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Freville A, Stewart LB, Tetteh KKA, Treeck M, Cortes A, Voss TS, Tarr SJ, Baker DA, Conway DJ. Expression of the MSPDBL2 antigen in a discrete subset of Plasmodium falciparum schizonts is regulated by GDV1 but may not be linked to sexual commitment. mBio 2024; 15:e0314023. [PMID: 38530030 PMCID: PMC11077968 DOI: 10.1128/mbio.03140-23] [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: 11/21/2023] [Accepted: 03/04/2024] [Indexed: 03/27/2024] Open
Abstract
The Plasmodium falciparum merozoite surface protein MSPDBL2 is a polymorphic antigen targeted by acquired immune responses, and normally expressed in only a minority of mature schizonts. The potential relationship of MSPDBL2 to sexual commitment is examined, as variable mspdbl2 transcript levels and proportions of MSPDBL2-positive mature schizonts in clinical isolates have previously correlated with levels of many sexual stage parasite gene transcripts, although not with the master regulator ap2-g. It is demonstrated that conditional overexpression of the gametocyte development protein GDV1, which promotes sexual commitment, also substantially increases the proportion of MSPDBL2-positive schizonts in culture. Conversely, truncation of the gdv1 gene is shown to prevent any expression of MSPDBL2. However, across diverse P. falciparum cultured lines, the variable proportions of MSPDBL2 positivity in schizonts do not correlate significantly with variable gametocyte conversion rates, indicating it is not involved in sexual commitment. Confirming this, examining a line with endogenous hemagglutinin-tagged AP2-G showed that the individual schizonts expressing MSPDBL2 are mostly different from those expressing AP2-G. Using a selection-linked integration system, modified P. falciparum lines were engineered to express an intact or disrupted version of MSPDBL2, showing the protein is not required for sexual commitment or early gametocyte development. Asexual parasite multiplication rates were also not affected by expression of either intact or disrupted MSPDBL2 in a majority of schizonts. Occurring alongside sexual commitment, the role of the discrete MSPDBL2-positive schizont subpopulation requires further investigation in natural infections where it is under immune selection. IMPORTANCE Malaria parasites in the blood are remarkably variable, able to switch antigenic targets so they may survive within humans who have already developed specific immune responses. This is one of the challenges in developing vaccines against malaria. MSPDBL2 is a target of naturally acquired immunity expressed in minority proportions of schizonts, the end stages of each 2-day replication cycle in red blood cells which contain merozoites prepared to invade new red blood cells. Results show that the proportion of schizonts expressing MSPDBL2 is positively controlled by the expression of the regulatory gametocyte development protein GDV1. It was previously known that expression of GDV1 leads to increased expression of AP2-G which causes parasites to switch to sexual development, so a surprising finding here is that MSPDBL2-positive parasites are mostly distinct from those that express AP2-G. This discrete antigenic subpopulation of mostly asexual parasites is regulated alongside sexually committed parasites, potentially enabling survival under stress conditions.
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Affiliation(s)
- Aline Freville
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Lindsay B. Stewart
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Kevin K. A. Tetteh
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Alfred Cortes
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Catalonia, Spain
- ICREA, Barcelona, Catalonia, Spain
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Sarah J. Tarr
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David A. Baker
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David J. Conway
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Ogwang R, Murugu L, Nkumama IN, Nyamako L, Kai O, Mwai K, Murungi L, Idro R, Bejon P, Tuju J, Kinyanjui SM, Osier FHA. Bi-isotype immunoglobulins enhance antibody-mediated neutrophil activity against Plasmodium falciparum parasites. Front Immunol 2024; 15:1360220. [PMID: 38650925 PMCID: PMC11033408 DOI: 10.3389/fimmu.2024.1360220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/19/2024] [Indexed: 04/25/2024] Open
Abstract
Background Malaria remains a major global health priority, and monoclonal antibodies (mAbs) are emerging as potential new tools to support efforts to control the disease. Recent data suggest that Fc-dependent mechanisms of immunity are important mediators of protection against the blood stages of the infection, but few studies have investigated this in the context of mAbs. We aimed to isolate mAbs agnostic to cognate antigens that target whole merozoites and simultaneously induce potent neutrophil activity measured by the level of reactive oxygen species (ROS) production using an antibody-dependent respiratory burst (ADRB) assay. Methods We used samples from semi-immune adults living in coastal Kenya to isolate mAbs that induce merozoite-specific ADRB activity. We then tested whether modifying the expressed IgG1 isotype to an IgG-IgA Fc region chimera would enhance the level of ADRB activity. Results We isolated a panel of nine mAbs with specificity to whole merozoites. mAb J31 induced ADRB activity in a dose-dependent fashion. Compared to IgG1, our modified antibody IgG-IgA bi-isotype induced higher ADRB activity across all concentrations tested. Further, we observed a negative hook effect at high IgG1 mAb concentrations (i.e., >200 µg/mL), but this was reversed by Fc modification. We identified MSP3.5 as the potential cognate target of mAb J31. Conclusions We demonstrate an approach to engineer mAbs with enhanced ADRB potency against blood-stage parasites.
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Affiliation(s)
- Rodney Ogwang
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Lewis Murugu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Irene N. Nkumama
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Lydia Nyamako
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Oscar Kai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kennedy Mwai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Linda Murungi
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Richard Idro
- College of Health Sciences, Makerere University, Kampala, Uganda
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - James Tuju
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Sam Muchina Kinyanjui
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Faith H. A. Osier
- Department of Life Sciences, Imperial College London, London, United Kingdom
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Zhou X, Zhang Q, Chen JH, Dai JF, Kassegne K. Revisiting the antigen markers of vector-borne parasitic diseases identified by immunomics: identification and application to disease control. Expert Rev Proteomics 2024; 21:205-216. [PMID: 38584506 DOI: 10.1080/14789450.2024.2336994] [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: 09/05/2023] [Accepted: 03/03/2024] [Indexed: 04/09/2024]
Abstract
INTRODUCTION Protein microarray is a promising immunomic approach for identifying biomarkers. Based on our previous study that reviewed parasite antigens and recent parasitic omics research, this article expands to include information on vector-borne parasitic diseases (VBPDs), namely, malaria, schistosomiasis, leishmaniasis, babesiosis, trypanosomiasis, lymphatic filariasis, and onchocerciasis. AREAS COVERED We revisit and systematically summarize antigen markers of vector-borne parasites identified by the immunomic approach and discuss the latest advances in identifying antigens for the rational development of diagnostics and vaccines. The applications and challenges of this approach for VBPD control are also discussed. EXPERT OPINION The immunomic approach has enabled the identification and/or validation of antigen markers for vaccine development, diagnosis, disease surveillance, and treatment. However, this approach presents several challenges, including limited sample size, variability in antigen expression, false-positive results, complexity of omics data, validation and reproducibility, and heterogeneity of diseases. In addition, antigen involvement in host immune evasion and antigen sensitivity/specificity are major issues in its application. Despite these limitations, this approach remains promising for controlling VBPD. Advances in technology and data analysis methods should continue to improve candidate antigen identification, as well as the use of a multiantigen approach in diagnostic and vaccine development for VBPD control.
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Affiliation(s)
- Xia Zhou
- MOE Key Laboratory of Geriatric Diseases and Immunology, School of Biology & Basic Medical Science, Suzhou Medical College of Soochow University, Suzhou, China
| | - Qianqian Zhang
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Jun-Hu Chen
- National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases, National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology; World Health Organization (WHO) Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, People's Republic of China
- Hainan Tropical Diseases Research Center (Hainan Sub-Center, Chinese Center for Tropical Diseases Research), Haikou, China
| | - Jian-Feng Dai
- Institute of Biology and Medical Sciences, Jiangsu Key Laboratory of Infection and Immunity, Soochow University, Suzhou, China
| | - Kokouvi Kassegne
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- One Health Center, Shanghai Jiao Tong University, Shanghai, China
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Highly Variable Expression of Merozoite Surface Protein MSPDBL2 in Diverse Plasmodium falciparum Clinical Isolates and Transcriptome Scans for Correlating Genes. mBio 2022; 13:e0194822. [PMID: 35950755 PMCID: PMC9426457 DOI: 10.1128/mbio.01948-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The merozoite surface protein MSPDBL2 of Plasmodium falciparum is under strong balancing selection and is a target of naturally acquired antibodies. Remarkably, MSPDBL2 is expressed in only a minority of mature schizonts of any cultured parasite line, and mspdbl2 gene transcription increases in response to overexpression of the gametocyte development inducer GDV1, so it is important to understand its natural expression. Here, MSPDBL2 in mature schizonts was analyzed in the first ex vivo culture cycle of 96 clinical isolates from 4 populations with various levels of infection endemicity in different West African countries, by immunofluorescence microscopy with antibodies against a conserved region of the protein. In most isolates, less than 1% of mature schizonts were positive for MSPDBL2, but the frequency distribution was highly skewed, as nine isolates had more than 3% schizonts positive and one had 73% positive. To investigate whether the expression of other gene loci correlated with MSPDBL2 expression, whole-transcriptome sequencing was performed on schizont-enriched material from 17 of the isolates with a wide range of proportions of schizonts positive. Transcripts of particular genes were highly significantly positively correlated with MSPDBL2 positivity in schizonts as well as with mspdbl2 gene transcript levels, showing overrepresentation of genes implicated previously as involved in gametocytogenesis but not including the gametocytogenesis master regulator ap2-g. Single-cell transcriptome analysis of a laboratory-adapted clone showed that most individual parasites expressing mspdbl2 did not express ap2-g, consistent with MSPDBL2 marking a developmental subpopulation that is distinct but likely to co-occur alongside sexual commitment. IMPORTANCE These findings contribute to understanding malaria parasite antigenic and developmental variation, focusing on the merozoite surface protein encoded by the single locus under strongest balancing selection. Analyzing the initial ex vivo generation of parasites grown from a wide sample of clinical infections, we show a unique and highly skewed pattern of natural expression frequencies of MSPDBL2, distinct from that of any other antigen. Bulk transcriptome analysis of a range of clinical isolates showed significant overrepresentation of sexual development genes among those positively correlated with MSPDBL2 protein and mspdbl2 gene expression, indicating the MSPDBL2-positive subpopulation to be often coincident with parasites developing sexually in preparation for transmission. Single-cell transcriptome data confirm the absence of a direct correlation with the ap2-g master regulator of sexual development, indicating that the MSPDBL2-positive subpopulation has a separate function in asexual survival and replication under conditions that promote terminal sexual differentiation.
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Aniweh Y, Nyarko PB, Charles-Chess E, Ansah F, Osier FHA, Quansah E, Thiam LG, Kamuyu G, Marsh K, Conway DJ, Tetteh KKA, Awandare GA. Plasmodium falciparum Merozoite Associated Armadillo Protein (PfMAAP) Is Apically Localized in Free Merozoites and Antibodies Are Associated With Reduced Risk of Malaria. Front Immunol 2020; 11:505. [PMID: 32318061 PMCID: PMC7155890 DOI: 10.3389/fimmu.2020.00505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 03/05/2020] [Indexed: 11/19/2022] Open
Abstract
Understanding the functional role of proteins expressed by Plasmodium falciparum is an important step toward unlocking potential targets for the development of therapeutic or diagnostic interventions. The armadillo (ARM) repeat protein superfamily is associated with varied functions across the eukaryotes. Therefore, it is important to understand the role of members of this protein family in Plasmodium biology. The Plasmodium falciparum armadillo repeats only (PfARO; Pf3D7_0414900) and P. falciparum merozoite organizing proteins (PfMOP; Pf3D7_0917000) are armadillo-repeat containing proteins previously characterized in P. falciparum. Here, we describe the characterization of another ARM repeat-containing protein in P. falciparum, which we have named the P. falciparum Merozoites-Associated Armadillo repeats protein (PfMAAP). Antibodies raised to three different synthetic peptides of PfMAAP show apical staining of free merozoites and those within the mature infected schizont. We also demonstrate that the antibodies raised to the PfMAAP peptides inhibited invasion of erythrocytes by merozoites from different parasite isolates. In addition, naturally acquired human antibodies to the N- and C- termini of PfMAAP are associated with a reduced risk of malaria in a prospective cohort analysis.
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Affiliation(s)
- Yaw Aniweh
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Prince B. Nyarko
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Essel Charles-Chess
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Felix Ansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Faith H. A. Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
- Department of Biochemistry, Pwani University, Kilifi, Kenya
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Evelyn Quansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Laty Gaye Thiam
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Gathoni Kamuyu
- Division of Medicine, Department of Respiratory Medicine, UCL, London, United Kingdom
| | - Kevin Marsh
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - David J. Conway
- Department of Infection Biology, London School of Tropical Medicine and Hygiene, London, United Kingdom
| | - Kevin K. A. Tetteh
- Department of Infection Biology, London School of Tropical Medicine and Hygiene, London, United Kingdom
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
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Peripheral Merozoite Surface Proteins Are Targets of Naturally Acquired Immunity against Malaria in both India and Ghana. Infect Immun 2020; 88:IAI.00778-19. [PMID: 31964745 DOI: 10.1128/iai.00778-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 01/14/2020] [Indexed: 01/25/2023] Open
Abstract
Development of a successful blood-stage vaccine against Plasmodium falciparum malaria remains a high priority. Immune-epidemiological studies are effective tools for the identification of antigenic targets of naturally acquired immunity (NAI) against malaria. However, differences in study design and methodology may compromise interstudy comparisons. Here, we assessed antibody responses against intact merozoites and a panel of 24 recombinant merozoite antigens in longitudinal cohort studies of Ghanaian (n = 115) and Indian (n = 121) populations using the same reagents and statistical methods. Anti-merozoite antibodies were associated with NAI in both the Indian (hazard ratio [HR] = 0.41, P = 0.020) and the Ghanaian (HR = 0.17, P < 0.001) participants. Of the 24 antigen-specific antibodies quantified, 12 and 8 were found to be protective in India and Ghana, respectively. Using least absolute shrinkage and selection operator (LASSO) regression, a powerful variable subselection technique, we identified subsets of four (MSP6, MSP3.7, MSPDBL2, and Pf12) and five (cMSP33D7, MSP3.3, MSPDBL1, GLURP-R2, and RALP-1) antigens that explained NAI better than the individual antibodies in India (HR = 0.18, P < 0.001) and Ghana (HR = 0.31, P < 0.001), respectively. IgG1 and/or IgG3 subclasses against five antigens from these subsets were associated with protection. Through this comparative study, maintaining uniformity of reagents and methodology, we demonstrate that NAI across diverse geographic regions may result from antibodies to multiple antigenic targets that constitute the peripheral merozoite surface protein complexes.
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Farias LP, Chalmers IW, Perally S, Rofatto HK, Jackson CJ, Brown M, Khouri MI, Barbosa MMF, Hensbergen PJ, Hokke CH, Leite LCC, Hoffmann KF. Schistosoma mansoni venom allergen-like proteins: phylogenetic relationships, stage-specific transcription and tissue localization as predictors of immunological cross-reactivity. Int J Parasitol 2019; 49:593-599. [PMID: 31136745 PMCID: PMC6598858 DOI: 10.1016/j.ijpara.2019.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/25/2019] [Accepted: 03/28/2019] [Indexed: 12/11/2022]
Abstract
The Schistosoma mansoni venom allergen-like (SmVAL) family relationships were investigated. Transcription patterns of SmVALs associate with phylogenetic relationships. There was clear antibody cross-reactivity between related native SmVAL proteins. SmVAL4, 10, 18 and 19 all localized via WISH to pre-acetabular glands of cercariae.
Schistosoma mansoni venom allergen-like proteins (SmVALs) are part of a diverse protein superfamily partitioned into two groups (group 1 and group 2). Phylogenetic analyses of group 1 SmVALs revealed that members could be segregated into subclades (A–D); these subclades share similar gene expression patterns across the parasite lifecycle and immunological cross-reactivity. Furthermore, whole-mount in situ hybridization demonstrated that the phylogenetically, transcriptionally and immunologically-related SmVAL4, 10, 18 and 19 (subclade C) were all localized to the pre-acetabular glands of immature cercariae. Our results suggest that SmVAL group 1 phylogenetic relationships, stage-specific transcriptional profiles and tissue localization are predictive of immunological cross-reactivity.
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Affiliation(s)
- Leonardo P Farias
- Centro de Biotecnologia, Instituto Butantan, Av. Vital Brasil, 1500, 05503-900 São Paulo, SP, Brazil; Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Rua Waldemar Falcão, Salvador, Bahia, Brazil
| | - Iain W Chalmers
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, SY23 3FG Aberystwyth, UK
| | - Samirah Perally
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, SY23 3FG Aberystwyth, UK
| | - Henrique K Rofatto
- Centro de Biotecnologia, Instituto Butantan, Av. Vital Brasil, 1500, 05503-900 São Paulo, SP, Brazil
| | - Colin J Jackson
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, SY23 3FG Aberystwyth, UK
| | - Martha Brown
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, SY23 3FG Aberystwyth, UK
| | - Mariana I Khouri
- Instituto Gonçalo Moniz, Fundação Oswaldo Cruz (FIOCRUZ), Rua Waldemar Falcão, Salvador, Bahia, Brazil
| | - Mayra M F Barbosa
- Centro de Biotecnologia, Instituto Butantan, Av. Vital Brasil, 1500, 05503-900 São Paulo, SP, Brazil; Programa de Pós-Graduação Interunidades em Biotecnologia, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Paul J Hensbergen
- Center for Proteomics and Metabolomics, Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Cornelis H Hokke
- Department of Parasitology, Leiden University Medical Centre, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Luciana C C Leite
- Centro de Biotecnologia, Instituto Butantan, Av. Vital Brasil, 1500, 05503-900 São Paulo, SP, Brazil
| | - Karl F Hoffmann
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, SY23 3FG Aberystwyth, UK.
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Campino S, Marin-Menendez A, Kemp A, Cross N, Drought L, Otto TD, Benavente ED, Ravenhall M, Schwach F, Girling G, Manske M, Theron M, Gould K, Drury E, Clark TG, Kwiatkowski DP, Pance A, Rayner JC. A forward genetic screen reveals a primary role for Plasmodium falciparum Reticulocyte Binding Protein Homologue 2a and 2b in determining alternative erythrocyte invasion pathways. PLoS Pathog 2018; 14:e1007436. [PMID: 30496294 PMCID: PMC6289454 DOI: 10.1371/journal.ppat.1007436] [Citation(s) in RCA: 12] [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: 07/31/2018] [Revised: 12/11/2018] [Accepted: 10/24/2018] [Indexed: 12/14/2022] Open
Abstract
Invasion of human erythrocytes is essential for Plasmodium falciparum parasite survival and pathogenesis, and is also a complex phenotype. While some later steps in invasion appear to be invariant and essential, the earlier steps of recognition are controlled by a series of redundant, and only partially understood, receptor-ligand interactions. Reverse genetic analysis of laboratory adapted strains has identified multiple genes that when deleted can alter invasion, but how the relative contributions of each gene translate to the phenotypes of clinical isolates is far from clear. We used a forward genetic approach to identify genes responsible for variable erythrocyte invasion by phenotyping the parents and progeny of previously generated experimental genetic crosses. Linkage analysis using whole genome sequencing data revealed a single major locus was responsible for the majority of phenotypic variation in two invasion pathways. This locus contained the PfRh2a and PfRh2b genes, members of one of the major invasion ligand gene families, but not widely thought to play such a prominent role in specifying invasion phenotypes. Variation in invasion pathways was linked to significant differences in PfRh2a and PfRh2b expression between parasite lines, and their role in specifying alternative invasion was confirmed by CRISPR-Cas9-mediated genome editing. Expansion of the analysis to a large set of clinical P. falciparum isolates revealed common deletions, suggesting that variation at this locus is a major cause of invasion phenotypic variation in the endemic setting. This work has implications for blood-stage vaccine development and will help inform the design and location of future large-scale studies of invasion in clinical isolates. Plasmodium parasites cause more than 200 million cases of malaria each year. All the symptoms of malaria are caused after Plasmodium parasites invade human red blood cells. Once inside, they grow, multiply and break open the red blood cells to release new parasites. This cycle is repeated every 48 hours, rapidly amplifying the number of parasites and causing severe anemia and other complications. Plasmodium falciparum, the parasite species responsible for almost all malaria deaths, can use multiple different pathways to invade human red blood cells, but the relative importance of each is not well understood. We tested the invasion pathways used by a collection of closely related parasites and compared their genome sequences to identify the genes responsible. This analysis revealed that expression differences in two neighboring genes of the Reticulocyte Binding Homologue family are responsible for most of the variation in two invasion pathways. P. falciparum may use variation in these genes to avoid the immune system or adapt to specific blood groups, which has important implications for vaccine development against malaria.
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Affiliation(s)
- Susana Campino
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- * E-mail: (SC); (JCR)
| | - Alejandro Marin-Menendez
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Alison Kemp
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Nadia Cross
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Laura Drought
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Thomas D. Otto
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- Centre of Immunobiology, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Ernest Diez Benavente
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Matt Ravenhall
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Frank Schwach
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Gareth Girling
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Magnus Manske
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Michel Theron
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Kelda Gould
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Eleanor Drury
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Taane G. Clark
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Dominic P. Kwiatkowski
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Alena Pance
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Julian C. Rayner
- Malaria Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, United Kingdom
- * E-mail: (SC); (JCR)
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9
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Tohmoto T, Takashima E, Takeo S, Morita M, Nagaoka H, Udomsangpetch R, Sattabongkot J, Ishino T, Torii M, Tsuboi T. Anti-MSP11 IgG inhibits Plasmodium falciparum merozoite invasion into erythrocytes in vitro. Parasitol Int 2018; 69:25-29. [PMID: 30385417 DOI: 10.1016/j.parint.2018.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/18/2018] [Accepted: 10/29/2018] [Indexed: 11/19/2022]
Abstract
Merozoite surface proteins (MSPs) are considered as promising blood-stage malaria vaccine candidates. MSP3 has long been evaluated for its vaccine candidacy, however, the candidacy of other members of MSP3 family is insufficiently characterized. Here, we investigated Plasmodium falciparum MSP11 (PF3D7_1036000), a member of the MSP3 family, for its potential as a blood-stage vaccine candidate. The full-length protein (MSP11-FL) as well as the N-terminal half-MSP11 (MSP11-N), known to be unique among the MSP3 family members, were expressed by wheat germ cell-free system, and used to raise antibodies in rabbit. Immunoblot analysis of schizont lysates probed with anti-MSP11-N antibodies detected double bands at approximately 40 and 60 kDa, consistent with the previous report thus confirming antibodies specificity. However, inconsistent with previously reported merozoite's surface localization, immunofluorescence assay (IFA) revealed that MSP11 likely localizes to rhoptry neck of merozoites in mature schizonts. After invasion, MSP11 localized to parasitophorous vacuole and thereafter in Maurer's clefts in trophozoites. Anti-MSP11-FL antibody levels were significantly higher in asymptomatic than symptomatic P. falciparum cases in malaria low endemic Thailand. This reconfirmed that anti-MSP11 antibodies play an important role in protection against clinical malaria, as previously reported. Furthermore, in vitro growth inhibition assay revealed that anti-MSP11-FL rabbit antibodies biologically function by inhibiting merozoite invasion of erythrocytes. These findings further support the vaccine candidacy of MSP11.
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Affiliation(s)
- Tatsuhiro Tohmoto
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
| | - Satoru Takeo
- Division of Tropical Diseases and Parasitology, Department of Infectious Diseases, Faculty of Medicine, Kyorin University, Mitaka, Tokyo 181-8611, Japan
| | - Masayuki Morita
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Rachanee Udomsangpetch
- Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Salaya, Nakhosn Pathom 73170, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Tomoko Ishino
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Motomi Torii
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Shitsukawa, Toon, Ehime 791-0295, Japan
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
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10
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Plasmodium falciparum MSP3 Exists in a Complex on the Merozoite Surface and Generates Antibody Response during Natural Infection. Infect Immun 2018; 86:IAI.00067-18. [PMID: 29760216 DOI: 10.1128/iai.00067-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 05/01/2018] [Indexed: 12/22/2022] Open
Abstract
Plasmodium falciparum merozoite surface protein 3 (MSP3) is an abundantly expressed secreted merozoite surface protein and a leading malaria vaccine candidate antigen. However, it is unclear how MSP3 is retained on the surface of merozoites without a glycosylphosphatidylinositol (GPI) anchor or a transmembrane domain. In the present study, we identified an MSP3-associated network on the Plasmodium merozoite surface by immunoprecipitation of Plasmodium merozoite lysate using antibody to the N terminus of MSP3 (anti-MSP3N) followed by mass spectrometry analysis. The results suggested the association of MSP3 with other merozoite surface proteins: MSP1, MSP6, MSP7, RAP2, and SERA5. Protein-protein interaction studies by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR) analysis showed that MSP3 complex consists of MSP1, MSP6, and MSP7 proteins. Immunological characterization of MSP3 revealed that MSP3N is strongly recognized by hyperimmune serum from African and Asian populations. Furthermore, we demonstrate that human antibodies, affinity purified against recombinant MSP3N (rMSP3N), promote opsonic phagocytosis of merozoites in cooperation with monocytes. At nonphysiological concentrations, anti-MSP3N antibodies inhibited the growth of P. falciparum in vitro Together, the data suggest that MSP3 and especially its N-terminal region containing known B/T cell epitopes are targets of naturally acquired immunity against malaria and also comprise an important candidate for a multisubunit malaria vaccine.
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Merozoite Surface Protein 1 from Plasmodium falciparum Is a Major Target of Opsonizing Antibodies in Individuals with Acquired Immunity against Malaria. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00155-17. [PMID: 28877929 DOI: 10.1128/cvi.00155-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/31/2017] [Indexed: 11/20/2022]
Abstract
Naturally acquired immunity against malaria is largely mediated by serum antibodies controlling levels of blood-stage parasites. A limited understanding of the antigenic targets and functional mechanisms of protective antibodies has hampered the development of efficient malaria vaccines. Besides directly inhibiting the growth of Plasmodium parasites, antibodies can opsonize merozoites and recruit immune effector cells such as monocytes and neutrophils. Antibodies against the vaccine candidate merozoite surface protein 1 (MSP-1) are acquired during natural infections and have been associated with protection against malaria in several epidemiological studies. Here we analyzed serum antibodies from semi-immune individuals from Burkina Faso for their potential (i) to directly inhibit the growth of P. falciparum blood stages in vitro and (ii) to opsonize merozoites and to induce the antibody-dependent respiratory burst (ADRB) activity of neutrophils. While a few sera that directly inhibited the growth of P. falciparum blood stages were identified, immunoglobulin G (IgG) from all individuals clearly mediated the activation of neutrophils. The level of neutrophil activation correlated with levels of antibodies to MSP-1, and affinity-purified MSP-1-specific antibodies elicited ADRB activity. Furthermore, immunization of nonhuman primates with recombinant full-size MSP-1 induced antibodies that efficiently opsonized P. falciparum merozoites. Reversing the function by preincubation with recombinant antigens allowed us to quantify the contribution of MSP-1 to the antiparasitic effect of serum antibodies. Our data suggest that MSP-1, especially the partially conserved subunit MSP-183, is a major target of opsonizing antibodies acquired during natural exposure to malaria. Induction of opsonizing antibodies might be a crucial effector mechanism for MSP-1-based malaria vaccines.
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12
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Hill DL, Schofield L, Wilson DW. IgG opsonization of merozoites: multiple immune mechanisms for malaria vaccine development. Int J Parasitol 2017; 47:585-595. [PMID: 28668325 DOI: 10.1016/j.ijpara.2017.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 04/12/2017] [Accepted: 05/12/2017] [Indexed: 02/07/2023]
Abstract
Global eradication of the human-infecting malaria parasite Plasmodium falciparum, the major cause of malaria mortality, is unlikely to be achieved without an effective vaccine. However, our limited understanding of how protective immune responses target malaria parasites in humans, and how to best elicit these immune responses through vaccination, has hampered vaccine development. The red blood cell invading stage of the parasite lifecycle (merozoite) displays antigens that are attractive vaccine candidates as they are accessible to antibodies and raise high antibody titres in naturally immune individuals. The number of merozoite antigens that elicit an immune response, and their structural and functional diversity, has led to a large number of lead antigens being pursued as vaccine candidates. Despite being seemingly spoilt for choice in terms of vaccine candidates, there is still a lack of consensus on exactly how merozoite antibodies reduce parasitemia and malaria disease. In this review we describe the various immune mechanisms that can result from IgG opsonization of merozoites, and highlight recent developments that support a role for these functional antibodies in naturally acquired and vaccine-induced immunity.
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Affiliation(s)
- Danika L Hill
- Babraham Institute, Babraham Research Campus, Cambridge, United Kingdom; The Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia.
| | - Louis Schofield
- Australian Institute of Tropical Health and Medicine, James Cook University, Townsville, Australia
| | - Danny W Wilson
- Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, Australia; Burnet Institute, 85 Commercial Road, Melbourne 3004, Victoria, Australia.
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Kennedy AT, Wijeyewickrema LC, Huglo A, Lin C, Pike R, Cowman AF, Tham WH. Recruitment of Human C1 Esterase Inhibitor Controls Complement Activation on Blood StagePlasmodium falciparumMerozoites. THE JOURNAL OF IMMUNOLOGY 2017; 198:4728-4737. [DOI: 10.4049/jimmunol.1700067] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/10/2017] [Indexed: 11/19/2022]
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14
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Kassegne K, Abe EM, Chen JH, Zhou XN. Immunomic approaches for antigen discovery of human parasites. Expert Rev Proteomics 2016; 13:1091-1101. [DOI: 10.1080/14789450.2016.1252675] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Kokouvi Kassegne
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Tropical Diseases, National Center for International Research on Tropical Diseases, Key Laboratory of Parasite and Vector Biology of the Chinese Ministry of Health, Shanghai, People’s Republic of China
| | - Eniola Michael Abe
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Tropical Diseases, National Center for International Research on Tropical Diseases, Key Laboratory of Parasite and Vector Biology of the Chinese Ministry of Health, Shanghai, People’s Republic of China
| | - Jun-Hu Chen
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Tropical Diseases, National Center for International Research on Tropical Diseases, Key Laboratory of Parasite and Vector Biology of the Chinese Ministry of Health, Shanghai, People’s Republic of China
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Centre for Tropical Diseases, National Center for International Research on Tropical Diseases, Key Laboratory of Parasite and Vector Biology of the Chinese Ministry of Health, Shanghai, People’s Republic of China
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15
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Merozoite Antigens of Plasmodium falciparum Elicit Strain-Transcending Opsonizing Immunity. Infect Immun 2016; 84:2175-2184. [PMID: 27185785 DOI: 10.1128/iai.00145-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 05/11/2016] [Indexed: 02/06/2023] Open
Abstract
It is unclear whether naturally acquired immunity to Plasmodium falciparum results from the acquisition of antibodies to multiple, diverse antigens or to fewer, highly conserved antigens. Moreover, the specific antibody functions required for malaria immunity are unknown, and hence informative immunological assays are urgently needed to address these knowledge gaps and guide vaccine development. In this study, we investigated whether merozoite-opsonizing antibodies are associated with protection from malaria in a strain-specific or strain-transcending manner by using a novel field isolate and an immune plasma-matched cohort from Papua New Guinea with our validated assay of merozoite phagocytosis. Highly correlated opsonization responses were observed across the 15 parasite strains tested, as were strong associations with protection (composite phagocytosis score across all strains in children uninfected at baseline: hazard ratio of 0.15, 95% confidence interval of 0.04 to 0.63). Opsonizing antibodies had a strong strain-transcending component, and the opsonization of transgenic parasites deficient for MSP3, MSP6, MSPDBL1, or P. falciparum MSP1-19 (PfMSP1-19) was similar to that of wild-type parasites. We have provided the first evidence that merozoite opsonization is predominantly strain transcending, and the highly consistent associations with protection against diverse parasite strains strongly supports the use of merozoite opsonization as a correlate of immunity for field studies and vaccine trials. These results demonstrate that conserved domains within merozoite antigens targeted by opsonization generate strain-transcending immune responses and represent promising vaccine candidates.
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16
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Boes A, Spiegel H, Kastilan R, Bethke S, Voepel N, Chudobová I, Bolscher JM, Dechering KJ, Fendel R, Buyel JF, Reimann A, Schillberg S, Fischer R. Analysis of the dose-dependent stage-specific in vitro efficacy of a multi-stage malaria vaccine candidate cocktail. Malar J 2016; 15:279. [PMID: 27188716 PMCID: PMC4869186 DOI: 10.1186/s12936-016-1328-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/04/2016] [Indexed: 12/17/2022] Open
Abstract
Background The high incidence and mortality rate of malaria remains a serious burden for many developing countries, and a vaccine that induces durable and highly effective immune responses is, therefore, desirable. An earlier analysis of the stage-specific in vitro efficacy of a malaria vaccine candidate cocktail (VAMAX) considered the general properties of complex multi-component, multi-stage combination vaccines in rabbit immunization experiments using a hyper-immunization protocol featuring six consecutive boosts and a strong, lipopolysaccharide-based adjuvant. This follow-up study investigates the effect of antigen dose on the in vitro efficacy of the malaria vaccine cocktail using a conventional vaccination scheme (one prime and two boosts) and a human-compatible adjuvant (Alhydrogel®). Results IgG purified from rabbits immunized with 0.1, 1, 10 or 50 µg doses of the VAMAX vaccine candidate cocktail was analysed for total IgG and antigen-cocktail-specific titers. An increase in cocktail-specific titers was observed between 0.1 and 1 µg and between 10 and 50 µg, whereas no significant difference in titers was observed between 1 and 10 µg. Antigen component-specific antibody titers and stage-specific in vitro efficacy assays were performed with pooled IgG from animals immunized with 1 and 50 µg of the VAMAX cocktail. Here, the component-specific antibody levels showed clear dose dependency whereas the determined stage-specific in vitro IC50 values (as a correlate of efficacy) were only dependent on the titer amounts of stage-specific antibodies. Conclusions The stage-specific in vitro efficacy of the VAMAX cocktail strongly correlates with the corresponding antigen-specific titers, which for their part depend on the antigen dose, but there is no indication that the dose has an effect on the in vitro efficacy of the induced antibodies. A comparison of these results with those obtained in the previous hyper-immunization study (where higher levels of antigen-specific IgG were observed) suggests that there is a significant need to induce an immune response matching efficacy requirements, especially for a PfAMA1-based blood stage vaccine, by using higher doses, better adjuvants and/or better formulations.
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Affiliation(s)
- Alexander Boes
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany.
| | - Robin Kastilan
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Susanne Bethke
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Nadja Voepel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Ivana Chudobová
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Judith M Bolscher
- TropIQ Health Science, Geert Grooteplein 28, Huispost 268, 6525, GA, Nijmegen, The Netherlands
| | - Koen J Dechering
- TropIQ Health Science, Geert Grooteplein 28, Huispost 268, 6525, GA, Nijmegen, The Netherlands
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany.,Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Johannes F Buyel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Stefan Schillberg
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany.,Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
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17
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Crosnier C, Iqbal Z, Knuepfer E, Maciuca S, Perrin AJ, Kamuyu G, Goulding D, Bustamante LY, Miles A, Moore SC, Dougan G, Holder AA, Kwiatkowski DP, Rayner JC, Pleass RJ, Wright GJ. Binding of Plasmodium falciparum Merozoite Surface Proteins DBLMSP and DBLMSP2 to Human Immunoglobulin M Is Conserved among Broadly Diverged Sequence Variants. J Biol Chem 2016; 291:14285-14299. [PMID: 27226583 PMCID: PMC4933183 DOI: 10.1074/jbc.m116.722074] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Indexed: 11/17/2022] Open
Abstract
Diversity at pathogen genetic loci can be driven by host adaptive immune selection pressure and may reveal proteins important for parasite biology. Population-based genome sequencing of Plasmodium falciparum, the parasite responsible for the most severe form of malaria, has highlighted two related polymorphic genes called dblmsp and dblmsp2, which encode Duffy binding-like (DBL) domain-containing proteins located on the merozoite surface but whose function remains unknown. Using recombinant proteins and transgenic parasites, we show that DBLMSP and DBLMSP2 directly and avidly bind human IgM via their DBL domains. We used whole genome sequence data from over 400 African and Asian P. falciparum isolates to show that dblmsp and dblmsp2 exhibit extreme protein polymorphism in their DBL domain, with multiple variants of two major allelic classes present in every population tested. Despite this variability, the IgM binding function was retained across diverse sequence representatives. Although this interaction did not seem to have an effect on the ability of the parasite to invade red blood cells, binding of DBLMSP and DBLMSP2 to IgM inhibited the overall immunoreactivity of these proteins to IgG from patients who had been exposed to the parasite. This suggests that IgM binding might mask these proteins from the host humoral immune system.
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Affiliation(s)
- Cécile Crosnier
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom; Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - Zamin Iqbal
- Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, United Kingdom
| | - Ellen Knuepfer
- Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, United Kingdom
| | - Sorina Maciuca
- Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, United Kingdom
| | - Abigail J Perrin
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom; Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - Gathoni Kamuyu
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - David Goulding
- Microbial Pathogenesis Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - Leyla Y Bustamante
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - Alistair Miles
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom; Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, United Kingdom
| | - Shona C Moore
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom; Warwick Systems Biology Centre, Senate House, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Gordon Dougan
- Microbial Pathogenesis Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - Anthony A Holder
- Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, United Kingdom
| | - Dominic P Kwiatkowski
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom; Wellcome Trust Centre for Human Genetics, Oxford OX3 7BN, United Kingdom
| | - Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom
| | - Richard J Pleass
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Gavin J Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom; Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, United Kingdom.
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18
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Beeson JG, Drew DR, Boyle MJ, Feng G, Fowkes FJI, Richards JS. Merozoite surface proteins in red blood cell invasion, immunity and vaccines against malaria. FEMS Microbiol Rev 2016; 40:343-72. [PMID: 26833236 PMCID: PMC4852283 DOI: 10.1093/femsre/fuw001] [Citation(s) in RCA: 218] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2016] [Indexed: 01/11/2023] Open
Abstract
Malaria accounts for an enormous burden of disease globally, with Plasmodium falciparum accounting for the majority of malaria, and P. vivax being a second important cause, especially in Asia, the Americas and the Pacific. During infection with Plasmodium spp., the merozoite form of the parasite invades red blood cells and replicates inside them. It is during the blood-stage of infection that malaria disease occurs and, therefore, understanding merozoite invasion, host immune responses to merozoite surface antigens, and targeting merozoite surface proteins and invasion ligands by novel vaccines and therapeutics have been important areas of research. Merozoite invasion involves multiple interactions and events, and substantial processing of merozoite surface proteins occurs before, during and after invasion. The merozoite surface is highly complex, presenting a multitude of antigens to the immune system. This complexity has proved challenging to our efforts to understand merozoite invasion and malaria immunity, and to developing merozoite antigens as malaria vaccines. In recent years, there has been major progress in this field, and several merozoite surface proteins show strong potential as malaria vaccines. Our current knowledge on this topic is reviewed, highlighting recent advances and research priorities. The authors summarize current knowledge of merozoite surface proteins of malaria parasites; their function in invasion, processing of surface proteins before, during and after invasion, their importance as targets of immunity, and the current status of malaria vaccines that target merozoite surface proteins.
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Affiliation(s)
- James G Beeson
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia Department of Microbiology, Monash University, Clayton, Victoria, Australia Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
| | - Damien R Drew
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia
| | - Michelle J Boyle
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia
| | - Gaoqian Feng
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia Department of Epidemiology and Preventive Medicine, Monash University, Clayton, Victoria, Australia School of Population Health, University of Melbourne, Parkville, Victoria, Australia
| | - Jack S Richards
- Burnet Institute for Medical Research and Public Health, 85 Commercial Road, Melbourne, Victoria, Australia Department of Microbiology, Monash University, Clayton, Victoria, Australia Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
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19
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Lin CS, Uboldi AD, Epp C, Bujard H, Tsuboi T, Czabotar PE, Cowman AF. Multiple Plasmodium falciparum Merozoite Surface Protein 1 Complexes Mediate Merozoite Binding to Human Erythrocytes. J Biol Chem 2016; 291:7703-15. [PMID: 26823464 DOI: 10.1074/jbc.m115.698282] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Indexed: 11/06/2022] Open
Abstract
Successful invasion of human erythrocytes byPlasmodium falciparummerozoites is required for infection of the host and parasite survival. The early stages of invasion are mediated via merozoite surface proteins that interact with human erythrocytes. The nature of these interactions are currently not well understood, but it is known that merozoite surface protein 1 (MSP1) is critical for successful erythrocyte invasion. Here we show that the peripheral merozoite surface proteins MSP3, MSP6, MSPDBL1, MSPDBL2, and MSP7 bind directly to MSP1, but independently of each other, to form multiple forms of the MSP1 complex on the parasite surface. These complexes have overlapping functions that interact directly with human erythrocytes. We also show that targeting the p83 fragment of MSP1 using inhibitory antibodies inhibits all forms of MSP1 complexes and disrupts parasite growthin vitro.
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Affiliation(s)
- Clara S Lin
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, the Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Alessandro D Uboldi
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Christian Epp
- the Department of Infectious Diseases, Parasitology, Universität Heidelberg, INF 324, 69120 Heidelberg, Germany
| | - Hermann Bujard
- the Zentrum für Molekulare Biologie der Universität Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany, and
| | - Takafumi Tsuboi
- the Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan
| | - Peter E Czabotar
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, the Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Alan F Cowman
- From the Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia, the Department of Medical Biology, University of Melbourne, Melbourne, Australia,
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20
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Pleass RJ, Moore SC, Stevenson L, Hviid L. Immunoglobulin M: Restrainer of Inflammation and Mediator of Immune Evasion by Plasmodium falciparum Malaria. Trends Parasitol 2015; 32:108-119. [PMID: 26597020 DOI: 10.1016/j.pt.2015.09.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/16/2015] [Accepted: 09/23/2015] [Indexed: 02/06/2023]
Abstract
Immunoglobulin M (IgM) is an ancient antibody class that is found in all vertebrates, with the exception of coelacanths, and is indispensable in both innate and adaptive immunity. The equally ancient human malaria parasite, Plasmodium falciparum, formed an intimate relationship with IgM with which it co-evolved. In this article, we discuss the association between IgM and human malaria parasites, building on several recent publications that implicate IgM as a crucial molecule that determines both host and parasite survival. Consequently, a better understanding of this association may lead to the development of improved intervention strategies.
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Affiliation(s)
- Richard J Pleass
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Shona C Moore
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK; Warwick Systems Biology Centre, Senate House, University of Warwick, Coventry, CV4 7AL, UK
| | - Liz Stevenson
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology, Department of Immunology and Microbiology (ISIM), Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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Chiu CYH, Hodder AN, Lin CS, Hill DL, Li Wai Suen CSN, Schofield L, Siba PM, Mueller I, Cowman AF, Hansen DS. Antibodies to the Plasmodium falciparum Proteins MSPDBL1 and MSPDBL2 Opsonize Merozoites, Inhibit Parasite Growth, and Predict Protection From Clinical Malaria. J Infect Dis 2015; 212:406-15. [PMID: 25646353 DOI: 10.1093/infdis/jiv057] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/15/2015] [Indexed: 11/13/2022] Open
Abstract
Increasing evidence suggests that antibodies against merozoite surface proteins (MSPs) play an important role in clinical immunity to malaria. Two unusual members of the MSP-3 family, merozoite surface protein duffy binding-like (MSPDBL)1 and MSPDBL2, have been shown to be extrinsically associated to MSP-1 on the parasite surface. In addition to a secreted polymorphic antigen associated with merozoite (SPAM) domain characteristic of MSP-3 family members, they also contain Duffy binding-like (DBL) domain and were found to bind to erythrocytes, suggesting that they play a role in parasite invasion. Antibody responses to these proteins were investigated in a treatment-reinfection study conducted in an endemic area of Papua New Guinea to determine their contribution to naturally acquired immunity. Antibodies to the SPAM domains of MSPDBL1 and MSPDBL2 as well as the DBL domain of MSPDBL1 were found to be associated with protection from Plasmodium falciparum clinical episodes. Moreover, affinity-purified anti-MSPDBL1 and MSPDBL2 were found to inhibit in vitro parasite growth and had strong merozoite opsonizing capacity, suggesting that protection targeting these antigens results from ≥2 distinct effector mechanisms. Together these results indicate that MSPDBL1 and MSPDBL2 are important targets of naturally acquired immunity and might constitute potential vaccine candidates.
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Affiliation(s)
- Chris Y H Chiu
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, University of Melbourne, Parkville, Victoria
| | - Anthony N Hodder
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, University of Melbourne, Parkville, Victoria
| | - Clara S Lin
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, University of Melbourne, Parkville, Victoria
| | - Danika L Hill
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, University of Melbourne, Parkville, Victoria
| | | | - Louis Schofield
- The Walter and Eliza Hall Institute of Medical Research Australian Institute of Tropical Health and Medicine, James Cook University, Douglas, Queensland, Australia
| | - Peter M Siba
- Vector Borne Disease Unit, Papua New Guinea Institute of Medical Research, Eastern Highlands Province, Goroka
| | - Ivo Mueller
- The Walter and Eliza Hall Institute of Medical Research Barcelona Center for International Health, University of Barcelona, Spain
| | - Alan F Cowman
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, University of Melbourne, Parkville, Victoria
| | - Diana S Hansen
- The Walter and Eliza Hall Institute of Medical Research Department of Medical Biology, University of Melbourne, Parkville, Victoria
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22
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The MSPDBL2 codon 591 polymorphism is associated with lumefantrine in vitro drug responses in Plasmodium falciparum isolates from Kilifi, Kenya. Antimicrob Agents Chemother 2014; 59:1770-5. [PMID: 25534732 PMCID: PMC4325780 DOI: 10.1128/aac.03522-14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms of drug resistance development in the Plasmodium falciparum parasite to lumefantrine (LUM), commonly used in combination with artemisinin, are still unclear. We assessed the polymorphisms of Pfmspdbl2 for associations with LUM activity in a Kenyan population. MSPDBL2 codon 591S was associated with reduced susceptibility to LUM (P = 0.04). The high frequency of Pfmspdbl2 codon 591S in Kenya may be driven by the widespread use of lumefantrine in artemisinin combination therapy (Coartem).
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23
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Osier FH, Mackinnon MJ, Crosnier C, Fegan G, Kamuyu G, Wanaguru M, Ogada E, McDade B, Rayner JC, Wright GJ, Marsh K. New antigens for a multicomponent blood-stage malaria vaccine. Sci Transl Med 2014; 6:247ra102. [PMID: 25080477 PMCID: PMC4856877 DOI: 10.1126/scitranslmed.3008705] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
An effective blood-stage vaccine against Plasmodium falciparum remains a research priority, but the number of antigens that have been translated into multicomponent vaccines for testing in clinical trials remains limited. Investigating the large number of potential targets found in the parasite proteome has been constrained by an inability to produce natively folded recombinant antigens for immunological studies. We overcame these constraints by generating a large library of biochemically active merozoite surface and secreted full-length ectodomain proteins. We then systematically examined the antibody reactivity against these proteins in a cohort of Kenyan children (n = 286) who were sampled at the start of a malaria transmission season and prospectively monitored for clinical episodes of malaria over the ensuing 6 months. We found that antibodies to previously untested or little-studied proteins had superior or equivalent potential protective efficacy to the handful of current leading malaria vaccine candidates. Moreover, cumulative responses to combinations comprising 5 of the 10 top-ranked antigens, including PF3D7_1136200, MSP2, RhopH3, P41, MSP11, MSP3, PF3D7_0606800, AMA1, Pf113, and MSRP1, were associated with 100% protection against clinical episodes of malaria. These data suggest not only that there are many more potential antigen candidates for the malaria vaccine development pipeline but also that effective vaccination may be achieved by combining a selection of these antigens.
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MESH Headings
- Age Factors
- Antibodies, Protozoan/blood
- Antigens, Protozoan/immunology
- Biomarkers/blood
- Child
- Child, Preschool
- Humans
- Infant
- Infant, Newborn
- Kenya/epidemiology
- Malaria Vaccines/immunology
- Malaria, Falciparum/blood
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Malaria, Falciparum/transmission
- Merozoites/immunology
- Peptide Fragments/immunology
- Plasmodium falciparum/immunology
- Prospective Studies
- Protozoan Proteins/immunology
- Seroepidemiologic Studies
- Time Factors
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Affiliation(s)
- Faith H Osier
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Margaret J Mackinnon
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Cécile Crosnier
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Gregory Fegan
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Gathoni Kamuyu
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Madushi Wanaguru
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Edna Ogada
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya
| | - Brian McDade
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK
| | - Julian C Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Gavin J Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK. Malaria Programme, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK
| | - Kevin Marsh
- Pathogen Vector and Human Biology Department, Kenya Medical Research Institute Centre for Geographical Medicine Research, Coast, P. O. Box 230, 80108 Kilifi, Kenya.
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24
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Lin CS, Uboldi AD, Marapana D, Czabotar PE, Epp C, Bujard H, Taylor NL, Perugini MA, Hodder AN, Cowman AF. The merozoite surface protein 1 complex is a platform for binding to human erythrocytes by Plasmodium falciparum. J Biol Chem 2014; 289:25655-69. [PMID: 25074930 DOI: 10.1074/jbc.m114.586495] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plasmodium falciparum is the causative agent of the most severe form of malaria in humans. The merozoite, an extracellular stage of the parasite lifecycle, invades erythrocytes in which they develop. The most abundant protein on the surface of merozoites is merozoite surface protein 1 (MSP1), which consists of four processed fragments. Studies indicate that MSP1 interacts with other peripheral merozoite surface proteins to form a large complex. Successful invasion of merozoites into host erythrocytes is dependent on this protein complex; however, the identity of all components and its function remain largely unknown. We have shown that the peripheral merozoite surface proteins MSPDBL1 and MSPDBL2 are part of the large MSP1 complex. Using surface plasmon resonance, we determined the binding affinities of MSPDBL1 and MSPDBL2 to MSP1 to be in the range of 2-4 × 10(-7) m. Both proteins bound to three of the four proteolytically cleaved fragments of MSP1 (p42, p38, and p83). In addition, MSPDBL1 and MSPDBL2, but not MSP1, bound directly to human erythrocytes. This demonstrates that the MSP1 complex acts as a platform for display of MSPDBL1 and MSPDBL2 on the merozoite surface for binding to receptors on the erythrocyte and invasion.
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Affiliation(s)
- Clara S Lin
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia
| | - Alessandro D Uboldi
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia
| | - Danushka Marapana
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia
| | - Peter E Czabotar
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia
| | - Christian Epp
- Department of Infectious Diseases, Parasitology, Universität Heidelberg, INF 324, D-69120 Heidelberg, Germany
| | - Hermann Bujard
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), INF 282, D-69120 Heidelberg, Germany, and
| | - Nicole L Taylor
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3082, Australia
| | - Matthew A Perugini
- Department of Biochemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne 3082, Australia
| | - Anthony N Hodder
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia,
| | - Alan F Cowman
- From the The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia, Department of Medical Biology, The University of Melbourne, Melbourne 3010, Australia,
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25
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The origin and diversification of the merozoite surface protein 3 (msp3) multi-gene family in Plasmodium vivax and related parasites. Mol Phylogenet Evol 2014; 78:172-84. [PMID: 24862221 DOI: 10.1016/j.ympev.2014.05.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 05/02/2014] [Accepted: 05/07/2014] [Indexed: 11/22/2022]
Abstract
The genus Plasmodium is a diversified group of parasites with more than 200 known species that includes those causing malaria in humans. These parasites use numerous proteins in a complex process that allows them to invade the red blood cells of their vertebrate hosts. Many of those proteins are part of multi-gene families; one of which is the merozoite surface protein-3 (msp3) family. The msp3 multi-gene family is considered important in the two main human parasites, Plasmodium vivax and Plasmodium falciparum, as its paralogs are simultaneously expressed in the blood stage (merozoite) and are immunogenic. There are large differences among Plasmodium species in the number of paralogs in this family. Such differences have been previously explained, in part, as adaptations that allow the different Plasmodium species to invade their hosts. To investigate this, we characterized the array containing msp3 genes among several Plasmodium species, including P. falciparum and P. vivax. We first found no evidence indicating that the msp3 family of P. falciparum was homologous to that of P. vivax. Subsequently, by focusing on the diverse clade of nonhuman primate parasites to which P. vivax is closely related, where homology was evident, we found no evidence indicating that the interspecies variation in the number of paralogs was an adaptation related to changes in host range or host switches. Overall, we hypothesize that the evolution of the msp3 family in P. vivax is consistent with a model of multi-allelic diversifying selection where the paralogs may have functionally redundant roles in terms of increasing antigenic diversity. Thus, we suggest that the expressed MSP3 proteins could serve as "decoys", via antigenic diversity, during the critical process of invading the host red blood cells.
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26
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Zenonos ZA, Rayner JC, Wright GJ. Towards a comprehensive Plasmodium falciparum merozoite cell surface and secreted recombinant protein library. Malar J 2014; 13:93. [PMID: 24620899 PMCID: PMC3995786 DOI: 10.1186/1475-2875-13-93] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 03/07/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum is the aetiological agent for malaria, a deadly infectious disease for which no vaccine has yet been licensed. The proteins displayed on the merozoite cell surface have long been considered attractive vaccine targets because of their direct exposure to host antibodies; however, progress in understanding the functional role of these targets has been hindered by technical challenges associated with expressing these proteins in a functionally active recombinant form. To address this, a method that enables the systematic expression of functional extracellular Plasmodium proteins was previously developed, and used to create a library of 42 merozoite proteins. METHODS To compile a more comprehensive library of recombinant proteins representing the repertoire of P. falciparum merozoite extracellular proteins for systematic vaccine and functional studies, genome-wide expression profiling was used to identify additional candidates. Candidate proteins were recombinantly produced and their integrity and expression levels were tested by Western blotting and ELISA. RESULTS Twenty-five additional genes that were upregulated during late schizogony, and predicted to encode secreted and cell surface proteins, were identified and expressed as soluble recombinant proteins. A band consistent with the entire ectodomain was observed by immunoblotting for the majority of the proteins and their expression levels were quantified. By using sera from malaria-exposed immune adults, the immunoreactivity of 20 recombinant proteins was assessed, and most of the merozoite ligands were found to carry heat-labile epitopes. To facilitate systematic comparative studies across the entire library, multiple Plasmodium proteins were simultaneously purified using a custom-made platform. CONCLUSIONS A library of recombinant P. falciparum secreted and cell surface proteins was expanded by 20 additional proteins, which were shown to express at usable levels and contain conformational epitopes. This resource of extracellular P. falciparum merozoite proteins, which now contains 62 full-length ectodomains, will be a valuable tool in elucidating the function of these proteins during the blood stages of infection, and facilitate the comparative assessment of blood stage vaccine candidates.
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Affiliation(s)
| | | | - Gavin J Wright
- Cell Surface Signalling Laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1SA, UK.
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27
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Crosnier C, Wanaguru M, McDade B, Osier FH, Marsh K, Rayner JC, Wright GJ. A library of functional recombinant cell-surface and secreted P. falciparum merozoite proteins. Mol Cell Proteomics 2013; 12:3976-86. [PMID: 24043421 PMCID: PMC3861738 DOI: 10.1074/mcp.o113.028357] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Malaria, an infectious disease caused by parasites of the Plasmodium genus, is one of the world's major public health concerns causing up to a million deaths annually, mostly because of P. falciparum infections. All of the clinical symptoms are associated with the blood stage of the disease, an obligate part of the parasite life cycle, when a form of the parasite called the merozoite recognizes and invades host erythrocytes. During erythrocyte invasion, merozoites are directly exposed to the host humoral immune system making the blood stage of the parasite a conceptually attractive therapeutic target. Progress in the functional and molecular characterization of P. falciparum merozoite proteins, however, has been hampered by the technical challenges associated with expressing these proteins in a biochemically active recombinant form. This challenge is particularly acute for extracellular proteins, which are the likely targets of host antibody responses, because they contain structurally critical post-translational modifications that are not added by some recombinant expression systems. Here, we report the development of a method that uses a mammalian expression system to compile a protein resource containing the entire ectodomains of 42 P. falciparum merozoite secreted and cell surface proteins, many of which have not previously been characterized. Importantly, we are able to recapitulate known biochemical activities by showing that recombinant MSP1-MSP7 and P12-P41 directly interact, and that both recombinant EBA175 and EBA140 can bind human erythrocytes in a sialic acid-dependent manner. Finally, we use sera from malaria-exposed immune adults to profile the relative immunoreactivity of the proteins and show that the majority of the antigens contain conformational (heat-labile) epitopes. We envisage that this resource of recombinant proteins will make a valuable contribution toward a molecular understanding of the blood stage of P. falciparum infections and facilitate the comparative screening of antigens as blood-stage vaccine candidates.
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Affiliation(s)
- Cécile Crosnier
- Cell Surface Signalling laboratory, Wellcome Trust Sanger Institute, Cambridge CB10 1HH, UK
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Analysis of antibodies to newly described Plasmodium falciparum merozoite antigens supports MSPDBL2 as a predicted target of naturally acquired immunity. Infect Immun 2013; 81:3835-42. [PMID: 23897617 PMCID: PMC3811751 DOI: 10.1128/iai.00301-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Prospective studies continue to identify malaria parasite genes with particular patterns of polymorphism which indicate they may be under immune selection, and the encoded proteins require investigation. Sixteen new recombinant protein reagents were designed to characterize three such polymorphic proteins expressed in Plasmodium falciparum schizonts and merozoites: MSPDBL1 (also termed MSP3.4) and MSPDBL2 (MSP3.8), which possess Duffy binding-like (DBL) domains, and SURFIN4.2, encoded by a member of the surface-associated interspersed (surf) multigene family. After testing the antigenicities of these reagents by murine immunization and parasite immunofluorescence, we analyzed naturally acquired antibody responses to the antigens in two cohorts in coastal Kenya in which the parasite was endemic (Chonyi [n = 497] and Ngerenya [n = 461]). As expected, the prevalence and levels of serum antibodies increased with age. We then investigated correlations with subsequent risk of clinical malaria among children <11 years of age during 6 months follow-up surveillance. Antibodies to the polymorphic central region of MSPDBL2 were associated with reduced risk of malaria in both cohorts, with statistical significance remaining for the 3D7 allelic type after adjustment for individuals' ages in years and antibody reactivity to whole-schizont extract (Chonyi, risk ratio, 0.51, and 95% confidence interval [CI], 0.28 to 0.93; Ngerenya, risk ratio, 0.38, and 95% CI, 0.18 to 0.82). For the MSPDBL1 Palo Alto allelic-type antigen, there was a protective association in one cohort (Ngerenya, risk ratio, 0.53, and 95% CI, 0.32 to 0.89), whereas the other antigens showed no protective associations after adjustment. These findings support the prediction that antibodies to the polymorphic region of MSPDBL2 contribute to protective immunity.
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Plasmodium vivax merozoite surface protein-3 (PvMSP3): expression of an 11 member multigene family in blood-stage parasites. PLoS One 2013; 8:e63888. [PMID: 23717506 PMCID: PMC3662707 DOI: 10.1371/journal.pone.0063888] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Accepted: 04/07/2013] [Indexed: 02/02/2023] Open
Abstract
Background Three members of the Plasmodium vivax merozoite surface protein-3 (PvMSP3) family (PvMSP3-α, PvMSP3-β and PvMSP3-γ) were initially characterized and later shown to be part of a larger highly diverse family, encoded by a cluster of genes arranged head-to-tail in chromosome 10. PvMSP3-α and PvMSP3-β have become genetic markers in epidemiological studies, and are being evaluated as vaccine candidates. This research investigates the gene and protein expression of the entire family and pertinent implications. Methodology/Principal Findings A 60 kb multigene locus from chromosome 10 in P. vivax (Salvador 1 strain) was studied to classify the number of pvmsp3 genes present, and compare their transcription, translation and protein localization patterns during blood-stage development. Eleven pvmsp3 paralogs encode an N-terminal NLRNG signature motif, a central domain containing repeated variable heptad sequences, and conserved hydrophilic C-terminal features. One additional ORF in the locus lacks these features and was excluded as a member of the family. Transcripts representing all eleven pvmsp3 genes were detected in trophozoite- and schizont-stage RNA. Quantitative immunoblots using schizont-stage extracts and antibodies specific for each PvMSP3 protein demonstrated that all but PvMSP3.11 could be detected. Homologs were also detected by immunoblot in the closely related simian species, P. cynomolgi and P. knowlesi. Immunofluorescence assays confirmed that eight of the PvMSP3s are present in mature schizonts. Uniquely, PvMSP3.7 was expressed exclusively at the apical end of merozoites. Conclusion/Significance Specific proteins were detected representing the expression of 10 out of 11 genes confirmed as members of the pvmsp3 family. Eight PvMSP3s were visualized surrounding merozoites. In contrast, PvMSP3.7 was detected at the apical end of the merozoites. Pvmsp3.11 transcripts were present, though no corresponding protein was detected. PvMSP3 functions remain unknown. The ten expressed PvMSP3s are predicted to have unique and complementary functions in merozoite biology.
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Modulation of PF10_0355 (MSPDBL2) alters Plasmodium falciparum response to antimalarial drugs. Antimicrob Agents Chemother 2013; 57:2937-41. [PMID: 23587962 DOI: 10.1128/aac.02574-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria's ability to rapidly adapt to new drugs has allowed it to remain one of the most devastating infectious diseases of humans. Understanding and tracking the genetic basis of these adaptations are critical to the success of treatment and intervention strategies. The novel antimalarial resistance locus PF10_0355 (Pfmspdbl2) was previously associated with the parasite response to halofantrine, and functional validation confirmed that overexpression of this gene lowered parasite sensitivity to both halofantrine and the structurally related antimalarials mefloquine and lumefantrine, predominantly through copy number variation. Here we further characterize the role of Pfmspdbl2 in mediating the antimalarial drug response of Plasmodium falciparum. Knockout of Pfmspdbl2 increased parasite sensitivity to halofantrine, mefloquine, and lumefantrine but not to unrelated antimalarials, further suggesting that this gene mediates the parasite response to a specific class of antimalarial drugs. A single nucleotide polymorphism encoding a C591S mutation within Pfmspdbl2 had the strongest association with halofantrine sensitivity and showed a high derived allele frequency among Senegalese parasites. Transgenic parasites expressing the ancestral Pfmspdbl2 allele were more sensitive to halofantrine and structurally related antimalarials than were parasites expressing the derived allele, revealing an allele-specific effect on drug sensitivity in the absence of copy number effects. Finally, growth competition experiments showed that under drug pressure, parasites expressing the derived allele of Pfmspdbl2 outcompeted parasites expressing the ancestral allele within a few generations. Together, these experiments demonstrate that modulation of Pfmspdbl2 affects malaria parasite responses to antimalarial drugs.
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Mueller I, Galinski MR, Tsuboi T, Arevalo-Herrera M, Collins WE, King CL. Natural acquisition of immunity to Plasmodium vivax: epidemiological observations and potential targets. ADVANCES IN PARASITOLOGY 2013; 81:77-131. [PMID: 23384622 DOI: 10.1016/b978-0-12-407826-0.00003-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Population studies show that individuals acquire immunity to Plasmodium vivax more quickly than Plasmodium falciparum irrespective of overall transmission intensity, resulting in the peak burden of P. vivax malaria in younger age groups. Similarly, actively induced P. vivax infections in malaria therapy patients resulted in faster and generally more strain-transcending acquisition of immunity than P. falciparum infections. The mechanisms behind the more rapid acquisition of immunity to P. vivax are poorly understood. Natural acquired immune responses to P. vivax target both pre-erythrocytic and blood-stage antigens and include humoral and cellular components. To date, only a few studies have investigated the association of these immune responses with protection, with most studies focussing on a few merozoite antigens (such as the Pv Duffy binding protein (PvDBP), the Pv reticulocyte binding proteins (PvRBPs), or the Pv merozoite surface proteins (PvMSP1, 3 & 9)) or the circumsporozoite protein (PvCSP). Naturally acquired transmission-blocking (TB) immunity (TBI) was also found in several populations. Although limited, these data support the premise that developing a multi-stage P. vivax vaccine may be feasible and is worth pursuing.
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Affiliation(s)
- Ivo Mueller
- Walter + Eliza Hall Institute, Infection & Immunity Division, Parkville, Victoria, Australia
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Antigenicity and immunogenicity of Plasmodium vivax merozoite surface protein-3. PLoS One 2013; 8:e56061. [PMID: 23457498 PMCID: PMC3573074 DOI: 10.1371/journal.pone.0056061] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/04/2013] [Indexed: 11/19/2022] Open
Abstract
A recent clinical trial in African children demonstrated the potential utility of merozoite surface protein (MSP)-3 as a vaccine against Plasmodium falciparum malaria. The present study evaluated the use of Plasmodium vivax MSP-3 (PvMSP-3) as a target antigen in vaccine formulations against malaria caused by P. vivax. Recombinant proteins representing MSP-3α and MSP-3β of P. vivax were expressed as soluble histidine-tagged bacterial fusions. Antigenicity during natural infection was evaluated by detecting specific antibodies using sera from individuals living in endemic areas of Brazil. A large proportion of infected individuals presented IgG antibodies to PvMSP-3α (68.2%) and at least 1 recombinant protein representing PvMSP-3β (79.1%). In spite of the large responder frequency, reactivity to both antigens was significantly lower than was observed for the immunodominant epitope present on the 19-kDa C-terminal region of PvMSP-1. Immunogenicity of the recombinant proteins was studied in mice in the absence or presence of different adjuvant formulations. PvMSP-3β, but not PvMSP-3α, induced a TLR4-independent humoral immune response in the absence of any adjuvant formulation. The immunogenicity of the recombinant antigens were also tested in formulations containing different adjuvants (Alum, Salmonella enterica flagellin, CpG, Quil A,TiterMax® and incomplete Freunds adjuvant) and combinations of two adjuvants (Alum plus flagellin, and CpG plus flagellin). Recombinant PvMSP-3α and PvMSP-3β elicited higher antibody titers capable of recognizing P. vivax-infected erythrocytes harvested from malaria patients. Our results confirm that P. vivax MSP-3 antigens are immunogenic during natural infection, and the corresponding recombinant proteins may be useful in elucidating their vaccine potential.
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Muellenbeck MF, Ueberheide B, Amulic B, Epp A, Fenyo D, Busse CE, Esen M, Theisen M, Mordmüller B, Wardemann H. Atypical and classical memory B cells produce Plasmodium falciparum neutralizing antibodies. ACTA ACUST UNITED AC 2013; 210:389-99. [PMID: 23319701 PMCID: PMC3570107 DOI: 10.1084/jem.20121970] [Citation(s) in RCA: 157] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Plasmodium falciparum infection leads to the development of protective classical and atypical memory B cell antibody responses. Antibodies can protect from Plasmodium falciparum (Pf) infection and clinical malaria disease. However, in the absence of constant reexposure, serum immunoglobulin (Ig) levels rapidly decline and full protection from clinical symptoms is lost, suggesting that B cell memory is functionally impaired. We show at the single cell level that natural Pf infection induces the development of classical memory B cells (CM) and atypical memory B cells (AtM) that produce broadly neutralizing antibodies against blood stage Pf parasites. CM and AtM contribute to anti-Pf serum IgG production, but only AtM show signs of active antibody secretion. AtM and CM were also different in their IgG gene repertoire, suggesting that they develop from different precursors. The findings provide direct evidence that natural Pf infection leads to the development of protective memory B cell antibody responses and suggest that constant immune activation rather than impaired memory function leads to the accumulation of AtM in malaria. Understanding the memory B cell response to natural Pf infection may be key to the development of a malaria vaccine that induces long-lived protection.
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Affiliation(s)
- Matthias F Muellenbeck
- Max Planck Research Group Molecular Immunology, Max Planck Institute for Infection Biology, 10117 Berlin, Germany
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Fan YT, Wang Y, Ju C, Zhang T, Xu B, Hu W, Chen JH. Systematic analysis of natural antibody responses to P. falciparum merozoite antigens by protein arrays. J Proteomics 2013. [DOI: 10.1016/j.jprot.2012.11.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Efficient measurement of opsonising antibodies to Plasmodium falciparum merozoites. PLoS One 2012; 7:e51692. [PMID: 23300556 PMCID: PMC3530572 DOI: 10.1371/journal.pone.0051692] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 11/05/2012] [Indexed: 12/03/2022] Open
Abstract
Background Antibodies targeting merozoites are important in protection from malaria. Therefore, merozoite surface proteins are attractive vaccine candidates. There is a need for robust functional assays to investigate mechanisms of acquired immunity and vaccine efficacy. To date, the study of merozoite phagocytosis has been confounded by the complexity and variability of in vitro assays. Methodology/Principal findings We have developed a new flow cytometry-based merozoite phagocytosis assay. An optimized merozoite preparation technique produced high yields of merozoites separated from haemozoin. Phagocytosis by the undifferentiated THP-1 monocytic cell line was mediated only by Fc Receptors, and was therefore ideal for studying opsonising antibody responses. The assay showed robust phagocytosis with highly diluted immune sera and strong inter-assay correlation. The assay effectively measured differences in opsonisation-dependent phagocytosis among individuals. Conclusions/Significance This highly reproducible assay has potential applications in assessing the role of opsonic phagocytosis in naturally acquired immunity and vaccine trials.
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Amambua-Ngwa A, Tetteh KKA, Manske M, Gomez-Escobar N, Stewart LB, Deerhake ME, Cheeseman IH, Newbold CI, Holder AA, Knuepfer E, Janha O, Jallow M, Campino S, MacInnis B, Kwiatkowski DP, Conway DJ. Population genomic scan for candidate signatures of balancing selection to guide antigen characterization in malaria parasites. PLoS Genet 2012; 8:e1002992. [PMID: 23133397 PMCID: PMC3486833 DOI: 10.1371/journal.pgen.1002992] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 08/13/2012] [Indexed: 11/19/2022] Open
Abstract
Acquired immunity in vertebrates maintains polymorphisms in endemic pathogens, leading to identifiable signatures of balancing selection. To comprehensively survey for genes under such selection in the human malaria parasite Plasmodium falciparum, we generated paired-end short-read sequences of parasites in clinical isolates from an endemic Gambian population, which were mapped to the 3D7 strain reference genome to yield high-quality genome-wide coding sequence data for 65 isolates. A minority of genes did not map reliably, including the hypervariable var, rifin, and stevor families, but 5,056 genes (90.9% of all in the genome) had >70% sequence coverage with minimum read depth of 5 for at least 50 isolates, of which 2,853 genes contained 3 or more single nucleotide polymorphisms (SNPs) for analysis of polymorphic site frequency spectra. Against an overall background of negatively skewed frequencies, as expected from historical population expansion combined with purifying selection, the outlying minority of genes with signatures indicating exceptionally intermediate frequencies were identified. Comparing genes with different stage-specificity, such signatures were most common in those with peak expression at the merozoite stage that invades erythrocytes. Members of clag, PfMC-2TM, surfin, and msp3-like gene families were highly represented, the strongest signature being in the msp3-like gene PF10_0355. Analysis of msp3-like transcripts in 45 clinical and 11 laboratory adapted isolates grown to merozoite-containing schizont stages revealed surprisingly low expression of PF10_0355. In diverse clonal parasite lines the protein product was expressed in a minority of mature schizonts (<1% in most lines and ∼10% in clone HB3), and eight sub-clones of HB3 cultured separately had an intermediate spectrum of positive frequencies (0.9 to 7.5%), indicating phase variable expression of this polymorphic antigen. This and other identified targets of balancing selection are now prioritized for functional study.
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Affiliation(s)
| | - Kevin K. A. Tetteh
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Magnus Manske
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | | | - Lindsay B. Stewart
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - M. Elizabeth Deerhake
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Ian H. Cheeseman
- Medical Research Council Unit, Fajara, Banjul, The Gambia
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Christopher I. Newbold
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
| | - Anthony A. Holder
- Division of Parasitology, MRC National Institute for Medical Research, London, United Kingdom
| | - Ellen Knuepfer
- Division of Parasitology, MRC National Institute for Medical Research, London, United Kingdom
| | - Omar Janha
- Medical Research Council Unit, Fajara, Banjul, The Gambia
| | | | - Susana Campino
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | | | - Dominic P. Kwiatkowski
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - David J. Conway
- Medical Research Council Unit, Fajara, Banjul, The Gambia
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- * E-mail:
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Petrova GV, Gorski J. Cross-reactive responses to modified M1₅₈-₆₆ peptides by CD8⁺ T cells that use noncanonical BV genes can describe unknown repertoires. Eur J Immunol 2012; 42:3001-8. [PMID: 22865108 DOI: 10.1002/eji.201242596] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 06/21/2012] [Accepted: 07/30/2012] [Indexed: 11/06/2022]
Abstract
Memory T-cell repertoires are populated by clonotypes selected by an individual's history of antigen exposures. Our previous analysis of middle-age CD8(+) T-cell memory repertoires to the influenza-derived epitope M1(58-66) , described a network of highly cross-reactive BV19 clonotypes responding to M1(58-66) and at least one peptide with a conservative amino acid substitution at either of two TCR contact positions. Here, we report that some substitutions abrogate BV19 responses and favor responses with different BV. Cross-reactive T cells using seven other BV families responded to 12 of 13 peptides tested. BV12 clonotypes define the most extensive cross-reactive network that encompasses seven peptides. We generated 3D networks based on the peptides recognized and BV family used and observed a cluster of five peptides that includes M1(58-66) and another cluster of five peptides that does not include M1(58-66) . The first cluster represents peptides structurally similar to M1(58-66) , and the second represents peptides with more considerable changes in epitope recognition surface. We hypothesize that the second cluster represents the cross-reactive network around another unknown epitope or epitopes. This data supports a model of stable CD8(+) T-cell memory networks that include a substantial contribution from cross-reactive T cells.
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Affiliation(s)
- Galina V Petrova
- The Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226, USA
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Paziewska A, Siński E, Harris PD. Recombination, diversity and allele sharing of infectivity proteins between Bartonella species from rodents. MICROBIAL ECOLOGY 2012; 64:525-536. [PMID: 22419104 PMCID: PMC3391547 DOI: 10.1007/s00248-012-0033-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 02/23/2012] [Indexed: 05/31/2023]
Abstract
The alpha-Proteobacterium Bartonella is a common parasite of voles and mice, giving rise to short-lived (4 weeks to 2 months) infections. Here, we report high sequence diversity in genes of the VirB/VirD type IV secretion system (T4SS), amongst Bartonella from natural rodent populations in NE Poland. The VirB5 protein is predicted to consist of three conserved alpha helices separated by loops of variable length which include numerous indels. The C-terminal domain includes repeat stretches of KEK residues, reflecting underlying homopolymeric stretches of adenine residues. A total of 16 variants of VirB5, associated with host identity, but not bacterial taxon, were identified from 22 Bartonella isolates. One was clearly a recombinant from two others, another included an insertion of two KEK repeats. The virB5 gene appears to evolve via both mutation and recombination, as well as slippage mediated insertion/deletion events. The recombinational units are thought to be relatively short, as there was no evidence of linkage disequilibrium between virB5 and the bepA locus only 5.5 kb distant. The diversity of virB5 is assumed to be related to immunological role of this protein in Bartonella infections; diversity of virB5 may assist persistence of Bartonella in the rodent population, despite the relatively short (3-4 weeks) duration of individual infections. It is clear from the distribution of virB5 and bepA alleles that recombination within and between clades is widespread, and frequently crosses the boundaries of conventionally recognised Bartonella species.
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Affiliation(s)
- Anna Paziewska
- National Centre for Biosystematics, Natural History Museum, University of Oslo, PO Box 1172, Blindern, Oslo, Norway.
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Hodder AN, Czabotar PE, Uboldi AD, Clarke OB, Lin CS, Healer J, Smith BJ, Cowman AF. Insights into Duffy binding-like domains through the crystal structure and function of the merozoite surface protein MSPDBL2 from Plasmodium falciparum. J Biol Chem 2012; 287:32922-39. [PMID: 22843685 DOI: 10.1074/jbc.m112.350504] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Invasion of human red blood cells by Plasmodium falciparum involves interaction of the merozoite form through proteins on the surface coat. The erythrocyte binding-like protein family functions after initial merozoite interaction by binding via the Duffy binding-like (DBL) domain to receptors on the host red blood cell. The merozoite surface proteins DBL1 and -2 (PfMSPDBL1 and PfMSPDBL2) (PF10_0348 and PF10_0355) are extrinsically associated with the merozoite, and both have a DBL domain in each protein. We expressed and refolded recombinant DBL domains for PfMSPDBL1 and -2 and show they are functional. The red cell binding characteristics of these domains were shown to be similar to full-length forms of these proteins isolated from parasite cultures. Futhermore, metal cofactors were found to enhance the binding of both the DBL domains and the parasite-derived full-length proteins to erythrocytes, which has implications for receptor binding of other DBL-containing proteins in Plasmodium spp. We solved the structure of the erythrocyte-binding DBL domain of PfMSPDBL2 to 2.09 Å resolution and modeled that of PfMSPDBL1, revealing a canonical DBL fold consisting of a boomerang shaped α-helical core formed from three subdomains. PfMSPDBL2 is highly polymorphic, and mapping of these mutations shows they are on the surface, predominantly in the first two domains. For both PfMSPDBL proteins, polymorphic variation spares the cleft separating domains 1 and 2 from domain 3, and the groove between the two major helices of domain 3 extends beyond the cleft, indicating these regions are functionally important and are likely to be associated with the binding of a receptor on the red blood cell.
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Affiliation(s)
- Anthony N Hodder
- The Walter and Eliza Hall Institute of Medical Research, Melbourne 3052, Australia.
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40
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Mourão LC, Morais CG, Bueno LL, Jimenez MC, Soares IS, Fontes CJ, Guimarães Lacerda MV, Xavier MS, Barnwell JW, Galinski MR, Braga EM. Naturally acquired antibodies to Plasmodium vivax blood-stage vaccine candidates (PvMSP-1₁₉ and PvMSP-3α₃₅₉₋₇₉₈ and their relationship with hematological features in malaria patients from the Brazilian Amazon. Microbes Infect 2012; 14:730-9. [PMID: 22445906 DOI: 10.1016/j.micinf.2012.02.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 02/28/2012] [Accepted: 02/29/2012] [Indexed: 01/22/2023]
Abstract
An important step when designing a vaccine is identifying the antigens that function as targets of naturally acquired antibodies. We investigated specific antibody responses against two Plasmodium vivax vaccine candidates, PvMSP-1₁₉ and PvMSP-3α₃₅₉₋₇₉₈. Moreover, we assessed the relationship between these antibodies and morbidity parameters. PvMSP-1₁₉ was the most immunogenic antigen and the frequency of responders to this protein tended to increase in P. vivax patients with higher parasitemia. For both antigens, IgG antibody responses tended to be lower in patients who had experienced their first bout of malaria. Furthermore, anemic patients presented higher IgG antibody responses to PvMSP-3α₃₅₉₋₇₉₈. Since the humoral response involves a number of antibodies acting simultaneously on different targets, we performed a Principal Component Analysis (PCA). Anemic patients had, on average, higher first principal component scores (IgG1/IgG2/IgG3/IgG4 anti-MSP3α), which were negatively correlated with hemoglobin levels. Since antibodies against PfMSP-3 have been strongly associated with clinical protection, we cannot exclude the possibility of a dual role of PvMSP-3 specific antibodies in both immunity and pathogenesis of vivax malaria. Our results confirm the high immunogenicity of the conserved C terminus of PvMSP-1 and points to the considerable immunogenicity of polymorphic PvMSP-3α₃₅₉₋₇₉₈ during natural infection.
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Affiliation(s)
- Luiza Carvalho Mourão
- Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, 31270-901 Belo Horizonte, Brazil
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Sakamoto H, Takeo S, Maier AG, Sattabongkot J, Cowman AF, Tsuboi T. Antibodies against a Plasmodium falciparum antigen PfMSPDBL1 inhibit merozoite invasion into human erythrocytes. Vaccine 2012; 30:1972-80. [PMID: 22248820 DOI: 10.1016/j.vaccine.2012.01.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 01/04/2012] [Accepted: 01/05/2012] [Indexed: 11/27/2022]
Abstract
One approach to develop a malaria blood-stage vaccine is to target proteins that play critical roles in the erythrocyte invasion of merozoites. The merozoite surface proteins (MSPs) and the erythrocyte-binding antigens (EBAs) are considered promising vaccine candidates, for they are known to play important roles in erythrocyte invasion and are exposed to host immune system. Here we focused on a Plasmodium falciparum antigen, PfMSPDBL1 (encoded by PF10_0348 gene) that is a member of the MSP3 family and has both Duffy binding-like (DBL) domain and secreted polymorphic antigen associated with merozoites (SPAM) domain. Therefore, we aimed to characterize PfMSPDBL1 as a vaccine candidate. Recombinant full-length protein (rFL) of PfMSPDBL1 was synthesized by a wheat germ cell-free system, and rabbit antiserum was raised against rFL. We show that rabbit anti-PfMSPDBL1 antibodies inhibited erythrocyte invasion of wild type parasites in vitro in a dose dependent manner, and the specificity of inhibitory activity was confirmed using PfMSPDBL1 knockout parasites. Pre-incubation of the anti-PfMSPDBL1 antibodies with the recombinant SPAM domain had no effect on the inhibitory activity suggesting that antibodies to this region were not involved. In addition, antibodies to rFL were elicited by P. falciparum infection in malaria endemic area, suggesting the PfMSLDBL1 is immunogenic to humans. Our results suggest that PfMSPDBL1 is a novel blood-stage malaria vaccine candidate.
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Affiliation(s)
- Hirokazu Sakamoto
- Cell-Free Science and Technology Research Center and Ehime University, Matsuyama, Ehime 790-8577, Japan
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Bang G, Prieur E, Roussilhon C, Druilhe P. Pre-clinical assessment of novel multivalent MSP3 malaria vaccine constructs. PLoS One 2011; 6:e28165. [PMID: 22145028 PMCID: PMC3228738 DOI: 10.1371/journal.pone.0028165] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Accepted: 11/02/2011] [Indexed: 11/18/2022] Open
Abstract
Background MSP3 has been shown to induce protection against malaria in African children. The characterization of a family of Plasmodium falciparum merozoite surface protein 3 (MSP3) antigens sharing a similar structural organization, simultaneously expressed on the merozoite surface and targeted by a cross-reactive network of protective antibodies, is intriguing and offers new perspectives for the development of subunit vaccines against malaria. Methods Eight recombinant polyproteins containing carefully selected regions of this family covalently linked in different combinations were all efficiently produced in Escherichia coli. The polyproteins consisted of one monovalent, one bivalent, one trivalent, two tetravalents, one hexavalent construct, and two tetravalents incorporating coiled-coil repeats regions from LSA3 and p27 vaccine candidates. Results All eight polyproteins induced a strong and homogeneous antibody response in mice of three distinct genotypes, with a dominance of cytophilic IgG subclasses, lasting up to six months after the last immunization. Vaccine-induced antibodies exerted a strong monocyte-mediated in vitro inhibition of P. falciparum growth. Naturally acquired antibodies from individuals living in an endemic area of Senegal recognized the polyproteins with a reactivity mainly constituted of cytophilic IgG subclasses. Conclusions Combination of genetically conserved and antigenically related MSP3 proteins provides promising subunit vaccine constructs, with improved features as compared to the first generation construct employed in clinical trials (MSP3-LSP). These multivalent MSP3 vaccine constructs expand the epitope display of MSP3 family proteins, and lead to the efficient induction of a wider range of antibody subclasses, even in genetically different mice. These findings are promising for future immunization of genetically diverse human populations.
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MESH Headings
- Adolescent
- Animals
- Antibodies, Protozoan/immunology
- Antibodies, Protozoan/metabolism
- Antibody Formation/immunology
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Blotting, Western
- Child
- Child, Preschool
- Cross Reactions
- Drug Evaluation, Preclinical
- Enzyme-Linked Immunosorbent Assay
- Female
- Flow Cytometry
- Fluorescent Antibody Technique
- Humans
- Immunization
- Immunoglobulin G/immunology
- Infant
- Malaria Vaccines/genetics
- Malaria Vaccines/immunology
- Malaria Vaccines/therapeutic use
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Plasmodium falciparum/genetics
- Plasmodium falciparum/immunology
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
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Affiliation(s)
- Gilles Bang
- Malaria Vaccine Development Laboratory, Institut Pasteur, and Vac4all initiative, Paris, France
| | - Eric Prieur
- Malaria Vaccine Development Laboratory, Institut Pasteur, and Vac4all initiative, Paris, France
| | - Christian Roussilhon
- Malaria Vaccine Development Laboratory, Institut Pasteur, and Vac4all initiative, Paris, France
| | - Pierre Druilhe
- Malaria Vaccine Development Laboratory, Institut Pasteur, and Vac4all initiative, Paris, France
- * E-mail:
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Bélard S, Issifou S, Hounkpatin AB, Schaumburg F, Ngoa UA, Esen M, Fendel R, de Salazar PM, Mürbeth RE, Milligan P, Imbault N, Imoukhuede EB, Theisen M, Jepsen S, Noor RA, Okech B, Kremsner PG, Mordmüller B. A randomized controlled phase Ib trial of the malaria vaccine candidate GMZ2 in African children. PLoS One 2011; 6:e22525. [PMID: 21829466 PMCID: PMC3145647 DOI: 10.1371/journal.pone.0022525] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 06/23/2011] [Indexed: 12/04/2022] Open
Abstract
Background GMZ2 is a fusion protein of Plasmodium falciparum merozoite surface protein 3 (MSP3) and glutamate rich protein (GLURP) that mediates an immune response against the blood stage of the parasite. Two previous phase I clinical trials, one in naïve European adults and one in malaria-exposed Gabonese adults showed that GMZ2 was well tolerated and immunogenic. Here, we present data on safety and immunogenicity of GMZ2 in one to five year old Gabonese children, a target population for future malaria vaccine efficacy trials. Methodology/Principal Findings Thirty children one to five years of age were randomized to receive three doses of either 30 µg or 100 µg of GMZ2, or rabies vaccine. GMZ2, adjuvanted in aluminum hydroxide, was administered on Days 0, 28 and 56. All participants received a full course of their respective vaccination and were followed up for one year. Both 30 µg and 100 µg GMZ2 vaccine doses were well tolerated and induced antibodies and memory B-cells against GMZ2 as well as its antigenic constituents MSP3 and GLURP. After three doses of vaccine, the geometric mean concentration of antibodies to GMZ2 was 19-fold (95%CI: 11,34) higher in the 30 µg GMZ2 group than in the rabies vaccine controls, and 16-fold (7,36) higher in the 100 µg GMZ2 group than the rabies group. Geometric mean concentration of antibodies to MSP3 was 2.7-fold (1.6,4.6) higher in the 30 µg group than in the rabies group and 3.8-fold (1.5,9.6) higher in the 100 µg group. Memory B-cells against GMZ2 developed in both GMZ2 vaccinated groups. Conclusions/Significance Both 30 µg as well as 100 µg intramuscular GMZ2 are immunogenic, well tolerated, and safe in young, malaria-exposed Gabonese children. This result confirms previous findings in naïve and malaria-exposed adults and supports further clinical development of GMZ2. Trial Registration ClinicalTrials.gov NCT00703066
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Affiliation(s)
- Sabine Bélard
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon
| | - Saadou Issifou
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon
| | | | | | | | - Meral Esen
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Rolf Fendel
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | | | | | - Paul Milligan
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Nathalie Imbault
- European Malaria Vaccine Initiative, Statens Serum Institut, Copenhagen, Denmark
| | | | - Michael Theisen
- Department of Clinical Biochemistry and Immunology, Statens Serum Institut and Centre for Medical Parasitology at the Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Brenda Okech
- African Malaria Network Trust, Dar es Salaam, Tanzania
| | - Peter G. Kremsner
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | - Benjamin Mordmüller
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- * E-mail:
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Comparative Immunogenicities of full-length Plasmodium falciparum merozoite surface protein 3 and a 24-kilodalton N-terminal fragment. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2011; 18:1221-8. [PMID: 21632889 DOI: 10.1128/cvi.00064-11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Recombinant Plasmodium falciparum merozoite surface protein 3 (PfMSP3F) and a 24-kDa fragment from its N terminus (MSP3N) that includes the essential conserved domain, which elicits the maximum antibody (Ab)-dependent cellular inhibition (ADCI), were expressed as soluble proteins in Escherichia coli. Both proteins were found to be stable in both soluble and lyophilized forms. Immunization with MSP3F and MSP3N formulated separately with two human-compatible adjuvants, aluminum hydroxide (Alhydrogel) and Montanide ISA 720, produced significant antibody responses in mice and rabbits. Polyclonal Abs against both antigens recognized native MSP3 in the parasite lysate. These two Abs also recognized two synthetic peptides, previously characterized to possess B cell epitopes from the N-terminal region. Antibody depletion assay showed that most of the IgG response is directed toward the N-terminal region of the full protein. Anti-MSP3F and anti-MSP3N rabbit antibodies did not inhibit merozoite invasion or intraerythrocytic development but significantly reduced parasitemia in the presence of human monocytes. The ADCI demonstrated by anti-MSP3N antibodies was comparable to that exhibited by anti-MSP3F antibodies (both generated in rabbit). These results suggest that the N-terminal fragment of MSP3 can be considered a vaccine candidate that can form part of a multigenic vaccine against malaria.
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Zhong D, Bonizzoni M, Zhou G, Wang G, Chen B, Vardo-Zalik A, Cui L, Yan G, Zheng B. Genetic diversity of Plasmodium vivax malaria in China and Myanmar. INFECTION GENETICS AND EVOLUTION 2011; 11:1419-25. [PMID: 21624503 DOI: 10.1016/j.meegid.2011.05.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 05/11/2011] [Accepted: 05/13/2011] [Indexed: 10/18/2022]
Abstract
Genetic diversity and population structure of Plasmodium vivax parasites are valuable to the prediction of the origin and spread of novel variants within and between populations, and to the program evaluation of malaria control measures. Using two polymorphic genetic markers, the merozoite surface protein genes PvMSP-3α and PvMSP-3β, we investigated the genetic diversity of four Southeast Asian P. vivax populations, representing both subtropical and temperate strains with dramatically divergent relapse patterns. PCR amplification of PvMSP-3α and PvMSP-3β genes detected three and four major size polymorphisms among the 235 infections examined, respectively, while restriction analysis detected 15 and 19 alleles, respectively. Samples from different geographical areas differed dramatically in their PvMSP-3α and PvMSP-3β allele composition and frequency. Samples tended to cluster on the basis of their PCR-RFLP polymorphism. These results indicated that different parasite genotypes were circulating in each endemic area, and that geographic isolation may exist. Multiple infections were detected in all four parasite populations, ranging from 20.5% to 31.8%, strongly indicating that P. vivax populations were highly diverse and multiple clonal infections are common in these malaria-hypoendemic regions of Southeast Asia.
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Affiliation(s)
- Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California, Irvine, USA.
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Jordan SJ, Oliveira AL, Neal AT, Hernandez JN, Branch OH, Rayner JC. Antibodies directed against merozoite surface protein-6 are induced by natural exposure to Plasmodium falciparum in a low transmission environment. Parasite Immunol 2011; 33:401-10. [PMID: 21585398 DOI: 10.1111/j.1365-3024.2011.01299.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Malaria caused by Plasmodium falciparum is a major cause of global infant mortality, and there is currently no licensed vaccine that provides protection against infection or disease. Several P. falciparum vaccine targets have undergone early testing, but many more candidates remain with little data to support their development. Plasmodium falciparum Merozoite Surface Protein 6 (PfMSP6) is a candidate of particular interest because it is a member of the PfMSP3 multi-gene family, raising the possibility that vaccine-induced immune responses could cross-react across multiple family members. However, few immunoepidemiological studies of PfMSP6 have been carried out to measure domain-specific anti-PfMSP6 responses. This study investigated anti-PfMSP6 responses in P. falciparum-infected individuals from the Peruvian Amazon, using two different PfMSP6 N-terminal allele antigens and a single C-terminal domain antigen, and compared the responses with both PfMSP6 genotyping data and anti-PfMSP3 response data that had been previously generated for the same samples. Anti-PfMSP6 responses were detected despite the low transmission setting, but were less frequent and of considerably lower intensity than anti-PfMSP3 responses. There was a positive correlation between anti-PfMSP3 and PfMSP6 responses, suggesting that the possibility that PfMSP3 family antigens could induce cross-reactive responses requires further detailed investigation.
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Affiliation(s)
- S J Jordan
- William C Gorgas Center for Geographic Medicine, Division of Infectious Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
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Identification and functional validation of the novel antimalarial resistance locus PF10_0355 in Plasmodium falciparum. PLoS Genet 2011; 7:e1001383. [PMID: 21533027 PMCID: PMC3080868 DOI: 10.1371/journal.pgen.1001383] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 03/25/2011] [Indexed: 11/25/2022] Open
Abstract
The Plasmodium falciparum parasite's ability to adapt to
environmental pressures, such as the human immune system and antimalarial drugs,
makes malaria an enduring burden to public health. Understanding the genetic
basis of these adaptations is critical to intervening successfully against
malaria. To that end, we created a high-density genotyping array that assays
over 17,000 single nucleotide polymorphisms (∼1 SNP/kb), and applied it to
57 culture-adapted parasites from three continents. We characterized genome-wide
genetic diversity within and between populations and identified numerous loci
with signals of natural selection, suggesting their role in recent adaptation.
In addition, we performed a genome-wide association study (GWAS), searching for
loci correlated with resistance to thirteen antimalarials; we detected both
known and novel resistance loci, including a new halofantrine resistance locus,
PF10_0355. Through functional testing we demonstrated that
PF10_0355 overexpression decreases sensitivity to
halofantrine, mefloquine, and lumefantrine, but not to structurally unrelated
antimalarials, and that increased gene copy number mediates resistance. Our GWAS
and follow-on functional validation demonstrate the potential of genome-wide
studies to elucidate functionally important loci in the malaria parasite
genome. Malaria infection with the human pathogen Plasmodium falciparum
results in almost a million deaths each year, mostly in African children.
Efforts to eliminate malaria are underway, but the parasite is adept at eluding
both the human immune response and antimalarial treatments. Thus, it is
important to understand how the parasite becomes resistant to drugs and to
develop strategies to overcome resistance mechanisms. Toward this end, we used
population genetic strategies to identify genetic loci that contribute to
parasite adaptation and to identify candidate genes involved in drug resistance.
We examined over 17,000 genetic variants across the parasite genome in over 50
strains in which we also measured responses to many known antimalarial
compounds. We found a number of genetic loci showing signs of recent natural
selection and a number of loci potentially involved in modulating the
parasite's response to drugs. We further demonstrated that one of the novel
candidate genes (PF10_0355) modulates resistance to the
antimalarial compounds halofantrine, mefloquine, and lumefantrine. Overall, this
study confirms that we can use genome-wide approaches to identify clinically
relevant genes and demonstrates through functional testing that at least one of
these candidate genes is indeed involved in antimalarial drug resistance.
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Malaria immunoepidemiology in low transmission: correlation of infecting genotype and immune response to domains of Plasmodium falciparum merozoite surface protein 3. Infect Immun 2011; 79:2070-8. [PMID: 21383051 DOI: 10.1128/iai.01332-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria caused by Plasmodium falciparum is a major cause of global infant mortality, and no effective vaccine currently exists. Multiple potential vaccine targets have been identified, and immunoepidemiology studies have played a major part in assessing those candidates. When such studies are carried out in high-transmission settings, individuals are often superinfected with complex mixtures of genetically distinct P. falciparum types, making it impossible to directly correlate the genotype of the infecting antigen with the antibody response. In contrast, in regions of low transmission P. falciparum infections are often genetically simple, and direct comparison of infecting genotype and antigen-specific immune responses is possible. As a test of the utility of this approach, responses against several domains and allelic variants of the vaccine candidate P. falciparum merozoite surface protein 3 (PfMSP3) were tested in serum samples collected near Iquitos, Peru. Antibodies recognizing both the conserved C-terminal and the more variable N-terminal domain were identified, but anti-N-terminal responses were more prevalent, of higher titers, and primarily of cytophilic subclasses. Comparing antibody responses to different PfMSP3 variants with the PfMSP3 genotype present at the time of infection showed that anti-N-terminal responses were largely allele class specific, but there was some evidence for responses that cross-reacted across allele classes. Evidence for cross-reactive responses was much stronger when variants within one allele class were tested, which has implications for the rational development of genotype-transcending PfMSP3-based vaccines.
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Ochola LI, Tetteh KKA, Stewart LB, Riitho V, Marsh K, Conway DJ. Allele frequency-based and polymorphism-versus-divergence indices of balancing selection in a new filtered set of polymorphic genes in Plasmodium falciparum. Mol Biol Evol 2010; 27:2344-51. [PMID: 20457586 PMCID: PMC2944029 DOI: 10.1093/molbev/msq119] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Signatures of balancing selection operating on specific gene loci in endemic pathogens can identify candidate targets of naturally acquired immunity. In malaria parasites, several leading vaccine candidates convincingly show such signatures when subjected to several tests of neutrality, but the discovery of new targets affected by selection to a similar extent has been slow. A small minority of all genes are under such selection, as indicated by a recent study of 26 Plasmodium falciparum merozoite-stage genes that were not previously prioritized as vaccine candidates, of which only one (locus PF10_0348) showed a strong signature. Therefore, to focus discovery efforts on genes that are polymorphic, we scanned all available shotgun genome sequence data from laboratory lines of P. falciparum and chose six loci with more than five single nucleotide polymorphisms per kilobase (including PF10_0348) for in-depth frequency-based analyses in a Kenyan population (allele sample sizes >50 for each locus) and comparison of Hudson-Kreitman-Aguade (HKA) ratios of population diversity (π) to interspecific divergence (K) from the chimpanzee parasite Plasmodium reichenowi. Three of these (the msp3/6-like genes PF10_0348 and PF10_0355 and the surf(4.1) gene PFD1160w) showed exceptionally high positive values of Tajima's D and Fu and Li's F indices and have the highest HKA ratios, indicating that they are under balancing selection and should be prioritized for studies of their protein products as candidate targets of immunity. Combined with earlier results, there is now strong evidence that high HKA ratio (as well as the frequency-independent ratio of Watterson's /K) is predictive of high values of Tajima's D. Thus, the former offers value for use in genome-wide screening when numbers of genome sequences within a species are low or in combination with Tajima's D as a 2D test on large population genomic samples.
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Affiliation(s)
- Lynette Isabella Ochola
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast, Kilifi, Kenya
| | - Kevin K. A. Tetteh
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Lindsay B. Stewart
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Victor Riitho
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast, Kilifi, Kenya
| | - Kevin Marsh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research Coast, Kilifi, Kenya
| | - David J. Conway
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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Merozoite surface proteins of the malaria parasite: The MSP1 complex and the MSP7 family. Int J Parasitol 2010; 40:1155-61. [PMID: 20451527 DOI: 10.1016/j.ijpara.2010.04.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 04/22/2010] [Accepted: 04/26/2010] [Indexed: 11/21/2022]
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