1
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Patel PN, Diouf A, Dickey TH, Tang WK, Hopp CS, Traore B, Long CA, Miura K, Crompton PD, Tolia NH. A strain-transcending anti-AMA1 human monoclonal antibody neutralizes malaria parasites independent of direct RON2L receptor blockade. Cell Rep Med 2025; 6:101985. [PMID: 40020675 PMCID: PMC11970402 DOI: 10.1016/j.xcrm.2025.101985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2024] [Revised: 01/06/2025] [Accepted: 01/31/2025] [Indexed: 03/03/2025]
Abstract
Plasmodium falciparum apical membrane antigen 1 (AMA1) binds a loop in rhoptry neck protein 2 (RON2L) during red cell invasion and is a target for vaccines and therapeutic antibodies against malaria. Here, we report a panel of AMA1-specific naturally acquired human monoclonal antibodies (hmAbs) derived from individuals living in malaria-endemic regions. Two neutralizing hmAbs engage AMA1 independent of the RON2L-binding site. The hmAb 75B10 demonstrates potent strain-transcending neutralization that is independent of RON2L blockade, emphasizing that epitopes outside the RON2L-binding site elicit broad protection against variant parasite strains. The combination of these hmAbs synergistically enhances parasite neutralization. Vaccination with a structure-based design (SBD1) that mimics the AMA1-RON2L complex elicited antibodies similar to the two neutralizing hmAbs connecting vaccination to naturally acquired immunity in humans. The structural definition of a strain-transcending epitope on AMA1 targeted by naturally acquired hmAb establishes paradigms for developing AMA1-based vaccines and therapeutic antibodies.
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Affiliation(s)
- Palak N Patel
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Thayne H Dickey
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Wai Kwan Tang
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Christine S Hopp
- Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Boubacar Traore
- Malaria Research and Training Centre, Mali International Center of Excellence in Research, University of Sciences, Techniques and Technologies of Bamako, Point G, Bamako 1805, Mali
| | - Carole A Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Peter D Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Niraj H Tolia
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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2
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Tay MZ, Tang W, Lee WC, Ong ASM, Novera W, Malleret B, Carissimo G, Chacko AM, El-Sahili A, Lescar J, Fan Y, McGready RM, Chu CS, Chan JKY, Ng LFP, Russell B, Nosten F, Rénia L. Functional and Immunologic Mapping of Domains of the Reticulocyte-Binding Protein Plasmodium vivax PvRBP2a. J Infect Dis 2024; 230:e737-e742. [PMID: 38441336 PMCID: PMC11420707 DOI: 10.1093/infdis/jiae111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 03/03/2024] [Indexed: 09/25/2024] Open
Abstract
We previously described a novel Plasmodium vivax invasion mechanism into human reticulocytes via the PvRBP2a-CD98 receptor-ligand pair. Using linear epitope mapping, we assessed the PvRBP2a epitopes involved in CD98 binding and recognized by antibodies from patients who were infected. We identified 2 epitope clusters mediating PvRBP2a-CD98 interaction. Cluster B (PvRBP2a431-448, TAALKEKGKLLANLYNKL) was the target of antibody responses in humans infected by P vivax. Peptides from each cluster were able to prevent live parasite invasion of human reticulocytes. These results provide new insights for development of a malaria blood-stage vaccine against P vivax.
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Affiliation(s)
- Matthew Zirui Tay
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
| | - Weiyi Tang
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
| | - Wenn-Chyau Lee
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur, Malaysia
| | - Alice Soh Meoy Ong
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
| | - Wisna Novera
- Laboratory for Translational and Molecular Imaging, Cancer and Stem Cell Biology Programme, Duke-NUS Medical School
| | - Benoît Malleret
- Department of Microbiology and Immunology, Immunology Translational Research Programme
| | - Guillaume Carissimo
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System
| | - Ann-Marie Chacko
- Laboratory for Translational and Molecular Imaging, Cancer and Stem Cell Biology Programme, Duke-NUS Medical School
| | - Abbas El-Sahili
- NTU Institute for Structural Biology, Nanyang Technological University
| | - Julien Lescar
- NTU Institute for Structural Biology, Nanyang Technological University
| | - Yiping Fan
- Department of Reproductive Medicine, KK Women's and Children's Hospital
- Experimental Fetal Medicine Group, Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore
- Academic Clinical Program in Obstetrics and Gynaecology, Duke-NUS Medical School, Singapore
| | - Rose M McGready
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Cindy S Chu
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Jerry Kok Yen Chan
- Department of Reproductive Medicine, KK Women's and Children's Hospital
- Experimental Fetal Medicine Group, Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University of Singapore
- Academic Clinical Program in Obstetrics and Gynaecology, Duke-NUS Medical School, Singapore
| | - Lisa F P Ng
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Bruce Russell
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Laurent Rénia
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
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3
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Nayeri T, Sarvi S, Daryani A. Effective factors in the pathogenesis of Toxoplasmagondii. Heliyon 2024; 10:e31558. [PMID: 38818168 PMCID: PMC11137575 DOI: 10.1016/j.heliyon.2024.e31558] [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: 01/03/2023] [Revised: 05/11/2024] [Accepted: 05/17/2024] [Indexed: 06/01/2024] Open
Abstract
Toxoplasma gondii (T. gondii) is a cosmopolitan protozoan parasite in humans and animals. It infects about 30 % of the human population worldwide and causes potentially fatal diseases in immunocompromised hosts and neonates. For this study, five English-language databases (ScienceDirect, ProQuest, Web of Science, PubMed, and Scopus) and the internet search engine Google Scholar were searched. This review was accomplished to draw a global perspective of what is known about the pathogenesis of T. gondii and various factors affecting it. Virulence and immune responses can influence the mechanisms of parasite pathogenesis and these factors are in turn influenced by other factors. In addition to the host's genetic background, the type of Toxoplasma strain, the routes of transmission of infection, the number of passages, and different phases of parasite life affect virulence. The identification of virulence factors of the parasite could provide promising insights into the pathogenesis of this parasite. The results of this study can be an incentive to conduct more intensive research to design and develop new anti-Toxoplasma agents (drugs and vaccines) to treat or prevent this infection. In addition, further studies are needed to better understand the key agents in the pathogenesis of T. gondii.
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Affiliation(s)
- Tooran Nayeri
- Infectious and Tropical Diseases Research Center, Dezful University of Medical Sciences, Dezful, Iran
- Student Research Committee, Mazandaran University of Medical Sciences, Sari, Iran
| | - Shahabeddin Sarvi
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ahmad Daryani
- Department of Parasitology, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
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4
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Kim MJ, Chu KB, Yoon KW, Kang HJ, Lee DH, Moon EK, Quan FS. Virus-like particles expressing microneme-associated antigen of Plasmodium berghei confer better protection than those expressing apical membrane antigen 1. PARASITES, HOSTS AND DISEASES 2024; 62:193-204. [PMID: 38835260 PMCID: PMC11150920 DOI: 10.3347/phd.24017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 04/18/2024] [Indexed: 06/06/2024]
Abstract
Malaria is a global disease affecting a large portion of the world's population. Although vaccines have recently become available, their efficacies are suboptimal. We generated virus-like particles (VLPs) that expressed either apical membrane antigen 1 (AMA1) or microneme-associated antigen (MIC) of Plasmodium berghei and compared their efficacy in BALB/c mice. We found that immune sera acquired from AMA1 VLP- or MIC VLP-immunized mice specifically interacted with the antigen of choice and the whole P. berghei lysate antigen, indicating that the antibodies were highly parasite-specific. Both VLP vaccines significantly enhanced germinal center B cell frequencies in the inguinal lymph nodes of mice compared with the control, but only the mice that received MIC VLPs showed significantly enhanced CD4+ T cell responses in the blood following P. berghei challenge infection. AMA1 and MIC VLPs significantly suppressed TNF-α and interleukin-10 production but had a negligible effect on interferon-γ. Both VLPs prevented excessive parasitemia buildup in immunized mice, although parasite burden reduction induced by MIC VLPs was slightly more effective than that induced by AMA1. Both VLPs were equally effective at preventing body weight loss. Our findings demonstrated that the MIC VLP was an effective inducer of protection against murine experimental malaria and should be the focus of further development.
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Affiliation(s)
- Min-Ju Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447,
Korea
| | - Ki Back Chu
- Department of Parasitology, Inje University College of Medicine, Busan 47392,
Korea
- Department of Infectious Disease and Malaria, Paik Institute of Clinical Research, Inje University, Busan 47392,
Korea
| | - Keon-Woong Yoon
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447,
Korea
| | - Hae-Ji Kang
- Department of Microbiology, Dongguk University College of Medicine, Gyeongju 38066,
Korea
| | - Dong-Hun Lee
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447,
Korea
| | - Eun-Kyung Moon
- Department of Medical Zoology, Kyung Hee University School of Medicine, Seoul 02447,
Korea
| | - Fu-Shi Quan
- Department of Medical Zoology, Kyung Hee University School of Medicine, Seoul 02447,
Korea
- Medical Research Center for Bioreaction to Reactive Oxygen Species and Biomedical Science Institute, School of Medicine, Graduate School, Kyung Hee University, Seoul 02447,
Korea
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5
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Rodríguez-Obediente K, Yepes-Pérez Y, Benavides-Ortiz D, Díaz-Arévalo D, Reyes C, Arévalo-Pinzón G, Patarroyo MA. Invasion-inhibitory peptides chosen by natural selection analysis as an antimalarial strategy. Mol Immunol 2023; 163:86-103. [PMID: 37769577 DOI: 10.1016/j.molimm.2023.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 09/06/2023] [Accepted: 09/14/2023] [Indexed: 10/03/2023]
Abstract
Plasmodium vivax's biological complexity has restricted in vitro culture development for characterising antigens involved in erythrocyte invasion and their immunological relevance. The murine model is proposed as a suitable alternative in the search for therapeutic candidates since Plasmodium yoelii uses homologous proteins for its invasion. The AMA-1 protein is essential for parasite invasion of erythrocytes as it is considered an important target for infection control. This study has focused on functional PyAMA-1 peptides involved in host-pathogen interaction; the protein is located in regions under negative selection as determined by bioinformatics analysis. It was found that pyama1 has two highly conserved regions amongst species (>70%) under negative selection. Fourteen synthetic peptides spanning both conserved regions were evaluated; 5 PyAMA-1 peptides having high specific binding (HABP) to murine erythrocytes were identified. The parasite's invasion inhibition capability was analysed through in vitro assays, suggesting that peptides 42681 (43-ENTERSIKLINPWDKYMEKY-62), 42903 (206-RYSSNDANNENQPFSFTPEK-225) and 42904 (221-FTPEKIENYKDLSYLTKNLR-240) had greater than 50% inhibition profile and restricted P. yoelii intra-erythrocyte development. This work proposes that the screening of conserved HABPs under negative selective pressure might be good candidates for developing a synthetic anti-malarial vaccine since they share functionally-relevant characteristics, such as interspecies conservation, specific RBC binding profile, invasion and parasite development inhibition capability, and the predicted B-epitopes within were recognised by sera obtained from experimentally-infected mice.
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Affiliation(s)
- Kewin Rodríguez-Obediente
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia; MSc programme in Microbiology, Biotechnology Institute, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Yoelis Yepes-Pérez
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
| | - Daniel Benavides-Ortiz
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia; School of Health Sciences, Universidad Colegio Mayor de Cundinamarca, Bogotá, Colombia
| | - Diana Díaz-Arévalo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia; Animal Science Faculty, Universidad de Ciencias Aplicadas y Ambientales (U.D.C.A), Bogotá, Colombia
| | - César Reyes
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
| | - Gabriela Arévalo-Pinzón
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia; Microbiology Department, Science Faculty, Pontificia Universidad Javeriana, Bogotá, Colombia
| | - Manuel Alfonso Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia; Microbiology Department, Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia.
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6
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Patel PN, Dickey TH, Diouf A, Salinas ND, McAleese H, Ouahes T, Long CA, Miura K, Lambert LE, Tolia NH. Structure-based design of a strain transcending AMA1-RON2L malaria vaccine. Nat Commun 2023; 14:5345. [PMID: 37660103 PMCID: PMC10475129 DOI: 10.1038/s41467-023-40878-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 08/14/2023] [Indexed: 09/04/2023] Open
Abstract
Apical membrane antigen 1 (AMA1) is a key malaria vaccine candidate and target of neutralizing antibodies. AMA1 binds to a loop in rhoptry neck protein 2 (RON2L) to form the moving junction during parasite invasion of host cells, and this complex is conserved among apicomplexan parasites. AMA1-RON2L complex immunization achieves higher growth inhibitory activity than AMA1 alone and protects mice against Plasmodium yoelii challenge. Here, three single-component AMA1-RON2L immunogens were designed that retain the structure of the two-component AMA1-RON2L complex: one structure-based design (SBD1) and two insertion fusions. All immunogens elicited high antibody titers with potent growth inhibitory activity, yet these antibodies did not block RON2L binding to AMA1. The SBD1 immunogen induced significantly more potent strain-transcending neutralizing antibody responses against diverse strains of Plasmodium falciparum than AMA1 or AMA1-RON2L complex vaccination. This indicates that SBD1 directs neutralizing antibody responses to strain-transcending epitopes in AMA1 that are independent of RON2L binding. This work underscores the importance of neutralization mechanisms that are distinct from RON2 blockade. The stable single-component SBD1 immunogen elicits potent strain-transcending protection that may drive the development of next-generation vaccines for improved malaria and apicomplexan parasite control.
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Affiliation(s)
- Palak N Patel
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thayne H Dickey
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Nichole D Salinas
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Holly McAleese
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Tarik Ouahes
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Carole A Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Lynn E Lambert
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Niraj H Tolia
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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7
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Cutts JC, O'Flaherty K, Zaloumis SG, Ashley EA, Chan JA, Onyamboko MA, Fanello C, Dondorp AM, Day NP, Phyo AP, Dhorda M, Imwong M, Fairhurst RM, Lim P, Amaratunga C, Pukrittayakamee S, Hien TT, Htut Y, Mayxay M, Abdul Faiz M, Takashima E, Tsuboi T, Beeson JG, Nosten F, Simpson JA, White NJ, Fowkes FJI. Comparison of antibody responses and parasite clearance in artemisinin therapeutic efficacy studies in Democratic Republic of Congo and Asia. J Infect Dis 2022; 226:324-331. [PMID: 35703955 PMCID: PMC9400417 DOI: 10.1093/infdis/jiac232] [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: 02/10/2022] [Accepted: 06/12/2022] [Indexed: 12/05/2022] Open
Abstract
Background Understanding the effect of immunity on Plasmodium falciparum clearance is essential for interpreting therapeutic efficacy studies designed to monitor emergence of artemisinin drug resistance. In low-transmission areas of Southeast Asia, where resistance has emerged, P. falciparum antibodies confound parasite clearance measures. However, variation in naturally acquired antibodies across Asian and sub-Saharan African epidemiological contexts and their impact on parasite clearance re yet to be quantified. Methods In an artemisinin therapeutic efficacy study, antibodies to 12 pre-erythrocytic and erythrocytic P. falciparum antigens were measured in 118 children with uncomplicated P. falciparum malaria in the Democratic Republic of Congo (DRC) and compared with responses in patients from Asian sites, described elsewhere. Results Parasite clearance half-life was shorter in DRC patients (median, 2 hours) compared with most Asian sites (median, 2–7 hours), but P. falciparum antibody levels and seroprevalences were similar. There was no evidence for an association between antibody seropositivity and parasite clearance half-life (mean difference between seronegative and seropositive, −0.14 to +0.40 hour) in DRC patients. Conclusions In DRC, where artemisinin remains highly effective, the substantially shorter parasite clearance time compared with Asia was not explained by differences in the P. falciparum antibody responses studied.
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Affiliation(s)
- Julia C Cutts
- Burnet Institute, Melbourne, Victoria 3004, Australia.,Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria 3000, Australia
| | | | - Sophie G Zaloumis
- Centre for Epidemiology and Biostatistics, Melbourne, School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Elizabeth A Ashley
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom.,Lao-Oxford-Mahosot Hospital-Wellcome Trust-Research Unit, Mahosot Hospital, Vientiane, Lao PDR
| | - Jo Anne Chan
- Burnet Institute, Melbourne, Victoria 3004, Australia.,Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria 3000, Australia.,Department of Immunology, Monash University, Melbourne Australia
| | - Marie A Onyamboko
- Kinshasa School of Public Health, Kinshasa, Democratic Republic of Congo
| | - Caterina Fanello
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom.,Kinshasa School of Public Health, Kinshasa, Democratic Republic of Congo
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom
| | - Nicholas P Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom
| | | | - Mehul Dhorda
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom.,Worldwide Antimalarial Resistance Network, Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom
| | - Mallika Imwong
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Pharath Lim
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Chanaki Amaratunga
- Worldwide Antimalarial Resistance Network, Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom
| | | | - Tran Tinh Hien
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Ye Htut
- Department of Medical Research, Yangon, Myanmar
| | - Mayfong Mayxay
- Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom.,Institute of Research and Education Development, University of Health Sciences, Vientiane, Lao PDR.,Lao-Oxford-Mahosot Hospital-Wellcome Trust-Research Unit, Mahosot Hospital, Vientiane, Lao PDR
| | - M Abdul Faiz
- Malaria Research Group & Dev Care Foundation, Chittagong, Bangladesh
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - James G Beeson
- Burnet Institute, Melbourne, Victoria 3004, Australia.,Department of Infectious Diseases, University of Melbourne, at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria 3000, Australia.,Department of Immunology, Monash University, Melbourne Australia
| | - Francois Nosten
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom.,Shoklo Malaria Research Unit, Mae Sot, Thailand
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne, School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, United Kingdom
| | - Freya J I Fowkes
- Burnet Institute, Melbourne, Victoria 3004, Australia.,Centre for Epidemiology and Biostatistics, Melbourne, School of Population and Global Health, The University of Melbourne, Melbourne, Australia.,Department of Infectious Diseases and Department of Epidemiology and Preventative Medicine, Monash University, Melbourne, Australia
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8
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Smith EC, Limbach KJ, Rangel N, Oda K, Bolton JS, Du M, Gowda K, Wang J, Moch JK, Sonawane S, Velasco R, Belmonte A, Danner R, Lumsden JM, Patterson NB, Sedegah M, Hollingdale MR, Richie TL, Sacci JB, Villasante ED, Aguiar JC. Novel malaria antigen Plasmodium yoelii E140 induces antibody-mediated sterile protection in mice against malaria challenge. PLoS One 2020; 15:e0232234. [PMID: 32407410 PMCID: PMC7224506 DOI: 10.1371/journal.pone.0232234] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 04/09/2020] [Indexed: 11/18/2022] Open
Abstract
Only a small fraction of the antigens expressed by malaria parasites have been evaluated as vaccine candidates. A successful malaria subunit vaccine will likely require multiple antigenic targets to achieve broad protection with high protective efficacy. Here we describe protective efficacy of a novel antigen, Plasmodium yoelii (Py) E140 (PyE140), evaluated against P. yoelii challenge of mice. Vaccines targeting PyE140 reproducibly induced up to 100% sterile protection in both inbred and outbred murine challenge models. Although PyE140 immunization induced high frequency and multifunctional CD8+ T cell responses, as well as CD4+ T cell responses, protection was mediated by PyE140 antibodies acting against blood stage parasites. Protection in mice was long-lasting with up to 100% sterile protection at twelve weeks post-immunization and durable high titer anti-PyE140 antibodies. The E140 antigen is expressed in all Plasmodium species, is highly conserved in both P. falciparum lab-adapted strains and endemic circulating parasites, and is thus a promising lead vaccine candidate for future evaluation against human malaria parasite species.
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Affiliation(s)
- Emily C. Smith
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Keith J. Limbach
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Nonenipha Rangel
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- CAMRIS International, Bethesda, Maryland, United States of America
| | - Kyosuke Oda
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- CAMRIS International, Bethesda, Maryland, United States of America
| | - Jessica S. Bolton
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Mengyan Du
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Kalpana Gowda
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Jianyang Wang
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- CAMRIS International, Bethesda, Maryland, United States of America
| | - J. Kathleen Moch
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Sharvari Sonawane
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Rachel Velasco
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Arnel Belmonte
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Rebecca Danner
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Joanne M. Lumsden
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Noelle B. Patterson
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Martha Sedegah
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Michael R. Hollingdale
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc. (HJF), Bethesda, Maryland, United States of America
| | - Thomas L. Richie
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - John B. Sacci
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Eileen D. Villasante
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Joao C. Aguiar
- Malaria Department, Naval Medical Research Center, Silver Spring, Maryland, United States of America
- CAMRIS International, Bethesda, Maryland, United States of America
- * E-mail:
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9
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Kale S, Yadav CP, Rao PN, Shalini S, Eapen A, Srivasatava HC, Sharma SK, Pande V, Carlton JM, Singh OP, Mallick PK. Antibody responses within two leading Plasmodium vivax vaccine candidate antigens in three geographically diverse malaria-endemic regions of India. Malar J 2019; 18:425. [PMID: 31842894 PMCID: PMC6916228 DOI: 10.1186/s12936-019-3066-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 12/08/2019] [Indexed: 01/28/2023] Open
Abstract
Background Identifying highly immunogenic blood stage antigens which can work as target for naturally acquired antibodies in different eco-epidemiological settings is an important step for designing malaria vaccine. Blood stage proteins of Plasmodium vivax, apical membrane antigen-1 (PvAMA-1) and 19 kDa fragment of merozoite surface protein (PvMSP-119) are such promising vaccine candidate antigens. This study determined the naturally-acquired antibody response to PvAMA-1 and PvMSP-119 antigens in individuals living in three geographically diverse malaria endemic regions of India. Methods A total of 234 blood samples were collected from individuals living in three different eco-epidemiological settings, Chennai, Nadiad, and Rourkela of India. Indirect ELISA was performed to measure human IgG antibodies against recombinant PvAMA-1 and PvMSP-119 antigens. The difference in seroprevalence and factors associated with antibody responses at each site was statistically analysed. Results The overall seroprevalence was 40.6% for PvAMA-1 and 62.4% for PvMSP-119. Seroprevalence to PvAMA-1 was higher in Chennai (47%) followed by Nadiad (46.7%) and Rourkela (27.6%). For PvMSP-119, seroprevalence was higher in Chennai (80.3%) as compared to Nadiad (53.3%) and Rourkela (57.9%). Seroprevalence for both the antigens were found to be higher in Chennai where P. vivax is the dominant malaria species. In addition, heterogeneous antibody response was observed for PvAMA-1 and PvMSP-119 antigens at each of the study sites. Two factors, age and malaria positivity were significantly associated with seropositivity for both the antigens PvAMA-1 and PvMSP-119. Conclusion These data suggest that natural acquired antibody response is higher for PvMSP-119 antigen as compared to PvAMA-1 antigen in individuals living in three geographically diverse malaria endemic regions in India. PvMSP-119 appears to be highly immunogenic in Indian population and has great potential as a malaria vaccine candidate. The differences in immune response against vaccine candidate antigens in different endemic settings should be taken into account for development of asexual stage based P. vivax malaria vaccine, which in turn can enhance malaria control efforts.
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Affiliation(s)
- Sonal Kale
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India.,Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, India
| | - Chander P Yadav
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India
| | - Pavitra N Rao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, USA
| | - Sneh Shalini
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India
| | - Alex Eapen
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India
| | - Harish C Srivasatava
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India
| | - Surya K Sharma
- Jigyansha, International Center of Excellence for Malaria Research, Sector 1, Rourkela, Odisha, India
| | - Veena Pande
- Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, India
| | - Jane M Carlton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, USA
| | - Om P Singh
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India.
| | - Prashant K Mallick
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India.
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10
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Younis S, Faber BW, Kocken CHM, Remarque EJ. Identification of adjuvants for clinical trials performed with Plasmodium falciparum AMA1 in rabbits. BMC Immunol 2019; 20:25. [PMID: 31362695 PMCID: PMC6664700 DOI: 10.1186/s12865-019-0307-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 07/18/2019] [Indexed: 11/20/2022] Open
Abstract
Background In this study, seven adjuvants were compared for use with Plasmodium falciparum DiCo-Apical Membrane Antigen 1 (Pf-DiCo-AMA1), with the aim to identify an ideal adjuvant which yields high antibody titres and potentially broadens the responses in clinical trials. The following adjuvant formulations were evaluated: SE, SE-GLA, Liposomes, Liposomes-GLA, CoVaccine HT™, ImSaVac-P and ImSaVac-P o/w. The study was performed in rabbits, which were immunized with FVO-AMA1 in combination with one of the seven adjuvants. Antibody levels (humoral responses) and functional activity of the antibodies induced against malaria vaccine candidate AMA1 were evaluated. Thus, in this study the ideal adjuvant is expected to induce high functional antibody levels, a long-lived response, and a broad cross-strain activity. Results AMA1 formulated in all adjuvants was immunogenic. However, the magnitude of the immune responses differed between the seven adjuvants. The highest IgG levels were observed for the CoVaccine HT™ group, this was statistically significant for all four AMA1 variants versus all other adjuvant groups. No differences were observed in the breadth of the humoral response, i.e., increased recognition of AMA1 variants. Also, Growth Inhibition Activity (GIA) for both Plasmodium falciparum strains (FCR3 – homologous to FVO AMA1 protein and NF54 – heterologous to FVO AMA1 protein) were significantly higher in the CoVaccine HT™ group as compared to the other adjuvant groups. Conclusions In brief, all seven vaccine – adjuvant formulations were immunogenic. The magnitude of the immune responses differed between the seven adjuvants. No statistically significant differences were observed in the breadth of the humoral response, nor in longevity of the response. Nevertheless, AMA1 formulated in CoVaccine HT™ appeared as the best adjuvant for use in clinical trials. Electronic supplementary material The online version of this article (10.1186/s12865-019-0307-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sumera Younis
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Bart W Faber
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Clemens H M Kocken
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands
| | - Edmond J Remarque
- Biomedical Primate Research Centre, Department of Parasitology, Rijswijk, The Netherlands.
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11
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Siau A, Huang X, Loh HP, Zhang N, Meng W, Sze SK, Renia L, Preiser P. Immunomic Identification of Malaria Antigens Associated With Protection in Mice. Mol Cell Proteomics 2019; 18:837-853. [PMID: 30718293 DOI: 10.1074/mcp.ra118.000997] [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: 07/30/2018] [Revised: 01/22/2019] [Indexed: 11/06/2022] Open
Abstract
Efforts to develop vaccines against malaria represent a major research target. The observations that 1) sterile protection can be obtained when the host is exposed to live parasites and 2) the immunity against blood stage parasite is principally mediated by protective antibodies suggest that a protective vaccine is feasible. However, only a small number of proteins have been investigated so far and most of the Plasmodium proteome has yet to be explored. To date, only few immunodominant antigens have emerged for testing in clinical trials but no formulation has led to substantial protection in humans. The nature of parasite molecules associated with protection remains elusive. Here, immunomic screening of mice immune sera with different protection efficiencies against the whole parasite proteome allowed us to identify a large repertoire of antigens validated by screening a library expressing antigens. The calculation of weighted scores reflecting the likelihood of protection of each antigen using five predictive criteria derived from immunomic and proteomic data sets, highlighted a priority list of protective antigens. Altogether, the approach sheds light on conserved antigens across Plasmodium that are amenable to targeting by the host immune system upon merozoite invasion and blood stage development. Most of these antigens have preliminary protection data but have not been widely considered as candidate for vaccine trials, opening new perspectives that overcome the limited choice of immunodominant, poorly protective vaccines currently being the focus of malaria vaccine researches.
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Affiliation(s)
- Anthony Siau
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;.
| | - Ximei Huang
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;; From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Han Ping Loh
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;; From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Neng Zhang
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Wei Meng
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Siu Kwan Sze
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore
| | - Laurent Renia
- §Singapore Immunology Network (SIgN), A*STAR, Biopolis, Singapore
| | - Peter Preiser
- From the ‡Nanyang Technological University, School of Biological Sciences, Singapore;.
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12
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Armistead JS, Jennison C, O'Neill MT, Lopaticki S, Liehl P, Hanson KK, Annoura T, Rajasekaran P, Erickson SM, Tonkin CJ, Khan SM, Mota MM, Boddey JA. Plasmodium falciparum
subtilisin-like ookinete protein SOPT plays an important and conserved role during ookinete infection of the Anopheles stephensi
midgut. Mol Microbiol 2018; 109:458-473. [DOI: 10.1111/mmi.13993] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2018] [Indexed: 11/27/2022]
Affiliation(s)
- Jennifer S. Armistead
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
- Department of Medical Biology; The University of Melbourne; Parkville 3052 Australia
| | - Charlie Jennison
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
- Department of Medical Biology; The University of Melbourne; Parkville 3052 Australia
| | - Matthew T. O'Neill
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
| | - Sash Lopaticki
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
| | - Peter Liehl
- Instituto de Medicina Molecular, Faculdade de Medicina; Universidade de Lisboa; 1649-028 Lisbon Portugal
| | - Kirsten K. Hanson
- Instituto de Medicina Molecular, Faculdade de Medicina; Universidade de Lisboa; 1649-028 Lisbon Portugal
| | - Takeshi Annoura
- Leiden Malaria Research Group, Parasitology; Leiden University Medical Centre; 2333ZA Leiden the Netherlands
| | - Pravin Rajasekaran
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
- Department of Medical Biology; The University of Melbourne; Parkville 3052 Australia
| | - Sara M. Erickson
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
- Department of Medical Biology; The University of Melbourne; Parkville 3052 Australia
| | - Christopher J. Tonkin
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
- Department of Medical Biology; The University of Melbourne; Parkville 3052 Australia
| | - Shahid M. Khan
- Leiden Malaria Research Group, Parasitology; Leiden University Medical Centre; 2333ZA Leiden the Netherlands
| | - Maria M. Mota
- Instituto de Medicina Molecular, Faculdade de Medicina; Universidade de Lisboa; 1649-028 Lisbon Portugal
| | - Justin A. Boddey
- The Walter and Eliza Hall Institute of Medical Research; Parkville 3052 Australia
- Department of Medical Biology; The University of Melbourne; Parkville 3052 Australia
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13
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Quintana MDP, Ch’ng JH, Zandian A, Imam M, Hultenby K, Theisen M, Nilsson P, Qundos U, Moll K, Chan S, Wahlgren M. SURGE complex of Plasmodium falciparum in the rhoptry-neck (SURFIN4.2-RON4-GLURP) contributes to merozoite invasion. PLoS One 2018; 13:e0201669. [PMID: 30092030 PMCID: PMC6084945 DOI: 10.1371/journal.pone.0201669] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 07/19/2018] [Indexed: 12/25/2022] Open
Abstract
Plasmodium falciparum invasion into red blood cells (RBCs) is a complex process engaging proteins on the merozoite surface and those contained and sequentially released from the apical organelles (micronemes and rhoptries). Fundamental to invasion is the formation of a moving junction (MJ), a region of close apposition of the merozoite and the RBC plasma membranes, through which the merozoite draws itself before settling into a newly formed parasitophorous vacuole (PV). SURFIN4.2 was identified at the surface of the parasitized RBCs (pRBCs) but was also found apically associated with the merozoite. Using antibodies against the N-terminus of the protein we show the presence of SURFIN4.2 in the neck of the rhoptries, its secretion into the PV and shedding into the culture supernatant upon schizont rupture. Using immunoprecipitation followed by mass spectrometry we describe here a novel protein complex we have named SURGE where SURFIN4.2 forms interacts with the rhoptry neck protein 4 (RON4) and the Glutamate Rich Protein (GLURP). The N-terminal cysteine-rich-domain (CRD) of SURFIN4.2 mediates binding to the RBC membrane and its interaction with RON4 suggests its involvement in the contact between the merozoite apex and the RBC at the MJ. Supporting this suggestion, we also found that polyclonal antibodies to the extracellular domain (including the CRD) of SURFIN4.2 partially inhibit merozoite invasion. We propose that the formation of the SURGE complex participates in the establishment of parasite infection within the PV and the RBCs.
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Affiliation(s)
- Maria del Pilar Quintana
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Jun-Hong Ch’ng
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
- Department of Microbiology and Immunology, National University of Singapore, Singapore, Singapore
| | - Arash Zandian
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, KTH-Royal Institutet of Technology, Stockholm, Sweden
| | - Maryam Imam
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Hultenby
- Division of Clinical Research Centre, Department of Laboratory Medicine, Karolinska Institutet, Huddinge, Sweden
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Peter Nilsson
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, KTH-Royal Institutet of Technology, Stockholm, Sweden
| | - Ulrika Qundos
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, KTH-Royal Institutet of Technology, Stockholm, Sweden
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Sherwin Chan
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum, Karolinska Institutet, Stockholm, Sweden
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14
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Kusi KA, Faber BW, Koopman G, Remarque EJ. EDiP: the Epitope Dilution Phenomenon. Lessons learnt from a malaria vaccine antigen and its applicability to polymorphic antigens. Expert Rev Vaccines 2017; 17:13-21. [PMID: 29224404 DOI: 10.1080/14760584.2018.1411198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
INTRODUCTION Polymorphism in vaccine antigens poses major challenges to vaccinologists. The Plasmodium falciparum Apical Membrane Antigen 1 (AMA1) poses such a challenge. We found that immunization with a mixture of three variants yielded functional antibody levels to all variants comparable to levels induced by monovalent immunization. The mechanism behind the observed broadening was shown to be an increase in the fraction of cross-reactive antibodies, most likely because strain-specific epitopes are present at lower frequency relative to conserved epitopes. Areas covered: We hereby introduce the Epitope Dilution Phenomenon (EDiP) as a practical strategy for the induction of broad, cross-variant antibody responses against polymorphic antigens and discuss the utility and applicability of this phenomenon for the development of vaccines against polymorphic antigens of pathogens like Influenza, HIV, Dengue and Plasmodium. Expert commentary: EDiP can be used to broaden antibody responses by immunizing with a mixture of at least 3 antigenic variants, where the variants included can differ, yet yield broadened responses.
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Affiliation(s)
- Kwadwo Asamoah Kusi
- a Immunology Department , Noguchi Memorial Institute for Medical Research, College of Health Sciences University of Ghana , Accra , Ghana
| | - Bart W Faber
- b Department of Parasitology , Biomedical Primate Research Centre , Rijswijk , The Netherlands
| | - Gerrit Koopman
- c Department of Virology , Biomedical Primate Research Centre , Rijswijk , The Netherlands
| | - Edmond Joseph Remarque
- c Department of Virology , Biomedical Primate Research Centre , Rijswijk , The Netherlands
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15
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Safety and immunogenicity of a recombinant Plasmodium falciparum AMA1-DiCo malaria vaccine adjuvanted with GLA-SE or Alhydrogel® in European and African adults: A phase 1a/1b, randomized, double-blind multi-centre trial. Vaccine 2017; 35:6218-6227. [DOI: 10.1016/j.vaccine.2017.09.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 07/28/2017] [Accepted: 09/07/2017] [Indexed: 11/20/2022]
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16
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Arévalo-Pinzón G, Bermúdez M, Hernández D, Curtidor H, Patarroyo MA. Plasmodium vivax ligand-receptor interaction: PvAMA-1 domain I contains the minimal regions for specific interaction with CD71+ reticulocytes. Sci Rep 2017; 7:9616. [PMID: 28855657 PMCID: PMC5577344 DOI: 10.1038/s41598-017-10025-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 08/02/2017] [Indexed: 12/18/2022] Open
Abstract
The malarial parasite’s invasion is complex, active and coordinated, involving many low and high affinity interactions with receptors on target cell membrane. Proteomics analysis has described around 40 proteins in P. vivax which could be involved in reticulocyte invasion; few have been studied with the aim of elucidating how many of them establish specific interactions with their respective host cells. Given the importance of knowing which of the parasite’s protein regions are functionally important for invasion, minimum regions mediating specific interaction between Plasmodium vivax apical membrane antigen 1 (PvAMA-1) and its host cell were here elucidated. The region covering PvAMA-1 domains I and II (PvAMA-DI-II) specifically bound to the CD71+ red blood cell subpopulation. A 20 residue-long region (81EVENAKYRIPAGRCPVFGKG100) located in domain I was capable of inhibiting PvAMA-DI-II recombinant protein binding to young reticulocytes (CD71+CD45−) and rosette formation. This conserved peptide specifically interacted with high affinity with reticulocytes (CD71+) through a neuraminidase- and chymotrypsin-treatment sensitive receptor. Such results showed that, despite AMA-1 having universal functions during late Plasmodium invasion stages, PvAMA-1 had reticulocyte-preferring binding regions, suggesting that P. vivax target cell selection is not just restricted to initial interactions but maintained throughout the erythrocyte invasion cycle, having important implications for designing a specific anti-P. vivax vaccine.
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Affiliation(s)
- Gabriela Arévalo-Pinzón
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia.,PhD Program in Biomedical and Biological Sciences, Universidad del Rosario, Carrera 24 #, 63C-69, Bogotá, Colombia
| | - Maritza Bermúdez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia.,MSc Program in Biological Sciences, Pontificia Universidad Javeriana, Carrera 7 # 40-62, Bogotá, Colombia
| | - Diana Hernández
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia
| | - Hernando Curtidor
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 #, 63C-69, Bogotá, Colombia
| | - Manuel Alfonso Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia. .,School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 #, 63C-69, Bogotá, Colombia.
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17
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Host immunity to Plasmodium falciparum and the assessment of emerging artemisinin resistance in a multinational cohort. Proc Natl Acad Sci U S A 2017; 114:3515-3520. [PMID: 28289193 DOI: 10.1073/pnas.1615875114] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Artemisinin-resistant falciparum malaria, defined by a slow-clearance phenotype and the presence of kelch13 mutants, has emerged in the Greater Mekong Subregion. Naturally acquired immunity to malaria clears parasites independent of antimalarial drugs. We hypothesized that between- and within-population variations in host immunity influence parasite clearance after artemisinin treatment and the interpretation of emerging artemisinin resistance. Antibodies specific to 12 Plasmodium falciparum sporozoite and blood-stage antigens were determined in 959 patients (from 11 sites in Southeast Asia) participating in a multinational cohort study assessing parasite clearance half-life (PCt1/2) after artesunate treatment and kelch13 mutations. Linear mixed-effects modeling of pooled individual patient data assessed the association between antibody responses and PCt1/2.P. falciparum antibodies were lowest in areas where the prevalence of kelch13 mutations and slow PCt1/2 were highest [Spearman ρ = -0.90 (95% confidence interval, -0.97, -0.65), and Spearman ρ = -0.94 (95% confidence interval, -0.98, -0.77), respectively]. P. falciparum antibodies were associated with faster PCt1/2 (mean difference in PCt1/2 according to seropositivity, -0.16 to -0.65 h, depending on antigen); antibodies have a greater effect on the clearance of kelch13 mutant compared with wild-type parasites (mean difference in PCt1/2 according to seropositivity, -0.22 to -0.61 h faster in kelch13 mutants compared with wild-type parasites). Naturally acquired immunity accelerates the clearance of artemisinin-resistant parasites in patients with falciparum malaria and may confound the current working definition of artemisinin resistance. Immunity may also play an important role in the emergence and transmission potential of artemisinin-resistant parasites.
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18
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Maskus DJ, Królik M, Bethke S, Spiegel H, Kapelski S, Seidel M, Addai-Mensah O, Reimann A, Klockenbring T, Barth S, Fischer R, Fendel R. Characterization of a novel inhibitory human monoclonal antibody directed against Plasmodium falciparum Apical Membrane Antigen 1. Sci Rep 2016; 6:39462. [PMID: 28000709 PMCID: PMC5175200 DOI: 10.1038/srep39462] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/22/2016] [Indexed: 01/07/2023] Open
Abstract
Malaria remains a major challenge to global health causing extensive morbidity and mortality. Yet, there is no efficient vaccine and the immune response remains incompletely understood. Apical Membrane Antigen 1 (AMA1), a leading vaccine candidate, plays a key role during merozoite invasion into erythrocytes by interacting with Rhoptry Neck Protein 2 (RON2). We generated a human anti-AMA1-antibody (humAbAMA1) by EBV-transformation of sorted B-lymphocytes from a Ghanaian donor and subsequent rescue of antibody variable regions. The antibody was expressed in Nicotiana benthamiana and in HEK239-6E, characterized for binding specificity and epitope, and analyzed for its inhibitory effect on Plasmodium falciparum. The generated humAbAMA1 shows an affinity of 106-135 pM. It inhibits the parasite strain 3D7A growth in vitro with an expression system-independent IC50-value of 35 μg/ml (95% confidence interval: 33 μg/ml-37 μg/ml), which is three to eight times lower than the IC50-values of inhibitory antibodies 4G2 and 1F9. The epitope was mapped to the close proximity of the RON2-peptide binding groove. Competition for binding between the RON2-peptide and humAbAMA1 was confirmed by surface plasmon resonance spectroscopy measurements. The particularly advantageous inhibitory activity of this fully human antibody might provide a basis for future therapeutic applications.
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Affiliation(s)
- Dominika J. Maskus
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Michał Królik
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Susanne Bethke
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Stephanie Kapelski
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Melanie Seidel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Otchere Addai-Mensah
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Torsten Klockenbring
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Stefan Barth
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
- Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany
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Contrasting Patterns of Serologic and Functional Antibody Dynamics to Plasmodium falciparum Antigens in a Kenyan Birth Cohort. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 23:104-16. [PMID: 26656119 PMCID: PMC4744923 DOI: 10.1128/cvi.00452-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/20/2015] [Indexed: 11/20/2022]
Abstract
IgG antibodies to Plasmodium falciparum are transferred from the maternal to fetal circulation during pregnancy, wane after birth, and are subsequently acquired in response to natural infection. We examined the dynamics of malaria antibody responses of 84 Kenyan infants from birth to 36 months of age by (i) serology, (ii) variant surface antigen (VSA) assay, (iii) growth inhibitory activity (GIA), and (iv) invasion inhibition assays (IIA) specific for merozoite surface protein 1 (MSP1) and sialic acid-dependent invasion pathway. Maternal antibodies in each of these four categories were detected in cord blood and decreased to their lowest level by approximately 6 months of age. Serologic antibodies to 3 preerythrocytic and 10 blood-stage antigens subsequently increased, reaching peak prevalence by 36 months. In contrast, antibodies measured by VSA, GIA, and IIA remained low even up to 36 months. Infants sensitized to P. falciparum in utero, defined by cord blood lymphocyte recall responses to malaria antigens, acquired antimalarial antibodies at the same rate as those who were not sensitized in utero, indicating that fetal exposure to malaria antigens did not affect subsequent infant antimalarial responses. Infants with detectable serologic antibodies at 12 months of age had an increased risk of P. falciparum infection during the subsequent 24 months. We conclude that serologic measures of antimalarial antibodies in children 36 months of age or younger represent biomarkers of malaria exposure rather than protection and that functional antibodies develop after 36 months of age in this population.
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Chia WN, Goh YS, Rénia L. Novel approaches to identify protective malaria vaccine candidates. Front Microbiol 2014; 5:586. [PMID: 25452745 PMCID: PMC4233905 DOI: 10.3389/fmicb.2014.00586] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/17/2014] [Indexed: 12/17/2022] Open
Abstract
Efforts to develop vaccines against malaria have been the focus of substantial research activities for decades. Several categories of candidate vaccines are currently being developed for protection against malaria, based on antigens corresponding to the pre-erythrocytic, blood stage, or sexual stages of the parasite. Long lasting sterile protection from Plasmodium falciparum sporozoite challenge has been observed in human following vaccination with whole parasite formulations, clearly demonstrating that a protective immune response targeting predominantly the pre-erythrocytic stages can develop against malaria. However, most of vaccine candidates currently being investigated, which are mostly subunits vaccines, have not been able to induce substantial (>50%) protection thus far. This is due to the fact that the antigens responsible for protection against the different parasite stages are still yet to be known and relevant correlates of protection have remained elusive. For a vaccine to be developed in a timely manner, novel approaches are required. In this article, we review the novel approaches that have been developed to identify the antigens for the development of an effective malaria vaccine.
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Affiliation(s)
- Wan Ni Chia
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore ; Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore Singapore, Singapore
| | - Yun Shan Goh
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore
| | - Laurent Rénia
- Singapore Immunology Network, Agency for Science, Technology and Research Singapore, Singapore ; Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore Singapore, Singapore
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21
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Riley EM. Searching for Achilles' heel: can rational design of malaria vaccines overcome antigenic diversity? Pathog Glob Health 2014; 108:63-4. [PMID: 24649865 DOI: 10.1179/2047772414z.000000000188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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22
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Serine Proteases of Malaria Parasite Plasmodium falciparum: Potential as Antimalarial Drug Targets. Interdiscip Perspect Infect Dis 2014; 2014:453186. [PMID: 24799897 PMCID: PMC3988940 DOI: 10.1155/2014/453186] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/02/2014] [Accepted: 01/07/2014] [Indexed: 01/08/2023] Open
Abstract
Malaria is a major global parasitic disease and a cause of enormous mortality and morbidity. Widespread drug resistance against currently available antimalarials warrants the identification of novel drug targets and development of new drugs. Malarial proteases are a group of molecules that serve as potential drug targets because of their essentiality for parasite life cycle stages and feasibility of designing specific inhibitors against them. Proteases belonging to various mechanistic classes are found in P. falciparum, of which serine proteases are of particular interest due to their involvement in parasite-specific processes of egress and invasion. In P. falciparum, a number of serine proteases belonging to chymotrypsin, subtilisin, and rhomboid clans are found. This review focuses on the potential of P. falciparum serine proteases as antimalarial drug targets.
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Dutta S, Dlugosz LS, Drew DR, Ge X, Ababacar D, Rovira YI, Moch JK, Shi M, Long CA, Foley M, Beeson JG, Anders RF, Miura K, Haynes JD, Batchelor AH. Overcoming antigenic diversity by enhancing the immunogenicity of conserved epitopes on the malaria vaccine candidate apical membrane antigen-1. PLoS Pathog 2013; 9:e1003840. [PMID: 24385910 PMCID: PMC3873463 DOI: 10.1371/journal.ppat.1003840] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 11/04/2013] [Indexed: 12/16/2022] Open
Abstract
Malaria vaccine candidate Apical Membrane Antigen-1 (AMA1) induces protection, but only against parasite strains that are closely related to the vaccine. Overcoming the AMA1 diversity problem will require an understanding of the structural basis of cross-strain invasion inhibition. A vaccine containing four diverse allelic proteins 3D7, FVO, HB3 and W2mef (AMA1 Quadvax or QV) elicited polyclonal rabbit antibodies that similarly inhibited the invasion of four vaccine and 22 non-vaccine strains of P. falciparum. Comparing polyclonal anti-QV with antibodies against a strain-specific, monovalent, 3D7 AMA1 vaccine revealed that QV induced higher levels of broadly inhibitory antibodies which were associated with increased conserved face and domain-3 responses and reduced domain-2 response. Inhibitory monoclonal antibodies (mAb) raised against the QV reacted with a novel cross-reactive epitope at the rim of the hydrophobic trough on domain-1; this epitope mapped to the conserved face of AMA1 and it encompassed the 1e-loop. MAbs binding to the 1e-loop region (1B10, 4E8 and 4E11) were ∼10-fold more potent than previously characterized AMA1-inhibitory mAbs and a mode of action of these 1e-loop mAbs was the inhibition of AMA1 binding to its ligand RON2. Unlike the epitope of a previously characterized 3D7-specific mAb, 1F9, the 1e-loop inhibitory epitope was partially conserved across strains. Another novel mAb, 1E10, which bound to domain-3, was broadly inhibitory and it blocked the proteolytic processing of AMA1. By itself mAb 1E10 was weakly inhibitory but it synergized with a previously characterized, strain-transcending mAb, 4G2, which binds close to the hydrophobic trough on the conserved face and inhibits RON2 binding to AMA1. Novel inhibition susceptible regions and epitopes, identified here, can form the basis for improving the antigenic breadth and inhibitory response of AMA1 vaccines. Vaccination with a few diverse antigenic proteins could provide universal coverage by redirecting the immune response towards conserved epitopes. Numerous reports of vaccine failure are attributed to a mismatch between the genotype of the vaccine and the circulating target strains. This observation is congruent to the view that polyvalent vaccines protect broadly by inducing a multitude of type-specific antibodies. Polyvalent vaccines that can overcome antigenic diversity by refocusing antibody responses towards conserved functional epitopes are highly desirable. Development of an Apical Membrane Antigen-1 (AMA1) malaria vaccine has been impeded by extreme antigenic diversity in the field. We present here a solution to the AMA1 diversity problem. Antibodies against a mixture of only four naturally occurring AMA1 allelic proteins “Quadvax” inhibited invasion of red blood cells by a diverse panel of malaria parasites that represented the global diversity of AMA1 in the field. Competition experiments suggested that in addition to improving the diversity of strain-specific antibodies, the mechanism of broadened inhibition involved an increase in responses against conserved inhibitory epitopes. Monoclonal antibodies against the Quadvax inhibited invasion either by blocking the binding of AMA1 to its receptor RON2 or by blocking a crucial proteolytic processing event. Some mixtures of these antibodies were much more effective than expected and were shown to act synergistically. Together these two classes of functional invasion inhibitory epitopes can be targeted to engineer a more potent AMA1 vaccine.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/immunology
- Antigenic Variation/genetics
- Antigenic Variation/immunology
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Cells, Cultured
- Conserved Sequence/immunology
- Epitope Mapping
- Epitopes/genetics
- Epitopes/immunology
- Immunity, Humoral
- Malaria Vaccines/chemistry
- Malaria Vaccines/immunology
- Membrane Proteins/chemistry
- Membrane Proteins/genetics
- Membrane Proteins/immunology
- Mice
- Mice, Nude
- Models, Molecular
- Plasmodium berghei/genetics
- Plasmodium berghei/immunology
- Plasmodium falciparum/immunology
- Protein Structure, Tertiary
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Rabbits
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/immunology
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Affiliation(s)
- Sheetij Dutta
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
- * E-mail:
| | - Lisa S. Dlugosz
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | | | - Xiopeng Ge
- Department of Biochemistry, La Trobe University, Victoria, Australia
| | - Diouf Ababacar
- Laboratory of Malaria and Vector Research, National Institutes of Health, Rockville, Maryland, United States of America
| | - Yazmin I. Rovira
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - J. Kathleen Moch
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Meng Shi
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, National Institutes of Health, Rockville, Maryland, United States of America
| | - Michael Foley
- Department of Biochemistry, La Trobe University, Victoria, Australia
| | | | - Robin F. Anders
- Department of Biochemistry, La Trobe University, Victoria, Australia
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institutes of Health, Rockville, Maryland, United States of America
| | - J. David Haynes
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
| | - Adrian H. Batchelor
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
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24
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Douglas AD, Williams AR, Knuepfer E, Illingworth JJ, Furze JM, Crosnier C, Choudhary P, Bustamante LY, Zakutansky SE, Awuah DK, Alanine DGW, Theron M, Worth A, Shimkets R, Rayner JC, Holder AA, Wright GJ, Draper SJ. Neutralization of Plasmodium falciparum merozoites by antibodies against PfRH5. THE JOURNAL OF IMMUNOLOGY 2013; 192:245-58. [PMID: 24293631 DOI: 10.4049/jimmunol.1302045] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
There is intense interest in induction and characterization of strain-transcending neutralizing Ab against antigenically variable human pathogens. We have recently identified the human malaria parasite Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5) as a target of broadly neutralizing Abs, but there is little information regarding the functional mechanism(s) of Ab-mediated neutralization. In this study, we report that vaccine-induced polyclonal anti-PfRH5 Abs inhibit the tight attachment of merozoites to erythrocytes and are capable of blocking the interaction of PfRH5 with its receptor basigin. Furthermore, by developing anti-PfRH5 mAbs, we provide evidence of the following: 1) the ability to block the PfRH5-basigin interaction in vitro is predictive of functional activity, but absence of blockade does not predict absence of functional activity; 2) neutralizing mAbs bind spatially related epitopes on the folded protein, involving at least two defined regions of the PfRH5 primary sequence; 3) a brief exposure window of PfRH5 is likely to necessitate rapid binding of Ab to neutralize parasites; and 4) intact bivalent IgG contributes to but is not necessary for parasite neutralization. These data provide important insight into the mechanisms of broadly neutralizing anti-malaria Abs and further encourage anti-PfRH5-based malaria prevention efforts.
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25
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Walker DM, Oghumu S, Gupta G, McGwire BS, Drew ME, Satoskar AR. Mechanisms of cellular invasion by intracellular parasites. Cell Mol Life Sci 2013; 71:1245-63. [PMID: 24221133 DOI: 10.1007/s00018-013-1491-1] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 12/22/2022]
Abstract
Numerous disease-causing parasites must invade host cells in order to prosper. Collectively, such pathogens are responsible for a staggering amount of human sickness and death throughout the world. Leishmaniasis, Chagas disease, toxoplasmosis, and malaria are neglected diseases and therefore are linked to socio-economical and geographical factors, affecting well-over half the world's population. Such obligate intracellular parasites have co-evolved with humans to establish a complexity of specific molecular parasite-host cell interactions, forming the basis of the parasite's cellular tropism. They make use of such interactions to invade host cells as a means to migrate through various tissues, to evade the host immune system, and to undergo intracellular replication. These cellular migration and invasion events are absolutely essential for the completion of the lifecycles of these parasites and lead to their for disease pathogenesis. This review is an overview of the molecular mechanisms of protozoan parasite invasion of host cells and discussion of therapeutic strategies, which could be developed by targeting these invasion pathways. Specifically, we focus on four species of protozoan parasites Leishmania, Trypanosoma cruzi, Plasmodium, and Toxoplasma, which are responsible for significant morbidity and mortality.
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Affiliation(s)
- Dawn M Walker
- Department of Microbial Infection and Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, 43210, USA
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26
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Acquired antibodies to merozoite antigens in children from Uganda with uncomplicated or severe Plasmodium falciparum malaria. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:1170-80. [PMID: 23740926 DOI: 10.1128/cvi.00156-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Malaria can present itself as an uncomplicated or severe disease. We have here studied the quantity and quality of antibody responses against merozoite antigens, as well as multiplicity of infection (MOI), in children from Uganda. We found higher levels of IgG antibodies toward erythrocyte-binding antigen EBA181, MSP2 of Plasmodium falciparum 3D7 and FC27 (MSP2-3D7/FC27), and apical membrane antigen 1 (AMA1) in patients with uncomplicated malaria by enzyme-linked immunosorbent assay (ELISA) but no differences against EBA140, EBA175, MSP1, and reticulocyte-binding protein homologues Rh2 and Rh4 or for IgM against MSP2-3D7/FC27.Patients with uncomplicated malaria were also shown to have higher antibody affinities for AMA1 by surface plasmon resonance (SPR). Decreased invasion of two clinical P. falciparum isolates in the presence of patient plasma correlated with lower initial parasitemia in the patients, in contrast to comparisons of parasitemia to ELISA values or antibody affinities, which did not show any correlations. Analysis of the heterogeneity of the infections revealed a higher MOI in patients with uncomplicated disease, with the P. falciparum K1 MSP1 (MSP1-K1) and MSP2-3D7 being the most discriminative allelic markers. Higher MOIs also correlated positively with higher antibody levels in several of the ELISAs. In conclusion, certain antibody responses and MOIs were associated with differences between uncomplicated and severe malaria. When different assays were combined, some antibodies, like those against AMA1, seemed particularly discriminative. However, only decreased invasion correlated with initial parasitemia in the patient, signaling the importance of functional assays in understanding development of immunity against malaria and in evaluating vaccine candidates.
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27
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Plasmodium falciparum 19-kilodalton merozoite surface protein 1 (MSP1)-specific antibodies that interfere with parasite growth in vitro can inhibit MSP1 processing, merozoite invasion, and intracellular parasite development. Infect Immun 2011; 80:1280-7. [PMID: 22202121 DOI: 10.1128/iai.05887-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Merozoite surface protein 1 (MSP1) is a target for malaria vaccine development. Antibodies to the 19-kDa carboxy-terminal region referred to as MSP1(19) inhibit erythrocyte invasion and parasite growth, with some MSP1-specific antibodies shown to inhibit the proteolytic processing of MSP1 that occurs at invasion. We investigated a series of antibodies purified from rabbits immunized with MSP1(19) and AMA1 recombinant proteins for their ability to inhibit parasite growth, initially looking at MSP1 processing. Although significant inhibition of processing was mediated by several of the antibody samples, there was no clear relationship with overall growth inhibition by the same antibodies. However, no antibody samples inhibited processing but not invasion, suggesting that inhibition of MSP1 processing contributes to but is not the only mechanism of antibody-mediated inhibition of invasion and growth. Examining other mechanisms by which MSP1-specific antibodies inhibit parasite growth, we show that MSP1(19)-specific antibodies are taken up into invaded erythrocytes, where they persist for significant periods and result in delayed intracellular parasite development. This delay may result from antibody interference with coalescence of MSP1(19)-containing vesicles with the food vacuole. Antibodies raised against a modified recombinant MSP1(19) sequence were more efficient at delaying intracellular growth than those to the wild-type protein. We propose that antibodies specific for MSP1(19) can mediate inhibition of parasite growth by at least three mechanisms: inhibition of MSP1 processing, direct inhibition of invasion, and inhibition of parasite development following invasion. The balance between mechanisms may be modulated by modifying the immunogen used to induce the antibodies.
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28
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Olivieri A, Collins CR, Hackett F, Withers-Martinez C, Marshall J, Flynn HR, Skehel JM, Blackman MJ. Juxtamembrane shedding of Plasmodium falciparum AMA1 is sequence independent and essential, and helps evade invasion-inhibitory antibodies. PLoS Pathog 2011; 7:e1002448. [PMID: 22194692 PMCID: PMC3240622 DOI: 10.1371/journal.ppat.1002448] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 11/04/2011] [Indexed: 12/16/2022] Open
Abstract
The malarial life cycle involves repeated rounds of intraerythrocytic replication interspersed by host cell rupture which releases merozoites that rapidly invade fresh erythrocytes. Apical membrane antigen-1 (AMA1) is a merozoite protein that plays a critical role in invasion. Antibodies against AMA1 prevent invasion and can protect against malaria in vivo, so AMA1 is of interest as a malaria vaccine candidate. AMA1 is efficiently shed from the invading parasite surface, predominantly through juxtamembrane cleavage by a membrane-bound protease called SUB2, but also by limited intramembrane cleavage. We have investigated the structural requirements for shedding of Plasmodium falciparum AMA1 (PfAMA1), and the consequences of its inhibition. Mutagenesis of the intramembrane cleavage site by targeted homologous recombination abolished intramembrane cleavage with no effect on parasite viability in vitro. Examination of PfSUB2-mediated shedding of episomally-expressed PfAMA1 revealed that the position of cleavage is determined primarily by its distance from the parasite membrane. Certain mutations at the PfSUB2 cleavage site block shedding, and parasites expressing these non-cleavable forms of PfAMA1 on a background of expression of the wild type gene invade and replicate normally in vitro. The non-cleavable PfAMA1 is also functional in invasion. However – in contrast to the intramembrane cleavage site - mutations that block PfSUB2-mediated shedding could not be stably introduced into the genomic pfama1 locus, indicating that some shedding of PfAMA1 by PfSUB2 is essential. Remarkably, parasites expressing shedding-resistant forms of PfAMA1 exhibit enhanced sensitivity to antibody-mediated inhibition of invasion. Drugs that inhibit PfSUB2 activity should block parasite replication and may also enhance the efficacy of vaccines based on AMA1 and other merozoite surface proteins. The malaria parasite invades red blood cells. During invasion several parasite proteins, including a vaccine candidate called PfAMA1, are clipped from the parasite surface. Most of this clipping is performed by an enzyme called PfSUB2, but some also occurs through intramembrane cleavage. The function of this shedding is unknown. We have examined the requirements for shedding of PfAMA1, and the effects of mutations that block shedding. Mutations that block intramembrane cleavage have no effect on the parasite. We then show that PfSUB2 does not recognise a specific amino acid sequence in PfAMA1, but rather cleaves it at a position determined primarily by its distance from the parasite membrane. Certain mutations at the PfSUB2 cleavage site prevent shedding, and parasites expressing non-cleavable PfAMA1 along with unmodified PfAMA1 grow normally. However, these mutations cannot be introduced into the parasite's genome, showing that some shedding by PfSUB2 is essential for parasite survival. Parasites expressing shedding-resistant mutants of PfAMA1 show enhanced sensitivity to invasion-inhibitory antibodies, suggesting that shedding of surface proteins during invasion helps the parasite to evade potentially protective antibodies. Drugs that inhibit PfSUB2 may prevent disease and enhance the efficacy of vaccines based on PfAMA1.
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Affiliation(s)
- Anna Olivieri
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Christine R. Collins
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Fiona Hackett
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | | | - Joshua Marshall
- Division of Parasitology, MRC National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Helen R. Flynn
- Protein Analysis and Proteomics Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms, Hertfordshire, United Kingdom
| | - J. Mark Skehel
- Protein Analysis and Proteomics Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms, Hertfordshire, United Kingdom
| | - Michael J. Blackman
- Protein Analysis and Proteomics Laboratory, Clare Hall Laboratories, Cancer Research UK London Research Institute, South Mimms, Hertfordshire, United Kingdom
- * E-mail:
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29
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Miura K, Perera S, Brockley S, Zhou H, Aebig JA, Moretz SE, Miller LH, Doumbo OK, Sagara I, Dicko A, Ellis RD, Long CA. Non-apical membrane antigen 1 (AMA1) IgGs from Malian children interfere with functional activity of AMA1 IgGs as judged by growth inhibition assay. PLoS One 2011; 6:e20947. [PMID: 21695140 PMCID: PMC3113848 DOI: 10.1371/journal.pone.0020947] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 05/13/2011] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Apical membrane antigen 1 (AMA1) is one of the best-studied blood-stage malaria vaccine candidates. When an AMA1 vaccine was tested in a malaria naïve population, it induced functionally active antibodies judged by Growth Inhibition Assay (GIA). However, the same vaccine failed to induce higher growth-inhibitory activity in adults living in a malaria endemic area. Vaccination did induce functionally active antibodies in malaria-exposed children with less than 20% inhibition in GIA at baseline, but not in children with more than that level of baseline inhibition. METHODS Total IgGs were purified from plasmas collected from the pediatric trial before and after immunization and pools of total IgGs were made. Another set of total IgGs was purified from U.S. adults immunized with AMA1 (US-total IgG). From these total IgGs, AMA1-specific and non-AMA1 IgGs were affinity purified and the functional activity of these IgGs was evaluated by GIA. Competition ELISA was performed with the U.S.-total IgG and non-AMA1 IgGs from malaria-exposed children. RESULTS AMA1-specific IgGs from malaria-exposed children and U.S. vaccinees showed similar growth-inhibitory activity at the same concentrations. When mixed with U.S.-total IgG, non-AMA1 IgGs from children showed an interference effect in GIA. Interestingly, the interference effect was higher with non-AMA1 IgGs from higher titer pools. The non-AMA1 IgGs did not compete with anti-AMA1 antibody in U.S.-total IgG in the competition ELISA. CONCLUSION Children living in a malaria endemic area have a fraction of IgGs that interferes with the biological activity of anti-AMA1 antibody as judged by GIA. While the mechanism of interference is not resolved in this study, these results suggest it is not caused by direct competition between non-AMA1 IgG and AMA1 protein. This study indicates that anti-malaria IgGs induced by natural exposure may interfere with the biological effect of antibody induced by an AMA1-based vaccine in the target population.
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Affiliation(s)
- Kazutoyo Miura
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail: (KM); (CAL)
| | - Suwani Perera
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Sarah Brockley
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Hong Zhou
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Joan A. Aebig
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Samuel E. Moretz
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Louis H. Miller
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Ogobara K. Doumbo
- Malaria Research and Training Center, Faculty of Medicine Pharmacy and Dentistry, University of Bamako, Bamako, Mali
| | - Issaka Sagara
- Malaria Research and Training Center, Faculty of Medicine Pharmacy and Dentistry, University of Bamako, Bamako, Mali
| | - Alassane Dicko
- Malaria Research and Training Center, Faculty of Medicine Pharmacy and Dentistry, University of Bamako, Bamako, Mali
| | - Ruth D. Ellis
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail: (KM); (CAL)
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Pan D, Hu J, Ma Q, Pan W, Li M. Diversity and prevalence of the C-terminal region of Plasmodium falciparum merozoite surface protein 1 in China. Acta Trop 2010; 116:200-5. [PMID: 20709011 DOI: 10.1016/j.actatropica.2010.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 08/05/2010] [Accepted: 08/05/2010] [Indexed: 10/19/2022]
Abstract
Malaria continues to be a significant health concern for regions of southeastern Asia. Scientists have focused much effort on the development and regional testing of a vaccine against the most virulent of the pathogens that cause the disease, Plasmodium falciparum. The 19kDa COOH-terminal region of the merozoite surface protein 1 (PfMSP1-19) is considered to be a potentially important component of a malaria vaccine and yet, to date, there is little data from China with regard to Pfmsp1-19 diversity. We have collected samples from 300 individuals diagnosed with P. falciparum infections from Yunnan and Hainan provinces--two potential vaccine trial sites in China. We determined the sequence of DNA encoding PfMSP1-19 for each. We identified seven polymorphic positions; varying arrangements of which accounted for 10 distinct Pfmsp1-19 haplotypes. Four haplotypes, however, represented more than 93% of the total. Differences in the prevalence of haplotypes between Yunnan and Hainan provinces were observed, even though the distribution of haplotypes in Yunnan province seemed to be very similar to those reported for Vietnam and Thailand. These results provide necessary information for the design of a major human vaccine trial as well as a basis for subsequent interpretations of the results. On broader scale, the data should complement the existing database on the prevalence and distribution of Pfmsp1-19 haplotypes and therefore have potential use in the design of PfMSP1-19-based polyvalent vaccines for use in Southeastern Asian countries.
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Li C, Wang R, Wu Y, Zhang D, He Z, Pan W. Epitope mapping of PfCP-2.9, an asexual blood-stage vaccine candidate of Plasmodium falciparum. Malar J 2010; 9:94. [PMID: 20384992 PMCID: PMC2883548 DOI: 10.1186/1475-2875-9-94] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Accepted: 04/12/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Apical membrane antigen 1 (AMA-1) and merozoite surface protein 1 (MSP1) of Plasmodium falciparum are two leading blood-stage malaria vaccine candidates. A P. falciparum chimeric protein 2.9 (PfCP-2.9) has been constructed as a vaccine candidate, by fusing AMA-1 domain III (AMA-1 (III)) with a C-terminal 19 kDa fragment of MSP1 (MSP1-19) via a 28-mer peptide hinge. PfCP-2.9 was highly immunogenic in animal studies, and antibodies elicited by the PfCP-2.9 highly inhibited parasite growth in vitro. This study focused on locating the distribution of epitopes on PfCP-2.9. METHODS A panel of anti-PfCP-2.9 monoclonal antibodies (mAbs) were produced and their properties were examined by Western blot as well as in vitro growth inhibition assay (GIA). In addition, a series of PfCP-2.9 mutants containing single amino acid substitution were produced in Pichia pastoris. Interaction of the mAbs with the PfCP-2.9 mutants was measured by both Western blot and enzyme-linked immunosorbent assay (ELISA). RESULTS Twelve mAbs recognizing PfCP-2.9 chimeric protein were produced. Of them, eight mAbs recognized conformational epitopes and six mAbs showed various levels of inhibitory activities on parasite growth in vitro. In addition, seventeen PfCP-2.9 mutants with single amino acid substitution were produced in Pichia pastoris for interaction with mAbs. Reduced binding of an inhibitory mAb (mAb7G), was observed in three mutants including M62 (Phe491-->Ala), M82 (Glu511-->Gln) and M84 (Arg513-->Lys), suggesting that these amino acid substitutions are critical to the epitope corresponding to mAb7G. The binding of two non-inhibitory mAbs (mAbG11.12 and mAbW9.10) was also reduced in the mutants of either M62 or M82. The substitution of Leu31 to Arg resulted in completely abolishing the binding of mAb1E1 (a blocking antibody) to M176 mutant, suggesting that the Leu residue at this position plays a crucial role in the formation of the epitope. In addition, the Asn15 residue may also play an important role in the global folding of PfCP-2.9, as its substitution by Arg lead to reduced binding of most mAbs and abolishing the binding of mAb6G and mAbP5-W12. CONCLUSIONS This study provided valuable information on epitopes of PfCP-2.9 vaccine candidate through generation of a panel of mAbs and a series of PfCP-2.9 mutants. The information may prove to be useful for designing more effective malaria vaccines against blood-stage parasites.
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Affiliation(s)
- Changling Li
- Department of Pathogenic Biology, Second Military Medical University, 800 Xiang Yin Road, Shanghai 200433, China
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Goodman AL, Draper SJ. Blood-stage malaria vaccines - recent progress and future challenges. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2010; 104:189-211. [PMID: 20507694 DOI: 10.1179/136485910x12647085215534] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Plasmodium falciparum malaria is a major global health problem, responsible for up to 1 million deaths each year. Major efforts have been made to develop an effective vaccine against this disease, to reduce the associated morbidity and mortality. There has already been considerable progress, with the first vaccine against the pre-erythrocytic stages of P. falciparum now en route to licensure. There remains, however, a strong scientific rationale for the development of a highly effective additional vaccine component against the blood stages of the parasite, which could be deployed in conjunction with partially effective control measures against the pre-erythrocytic stages. Here, recent progress in the clinical development of blood-stage vaccines is reviewed, including methods of antigen selection, the limitations of in-vitro assays for selecting vaccines for clinical development, and the results of recently published clinical trials. This review seeks to summarize recent developments in our understanding of immunity to blood-stage parasites, as well as the relevant key advances made in vaccine technologies over the last decade. The future challenges that face this field of vaccine research are also described.
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Affiliation(s)
- A L Goodman
- The Jenner Institute, University of Oxford, Oxford OX3 7DQ, UK.
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Woehlbier U, Epp C, Hackett F, Blackman MJ, Bujard H. Antibodies against multiple merozoite surface antigens of the human malaria parasite Plasmodium falciparum inhibit parasite maturation and red blood cell invasion. Malar J 2010; 9:77. [PMID: 20298576 PMCID: PMC2847572 DOI: 10.1186/1475-2875-9-77] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 03/18/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum merozoites expose at their surface a large protein complex, which is composed of fragments of merozoite surface protein 1 (MSP-1; called MSP-183, MSP-130, MSP-138, and MSP-142) plus associated processing products of MSP-6 and MSP-7. During erythrocyte invasion this complex, as well as an integral membrane protein called apical membrane antigen-1 (AMA-1), is shed from the parasite surface following specific proteolysis. Components of the MSP-1/6/7 complex and AMA-1 are presently under development as malaria vaccines. METHODS The specificities and effects of antibodies directed against MSP-1, MSP-6, MSP-7 on the growth of blood stage parasites were studied using ELISA and the pLDH-assay. To understand the mode of action of these antibodies, their effects on processing of MSP-1 and AMA-1 on the surface of merozoites were investigated. RESULTS Antibodies targeting epitopes located throughout the MSP-1/6/7 complex interfere with shedding of MSP-1, and as a consequence prevent erythrocyte invasion. Antibodies targeting the MSP-1/6/7 complex have no effect on the processing and shedding of AMA-1 and, similarly, antibodies blocking the shedding of AMA-1 do not affect cleavage of MSP-1, suggesting completely independent functions of these proteins during invasion. Furthermore, some epitopes, although eliciting highly inhibitory antibodies, are only poorly recognized by the immune system when presented in the structural context of the intact antigen. CONCLUSIONS The findings reported provide further support for the development of vaccines based on MSP-1/6/7 and AMA-1, which would possibly include a combination of these antigens.
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Affiliation(s)
- Ute Woehlbier
- Zentrum für Molekulare Biologie (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
- Current address: Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia 23298-0678, USA
| | - Christian Epp
- Zentrum für Molekulare Biologie (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
- Current address: Department of Infectious Diseases, Parasitology, School of Medicine, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
| | - Fiona Hackett
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Michael J Blackman
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Hermann Bujard
- Zentrum für Molekulare Biologie (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Abstract
Malaria remains one of the most devastating infectious diseases that threaten humankind. Human malaria is caused by five different species of Plasmodium parasites, each transmitted by the bite of female Anopheles mosquitoes. Plasmodia are eukaryotic protozoans with more than 5000 genes and a complex life cycle that takes place in the mosquito vector and the human host. The life cycle can be divided into pre-erythrocytic stages, erythrocytic stages and mosquito stages. Malaria vaccine research and development faces formidable obstacles because many vaccine candidates will probably only be effective in a specific species at a specific stage. In addition, Plasmodium actively subverts and escapes immune responses, possibly foiling vaccine-induced immunity. Although early successful vaccinations with irradiated, live-attenuated malaria parasites suggested that a vaccine is possible, until recently, most efforts have focused on subunit vaccine approaches. Blood-stage vaccines remain a primary research focus, but real progress is evident in the development of a partially efficacious recombinant pre-erythrocytic subunit vaccine and a live-attenuated sporozoite vaccine. It is unlikely that partially effective vaccines will eliminate malaria; however, they might prove useful in combination with existing control strategies. Elimination of malaria will probably ultimately depend on the development of highly effective vaccines.
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Humoral immune response to mixed PfAMA1 alleles; multivalent PfAMA1 vaccines induce broad specificity. PLoS One 2009; 4:e8110. [PMID: 19956619 PMCID: PMC2779588 DOI: 10.1371/journal.pone.0008110] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Accepted: 11/04/2009] [Indexed: 11/19/2022] Open
Abstract
Apical Membrane Antigen 1 (AMA1), a merozoite protein essential for red cell invasion, is a candidate malaria vaccine component. Immune responses to AMA1 can protect in experimental animal models and antibodies isolated from AMA1-vaccinated or malaria-exposed humans can inhibit parasite multiplication in vitro. The parasite is haploid in the vertebrate host and the genome contains a single copy of AMA1, yet on a population basis a number of AMA1 molecular surface residues are polymorphic, a property thought to be primarily as a result of selective immune pressure. After immunisation with AMA1, antibodies more effectively inhibit strains carrying homologous AMA1 genes, suggesting that polymorphism may compromise vaccine efficacy. Here, we analyse induction of broad strain inhibitory antibodies with a multi-allele Plasmodium falciparum AMA1 (PfAMA1) vaccine, and determine the relative importance of cross-reactive and strain-specific IgG fractions by competition ELISA and in vitro parasite growth inhibition assays. Immunisation of rabbits with a PfAMA1 allele mixture yielded an increased proportion of antibodies to epitopes common to all vaccine alleles, compared to single allele immunisation. Competition ELISA with the anti-PfAMA1 antibody fraction that is cross-reactive between FVO and 3D7 AMA1 alleles showed that over 80% of these common antibodies were shared with other PfAMA1 alleles. Furthermore, growth inhibition assays revealed that for any PfAMA1 allele (FVO or 3D7), the cross-reactive fraction alone, on basis of weight, had the same functional capacity on homologous parasites as the total affinity-purified IgGs (cross-reactive+strain-specific). By contrast, the strain-specific IgG fraction of either PfAMA1 allele showed slightly less inhibition of red cell invasion by homologous strains. Thus multi-allele immunisation relatively increases the levels of antibodies to common allele epitopes. This explains the broadened cross inhibition of diverse malaria parasites, and suggests multi-allele approaches warrant further clinical investigation.
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Alanine mutagenesis of the primary antigenic escape residue cluster, c1, of apical membrane antigen 1. Infect Immun 2009; 78:661-71. [PMID: 19948834 DOI: 10.1128/iai.00866-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antibodies against apical membrane antigen 1 (AMA1) inhibit invasion of Plasmodium merozoites into red cells, and a large number of single nucleotide polymorphisms on AMA1 allow the parasite to escape inhibitory antibodies. The availability of a crystal structure makes it possible to test protein engineering strategies to develop a monovalent broadly reactive vaccine. Previously, we showed that a linear stretch of polymorphic residues (amino acids 187 to 207), localized within the C1 cluster on domain 1, conferred the highest level of escape from inhibitory antibodies, and these were termed antigenic escape residues (AER). Here we test the hypothesis that immunodampening the C1 AER will divert the immune system toward more conserved regions. We substituted seven C1 AER of the FVO strain Plasmodium falciparum AMA1 with alanine residues (ALA). The resulting ALA protein was less immunogenic than the native protein in rabbits. Anti-ALA antibodies contained a higher proportion of cross-reactive domain 2 and domain 3 antibodies and had higher avidity than anti-FVO. No overall enhancement of cross-reactive inhibitory activity was observed when anti-FVO and anti-ALA sera were compared for their ability to inhibit invasion. Alanine mutations at the C1 AER had shifted the immune response toward cross-strain-reactive epitopes that were noninhibitory, refuting the hypothesis but confirming the importance of the C1 cluster as an inhibitory epitope. We further demonstrate that naturally occurring polymorphisms that fall within the C1 cluster can predict escape from cross-strain invasion inhibition, reinforcing the importance of the C1 cluster genotype for antigenic categorization and allelic shift analyses in future phase 2b trials.
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Treeck M, Tamborrini M, Daubenberger CA, Gilberger TW, Voss TS. Caught in action: mechanistic insights into antibody-mediated inhibition of Plasmodium merozoite invasion. Trends Parasitol 2009; 25:494-7. [DOI: 10.1016/j.pt.2009.07.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 07/20/2009] [Accepted: 07/31/2009] [Indexed: 11/29/2022]
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Bhattacharyya A, Babu CR. Purification and biochemical characterization of a serine proteinase inhibitor from Derris trifoliata Lour. seeds: insight into structural and antimalarial features. PHYTOCHEMISTRY 2009; 70:703-712. [PMID: 19409579 DOI: 10.1016/j.phytochem.2009.04.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 04/02/2009] [Indexed: 05/27/2023]
Abstract
A potent serine proteinase inhibitor was isolated and characterized from the seeds of the tropical legume liana, Derris trifoliata (DtTCI) by ammonium sulfate precipitation, ion exchange chromatography and gel filtration chromatography. SDS-PAGE as well as MALDI-TOF analysis showed that DtTCI is a single polypeptide chain with a molecular mass of approximately 20 kDa. DtTCI has three isoinhibitors (pI: 4.55, 5.34 and 5.72) and, inhibited both trypsin and chymotrypsin in a 1:1 molar ratio. Both Dixon plots and Lineweaver-Burk double reciprocal plots revealed a competitive inhibition of trypsin and chymotrypsin activity, with inhibition constants (K(i)) of 1.7x10(-10) and 1.25x10(-10) M, respectively. N-terminal sequence of DtTCI showed over 50% similarity with numerous Kunitz-type inhibitors of the Papilionoideae subfamily. High pH amplitude and broad temperature optima were noted for DtTCI, and time course experiments indicated a gradual loss in inhibitory potency on treatment with dithiothreitol (DTT). Circular Dichroism (CD) spectrum of native DtTCI revealed an unordered structure whereas exposure to thermal-pH extremes, DTT and guanidine hydrochloride (Gdn HCl) suggested that an abundance of beta-sheets along with intramolecular disulfide bonds provide conformational stability to the active site of DtTCI, and that severity of denaturants cause structural modifications promoting inhibitory inactivity. Antimalarial studies of DtTCI indicate it to be a potent antiparasitic agent.
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Affiliation(s)
- Arindam Bhattacharyya
- Centre for Environmental Management of Degraded Ecosystems, School of Environmental Studies, University of Delhi, Delhi, India.
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Harris KS, Casey JL, Coley AM, Karas JA, Sabo JK, Tan YY, Dolezal O, Norton RS, Hughes AB, Scanlon D, Foley M. Rapid optimization of a peptide inhibitor of malaria parasite invasion by comprehensive N-methyl scanning. J Biol Chem 2009; 284:9361-71. [PMID: 19164290 DOI: 10.1074/jbc.m808762200] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apical membrane antigen 1 (AMA1) of the malaria parasite Plasmodium falciparum has been implicated in the invasion of host erythrocytes and is an important vaccine candidate. We have previously described a 20-residue peptide, R1, that binds to AMA1 and subsequently blocks parasite invasion. Because this peptide appears to target a site critical for AMA1 function, it represents an important lead compound for anti-malarial drug development. However, the effectiveness of this peptide inhibitor was limited to a subset of parasite isolates, indicating a requirement for broader strain specificity. Furthermore, a barrier to the utility of any peptide as a potential therapeutic is its susceptibility to rapid proteolytic degradation. In this study, we sought to improve the proteolytic stability and AMA1 binding properties of the R1 peptide by systematic methylation of backbone amides (N-methylation). The inclusion of a single N-methyl group in the R1 peptide backbone dramatically increased AMA1 affinity, bioactivity, and proteolytic stability without introducing global structural alterations. In addition, N-methylation of multiple R1 residues further improved these properties. Therefore, we have shown that modifications to a biologically active peptide can dramatically enhance activity. This approach could be applied to many lead peptides or peptide therapeutics to simultaneously optimize a number of parameters.
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Affiliation(s)
- Karen S Harris
- Department of Biochemistry, La Trobe University, Victoria 3086, Australia
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40
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Collins CR, Withers-Martinez C, Hackett F, Blackman MJ. An inhibitory antibody blocks interactions between components of the malarial invasion machinery. PLoS Pathog 2009; 5:e1000273. [PMID: 19165323 PMCID: PMC2621342 DOI: 10.1371/journal.ppat.1000273] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 12/16/2008] [Indexed: 11/18/2022] Open
Abstract
Host cell invasion by apicomplexan pathogens such as the malaria parasite Plasmodium spp. and Toxoplasma gondii involves discharge of proteins from secretory organelles called micronemes and rhoptries. In Toxoplasma a protein complex comprising the microneme apical membrane antigen 1 (AMA1), two rhoptry neck proteins, and a protein called Ts4705, localises to the moving junction, a region of close apposition between parasite and host cell during invasion. Antibodies against AMA1 prevent invasion and are protective in vivo, and so AMA1 is of widespread interest as a malaria vaccine candidate. Here we report that the AMA1 complex identified in Toxoplasma is conserved in Plasmodium falciparum. We demonstrate that the invasion-inhibitory monoclonal antibody (mAb) 4G2, which recognises P. falciparum AMA1 (PfAMA1), cannot bind when PfAMA1 is in a complex with its partner proteins. We further show that a single completely conserved PfAMA1 residue, Tyr251, lying within a conserved hydrophobic groove adjacent to the mAb 4G2 epitope, is required for complex formation. We propose that mAb 4G2 inhibits invasion by preventing PfAMA1 from interacting with other components of the invasion complex. Our findings should aid the rational design of subunit malaria vaccines based on PfAMA1.
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Affiliation(s)
- Christine R. Collins
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London, United Kingdom
| | | | - Fiona Hackett
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London, United Kingdom
| | - Michael J. Blackman
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London, United Kingdom
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Abstract
In this chapter, we outline the tools and techniques available to study the process of host cell invasion by apicomplexan parasites and we provide specific examples of how these methods have been used to further our understanding of apicomplexan invasive mechanisms. Throughout the chapter we focus our discussion on Toxoplasmagondii, because T. gondii is the most experimentally accessible model organism for studying apicomplexan invasion (discussed further in the section, "Toxoplasma as a Model Apicomplexan") and more is known about invasion in T. gondii than in any other apicomplexan.
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Abstract
The development and implementation of a malaria vaccine would constitute a major breakthrough for global health. Recently, numerous new candidates have entered clinical testing, following strategies that are as diverse as the malaria cycle is complex. While promising results have been obtained, some candidate vaccines have not fulfilled expectations. The challenges are not merely scientific; further progresses will require the development of competent investigator networks, partnerships between academics, industry and funding agencies, and continuous political commitment. In this review, we present the developmental status of all malaria vaccine candidates that are currently in human clinical testing against Plasmodium falciparum, as well as selected malaria vaccine candidates at preclinical development stage, and discuss the main challenges facing the field of malaria vaccine development.
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Affiliation(s)
- Johan Vekemans
- GlaxoSmithKline Biologicals, Emerging Diseases, Global Clinical Research and Development Vaccines, Rixensart, Belgium.
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43
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Henderson KA, Streltsov VA, Coley AM, Dolezal O, Hudson PJ, Batchelor AH, Gupta A, Bai T, Murphy VJ, Anders RF, Foley M, Nuttall SD. Structure of an IgNAR-AMA1 complex: targeting a conserved hydrophobic cleft broadens malarial strain recognition. Structure 2008; 15:1452-66. [PMID: 17997971 DOI: 10.1016/j.str.2007.09.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2007] [Revised: 08/13/2007] [Accepted: 09/10/2007] [Indexed: 11/18/2022]
Abstract
Apical membrane antigen 1 (AMA1) is essential for invasion of erythrocytes and hepatocytes by Plasmodium parasites and is a leading malarial vaccine candidate. Although conventional antibodies to AMA1 can prevent such invasion, extensive polymorphisms within surface-exposed loops may limit the ability of these AMA1-induced antibodies to protect against all parasite genotypes. Using an AMA1-specific IgNAR single-variable-domain antibody, we performed targeted mutagenesis and selection against AMA1 from three P. falciparum strains. We present cocrystal structures of two antibody-AMA1 complexes which reveal extended IgNAR CDR3 loops penetrating deep into a hydrophobic cleft on the antigen surface and contacting residues conserved across parasite species. Comparison of a series of affinity-enhancing mutations allowed dissection of their relative contributions to binding kinetics and correlation with inhibition of erythrocyte invasion. These findings provide insights into mechanisms of single-domain antibody binding, and may enable design of reagents targeting otherwise cryptic epitopes in pathogen antigens.
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Affiliation(s)
- Kylie A Henderson
- CSIRO Molecular and Health Technologies, 343 Royal Parade, Parkville 3052, Australia
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Remarque EJ, Faber BW, Kocken CHM, Thomas AW. Apical membrane antigen 1: a malaria vaccine candidate in review. Trends Parasitol 2008; 24:74-84. [PMID: 18226584 DOI: 10.1016/j.pt.2007.12.002] [Citation(s) in RCA: 222] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Revised: 10/31/2007] [Accepted: 12/20/2007] [Indexed: 10/22/2022]
Abstract
Apical membrane antigen 1 (AMA1) is a micronemal protein of apicomplexan parasites that appears to be essential during the invasion of host cells. Immune responses to Plasmodium AMA1 can have profound parasite-inhibitory effects, both as measured in vitro and in animal challenge models, suggesting AMA1 as a potential vaccine component. However, AMA1 is polymorphic, probably as a result of immune selection operating on an important target of naturally occurring immunity. The current understanding of AMA1 will be presented, particularly in relation to the vaccine potential of AMA1 and the approaches being taken towards clinical development.
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Affiliation(s)
- Edmond J Remarque
- Department of Parasitology, Biomedical Primate Research Centre, 2280 GH Rijswijk, The Netherlands
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45
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Bueno LL, Fujiwara RT, Soares IS, Braga EM. Direct effect of Plasmodium vivax recombinant vaccine candidates AMA-1 and MSP-119 on the innate immune response. Vaccine 2008; 26:1204-13. [PMID: 18242795 DOI: 10.1016/j.vaccine.2007.12.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Revised: 12/15/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
Abstract
The recombinant apical membrane antigen 1 (AMA-1) and 19-kDa fragment of merozoite surface protein (MSP-1(19)) are the lead candidates for inclusion in a vaccine against blood stages of malaria due to encouraging protective studies in humans and animals. Despite the importance of an efficacious malaria vaccine, vaccine-related research has focused on identifying antigens that result in protective immunity rather than determining the nature of anti-malarial immune effector mechanisms. Moreover, emphasis has been placed on adaptive rather than innate immune responses. In this study, we investigated the effect of Plasmodium vivax vaccine candidates Pv-AMA-1 and Pv-MSP-1(19) on the immune response of malaria-naïve donors. Maturation of dendritic cells is altered by Pv-AMA-1 but not Pv-MSP-1(19), as observed by differential expression of cell surface markers. In addition, Pv-AMA-1 induced an increased production of MIP-1alpha/CCL3 and decreased production of TARC/CCL17 levels in both dendritic cells (DCs) and peripheral blood mononuclear cells (PBMCs). Finally, a significant pro-inflammatory response was elicited by Pv-AMA-1-stimulated PBMCs. These results suggest that the recombinant vaccine candidate Pv-AMA-1 may play a direct role on innate immune response and might be involved in parasite destruction.
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Affiliation(s)
- Lilian Lacerda Bueno
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte (MG), Brazil
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46
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Dowse TJ, Koussis K, Blackman MJ, Soldati-Favre D. Roles of proteases during invasion and egress by Plasmodium and Toxoplasma. Subcell Biochem 2008; 47:121-39. [PMID: 18512347 DOI: 10.1007/978-0-387-78267-6_10] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Apicomplexan pathogens replicate exclusively within the confines of a host cell. Entry into (invasion) and exit from (egress) these cells requires an array of specialized parasite molecules, many of which have long been considered to have potential as targets of drug or vaccine-based therapies. In this chapter the authors discuss the current state of knowledge regarding the role of parasite proteolytic enzymes in these critical steps in the life cycle of two clinically important apicomplexan genera, Plasmodium and Toxoplasma. At least three distinct proteases of the cysteine mechanistic class have been implicated in egress of the malaria parasite from cells of its vertebrate and insect host. In contrast, the bulk of the evidence indicates a prime role for serine proteases of the subtilisin and rhomboid families in invasion by both parasites. Whereas proteases involved in egress may function predominantly to degrade host cell structures, proteases involved in invasion probably act primarily as maturases and 'sheddases', required to activate and ultimately remove ligands involved in interactions with the host cell.
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Affiliation(s)
- Timothy J Dowse
- Department of Biological Sciences, Imperial College, London, UK
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47
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Coley AM, Gupta A, Murphy VJ, Bai T, Kim H, Anders RF, Foley M, Batchelor AH. Structure of the malaria antigen AMA1 in complex with a growth-inhibitory antibody. PLoS Pathog 2007; 3:1308-19. [PMID: 17907804 PMCID: PMC2323298 DOI: 10.1371/journal.ppat.0030138] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Accepted: 08/02/2007] [Indexed: 11/19/2022] Open
Abstract
Identifying functionally critical regions of the malaria antigen AMA1 (apical membrane antigen 1) is necessary to understand the significance of the polymorphisms within this antigen for vaccine development. The crystal structure of AMA1 in complex with the Fab fragment of inhibitory monoclonal antibody 1F9 reveals that 1F9 binds to the AMA1 solvent-exposed hydrophobic trough, confirming its importance. 1F9 uses the heavy and light chain complementarity-determining regions (CDRs) to wrap around the polymorphic loops adjacent to the trough, but uses a ridge of framework residues to bind to the hydrophobic trough. The resulting 1F9-AMA1–combined buried surface of 2,470 Å2 is considerably larger than previously reported Fab–antigen interfaces. Mutations of polymorphic AMA1 residues within the 1F9 epitope disrupt 1F9 binding and dramatically reduce the binding of affinity-purified human antibodies. Moreover, 1F9 binding to AMA1 is competed by naturally acquired human antibodies, confirming that the 1F9 epitope is a frequent target of immunological attack. Malaria caused by Plasmodium falciparum causes more than 1 million deaths annually, and the development of a vaccine against this parasite is a major public health priority. Development of a vaccine is considered feasible because infection with malaria parasites induces protective immune responses, which include antibodies to a range of proteins on the parasite surface. Antigenic diversity allows the parasite to evade protective responses, and this may make it difficult to develop a vaccine that is effective against most infections. To facilitate the design of an effective vaccine, a more detailed understanding of how antibodies interact with their target parasite antigens is required. Here, we provide a detailed structural picture of the interaction between a growth-inhibitory monoclonal antibody and the leading vaccine candidate, AMA1. The results provide important insights into why some antibodies are inhibitory and why antigenic diversity in AMA1 enables the parasite to evade protective antibody responses.
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Affiliation(s)
- Andrew M Coley
- Cooperative Research Center for Diagnostics, Department of Biochemistry, La Trobe University, Victoria, Australia
- Department of Biochemistry, La Trobe University, Victoria, Australia
| | - Aditi Gupta
- University of Maryland School of Pharmacy, Baltimore, Maryland, United States of America
| | - Vince J Murphy
- Department of Biochemistry, La Trobe University, Victoria, Australia
| | - Tao Bai
- University of Maryland School of Pharmacy, Baltimore, Maryland, United States of America
| | - Hanna Kim
- University of Maryland School of Pharmacy, Baltimore, Maryland, United States of America
| | - Robin F Anders
- Department of Biochemistry, La Trobe University, Victoria, Australia
| | - Michael Foley
- Cooperative Research Center for Diagnostics, Department of Biochemistry, La Trobe University, Victoria, Australia
- Department of Biochemistry, La Trobe University, Victoria, Australia
- * To whom correspondence should be addressed. E-mail: (MF); (AHB)
| | - Adrian H Batchelor
- University of Maryland School of Pharmacy, Baltimore, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail: (MF); (AHB)
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48
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Dutta S, Lee SY, Batchelor AH, Lanar DE. Structural basis of antigenic escape of a malaria vaccine candidate. Proc Natl Acad Sci U S A 2007; 104:12488-93. [PMID: 17636123 PMCID: PMC1941496 DOI: 10.1073/pnas.0701464104] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antibodies against the malaria vaccine candidate apical membrane antigen-1 (AMA-1) can inhibit invasion of merozoites into RBC, but antigenic diversity can compromise vaccine efficacy. We hypothesize that polymorphic sites located within inhibitory epitopes function as antigenic escape residues (AER). By using an in vitro model of antigenic escape, the inhibitory contribution of 24 polymorphic sites of the 3D7 AMA-1 vaccine was determined. An AER cluster of 13 polymorphisms, located within domain 1, had the highest inhibitory contribution. Within this AER cluster, antibodies primarily targeted five polymorphic residues situated on an alpha-helical loop. A second important AER cluster was localized to domain 2. Domain 3 polymorphisms enhanced the inhibitory contribution of the domain 2 AER cluster. Importantly, the AER clusters could be split, such that chimeras containing domain 1 of FVO and domain 2 + 3 of 3D7 generated antisera that showed similarly high level inhibition of the two vaccine strains. Antibodies to this chimeric protein also inhibited unrelated strains of the parasite. Interstrain AER chimeras can be a way to incorporate inhibitory epitopes of two AMA-1 strains into a single protein. The AER clusters map in close proximity to conserved structural elements: the hydrophobic trough and the C-terminal proteolytic processing site. This finding led us to hypothesize that a conserved structural basis of antigenic escape from anti-AMA-1 exists. Genotyping high-impact AER may be useful for classifying AMA-1 strains into inhibition groups and to detect allelic effects of an AMA-1 vaccine in the field.
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Affiliation(s)
- Sheetij Dutta
- Department of Epitope Mapping, Division of Malaria Vaccine Development, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
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49
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Polhemus ME, Magill AJ, Cummings JF, Kester KE, Ockenhouse CF, Lanar DE, Dutta S, Barbosa A, Soisson L, Diggs CL, Robinson SA, Haynes JD, Stewart VA, Ware LA, Brando C, Krzych U, Bowden RA, Cohen JD, Dubois MC, Ofori-Anyinam O, De-Kock E, Ballou WR, Heppner DG. Phase I dose escalation safety and immunogenicity trial of Plasmodium falciparum apical membrane protein (AMA-1) FMP2.1, adjuvanted with AS02A, in malaria-naïve adults at the Walter Reed Army Institute of Research. Vaccine 2007; 25:4203-12. [PMID: 17442466 DOI: 10.1016/j.vaccine.2007.03.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Revised: 02/21/2007] [Accepted: 03/02/2007] [Indexed: 11/26/2022]
Abstract
We report the first safety and immunogenicity trial of the Plasmodium falciparum vaccine candidate FMP2.1/AS02A, a recombinant E. coli-expressed protein based upon the apical membrane antigen-1 (AMA-1) of the 3D7 clone formulated with the AS02A adjuvant. We conducted an open-label, staggered-start, dose-escalating Phase I trial in 23 malaria-naïve volunteers who received 8, 20 or 40microg of FMP2.1 in a fixed volume of 0.5mL of AS02A on a 0, 1, and 2 month schedule. Nineteen of 23 volunteers received all three scheduled immunizations. The most frequent solicited local and systemic adverse events associated with immunization were injection site pain (68%) and headache (29%). There were no significant laboratory abnormalities or vaccine-related serious adverse events. All volunteers seroconverted after second immunization as determined by ELISA. Immune sera recognized sporozoites and merozoites by immunofluorescence assay (IFA), and exhibited both growth inhibition and processing inhibition activity against homologous (3D7) asexual stage parasites. Post-immunization, peripheral blood mononuculear cells exhibited FMP2.1-specific lymphoproliferation and IFN-gamma and IL-5 ELISPOT assay responses. This is the first PfAMA-1-based vaccine shown to elicit both potent humoral and cellular immunity in humans. Encouraged by the potential of FMP1/AS02A to target host immunity against PfAMA-1 that is known to be expressed by sporozoite, hepatic and erythrocytic stages, we have initiated field trials of FMP2.1/AS02A in an endemic population in the Republic of Mali.
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Affiliation(s)
- Mark E Polhemus
- Walter Reed Army Institute of Research, Silver Spring, MD, United States.
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50
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Collins CR, Withers-Martinez C, Bentley GA, Batchelor AH, Thomas AW, Blackman MJ. Fine mapping of an epitope recognized by an invasion-inhibitory monoclonal antibody on the malaria vaccine candidate apical membrane antigen 1. J Biol Chem 2007; 282:7431-41. [PMID: 17192270 DOI: 10.1074/jbc.m610562200] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antibodies that inhibit red blood cell invasion by the Plasmodium merozoite block the erythrocytic cycle responsible for clinical malaria. The invasion-inhibitory monoclonal antibody (mAb) 4G2 recognizes a conserved epitope in the ectodomain of the essential Plasmodium falciparum microneme protein and vaccine candidate, apical membrane antigen 1 (PfAMA1). Here we demonstrate that purified Fab fragments of 4G2 inhibit invasion markedly more efficiently than the intact mAb, suggesting that the invasion-inhibitory activity of this mAb is not due solely to steric effects and that the epitope lies within a functionally critical region of the molecule. We have taken advantage of a synthetic gene encoding a modified form of PfAMA1, and existing x-ray crystal structure data, to fully characterize this epitope. We first validate the gene by demonstrating that it fully complements the function of the authentic gene in P. falciparum. We then use it to identify a group of residues within the previously described domain II loop of PfAMA1 that are critical for recognition by mAb 4G2 and demonstrate that the epitope lies exclusively within this loop with no contributions from residues in other domains of the molecule. This is the first complete characterization of a conserved invasion-inhibitory epitope on PfAMA1. Our results will aid in the design of subunit vaccines designed to generate a broadly effective, focused anti-PfAMA1 protective immune response and may help elucidate the function of PfAMA1.
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Affiliation(s)
- Christine R Collins
- Division of Parasitology, National Institute for Medical Research, Mill Hill, London NW7 1AA, United Kingdom
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