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Zuo S, Lu J, Sun Y, Song J, Han S, Feng X, Han ET, Cheng Y. The Plasmodium vivax MSP1P-19 is involved in binding of reticulocytes through interactions with the membrane proteins band3 and CD71. J Biol Chem 2024; 300:107285. [PMID: 38636656 PMCID: PMC11107369 DOI: 10.1016/j.jbc.2024.107285] [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: 01/14/2024] [Revised: 03/26/2024] [Accepted: 03/29/2024] [Indexed: 04/20/2024] Open
Abstract
The parasite Plasmodium vivax preferentially invades human reticulocytes. Its merozoite surface protein 1 paralog (PvMSP1P), particularly the 19-kDa C-terminal region (PvMSP1P-19), has been shown to bind to reticulocytes, and this binding can be inhibited by antisera obtained by PvMSP1P-19 immunization. The molecular mechanism of interactions between PvMSP1P-19 and reticulocytes during P. vivax invasion, however, remains unclear. In this study, we analyzed the ability of MSP1P-19 to bind to different concentrations of reticulocytes and confirmed its reticulocyte preference. LC-MS analysis was used to identify two potential reticulocyte receptors, band3 and CD71, that interact with MSP1P-19. Both PvMSP1P-19 and its sister taxon Plasmodium cynomolgi MSP1P-19 were found to bind to the extracellular loop (loop 5) of band3, where the interaction of MSP1P-19 with band3 was chymotrypsin sensitive. Antibodies against band3-P5, CD71, and MSP1P-19 reduced the binding activity of PvMSP1P-19 and Plasmodium cynomolgi MSP1P-19 to reticulocytes, while MSP1P-19 proteins inhibited Plasmodium falciparum invasion in vitro in a concentration-dependent manner. To sum up, identification and characterization of the reticulocyte receptor is important for understanding the binding of reticulocytes by MSP1P-19.
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Affiliation(s)
- Shenghuan Zuo
- Laboratory of Pathogen Infection and Immunity, Department of Clinical Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Jiachen Lu
- Laboratory of Pathogen Infection and Immunity, Department of Clinical Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Yifan Sun
- Laboratory of Pathogen Infection and Immunity, Department of Clinical Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China; Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Jing Song
- Affiliated Hospital of Jiangnan University, Wuxi, Jiangsu, China
| | - Su Han
- Laboratory of Pathogen Infection and Immunity, Department of Clinical Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Xin Feng
- Laboratory of Pathogen Infection and Immunity, Department of Clinical Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China
| | - Eun-Taek Han
- Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, Republic of Korea
| | - Yang Cheng
- Laboratory of Pathogen Infection and Immunity, Department of Clinical Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu, China.
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Natama HM, Moncunill G, Vidal M, Rouamba T, Aguilar R, Santano R, Rovira-Vallbona E, Jiménez A, Somé MA, Sorgho H, Valéa I, Coulibaly-Traoré M, Coppel RL, Cavanagh D, Chitnis CE, Beeson JG, Angov E, Dutta S, Gamain B, Izquierdo L, Mens PF, Schallig HDFH, Tinto H, Rosanas-Urgell A, Dobaño C. Associations between prenatal malaria exposure, maternal antibodies at birth, and malaria susceptibility during the first year of life in Burkina Faso. Infect Immun 2023; 91:e0026823. [PMID: 37754682 PMCID: PMC10580994 DOI: 10.1128/iai.00268-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 08/12/2023] [Indexed: 09/28/2023] Open
Abstract
In this study, we investigated how different categories of prenatal malaria exposure (PME) influence levels of maternal antibodies in cord blood samples and the subsequent risk of malaria in early childhood in a birth cohort study (N = 661) nested within the COSMIC clinical trial (NCT01941264) in Burkina Faso. Plasmodium falciparum infections during pregnancy and infants' clinical malaria episodes detected during the first year of life were recorded. The levels of maternal IgG and IgG1-4 to 15 P. falciparum antigens were measured in cord blood by quantitative suspension array technology. Results showed a significant variation in the magnitude of maternal antibody levels in cord blood, depending on the PME category, with past placental malaria (PM) more frequently associated with significant increases of IgG and/or subclass levels across three groups of antigens defined as pre-erythrocytic, erythrocytic, and markers of PM, as compared to those from the cord of non-exposed control infants. High levels of antibodies to certain erythrocytic antigens (i.e., IgG to EBA140 and EBA175, IgG1 to EBA175 and MSP142, and IgG3 to EBA140 and MSP5) were independent predictors of protection from clinical malaria during the first year of life. By contrast, high levels of IgG, IgG1, and IgG2 to the VAR2CSA DBL1-2 and IgG4 to DBL3-4 were significantly associated with an increased risk of clinical malaria. These findings indicate that PME categories have different effects on the levels of maternal-derived antibodies to malaria antigens in children at birth, and this might drive heterogeneity to clinical malaria susceptibility in early childhood.
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Affiliation(s)
- Hamtandi Magloire Natama
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Gemma Moncunill
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
| | - Marta Vidal
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
| | - Toussaint Rouamba
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Ruth Aguilar
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
| | - Rebeca Santano
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
| | - Eduard Rovira-Vallbona
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
| | - Alfons Jiménez
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Epidemiologia y Salud Pública (CIBERESP), Barcelona, Spain
| | - M. Athanase Somé
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Hermann Sorgho
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Innocent Valéa
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Maminata Coulibaly-Traoré
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Ross L. Coppel
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - David Cavanagh
- Centre for Immunity, Infection & Evolution, Institute of Immunology & Infection Research, Ashworth Laboratories, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Chetan E. Chitnis
- Malaria Parasite Biology and Vaccines Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Université de Paris, Paris, France
| | | | - Evelina Angov
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | - Sheetij Dutta
- U.S. Military Malaria Vaccine Program, Walter Reed Army Institute of Research (WRAIR), Silver Spring, Maryland, USA
| | | | - Luis Izquierdo
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
| | - Petra F. Mens
- Academic Medical Centre at the University of Amsterdam, Amsterdam, the Netherlands
| | | | - Halidou Tinto
- Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Direction Régionale du Centre-Ouest, Nanoro, Burkina Faso
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Carlota Dobaño
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic – Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Infecciosas (CIBERINFEC), Barcelona, Spain
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3
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Plasmodium knowlesi Duffy binding protein alpha region II (PkDBPαII) in clinical isolates from Peninsular Malaysia and Malaysian Borneo exhibit different immune responses in animal models. Parasitol Res 2022; 121:3443-3454. [PMID: 36152079 DOI: 10.1007/s00436-022-07665-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 09/09/2022] [Indexed: 10/14/2022]
Abstract
Plasmodium knowlesi utilizes the Duffy binding protein alpha (PkDBPα) to facilitate its invasion into human erythrocytes. PkDBPα region II (PkDBPαII) from Peninsular Malaysia and Malaysian Borneo has been shown to occur as distinct haplotypes, and the predominant haplotypes from these geographical areas demonstrated differences in binding activity to human erythrocytes in erythrocyte binding assays. This study aimed to determine the effects of genetic polymorphisms in PkDBPαII to immune responses in animal models. The recombinant PkDBPαII (~ 45 kDa) of Peninsular Malaysia (PkDBPαII-H) and Malaysian Borneo (PkDBPαII-S) were expressed in a bacterial expression system, purified, and used in mice and rabbit immunization. The profile of cytokines IL-1ra, IL-2, IL-6, IL-10, TNF-α, and IFN-γ in immunized mice spleen was determined via ELISA. The titer and IgG subtype distribution of raised antibodies was characterized. Immunized rabbit sera were purified and used to perform an in vitro merozoite invasion inhibition assay. The PkDBPαII-immunized mice sera of both groups showed high antibody titer and a similar IgG subtype distribution pattern: IgG2b > IgG1 > IgG2a > IgG3. The PkDBPαII-H group was shown to have higher IL-1ra (P = 0.141) and IL-6 (P = 0.049) concentrations, with IL-6 levels significantly higher than that of the PkDBPαII-S group (P ≤ 0.05). Merozoite invasion inhibition assay using purified anti-PkDBPαII antibodies showed a significantly higher inhibition rate in the PkDBPαII-H group than the PkDBPαII-S group (P ≤ 0.05). Besides, anti-PkDBPαII-H antibodies were able to exhibit inhibition activity at a lower concentration than anti-PkDBPαII-S antibodies. PkDBPαII was shown to be immunogenic, and the PkDBPαII haplotype from Peninsular Malaysia exhibited higher responses in cytokines IL-1ra and IL-6, antibody IgM level, and merozoite invasion inhibition assay than the Malaysian Borneo haplotype. This suggests that polymorphisms in the PkDBPαII affect the level of immune responses in the host.
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4
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Molina-Franky J, Patarroyo ME, Kalkum M, Patarroyo MA. The Cellular and Molecular Interaction Between Erythrocytes and Plasmodium falciparum Merozoites. Front Cell Infect Microbiol 2022; 12:816574. [PMID: 35433504 PMCID: PMC9008539 DOI: 10.3389/fcimb.2022.816574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/21/2022] [Indexed: 11/13/2022] Open
Abstract
Plasmodium falciparum is the most lethal human malaria parasite, partly due to its genetic variability and ability to use multiple invasion routes via its binding to host cell surface receptors. The parasite extensively modifies infected red blood cell architecture to promote its survival which leads to increased cell membrane rigidity, adhesiveness and permeability. Merozoites are initially released from infected hepatocytes and efficiently enter red blood cells in a well-orchestrated process that involves specific interactions between parasite ligands and erythrocyte receptors; symptoms of the disease occur during the life-cycle’s blood stage due to capillary blockage and massive erythrocyte lysis. Several studies have focused on elucidating molecular merozoite/erythrocyte interactions and host cell modifications; however, further in-depth analysis is required for understanding the parasite’s biology and thus provide the fundamental tools for developing prophylactic or therapeutic alternatives to mitigate or eliminate Plasmodium falciparum-related malaria. This review focuses on the cellular and molecular events during Plasmodium falciparum merozoite invasion of red blood cells and the alterations that occur in an erythrocyte once it has become infected.
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Affiliation(s)
- Jessica Molina-Franky
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- Department of Immunology and Theranostics, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute of the City of Hope, Duarte, CA, United States
- PhD Programme in Biotechnology, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Manuel Elkin Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- Health Sciences Division, Universidad Santo Tomás, Bogotá, Colombia
- Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
| | - Markus Kalkum
- Department of Immunology and Theranostics, Arthur Riggs Diabetes and Metabolism Research Institute, Beckman Research Institute of the City of Hope, Duarte, CA, United States
- *Correspondence: Markus Kalkum, ; Manuel Alfonso Patarroyo,
| | - Manuel Alfonso Patarroyo
- Molecular Biology and Immunology Department, Fundación Instituto de Inmunología de Colombia (FIDIC), Bogotá, Colombia
- Health Sciences Division, Universidad Santo Tomás, Bogotá, Colombia
- Faculty of Medicine, Universidad Nacional de Colombia, Bogotá, Colombia
- *Correspondence: Markus Kalkum, ; Manuel Alfonso Patarroyo,
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5
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Hotspots in Plasmodium and RBC Receptor-Ligand Interactions: Key Pieces for Inhibiting Malarial Parasite Invasion. Int J Mol Sci 2020; 21:ijms21134729. [PMID: 32630804 PMCID: PMC7370042 DOI: 10.3390/ijms21134729] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/15/2020] [Accepted: 05/24/2020] [Indexed: 11/17/2022] Open
Abstract
Protein-protein interactions (IPP) play an essential role in practically all biological processes, including those related to microorganism invasion of their host cells. It has been found that a broad repertoire of receptor-ligand interactions takes place in the binding interphase with host cells in malaria, these being vital interactions for successful parasite invasion. Several trials have been conducted for elucidating the molecular interface of interactions between some Plasmodium falciparum and Plasmodium vivax antigens with receptors on erythrocytes and/or reticulocytes. Structural information concerning these complexes is available; however, deeper analysis is required for correlating structural, functional (binding, invasion, and inhibition), and polymorphism data for elucidating new interaction hotspots to which malaria control methods can be directed. This review describes and discusses recent structural and functional details regarding three relevant interactions during erythrocyte invasion: Duffy-binding protein 1 (DBP1)–Duffy antigen receptor for chemokines (DARC); reticulocyte-binding protein homolog 5 (PfRh5)-basigin, and erythrocyte binding antigen 175 (EBA175)-glycophorin A (GPA).
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6
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Salamanca DR, Gómez M, Camargo A, Cuy-Chaparro L, Molina-Franky J, Reyes C, Patarroyo MA, Patarroyo ME. Plasmodium falciparum Blood Stage Antimalarial Vaccines: An Analysis of Ongoing Clinical Trials and New Perspectives Related to Synthetic Vaccines. Front Microbiol 2019; 10:2712. [PMID: 31849871 PMCID: PMC6901501 DOI: 10.3389/fmicb.2019.02712] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 11/08/2019] [Indexed: 01/10/2023] Open
Abstract
Plasmodium falciparum malaria is a disease causing high morbidity and mortality rates worldwide, mainly in sub-Saharan Africa. Candidates have been identified for vaccines targeting the parasite's blood stage; this stage is important in the development of symptoms and clinical complications. However, no vaccine that can directly affect morbidity and mortality rates is currently available. This review analyzes the formulation, methodological design, and results of active clinical trials for merozoite-stage vaccines, regarding their safety profile, immunological response (phase Ia/Ib), and protective efficacy levels (phase II). Most vaccine candidates are in phase I trials and have had an acceptable safety profile. GMZ2 has made the greatest progress in clinical trials; its efficacy has been 14% in children aged less than 5 years in a phase IIb trial. Most of the available candidates that have shown strong immunogenicity and that have been tested for their protective efficacy have provided good results when challenged with a homologous parasite strain; however, their efficacy has dropped when they have been exposed to a heterologous strain. In view of these vaccines' unpromising results, an alternative approach for selecting new candidates is needed; such line of work should be focused on how to increase an immune response induced against the highly conserved (i.e., common to all strains), functionally relevant, protein regions that the parasite uses to invade target cells. Despite binding regions tending to be conserved, they are usually poorly antigenic and/or immunogenic, being frequently discarded as vaccine candidates when the conventional immunological approach is followed. The Fundación Instituto de Inmunología de Colombia (FIDIC) has developed a logical and rational methodology based on including conserved high-activity binding peptides (cHABPs) from the main P. falciparum biologically functional proteins involved in red blood cell (RBC) invasion. Once appropriately modified (mHABPs), these minimal, subunit-based, chemically synthesized peptides can be used in a system covering the human immune system's main genetic variables (the human leukocyte antigen HLA-DR isotype) inducing a suitable, immunogenic, and protective immune response in most of the world's populations.
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Affiliation(s)
- David Ricardo Salamanca
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Ph.D. Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia.,Medicine Programme, Health Sciences Faculty, Universidad de Boyacá, Tunja, Colombia
| | - Marcela Gómez
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Ph.D. Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia.,Medicine Programme, Health Sciences Faculty, Universidad de Boyacá, Tunja, Colombia
| | - Anny Camargo
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Ph.D. Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia.,Medicine Programme, Health Sciences Faculty, Universidad de Boyacá, Tunja, Colombia
| | - Laura Cuy-Chaparro
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Ph.D. Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia.,Medicine Programme, Health Sciences Faculty, Universidad de Boyacá, Tunja, Colombia
| | - Jessica Molina-Franky
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Ph.D. Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia.,Medicine Programme, Health Sciences Faculty, Universidad de Boyacá, Tunja, Colombia
| | - César Reyes
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Ph.D. Programme in Biomedical and Biological Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Manuel Alfonso Patarroyo
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Basic Sciences Department, School of Medicine and Health Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Manuel Elkin Patarroyo
- Fundación Instituto de Inmunología de Colombia, Bogotá, Colombia.,Department of Pathology, School of Medicine, Universidad Nacional de Colombia, Boyacá, Colombia
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7
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Wamae KK, Ochola-Oyier LI. Implications from predicted B-cell and T-cell epitopes of Plasmodium falciparum merozoite proteins EBA175-RII and Rh5. Bioinformation 2016; 12:82-91. [PMID: 28149040 PMCID: PMC5267949 DOI: 10.6026/97320630012082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 03/21/2016] [Accepted: 03/25/2016] [Indexed: 11/23/2022] Open
Abstract
The leading circumsporozoite protein (CSP) based malaria vaccine, RTS,S, though promising, has shown limited efficacy in field studies. There is therefore, still a need to identify other malaria vaccine targets. Merozoite antigens are potential vaccine candidates, since naturally acquired antibodies generated against them inhibit erythrocyte invasion and in some cases result in the clinical protection from disease. We thus used in silico tools (BCPreds, NetMHCcons and NetMHCIIpan 3.0) to predict B-cell epitopes (BCEs) and T-cell epitopes (TCEs) in two merozoite invasion proteins, EBA175-RII and Rh5. Initially, we validated these tools using CSP to determine whether the algorithms could predict the epitopes in the RTS,S vaccine. In EBA175-RII, we prioritised three BCEs 15REKRKGMKWDCKKKNDRSNY34, 420SNRKLVGKINTNSNYVHRNKQ440 and 528WISKKKEEYNKQAKQYQEYQ547, a CD8+ epitope 553KMYSEFKSI561 and a CD4+ epitope 440QNDKLFRDEWWK VIKKD456. Three Rh5 epitopes were prioritised, a BCE 344SCYNNNFCNTNGIRYHYDEY363, a CD8+ epitope 198STYGKCIAV206 and a Rh5 CD4+ epitope 180TFLDYYKHLSYNSIYHKSSTY200. All these epitopes are in the region involved in the proteins' interaction with their erythrocyte receptors, thus enabling erythrocyte invasion. Therefore, upon validation of their immunogenicity, by ELISA using serum from a malaria endemic population, antibodies to these epitopes may inhibit erythrocyte invasion. All the epitopes we predicted in EBA175-RII and Rh5 are novel. We also identified polymorphic epitopes that may escape host immunity, as some variants were not predicted as epitopes, suggesting that they may not be immunogenic regions. We present a set of epitopes that following in vitro validation provide a set of molecules to screen as potential vaccine candidates.
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Affiliation(s)
- Kevin Kariuki Wamae
- Centre for Biotechnology and Bioinformatics, University of Nairobi, Kenya
- KEMRI-Wellcome Trust Collaborative Programme,Kilifi, Kenya; P.O. Box 230, Kilifi – 80108, Kenya
| | - Lynette Isabella Ochola-Oyier
- Centre for Biotechnology and Bioinformatics, University of Nairobi, Kenya
- KEMRI-Wellcome Trust Collaborative Programme,Kilifi, Kenya; P.O. Box 230, Kilifi – 80108, Kenya
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8
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Chiu CY, White MT, Healer J, Thompson JK, Siba PM, Mueller I, Cowman AF, Hansen DS. Different Regions of Plasmodium falciparum Erythrocyte-Binding Antigen 175 Induce Antibody Responses to Infection of Varied Efficacy. J Infect Dis 2016; 214:96-104. [PMID: 27020092 DOI: 10.1093/infdis/jiw119] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/18/2016] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Increasing evidence suggests that antibodies against merozoite proteins involved in Plasmodium falciparum invasion into the red blood cell play an important role in clinical immunity to malaria. Erythrocyte-binding antigen 175 (EBA-175) is the best-characterized P. falciparum invasion ligand, reported to recognize glycophorin A on the surface of erythrocytes. Its protein structure comprises 6 extracellular regions. Whereas region II contains Duffy binding-like domains involved in the binding to glycophorin A, the functional role of regions III-V is less clear. METHODS We developed a novel cytometric bead array for assessment of antigen-specific antibody concentration in plasma to evaluate the efficacy of immune responses to different regions of EBA-175 and associations between antibody levels with protection from symptomatic malaria in a treatment-reinfection cohort study. RESULTS We found that while antibodies to region II are highly abundant, circulating levels as low as 5-10 µg/mL of antibodies specific for region III or the highly conserved regions IV-V predict strong protection from clinical malaria. CONCLUSIONS These results lend support for the development of conserved regions of EBA-175 as components in a combination of a malaria vaccine.
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Affiliation(s)
- Chris Y Chiu
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Michael T White
- The Walter and Eliza Hall Institute of Medical Research MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, United Kingdom
| | - Julie Healer
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Jenny K Thompson
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Peter M Siba
- Vector Borne Disease Unit, Papua New Guinea Institute of Medical Research, Goroka, Eastern Highlands Province
| | - Ivo Mueller
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Diana S Hansen
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
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9
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Reddy SB, Anders RF, Cross N, Mueller I, Senn N, Stanisic DI, Siba PM, Wahlgren M, Kironde F, Beeson JG, Persson KEM. Differences in affinity of monoclonal and naturally acquired polyclonal antibodies against Plasmodium falciparum merozoite antigens. BMC Microbiol 2015; 15:133. [PMID: 26149471 PMCID: PMC4491891 DOI: 10.1186/s12866-015-0461-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 06/03/2015] [Indexed: 11/10/2022] Open
Abstract
Background Malaria is a major global cause of deaths and a vaccine is urgently needed. Results We have employed the P. falciparum merozoite antigens MSP2-3D7/FC27 and AMA1, used them in ELISA, and coupled them in different ways using surface plasmon resonance (SPR) and estimated affinity (measured as kd) of monoclonal as well as naturally-acquired polyclonal antibodies in human plasma. There were major differences in kd depending on how the antigens were immobilized and where the His-tag was placed. For AMA1 we could see correlations with invasion inhibition. Using different immobilizations of proteins in SPR, we could see only moderate correlations with levels of antibodies in ELISA, indicating that in ELISA the proteins were not uniformly bound and that antibodies with many specificities exist in natural immunisation. The correlations between ELISA and SPR were enhanced when only parasite positive samples were included, which may indicate that high affinity antibodies are difficult to maintain over long periods of time. We found higher kd values for MSP2 (indicating lower affinity) compared to AMA1, which might be partly explained by MSP2 being an intrinsically disordered protein, while AMA1 is globular. Conclusions For future vaccine studies and for understanding immunity, it is important to consider how to present proteins to the immune system to achieve highest antibody affinities. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0461-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sreenivasulu B Reddy
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Robin F Anders
- Department of Biochemistry, La Trobe University, Vic, 3086, Australia
| | - Nadia Cross
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia
| | - Ivo Mueller
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Papua New Guinea Institute of Medical Research, Goroka, 441, Papua New Guinea
| | - Nicolas Senn
- Papua New Guinea Institute of Medical Research, Goroka, 441, Papua New Guinea.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Danielle I Stanisic
- Papua New Guinea Institute of Medical Research, Goroka, 441, Papua New Guinea.,Institute for Glycomics, Griffith University, Queensland, Australia
| | - Peter M Siba
- Papua New Guinea Institute of Medical Research, Goroka, 441, Papua New Guinea
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Fred Kironde
- Department of Biochemistry, Makerere University, Kampala, Uganda.,Habib Medical School, IUIU, Kampala, Uganda
| | - James G Beeson
- The Macfarlane Burnet Institute for Medical Research and Public Health, Melbourne, Victoria, Australia.,The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Kristina E M Persson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 171 77, Stockholm, Sweden. .,Department of Laboratory Medicine, Lund University, 22185, Lund, Sweden.
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10
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Irani V, Ramsland PA, Guy AJ, Siba PM, Mueller I, Richards JS, Beeson JG. Acquisition of Functional Antibodies That Block the Binding of Erythrocyte-Binding Antigen 175 and Protection Against Plasmodium falciparum Malaria in Children. Clin Infect Dis 2015; 61:1244-52. [PMID: 26136391 DOI: 10.1093/cid/civ525] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 05/22/2015] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The targets and mechanisms of human immunity to malaria are poorly understood, which poses a major barrier to malaria vaccine development. Antibodies play a key role in human immunity and may act by inhibiting receptor-binding functions of key merozoite invasion ligands. Antibodies to the major invasion ligand and vaccine candidate, erythrocyte-binding antigen 175 (EBA-175), have been linked with protection, but how these antibodies function has not been established. METHODS We developed 2 new assays that quantify the ability of antibodies to inhibit binding of EBA-175 to its erythrocyte receptor, glycophorin A, using either native or recombinant EBA-175. Binding-inhibitory antibodies were evaluated in a longitudinal cohort study of Papua New Guinean children and related to risk of malaria, age, infection status, and markers of parasite exposure. RESULTS Binding-inhibition assays (BIAs) were reproducible, and the 2 assays had a high level of agreement. Inhibitory antibodies were common among children, acquired in association with markers of increasing parasite exposure, and high in those children with active infection. Inhibitory antibodies correlated with total immunoglobulin G levels to the EBA-175 binding domain (region II). Importantly, binding-inhibitory antibodies were significantly associated with protection from symptomatic malaria when measured using either BIA. CONCLUSIONS Findings suggest that naturally acquired binding-inhibitory antibodies are an important functional mechanism that contributes to protection against malaria and further supports the potential of EBA-175 as a vaccine candidate. Identifying vaccines and approaches that induce potent binding-inhibitory antibodies may be a valuable strategy in the development of highly efficacious malaria vaccines.
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Affiliation(s)
- Vashti Irani
- Centre for Biomedical Research, Burnet Institute, Melbourne Department of Medicine, University of Melbourne, Parkville Department of Immunology, Monash University, Melbourne
| | - Paul A Ramsland
- Centre for Biomedical Research, Burnet Institute, Melbourne Department of Immunology, Monash University, Melbourne Department of Surgery, Austin Health, University of Melbourne, Heidelberg, Victoria School of Biomedical Sciences, Curtin Health Innovation Research Institute-Biosciences, Curtin University, Perth, Western Australia, Australia
| | - Andrew J Guy
- Centre for Biomedical Research, Burnet Institute, Melbourne Department of Immunology, Monash University, Melbourne
| | - Peter M Siba
- Papua New Guinea Institute of Medical Research, Goroka
| | - Ivo Mueller
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia Barcelona Centre for International Health Research, Spain
| | - Jack S Richards
- Centre for Biomedical Research, Burnet Institute, Melbourne Department of Medicine, University of Melbourne, Parkville Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - James G Beeson
- Centre for Biomedical Research, Burnet Institute, Melbourne Department of Medicine, University of Melbourne, Parkville Department of Microbiology, Monash University, Clayton, Victoria, Australia
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11
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Chitnis CE, Mukherjee P, Mehta S, Yazdani SS, Dhawan S, Shakri AR, Bhardwaj R, Bharadwaj R, Gupta PK, Hans D, Mazumdar S, Singh B, Kumar S, Pandey G, Parulekar V, Imbault N, Shivyogi P, Godbole G, Mohan K, Leroy O, Singh K, Chauhan VS. Phase I Clinical Trial of a Recombinant Blood Stage Vaccine Candidate for Plasmodium falciparum Malaria Based on MSP1 and EBA175. PLoS One 2015; 10:e0117820. [PMID: 25927360 PMCID: PMC4415778 DOI: 10.1371/journal.pone.0117820] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 12/30/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND A phase I randomised, controlled, single blind, dose escalation trial was conducted to evaluate safety and immunogenicity of JAIVAC-1, a recombinant blood stage vaccine candidate against Plasmodium falciparum malaria, composed of a physical mixture of two recombinant proteins, PfMSP-1(19), the 19 kD conserved, C-terminal region of PfMSP-1 and PfF2 the receptor-binding F2 domain of EBA175. METHOD Healthy malaria naïve Indian male subjects aged 18-45 years were recruited from the volunteer database of study site. Fifteen subjects in each cohort, randomised in a ratio of 2:1 and meeting the protocol specific eligibility criteria, were vaccinated either with three doses (10 μg, 25 μg and 50 μg of each antigen) of JAIVAC-1 formulated with adjuvant Montanide ISA 720 or with standard dosage of Hepatitis B vaccine. Each subject received the assigned vaccine in the deltoid muscle of the upper arms on Day 0, Day 28 and Day 180. RESULTS JAIVAC-1 was well tolerated and no serious adverse event was observed. All JAIVAC-1 subjects sero-converted for PfF2 but elicited poor immune response to PfMSP-1(19). Dose-response relationship was observed between vaccine dose of PfF2 and antibody response. The antibodies against PfF2 were predominantly of IgG1 and IgG3 isotype. Sera from JAIVAC-1 subjects reacted with late schizonts in a punctate pattern in immunofluorescence assays. Purified IgG from JAIVAC-1 sera displayed significant growth inhibitory activity against Plasmodium falciparum CAMP strain. CONCLUSION Antigen PfF2 should be retained as a component of a recombinant malaria vaccine but PfMSP-1(19) construct needs to be optimised to improve its immunogenicity. TRIAL REGISTRATION Clinical Trial Registry, India CTRI/2010/091/000301.
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Affiliation(s)
- Chetan E Chitnis
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Paushali Mukherjee
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Shantanu Mehta
- Malaria Vaccine Development Program (MVDP), New Delhi, India
| | - Syed Shams Yazdani
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Shikha Dhawan
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Ahmad Rushdi Shakri
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | | | - Rukmini Bharadwaj
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Puneet Kumar Gupta
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Dhiraj Hans
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Suman Mazumdar
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Bijender Singh
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Sanjeev Kumar
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Gaurav Pandey
- Malaria Vaccine Development Program (MVDP), New Delhi, India
| | | | | | | | | | - Krishna Mohan
- Bharat Biotech International Ltd. (BBIL), Hyderabad, India
| | - Odile Leroy
- European Vaccine Initiative (EVI), Heidelberg, Germany
| | - Kavita Singh
- Malaria Vaccine Development Program (MVDP), New Delhi, India
| | - Virander S Chauhan
- International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
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12
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Ahmed Ismail H, Tijani MK, Langer C, Reiling L, White MT, Beeson JG, Wahlgren M, Nwuba R, Persson KEM. Subclass responses and their half-lives for antibodies against EBA175 and PfRh2 in naturally acquired immunity against Plasmodium falciparum malaria. Malar J 2014; 13:425. [PMID: 25373511 PMCID: PMC4232678 DOI: 10.1186/1475-2875-13-425] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 10/25/2014] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Plasmodium falciparum EBA175 and PfRh2 belong to two main families involved in parasite invasion, and both are potential vaccine candidates. Current knowledge is limited regarding which target antigens and subclasses of antibodies are actually important for protection, and how naturally acquired immunity is achieved. METHODS Repeated blood samples were collected from individuals in Nigeria over a period of almost one year. ELISA was used to analyse subclasses of IgG responses. RESULTS For both EBA175 (region III-V) and (a fragment of) PfRh2, the dominant antibody responses consisted of IgG1 and IgG3 followed by IgG2, while for PfRh2 there was also a relatively prominent response for IgG4. High levels of IgG1, IgG2 and IgG3 for EBA175 and total IgG for PfRh2 correlated significantly with a lower parasitaemia during the study period. Children with HbAS had higher levels of some subclasses compared to children with HbAA, while in adults the pattern was the opposite. The half-lives of IgG2 and IgG4 against EBA175 were clearly shorter than those for IgG1 and IgG3. CONCLUSION EBA175 and PfRh2 are potential targets for protective antibodies since both correlated with lower parasitaemia. The shorter half-lives for IgG2 and IgG4 might explain why these subclasses are often considered less important in protection against malaria. Triggering the right subclass responses could be of critical importance in a successful vaccine. Further studies are needed to evaluate the role of haemoglobin polymorphisms and their malaria protective effects in this process.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Kristina E M Persson
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Nobels väg 16, 17177 Stockholm, Sweden.
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13
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RH5-Basigin interaction plays a major role in the host tropism of Plasmodium falciparum. Proc Natl Acad Sci U S A 2013; 110:20735-40. [PMID: 24297912 DOI: 10.1073/pnas.1320771110] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum, the cause of almost all human malaria mortality, is a member of the Laverania subgenus which infects African great apes. Interestingly, Laverania parasites exhibit strict host specificity in their natural environment: P. reichenowi, P. billcollinsi, and P. gaboni infect only chimpanzees; P. praefalciparum, P. blacklocki, and P. adleri are restricted to gorillas, and P. falciparum is pandemic in humans. The molecular mechanism(s) responsible for these host restrictions are not understood, although the interaction between the parasite blood-stage invasion ligand EBA175 and the host erythrocyte receptor Glycophorin-A (GYPA) has been implicated previously. We reexamined the role of the EBA175-GYPA interaction in host tropism using recombinant proteins and biophysical assays and found that EBA175 orthologs from the chimpanzee-restricted parasites P. reichenowi and P. billcollinsi both bound to human GYPA with affinities similar to that of P. falciparum, suggesting that the EBA175-GYPA interaction is unlikely to be the sole determinant of Laverania host specificity. We next investigated the contribution of the recently discovered Reticulocyte-binding protein Homolog 5 (RH5)-Basigin (BSG) interaction in host-species selectivity and found that P. falciparum RH5 bound chimpanzee BSG with a significantly lower affinity than human BSG and did not bind gorilla BSG, mirroring the known host tropism of P. falciparum. Using site-directed mutagenesis, we identified residues in BSG that are responsible for the species specificity of PfRH5 binding. Consistent with the essential role of the PfRH5-BSG interaction in erythrocyte invasion, we conclude that species-specific differences in the BSG receptor provide a molecular explanation for the restriction of P. falciparum to its human host.
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14
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Healer J, Thompson JK, Riglar DT, Wilson DW, Chiu YH, Miura K, Chen L, Hodder AN, Long CA, Hansen DS, Baum J, Cowman AF. Vaccination with conserved regions of erythrocyte-binding antigens induces neutralizing antibodies against multiple strains of Plasmodium falciparum. PLoS One 2013; 8:e72504. [PMID: 24039774 PMCID: PMC3769340 DOI: 10.1371/journal.pone.0072504] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 07/10/2013] [Indexed: 02/07/2023] Open
Abstract
Background A highly effective vaccine against Plasmodium falciparum malaria should induce potent, strain transcending immunity that broadly protects against the diverse population of parasites circulating globally. We aimed to identify vaccine candidates that fulfill the criteria. Methods We have measured growth inhibitory activity of antibodies raised to a range of antigens to identify those that can efficiently block merozoite invasion for geographically diverse strains of P. falciparum. Results This has shown that the conserved Region III-V, of the P. falciparum erythrocyte-binding antigen (EBA)-175 was able to induce antibodies that potently inhibit merozoite invasion across diverse parasite strains, including those reliant on invasion pathways independent of EBA-175 function. Additionally, the conserved RIII-V domain of EBA-140 also induced antibodies with strong in vitro parasite growth inhibitory activity. Conclusion We identify an alternative, highly conserved region (RIV-V) of EBA-175, present in all EBA proteins, that is the target of potent, strain transcending neutralizing antibodies, that represents a strong candidate for development as a component in a malaria vaccine.
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Affiliation(s)
- Julie Healer
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
| | | | - David T. Riglar
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Danny W. Wilson
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
| | - Yu-H.C. Chiu
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, Maryland, United States of America
| | - Lin Chen
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
| | - Anthony N. Hodder
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Disease, National Institutes of Health, Rockville, Maryland, United States of America
| | - Diana S. Hansen
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Jake Baum
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Alan F. Cowman
- Walter & Eliza Hall Institute for Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
- * E-mail:
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15
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Persson KEM, Fowkes FJI, McCallum FJ, Gicheru N, Reiling L, Richards JS, Wilson DW, Lopaticki S, Cowman AF, Marsh K, Beeson JG. Erythrocyte-binding antigens of Plasmodium falciparum are targets of human inhibitory antibodies and function to evade naturally acquired immunity. THE JOURNAL OF IMMUNOLOGY 2013; 191:785-94. [PMID: 23776178 DOI: 10.4049/jimmunol.1300444] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Abs that inhibit Plasmodium falciparum invasion of erythrocytes form an important component of human immunity against malaria, but key target Ags are largely unknown. Phenotypic variation by P. falciparum mediates the evasion of inhibitory Abs, contributing to the capacity of P. falciparum to cause repeat and chronic infections. However, Ags involved in mediating immune evasion have not been defined, and studies of the function of human Abs are limited. In this study, we used novel approaches to determine the importance of P. falciparum erythrocyte-binding Ags (EBAs), which are important invasion ligands, as targets of human invasion-inhibitory Abs and define their role in contributing to immune evasion through variation in function. We evaluated the invasion-inhibitory activity of acquired Abs from malaria-exposed children and adults from Kenya, using P. falciparum with disruption of genes encoding EBA140, EBA175, and EBA181, either individually or combined as EBA140/EBA175 or EBA175/EBA181 double knockouts. Our findings provide important new evidence that variation in the expression and function of the EBAs plays an important role in evasion of acquired Abs and that a substantial amount of phenotypic diversity results from variation in expression of different EBAs that contributes to immune evasion by P. falciparum. All three EBAs were identified as important targets of naturally acquired inhibitory Abs demonstrated by differential inhibition of parental parasites greater than EBA knockout lines. This knowledge will help to advance malaria vaccine development and suggests that multiple invasion ligands need to be targeted to overcome the capacity of P. falciparum for immune evasion.
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Affiliation(s)
- Kristina E M Persson
- Karolinska Institutet, Microbiology, Tumor and Cell Biology, 17177 Stockholm, Sweden.
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16
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Richards JS, Arumugam TU, Reiling L, Healer J, Hodder AN, Fowkes FJI, Cross N, Langer C, Takeo S, Uboldi AD, Thompson JK, Gilson PR, Coppel RL, Siba PM, King CL, Torii M, Chitnis CE, Narum DL, Mueller I, Crabb BS, Cowman AF, Tsuboi T, Beeson JG. Identification and prioritization of merozoite antigens as targets of protective human immunity to Plasmodium falciparum malaria for vaccine and biomarker development. THE JOURNAL OF IMMUNOLOGY 2013; 191:795-809. [PMID: 23776179 DOI: 10.4049/jimmunol.1300778] [Citation(s) in RCA: 180] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The development of effective malaria vaccines and immune biomarkers of malaria is a high priority for malaria control and elimination. Ags expressed by merozoites of Plasmodium falciparum are likely to be important targets of human immunity and are promising vaccine candidates, but very few Ags have been studied. We developed an approach to assess Ab responses to a comprehensive repertoire of merozoite proteins and investigate whether they are targets of protective Abs. We expressed 91 recombinant proteins, located on the merozoite surface or within invasion organelles, and screened them for quality and reactivity to human Abs. Subsequently, Abs to 46 proteins were studied in a longitudinal cohort of 206 Papua New Guinean children to define Ab acquisition and associations with protective immunity. Ab responses were higher among older children and those with active parasitemia. High-level Ab responses to rhoptry and microneme proteins that function in erythrocyte invasion were identified as being most strongly associated with protective immunity compared with other Ags. Additionally, Abs to new or understudied Ags were more strongly associated with protection than were Abs to current vaccine candidates that have progressed to phase 1 or 2 vaccine trials. Combinations of Ab responses were identified that were more strongly associated with protective immunity than responses to their single-Ag components. This study identifies Ags that are likely to be key targets of protective human immunity and facilitates the prioritization of Ags for further evaluation as vaccine candidates and/or for use as biomarkers of immunity in malaria surveillance and control.
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Affiliation(s)
- Jack S Richards
- Department of Immunology, Burnet Institute, Melbourne 3001, Victoria, Australia
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17
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Kwon KC, Verma D, Singh ND, Herzog R, Daniell H. Oral delivery of human biopharmaceuticals, autoantigens and vaccine antigens bioencapsulated in plant cells. Adv Drug Deliv Rev 2013; 65:782-99. [PMID: 23099275 PMCID: PMC3582797 DOI: 10.1016/j.addr.2012.10.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 09/26/2012] [Accepted: 10/17/2012] [Indexed: 12/19/2022]
Abstract
Among 12billion injections administered annually, unsafe delivery leads to >20million infections and >100million reactions. In an emerging new concept, freeze-dried plant cells (lettuce) expressing vaccine antigens/biopharmaceuticals are protected in the stomach from acids/enzymes but are released to the immune or blood circulatory system when plant cell walls are digested by microbes that colonize the gut. Vaccine antigens bioencapsulated in plant cells upon oral delivery after priming, conferred both mucosal and systemic immunity and protection against bacterial, viral or protozoan pathogens or toxin challenge. Oral delivery of autoantigens was effective against complications of type 1 diabetes and hemophilia, by developing tolerance. Oral delivery of proinsulin or exendin-4 expressed in plant cells regulated blood glucose levels similar to injections. Therefore, this new platform offers a low cost alternative to deliver different therapeutic proteins to combat infectious or inherited diseases by eliminating inactivated pathogens, expensive purification, cold storage/transportation and sterile injections.
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Affiliation(s)
- Kwang-Chul Kwon
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Biomolecular Science Building, Orlando, FL 32816-2364, USA
| | - Dheeraj Verma
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Biomolecular Science Building, Orlando, FL 32816-2364, USA
| | - Nameirakpam D. Singh
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Biomolecular Science Building, Orlando, FL 32816-2364, USA
| | - Roland Herzog
- Department of Pediatrics, College of Medicine, University of Florida, Cancer and Genetics Research Complex, 2033 Mowry Road, Gainesville, FL 32610, USA
| | - Henry Daniell
- Department of Molecular Biology and Microbiology, College of Medicine, University of Central Florida, Biomolecular Science Building, Orlando, FL 32816-2364, USA
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18
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Inhibitory humoral responses to the Plasmodium falciparum vaccine candidate EBA-175 are independent of the erythrocyte invasion pathway. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:1238-45. [PMID: 23761656 DOI: 10.1128/cvi.00135-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Plasmodium falciparum utilizes multiple ligand-receptor interactions for invasion. The invasion ligand EBA-175 is being developed as a major blood-stage vaccine candidate. EBA-175 mediates parasite invasion of host erythrocytes in a sialic acid-dependent manner through its binding to the erythrocyte receptor glycophorin A. In this study, we addressed the ability of naturally acquired human antibodies against the EBA-175 RII erythrocyte-binding domain to inhibit parasite invasion of ex vivo isolates, in relationship to the sialic acid dependence of these parasites. We have determined the presence of antibodies to the EBA-175 RII domain by enzyme-linked immunosorbent assay (ELISA) in individuals from areas of Senegal where malaria is endemic with high and low transmission. Using affinity-purified human antibodies to the EBA-175 RII domain from pooled patient plasma, we have measured the invasion pathway as well as the invasion inhibition of clinical isolates from Senegalese patients in ex vivo assays. Our results suggest that naturally acquired anti-EBA-175 RII antibodies significantly inhibit invasion of Senegalese parasites and that these responses can be significantly enhanced through limiting other ligand-receptor interactions. However, the extent of this functional inhibition by EBA-175 antibodies is not associated with the sialic acid dependence of the parasite strain, suggesting that erythrocyte invasion pathway usage by parasite strains is not driven by antibodies targeting the EBA-175/glycophorin A interaction. This work has implications for vaccine design based on the RII domain of EBA-175 in the context of alternative invasion pathways.
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19
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Ambroggio X, Jiang L, Aebig J, Obiakor H, Lukszo J, Narum DL. The epitope of monoclonal antibodies blocking erythrocyte invasion by Plasmodium falciparum map to the dimerization and receptor glycan binding sites of EBA-175. PLoS One 2013; 8:e56326. [PMID: 23457550 PMCID: PMC3574135 DOI: 10.1371/journal.pone.0056326] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 01/08/2013] [Indexed: 01/08/2023] Open
Abstract
The malaria parasite, Plasmodium falciparum, and related parasites use a variety of proteins with Duffy-Binding Like (DBL) domains to bind glycoproteins on the surface of host cells. Among these proteins, the 175 kDa erythrocyte binding antigen, EBA-175, specifically binds to glycophorin A on the surface of human erythrocytes during the process of merozoite invasion. The domain responsible for glycophorin A binding was identified as region II (RII) which contains two DBL domains, F1 and F2. The crystal structure of this region revealed a dimer that is presumed to represent the glycophorin A binding conformation as sialic acid binding sites and large cavities are observed at the dimer interface. The dimer interface is largely composed of two loops from within each monomer, identified as the F1 and F2 β-fingers that contact depressions in the opposing monomers in a similar manner. Previous studies have identified a panel of five monoclonal antibodies (mAbs) termed R215 to R218 and R256 that bind to RII and inhibit invasion of erythrocytes to varying extents. In this study, we predict the F2 β-finger region as the conformational epitope for mAbs, R215, R217, and R256, and confirm binding for the most effective blocking mAb R217 and R215 to a synthetic peptide mimic of the F2 β-finger. Localization of the epitope to the dimerization and glycan binding sites of EBA-175 RII and site-directed mutagenesis within the predicted epitope are consistent with R215 and R217 blocking erythrocyte invasion by Plasmodium falciparum by preventing formation of the EBA-175– glycophorin A complex.
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Affiliation(s)
- Xavier Ambroggio
- Bioinformatics and Computational Biosciences Branch, Office of Cyber Infrastructure and Computational Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lubin Jiang
- Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai, China
| | - Joan Aebig
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Harold Obiakor
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Jan Lukszo
- Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - David L. Narum
- 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:
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20
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Williams AR, Douglas AD, Miura K, Illingworth JJ, Choudhary P, Murungi LM, Furze JM, Diouf A, Miotto O, Crosnier C, Wright GJ, Kwiatkowski DP, Fairhurst RM, Long CA, Draper SJ. Enhancing blockade of Plasmodium falciparum erythrocyte invasion: assessing combinations of antibodies against PfRH5 and other merozoite antigens. PLoS Pathog 2012; 8:e1002991. [PMID: 23144611 PMCID: PMC3493472 DOI: 10.1371/journal.ppat.1002991] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 09/11/2012] [Indexed: 02/01/2023] Open
Abstract
No vaccine has yet proven effective against the blood-stages of Plasmodium falciparum, which cause the symptoms and severe manifestations of malaria. We recently found that PfRH5, a P. falciparum-specific protein expressed in merozoites, is efficiently targeted by broadly-neutralizing, vaccine-induced antibodies. Here we show that antibodies against PfRH5 efficiently inhibit the in vitro growth of short-term-adapted parasite isolates from Cambodia, and that the EC50 values of antigen-specific antibodies against PfRH5 are lower than those against PfAMA1. Since antibody responses elicited by multiple antigens are speculated to improve the efficacy of blood-stage vaccines, we conducted detailed assessments of parasite growth inhibition by antibodies against PfRH5 in combination with antibodies against seven other merozoite antigens. We found that antibodies against PfRH5 act synergistically with antibodies against certain other merozoite antigens, most notably with antibodies against other erythrocyte-binding antigens such as PfRH4, to inhibit the growth of a homologous P. falciparum clone. A combination of antibodies against PfRH4 and basigin, the erythrocyte receptor for PfRH5, also potently inhibited parasite growth. This methodology provides the first quantitative evidence that polyclonal vaccine-induced antibodies can act synergistically against P. falciparum antigens and should help to guide the rational development of future multi-antigen vaccines. Malaria is the most devastating parasitic disease of humans, resulting in an estimated 0.6–1 million deaths per year. The symptoms of malaria are caused when merozoites invade and replicate within red blood cells, and therefore a vaccine which induced antibodies that effectively prevent this invasion process would be a major step towards the control of the disease. However, development of such a vaccine has proved extremely challenging. A major roadblock has been the probable need for extremely high levels of antibodies to achieve vaccine efficacy. We have now shown that antibodies against the merozoite protein PfRH5 are able to neutralize the invasion of red blood cells by malaria parasites at concentrations that are significantly lower than for antibodies against PfAMA1 – the previous leading blood-stage malaria vaccine target. This neutralization was observed in both laboratory-adapted parasite lines and in five different parasite isolates from Cambodian patients with malaria. Furthermore, we found that by combining antibodies against PfRH5 with antibodies against certain other merozoite antigens we could achieve synergistic neutralization of parasites, further lowering the amount of antibody needed to be induced by a vaccine. The development of vaccines encoding the PfRH5 antigen in combination with a second target may thus be the best way to achieve the long-sought after goal of an efficacious blood-stage malaria vaccine. Moreover, the methodology described here to assess the ability of antibodies against different targets to synergize should greatly aid the future rational design of improved vaccine candidates.
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Plasmodium falciparum line-dependent association of in vitro growth-inhibitory activity and risk of malaria. Infect Immun 2012; 80:1900-8. [PMID: 22392930 DOI: 10.1128/iai.06190-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum's ability to invade erythrocytes is essential for its survival within the human host. Immune mechanisms that impair this ability are therefore expected to contribute to immunity against the parasite. Plasma of humans who are naturally exposed to malaria has been shown to have growth-inhibitory activity (GIA) in vitro. However, the importance of GIA in relation to protection from malaria has been unclear. In a case-control study nested within a longitudinally followed population in Tanzania, plasma samples collected at baseline from 171 individuals (55 cases and 116 age-matched controls) were assayed for GIA using three P. falciparum lines (3D7, K1, and W2mef) chosen based on their erythrocyte invasion phenotypes. Distribution of GIA differed between the lines, with most samples inhibiting the growth of 3D7 and K1 and enhancing the growth of W2mef. GIA to 3D7 was associated with a reduced risk of malaria within 40 weeks of follow-up (odds ratio, 0.45; 95% confidence interval [CI], 0.21 to 0.96; P = 0.04), whereas GIA to K1 and W2mef was not. These results show that GIA, as well as its association with protection from malaria, is dependent on the P. falciparum line and can be explained by differences in erythrocyte invasion phenotypes between parasite lines. Our study contributes knowledge on the biological importance of growth inhibition and the potential influence of P. falciparum erythrocyte invasion phenotypic differences on its relationship to protective immunity against malaria.
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Ord RL, Rodriguez M, Yamasaki T, Takeo S, Tsuboi T, Lobo CA. Targeting sialic acid dependent and independent pathways of invasion in Plasmodium falciparum. PLoS One 2012; 7:e30251. [PMID: 22253925 PMCID: PMC3257272 DOI: 10.1371/journal.pone.0030251] [Citation(s) in RCA: 30] [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: 10/03/2011] [Accepted: 12/16/2011] [Indexed: 02/04/2023] Open
Abstract
The pathology of malaria is a consequence of the parasitaemia which develops through the cyclical asexual replication of parasites in a patient's red blood cells. Multiple parasite ligand-erythrocyte receptor interactions must occur for successful Plasmodium invasion of the human red cell. Two major malaria ligand families have been implicated in these variable ligand-receptor interactions used by Plasmodium falciparum to invade human red cells: the micronemal proteins from the Erythrocyte Binding Ligands (EBL) family and the rhoptry proteins from the Reticulocyte binding Homolog (PfRH) family. Ligands from the EBL family largely govern the sialic acid (SA) dependent pathways of invasion and the RH family ligands (except for RH1) mediate SA independent invasion. In an attempt to dissect out the invasion inhibitory effects of antibodies against ligands from both pathways, we have used EBA-175 and RH5 as model members of each pathway. Mice were immunized with either region II of EBA-175 produced in Pichia pastoris or full-length RH5 produced by the wheat germ cell-free system, or a combination of the two antigens to look for synergistic inhibitory effects of the induced antibodies. Sera obtained from these immunizations were tested for native antigen recognition and for efficacy in invasion inhibition assays. Results obtained show promise for the potential use of such hybrid vaccines to induce antibodies that can block multiple parasite ligand-red cell receptor interactions and thus inhibit parasite invasion.
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Affiliation(s)
- Rosalynn Louise Ord
- Department of Blood-Borne Parasites, New York Blood Center, New York, New York, United States of America
| | - Marilis Rodriguez
- Department of Blood-Borne Parasites, New York Blood Center, New York, New York, United States of America
| | - Tsutomu Yamasaki
- Cell-Free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
| | - Satoru Takeo
- Cell-Free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
| | - Takafumi Tsuboi
- Cell-Free Science and Technology Research Center, Ehime University, Matsuyama, Ehime, Japan
- Venture Business Laboratory, Ehime University, Matsuyama, Ehime, Japan
- Ehime Proteo-Medicine Research Center, Ehime University, Toon, Ehime, Japan
| | - Cheryl A. Lobo
- Department of Blood-Borne Parasites, New York Blood Center, New York, New York, United States of America
- * E-mail:
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Antibodies to Plasmodium falciparum erythrocyte-binding antigen-175 are associated with protection from clinical malaria. Pediatr Infect Dis J 2011; 30:1037-42. [PMID: 21817955 PMCID: PMC3222715 DOI: 10.1097/inf.0b013e31822d1451] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Antibodies to blood-stage Plasmodium falciparum antigens have been associated with protection against clinical malaria in some studies but not others. Many of these studies have not assessed whether high-titer antibodies are associated with protection and have not adjusted for differences in malaria exposure. METHODS The presence of high-titer antibodies to apical membrane antigen-1, erythrocyte-binding antigen-175 (EBA-175), and merozoite surface protein-1₁₉ (MSP-1₁₉) was assessed in 87 children living in a malaria holoendemic area of Kenya. The children were prospectively assessed during 1 year for clinical malaria. RESULTS In unadjusted analyses, high-titer antibodies to MSP-1₁₉, but not EBA-175 or apical membrane antigen-1, were associated with protection from clinical malaria. However, after adjustment for exposure, only high-titer antibodies to EBA-175 were associated with protection from clinical malaria (hazard ratio, 0.48; 95% confidence interval [CI], 0.24, 0.95; P = 0.03), and with reduced episodes of clinical malaria (incidence rate ratio, 0.50; 95% CI, 0.31, 0.81; P = 0.005). A trend toward increased protection from clinical malaria in children was seen with antibodies to both EBA-175 and MSP-1₁₉ (hazard ratio, 0.26; 95% CI, 0.03, 1.94; P = 0.18). CONCLUSIONS High-titer antibodies to EBA-175 are associated with protection from clinical malaria in children in a malaria holoendemic area of Kenya. Accurate estimates of antibody-associated protection from clinical malaria require adjustment for malaria exposure.
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Abstract
Currently, there are no reliable RBC invasion assays to guide the discovery of vaccines against Plasmodium vivax, the most prevalent malaria parasite in Asia and South America. Here we describe a protocol for an ex vivo P vivax invasion assay that can be easily deployed in laboratories located in endemic countries. The assay is based on mixing enriched cord blood reticulocytes with matured, trypsin-treated P vivax schizonts concentrated from clinical isolates. The reliability of this assay was demonstrated using a large panel of P vivax isolates freshly collected from patients in Thailand.
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Evidence for erythrocyte-binding antigen 175 as a component of a ligand-blocking blood-stage malaria vaccine. Proc Natl Acad Sci U S A 2011; 108:7553-8. [PMID: 21502513 DOI: 10.1073/pnas.1104050108] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The ligands that pathogens use to invade their target cells have often proven to be good targets for vaccine development. However, Plasmodium falciparum has redundant ligands that mediate invasion of erythrocytes. The first requirement for the development of a successful ligand-blocking malaria vaccine is the demonstration that antibodies induced to each ligand can block the erythrocyte invasion of parasites with polymorphic sequences. Because of P. falciparum's redundancy in erythrocyte invasion, each ligand needs to be studied under artificial conditions in which parasite invasion is restricted in its use of alternative pathways. Here we investigate the role of erythrocyte-binding antigen 175 (EBA-175), a parasite ligand that binds to sialic acid on glycophorin A, in the invasion of erythrocytes by 10 P. falciparum clones under conditions in which invasion is partially limited to the EBA-175-glycophorin A pathway, using chymotrypsin-treated erythrocytes. We show that the ability to invade erythrocytes for both sialic acid-independent and sialic acid-dependent pathways requires the EBA-175-glycophorin A pathway for erythrocyte invasion. Importantly, antibodies against region II of EBA-175 from the 3D7 clone blocked invasion of chymotrypsin-treated erythrocytes by >50% by all parasite clones studied, including those with multiple different mutations described in the literature. The one exception was FCR3, which had a similar sequence to 3D7 but only 30% inhibition of invasion of chymotrypsin-treated erythrocytes, indicating alternative pathways for invasion of chymotrypsin-treated erythrocytes. Our findings suggest that antibodies to region II of EBA-175, as one component of a ligand-blocking malaria vaccine, are largely unaffected by polymorphism in EBA-175.
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Sim BKL, Narum DL, Chattopadhyay R, Ahumada A, Haynes JD, Fuhrmann SR, Wingard JN, Liang H, Moch JK, Hoffman SL. Delineation of stage specific expression of Plasmodium falciparum EBA-175 by biologically functional region II monoclonal antibodies. PLoS One 2011; 6:e18393. [PMID: 21533224 PMCID: PMC3077373 DOI: 10.1371/journal.pone.0018393] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 02/28/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The malaria parasite Plasmodium falciparum EBA-175 binds its receptor sialic acids on glycophorin A when invading erythrocytes. The receptor-binding region (RII) contains two cysteine-rich domains with similar cysteine motifs (F1 and F2). Functional relationships between F1 and F2 domains and characterization of EBA-175 were studied using specific monoclonal antibodies (mAbs) against these domains. METHODS AND FINDINGS Five mAbs specific for F1 or F2 were generated. Three mAbs specific for F2 potently blocked binding of EBA-175 to erythrocytes, and merozoite invasion of erythrocytes (IC(50) 10 to 100 µg/ml IgG in growth inhibition assays). A mAb specific for F1 blocked EBA-175 binding and merozoite invasion less effectively. The difference observed between the IC(50) of F1 and F2 mAbs was not due to differing association and disassociation rates as determined by surface plasmon resonance. Four of the mAbs recognized conformation-dependent epitopes within F1 or F2. Used in combination, F1 and F2 mAbs blocked the binding of native EBA-175 to erythrocytes and inhibited parasite invasion synergistically in vitro. MAb R217, the most potent, did not recognize sporozoites, 3-day hepatocyte stage parasites, nor rings, trophozoites, gametocytes, retorts, ookinetes, and oocysts but recognized 6-day hepatocyte stage parasites, and schizonts. Even though efficient at blocking binding to erythrocytes and inhibiting invasion into erythrocytes, MAb R217 did not inhibit sporozoite invasion and development in hepatocytes in vitro. CONCLUSIONS The role of the F1 and F2 domains in erythrocyte invasion and binding was elucidated with mAbs. These mAbs interfere with native EBA-175 binding to erythrocyte in a synergistic fashion. The stage specific expression of EBA-175 showed that the primary focus of activity was the merozoite stage. A recombinant RII protein vaccine consisting of both F1 and F2 domains that could induce synergistic activity should be optimal for induction of antibody responses that interfere with merozoite invasion of erythrocytes.
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Affiliation(s)
- B Kim Lee Sim
- Protein Potential LLC, Rockville, Maryland, United States of America.
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Abstract
Vaccines could be a crucial component of efforts to eradicate malaria. Current attempts to develop malaria vaccines are primarily focused on Plasmodium falciparum and are directed towards reducing morbidity and mortality. Continued support for these efforts is essential, but if malaria vaccines are to be used as part of a repertoire of tools for elimination or eradication of malaria, they will need to have an impact on malaria transmission. We introduce the concept of "vaccines that interrupt malaria transmission" (VIMT), which includes not only "classical" transmission-blocking vaccines that target the sexual and mosquito stages but also pre-erythrocytic and asexual stage vaccines that have an effect on transmission. VIMT may also include vaccines that target the vector to disrupt parasite development in the mosquito. Importantly, if eradication is to be achieved, malaria vaccine development efforts will need to target other malaria parasite species, especially Plasmodium vivax, where novel therapeutic vaccines against hypnozoites or preventive vaccines with effect against multiple stages could have enormous impact. A target product profile (TPP) for VIMT is proposed and a research agenda to address current knowledge gaps and develop tools necessary for design and development of VIMT is presented.
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Safety and immunogenicity of a recombinant nonglycosylated erythrocyte binding antigen 175 Region II malaria vaccine in healthy adults living in an area where malaria is not endemic. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2010; 17:1552-9. [PMID: 20702657 DOI: 10.1128/cvi.00082-10] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Erythrocyte binding antigen region II (EBA-175) is a conserved antigen of Plasmodium falciparum that is involved in binding of the parasite to the host's erythrocytes. We evaluated the safety and immunogenicity of a recombinant EBA-175 vaccine with aluminum phosphate adjuvant in healthy young adults living in the United States. Eighteen subjects/group received ascending doses (5, 20, 80, or 160 μg) of the vaccine at 0, 1, and 6 months; 8 subjects received placebo. Most of the injection site and systemic reactions were mild to moderate in intensity. After 2 or 3 doses of the vaccine at any concentration, antibody levels measured by enzyme-linked immunosorbent assay were significantly higher than those for the placebo group. Sera from subjects who received 3 doses of the vaccine at any concentration inhibited the growth of erythrocyte-stage P. falciparum at low levels compared to sera from placebo recipients or preimmune sera. In conclusion, the EBA-175 vaccine with adjuvant was safe and immunogenic in malaria-naïve subjects.
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Brown A, Higgins MK. Carbohydrate binding molecules in malaria pathology. Curr Opin Struct Biol 2010; 20:560-6. [PMID: 20655195 DOI: 10.1016/j.sbi.2010.06.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 06/07/2010] [Accepted: 06/25/2010] [Indexed: 11/27/2022]
Abstract
Interactions between parasite-encoded proteins and host carbohydrate molecules are essential at multiple stages in the life cycle of the malaria-causing parasite, Plasmodium falciparum, and these interactions are targets for the development of therapeutics to treat the disease. Here we review recent structural studies of carbohydrate binding modules that mediate recognition events important for cell invasion and cytoadhesion. In particular we focus on the structures of two molecules; the erythrocyte binding antigen, EBA-175 involved in erythrocyte invasion and the VAR2CSA protein that mediates binding of infected erythrocytes to the placenta. These proteins both use Duffy-binding like (DBL) domains, a Plasmodium specific fold, to bind host carbohydrates, but recent results show that they differ significantly in their architectures and modes of ligand recognition.
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Affiliation(s)
- Alan Brown
- Department of Biochemistry, University of Cambridge, 80, Tennis Court Road, Cambridge, CB2 1GA, United Kingdom.
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Wilson DW, Crabb BS, Beeson JG. Development of fluorescent Plasmodium falciparum for in vitro growth inhibition assays. Malar J 2010; 9:152. [PMID: 20525251 PMCID: PMC2891815 DOI: 10.1186/1475-2875-9-152] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 06/03/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum in vitro growth inhibition assays are widely used to evaluate and quantify the functional activity of acquired and vaccine-induced antibodies and the anti-malarial activity of known drugs and novel compounds. However, several constraints have limited the use of these assays in large-scale population studies, vaccine trials and compound screening for drug discovery and development. METHODS The D10 P. falciparum line was transfected to express green fluorescent protein (GFP). In vitro growth inhibition assays were performed over one or two cycles of P. falciparum asexual replication using inhibitory polyclonal antibodies raised in rabbits, an inhibitory monoclonal antibody, human serum samples, and anti-malarials. Parasitaemia was evaluated by microscopy and flow cytometry. RESULTS Transfected parasites expressed GFP throughout all asexual stages and were clearly detectable by flow cytometry and fluorescence microscopy. Measurement of parasite growth inhibition was the same when determined by detection of GFP fluorescence or staining with ethidium bromide. There was no difference in the inhibitory activity of samples when tested against the transfected parasites compared to the parental line. The level of fluorescence of GFP-expressing parasites increased throughout the course of asexual development. Among ring-stages, GFP-fluorescent parasites were readily separated from uninfected erythrocytes by flow cytometry, whereas this was less clear using ethidium bromide staining. Inhibition by serum and antibody samples was consistently higher when tested over two cycles of growth compared to one, and when using a 1 in 10 sample dilution compared to 1 in 20, but there was no difference detected when using a different starting parasitaemia to set-up growth assays. Flow cytometry based measurements of parasitaemia proved more reproducible than microscopy counts. CONCLUSIONS Flow cytometry based assays using GFP-fluorescent parasites proved sensitive and highly reproducible for quantifying the growth-inhibitory activity of antibodies and anti-malarials, with superior reproducibility to light microscopy, and are suitable for high-throughput applications.
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Affiliation(s)
- Danny W Wilson
- Infection and Immunity Division, the Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3050, Australia
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Antibodies to reticulocyte binding protein-like homologue 4 inhibit invasion of Plasmodium falciparum into human erythrocytes. Infect Immun 2009; 77:2427-35. [PMID: 19307208 DOI: 10.1128/iai.00048-09] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Plasmodium falciparum invasion into human erythrocytes relies on the interaction between multiple parasite ligands and their respective erythrocyte receptors. The sialic acid-independent invasion pathway is dependent on the expression of P. falciparum reticulocyte binding protein-like homologue 4 (PfRh4), as disruption of the gene abolishes the ability of parasites to switch to this pathway. We show that PfRh4 is present as an invasion ligand in culture supernatants as a 160-kDa proteolytic fragment. We confirm that PfRh4 binds to the surfaces of erythrocytes through recognition of an erythrocyte receptor that is neuraminidase resistant but trypsin and chymotrypsin sensitive. Serum antibodies from malaria-exposed individuals show reactivity against the binding domain of PfRh4. Purified immunoglobulin G raised in rabbits against the binding domain of PfRh4 blocked the binding of native PfRh4 to the surfaces of erythrocytes and inhibited erythrocyte invasion of parasites using sialic acid-independent invasion pathways and grown in neuraminidase-treated erythrocytes. Our results suggest PfRh4 is a potential vaccine candidate.
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Erythrocyte invasion by Plasmodium falciparum: multiple ligand-receptor interactions and phenotypic switching. Subcell Biochem 2008; 47:46-57. [PMID: 18512340 DOI: 10.1007/978-0-387-78267-6_3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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McCallum FJ, Persson KEM, Mugyenyi CK, Fowkes FJI, Simpson JA, Richards JS, Williams TN, Marsh K, Beeson JG. Acquisition of growth-inhibitory antibodies against blood-stage Plasmodium falciparum. PLoS One 2008; 3:e3571. [PMID: 18958278 PMCID: PMC2570221 DOI: 10.1371/journal.pone.0003571] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2008] [Accepted: 10/07/2008] [Indexed: 11/18/2022] Open
Abstract
Background Antibodies that inhibit the growth of blood-stage Plasmodium falciparum may play an important role in acquired and vaccine-induced immunity in humans. However, the acquisition and activity of these antibodies is not well understood. Methods We tested dialysed serum and purified immunoglobulins from Kenyan children and adults for inhibition of P. falciparum blood-stage growth in vitro using different parasite lines. Serum antibodies were measured by ELISA to blood-stage parasite antigens, extracted from P. falciparum schizonts, and to recombinant merozoite surface protein 1 (42 kDa C-terminal fragment, MSP1-42). Results Antibodies to blood-stage antigens present in schizont protein extract and to recombinant MSP1-42 significantly increased with age and were highly correlated. In contrast, growth-inhibitory activity was not strongly associated with age and tended to decline marginally with increasing age and exposure, with young children demonstrating the highest inhibitory activity. Comparison of growth-inhibitory activity among samples collected from the same population at different time points suggested that malaria transmission intensity influenced the level of growth-inhibitory antibodies. Antibodies to recombinant MSP1-42 were not associated with growth inhibition and high immunoglobulin G levels were poorly predictive of inhibitory activity. The level of inhibitory activity against different isolates varied. Conclusions Children can acquire growth-inhibitory antibodies at a young age, but once they are acquired they do not appear to be boosted by on-going exposure. Inhibitory antibodies may play a role in protection from early childhood malaria.
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Affiliation(s)
- Fiona J. McCallum
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | | | - Cleopatra K. Mugyenyi
- Kenya Medical Research Institute, CGMRC/Wellcome Trust Collaborative Program, Kilifi, Kenya
| | - Freya J. I. Fowkes
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Julie A. Simpson
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne, Carlton, Victoria, Australia
| | - Jack S. Richards
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Thomas N. Williams
- Kenya Medical Research Institute, CGMRC/Wellcome Trust Collaborative Program, Kilifi, Kenya
| | - Kevin Marsh
- Kenya Medical Research Institute, CGMRC/Wellcome Trust Collaborative Program, Kilifi, Kenya
| | - James G. Beeson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- * E-mail:
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Rodriguez LE, Curtidor H, Urquiza M, Cifuentes G, Reyes C, Patarroyo ME. Intimate Molecular Interactions of P. falciparum Merozoite Proteins Involved in Invasion of Red Blood Cells and Their Implications for Vaccine Design. Chem Rev 2008; 108:3656-705. [DOI: 10.1021/cr068407v] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Hernando Curtidor
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia
| | - Mauricio Urquiza
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia
| | - Gladys Cifuentes
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia
| | - Claudia Reyes
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia
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Moreno A, Caro-Aguilar I, Yazdani SS, Shakri AR, Lapp S, Strobert E, McClure H, Chitnis CE, Galinski MR. Preclinical assessment of the receptor-binding domain of Plasmodium vivax Duffy-binding protein as a vaccine candidate in rhesus macaques. Vaccine 2008; 26:4338-44. [PMID: 18573299 DOI: 10.1016/j.vaccine.2008.06.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Revised: 05/29/2008] [Accepted: 06/04/2008] [Indexed: 11/17/2022]
Abstract
The receptor-binding domain of Plasmodium vivax Duffy-binding protein, region II (PvRII), is an attractive candidate for a vaccine against P. vivax malaria. Here, we have studied the safety and immunogenicity of recombinant PvRII in Macaca mulatta (rhesus monkeys). Recombinant PvRII with a C-terminal 6-histidine tag was expressed in E. coli, recovered from inclusion bodies, refolded into its functional conformation, purified to homogeneity and formulated with three adjuvants, namely, Alhydrogel, Montanide ISA 720 and the GSK proprietary Adjuvant System AS02A for use in immunogenicity studies. All the PvRII vaccine formulations tested were safe and highly immunogenic. The overall magnitude of the antibody response was significantly higher for both Montanide ISA 720 and AS02A formulations in comparison with Alhydrogel. Furthermore, there was a significant correlation between antibody recognition titers by ELISA and binding inhibition titers in in vitro binding assays. The PvRII vaccine formulations also induced IFN-gamma recall responses that were identified using ex vivo ELISPOT assays. These results provide support for further clinical development of a vaccine for P. vivax malaria based on recombinant PvRII.
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Affiliation(s)
- A Moreno
- Emory Vaccine Center & Yerkes National Primate Research Center, Emory University, 954 Gatewood Road, Atlanta, GA 30329, USA.
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Abstract
Microneme secretion supports several key cellular processes including gliding motility, active cell invasion and migration through cells, biological barriers, and tissues. The modular design of microneme proteins enables these molecules to assist each other in folding and passage through the quality control system, accurately target to the micronemes, oligimerizing with other parasite proteins, and engaging a variety of host receptors for migration and cell invasion. Structural and biochemical analyses of MIC domains is providing new perspectives on how adhesion is regulated and the potentially distinct roles MICs might play in long or short range interactions during parasite attachment and entry. New access to complete genome sequences and ongoing advances in genetic manipulation should provide fertile ground for refining current models and defining exciting new roles for MICs in apicomplexan biology.
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Affiliation(s)
- Vern B Carruthers
- Department of Microbiology and Immunology, University of Michigan School of Medicine, Ann Arbor, Michigan 48109, USA.
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Persson KEM, Lee CT, Marsh K, Beeson JG. Development and optimization of high-throughput methods to measure Plasmodium falciparum-specific growth inhibitory antibodies. J Clin Microbiol 2006; 44:1665-73. [PMID: 16672391 PMCID: PMC1479166 DOI: 10.1128/jcm.44.5.1665-1673.2006] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antibodies that inhibit replication of Plasmodium falciparum in erythrocytes are thought to be important both in acquired immunity to malaria and as mediators of immunity generated by candidate blood-stage vaccines. However, several constraints have limited the study of these functional antibodies in population studies and vaccine trials. We report the development and optimization of high-throughput growth inhibition assays with improved sensitivity that use minimal volumes of test serum. The major inhibitory activity of serum from exposed donors was antibody mediated, but nonspecific inhibitory factors were found in untreated serum. Culture volumes could be effectively reduced to 25 microl to limit amounts of test serum or inhibitors used in assays. Performing inhibition assays over two cycles of parasite replication gave greater sensitivity than single-cycle assays, and a simple two-cycle inhibition assay was developed that yielded highly reproducible results. Determination of parasite growth by flow cytometry was most suitable for high-throughput assays using small culture volumes and was more sensitive than parasite lactate dehydrogenase assays and less prone to error and variation than microscopy. We evaluated and optimized methods to remove antimalarials and nonspecific inhibitory factors from serum that are suitable for use with small volumes of samples that are typically obtained from clinical studies. Both microdialysis and immunoglobulin purification by ammonium sulfate precipitation were effective and practical. These methods should facilitate evaluation of vaccine trials and clinical studies of immunity and are also suitable for testing drugs and other compounds for antimalarial activity.
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Affiliation(s)
- Kristina E M Persson
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
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Verra F, Chokejindachai W, Weedall GD, Polley SD, Mwangi TW, Marsh K, Conway DJ. Contrasting signatures of selection on the Plasmodium falciparum erythrocyte binding antigen gene family. Mol Biochem Parasitol 2006; 149:182-90. [PMID: 16837078 DOI: 10.1016/j.molbiopara.2006.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 05/12/2006] [Accepted: 05/30/2006] [Indexed: 10/24/2022]
Abstract
Erythrocyte binding antigens of Plasmodium falciparum are involved in erythrocyte invasion, and may be targets of acquired immunity. Of the five eba genes, protein products have been detected for eba-175, eba-181 and eba-140, but not for psieba-165 or ebl-1, providing opportunity for comparative analysis of genetic variation to identify selection. Region II of each of these genes was sequenced from a cross-sectional sample of parasites in an endemic Kenyan population, and the frequency distributions of polymorphisms analysed. A positive value of Tajima's D was observed for eba-175 (D=1.13) indicating an excess of intermediate frequency polymorphisms, while all other genes had negative values, the most negative being ebl-1 (D=-2.35) followed by psieba-165 (D=-1.79). The eba-175 and ebl-1 genes were then studied in a sample of parasites from Thailand, for which a positive Tajima's D value was again observed for eba-175 (D=1.79), and a negative value for ebl-1 (D=-1.85). This indicates that eba-175 is under balancing selection in each population, in strong contrast to the other members of the gene family, particularly ebl-1 and psieba-165 that may have been under recent directional selection. Population expansion simulations were performed under a neutral model, further supporting the departures from neutrality of these genes.
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Affiliation(s)
- Federica Verra
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom.
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Abstract
The clinical manifestations of Plasmodium falciparum malaria are directly linked to the blood stage of the parasite life cycle. At the blood stage, the circulating merozoites invade erythrocytes via a specific invasion pathway often identified with its dependence or independence on sialic acid residues of the host receptor. The invasion process involves multiple receptor-ligand interactions that mediate a complex series of events in a period of approximately 1 min. Although the mechanism by which merozoites invade erythrocytes is not fully understood, recent advances have put a new perspective on the importance of developing a multivalent blood stage-malaria vaccine. In this review, we highlight the role of currently identified host invasion receptors in blood-stage malaria.
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Affiliation(s)
- S S Oh
- Division of Cell Biology, Caritas St. Elizabeth's Medical Center, Tufts University School of Medicine, 736 Cambridge Street, Boston, MA 02135, USA
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41
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Touré FS, Deloron P, Migot-Nabias F. Analysis of human antibodies to erythrocyte binding antigen 175 peptide 4 of Plasmodium falciparum. Clin Med Res 2006; 4:1-6. [PMID: 16595787 PMCID: PMC1435654 DOI: 10.3121/cmr.4.1.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND The IgG1 and IgG3 antibodies are considered cytophilic and protective against Plasmodium falciparum, whereas IgG2 and IgG4 are thought to block protective mechanisms. OBJECTIVES The main objective was to measure antibodies directed against erythrocyte binding antigen-175 (EBA-175) peptide 4 and analyze the relationship between such antibodies and clinical malaria attack. METHODS Using an enzyme-linked immunosorbent assay, a retrospective analysis of naturally acquired antibodies to synthetic peptide from EBA-175 peptide 4 has been carried out in 158 school children from the village of Dienga in Gabon. RESULTS The overall prevalence rates of antibodies to EBA-175 peptide 4 were 85.2%, 66.8%, 52.6%, 71.6% and 64.0% for total IgG, IgG1, IgG2, IgG3 and IgG4, respectively. Protection from clinical malaria, determined after a prospective 1-year study, was associated with the levels of IgG and IgG1 antibodies that increased with age. CONCLUSION Together, these data suggest that age/exposure-related acquisition of anti-EBA-175 antibodies may contribute to the development of clinically protective immunity and could be taken into account in malaria control strategies when they are confirmed.
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Affiliation(s)
- Fousseyni S Touré
- Centre International de Recherches, Médicales de Franceville, BP 769 Franceville, Gabon.
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42
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Waters AP. Plasmodium's sticky fingers. Cell 2005; 122:149-51. [PMID: 16051139 DOI: 10.1016/j.cell.2005.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The life cycle of the malaria parasite (Plasmodium) is remarkably complex. Malaria parasites must engage in highly specific and varied interactions with cell types of both the mammalian host and the mosquito vector. In this issue of Cell, report detailed molecular insights into an intimate interaction between a malaria parasite protein and its host cell receptor that enables the parasite to invade erythrocytes.
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Affiliation(s)
- Andrew P Waters
- Malaria Group, Department of Parasitology, Centre of Infectious Diseases, Leiden University Medical Centre, The Netherlands
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Chelimo K, Ofulla AV, Narum DL, Kazura JW, Lanar DE, John CC. Antibodies to Plasmodium falciparum antigens vary by age and antigen in children in a malaria-holoendemic area of Kenya. Pediatr Infect Dis J 2005; 24:680-4. [PMID: 16094220 DOI: 10.1097/01.inf.0000172151.28851.fd] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Antibodies are important in protection against infection and disease caused by Plasmodium falciparum, but the frequencies of antibodies to multiple P. falciparum antigens in children are not well-characterized. METHODS IgG and IgM antibodies to the vaccine candidate antigens circumsporozoite protein, thrombospondin-related adhesive protein, liver stage antigen-1, apical membrane antigen-1, erythrocyte-binding antigen-175 and merozoite surface protein-1 were measured by enzyme-linked immunosorbent assay in 110 children 0-50 months of age in a malaria holoendemic area of Kenya. RESULTS A similar pattern was seen for IgG antibodies to circumsporozoite protein, thrombospondin-related adhesive protein, apical membrane antigen-1 and erythrocyte-binding antigen-175: high frequencies (70-90%) in children 0-4 months of age; a decrease in children 5-20 months of age (35-71%); and progressive increases in children 21-36 and 37-50 months of age (53-80% and 60-100%, respectively). In contrast, IgG antibodies to liver stage antigen-1 were infrequent in children 0-4 months of age (5%) and increased with age to 64%, and IgG antibody frequencies to merozoite surface protein-1 were similar across age groups (26-52%). IgG antibodies to all antigens were predominantly of the IgG1 and IgG3 subclasses. Frequencies of IgM antibodies to all antigens were low in children 0-4 months of age (0-15%) and increased with age (24-56% in the oldest children). CONCLUSION In children in a malaria-holoendemic area, IgM antibody to all P. falciparum antigens is infrequent in the first 4 months of life but increases with age and increased exposure. The pattern of age-related IgG response frequencies to P. falciparum antigens varies significantly by antigen.
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44
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Curtidor H, Rodríguez LE, Ocampo M, López R, García JE, Valbuena J, Vera R, Puentes A, Vanegas M, Patarroyo ME. Specific erythrocyte binding capacity and biological activity of Plasmodium falciparum erythrocyte binding ligand 1 (EBL-1)-derived peptides. Protein Sci 2005; 14:464-73. [PMID: 15659376 PMCID: PMC2254251 DOI: 10.1110/ps.041084305] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Erythrocyte binding ligand 1 (EBL-1) is a member of the ebl multigene family involved in Plasmodium falciparum invasion of erythrocytes. We found that five EBL-1 high-activity binding peptides (HABPs) bound specifically to erythrocytes: 29895 ((41)HKKKSGELNNNKSGILRSTY(60)), 29903 ((201)LYECGK-KIKEMKWICTDNQF(220)), 29923 ((601)CNAILGSYADIGDIVRGLDV(620)), 29924((621)WRDINTNKLSEK-FQKIFMGGY(640)), and 30018 ((2481)LEDIINLSKKKKKSINDTSFY(2500)). We also show that binding was saturable, not sialic acid-dependent, and that all peptides specifically bound to a 36-kDa protein on the erythrocyte membrane. The five HABPs inhibited in vitro merozoite invasion depending on the peptide concentration used, suggesting their possible role in the invasion process.
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Affiliation(s)
- Hernando Curtidor
- Fundación Instituto de Inmunología de Colombia, Carrera 50 No. 26-00, Bogotá, Colombia.
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Singh AP, Ozwara H, Kocken CHM, Puri SK, Thomas AW, Chitnis CE. Targeted deletion ofPlasmodium knowlesiDuffy binding protein confirms its role in junction formation during invasion. Mol Microbiol 2005; 55:1925-34. [PMID: 15752210 DOI: 10.1111/j.1365-2958.2005.04523.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Red cell invasion by Plasmodium merozoites involves multiple steps such as attachment, apical reorientation, junction formation and entry into a parasitophorous vacuole. These steps are mediated by specific molecular interactions. P. vivax and the simian parasite P. knowlesi require interaction with the Duffy blood group antigen to invade human erythrocytes. P. vivax and P. knowlesi Duffy binding proteins (PvDBP and PkDBP), which bind the Duffy antigen during invasion, share regions of sequence homology and belong to a family of erythrocyte binding proteins (EBPs). By deletion of the gene that encodes PkDBP, we demonstrate that interaction of PkDBP with the Duffy antigen is absolutely necessary for invasion of human erythrocytes by P. knowlesi. Electron microscopy studies reveal that PkDBP knockout parasites are unable to form a junction with human erythrocytes. The interaction of PkDBP with the Duffy antigen is thus necessary for the critical step of junction formation during invasion. These studies provide support for development of intervention strategies that target EBPs to inhibit junction formation and block erythrocyte invasion by malaria parasites.
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Affiliation(s)
- Agam P Singh
- Malaria Research Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Cifuentes G, Salazar LM, Vargas LE, Parra CA, Vanegas M, Cortes J, Patarroyo ME. Evidence supporting the hypothesis that specifically modifying a malaria peptide to fit into HLA-DRβ1*03 molecules induces antibody production and protection. Vaccine 2005; 23:1579-87. [PMID: 15694510 DOI: 10.1016/j.vaccine.2004.08.052] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Accepted: 08/10/2004] [Indexed: 11/26/2022]
Abstract
EBA-175 protein is used as ligand in Plasmodium falciparum binding to erythrocytes. Evidence shows that conserved peptide 1815 from this protein having high red blood cell binding ability plays an important role in the invasion process. This peptide is neither immunogenic nor protective. Residues were substituted by amino acids having similar volume or mass but different polarity in 1815 analogues had to make them fit into HLA-DRbeta1*03 molecules; these were synthesised and inoculated into Aotus monkeys, generating different immunogenic and/or protective immune responses. A shortening in alpha-helix structure was found in the immunogenic and protective ones when their secondary structure was analyzed by NMR to correlate their structure with their immunological properties. This data, together with results from previous studies, suggests that this shortening in high-activity binding peptide (HABP) helical configuration may lead to better fitting into immune system molecules as shown by binding to purified HLA-DRbeta1* molecules rendering them immunogenic and protective and therefore, excellent candidates for consideration as components of a subunit based multi-component synthetic vaccine against malaria.
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Affiliation(s)
- Gladys Cifuentes
- Fundación Instituto de Inmunología de Colombia (FIDIC), Cra. 50, No. 26-00, Bogotá, Colombia
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Choe H, Moore MJ, Owens CM, Wright PL, Vasilieva N, Li W, Singh AP, Shakri R, Chitnis CE, Farzan M. Sulphated tyrosines mediate association of chemokines and Plasmodium vivax Duffy binding protein with the Duffy antigen/receptor for chemokines (DARC). Mol Microbiol 2005; 55:1413-22. [PMID: 15720550 DOI: 10.1111/j.1365-2958.2004.04478.x] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Plasmodium vivax is one of four Plasmodium species that cause human malaria. P. vivax and a related simian malaria parasite, Plasmodium knowlesi, invade erythrocytes by binding the Duffy antigen/receptor for chemokines (DARC) through their respective Duffy binding proteins. Here we show that tyrosines 30 and 41 of DARC are modified by addition of sulphate groups, and that the sulphated tyrosine 41 is essential for association of the Duffy binding proteins of P. vivax (PvDBP) and P. knowlesi (PkDaBP) with DARC-expressing cells. These sulphated tyrosines also participate in the association of DARC with each of its four known chemokine ligands. Alteration of tyrosine 41 to phenylalanine interferes with MCP-1, RANTES and MGSA association with DARC, but not with that of IL8. In contrast, alteration of tyrosine 30 to phenylalanine interferes with the association of IL8 with DARC. A soluble sulphated amino-terminal domain of DARC, but not one modified to phenylalanine at residue 41, can be used to block the association of PvDBP and PkDaBP with red blood cells, with an IC50 of approximately 5 nM. These data are consistent with a role for tyrosine sulphation in the association of many or most chemokines with their receptors, and identify a key molecular determinant of erythrocyte invasion by P. vivax.
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Affiliation(s)
- Hyeryun Choe
- Perlmutter Laboratory, Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
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Gaffar FR, Franssen FFJ, de Vries E. Babesia bovis merozoites invade human, ovine, equine, porcine and caprine erythrocytes by a sialic acid-dependent mechanism followed by developmental arrest after a single round of cell fission. Int J Parasitol 2004; 33:1595-603. [PMID: 14636675 DOI: 10.1016/s0020-7519(03)00254-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Babesia bovis infections have only been observed in bovine species in contrast to Babesia divergens that also can infect humans, sheep and rodents. Using an in vitro assay that assesses invasion of erythrocytes by free merozoites after a 1-h incubation period, it was shown that specificity is not determined by host-specific interactions associated with invasion. Human erythrocytes were invaded more efficiently than bovine erythrocytes whereas erythrocytes of sheep, pigs and horses were invaded only slightly less efficiently. In contrast, goat erythrocytes were refractory to efficient invasion. Significant differences in invasion efficiency into erythrocytes from different individuals of the same species were observed. Erythrocytes from all species, except for goats, supported intracellular development of newly invaded merozoites and high numbers of duplicated parasites, located in a morphologically normal accole position, were present. Only in bovine erythrocytes did subsequent rounds of invasion, leading to increased parasitaemia, take place. This suggests that host specificity is determined by factors operating late in the erythrocytic stage of the B. bovis life cycle. Incubation of erythrocytes with neuraminidase prior to invasion led to a decrease in invasion efficiency of approximately 80%. This effect was observed for several species. The removal of either alpha(2-3)-linked or alpha(2-6)-linked sialic acid residues gave similar levels of reduction whereas simultaneous removal did not show an additive effect. Pre-incubation of merozoites with N-acetylneuraminyl-lactose decreased invasion efficiency by approximately 45% whereas addition just prior to invasion had no significant effect. The results demonstrate that invasion is dependent on the presence of sialic-acid containing membrane receptors on erythrocytes that interact with merozoite ligands that are probably already accessible during pre-incubation prior to invasion.
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Affiliation(s)
- Fasila R Gaffar
- Division of Parasitology and Tropical Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, P.O. Box 80165, 3508 TD Utrecht, The Netherlands
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Ohas EA, Adams JH, Waitumbi JN, Orago ASS, Barbosa A, Lanar DE, Stoute JA. Measurement of antibody levels against region II of the erythrocyte-binding antigen 175 of Plasmodium falciparum in an area of malaria holoendemicity in western Kenya. Infect Immun 2004; 72:735-41. [PMID: 14742515 PMCID: PMC321612 DOI: 10.1128/iai.72.2.735-741.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Region II of the 175-kDa erythrocyte-binding antigen (EBA-175RII) of Plasmodium falciparum is functionally important in sialic acid-dependent erythrocyte invasion and is considered a prime target for an invasion-blocking vaccine. The objectives of this study were to (i) determine the prevalence of anti-EBA-175RII antibodies in a naturally exposed population, (ii) determine whether naturally acquired antibodies have a functional role by inhibiting binding of EBA-175RII to erythrocytes, and (iii) determine whether antibodies against EBA-175RII correlate with immunity to clinical malaria. We treated 301 lifelong residents of an area of malaria holoendemicity in western Kenya for malaria, monitored them during a high-transmission season, and identified 33 individuals who were asymptomatic despite parasitemia (clinically immune). We also identified 50 clinically susceptible individuals to serve as controls. These 83 individuals were treated and monitored again during the subsequent low-transmission season. Anti-EBA-175RII antibodies were present in 98.7% of the individuals studied. The antibody levels were relatively stable between the beginning and end of the high-transmission season and correlated with the plasma EBA-175RII erythrocyte-binding-inhibitory activity. There was no difference in anti-EBA-175RII levels or plasma EBA-175RII erythrocyte-binding-inhibitory activity between clinically immune and clinically susceptible groups. However, these parameters were higher in nonparasitemic than in parasitemic individuals at enrollment. These results suggest that although antibodies against EBA-175RII may be effective in suppressing some of the wild parasite strains, EBA-175RII is unlikely to be effective as a monovalent vaccine against malaria, perhaps due to allelic heterogeneity and/or presence of sialic acid-independent strains.
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Affiliation(s)
- Eunita A Ohas
- U.S. Army Medical Research Unit and Kenya Medical Research Institute, Nairobi, Kenya
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Chauhan VS, Bhardwaj D. Current status of malaria vaccine development. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2003; 84:143-82. [PMID: 12934936 DOI: 10.1007/3-540-36488-9_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
There is an urgent need to develop an effective vaccine against malaria--a disease that has approximately 10% of the world population at risk of infection at any given time. The economic burden this disease puts on the medico-social set-up of countries in Sub-Saharan Africa and South East Asia is phenomenal. Increasing drug resistance and failure of vector control strategies have necessitated the search for a suitable vaccine that could be integrated into the extended program of immunization for countries in the endemic regions. Malaria vaccine development has seen a surge of activity in the last decade or so owing largely to the advances made in the fields of genetic engineering and biotechnology. This revolution has brought sweeping changes in the understanding of the biology of the parasite and has helped formulate newer more effective strategies to combat the disease. Latest developments in the field of malaria vaccine development will be discussed in this chapter.
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Affiliation(s)
- Virander Singh Chauhan
- Malaria Research Group, International Center for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India.
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