overlooked as a vast resource of freely available, information akin to scientific journals as well as business and technological information and trends fundamental for formulating policies and IP management strategies. Therefore, a fundamental step towards facilitating global vaccine access will be the assembly, organization and analysis of patent landscapes, to identify the amount of patenting, ownership (assignees) and fields of technology covered. This is critical for making informed decisions (e.g., identifying licensees, building research and product development collaborations, and ascertaining freedom to operate). Such information is of particular interest to the HIV vaccine community where the HIV Vaccine Enterprise, have voiced concern that IP rights (particularly patents and trade secrets) may prevent data and materials sharing, delaying progress in research and development of a HIV vaccine. We have compiled and analyzed a representative HIV vaccine patent landscape for a prime-boost, DNA/adenoviral vaccine platform, as an example for identifying obstacles, maximizing opportunities and making informed IP management strategy decisions towards the development and deployment of an efficacious HIV vaccine.
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Affiliation(s)
- K Clark
- PIPRA, University of California, Davis, CA 95616, USA.
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