1
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Reers AB, Bautista R, McLellan J, Morales B, Garza R, Bol S, Hanson KK, Bunnik EM. Histone modification analysis reveals common regulators of gene expression in liver and blood stage merozoites of Plasmodium parasites. Epigenetics Chromatin 2023; 16:25. [PMID: 37322481 PMCID: PMC10268464 DOI: 10.1186/s13072-023-00500-y] [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: 03/23/2023] [Accepted: 06/06/2023] [Indexed: 06/17/2023] Open
Abstract
Gene expression in malaria parasites is subject to various layers of regulation, including histone post-translational modifications (PTMs). Gene regulatory mechanisms have been extensively studied during the main developmental stages of Plasmodium parasites inside erythrocytes, from the ring stage following invasion to the schizont stage leading up to egress. However, gene regulation in merozoites that mediate the transition from one host cell to the next is an understudied area of parasite biology. Here, we sought to characterize gene expression and the corresponding histone PTM landscape during this stage of the parasite lifecycle through RNA-seq and ChIP-seq on P. falciparum blood stage schizonts, merozoites, and rings, as well as P. berghei liver stage merozoites. In both hepatic and erythrocytic merozoites, we identified a subset of genes with a unique histone PTM profile characterized by a region of H3K4me3 depletion in their promoter. These genes were upregulated in hepatic and erythrocytic merozoites and rings, had roles in protein export, translation, and host cell remodeling, and shared a DNA motif. These results indicate that similar regulatory mechanisms may underlie merozoite formation in the liver and blood stages. We also observed that H3K4me2 was deposited in gene bodies of gene families encoding variant surface antigens in erythrocytic merozoites, which may facilitate switching of gene expression between different members of these families. Finally, H3K18me and H2K27me were uncoupled from gene expression and were enriched around the centromeres in erythrocytic schizonts and merozoites, suggesting potential roles in the maintenance of chromosomal organization during schizogony. Together, our results demonstrate that extensive changes in gene expression and histone landscape occur during the schizont-to-ring transition to facilitate productive erythrocyte infection. The dynamic remodeling of the transcriptional program in hepatic and erythrocytic merozoites makes this stage attractive as a target for novel anti-malarial drugs that may have activity against both the liver and blood stages.
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Affiliation(s)
- Ashley B Reers
- Department of Microbiology, Immunology, and Molecular Genetics, Long School of Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | - Rodriel Bautista
- Department of Microbiology, Immunology, and Molecular Genetics, Long School of Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | - James McLellan
- Department of Molecular Microbiology and Immunology and South Texas Center for Emerging Infectious Diseases, University of Texas San Antonio, San Antonio, TX, USA
| | - Beatriz Morales
- Department of Molecular Microbiology and Immunology and South Texas Center for Emerging Infectious Diseases, University of Texas San Antonio, San Antonio, TX, USA
| | - Rolando Garza
- Department of Microbiology, Immunology, and Molecular Genetics, Long School of Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | - Sebastiaan Bol
- Department of Microbiology, Immunology, and Molecular Genetics, Long School of Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | - Kirsten K Hanson
- Department of Molecular Microbiology and Immunology and South Texas Center for Emerging Infectious Diseases, University of Texas San Antonio, San Antonio, TX, USA
| | - Evelien M Bunnik
- Department of Microbiology, Immunology, and Molecular Genetics, Long School of Medicine, University of Texas Health Science Center, San Antonio, TX, USA.
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2
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Gonzales SJ, Clarke KN, Batugedara G, Garza R, Braddom AE, Reyes RA, Ssewanyana I, Garrison KC, Ippolito GC, Greenhouse B, Bol S, Bunnik EM. A Molecular Analysis of Memory B Cell and Antibody Responses Against Plasmodium falciparum Merozoite Surface Protein 1 in Children and Adults From Uganda. Front Immunol 2022; 13:809264. [PMID: 35720313 PMCID: PMC9201334 DOI: 10.3389/fimmu.2022.809264] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 05/05/2022] [Indexed: 01/18/2023] Open
Abstract
Memory B cells (MBCs) and plasma antibodies against Plasmodium falciparum (Pf) merozoite antigens are important components of the protective immune response against malaria. To gain understanding of how responses against Pf develop in these two arms of the humoral immune system, we evaluated MBC and antibody responses against the most abundant merozoite antigen, full-length Pf merozoite surface protein 1 (PfMSP1FL), in individuals from a region in Uganda with high Pf transmission. Our results showed that PfMSP1FL-specific B cells in adults with immunological protection against malaria were predominantly IgG+ classical MBCs, while children with incomplete protection mainly harbored IgM+ PfMSP1FL-specific classical MBCs. In contrast, anti-PfMSP1FL plasma IgM reactivity was minimal in both children and adults. Instead, both groups showed high plasma IgG reactivity against PfMSP1FL, with broadening of the response against non-3D7 strains in adults. The B cell receptors encoded by PfMSP1FL-specific IgG+ MBCs carried high levels of amino acid substitutions and recognized relatively conserved epitopes on the highly variable PfMSP1 protein. Proteomics analysis of PfMSP119-specific IgG in plasma of an adult revealed a limited repertoire of anti-MSP1 antibodies, most of which were IgG1 or IgG3. Similar to B cell receptors of PfMSP1FL-specific MBCs, anti-PfMSP119 IgGs had high levels of amino acid substitutions and their sequences were predominantly found in classical MBCs, not atypical MBCs. Collectively, these results showed evolution of the PfMSP1-specific humoral immune response with cumulative Pf exposure, with a shift from IgM+ to IgG+ B cell memory, diversification of B cells from germline, and stronger recognition of PfMSP1 variants by the plasma IgG repertoire.
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Affiliation(s)
- S. Jake Gonzales
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Kathleen N. Clarke
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Gayani Batugedara
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Rolando Garza
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Ashley E. Braddom
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Raphael A. Reyes
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Isaac Ssewanyana
- Infectious Disease Research Collaboration, Kampala, Uganda
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Kendra C. Garrison
- Department of Chemical Engineering, University of Texas at Austin, Austin, TX, United States
| | - Gregory C. Ippolito
- Department of Molecular Biosciences and Department of Oncology, Dell Medical School, University of Texas at Austin, Austin, TX, United States
| | - Bryan Greenhouse
- Department of Medicine, University of California San Francisco, San Francisco, CA, United States
| | - Sebastiaan Bol
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Evelien M. Bunnik
- Department of Microbiology, Immunology and Molecular Genetics, Long School of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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3
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Hviid L, Lopez-Perez M. Analysis by Flow Cytometry of α 2-Macroglobulin and Nonimmune IgM-Binding to Plasmodium falciparum-Infected Erythrocytes. Methods Mol Biol 2022; 2470:435-444. [PMID: 35881364 DOI: 10.1007/978-1-0716-2189-9_32] [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] [Indexed: 06/15/2023]
Abstract
Several members of the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family can bind human serum proteins such as IgM and α2-macroglobulin (α2M). This binding seems to play a role in pathogenesis and immune evasion by improving the avidity of PfEMP1-mediated binding to erythrocyte receptors and/or by masking antibody epitopes in PfEMP1. In this protocol, we describe a flow cytometry-based protocol to evaluate IgM- and α2M-binding to intact and unfixed mature-stage IEs. The method can be used for laboratory clones and field isolates.
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Affiliation(s)
- Lars Hviid
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Centre for Medical Parasitology, Rigshospitalet, Copenhagen, Denmark
| | - Mary Lopez-Perez
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark.
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4
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Lopez-Perez M. Single-Cell Sorting of Plasmodium falciparum-Infected Erythrocytes Expressing Particular PfEMP1 Variants. Methods Mol Biol 2022; 2470:79-90. [PMID: 35881340 DOI: 10.1007/978-1-0716-2189-9_8] [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] [Indexed: 06/15/2023]
Abstract
Cultures of Plasmodium falciparum often contain a heterogeneous parasite population. However, several studies require analysis of single infected erythrocytes (IEs) or a clonal parasite population derived from a single parasite. This protocol describes an efficient method for cloning by using fluorescence-activated cell sorting (FACS). For this, an antibody for a particular IEs surface protein it is added to the cell mixture to separate positive and negative IEs for that marker. After the separation, the viable homogeneous population can be used to grow in culture or for molecular analysis.
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Affiliation(s)
- Mary Lopez-Perez
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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5
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Lopez-Perez M, Olsen RW. Immunomagnetic Selection of Plasmodium falciparum-Infected Erythrocytes Expressing Particular PfEMP1 Variants. Methods Mol Biol 2022; 2470:69-78. [PMID: 35881339 DOI: 10.1007/978-1-0716-2189-9_7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Plasmodium falciparum expresses a broad range of proteins on the surface of infected erythrocytes (IEs), including members of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family. This protocol describes an immunomagnetic selection method using PfEMP1-specific antibodies to obtain a parasite clone homogenously expressing a particular PfEMP1 protein. The expression of the corresponding PfEMP1 is later tested by flow cytometry, and the selected parasites can be used for further analysis.
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Affiliation(s)
- Mary Lopez-Perez
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Rebecca Wendelboe Olsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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6
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Sanchez CP, Patra P, Chang SYS, Karathanasis C, Hanebutte L, Kilian N, Cyrklaff M, Heilemann M, Schwarz US, Kudryashev M, Lanzer M. KAHRP dynamically relocalizes to remodeled actin junctions and associates with knob spirals in Plasmodium falciparum-infected erythrocytes. Mol Microbiol 2021; 117:274-292. [PMID: 34514656 DOI: 10.1111/mmi.14811] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 11/28/2022]
Abstract
The knob-associated histidine-rich protein (KAHRP) plays a pivotal role in the pathophysiology of Plasmodium falciparum malaria by forming membrane protrusions in infected erythrocytes, which anchor parasite-encoded adhesins to the membrane skeleton. The resulting sequestration of parasitized erythrocytes in the microvasculature leads to severe disease. Despite KAHRP being an important virulence factor, its physical location within the membrane skeleton is still debated, as is its function in knob formation. Here, we show by super-resolution microscopy that KAHRP initially associates with various skeletal components, including ankyrin bridges, but eventually colocalizes with remnant actin junctions. We further present a 35 Å map of the spiral scaffold underlying knobs and show that a KAHRP-targeting nanoprobe binds close to the spiral scaffold. Single-molecule localization microscopy detected ~60 KAHRP molecules/knob. We propose a dynamic model of KAHRP organization and a function of KAHRP in attaching other factors to the spiral scaffold.
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Affiliation(s)
- Cecilia P Sanchez
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Pintu Patra
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany.,BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Shih-Ying Scott Chang
- Max Planck Institute for Biophysics and Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt, Frankfurt, Germany
| | - Christos Karathanasis
- Institute for Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Lukas Hanebutte
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Nicole Kilian
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Marek Cyrklaff
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Mike Heilemann
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany.,Institute for Physical and Theoretical Chemistry, Goethe-University Frankfurt, Frankfurt, Germany
| | - Ulrich S Schwarz
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany.,BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Mikhail Kudryashev
- Max Planck Institute for Biophysics and Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt, Frankfurt, Germany
| | - Michael Lanzer
- Center of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
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7
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Cao H, Antonopoulos A, Henderson S, Wassall H, Brewin J, Masson A, Shepherd J, Konieczny G, Patel B, Williams ML, Davie A, Forrester MA, Hall L, Minter B, Tampakis D, Moss M, Lennon C, Pickford W, Erwig L, Robertson B, Dell A, Brown GD, Wilson HM, Rees DC, Haslam SM, Alexandra Rowe J, Barker RN, Vickers MA. Red blood cell mannoses as phagocytic ligands mediating both sickle cell anaemia and malaria resistance. Nat Commun 2021; 12:1792. [PMID: 33741926 PMCID: PMC7979802 DOI: 10.1038/s41467-021-21814-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 02/08/2021] [Indexed: 02/06/2023] Open
Abstract
In both sickle cell disease and malaria, red blood cells (RBCs) are phagocytosed in the spleen, but receptor-ligand pairs mediating uptake have not been identified. Here, we report that patches of high mannose N-glycans (Man5-9GlcNAc2), expressed on diseased or oxidized RBC surfaces, bind the mannose receptor (CD206) on phagocytes to mediate clearance. We find that extravascular hemolysis in sickle cell disease correlates with high mannose glycan levels on RBCs. Furthermore, Plasmodium falciparum-infected RBCs expose surface mannose N-glycans, which occur at significantly higher levels on infected RBCs from sickle cell trait subjects compared to those lacking hemoglobin S. The glycans are associated with high molecular weight complexes and protease-resistant, lower molecular weight fragments containing spectrin. Recognition of surface N-linked high mannose glycans as a response to cellular stress is a molecular mechanism common to both the pathogenesis of sickle cell disease and resistance to severe malaria in sickle cell trait.
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Affiliation(s)
- Huan Cao
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | | | - Sadie Henderson
- grid.476695.f0000 0004 0495 4557Scottish National Blood Transfusion Service, Aberdeen, UK
| | - Heather Wassall
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - John Brewin
- grid.46699.340000 0004 0391 9020Department of Haematology, King’s College Hospital, London, UK
| | - Alanna Masson
- grid.417581.e0000 0000 8678 4766Department of Haematology, Aberdeen Royal Infirmary, Aberdeen, UK
| | - Jenna Shepherd
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Gabriela Konieczny
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Bhinal Patel
- grid.7445.20000 0001 2113 8111Department of Life Sciences, Imperial College London, London, UK
| | - Maria-Louise Williams
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Adam Davie
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Megan A. Forrester
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Lindsay Hall
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Beverley Minter
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Dimitris Tampakis
- grid.13097.3c0000 0001 2322 6764Centre for Biological Engineering, School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University and Division of Cancer Studies, King’s College London, London, UK
| | - Michael Moss
- grid.476695.f0000 0004 0495 4557Scottish National Blood Transfusion Service, Aberdeen, UK
| | - Charlotte Lennon
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Wendy Pickford
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Lars Erwig
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Beverley Robertson
- grid.7445.20000 0001 2113 8111Department of Life Sciences, Imperial College London, London, UK
| | - Anne Dell
- grid.46699.340000 0004 0391 9020Department of Haematology, King’s College Hospital, London, UK
| | - Gordon D. Brown
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK ,grid.8391.30000 0004 1936 8024Medical Medical Research Council Centre for Medical Mycology at the University of Exeter, Exeter, UK
| | - Heather M. Wilson
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - David C. Rees
- grid.46699.340000 0004 0391 9020Department of Haematology, King’s College Hospital, London, UK
| | - Stuart M. Haslam
- grid.7445.20000 0001 2113 8111Department of Life Sciences, Imperial College London, London, UK
| | - J. Alexandra Rowe
- grid.4305.20000 0004 1936 7988Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Robert N. Barker
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK
| | - Mark A. Vickers
- grid.7107.10000 0004 1936 7291School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen, UK ,grid.476695.f0000 0004 0495 4557Scottish National Blood Transfusion Service, Aberdeen, UK ,grid.417581.e0000 0000 8678 4766Department of Haematology, Aberdeen Royal Infirmary, Aberdeen, UK
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8
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Doritchamou JYA, Suurbaar J, Tuikue Ndam N. Progress and new horizons toward a VAR2CSA-based placental malaria vaccine. Expert Rev Vaccines 2021; 20:215-226. [PMID: 33472449 DOI: 10.1080/14760584.2021.1878029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Introduction: Several malaria vaccines are under various phases of development with some promising results. In placental malaria (PM) a deliberately anti-disease approach is considered as many studies have underlined the key role of VAR2CSA protein, which therefore represents the leading vaccine candidate. However, evidence indicates that VAR2CSA antigenic polymorphism remains an obstacle to overcome.Areas covered: This review analyzes the progress made thus far in developing a VAR2CSA-based vaccine, and addresses the current issues and challenges that must be overcome to develop an effective PM vaccine.Expert opinion: Phase I trials of PAMVAC and PRIMVAC VAR2CSA vaccines have shown more or less satisfactory results with regards to safety and immunogenicity. The second generation of VAR2CSA-based vaccines could benefit from optimization approaches to broaden the activity spectrum against various placenta-binding isolates through continued advances in the structural understanding of the interaction with CSA.
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Affiliation(s)
- Justin Yai Alamou Doritchamou
- Laboratory of Malaria Immunology & Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jennifer Suurbaar
- Université de Paris, MERIT, IRD, F-75006 Paris, France.,Noguchi Memorial Institute for Medical Research, Department of Immunology, University of Ghana, Accra, Ghana
| | - Nicaise Tuikue Ndam
- Université de Paris, MERIT, IRD, F-75006 Paris, France.,Noguchi Memorial Institute for Medical Research, Department of Immunology, University of Ghana, Accra, Ghana
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9
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van der Puije W, Wang CW, Sudharson S, Hempel C, Olsen RW, Dalgaard N, Ofori MF, Hviid L, Kurtzhals JAL, Staalsoe T. In vitro selection for adhesion of Plasmodium falciparum-infected erythrocytes to ABO antigens does not affect PfEMP1 and RIFIN expression. Sci Rep 2020; 10:12871. [PMID: 32732983 PMCID: PMC7393120 DOI: 10.1038/s41598-020-69666-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 07/09/2020] [Indexed: 11/09/2022] Open
Abstract
Plasmodium falciparum causes the most severe form of malaria in humans. The adhesion of the infected erythrocytes (IEs) to endothelial receptors (sequestration) and to uninfected erythrocytes (rosetting) are considered major elements in the pathogenesis of the disease. Both sequestration and rosetting appear to involve particular members of several IE variant surface antigens (VSAs) as ligands, interacting with multiple vascular host receptors, including the ABO blood group antigens. In this study, we subjected genetically distinct P. falciparum parasites to in vitro selection for increased IE adhesion to ABO antigens in the absence of potentially confounding receptors. The selection resulted in IEs that adhered stronger to pure ABO antigens, to erythrocytes, and to various human cell lines than their unselected counterparts. However, selection did not result in marked qualitative changes in transcript levels of the genes encoding the best-described VSA families, PfEMP1 and RIFIN. Rather, overall transcription of both gene families tended to decline following selection. Furthermore, selection-induced increases in the adhesion to ABO occurred in the absence of marked changes in immune IgG recognition of IE surface antigens, generally assumed to target mainly VSAs. Our study sheds new light on our understanding of the processes and molecules involved in IE sequestration and rosetting.
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Affiliation(s)
- William van der Puije
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana.,Centre for Medical Parasitology, Department of Clinical Microbiology, Rigshospitalet, Ole Maaløes Vej, 7602, 2200, Copenhagen, Denmark
| | - Christian W Wang
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Srinidhi Sudharson
- Centre for Medical Parasitology, Department of Clinical Microbiology, Rigshospitalet, Ole Maaløes Vej, 7602, 2200, Copenhagen, Denmark
| | - Casper Hempel
- Centre for Medical Parasitology, Department of Clinical Microbiology, Rigshospitalet, Ole Maaløes Vej, 7602, 2200, Copenhagen, Denmark
| | - Rebecca W Olsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nanna Dalgaard
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael F Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lars Hviid
- Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark.,Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen A L Kurtzhals
- Centre for Medical Parasitology, Department of Clinical Microbiology, Rigshospitalet, Ole Maaløes Vej, 7602, 2200, Copenhagen, Denmark.,Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Trine Staalsoe
- Centre for Medical Parasitology, Department of Clinical Microbiology, Rigshospitalet, Ole Maaløes Vej, 7602, 2200, Copenhagen, Denmark. .,Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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10
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Chêne A, Gangnard S, Guadall A, Ginisty H, Leroy O, Havelange N, Viebig NK, Gamain B. Preclinical immunogenicity and safety of the cGMP-grade placental malaria vaccine PRIMVAC. EBioMedicine 2019; 42:145-156. [PMID: 30885725 PMCID: PMC6491931 DOI: 10.1016/j.ebiom.2019.03.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/26/2019] [Accepted: 03/04/2019] [Indexed: 11/28/2022] Open
Abstract
Background VAR2CSA is the lead antigen for developing a vaccine that would protect pregnant women against placental malaria. A multi-system feasibility study has identified E. coli as a suitable bacterial expression platform allowing the production of recombinant VAR2CSA-DBL1x-2x (PRIMVAC) to envisage a prompt transition to current Good Manufacturing Practice (cGMP) vaccine production. Methods Extensive process developments were undertaken to produce cGMP grade PRIMVAC to permit early phase clinical trials. PRIMVAC stability upon storage was assessed over up to 3 years. A broad toxicology investigation was carried out in rats allowing meanwhile the analysis of PRIMVAC immunogenicity. Findings We describe the successful cGMP production of 4. 65 g of PRIMVAC. PRIMVAC drug product was stable and potent for up to 3 years upon storage at −20 °C and showed an absence of toxicity in rats. PRIMVAC adjuvanted with Alhydrogel® or GLA-SE was able to generate antibodies able to recognize VAR2CSA expressed at the surface of erythrocytes infected with different strains. These antibodies also inhibit the interaction of the homologous NF54-CSA strain and to a lower extend of heterologous strains to CSA. Interpretation This work paved the way for the clinical development of an easily scalable low cost effective vaccine that could protect against placental malaria and prevent an estimated 10,000 maternal and 200,000 infant deaths annually. Fund This work was supported by a grant from the Bundesministerium für Bildung und Forschung (BMBF), Germany through Kreditanstalt für Wiederaufbau (KfW) (Reference No: 202060457) and through funding from Irish Aid, Department of Foreign Affairs and Trade, Ireland.
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Affiliation(s)
- Arnaud Chêne
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Severe Malaria Pathogenesis group, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Stéphane Gangnard
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Severe Malaria Pathogenesis group, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Anna Guadall
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Severe Malaria Pathogenesis group, Laboratoire d'Excellence GR-Ex, Paris, France
| | - Hervé Ginisty
- GTP Technology, l'Occitane, 31670 Labège, Cedex, France
| | - Odile Leroy
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Voßstraße 2, 69115 Heidelberg, Germany
| | - Nicolas Havelange
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Voßstraße 2, 69115 Heidelberg, Germany
| | - Nicola K Viebig
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Voßstraße 2, 69115 Heidelberg, Germany
| | - Benoît Gamain
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge UMR_S1134, Severe Malaria Pathogenesis group, Laboratoire d'Excellence GR-Ex, Paris, France.
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11
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Larsen MD, Quintana MDP, Ditlev SB, Bayarri-Olmos R, Ofori MF, Hviid L, Garred P. Evasion of Classical Complement Pathway Activation on Plasmodium falciparum-Infected Erythrocytes Opsonized by PfEMP1-Specific IgG. Front Immunol 2019; 9:3088. [PMID: 30666256 PMCID: PMC6330326 DOI: 10.3389/fimmu.2018.03088] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 12/13/2018] [Indexed: 01/01/2023] Open
Abstract
Members of the PfEMP1 protein family are expressed on the surface of P. falciparum-infected erythrocytes (IEs), where they contribute to the pathogenesis of malaria and are important targets of acquired immunity. Although the PfEMP1-specific antibody response is dominated by the opsonizing and complement-fixing subclasses IgG1 and IgG3, activation of the classical complement pathway by antibody-opsonized IEs does not appear to be a major immune effector mechanism. To study the molecular background for this, we used ELISA and flow cytometry to assess activation of the classical component pathway by recombinant and native PfEMP1 antigen opsonized by polyclonal and monoclonal PfEMP1-specific human IgG. Polyclonal IgG specific for VAR2CSA-type PfEMP1 purified from a pool of human immune plasma efficiently activated the classical complement pathway when bound to recombinant PfEMP1 in ELISA. In contrast, no activation of complement could be detected by flow cytometry when the same IgG preparation was used to opsonize IEs expressing the corresponding native PfEMP1 antigen. After engineering of a VAR2CSA-specific monoclonal antibody to facilitate its on-target hexamerization, complement activation was detectable in an ELISA optimized for uniform orientation of the immobilized antigen. In contrast, the antibody remained unable to activate complement when bound to native VAR2CSA on IEs. Our data suggest that the display of PfEMP1 proteins on IEs is optimized to prevent activation of the classical complement pathway, and thus represents a hitherto unappreciated parasite strategy to evade acquired immunity to malaria.
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Affiliation(s)
- Mads Delbo Larsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Copenhagen, Denmark
| | - Maria Del Pilar Quintana
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sisse Bolm Ditlev
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rafael Bayarri-Olmos
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Copenhagen, Denmark
| | - Michael Fokuo Ofori
- Department of Immunology, Noguchi Memorial Institute of Medical Research, University of Ghana, Accra, Ghana
| | - Lars Hviid
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Centre for Medical Parasitology, Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Peter Garred
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Rigshospitalet, Copenhagen, Denmark
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12
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Olsen RW, Ecklu-Mensah G, Bengtsson A, Ofori MF, Lusingu JPA, Castberg FC, Hviid L, Adams Y, Jensen ATR. Natural and Vaccine-Induced Acquisition of Cross-Reactive IgG-Inhibiting ICAM-1-Specific Binding of a Plasmodium falciparum PfEMP1 Subtype Associated Specifically with Cerebral Malaria. Infect Immun 2018; 86:e00622-17. [PMID: 29426042 PMCID: PMC5865037 DOI: 10.1128/iai.00622-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 01/25/2018] [Indexed: 12/17/2022] Open
Abstract
Cerebral malaria (CM) is a potentially deadly outcome of Plasmodium falciparum malaria that is precipitated by sequestration of infected erythrocytes (IEs) in the brain. The adhesion of IEs to brain endothelial cells is mediated by a subtype of parasite-encoded erythrocyte membrane protein 1 (PfEMP1) that facilitates dual binding to host intercellular adhesion molecule 1 (ICAM-1) and endothelial protein receptor C (EPCR). The PfEMP1 subtype is characterized by the presence of a particular motif (DBLβ_motif) in the constituent ICAM-1-binding DBLβ domain. The rate of natural acquisition of DBLβ_motif-specific IgG antibodies and the ability to induce such antibodies by vaccination are unknown, and the aim of this study was to provide such data. We used an enzyme-linked immunosorbent assay (ELISA) to measure DBLβ-specific IgG in plasma from Ghanaian children with malaria. The ability of human immune plasma and DBLβ-specific rat antisera to inhibit the interaction between ICAM-1 and DBLβ was assessed using ELISA and in vitro assays of IE adhesion under flow. The acquisition of DBLβ_motif-specific IgG coincided with age-specific susceptibility to CM. Broadly cross-reactive antibodies inhibiting the interaction between ICAM-1 and DBLβ_motif domains were detectable in immune plasma and in sera of rats immunized with specific DBLβ_motif antigens. Importantly, antibodies against the DBLβ_motif inhibited ICAM-1-specific in vitro adhesion of erythrocytes infected by four of five P. falciparum isolates from cerebral malaria patients. We conclude that natural exposure to P. falciparum as well as immunization with specific DBLβ_motif antigens can induce cross-reactive antibodies that inhibit the interaction between ICAM-1 and a broad range of DBLβ_motif domains. These findings raise hope that a vaccine designed specifically to prevent CM is feasible.
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MESH Headings
- Adolescent
- Amino Acid Motifs
- Antibodies, Neutralizing/immunology
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/immunology
- Binding Sites
- Child
- Child, Preschool
- Cross Reactions/immunology
- Ghana
- Humans
- Immunoglobulin G/immunology
- Immunoglobulin G/metabolism
- Infant
- Intercellular Adhesion Molecule-1/metabolism
- Malaria Vaccines/immunology
- Malaria, Cerebral/immunology
- Malaria, Cerebral/metabolism
- Malaria, Cerebral/parasitology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/metabolism
- Malaria, Falciparum/parasitology
- Plasmodium falciparum/immunology
- Protein Binding/immunology
- Protein Interaction Domains and Motifs
- Protozoan Proteins/chemistry
- Protozoan Proteins/immunology
- Protozoan Proteins/metabolism
- Tanzania
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Affiliation(s)
- Rebecca W Olsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gertrude Ecklu-Mensah
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Anja Bengtsson
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael F Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - John P A Lusingu
- National Institute for Medical Research, Tanga Centre, Tanga City, Tanzania
| | - Filip C Castberg
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Clinical Microbiology, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Yvonne Adams
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Anja T R Jensen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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13
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A versatile, high through-put, bead-based phagocytosis assay for Plasmodium falciparum. Sci Rep 2017; 7:14705. [PMID: 29089635 PMCID: PMC5665980 DOI: 10.1038/s41598-017-13900-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/02/2017] [Indexed: 11/08/2022] Open
Abstract
Antibody-mediated phagocytosis is an important immune effector mechanism against Plasmodium falciparum-infected erythrocytes (IE); however, current phagocytosis assays use IE collected from infected individuals or from in vitro cultures of P. falciparum, making them prone to high variation. A simple, high-throughput flow cytometric assay was developed that uses THP-1 cells and fluorescent beads covalently-coupled with the malarial antigen VAR2CSA. The assay is highly repeatable, provides both the overall percent phagocytosis and semi-quantitates the number of antigen-coupled beads internalized.
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14
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Dobbs KR, Embury P, Vulule J, Odada PS, Rosa BA, Mitreva M, Kazura JW, Dent AE. Monocyte dysregulation and systemic inflammation during pediatric falciparum malaria. JCI Insight 2017; 2:95352. [PMID: 28931756 DOI: 10.1172/jci.insight.95352] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/16/2017] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Inflammation and monocytes are thought to be important to human malaria pathogenesis. However, the relationship of inflammation and various monocyte functions to acute malaria, recovery from acute malaria, and asymptomatic parasitemia in endemic populations is poorly understood. METHODS We evaluated plasma cytokine levels, monocyte subsets, monocyte functional responses, and monocyte inflammatory transcriptional profiles of 1- to 10-year-old Kenyan children at the time of presentation with acute uncomplicated malaria and at recovery 6 weeks later; these results were compared with analogous data from asymptomatic children and adults in the same community. RESULTS Acute malaria was marked by elevated levels of proinflammatory and regulatory cytokines and expansion of the inflammatory "intermediate" monocyte subset that returned to levels of healthy asymptomatic children 6 weeks later. Monocytes displayed activated phenotypes during acute malaria, with changes in surface expression of markers important to innate and adaptive immunity. Functionally, acute malaria monocytes and monocytes from asymptomatic infected children had impaired phagocytosis of P. falciparum-infected erythrocytes relative to asymptomatic children with no blood-stage infection. Monocytes from both acute malaria and recovery time points displayed strong and equivalent cytokine responsiveness to innate immune agonists that were independent of infection status. Monocyte transcriptional profiles revealed regulated and balanced proinflammatory and antiinflammatory and altered phagocytosis gene expression patterns distinct from malaria-naive monocytes. CONCLUSION These observations provide insights into monocyte functions and the innate immune response during uncomplicated malaria and suggest that asymptomatic parasitemia in children is not clinically benign. FUNDING Support for this work was provided by NIH/National Institute of Allergy and Infectious Diseases (R01AI095192-05), the Burroughs Wellcome Fund/American Society of Tropical Medicine and Hygiene, and the Rainbow Babies & Children's Foundation.
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Affiliation(s)
- Katherine R Dobbs
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA.,Division of Pediatric Infectious Diseases, University Hospitals Rainbow Babies and Children's Hospital, Cleveland, Ohio, USA
| | - Paula Embury
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA
| | - John Vulule
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Peter S Odada
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Bruce A Rosa
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Makedonka Mitreva
- McDonnell Genome Institute, Washington University School of Medicine, St. Louis, Missouri, USA
| | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA
| | - Arlene E Dent
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA.,Division of Pediatric Infectious Diseases, University Hospitals Rainbow Babies and Children's Hospital, Cleveland, Ohio, USA
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15
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Dinko B, King E, Targett GAT, Sutherland CJ. Antibody responses to surface antigens of Plasmodium falciparum gametocyte-infected erythrocytes and their relation to gametocytaemia. Parasite Immunol 2017; 38:352-64. [PMID: 27084060 PMCID: PMC5089589 DOI: 10.1111/pim.12323] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 04/06/2016] [Indexed: 01/13/2023]
Abstract
An essential element for continuing transmission of Plasmodium falciparum is the availability of mature gametocytes in human peripheral circulation for uptake by mosquitoes. Natural immune responses to circulating gametocytes may play a role in reducing transmission from humans to mosquitoes. Here, antibody recognition of the surface of mature intra‐erythrocytic gametocytes produced either by a laboratory‐adapted parasite, 3D7, or by a recent clinical isolate of Kenyan origin (HL1204), was evaluated longitudinally in a cohort of Ghanaian school children by flow cytometry. This showed that a proportion of children exhibited antibody responses that recognized gametocyte surface antigens on one or both parasite lines. A subset of the children maintained detectable anti‐gametocyte surface antigen (GSA) antibody levels during the 5 week study period. There was indicative evidence that children with anti‐GSA antibodies present at enrolment were less likely to have patent gametocytaemia at subsequent visits (odds ratio = 0·29, 95% CI 0·06–1·05; P = 0·034). Our data support the existence of antigens on the surface of gametocyte‐infected erythrocytes, but further studies are needed to confirm whether antibodies against them reduce gametocyte carriage. The identification of GSA would allow their evaluation as potential anti‐gametocyte vaccine candidates and/or biomarkers for gametocyte carriage.
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Affiliation(s)
- B Dinko
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - E King
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - G A T Targett
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - C J Sutherland
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
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16
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Hapuarachchi SV, Cobbold SA, Shafik SH, Dennis ASM, McConville MJ, Martin RE, Kirk K, Lehane AM. The Malaria Parasite's Lactate Transporter PfFNT Is the Target of Antiplasmodial Compounds Identified in Whole Cell Phenotypic Screens. PLoS Pathog 2017; 13:e1006180. [PMID: 28178359 PMCID: PMC5298231 DOI: 10.1371/journal.ppat.1006180] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 01/11/2017] [Indexed: 11/19/2022] Open
Abstract
In this study the ‘Malaria Box’ chemical library comprising 400 compounds with antiplasmodial activity was screened for compounds that perturb the internal pH of the malaria parasite, Plasmodium falciparum. Fifteen compounds induced an acidification of the parasite cytosol. Two of these did so by inhibiting the parasite’s formate nitrite transporter (PfFNT), which mediates the H+-coupled efflux from the parasite of lactate generated by glycolysis. Both compounds were shown to inhibit lactate transport across the parasite plasma membrane, and the transport of lactate by PfFNT expressed in Xenopus laevis oocytes. PfFNT inhibition caused accumulation of lactate in parasitised erythrocytes, and swelling of both the parasite and parasitised erythrocyte. Long-term exposure of parasites to one of the inhibitors gave rise to resistant parasites with a mutant form of PfFNT that showed reduced inhibitor sensitivity. This study provides the first evidence that PfFNT is a druggable antimalarial target. The emergence and spread of Plasmodium falciparum strains resistant to leading antimalarial drugs has intensified the need to discover and develop drugs that kill the parasite via new mechanisms. Here we screened compounds that are known to inhibit P. falciparum growth for their effects on the pH inside the parasite. We identified fifteen compounds that decrease the pH inside the parasite, and determined the mechanism by which two of these, MMV007839 and MMV000972, disrupt pH and kill the parasite. The two compounds were found to inhibit the P. falciparum formate nitrite transporter (PfFNT), a transport protein that is located on the parasite surface and that serves to remove the waste product lactic acid from the parasite. The compounds inhibited both the H+-coupled transport of lactate across the parasite plasma membrane and the transport of lactate by PfFNT expressed in Xenopus oocytes. In addition to disrupting pH, PfFNT inhibition led to a build-up of lactate in the parasite-infected red blood cell and the swelling of both the parasite and the infected red blood cell. Exposing parasites to MMV007839 over a prolonged time period gave rise to resistant parasites with a mutant form of PfFNT that was less sensitive to the compound. This study validates PfFNT as a novel antimalarial drug target.
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Affiliation(s)
| | - Simon A Cobbold
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Sarah H Shafik
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Adelaide S M Dennis
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Malcolm J McConville
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, VIC, Australia
| | - Rowena E Martin
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Kiaran Kirk
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Adele M Lehane
- Research School of Biology, Australian National University, Canberra, ACT, Australia
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17
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Pehrson C, Heno KK, Adams Y, Resende M, Mathiesen L, Soegaard M, de Jongh WA, Theander TG, Salanti A, Nielsen MA. Comparison of functional assays used in the clinical development of a placental malaria vaccine. Vaccine 2016; 35:610-618. [PMID: 28012775 DOI: 10.1016/j.vaccine.2016.12.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/05/2016] [Accepted: 12/08/2016] [Indexed: 01/06/2023]
Abstract
BACKGROUND Malaria in pregnancy is associated with significant morbidity in pregnant women and their offspring. Plasmodium falciparum infected erythrocytes (IE) express VAR2CSA that mediates binding to chondroitin sulphate A (CSA) in the placenta. Two VAR2CSA-based vaccines for placental malaria are in clinical development. The purpose of this study was to evaluate the robustness and comparability of binding inhibition assays used in the clinical development of placental malaria vaccines. METHODS The ability of sera from animals immunised with different VAR2CSA constructs to inhibit IE binding to CSA was investigated in three in vitro assays using 96-well plates, petri dishes, capillary flow and an ex vivo placental perfusion assay. RESULTS The inter-assay variation was not uniform between assays and ranged from above ten-fold in the flow assay to two-fold in the perfusion assay. The intra-assay variation was highest in the petri dish assay. A positive correlation between IE binding avidity and the level of binding after antibody inhibition in the petri dish assay indicate that high avidity IE binding is more difficult to inhibit. The highest binding inhibition sensitivity was found in the 96-well and petri dish assays compared to the flow and perfusion assays where binding inhibition required higher antibody titers. CONCLUSIONS The inhibitory capacity of antibodies is not easily translated between assays and the high sensitivity of the 96-well and petri dish assays stresses the need for comparing serial dilutions of serum. Furthermore, IE binding avidity must be in the same range when comparing data from different days. There was an overall concordance in the capacity of antibody-mediated inhibition, when comparing the in vitro assays with the perfusion assay, which more closely represents in vivo conditions. Importantly the ID1-ID2a protein in a liposomal formulation, currently in a phase I trial, effectively induced antibodies that inhibited IE adhesion in placental tissue.
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Affiliation(s)
- Caroline Pehrson
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Kristine K Heno
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Yvonne Adams
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Line Mathiesen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353 Copenhagen, Denmark.
| | - Max Soegaard
- ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
| | - Willem A de Jongh
- ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
| | - Thor G Theander
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Ali Salanti
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Morten A Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
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18
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Bruske EI, Dimonte S, Enderes C, Tschan S, Flötenmeyer M, Koch I, Berger J, Kremsner P, Frank M. In Vitro Variant Surface Antigen Expression in Plasmodium falciparum Parasites from a Semi-Immune Individual Is Not Correlated with Var Gene Transcription. PLoS One 2016; 11:e0166135. [PMID: 27907004 PMCID: PMC5132323 DOI: 10.1371/journal.pone.0166135] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 10/24/2016] [Indexed: 12/17/2022] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is considered to be the main variant surface antigen (VSA) of Plasmodium falciparum and is mainly localized on electron-dense knobs in the membrane of the infected erythrocyte. Switches in PfEMP1 expression provide the basis for antigenic variation and are thought to be critical for parasite persistence during chronic infections. Recently, strain transcending anti-PfEMP1 immunity has been shown to develop early in life, challenging the role of PfEMP1 in antigenic variation during chronic infections. In this work we investigate how P. falciparum achieves persistence during a chronic asymptomatic infection. The infected individual (MOA) was parasitemic for 42 days and multilocus var gene genotyping showed persistence of the same parasite population throughout the infection. Parasites from the beginning of the infection were adapted to tissue culture and cloned by limiting dilution. Flow cytometry using convalescent serum detected a variable surface recognition signal on isogenic clonal parasites. Quantitative real-time PCR with a field isolate specific var gene primer set showed that the surface recognition signal was not correlated with transcription of individual var genes. Strain transcending anti-PfEMP1 immunity of the convalescent serum was demonstrated with CD36 selected and PfEMP1 knock-down NF54 clones. In contrast, knock-down of PfEMP1 did not have an effect on the antibody recognition signal in MOA clones. Trypsinisation of the membrane surface proteins abolished the surface recognition signal and immune electron microscopy revealed that antibodies from the convalescent serum bound to membrane areas without knobs and with knobs. Together the data indicate that PfEMP1 is not the main variable surface antigen during a chronic infection and suggest a role for trypsin sensitive non-PfEMP1 VSAs for parasite persistence in chronic infections.
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Affiliation(s)
- Ellen Inga Bruske
- Institute of Tropical Medicine, University of Tuebingen, Tuebingen, Germany
| | - Sandra Dimonte
- Institute of Tropical Medicine, University of Tuebingen, Tuebingen, Germany
| | - Corinna Enderes
- Institute of Tropical Medicine, University of Tuebingen, Tuebingen, Germany
| | - Serena Tschan
- Institute of Tropical Medicine, University of Tuebingen, Tuebingen, Germany
| | | | - Iris Koch
- Max Planck Institute for Developmental Biology, Tuebingen, Germany
| | - Jürgen Berger
- Max Planck Institute for Developmental Biology, Tuebingen, Germany
| | - Peter Kremsner
- Institute of Tropical Medicine, University of Tuebingen, Tuebingen, Germany
- CERMEL (Centre de Recherche Médicale de Lambaréné), Lambaréné, Gabon
| | - Matthias Frank
- Institute of Tropical Medicine, University of Tuebingen, Tuebingen, Germany
- CERMEL (Centre de Recherche Médicale de Lambaréné), Lambaréné, Gabon
- * E-mail:
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19
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Carlos BC, Fotoran WL, Menezes MJ, Cabral FJ, Bastos MF, Costa FT, Sousa-Neto JA, Ribolla PE, Wunderlich G, Ferreira MU. Expressed var gene repertoire and variant surface antigen diversity in a shrinking Plasmodium falciparum population. Exp Parasitol 2016; 170:90-99. [DOI: 10.1016/j.exppara.2016.09.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 09/01/2016] [Accepted: 09/20/2016] [Indexed: 10/21/2022]
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20
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Relationship between Antibody Levels, IgG Binding to Plasmodium falciparum-Infected Erythrocytes, and Disease Outcome in Hospitalized Urban Malaria Patients from Dakar, Sénégal. BIOMED RESEARCH INTERNATIONAL 2016; 2016:5381956. [PMID: 27563669 PMCID: PMC4987455 DOI: 10.1155/2016/5381956] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/06/2016] [Accepted: 05/24/2016] [Indexed: 11/17/2022]
Abstract
Background. Management of clinical malaria requires the development of reliable diagnostic methods and efficient biomarkers for follow-up of patients. Protection is partly based on IgG responses to parasite antigens exposed at the surface of infected erythrocytes (iRBCs). These IgG responses appeared low during clinical infection, particularly in severe disease. Methods. We analyzed the IgG binding capacity to the surface of live erythrocytes infected by knob positive FCR3 strain. Sera from 69 cerebral malaria (CM) and 72 mild malaria (MM) cases were analyzed by ELISA for IgG responses to five antigens from iRBC and by flow cytometry for IgG binding as expressed in labeling index ratio (LIR). The relationship between IgG levels, LIR, parasitemia, age, and the clinical outcomes was evaluated. Results. We found a significant decrease of LIR in adult CM fatal cases compared to surviving patients (p = 0.019). In MM, LIRs were correlated to IgG anti-iRBC and anti-PfEMP3/5 levels. In CM, no correlation was found between LIR, IgG levels, and parasitemia. Conclusion. The IgG binding assay was able to discriminate outcome of cerebral malaria cases and it deserves further development as a potential functional-associated assay for symptomatic malaria analysis.
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Dekel E, Rivkin A, Heidenreich M, Nadav Y, Ofir-Birin Y, Porat Z, Regev-Rudzki N. Identification and classification of the malaria parasite blood developmental stages, using imaging flow cytometry. Methods 2016; 112:157-166. [PMID: 27350362 DOI: 10.1016/j.ymeth.2016.06.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 06/02/2016] [Accepted: 06/22/2016] [Indexed: 10/21/2022] Open
Abstract
Malaria is the most devastating parasitic disease of humans, caused by the unicellular protozoa of the Plasmodium genus, such as Plasmodium falciparum (Pf) and is responsible for up to a million deaths each year. Pf life cycle is complex, with transmission of the parasite between humans via mosquitos involving a remarkable series of morphological transformations. In the bloodstream, the parasites undergo asexual multiplications inside the red blood cell (RBC), where they mature through the ring (R), trophozoite (T) and schizont (S) stages, and sexual development, resulting in gametocytes (G). All symptoms of malaria pathology are caused by the asexual blood stage parasites. Flow cytometry methods were previously used to detect malaria infected (i) RBCs, in live or fixed cells, using DNA (Hoechst) and RNA (Thiazole Orange) stains. Here, by using imaging flow cytometry, we developed improved methods of identifying and quantifying each of the four parasite blood stages (R, T, S and G). This technique allows multi-channel, high resolution imaging of individual parasites, as well as detailed morphological quantification of Pf-iRBCs cultures. Moreover, by measuring iRBC morphological properties, we can eliminate corrupted and extracellular (dying) parasites from the analysis, providing accurate quantification and robust measurement of the parasitemia profile. This new method is a valuable tool in malaria molecular biology research and drug screen assays.
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Affiliation(s)
- Elya Dekel
- Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Anna Rivkin
- Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Meta Heidenreich
- Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Yotam Nadav
- Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Yifat Ofir-Birin
- Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ziv Porat
- Flow Cytometry Unit, Biological Services Department, Weizmann Institute of Science, Rehovot, Israel.
| | - Neta Regev-Rudzki
- Faculty of Biochemistry, Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
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22
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Pehrson C, Mathiesen L, Heno KK, Salanti A, Resende M, Dzikowski R, Damm P, Hansson SR, King CL, Schneider H, Wang CW, Lavstsen T, Theander TG, Knudsen LE, Nielsen MA. Adhesion of Plasmodium falciparum infected erythrocytes in ex vivo perfused placental tissue: a novel model of placental malaria. Malar J 2016; 15:292. [PMID: 27230523 PMCID: PMC4881162 DOI: 10.1186/s12936-016-1342-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 05/12/2016] [Indexed: 11/10/2022] Open
Abstract
Background Placental malaria occurs when Plasmodium falciparum infected erythrocytes sequester in the placenta. Placental parasite isolates bind to chondroitin sulphate A (CSA) by expression of VAR2CSA on the surface of infected erythrocytes, but may sequester by other VAR2CSA mediated mechanisms, such as binding to immunoglobulins. Furthermore, other parasite antigens have been associated with placental malaria. These findings have important implications for placental malaria vaccine design. The objective of this study was to adapt and describe a biologically relevant model of parasite adhesion in intact placental tissue. Results The ex vivo placental perfusion model was modified to study adhesion of infected erythrocytes binding to CSA, endothelial protein C receptor (EPCR) or a transgenic parasite where P. falciparum erythrocyte membrane protein 1 expression had been shut down. Infected erythrocytes expressing VAR2CSA accumulated in perfused placental tissue whereas the EPCR binding and the transgenic parasite did not. Soluble CSA and antibodies specific against VAR2CSA inhibited binding of infected erythrocytes. Conclusion The ex vivo model provides a novel way of studying receptor-ligand interactions and antibody mediated inhibition of binding in placental malaria. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1342-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Caroline Pehrson
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
| | - Line Mathiesen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353, Copenhagen, Denmark
| | - Kristine K Heno
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ron Dzikowski
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel
| | - Peter Damm
- Department of Obstetrics, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark
| | - Stefan R Hansson
- Division of Obstetrics and Gynecology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Christopher L King
- Center for Global Health and Diseases, Case Western Reserve University and Veterans Affairs Medical Center, Cleveland, USA
| | - Henning Schneider
- Department of Obstetrics and Gynecology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Christian W Wang
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thor G Theander
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lisbeth E Knudsen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353, Copenhagen, Denmark
| | - Morten A Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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23
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Arnot DE, Jensen ATR. Antigenic Variation and the Genetics and Epigenetics of the PfEMP1 Erythrocyte Surface Antigens in Plasmodium falciparum Malaria. ADVANCES IN APPLIED MICROBIOLOGY 2016; 74:77-96. [PMID: 21459194 DOI: 10.1016/b978-0-12-387022-3.00007-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
How immunity to malaria develops remains one of the great unresolved issues in bio-medicine and resolution of its various paradoxes is likely to be the key to developing effective malaria vaccines. The basic epidemiological observations are; under conditions of intense natural transmission, humans do become immune to P. falciparum malaria, but this is a slow process requiring multiple disease episodes which many, particularly young children, do not survive. Adult survivors are immune to the symptoms of malaria, and unless pregnant, can control the growth of most or all new inoculations. Sterile immunity is not achieved and chronic parasitization of apparently healthy adults is the norm. In this article, we analyse the best understood malaria "antigenic variation" system, that based on Plasmodium falciparum's PfEMP1-type cytoadhesion antigens, and critically review recent literature on the function and control of this multi-gene family of parasite variable surface antigens.
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Affiliation(s)
- David E Arnot
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health Sciences, University of Copenhagen, CSS Oester Farimagsgade 5, Copenhagen K, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), CSS Oester Farimagsgade 5, Copenhagen K, Denmark; Institute of Immunology and Infection Research, School of Biology, University of Edinburgh, Edinburgh, Scotland, United Kingdom
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24
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Wezena CA, Urscher M, Vince R, More SS, Deponte M. Hemolytic and antimalarial effects of tight-binding glyoxalase 1 inhibitors on the host-parasite unit of erythrocytes infected with Plasmodium falciparum. Redox Biol 2016; 8:348-53. [PMID: 26972115 PMCID: PMC4789335 DOI: 10.1016/j.redox.2016.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/22/2016] [Indexed: 12/18/2022] Open
Abstract
Glyoxalases prevent the formation of advanced glycation end products by converting glycolysis-derived methylglyoxal to d-lactate with the help of glutathione. Vander Jagt and colleagues previously showed that erythrocytes release about thirty times more d-lactate after infection with the human malaria parasite Plasmodium falciparum. Functional glyoxalases in the host-parasite unit might therefore be crucial for parasite survival. Here, we determined the antimalarial and hemolytic activity of two tight-binding glyoxalase inhibitors using infected and uninfected erythrocytes. In addition, we synthesized and analyzed a set of diester derivates of both tight-binding inhibitors resulting in up to threefold lower IC50 values and an altered methemoglobin formation and hemolytic activity depending on the type of ester. Inhibitor treatments of uninfected erythrocytes revealed an extremely slow inactivation of the host cell glyoxalase, irrespective of inhibitor modifications, and a potential dispensability of the host cell enzyme for parasite survival. Our study highlights the benefits and drawbacks of different esterifications of glutathione-derived inhibitors and demonstrates the suitability of glyoxalase inhibitors as a tool for deciphering the relevance and mode of action of different glyoxalase systems in a host-parasite unit.
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Affiliation(s)
- Cletus A Wezena
- Department of Parasitology, Ruprecht-Karls University, D-69120 Heidelberg, Germany
| | - Miriam Urscher
- Department of Parasitology, Ruprecht-Karls University, D-69120 Heidelberg, Germany
| | - Robert Vince
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Swati S More
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Marcel Deponte
- Department of Parasitology, Ruprecht-Karls University, D-69120 Heidelberg, Germany.
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25
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Ndam NT, Denoeud-Ndam L, Doritchamou J, Viwami F, Salanti A, Nielsen MA, Fievet N, Massougbodji A, Luty AJF, Deloron P. Protective Antibodies against Placental Malaria and Poor Outcomes during Pregnancy, Benin. Emerg Infect Dis 2016; 21:813-23. [PMID: 25898123 PMCID: PMC4412227 DOI: 10.3201/eid2105.141626] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Immunity requires a vaccine that inhibits binding of infected erythrocytes to chondroitin sulfate. Placental malaria is caused by Plasmodium falciparum–infected erythrocytes that bind to placental tissue. Binding is mediated by VAR2CSA, a parasite antigen coded by the var gene, which interacts with chondroitin sulfate A (CSA). Consequences include maternal anemia and fetal growth retardation. Antibody-mediated immunity to placental malaria is acquired during successive pregnancies, but the target of VAR2CSA-specific protective antibodies is unclear. We assessed VAR2CSA-specific antibodies in pregnant women and analyzed their relationships with protection against placental infection, preterm birth, and low birthweight. Antibody responses to the N-terminal region of VAR2CSA during early pregnancy were associated with reduced risks for infections and low birthweight. Among women infected during pregnancy, an increase in CSA binding inhibition was associated with reduced risks for placental infection, preterm birth, and low birthweight. These data suggest that antibodies against VAR2CSA N-terminal region mediate immunity to placental malaria and associated outcomes. Our results validate current vaccine development efforts with VAR2CSA N-terminal constructs.
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MESH Headings
- Adult
- Antibodies, Protozoan/blood
- Antibodies, Protozoan/immunology
- Antibody Specificity/immunology
- Antigens, Protozoan/immunology
- Benin/epidemiology
- Erythrocytes/immunology
- Erythrocytes/parasitology
- Female
- Follow-Up Studies
- Humans
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Infant
- Infant, Newborn
- Malaria/epidemiology
- Malaria/immunology
- Malaria/parasitology
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Patient Outcome Assessment
- Placenta/parasitology
- Plasmodium falciparum/immunology
- Pregnancy
- Pregnancy Complications, Parasitic/epidemiology
- Pregnancy Complications, Parasitic/immunology
- Pregnancy Complications, Parasitic/parasitology
- Pregnancy Outcome
- Protein Binding
- Risk Factors
- Young Adult
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26
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Contrasting Patterns of Serologic and Functional Antibody Dynamics to Plasmodium falciparum Antigens in a Kenyan Birth Cohort. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 23:104-16. [PMID: 26656119 PMCID: PMC4744923 DOI: 10.1128/cvi.00452-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 11/20/2015] [Indexed: 11/20/2022]
Abstract
IgG antibodies to Plasmodium falciparum are transferred from the maternal to fetal circulation during pregnancy, wane after birth, and are subsequently acquired in response to natural infection. We examined the dynamics of malaria antibody responses of 84 Kenyan infants from birth to 36 months of age by (i) serology, (ii) variant surface antigen (VSA) assay, (iii) growth inhibitory activity (GIA), and (iv) invasion inhibition assays (IIA) specific for merozoite surface protein 1 (MSP1) and sialic acid-dependent invasion pathway. Maternal antibodies in each of these four categories were detected in cord blood and decreased to their lowest level by approximately 6 months of age. Serologic antibodies to 3 preerythrocytic and 10 blood-stage antigens subsequently increased, reaching peak prevalence by 36 months. In contrast, antibodies measured by VSA, GIA, and IIA remained low even up to 36 months. Infants sensitized to P. falciparum in utero, defined by cord blood lymphocyte recall responses to malaria antigens, acquired antimalarial antibodies at the same rate as those who were not sensitized in utero, indicating that fetal exposure to malaria antigens did not affect subsequent infant antimalarial responses. Infants with detectable serologic antibodies at 12 months of age had an increased risk of P. falciparum infection during the subsequent 24 months. We conclude that serologic measures of antimalarial antibodies in children 36 months of age or younger represent biomarkers of malaria exposure rather than protection and that functional antibodies develop after 36 months of age in this population.
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27
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Nunes-Silva S, Dechavanne S, Moussiliou A, Pstrąg N, Semblat JP, Gangnard S, Tuikue-Ndam N, Deloron P, Chêne A, Gamain B. Beninese children with cerebral malaria do not develop humoral immunity against the IT4-VAR19-DC8 PfEMP1 variant linked to EPCR and brain endothelial binding. Malar J 2015; 14:493. [PMID: 26646943 PMCID: PMC4672576 DOI: 10.1186/s12936-015-1008-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 11/21/2015] [Indexed: 11/16/2022] Open
Abstract
Background Malaria is still one of the most prevalent infectious diseases in the world. Sequestration of infected erythrocytes (IEs) is the prime mediator of disease. Cytoadhesion of IEs is mediated by members of the highly diverse Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). A restricted sub-set of var genes encoding for PfEMP1s possessing the domain cassettes DC8 and DC13 were found to bind to the endothelial protein C receptor (EPCR). These var genes were shown to be highly expressed by parasites from patients with severe malaria clinical outcomes compared to those from patients with uncomplicated symptoms. Methods In order to further study the molecular mechanisms underlying DC8/DC13 expressing IEs adhesion to EPCR, a method was developed to produce highly pure recombinant EPCR. The IT4 parasite strain was selected on either anti-IT4-VAR19 purified IgG, EPCR or human brain endothelial cell line and their var gene expression profiles as well as their binding phenotypes were compared. The N-terminal region of IT4-VAR19 comprising a full-length DC8 cassette as well as the single EPCR binding CIDRα1.1 domain were also produced, and their immune recognition (IgG) was assessed using plasma samples from Beninese children presenting acute mild malaria, severe malaria or cerebral malaria at the time of their admission to the clinic, and from convalescent-phase plasma collected 30 days after anti-malarial treatment. Results The multi-domain VAR19-NTS-DBLγ6 binds to EPCR with a greater affinity than the CIDRα1.1 domain alone and this study also demonstrates that VAR19-NTS-DBLγ6 binding to the EPCR-expressing endothelial cell line (HBEC5i) is more pronounced than that of the CIDRα1.1 domain alone. IT4-VAR19 represents the preferentially expressed-PfEMP1 when FCR3-IEs are selected based on their capability to bind EPCR. Notably, no significant difference in the levels of antibodies towards IT4-VAR19 antigens was observed within all clinical groups between plasma samples collected during the acute malaria phase compared to samples collected 30 days after anti-malaria treatment. Conclusions These data indicate that even being the preferentially selected IT4-EPCR-binding variant, the IT4-VAR19-DC8 region does not appear to be associated with the acquisition of antibodies during a single severe paediatric malaria episode in Benin. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1008-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sofia Nunes-Silva
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Sébastien Dechavanne
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Azizath Moussiliou
- Laboratory of Excellence GR-Ex, Paris, France. .,Institut de Recherche pour le développement, UMR_216, Mère et enfant face aux infections tropicales, Paris, France. .,Faculté de pharmacie, PRES Sorbonne Paris Cité, Paris, France.
| | - Natalia Pstrąg
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Jean-Philippe Semblat
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Stéphane Gangnard
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Nicaise Tuikue-Ndam
- Laboratory of Excellence GR-Ex, Paris, France. .,Institut de Recherche pour le développement, UMR_216, Mère et enfant face aux infections tropicales, Paris, France. .,Faculté de pharmacie, PRES Sorbonne Paris Cité, Paris, France.
| | - Philippe Deloron
- Laboratory of Excellence GR-Ex, Paris, France. .,Institut de Recherche pour le développement, UMR_216, Mère et enfant face aux infections tropicales, Paris, France. .,Faculté de pharmacie, PRES Sorbonne Paris Cité, Paris, France.
| | - Arnaud Chêne
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
| | - Benoît Gamain
- Inserm UMR_1134, Paris, France. .,Université Paris Diderot, Sorbonne Paris Cité, UMR_S1134, Paris, France. .,Institut National de la Transfusion Sanguine, 6 rue Alexandre Cabanel, 75015, Paris, France. .,Laboratory of Excellence GR-Ex, Paris, France.
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28
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Külzer S, Bittl V, Przyborski JM. Fractionation of Plasmodium-infected human red blood cells to study protein trafficking. Methods Mol Biol 2015; 1270:71-80. [PMID: 25702109 DOI: 10.1007/978-1-4939-2309-0_5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Subcellular fractionation is a valuable tool to follow protein traffic between cellular compartments. Here we detail a procedure for fractionating erythrocytes infected with the human malaria parasite P. falciparum using the bacterial pore-forming protein Streptolysin O (SLO). Additionally we describe an experimental protocol to determine protein topology by carrying out a protease protection assay on SLO-lysed infected erythrocytes.
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Affiliation(s)
- Simone Külzer
- Research School of Biology, The Australian National University, Canberra, Australia
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29
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Bianchin A, Bell A, Chubb AJ, Doolan N, Leneghan D, Stavropoulos I, Shields DC, Mooney C. Design and evaluation of antimalarial peptides derived from prediction of short linear motifs in proteins related to erythrocyte invasion. PLoS One 2015; 10:e0127383. [PMID: 26039561 PMCID: PMC4454681 DOI: 10.1371/journal.pone.0127383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 04/15/2015] [Indexed: 11/19/2022] Open
Abstract
The purpose of this study was to investigate the blood stage of the malaria causing parasite, Plasmodium falciparum, to predict potential protein interactions between the parasite merozoite and the host erythrocyte and design peptides that could interrupt these predicted interactions. We screened the P. falciparum and human proteomes for computationally predicted short linear motifs (SLiMs) in cytoplasmic portions of transmembrane proteins that could play roles in the invasion of the erythrocyte by the merozoite, an essential step in malarial pathogenesis. We tested thirteen peptides predicted to contain SLiMs, twelve of them palmitoylated to enhance membrane targeting, and found three that blocked parasite growth in culture by inhibiting the initiation of new infections in erythrocytes. Scrambled peptides for two of the most promising peptides suggested that their activity may be reflective of amino acid properties, in particular, positive charge. However, one peptide showed effects which were stronger than those of scrambled peptides. This was derived from human red blood cell glycophorin-B. We concluded that proteome-wide computational screening of the intracellular regions of both host and pathogen adhesion proteins provides potential lead peptides for the development of anti-malarial compounds.
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Affiliation(s)
- Alessandra Bianchin
- Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- Complex and Adaptive Systems Laboratory, University College Dublin, Dublin, Ireland
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Angus Bell
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Anthony J. Chubb
- Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- Complex and Adaptive Systems Laboratory, University College Dublin, Dublin, Ireland
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Nathalie Doolan
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Darren Leneghan
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Ilias Stavropoulos
- Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- Complex and Adaptive Systems Laboratory, University College Dublin, Dublin, Ireland
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Denis C. Shields
- Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- Complex and Adaptive Systems Laboratory, University College Dublin, Dublin, Ireland
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
| | - Catherine Mooney
- Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Dublin, Ireland
- Complex and Adaptive Systems Laboratory, University College Dublin, Dublin, Ireland
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
- * E-mail:
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30
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Tan J, Bull PC. Agglutination Assays of the Plasmodium falciparum-Infected Erythrocyte. Methods Mol Biol 2015; 1325:115-129. [PMID: 26450384 PMCID: PMC6624126 DOI: 10.1007/978-1-4939-2815-6_10] [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] [Indexed: 06/05/2023]
Abstract
The agglutination assay is used to determine the ability of antibodies to recognize parasite variant antigens on the surface of Plasmodium falciparum-infected erythrocytes. In this technique, infected erythrocytes are selectively labelled with a DNA-binding fluorescent dye and mixed with antibodies of interest to allow antibody-surface antigen binding. Recognition of surface antigens by the antibodies can result in the formation of agglutinates containing multiple parasite-infected erythrocytes. These can be viewed and quantified using a fluorescence microscope.
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Affiliation(s)
- Joshua Tan
- KEMRI-Wellcome Trust Research Programme, 230-80108, Kilifi, Kenya
- Centre for Tropical Medicine, Nuffield Department of Medicine, Oxford University, Oxford, OX3 7LJ, UK
| | - Peter C Bull
- KEMRI-Wellcome Trust Research Programme, 230-80108, Kilifi, Kenya.
- Centre for Tropical Medicine, Nuffield Department of Medicine, Oxford University, Oxford, OX3 7LJ, UK.
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31
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Llama immunization with full-length VAR2CSA generates cross-reactive and inhibitory single-domain antibodies against the DBL1X domain. Sci Rep 2014; 4:7373. [PMID: 25487735 PMCID: PMC5376981 DOI: 10.1038/srep07373] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022] Open
Abstract
VAR2CSA stands today as the leading vaccine candidate aiming to protect future pregnant women living in malaria endemic areas against the severe clinical outcomes of pregnancy associated malaria (PAM). The rational design of an efficient VAR2CSA-based vaccine relies on a profound understanding of the molecular interactions associated with P. falciparum infected erythrocyte sequestration in the placenta. Following immunization of a llama with the full-length VAR2CSA recombinant protein, we have expressed and characterized a panel of 19 nanobodies able to recognize the recombinant VAR2CSA as well as the surface of erythrocytes infected with parasites originating from different parts of the world. Domain mapping revealed that a large majority of nanobodies targeted DBL1X whereas a few of them were directed towards DBL4ε, DBL5ε and DBL6ε. One nanobody targeting the DBL1X was able to recognize the native VAR2CSA protein of the three parasite lines tested. Furthermore, four nanobodies targeting DBL1X reproducibly inhibited CSA adhesion of erythrocytes infected with the homologous NF54-CSA parasite strain, providing evidences that DBL1X domain is part or close to the CSA binding site. These nanobodies could serve as useful tools to identify conserved epitopes shared between different variants and to characterize the interactions between VAR2CSA and CSA.
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Immune characterization of Plasmodium falciparum parasites with a shared genetic signature in a region of decreasing transmission. Infect Immun 2014; 83:276-85. [PMID: 25368109 DOI: 10.1128/iai.01979-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
As the intensity of malaria transmission has declined, Plasmodium falciparum parasite populations have displayed decreased clonal diversity resulting from the emergence of many parasites with common genetic signatures (CGS). We have monitored such CGS parasite clusters from 2006 to 2013 in Thiès, Senegal, using the molecular barcode. The first, and one of the largest observed clusters of CGS parasites, was present in 24% of clinical isolates in 2008, declined to 3.4% of clinical isolates in 2009, and then disappeared. To begin to explore the relationship between the immune responses of the population and the emergence and decline of specific parasite genotypes, we have determined whether antibodies to CGS parasites correlate with their prevalence. We measured (i) antibodies capable of inhibiting parasite growth in culture and (ii) antibodies recognizing the surfaces of infected erythrocytes (RBCs). IgG obtained from volunteers in 2009 showed increased reactivity to the surfaces of CGS-parasitized erythrocytes over IgG from 2008. Since P. falciparum EMP-1 (PfEMP-1) is a major variant surface antigen, we used var Ups quantitative reverse transcription-PCR (qRT-PCR) and sequencing with degenerate DBL1α domain primers to characterize the var genes expressed by CGS parasites after short-term in vitro culture. CGS parasites show upregulation of UpsA var genes and 2-cysteine-containing PfEMP-1 molecules and express the same dominant var transcript. Our work indicates that the CGS parasites in this cluster express similar var genes, more than would be expected by chance in the population, and that there is year-to-year variation in immune recognition of surface antigens on CGS parasite-infected erythrocytes. This study lays the groundwork for detailed investigations of the mechanisms driving the expansion or contraction of specific parasite clones in the population.
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High-throughput tri-colour flow cytometry technique to assess Plasmodium falciparum parasitaemia in bioassays. Malar J 2014; 13:412. [PMID: 25331683 PMCID: PMC4213491 DOI: 10.1186/1475-2875-13-412] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2014] [Accepted: 10/09/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Unbiased flow cytometry-based methods have become the technique of choice in many laboratories for high-throughput, accurate assessments of malaria parasites in bioassays. A method to quantify live parasites based on mitotracker red CMXRos was recently described but consistent distinction of early ring stages of Plasmodium falciparum from uninfected red blood cells (uRBC) remains a challenge. METHODS Here, a high-throughput, three-parameter (tri-colour) flow cytometry technique based on mitotracker red dye, the nucleic acid dye coriphosphine O (CPO) and the leucocyte marker CD45 for enumerating live parasites in bioassays was developed. The technique was applied to estimate the specific growth inhibition index (SGI) in the antibody-dependent cellular inhibition (ADCI) assay and compared to parasite quantification by microscopy and mitotracker red staining. The Bland-Altman analysis was used to compare biases between SGI estimated by the tri-colour staining technique, mitotracker red and by microscopy. RESULTS CPO allowed a better separation between early rings and uRBCs compared to mitotracker red resulting in a more accurate estimate of total parasitaemia. The tri-colour technique is rapid, cost effective and robust with comparable sensitivity to microscopy and capable of discriminating between live and dead and/or compromised parasites. Staining for CD45 improved parasitaemia estimates in ADCI assay since high numbers of leucocytes interfered with the accurate identification of parasitized RBC. The least bias (-1.60) in SGI was observed between the tri-colour and microscopy. CONCLUSION An improved methodology for high-throughput assessment of P. falciparum parasitaemia under culture conditions that could be useful in different bioassays, including ADCI and growth inhibition assays has been developed.
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High guanidinium permeability reveals dehydration-dependent ion selectivity in the plasmodial surface anion channel. BIOMED RESEARCH INTERNATIONAL 2014; 2014:741024. [PMID: 25243175 PMCID: PMC4160636 DOI: 10.1155/2014/741024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/19/2014] [Accepted: 07/23/2014] [Indexed: 11/17/2022]
Abstract
Malaria parasites grow within vertebrate erythrocytes and increase host cell permeability to access nutrients from plasma. This increase is mediated by the plasmodial surface anion channel (PSAC), an unusual ion channel linked to the conserved clag gene family. Although PSAC recognizes and transports a broad range of uncharged and charged solutes, it must efficiently exclude the small Na+ ion to maintain infected cell osmotic stability. Here, we examine possible mechanisms for this remarkable solute selectivity. We identify guanidinium as an organic cation with high permeability into human erythrocytes infected with Plasmodium falciparum, but negligible uptake by uninfected cells. Transport characteristics and pharmacology indicate that this uptake is specifically mediated by PSAC. The rank order of organic and inorganic cation permeabilities suggests cation dehydration as the rate-limiting step in transport through the channel. The high guanidinium permeability of infected cells also allows rapid and stringent synchronization of parasite cultures, as required for molecular and cellular studies of this pathogen. These studies provide important insights into how nutrients and ions are transported via PSAC, an established target for antimalarial drug development.
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Roobsoong W, Maher SP, Rachaphaew N, Barnes SJ, Williamson KC, Sattabongkot J, Adams JH. A rapid sensitive, flow cytometry-based method for the detection of Plasmodium vivax-infected blood cells. Malar J 2014; 13:55. [PMID: 24528780 PMCID: PMC3942109 DOI: 10.1186/1475-2875-13-55] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 01/22/2014] [Indexed: 11/15/2022] Open
Abstract
Background Plasmodium vivax preferentially infects Duffy-positive reticulocytes and infections typically have few parasite-infected cells in the peripheral circulation. These features complicate detection and quantification by flow cytometry (FC) using standard nucleic acid-based staining methods. A simple antibody-based FC method was developed for rapid parasite detection along with simultaneous detection of other parasite and erythrocyte markers. Methods Clinical samples were collected from patients diagnosed with P. vivax at a district Malaria Clinic in Kanchanaburi, Thailand. One μL of infected blood was washed, fixed, stained with a Plasmodium pan-specific anti-PfBiP antibody conjugated with Alexa Fluor 660, and analysed by FC. Additional primary conjugated antibodies for stage-specific markers of P. vivax for late trophozoite-early schizonts (MSP1-Alexa Fluor 660), late-stage schizonts (DBP-Alexa Fluor 555), and sexual stages (Pvs16) were used to differentiate intra-erythrocytic developmental stages. Results The percentages of P. vivax-infected cells determined by the FC method and manually by microscopic examination of Giemsa-stained thick blood smears were positively correlated by Spearman’s rank correlation coefficient (R2 = 0.93843) from 0.001 to 1.00% P. vivax-infected reticulocytes. Conclusions The FC-based method is a simple, robust, and efficient method for detecting P. vivax-infected reticulocytes.
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Affiliation(s)
| | | | | | | | | | | | - John H Adams
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA.
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Adukpo S, Kusi KA, Ofori MF, Tetteh JKA, Amoako-Sakyi D, Goka BQ, Adjei GO, Edoh DA, Akanmori BD, Gyan BA, Dodoo D. High plasma levels of soluble intercellular adhesion molecule (ICAM)-1 are associated with cerebral malaria. PLoS One 2013; 8:e84181. [PMID: 24386348 PMCID: PMC3873986 DOI: 10.1371/journal.pone.0084181] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 11/12/2013] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Cerebral malaria (CM) is responsible for most of the malaria-related deaths in children in sub-Saharan Africa. Although, not well understood, the pathogenesis of CM involves parasite and host factors which contribute to parasite sequestration through cytoadherence to the vascular endothelium. Cytoadherence to brain microvasculature is believed to involve host endothelial receptor, CD54 or intercellular adhesion molecule (ICAM)-1, while other receptors such as CD36 are generally involved in cytoadherence of parasites in other organs. We therefore investigated the contributions of host ICAM-1 expression and levels of antibodies against ICAM-1 binding variant surface antigen (VSA) on parasites to the development of CM. METHODOLOGY/PRINCIPAL FINDINGS Paediatric malaria patients, 0.5 to 13 years were recruited and grouped into CM and uncomplicated malaria (UM) patients, based on well defined criteria. Standardized ELISA protocol was used to measure soluble ICAM-1 (sICAM-1) levels from acute plasma samples. Levels of IgG to CD36- or ICAM-1-binding VSA were measured by flow cytometry during acute and convalescent states. Wilcoxon sign rank-test analysis to compare groups revealed association between sICAM-1 levels and CM (p<0.0037). Median levels of antibodies to CD36-binding VSA were comparable in the two groups at the time of admission and 7 days after treatment was initiated (p>0.05). Median levels of antibodies to CD36-binding VSAs were also comparable between acute and convalescent samples within any patient group. Median levels of antibodies to ICAM-1-binding VSAs were however significantly lower at admission time than during recovery in both groups. CONCLUSIONS/SIGNIFICANCE High levels of sICAM-1 were associated with CM, and the sICAM-1 levels may reflect expression levels of the membrane bound form. Anti-VSA antibody levels to ICAM-binding parasites was more strongly associated with both UM and CM than antibodies to CD36 binding parasites. Thus, increasing host sICAM-1 levels were associated with CM whilst antibodies to parasite expressing non-ICAM-1-binding VSAs were not.
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Affiliation(s)
- Selorme Adukpo
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
- Department of Animal Biology and Conservation Science, University of Ghana, Legon, Accra, Ghana
- * E-mail:
| | - Kwadwo A. Kusi
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Michael F. Ofori
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - John K. A. Tetteh
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Daniel Amoako-Sakyi
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Bamenla Q. Goka
- Department of Child Health, University of Ghana Medical School, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - George O. Adjei
- Department of Child Health, University of Ghana Medical School, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Dominic A. Edoh
- Department of Animal Biology and Conservation Science, University of Ghana, Legon, Accra, Ghana
| | - Bartholomew D. Akanmori
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Ben A. Gyan
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
| | - Daniel Dodoo
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana
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Zeituni AE, Miura K, Diakite M, Doumbia S, Moretz SE, Diouf A, Tullo G, Lopera-Mesa TM, Bess CD, Mita-Mendoza NK, Anderson JM, Fairhurst RM, Long CA. Effects of age, hemoglobin type and parasite strain on IgG recognition of Plasmodium falciparum-infected erythrocytes in Malian children. PLoS One 2013; 8:e76734. [PMID: 24124591 PMCID: PMC3790723 DOI: 10.1371/journal.pone.0076734] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 08/28/2013] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Naturally-acquired antibody responses to antigens on the surface of Plasmodium falciparum-infected red blood cells (iRBCs) have been implicated in antimalarial immunity. To profile the development of this immunity, we have been studying a cohort of Malian children living in an area with intense seasonal malaria transmission. METHODOLOGY/PRINCIPAL FINDINGS We collected plasma from a sub-cohort of 176 Malian children aged 3-11 years, before (May) and after (December) the 2009 transmission season. To measure the effect of hemoglobin (Hb) type on antibody responses, we enrolled age-matched HbAA, HbAS and HbAC children. To quantify antibody recognition of iRBCs, we designed a high-throughput flow cytometry assay to rapidly test numerous plasma samples against multiple parasite strains. We evaluated antibody reactivity of each plasma sample to 3 laboratory-adapted parasite lines (FCR3, D10, PC26) and 4 short-term-cultured parasite isolates (2 Malian and 2 Cambodian). 97% of children recognized ≥1 parasite strain and the proportion of IgG responders increased significantly during the transmission season for most parasite strains. Both strain-specific and strain-transcending IgG responses were detected, and varied by age, Hb type and parasite strain. In addition, the breadth of IgG responses to parasite strains increased with age in HbAA, but not in HbAS or HbAC, children. CONCLUSIONS/SIGNIFICANCE Our assay detects both strain-specific and strain-transcending IgG responses to iRBCs. The magnitude and breadth of these responses varied not only by age, but also by Hb type and parasite strain used. These findings indicate that studies of acquired humoral immunity should account for Hb type and test large numbers of diverse parasite strains.
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Affiliation(s)
- Amir E. Zeituni
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Mahamadou Diakite
- Faculty of Medicine, Pharmacy and Odontostomatology, University of Bamako, Bamako, Mali
| | - Saibou Doumbia
- Faculty of Medicine, Pharmacy and Odontostomatology, University of Bamako, Bamako, Mali
| | - Samuel E. Moretz
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Gregory Tullo
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Tatiana M. Lopera-Mesa
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Cameron D. Bess
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Neida K. Mita-Mendoza
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- Departamento de Biomedicina Molecular, Centro de Investigación y Estudios Avanzados, México City, México
| | - Jennifer M. Anderson
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Rick M. Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail:
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El Chaar M, Atwal S, Freimanis GL, Dinko B, Sutherland CJ, Allain JP. Inactivation of Plasmodium falciparum in whole blood by riboflavin plus irradiation. Transfusion 2013; 53:3174-83. [PMID: 23656538 DOI: 10.1111/trf.12235] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Revised: 02/01/2013] [Accepted: 02/04/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND Malaria parasites are frequently transmitted by unscreened blood transfusions in Africa. Pathogen reduction methods in whole blood would thus greatly improve blood safety. We aimed to determine the efficacy of riboflavin plus irradiation for treatment of whole blood infected with Plasmodium falciparum. STUDY DESIGN AND METHODS Blood was inoculated with 10(4) or 10(5) parasites/mL and riboflavin treated with or without ultraviolet (UV) irradiation (40-160 J/mL red blood cells [mL(RBCs)]). Parasite genome integrity was assessed by quantitative amplification inhibition assays, and P. falciparum viability was monitored in vitro. RESULTS Riboflavin alone did not affect parasite genome integrity or parasite viability. Application of UV after riboflavin treatment disrupted parasite genome integrity, reducing polymerase-dependent amplification by up to 2 logs (99%). At 80 J/mL(RBCs), riboflavin plus irradiation prevented recovery of viable parasites in vitro for 2 weeks, whereas untreated controls typically recovered to approximately 2% parasitemia after 4 days of in vitro culture. Exposure of blood to 160 J/mL(RBCs) was not associated with significant hemolysis. CONCLUSIONS Riboflavin plus irradiation treatment of whole blood damages parasite genomes and drastically reduces P. falciparum viability in vitro. In the absence of suitable malaria screening assays, parasite inactivation should be investigated for prevention of transfusion-transmitted malaria in highly endemic areas.
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Affiliation(s)
- Mira El Chaar
- Department of Haematology, University of Cambridge, Cambridge, United Kingdom; Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom; HPA Malaria Reference Laboratory, London School of Hygiene & Tropical Medicine, London, United Kingdom; Faculty of Health Sciences, University of Balamand, Beirut, Lebanon
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Lopera-Mesa TM, Doumbia S, Chiang S, Zeituni AE, Konate DS, Doumbouya M, Keita AS, Stepniewska K, Traore K, Diakite SAS, Ndiaye D, Sa JM, Anderson JM, Fay MP, Long CA, Diakite M, Fairhurst RM. Plasmodium falciparum clearance rates in response to artesunate in Malian children with malaria: effect of acquired immunity. J Infect Dis 2013; 207:1655-63. [PMID: 23448727 PMCID: PMC3636783 DOI: 10.1093/infdis/jit082] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Background. Artemisinin resistance, a long parasite clearance half-life in response to artemisinin, has been described in patients with Plasmodium falciparum malaria in southeast Asia. Few baseline half-lives have been reported from Africa, where artemisinins were recently introduced. Methods. We treated P. falciparum malaria in 215 Malian children aged 0.5–15 years with artesunate (0, 24, 48 hours) and amodiaquine (72, 96, 120 hours). We estimated half-life by measuring parasite density every 6 hours until undetectable and evaluated the effects of age, sex, ethnicity, and red blood cell (RBC) polymorphisms on half-life. We quantified the proportion of parasitized RBCs recognized by autologous immunoglobulin G (IgG). Results. The geometric mean half-life was 1.9 hours (95% confidence interval, 1.8–2.0) and did not correlate with parasite ex vivo susceptibility to artemisinins. In a linear model accounting for host factors, half-life decreased by 4.1 minutes for every 1-year increase in age. The proportion of parasitized RBCs recognized by IgG correlated inversely with half-life (r = −0.475; P = .0006). Conclusions. Parasite clearance in response to artesunate is faster in Mali than in southeast Asia. IgG responses to parasitized RBCs shorten half-life and may influence this parameter in areas where age is not an adequate surrogate of immunity and correlates of parasite-clearing immunity have not been identified. Clinical Trials Registration. NCT00669084.
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Affiliation(s)
- Tatiana M Lopera-Mesa
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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A method for positive and negative selection of Plasmodium falciparum platelet-mediated clumping parasites and investigation of the role of CD36. PLoS One 2013; 8:e55453. [PMID: 23405153 PMCID: PMC3566186 DOI: 10.1371/journal.pone.0055453] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2012] [Accepted: 12/29/2012] [Indexed: 01/08/2023] Open
Abstract
Platelet-mediated clumping of Plasmodium falciparum infected erythrocytes (IEs) is a frequently observed parasite adhesion phenotype. The importance of clumping in severe malaria and the molecular mechanisms behind this phenomenon are incompletely understood. Three platelet surface molecules have previously been identified as clumping receptors: CD36, globular C1q receptor (gC1qR/HABP1/p32), and P-selectin (CD62P), but the parasite ligands mediating this phenotype are unknown. The aim of this work was to develop a selection method to facilitate investigations of the molecular mechanisms of clumping in selected P. falciparum lines. Magnetic beads coated with anti-platelet antibodies were used to positively and negatively select clumping IEs from P. falciparum strains IT, HB3, 3D7 and Dd2. Clumping in all four positively selected parasite lines was abolished by antibodies to CD36, but was not affected by antibodies to gC1qR or P-selectin. Clumping positive lines showed significantly higher binding to CD36 than clumping negative lines in flow adhesion assays (strains IT, HB3 and 3D7, p<0.05 for all strains, paired t test) and static assays (strain Dd2, p<0.0001 paired t test). However, clumping negative lines IT, HB3 and 3D7 did show some binding to CD36 under flow conditions, indicating that CD36-binding is not sufficient for clumping. These data show that CD36-dependent clumping positive and negative lines can easily be selected from P. falciparum laboratory strains. CD36-binding is necessary but not sufficient for clumping, and the molecular differences between clumping positive and negative parasite lines responsible for the phenotype require further investigation.
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Mwakalinga SB, Wang CW, Bengtsson DC, Turner L, Dinko B, Lusingu JP, Arnot DE, Sutherland CJ, Theander TG, Lavstsen T. Expression of a type B RIFIN in Plasmodium falciparum merozoites and gametes. Malar J 2012; 11:429. [PMID: 23259643 PMCID: PMC3544569 DOI: 10.1186/1475-2875-11-429] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 12/19/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The ability of Plasmodium falciparum to undergo antigenic variation, by switching expression among protein variants encoded by multigene families, such as var, rif and stevor, is key to the survival of this parasite in the human host. The RIFIN protein family can be divided into A and B types based on the presence or absence of a 25 amino acid motif in the semi-conserved domain. A particular type B RIFIN, PF13_0006, has previously been shown to be strongly transcribed in the asexual and sexual stages of P. falciparum in vitro. METHODS Antibodies to recombinant PF13_0006 RIFIN were used in immunofluorescence and confocal imaging of 3D7 parasites throughout the asexual reproduction and sexual development to examine the expression of PF13_0006. Furthermore, reactivity to recombinant PF13_0006 was measured in plasma samples collected from individuals from both East and West African endemic areas. RESULTS The PF13_0006 RIFIN variant appeared expressed by both released merozoites and gametes after emergence. 7.4% and 12.1% of individuals from East and West African endemic areas, respectively, carry plasma antibodies that recognize recombinant PF13_0006, where the antibody responses were more common among older children. CONCLUSIONS The stage specificity of PF13_0006 suggests that the diversity of RIFIN variants has evolved to provide multiple specialized functions in different stages of the parasite life cycle. These data also suggest that RIFIN variants antigenically similar to PF13_0006 occur in African parasite populations.
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Affiliation(s)
- Steven B Mwakalinga
- Centre for Medical Parasitology, Department of International Health, Immunology, and Microbiology, University of Copenhagen, Denmark
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Tibúrcio M, Silvestrini F, Bertuccini L, Sander AF, Turner L, Lavstsen T, Alano P. Early gametocytes of the malaria parasite Plasmodium falciparum specifically remodel the adhesive properties of infected erythrocyte surface. Cell Microbiol 2012; 15:647-59. [PMID: 23114006 DOI: 10.1111/cmi.12062] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2012] [Revised: 10/11/2012] [Accepted: 10/24/2012] [Indexed: 11/27/2022]
Abstract
In Plasmodium falciparum infections the parasite transmission stages, the gametocytes, mature in 10 days sequestered in internal organs. Recent studies suggest that cell mechanical properties rather than adhesive interactions play a role in sequestration during gametocyte maturation. It remains instead obscure how sequestration is established, and how the earliest sexual stages, morphologically similar to asexual trophozoites, modify the infected erythrocytes and their cytoadhesive properties at the onset of gametocytogenesis. Here, purified P. falciparum early gametocytes were used to ultrastructurally and biochemically analyse parasite-induced modifications on the red blood cell surface and to measure their functional consequences on adhesion to human endothelial cells. This work revealed that stage I gametocytes are able to deform the infected erythrocytes like asexual parasites, but do not modify its surface with adhesive 'knob' structures and associated proteins. Reduced levels of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesins are exposed on the red blood cell surface by these parasites, and the expression of the var gene family, which encodes 50-60 variants of PfEMP1, is dramatically downregulated in the transition from asexual development to gametocytogenesis. Cytoadhesion assays show that such gene expression changes and host cell surface modifications functionally result in the inability of stage I gametocytes to bind the host ligands used by the asexual parasite to bind endothelial cells. In conclusion, these results identify specific differences in molecular and cellular mechanisms of host cell remodelling and in adhesive properties, leading to clearly distinct host parasite interplays in the establishment of sequestration of stage I gametocytes and of asexual trophozoites.
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Affiliation(s)
- Marta Tibúrcio
- Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, viale Regina Elena 299, 00161, Rome, Italy
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Ajua A, Engleitner T, Esen M, Theisen M, Issifou S, Mordmüller B. A flow cytometry-based workflow for detection and quantification of anti-plasmodial antibodies in vaccinated and naturally exposed individuals. Malar J 2012; 11:367. [PMID: 23130649 PMCID: PMC3545855 DOI: 10.1186/1475-2875-11-367] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 10/30/2012] [Indexed: 11/14/2022] Open
Abstract
Background Antibodies play a central role in naturally acquired immunity against Plasmodium falciparum. Current assays to detect anti-plasmodial antibodies against native antigens within their cellular context are prone to bias and cannot be automated, although they provide important information about natural exposure and vaccine immunogenicity. A novel, cytometry-based workflow for quantitative detection of anti-plasmodial antibodies in human serum is presented. Methods Fixed red blood cells (RBCs), infected with late stages of P. falciparum were utilized to detect malaria-specific antibodies by flow cytometry with subsequent automated data analysis. Available methods for data-driven analysis of cytometry data were assessed and a new overlap subtraction algorithm (OSA) based on open source software was developed. The complete workflow was evaluated using sera from two GMZ2 malaria vaccine trials in semi-immune adults and pre-school children residing in a malaria endemic area. Results Fixation, permeabilization, and staining of infected RBCs were adapted for best operation in flow cytometry. As asexual blood-stage vaccine candidates are designed to induce antibody patterns similar to those in semi-immune adults, serial dilutions of sera from heavily exposed individuals were compared to naïve controls to determine optimal antibody dilutions. To eliminate investigator effects introduced by manual gating, a non-biased algorithm (OSA) for data-driven gating was developed. OSA-derived results correlated well with those obtained by manual gating (r between 0.79 and 0.99) and outperformed other model-driven gating methods. Bland-Altman plots confirmed the agreement of manual gating and OSA-derived results. A 1.33-fold increase (p=0.003) in the number of positive cells after vaccination in a subgroup of pre-school children vaccinated with 100 μg GMZ2 was present and in vaccinated adults from the same region we measured a baseline-corrected 1.23-fold, vaccine-induced increase in mean fluorescence intensity of positive cells (p=0.03). Conclusions The current workflow advances detection and quantification of anti-plasmodial antibodies through improvement of a bias-prone, low-throughput to an unbiased, semi-automated, scalable method. In conclusion, this work presents a novel method for immunofluorescence assays in malaria research.
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Affiliation(s)
- Anthony Ajua
- Institute of Tropical Medicine, University of Tübingen, Wilhelmstraße 27, Tübingen D-72074, Germany
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Jogdand PS, Singh SK, Christiansen M, Dziegiel MH, Singh S, Theisen M. Flow cytometric readout based on Mitotracker Red CMXRos staining of live asexual blood stage malarial parasites reliably assesses antibody dependent cellular inhibition. Malar J 2012; 11:235. [PMID: 22818754 PMCID: PMC3418546 DOI: 10.1186/1475-2875-11-235] [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: 06/01/2012] [Accepted: 07/20/2012] [Indexed: 11/10/2022] Open
Abstract
Background Functional in vitro assays could provide insights into the efficacy of malaria vaccine candidates. For estimating the anti-parasite effect induced by a vaccine candidate, an accurate determination of live parasite count is an essential component of most in vitro bioassays. Although traditionally parasites are counted microscopically, a faster, more accurate and less subjective method for counting parasites is desirable. In this study mitochondrial dye (Mitotracker Red CMXRos) was used for obtaining reliable live parasite counts through flow cytometry. Methods Both asynchronous and tightly synchronized asexual blood stage cultures of Plasmodium falciparum were stained with CMXRos and subjected to detection by flow cytometry and fluorescence microscopy. The parasite counts obtained by flow cytometry were compared to standard microscopic counts obtained through examination of Giemsa-stained thin smears. A comparison of the ability of CMXRos to stain live and compromised parasites (induced by either medium starvation or by anti-malarial drug treatment) was carried out. Finally, parasite counts obtained by CMXRos staining through flow cytometry were used to determine specific growth inhibition index (SGI) in an antibody-dependent cellular inhibition (ADCI) assay. Results Mitotracker Red CMXRos can reliably detect live intra-erythrocytic stages of P. falciparum. Comparison between staining of live with compromised parasites shows that CMXRos predominantly stains live parasites with functional mitochondria. Parasite counts obtained by CMXRos staining and flow cytometry were highly reproducible and can reliably determine the ability of IgG from hyper-immune individuals to inhibit parasite growth in presence of monocytes in ADCI assay. Further, a dose-dependent parasite growth inhibitory effect could be detected for both total IgG purified from hyper-immune sera and affinity purified IgGs against the N-terminal non-repeat region of GLURP in ADCI assays coupled with determination of parasite counts through CMXRos staining and flow cytometry. Conclusions A flow cytometry method based on CMXRos staining for detection of live parasite populations has been optimized. This is a rapid and sensitive method with high inter-assay reproducibility which can reliably determine the anti-parasite effect mediated by antibodies in functional in vitro assays such as ADCI assay.
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Affiliation(s)
- Prajakta S Jogdand
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
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Wang CW, Lavstsen T, Bengtsson DC, Magistrado PA, Berger SS, Marquard AM, Alifrangis M, Lusingu JP, Theander TG, Turner L. Evidence for in vitro and in vivo expression of the conserved VAR3 (type 3) plasmodium falciparum erythrocyte membrane protein 1. Malar J 2012; 11:129. [PMID: 22533832 PMCID: PMC3407477 DOI: 10.1186/1475-2875-11-129] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Accepted: 04/25/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Members of the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) adhesion antigen family are major contributors to the pathogenesis of P. falciparum malaria infections. The PfEMP1-encoding var genes are among the most diverse sequences in nature, but three genes, var1, var2csa and var3 are found conserved in most parasite genomes. The most severe forms of malaria disease are caused by parasites expressing a subset of antigenically conserved PfEMP1 variants. Thus the ubiquitous and conserved VAR3 PfEMP1 is of particular interest to the research field. Evidence of VAR3 expression on the infected erythrocyte surface has never been presented, and var3 genes have been proposed to be transcribed and expressed differently from the rest of the var gene family members. METHODS In this study, parasites expressing VAR3 PfEMP1 were generated using anti-VAR3 antibodies and the var transcript and PfEMP1 expression profiles of the generated parasites were investigated. The IgG reactivity by plasma from children living in malaria-endemic Tanzania was tested to parasites and recombinant VAR3 protein. Parasites from hospitalized children were isolated and the transcript level of var3 was investigated. RESULTS Var3 is transcribed and its protein product expressed on the surface of infected erythrocytes. The VAR3-expressing parasites were better recognized by children´s IgG than a parasite line expressing a Group B var gene. Two in 130 children showed increased recognition of parasites expressing VAR3 and to the recombinant VAR3 protein after a malaria episode and the isolated parasites showed high levels of var3 transcripts. CONCLUSIONS Collectively, the presented data suggest that var3 is transcribed and its protein product expressed on the surface of infected erythrocytes in the same manner as seen for other var genes both in vitro and in vivo. Only very few children exhibit seroconversion to VAR3 following a malaria episode requiring hospitalization, supporting the previous conclusion drawn from var3 transcript analysis of parasites collected from children hospitalized with malaria, that VAR3 is not associated with severe anaemia or cerebral malaria syndromes in children.
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Affiliation(s)
- Christian W Wang
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Dominique C Bengtsson
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Pamela A Magistrado
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Sanne S Berger
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Andrea M Marquard
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Michael Alifrangis
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - John P Lusingu
- National Institute for Medical Research (NIMR), Tanga Medical Research Centre, Tanga, Tanzania
| | - Thor G Theander
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
| | - Louise Turner
- Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), 1014, Copenhagen, Denmark
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Quelhas D, Jiménez A, Quintó L, Serra-Casas E, Mayor A, Cisteró P, Puyol L, Wilson DW, Richards JS, Nhampossa T, Macete E, Aide P, Mandomando I, Sanz S, Aponte JJ, Alonso PL, Beeson JG, Menéndez C, Dobaño C. IgG against Plasmodium falciparum variant surface antigens and growth inhibitory antibodies in Mozambican children receiving intermittent preventive treatment with sulfadoxine-pyrimethamine. Immunobiology 2011; 216:793-802. [DOI: 10.1016/j.imbio.2010.12.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 12/17/2010] [Accepted: 12/19/2010] [Indexed: 10/18/2022]
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Spadafora C, Gerena L, Kopydlowski KM. Comparison of the in vitro invasive capabilities of Plasmodium falciparum schizonts isolated by Percoll gradient or using magnetic based separation. Malar J 2011; 10:96. [PMID: 21501476 PMCID: PMC3100259 DOI: 10.1186/1475-2875-10-96] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/18/2011] [Indexed: 11/15/2022] Open
Abstract
Background Percoll gradient centrifugation is often used for synchronization, enrichment, or isolation of a particular stage of Plasmodium falciparum. However, Percoll, a hyperosmotic agent, may have harmful effects on the parasites. Magnetic bead column (MBC) separation has been used as an alternative. This is a report of a head-to-head comparison of the in vitro invasive capabilities of parasites isolated by either of the two methods. Methods The P. falciparum laboratory strain isolate 7G8 was grown in vitro using standard procedures and synchronized using 5% sorbitol. On separate days when the schizont parasitaemia was >1%, the culture was split and half was processed by Percoll gradient centrifugation and the other half by magnetic bead column separation. Both processed parasites were placed back in culture and allowed to invade new uninfected erythrocytes. Results In 10 paired assays, the mean efficiency of invasion of 7G8 parasites treated by Percoll gradient centrifugation was 35.8% that of those treated by magnetic bead column separation (95% CI, p = 0.00067) A paired t test with two tails was used for these comparisons. Conclusions In this comparison, magnetic bead column separation of 7G8 schizonts resulted in higher viability and efficiency of invasion than utilizing Percoll gradient centrifugation.
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Affiliation(s)
- Carmenza Spadafora
- Cellular Injury Department, Division of Military Casualty Research, Walter Reed Army Institute of Research, 503 Robert Grant Ave,, Silver Spring, MD 20902, USA.
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Patarroyo ME, Bermúdez A, Patarroyo MA. Structural and Immunological Principles Leading to Chemically Synthesized, Multiantigenic, Multistage, Minimal Subunit-Based Vaccine Development. Chem Rev 2011; 111:3459-507. [DOI: 10.1021/cr100223m] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manuel Elkin Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad Nacional de Colombia
| | - Adriana Bermúdez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad del Rosario
| | - Manuel Alfonso Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad del Rosario
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Differential drug efflux or accumulation does not explain variation in the chloroquine response of Plasmodium falciparum strains expressing the same isoform of mutant PfCRT. Antimicrob Agents Chemother 2011; 55:2310-8. [PMID: 21343459 DOI: 10.1128/aac.01167-10] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutant forms of the Plasmodium falciparum chloroquine resistance transporter (PfCRT) mediate chloroquine resistance by effluxing the drug from the parasite's digestive vacuole, the acidic organelle in which chloroquine exerts its parasiticidal effect. However, different parasites bearing the same mutant form of PfCRT can vary substantially in their chloroquine susceptibility. Here, we have investigated the biochemical basis for the difference in chloroquine response among transfectant parasite lines having different genetic backgrounds but bearing the same mutant form of PfCRT. Despite showing significant differences in their chloroquine susceptibility, all lines with the mutant PfCRT showed a similar chloroquine-induced H+ leak from the digestive vacuole, indicative of similar rates of PfCRT-mediated chloroquine efflux. Furthermore, all lines showed similarly reduced levels of drug accumulation. Factors other than chloroquine efflux and accumulation therefore influence the susceptibility to this drug in parasites expressing mutant PfCRT. Furthermore, in some but not all strains bearing mutant PfCRT, the 50% inhibitory concentration (IC50) for chloroquine and the degree of resistance compared to that of recombinant control parasites varied with the length of the parasite growth assays. In these parasites, the 50% inhibitory concentration for chloroquine measured in 72- or 96-h assays was significantly lower than that measured in 48-h assays. This highlights the importance of considering the first- and second-cycle activities of chloroquine in future studies of parasite susceptibility to this drug.
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Grimberg BT. Methodology and application of flow cytometry for investigation of human malaria parasites. J Immunol Methods 2011; 367:1-16. [PMID: 21296083 DOI: 10.1016/j.jim.2011.01.015] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 12/29/2010] [Accepted: 01/27/2011] [Indexed: 02/03/2023]
Abstract
Historically, examinations of the inhibition of malaria parasite growth/invasion, whether using drugs or antibodies, have relied on the use of microscopy or radioactive hypoxanthine uptake. These are considered gold standards for measuring the effectiveness of antimalarial treatments, however, these methods have well known shortcomings. With the advent of flow cytometry coupled with the use of fluorescent DNA stains allowed for increased speed, reproducibility, and qualitative estimates of the effectiveness of antibodies and drugs to limit malaria parasite growth which addresses the challenges of traditional techniques. Because materials and machines available to research facilities are so varied, different methods have been developed to investigate malaria parasites by flow cytometry. This review is intended to serve as a reference guide for advanced users and importantly, as a primer for new users, to support expanded use and improvements to malaria flow cytometry, particularly in endemic countries.
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Affiliation(s)
- Brian T Grimberg
- Center for Global Health and Diseases, Case Western Reserve, University, Wolstein Research Building, 4-134 Cleveland, OH 44106-7286, United States.
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