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McLean FE, Azasi Y, Sutherland C, Toboh E, Ansong D, Agbenyega T, Awandare G, Rowe JA. Detection of naturally acquired, strain-transcending antibodies against rosetting Plasmodium falciparum strains in humans. Infect Immun 2024; 92:e0001524. [PMID: 38842304 PMCID: PMC11238554 DOI: 10.1128/iai.00015-24] [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: 01/11/2024] [Accepted: 04/29/2024] [Indexed: 06/07/2024] Open
Abstract
Strain-transcending antibodies against virulence-associated subsets of P. falciparum-infected erythrocyte surface antigens could protect children from severe malaria. However, the evidence supporting the existence of such antibodies is incomplete and inconsistent. One subset of surface antigens associated with severe malaria, rosette-mediating Plasmodium falciparum Erythrocyte Membrane Protein one (PfEMP1) variants, cause infected erythrocytes to bind to uninfected erythrocytes to form clusters of cells (rosettes) that contribute to microvascular obstruction and pathology. Here, we tested plasma from 80 individuals living in malaria-endemic regions for IgG recognition of the surface of four P. falciparum rosetting strains using flow cytometry. Broadly reactive plasma samples were then used in antibody elution experiments in which intact IgG was eluted from the surface of infected erythrocytes and transferred to heterologous rosetting strains to look for strain-transcending antibodies. We found that seroprevalence (percentage of positive plasma samples) against allopatric rosetting strains was high in adults (63%-93%) but lower in children (13%-48%). Strain-transcending antibodies were present in nine out of eleven eluted antibody experiments, with six of these recognizing multiple heterologous rosetting parasite strains. One eluate had rosette-disrupting activity against heterologous strains, suggesting PfEMP1 as the likely target of the strain-transcending antibodies. Naturally acquired strain-transcending antibodies to rosetting P. falciparum strains in humans have not been directly demonstrated previously. Their existence suggests that such antibodies could play a role in clinical protection and raises the possibility that conserved epitopes recognized by strain-transcending antibodies could be targeted therapeutically by monoclonal antibodies or vaccines.
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Affiliation(s)
- Florence E. McLean
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Yvonne Azasi
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Cameron Sutherland
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Daniel Ansong
- Kwame Nkrumah University of Science and Technology, School of Medical Sciences, Kumasi, Ghana
- Departments of Child Health and Medicine, Komfo Anokye Teaching Hospital, Kumasi, Ghana
- Malaria Research Centre, Agogo, Ghana
| | - Tsiri Agbenyega
- Kwame Nkrumah University of Science and Technology, School of Medical Sciences, Kumasi, Ghana
- Departments of Child Health and Medicine, Komfo Anokye Teaching Hospital, Kumasi, Ghana
- Malaria Research Centre, Agogo, Ghana
| | - Gordon Awandare
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
| | - J. Alexandra Rowe
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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2
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Bhide AR, Surve DH, Jindal AB. Nanocarrier based active targeting strategies against erythrocytic stage of malaria. J Control Release 2023; 362:297-308. [PMID: 37625598 DOI: 10.1016/j.jconrel.2023.08.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 08/03/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023]
Abstract
The Global Technical Strategy for Malaria 2016-2030 aims to achieve a 90% reduction in malaria cases, and strategic planning and execution are crucial for accomplishing this target. This review aims to understand the complex interaction between erythrocytic receptors and parasites and to use this knowledge to actively target the erythrocytic stage of malaria. The review provides insight into the malaria life cycle, which involves various receptors such as glycophorin A, B, C, and D (GPA/B/C/D), complement receptor 1, basigin, semaphorin 7a, Band 3/ GPA, Kx, and heparan sulfate proteoglycan for parasite cellular binding and ingress in the erythrocytic and exo-erythrocytic stages. Synthetic peptides mimicking P. falciparum receptor binding ligands, human serum albumin, chondroitin sulfate, synthetic polymers, and lipids have been utilized as ligands and decorated onto nanocarriers for specific targeting to parasite-infected erythrocytes. The need of the hour for treatment and prophylaxis against malaria is a broadened horizon that includes multiple targeting strategies against the entry, proliferation, and transmission stages of the parasite. Platform technologies with established pre-clinical safety and efficacy should be translated into clinical evaluation and formulation scale-up. Future development should be directed towards nanovaccines as proactive tools against malaria infection.
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Affiliation(s)
- Atharva R Bhide
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Jhunjhunu, Rajasthan 333031, India
| | - Dhanashree H Surve
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, United States
| | - Anil B Jindal
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Jhunjhunu, Rajasthan 333031, India.
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3
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Bhattacharjee S, Ghosh D, Saha R, Sarkar R, Kumar S, Khokhar M, Pandey RK. Mechanism of Immune Evasion in Mosquito-Borne Diseases. Pathogens 2023; 12:pathogens12050635. [PMID: 37242305 DOI: 10.3390/pathogens12050635] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/28/2023] Open
Abstract
In recent decades, mosquito-borne illnesses have emerged as a major health burden in many tropical regions. These diseases, such as malaria, dengue fever, chikungunya, yellow fever, Zika virus infection, Rift Valley fever, Japanese encephalitis, and West Nile virus infection, are transmitted through the bite of infected mosquitoes. These pathogens have been shown to interfere with the host's immune system through adaptive and innate immune mechanisms, as well as the human circulatory system. Crucial immune checkpoints such as antigen presentation, T cell activation, differentiation, and proinflammatory response play a vital role in the host cell's response to pathogenic infection. Furthermore, these immune evasions have the potential to stimulate the human immune system, resulting in other associated non-communicable diseases. This review aims to advance our understanding of mosquito-borne diseases and the immune evasion mechanisms by associated pathogens. Moreover, it highlights the adverse outcomes of mosquito-borne disease.
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Affiliation(s)
| | - Debanjan Ghosh
- Department of Biotechnology, Pondicherry University, Puducherry 605014, India
| | - Rounak Saha
- Department of Biochemistry and Molecular Biology, Pondicherry University, Puducherry 605014, India
| | - Rima Sarkar
- DBT Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, India
| | - Saurav Kumar
- DBT Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, India
| | - Manoj Khokhar
- Department of Biochemistry, AIIMS, Jodhpur 342005, India
| | - Rajan Kumar Pandey
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 77 Solna, Sweden
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4
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Quintana MDP, Ch'ng JH. Measuring Rosetting Inhibition in Plasmodium falciparum Parasites Using a Flow Cytometry-Based Assay. Methods Mol Biol 2022; 2470:493-503. [PMID: 35881369 DOI: 10.1007/978-1-0716-2189-9_37] [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
Rosetting is the ability of Plasmodium falciparum-infected erythrocytes (IEs) to bind to host receptors on the surface of uninfected erythrocytes (uE) leading to the formation of a cluster of cells with a central IE surrounded by uE. It is a hallmark event during the pathogenesis of P. falciparum malaria, the most severe species causing malaria, which affects mostly young children in Africa. There are no current treatments effectively targeting and disrupting parasite rosette formation. Here, we detail a high-throughput, flow cytometry based assay that allows testing and identification of potential rosetting-inhibitory compounds that could be used in combination with anti-plasmodial drugs to reduce malaria morbidity and mortality.
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Affiliation(s)
- Maria Del Pilar Quintana
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark.
| | - Jun-Hong Ch'ng
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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5
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Hedberg P, Sirel M, Moll K, Kiwuwa MS, Höglund P, Ribacke U, Wahlgren M. Red blood cell blood group A antigen level affects the ability of heparin and PfEMP1 antibodies to disrupt Plasmodium falciparum rosettes. Malar J 2021; 20:441. [PMID: 34794445 PMCID: PMC8600353 DOI: 10.1186/s12936-021-03975-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 11/07/2021] [Indexed: 11/23/2022] Open
Abstract
Background The histo-blood group ABO system has been associated with adverse outcomes in COVID-19, thromboembolic diseases and Plasmodium falciparum malaria. An integral part of the severe malaria pathogenesis is rosetting, the adherence of parasite infected red blood cells (RBCs) to uninfected RBCs. Rosetting is influenced by the host’s ABO blood group (Bg) and rosettes formed in BgA have previously been shown to be more resilient to disruption by heparin and shield the parasite derived surface antigens from antibodies. However, data on rosetting in weak BgA subgroups is scarce and based on investigations of relatively few donors. Methods An improved high-throughput flow cytometric assay was employed to investigate rosetting characteristics in an extensive panel of RBC donor samples of all four major ABO Bgs, as well as low BgA expressing samples. Results All non-O Bgs shield the parasite surface antigens from strain-specific antibodies towards P. falciparum erythrocyte membrane protein 1 (PfEMP1). A positive correlation between A-antigen levels on RBCs and rosette tightness was observed, protecting the rosettes from heparin- and antibody-mediated disruption. Conclusions These results provide new insights into how the ABO Bg system affects the disease outcome and cautions against interpreting the results from the heterogeneous BgA phenotype as a single group in epidemiological and experimental studies. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03975-w.
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Affiliation(s)
- Pontus Hedberg
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, 171 65, Stockholm, Sweden.,Department of Infectious Diseases, Karolinska University Hospital, 171 76, Stockholm, Sweden
| | - Madle Sirel
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, 171 65, Stockholm, Sweden
| | - Kirsten Moll
- Department of Medicine, Huddinge, Karolinska University Hospital, 141 86, Stockholm, Sweden
| | - Mpungu Steven Kiwuwa
- Department of Child Health and Development Centre, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Petter Höglund
- Department of Medicine, Huddinge, Karolinska University Hospital, 141 86, Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, 171 65, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, 171 65, Stockholm, Sweden.
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6
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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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7
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Hoo R, Bruske E, Dimonte S, Zhu L, Mordmüller B, Sim BKL, Kremsner PG, Hoffman SL, Bozdech Z, Frank M, Preiser PR. Transcriptome profiling reveals functional variation in Plasmodium falciparum parasites from controlled human malaria infection studies. EBioMedicine 2019; 48:442-452. [PMID: 31521613 PMCID: PMC6838377 DOI: 10.1016/j.ebiom.2019.09.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/29/2019] [Accepted: 09/01/2019] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The transcriptome of Plasmodium falciparum clinical isolates varies according to strain, mosquito bites, disease severity and clinical history. Therefore, it remains a challenge to directly interpret the parasite's transcriptomic information into a more general biological signature in a natural human malaria infection. These confounding variations can be potentially overcome with parasites derived from controlled-human malaria infection (CHMI) studies. METHODS We performed CHMI studies in healthy and immunologically naïve volunteers receiving the same P. falciparum strain ((Sanaria® PfSPZ Challenge (NF54)), but with different sporozoite dosage and route of infection. Parasites isolated from these volunteers at the day of patency were subjected to in vitro culture for several generations and synchronized ring-stage parasites were subjected to transcriptome profiling. FINDINGS We observed clear deviations between CHMI-derived parasites from volunteer groups receiving different PfSPZ dose and route. CHMI-derived parasites and the pre-mosquito strain used for PfSPZ generation showed significant transcriptional variability for gene clusters associated with malaria pathogenesis, immune evasion and transmission. These transcriptional variation signature clusters were also observed in the transcriptome of P. falciparum isolates from acute clinical infections. INTERPRETATION Our work identifies a previously unrecognized transcriptional pattern in malaria infections in a non-immune background. Significant transcriptome heterogeneity exits between parasites derived from human infections and the pre-mosquito strain, implying that the malaria parasites undergo a change in functional state to adapt to its host environment. Our work also highlights the potential use of transcriptomics data from CHMI study advance our understanding of malaria parasite adaptation and transmission in humans. FUND: This work is supported by German Israeli Foundation, German ministry for education and research, MOE Tier 1 from the Singapore Ministry of Education Academic Research Fund, Singapore Ministry of Health's National Medical Research Council, National Institute of Allergy and Infectious Diseases, National Institutes of Health, USA and the German Centre for Infection Research (Deutsches Zentrum für Infektionsforschung-DZIF).
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Affiliation(s)
- Regina Hoo
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Ellen Bruske
- Institute of Tropical Medicine, Wilhelmstr. 27, University of Tübingen, 72074 Tübingen, Germany
| | - Sandra Dimonte
- Institute of Tropical Medicine, Wilhelmstr. 27, University of Tübingen, 72074 Tübingen, Germany
| | - Lei Zhu
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, Wilhelmstr. 27, University of Tübingen, 72074 Tübingen, Germany; German Center for Infection Research, partner site Tübingen, Germany
| | - B Kim Lee Sim
- Sanaria Inc, 9800 Medical Center Dr A209, Rockville, MD 20850, USA
| | - Peter G Kremsner
- Institute of Tropical Medicine, Wilhelmstr. 27, University of Tübingen, 72074 Tübingen, Germany; Centre de Recherches Médicales de Lambaréné, BP 242 Lambaréné, Gabon
| | | | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Matthias Frank
- Institute of Tropical Medicine, Wilhelmstr. 27, University of Tübingen, 72074 Tübingen, Germany.
| | - Peter R Preiser
- School of Biological Sciences, Nanyang Technological University, Singapore.
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8
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Rosetting revisited: a critical look at the evidence for host erythrocyte receptors in Plasmodium falciparum rosetting. Parasitology 2019; 147:1-11. [PMID: 31455446 PMCID: PMC7050047 DOI: 10.1017/s0031182019001288] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Malaria remains a major cause of mortality in African children, with no adjunctive treatments currently available to ameliorate the severe clinical forms of the disease. Rosetting, the adhesion of infected erythrocytes (IEs) to uninfected erythrocytes, is a parasite phenotype strongly associated with severe malaria, and hence is a potential therapeutic target. However, the molecular mechanisms of rosetting are complex and involve multiple distinct receptor–ligand interactions, with some similarities to the diverse pathways involved in P. falciparum erythrocyte invasion. This review summarizes the current understanding of the molecular interactions that lead to rosette formation, with a particular focus on host uninfected erythrocyte receptors including the A and B blood group trisaccharides, complement receptor one, heparan sulphate, glycophorin A and glycophorin C. There is strong evidence supporting blood group A trisaccharides as rosetting receptors, but evidence for other molecules is incomplete and requires further study. It is likely that additional host erythrocyte rosetting receptors remain to be discovered. A rosette-disrupting low anti-coagulant heparin derivative is being investigated as an adjunctive therapy for severe malaria, and further research into the receptor–ligand interactions underlying rosetting may reveal additional therapeutic approaches to reduce the unacceptably high mortality rate of severe malaria.
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9
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Derkach A, Otim I, Pfeiffer RM, Onabajo OO, Legason ID, Nabalende H, Ogwang MD, Kerchan P, Talisuna AO, Ayers LW, Reynolds SJ, Nkrumah F, Neequaye J, Bhatia K, Theander TG, Prokunina-Olsson L, Turner L, Goedert JJ, Lavstsen T, Mbulaiteye SM. Associations between IgG reactivity to Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) antigens and Burkitt lymphoma in Ghana and Uganda case-control studies. EBioMedicine 2018; 39:358-368. [PMID: 30579868 PMCID: PMC6355394 DOI: 10.1016/j.ebiom.2018.12.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 01/26/2023] Open
Abstract
Background Endemic Burkitt lymphoma (eBL) is an aggressive childhood B-cell lymphoma linked to Plasmodium falciparum (Pf) malaria in sub-Saharan Africa. We investigated antibody reactivity to several human receptor-binding domains of the Pf erythrocyte membrane protein 1 (PfEMP1) that play a key role in malaria pathogenesis and are targets of acquired immunity to malaria. Methods Serum/plasma IgG antibody reactivity was measured to 22 Pf antigens, including 18 to PfEMP1 CIDR domains between cases and controls from two populations (149 eBL cases and 150 controls from Ghana and 194 eBL cases and 600 controls from Uganda). Adjusted odds ratios (aORs) for case-control associations were estimated by logistic regression. Findings There was stronger reactivity to the severe malaria associated CIDRα1 domains than other CIDR domains both in cases and controls. eBL cases reacted to fewer antigens than controls (Ghana: p = 0·001; Uganda: p = 0·03), with statistically significant lower ORs associated with reactivity to 13+ antigens in Ghana (aOR 0·39, 95% CI 0·24–0·63; pheterogeneity = 0·00011) and Uganda (aOR 0·60, 95% CI 0.41–0·88; pheterogeneity = 0·008). eBL was inversely associated with reactivity, coded as quartiles, to group A variant CIDRδ1 (ptrend = 0·035) in Ghana and group B CD36-binding variants CIDRα2·2 (ptrend = 0·006) and CIDRα2·4 (ptrend = 0·033) in Uganda, and positively associated with reactivity to SERA5 in Ghana (ptrend = 0·017) and Uganda (ptrend = 0·007) and group A CIDRα1·5 variant in Uganda only (ptrend = 0·034). Interpretation eBL cases reacted to fewer antigens than controls using samples from two populations, Ghana and Uganda. Attenuated humoral immunity to Pf EMP1 may contribute to susceptibility to low-grade malaria and eBL risk. Funding Intramural Research Program, National Cancer Institute and National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services.
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Affiliation(s)
- Andriy Derkach
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Isaac Otim
- EMBLEM Study, African Field Epidemiology Network, Kampala, Uganda
| | - Ruth M Pfeiffer
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Olusegun O Onabajo
- Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ismail D Legason
- EMBLEM Study, African Field Epidemiology Network, Kampala, Uganda
| | | | | | | | - Ambrose O Talisuna
- World Health Organization, Regional Office for Africa, Brazzaville, Congo
| | - Leona W Ayers
- Department of Pathology, The Ohio State University, Columbus, OH, USA
| | - Steven J Reynolds
- Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | | | - Janet Neequaye
- Department of Child Health, Korle Bu University Teaching Hospital in Accra, Ghana
| | - Kishor Bhatia
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Thor G Theander
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, University of Copenhagen and Department of Infectious Diseases, Rigs Hospitalet, Copenhagen, Denmark
| | - Ludmila Prokunina-Olsson
- Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Louise Turner
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, University of Copenhagen and Department of Infectious Diseases, Rigs Hospitalet, Copenhagen, Denmark
| | - James J Goedert
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, University of Copenhagen and Department of Infectious Diseases, Rigs Hospitalet, Copenhagen, Denmark
| | - Sam M Mbulaiteye
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
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10
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Yam XY, Preiser PR. Host immune evasion strategies of malaria blood stage parasite. MOLECULAR BIOSYSTEMS 2018; 13:2498-2508. [PMID: 29091093 DOI: 10.1039/c7mb00502d] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Host immune evasion is a key strategy for the continual survival of many microbial pathogens including Apicomplexan protozoan: Plasmodium spp., the causative agent of Malaria. The malaria parasite has evolved a variety of mechanisms to evade the host immune responses within its two hosts: the female Anopheles mosquito vector and vertebrate host. In this review, we will focus on the molecular mechanisms of the immune evasion strategies used by the Plasmodium parasite at the blood stage which is responsible for the clinical manifestations of human malaria. We also aim to provide some insights on the potential targets for malaria interventions through the recent advancement in understanding the molecular biology of the parasite.
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Affiliation(s)
- Xue Yan Yam
- School of Biological Sciences, Nanyang Technological University, 637551, Singapore.
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11
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Quintana MDP, Ch'ng JH, Moll K, Zandian A, Nilsson P, Idris ZM, Saiwaew S, Qundos U, Wahlgren M. Antibodies in children with malaria to PfEMP1, RIFIN and SURFIN expressed at the Plasmodium falciparum parasitized red blood cell surface. Sci Rep 2018; 8:3262. [PMID: 29459776 PMCID: PMC5818650 DOI: 10.1038/s41598-018-21026-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 01/12/2018] [Indexed: 01/21/2023] Open
Abstract
Naturally acquired antibodies to proteins expressed on the Plasmodium falciparum parasitized red blood cell (pRBC) surface steer the course of a malaria infection by reducing sequestration and stimulating phagocytosis of pRBC. Here we have studied a selection of proteins representing three different parasite gene families employing a well-characterized parasite with a severe malaria phenotype (FCR3S1.2). The presence of naturally acquired antibodies, impact on rosetting rate, surface reactivity and opsonization for phagocytosis in relation to different blood groups of the ABO system were assessed in a set of sera from children with mild or complicated malaria from an endemic area. We show that the naturally acquired immune responses, developed during malaria natural infection, have limited access to the pRBCs inside a blood group A rosette. The data also indicate that SURFIN4.2 may have a function at the pRBC surface, particularly during rosette formation, this role however needs to be further validated. Our results also indicate epitopes differentially recognized by rosette-disrupting antibodies on a peptide array. Antibodies towards parasite-derived proteins such as PfEMP1, RIFIN and SURFIN in combination with host factors, essentially the ABO blood group of a malaria patient, are suggested to determine the outcome of a malaria infection.
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Affiliation(s)
- Maria Del Pilar Quintana
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
| | - Jun-Hong Ch'ng
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.,Department of Microbiology and Immunology, National University of Singapore, Singapore, Singapore
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Arash Zandian
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, KTH-Royal Institutet of Technology, Stockholm, Sweden
| | - Peter Nilsson
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, KTH-Royal Institutet of Technology, Stockholm, Sweden
| | - Zulkarnain Md Idris
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.,Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan, Malaysia Medical Centre, Kuala Lumpur, Malaysia
| | - Somporn Saiwaew
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Ulrika Qundos
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, KTH-Royal Institutet of Technology, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
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12
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Wahlgren M, Goel S, Akhouri RR. Variant surface antigens of Plasmodium falciparum and their roles in severe malaria. Nat Rev Microbiol 2017; 15:479-491. [DOI: 10.1038/nrmicro.2017.47] [Citation(s) in RCA: 142] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Three Is a Crowd – New Insights into Rosetting in Plasmodium falciparum. Trends Parasitol 2017; 33:309-320. [DOI: 10.1016/j.pt.2016.12.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/17/2016] [Accepted: 12/19/2016] [Indexed: 12/29/2022]
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14
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Saiwaew S, Sritabal J, Piaraksa N, Keayarsa S, Ruengweerayut R, Utaisin C, Sila P, Niramis R, Udomsangpetch R, Charunwatthana P, Pongponratn E, Pukrittayakamee S, Leitgeb AM, Wahlgren M, Lee SJ, Day NPJ, White NJ, Dondorp AM, Chotivanich K. Effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum infected erythrocytes. PLoS One 2017; 12:e0172718. [PMID: 28249043 PMCID: PMC5332063 DOI: 10.1371/journal.pone.0172718] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 02/08/2017] [Indexed: 12/04/2022] Open
Abstract
In severe falciparum malaria cytoadherence of parasitised red blood cells (PRBCs) to vascular endothelium (causing sequestration) and to uninfected red cells (causing rosette formation) contribute to microcirculatory flow obstruction in vital organs. Heparin can reverse the underlying ligand-receptor interactions, but may increase the bleeding risks. As a heparin-derived polysaccharide, sevuparin has been designed to retain anti-adhesive properties, while the antithrombin-binding domains have been eliminated, substantially diminishing its anticoagulant activity. Sevuparin has been evaluated recently in patients with uncomplicated falciparum malaria, and is currently investigated in a clinical trial for sickle cell disease. The effects of sevuparin on rosette formation and cytoadherence of Plasmodium falciparum isolates from Thailand were investigated. Trophozoite stages of P. falciparum-infected RBCs (Pf-iRBCs) were cultured from 49 patients with malaria. Pf-iRBCs were treated with sevuparin at 37°C and assessed in rosetting and in cytoadhesion assays with human dermal microvascular endothelial cells (HDMECs) under static and flow conditions. The proportion of Pf-iRBCs forming rosettes ranged from 6.5% to 26.0% (median = 12.2%). Rosetting was dose dependently disrupted by sevuparin (50% disruption by 250 μg/mL). Overall 57% of P. falciparum isolates bound to HDMECs under static conditions; median (interquartile range) Pf-iRBC binding was 8.5 (3.0–38.0) Pf-iRBCs/1000 HDMECs. Sevuparin in concentrations ≥ 100 μg/mL inhibited cytoadherence. Sevuparin disrupts P. falciparum rosette formation in a dose dependent manner and inhibits cytoadherence to endothelial cells. The data support assessment of sevuparin as an adjunctive treatment to the standard therapy in severe falciparum malaria.
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Affiliation(s)
- Somporn Saiwaew
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Juntima Sritabal
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nattaporn Piaraksa
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Srisuda Keayarsa
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | | | - Patima Sila
- Mae Ramat Hospital, Mae Ramat, Tak, Thailand
| | - Rangsan Niramis
- Queen Sirikit National Institute of Child Health, Bangkok, Thailand
| | - Rachanee Udomsangpetch
- Center for Research and Innovation, Faculty of Medical Technology, Mahidol University, Nakhon Pathom, Thailand
| | - Prakaykaew Charunwatthana
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Emsri Pongponratn
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sasithon Pukrittayakamee
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Sue J. Lee
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Arjen M. Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Kesinee Chotivanich
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- * E-mail:
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15
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Ch'ng JH, Sirel M, Zandian A, Del Pilar Quintana M, Chun Leung Chan S, Moll K, Tellgren-Roth A, Nilsson I, Nilsson P, Qundos U, Wahlgren M. Epitopes of anti-RIFIN antibodies and characterization of rif-expressing Plasmodium falciparum parasites by RNA sequencing. Sci Rep 2017; 7:43190. [PMID: 28233866 PMCID: PMC5324397 DOI: 10.1038/srep43190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/20/2017] [Indexed: 12/28/2022] Open
Abstract
Variable surface antigens of Plasmodium falciparum have been a major research focus since they facilitate parasite sequestration and give rise to deadly malaria complications. Coupled with its potential use as a vaccine candidate, the recent suggestion that the repetitive interspersed families of polypeptides (RIFINs) mediate blood group A rosetting and influence blood group distribution has raised the research profile of these adhesins. Nevertheless, detailed investigations into the functions of this highly diverse multigene family remain hampered by the limited number of validated reagents. In this study, we assess the specificities of three promising polyclonal anti-RIFIN antibodies that were IgG-purified from sera of immunized animals. Their epitope regions were mapped using a 175,000-peptide microarray holding overlapping peptides of the P. falciparum variable surface antigens. Through immunoblotting and immunofluorescence imaging, we show that different antibodies give varying results in different applications/assays. Finally, we authenticate the antibody-based detection of RIFINs in two previously uncharacterized non-rosetting parasite lines by identifying the dominant rif transcripts using RNA sequencing.
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Affiliation(s)
- Jun-Hong Ch'ng
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.,Department of Microbiology and Immunology, National University of Singapore, Singapore
| | - Madle Sirel
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Arash Zandian
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Maria Del Pilar Quintana
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Sherwin Chun Leung Chan
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Asa Tellgren-Roth
- Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - IngMarie Nilsson
- Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Peter Nilsson
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Ulrika Qundos
- Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
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16
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Moles E, Moll K, Ch'ng JH, Parini P, Wahlgren M, Fernàndez-Busquets X. Development of drug-loaded immunoliposomes for the selective targeting and elimination of rosetting Plasmodium falciparum-infected red blood cells. J Control Release 2016; 241:57-67. [PMID: 27620073 DOI: 10.1016/j.jconrel.2016.09.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 09/06/2016] [Accepted: 09/07/2016] [Indexed: 11/20/2022]
Abstract
Parasite proteins exported to the surface of Plasmodium falciparum-parasitized red blood cells (pRBCs) have a major role in severe malaria clinical manifestation, where pRBC cytoadhesion and rosetting processes have been strongly linked with microvascular sequestration while avoiding both spleen filtration and immune surveillance. The parasite-derived and pRBC surface-exposed PfEMP1 protein has been identified as one of the responsible elements for rosetting and, therefore, considered as a promising vaccine candidate for the generation of rosette-disrupting antibodies against severe malaria. However, the potential role of anti-rosetting antibodies as targeting molecules for the functionalization of antimalarial drug-loaded nanovectors has never been studied. Our manuscript presents a proof-of-concept study where the activity of an immunoliposomal vehicle with a dual performance capable of specifically recognizing and disrupting rosettes while simultaneously eliminating those pRBCs forming them has been assayed in vitro. A polyclonal antibody against the NTS-DBL1α N-terminal domain of a rosetting PfEMP1 variant has been selected as targeting molecule and lumefantrine as the antimalarial payload. After 30min incubation with 2μM encapsulated drug, a 70% growth inhibition for all parasitic forms in culture (IC50: 414nM) and a reduction in ca. 60% of those pRBCs with a rosetting phenotype (IC50: 747nM) were achieved. This immunoliposomal approach represents an innovative combination therapy for the improvement of severe malaria therapeutics having a broader spectrum of activity than either anti-rosetting antibodies or free drugs on their own.
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Affiliation(s)
- Ernest Moles
- Nanomalaria Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 10-12, ES-08028 Barcelona, Spain; Barcelona Institute for Global Health (ISGlobal), Barcelona Center for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Rosselló 149-153, ES-08036 Barcelona, Spain; Nanoscience and Nanotechnology Institute (IN2UB), University of Barcelona, Martí i Franquès 1, ES-08028 Barcelona, Spain.
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Jun-Hong Ch'ng
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden; Department of Microbiology, National University of Singapore, Singapore
| | - Paolo Parini
- Department of Laboratory Medicine (LABMED), H5, Division of Clinical Chemistry, Karolinska Institutet, Huddinge, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Xavier Fernàndez-Busquets
- Nanomalaria Group, Institute for Bioengineering of Catalonia (IBEC), Baldiri Reixac 10-12, ES-08028 Barcelona, Spain; Barcelona Institute for Global Health (ISGlobal), Barcelona Center for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Rosselló 149-153, ES-08036 Barcelona, Spain; Nanoscience and Nanotechnology Institute (IN2UB), University of Barcelona, Martí i Franquès 1, ES-08028 Barcelona, Spain.
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17
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Quintana MDP, Angeletti D, Moll K, Chen Q, Wahlgren M. Phagocytosis-inducing antibodies to Plasmodium falciparum upon immunization with a recombinant PfEMP1 NTS-DBL1α domain. Malar J 2016; 15:416. [PMID: 27531359 PMCID: PMC4987995 DOI: 10.1186/s12936-016-1459-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 07/29/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Individuals living in endemic areas gradually acquire natural immunity to clinical malaria, largely dependent on antibodies against parasite antigens. There are many studies indicating that the variant antigen PfEMP1 at the surface of the parasitized red blood cell (pRBC) is one of the major targets of the immune response. It is believed that antibodies against PfEMP1 confer protection by blocking sequestration (rosetting and cytoadherence), inducing antibody-dependent cellular-inhibitory effect and opsonizing pRBCs for phagocytosis. METHODS A recombinant NTS-DBL1α domain from a rosette-mediating PfEMP1 was expressed in Escherichia coli. The resulting protein was purified and used for immunization to generate polyclonal (goat) and monoclonal (mouse) antibodies. The antibodies' ability to opsonize and induce phagocytosis in vitro was tested and contrasted with the presence of opsonizing antibodies naturally acquired during Plasmodium falciparum infection. RESULTS All antibodies recognized the recombinant antigen and the surface of live pRBCs, however, their capacity to opsonize the pRBCs for phagocytosis varied. The monoclonal antibodies isotyped as IgG2b did not induce phagocytosis, while those isotyped as IgG2a were in general very effective, inducing phagocytosis with similar levels as those naturally acquired during P. falciparum infection. These monoclonal antibodies displayed different patterns, some of them showing a concentration-dependent activity while others showed a prozone-like effect. The goat polyclonal antibodies were not able to induce phagocytosis. CONCLUSION Immunization with an NTS-DBL1-α domain of PfEMP1 generates antibodies that not only have a biological role in rosette disruption but also effectively induce opsonization for phagocytosis of pRBCs with similar activity to naturally acquired antibodies from immune individuals living in a malaria endemic area. Some of the antibodies with high opsonizing activity were not able to disrupt rosettes, indicating that epitopes of the NTS-DBL1-α other than those involved in rosetting are exposed on the pRBC surface and are able to induce functional antibodies. The ability to induce phagocytosis largely depended on the antibody isotype and on the ability to recognize the surface of the pRBC regardless of the rosette-disrupting capacity.
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Affiliation(s)
- Maria Del Pilar Quintana
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.,Escuela de Medicina y Ciencias de la Salud, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Bogotá, Colombia
| | - Davide Angeletti
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Qijun Chen
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.,Key Laboratory of Zoonosis, Jilin University, Changchun, People's Republic of China.,Institute of Pathogen Biology, Chinese Academy of Medical Sciences, Beijing, People's Republic of China
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
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18
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Guillotte M, Nato F, Juillerat A, Hessel A, Marchand F, Lewit-Bentley A, Bentley GA, Vigan-Womas I, Mercereau-Puijalon O. Functional analysis of monoclonal antibodies against the Plasmodium falciparum PfEMP1-VarO adhesin. Malar J 2016; 15:28. [PMID: 26772184 PMCID: PMC4715314 DOI: 10.1186/s12936-015-1016-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/24/2015] [Indexed: 01/30/2023] Open
Abstract
Background Rosetting, namely the capacity of the Plasmodium falciparum-infected red blood cells to bind uninfected RBCs, is commonly observed in African children with severe malaria. Rosetting results from specific interactions between a subset of variant P. falciparum erythrocyte membrane protein 1 (PfEMP1) adhesins encoded by var genes, serum components and RBC receptors. Rosette formation is a redundant phenotype, as there exists more than one var gene encoding a rosette-mediating PfEMP1 in each genome and hence a diverse array of underlying interactions. Moreover, field diversity creates a large panel of rosetting-associated serotypes and studies with human immune sera indicate that surface-reacting antibodies are essentially variant-specific. To gain better insight into the interactions involved in rosetting and map surface epitopes, a panel of monoclonal antibodies (mAbs) was investigated. Methods Monoclonal antibodies were isolated from mice immunized with PfEMP1-VarO recombinant domains. They were characterized using ELISA and reactivity with the native PfEMP1-VarO adhesin on immunoblots of reduced and unreduced extracts, as well as SDS-extracts of Palo Alto 89F5 VarO schizonts. Functionality was assessed using inhibition of Palo Alto 89F5 VarO rosette formation and disruption of Palo Alto 89F5 VarO rosettes. Competition ELISAs were performed with biotinylated antibodies against DBL1 to identify reactivity groups. Specificity of mAbs reacting with the DBL1 adhesion domain was explored using recombinant proteins carrying mutations abolishing RBC binding or binding to heparin, a potent inhibitor of rosette formation. Results Domain-specific, surface-reacting mAbs were obtained for four individual domains (DBL1, CIDR1, DBL2, DBL4). Monoclonal antibodies reacting with DBL1 potently inhibited the formation of rosettes and disrupted Palo Alto 89F5 VarO rosettes. Most surface-reactive mAbs and all mAbs interfering with rosetting reacted on parasite immunoblots with disulfide bond-dependent PfEMP1 epitopes. Based on competition ELISA and binding to mutant DBL1 domains, two distinct binding sites for rosette-disrupting mAbs were identified in close proximity to the RBC-binding site. Conclusions Rosette-inhibitory antibodies bind to conformation-dependent epitopes located close to the RBC-binding site and distant from the heparin-binding site. These results provide novel clues for a rational intervention strategy that targets rosetting. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-1016-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Micheline Guillotte
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, 25-28 rue du Dr ROUX, 75015, Paris, France. .,URA CNRS 2581, 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Farida Nato
- Institut Pasteur, Plate-forme de Production de Protéines recombinantes et d'Anticorps (PF5), 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Alexandre Juillerat
- Institut Pasteur, Unité d'Immunologie Structurale, 25-28 rue du Dr ROUX, 75015, Paris, France. .,CNRS URA 2185, 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Audrey Hessel
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, 25-28 rue du Dr ROUX, 75015, Paris, France. .,Institut Pasteur, Unité d'Immunologie Structurale, 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Françoise Marchand
- Institut Pasteur, Plate-forme de Production de Protéines recombinantes et d'Anticorps (PF5), 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Anita Lewit-Bentley
- Institut Pasteur, Unité d'Immunologie Structurale, 25-28 rue du Dr ROUX, 75015, Paris, France. .,CNRS URA 2185, 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Graham A Bentley
- Institut Pasteur, Unité d'Immunologie Structurale, 25-28 rue du Dr ROUX, 75015, Paris, France. .,CNRS URA 2185, 25-28 rue du Dr ROUX, 75015, Paris, France.
| | - Inès Vigan-Womas
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, 25-28 rue du Dr ROUX, 75015, Paris, France. .,URA CNRS 2581, 25-28 rue du Dr ROUX, 75015, Paris, France. .,Institut Pasteur de Madagascar, Unité d'Immunologie des Maladies Infectieuses, BP 1274, Antananarivo 101, Madagascar.
| | - Odile Mercereau-Puijalon
- Institut Pasteur, Unité d'Immunologie Moléculaire des Parasites, 25-28 rue du Dr ROUX, 75015, Paris, France. .,URA CNRS 2581, 25-28 rue du Dr ROUX, 75015, Paris, France.
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19
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Architecture of Human IgM in Complex with P. falciparum Erythrocyte Membrane Protein 1. Cell Rep 2016; 14:723-736. [PMID: 26776517 DOI: 10.1016/j.celrep.2015.12.067] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 09/30/2015] [Accepted: 12/11/2015] [Indexed: 11/23/2022] Open
Abstract
Plasmodium falciparum virulence is associated with sequestration of infected erythrocytes. Microvascular binding mediated by PfEMP1 in complex with non-immune immunoglobulin M (IgM) is common among parasites that cause both severe childhood malaria and pregnancy-associated malaria. Here, we present cryo-molecular electron tomography structures of human IgM, PfEMP1 and their complex. Three-dimensional reconstructions of IgM reveal that it has a dome-like core, randomly oriented Fab2s units, and the overall shape of a turtle. PfEMP1 is a C- shaped molecule with a flexible N terminus followed by an arc-shaped backbone and a bulky C terminus that interacts with IgM. Our data demonstrate that the PfEMP1 binding pockets on IgM overlap with those of C1q, and the bulkiness of PfEMP1 limits the capacity of IgM to interact with PfEMP1. We suggest that P. falciparum exploits IgM to cluster PfEMP1 into an organized matrix to augment its affinity to host cell receptors.
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20
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Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 antigens that are inserted onto the surface of P. falciparum infected erythrocytes play a key role both in the pathology of severe malaria and as targets of naturally acquired immunity. They might be considered unlikely vaccine targets because they are extremely diverse. However, several lines of evidence suggest that underneath this molecular diversity there are a restricted set of epitopes which may act as effective targets for a vaccine against severe malaria. Here we review some of the recent developments in this area of research, focusing on work that has assessed the potential of these molecules as possible vaccine targets.
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21
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Moll K, Palmkvist M, Ch'ng J, Kiwuwa MS, Wahlgren M. Evasion of Immunity to Plasmodium falciparum: Rosettes of Blood Group A Impair Recognition of PfEMP1. PLoS One 2015; 10:e0145120. [PMID: 26714011 PMCID: PMC4694710 DOI: 10.1371/journal.pone.0145120] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 11/28/2015] [Indexed: 11/18/2022] Open
Abstract
The ABO blood group antigens are expressed on erythrocytes but also on endothelial cells, platelets and serum proteins. Notably, the ABO blood group of a malaria patient determines the development of the disease given that blood group O reduces the probability to succumb in severe malaria, compared to individuals of groups A, B or AB. P. falciparum rosetting and sequestration are mediated by PfEMP1, RIFIN and STEVOR, expressed at the surface of the parasitized red blood cell (pRBC). Antibodies to these antigens consequently modify the course of a malaria infection by preventing sequestration and promoting phagocytosis of pRBC. Here we have studied rosetting P. falciparum and present evidence of an immune evasion mechanism not previously recognized. We find the accessibility of antibodies to PfEMP1 at the surface of the pRBC to be reduced when P. falciparum forms rosettes in blood group A RBC, as compared to group O RBC. The pRBC surrounds itself with tightly bound normal RBC that makes PfEMP1 inaccessible to antibodies and clearance by the immune system. Accordingly, pRBC of in vitro cloned P. falciparum devoid of ABO blood group dependent rosetting were equally well detected by anti-PfEMP1 antibodies, independent of the blood group utilized for their propagation. The pathogenic mechanisms underlying the severe forms of malaria may in patients of blood group A depend on the ability of the parasite to mask PfEMP1 from antibody recognition, in so doing evading immune clearance.
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Affiliation(s)
- Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
- * E-mail: (KM); (MW)
| | - Mia Palmkvist
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Junhong Ch'ng
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
| | - Mpungu Steven Kiwuwa
- Department of Pediatrics, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
- Department of Biochemistry, School of Biomedical Sciences, Makerere University College of Health Sciences, Kampala, Uganda
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, Nobels väg 16, SE-171 77 Stockholm, Sweden
- * E-mail: (KM); (MW)
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22
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Agrawal MR, Ozarkar AD, Gupta S, Deobagkar DN, Deobagkar DD. Comparative study of Plasmodium falciparum erythrocyte membrane protein 1-DBLα domain variants with respect to antigenic variations and docking interaction analysis with glycosaminoglycans. MOLECULAR BIOSYSTEMS 2015; 10:2466-79. [PMID: 24995459 DOI: 10.1039/c4mb00274a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The variant surface antigen PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1) encoded by the polymorphic multi-copy var gene family plays an important role in parasite biology and the host-parasite interactions. Sequestration and antigenic variation is an essential component in the survival and pathogenesis of Plasmodium falciparum and contributes to chronic infection. The DBLα domain of PfEMP1 is a potential target for immuno-epidemiological studies and has been visualized as a vaccine candidate against severe malaria. Specific host receptors like heparin, heparan sulphate, blood group A and complement receptor 1 have been reported to bind the DBLα domain. Although heparin has been experimentally shown to disrupt the parasite-host interaction and effectively disrupt rosetting, the binding sites for the DBLα domain and the mechanism behind heparin-mediated rosette inhibition have not been elucidated. In this study, 3D structures and epitopes of the DBLα domain in 3D7 and in two Indian isolates have been predicted and compared. We have carried out docking studies on DBLα domains with human GAG receptors (heparin and heparan sulphate) to predict the strength of association between the protein-ligand interactions. The DBLα domain structures showed extensive diversity and polymorphism in their binding sites. The docking results indicate that heparin binds more effectively with high affinity as compared to heparan sulphate with some common interacting residues. These common residues can play an important role in rosetting and will aid in the designing of inhibitors specific to the interactions between DBLα and heparin or heparan sulphate would be important in malaria treatment. Thus it may lead to the development of novel interference strategies to block red blood cell invasion and provide protection against malaria.
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Affiliation(s)
- Megha R Agrawal
- Bioinformatics Centre & Department of Zoology, Center of Advanced Studies, University of Pune, Pune 411007, India.
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Abstract
Members of the clonally variant Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediate adhesion of infected erythrocytes (IEs) to vascular receptors. PfEMP1 expression is normally confined to nanoscale knob protrusions on the IE surface membrane. To investigate the relationship between the densities of these IE surface knobs and the PfEMP1 variant expressed, we used specific antibody panning to generate three sublines of the P. falciparum clone IT4, which expresses the PfEMP1 variants IT4VAR04, IT4VAR32b, and IT4VAR60. The knob density in each subline was then determined by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and compared to PfEMP1 and knob-associated histidine-rich protein (KAHRP) expression. Selection for uniform expression of IT4VAR04 produced little change in knob density, compared to unselected IEs. In contrast, selection for IT4VAR32b expression increased knob density approximately 3-fold, whereas IEs selected for IT4VAR60 expression were essentially knobless. When IT4VAR60+ IEs were subsequently selected to express IT4VAR04 or IT4VAR32b, they again displayed low and high knob densities, respectively. All sublines expressed KAHRP regardless of the PfEMP1 expressed. Our study documents for the first time that knob density is related to the PfEMP1 variant expressed. This may reflect topological requirements to ensure optimal adhesive properties of the IEs. Infections with Plasmodium falciparum malaria parasites are still responsible for many deaths, especially among children and pregnant women. New interventions are needed to reduce severe illness and deaths caused by this malaria parasite. Thus, a better understanding of the mechanisms behind the pathogenesis is essential. A main reason why Plasmodium falciparum malaria is more severe than disease caused by other malaria species is its ability to express variant antigens on the infected erythrocyte surface. These antigens are presented on membrane protrusions known as knobs. This study set out to investigate the interplay between different variant antigens on the surface of P. falciparum-infected erythrocytes and the density of the knobs on which the antigens are expressed. Such a direct analysis of this relationship has not been reported before but adds to the important understanding of the complexity of malaria antigen presentation.
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Niang M, Bei AK, Madnani KG, Pelly S, Dankwa S, Kanjee U, Gunalan K, Amaladoss A, Yeo KP, Bob NS, Malleret B, Duraisingh MT, Preiser PR. STEVOR is a Plasmodium falciparum erythrocyte binding protein that mediates merozoite invasion and rosetting. Cell Host Microbe 2015; 16:81-93. [PMID: 25011110 DOI: 10.1016/j.chom.2014.06.004] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2012] [Revised: 05/06/2014] [Accepted: 06/03/2014] [Indexed: 10/25/2022]
Abstract
Variant surface antigens play an important role in Plasmodium falciparum malaria pathogenesis and in immune evasion by the parasite. Although most work to date has focused on P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1), two other multigene families encoding STEVOR and RIFIN are expressed in invasive merozoites and on the infected erythrocyte surface. However, their role during parasite infection remains to be clarified. Here we report that STEVOR functions as an erythrocyte-binding protein that recognizes Glycophorin C (GPC) on the red blood cell (RBC) surface and that its binding correlates with the level of GPC on the RBC surface. STEVOR expression on the RBC leads to PfEMP1-independent binding of infected RBCs to uninfected RBCs (rosette formation), while antibodies targeting STEVOR in the merozoite can effectively inhibit invasion. Our results suggest a PfEMP1-independent role for STEVOR in enabling infected erythrocytes at the schizont stage to form rosettes and in promoting merozoite invasion.
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Affiliation(s)
- Makhtar Niang
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Amy Kristine Bei
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Kripa Gopal Madnani
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Shaaretha Pelly
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Selasi Dankwa
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Usheer Kanjee
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Karthigayan Gunalan
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Anburaj Amaladoss
- Singapore-MIT Alliance for Research and Technology (SMART)-Interdisciplinary Research Group in Infectious Diseases, Singapore 117456, Singapore
| | - Kim Pin Yeo
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Ndeye Sakha Bob
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Benoit Malleret
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, National University Health System, Singapore 117545, Singapore; Singapore Immunology Network, A(∗)STAR, Singapore 138648, Singapore
| | - Manoj Theodore Duraisingh
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
| | - Peter Rainer Preiser
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore 637551, Singapore.
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Binding of subdomains 1/2 of PfEMP1-DBL1α to heparan sulfate or heparin mediates Plasmodium falciparum rosetting. PLoS One 2015; 10:e0118898. [PMID: 25742651 PMCID: PMC4351205 DOI: 10.1371/journal.pone.0118898] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 01/20/2015] [Indexed: 11/24/2022] Open
Abstract
The capacity of Plasmodium falciparum parasitized erythrocytes (pRBC) to adhere to the endothelial lining in the microvasculature and to red blood cells (RBC) is associated with the virulence of the parasite, the pathogenesis and development of severe malaria. Rosetting, the binding of uninfected RBC to pRBC, is frequently observed in individuals with severe malaria and is mediated by the N-terminal NTS-DBL1α domain of the adhesin Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) expressed at the surface of the pRBC. Heparan sulfate has been suggested to be an important receptor for the NTS-DBL1α variant IT4var60 expressed by the parasite FCR3S1.2. Here, we have determined the binding site of NTS-DBL1α (IT4var60) to the RBC and heparin using a set of recombinant, mutated proteins expressed in and purified from E. coli. All the variants were studied for their ability to bind to RBC, their capacities to disrupt FCR3S1.2 rosettes, their affinities for heparin and their binding to rosette-disruptive mAbs. Our results suggest that NTS-DBL1α mediates binding to RBC through a limited number of basic amino acid residues localized on the surface of subdomains 1 (SD1) and 2 (SD2). The SD2-binding site is localized in close proximity to one of two previously identified binding sites in the rosetting PfEMP1 of the parasite PaloAlto-varO. The binding site in SD2 of NTS-DBL1α could represent a template for the development of anti-rosetting drugs.
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Albrecht L, Angeletti D, Moll K, Blomqvist K, Valentini D, D'Alexandri FL, Maurer M, Wahlgren M. B-cell epitopes in NTS-DBL1α of PfEMP1 recognized by human antibodies in Rosetting Plasmodium falciparum. PLoS One 2014; 9:e113248. [PMID: 25438249 PMCID: PMC4249881 DOI: 10.1371/journal.pone.0113248] [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: 07/01/2014] [Accepted: 10/21/2014] [Indexed: 11/20/2022] Open
Abstract
Plasmodium falciparum is the most lethal of the human malaria parasites. The virulence is associated with the capacity of the infected red blood cell (iRBC) to sequester inside the deep microvasculature where it may cause obstruction of the blood-flow when binding is excessive. Rosetting, the adherence of the iRBC to uninfected erythrocytes, has been found associated with severe malaria and found to be mediated by the NTS-DBL1α-domain of Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1). Here we show that the reactivity of plasma of Cameroonian children with the surface of the FCR3S1.2-iRBC correlated with the capacity to disrupt rosettes and with the antibody reactivity with a recombinant PfEMP1 (NTS-DBL1α of IT4var60) expressed by parasite FCR3S1.2. The plasma-reactivity in a microarray, consisting of 96 overlapping 15-mer long peptides covering the NTS-DBL1α domain from IT4var60 sequence, was compared with their capacity to disrupt rosettes and we identified five peptides where the reactivity were correlated. Three of the peptides were localized in subdomain-1 and 2. The other two peptide-sequences were localized in the NTS-domain and in subdomain-3. Further, principal component analysis and orthogonal partial least square analysis generated a model that supported these findings. In conclusion, human antibody reactivity with short linear-peptides of NTS-DBL1α of PfEMP1 suggests subdomains 1 and 2 to hold anti-rosetting epitopes recognized by anti-rosetting antibodies. The data suggest rosetting to be mediated by the variable areas of PfEMP1 but also to involve structurally relatively conserved areas of the molecule that may induce biologically active antibodies.
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Affiliation(s)
- Letusa Albrecht
- Department of Microbiology, Tumor- and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- * E-mail: (MW); (LA)
| | - Davide Angeletti
- Department of Microbiology, Tumor- and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Kirsten Moll
- Department of Microbiology, Tumor- and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Karin Blomqvist
- Department of Microbiology, Tumor- and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Davide Valentini
- Therapeutic Immunology (TIM), Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- CAST, Karolinska University Hospital, Huddinge, Sweden
| | | | - Markus Maurer
- Therapeutic Immunology (TIM), Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- CAST, Karolinska University Hospital, Huddinge, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor- and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- * E-mail: (MW); (LA)
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Rosetting Plasmodium falciparum-infected erythrocytes bind to human brain microvascular endothelial cells in vitro, demonstrating a dual adhesion phenotype mediated by distinct P. falciparum erythrocyte membrane protein 1 domains. Infect Immun 2013; 82:949-59. [PMID: 24343658 PMCID: PMC3958005 DOI: 10.1128/iai.01233-13] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adhesion interactions between Plasmodium falciparum-infected erythrocytes (IE) and human cells underlie the pathology of severe malaria. IE cytoadhere to microvascular endothelium or form rosettes with uninfected erythrocytes to survive in vivo by sequestering IE in the microvasculature and avoiding splenic clearance mechanisms. Both rosetting and cytoadherence are mediated by the parasite-derived IE surface protein family Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). Rosetting and cytoadherence have been widely studied as separate entities; however, the ability of rosetting P. falciparum strains to cytoadhere has received little attention. Here, we show that IE of the IT/R29 strain expressing a rosette-mediating PfEMP1 variant (IT4var09) cytoadhere in vitro to a human brain microvascular endothelial cell line (HBEC-5i). Cytoadherence was inhibited by heparin and by treatment of HBEC-5i with heparinase III, suggesting that the endothelial receptors for IE binding are heparan sulfate proteoglycans. Antibodies to the N-terminal regions of the IT4var09 PfEMP1 variant (NTS-DBL1α and DBL2γ domains) specifically inhibited and reversed cytoadherence down to low concentrations (<10 μg/ml of total IgG). Surface plasmon resonance experiments showed that the NTS-DBLα and DBL2γ domains bind strongly to heparin, with half-maximal binding at a concentration of ∼0.5 μM in both cases. Therefore, cytoadherence of IT/R29 IE is distinct from rosetting, which is primarily mediated by NTS-DBL1α interactions with complement receptor 1. These data show that IT4var09-expressing parasites are capable of dual interactions with both endothelial cells and uninfected erythrocytes via distinct receptor-ligand interactions.
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Rorick MM, Rask TS, Baskerville EB, Day KP, Pascual M. Homology blocks of Plasmodium falciparum var genes and clinically distinct forms of severe malaria in a local population. BMC Microbiol 2013; 13:244. [PMID: 24192078 PMCID: PMC3827005 DOI: 10.1186/1471-2180-13-244] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/26/2013] [Indexed: 11/25/2022] Open
Abstract
Background The primary target of the human immune response to the malaria parasite Plasmodium falciparum, P. falciparum erythrocyte membrane protein 1 (PfEMP1), is encoded by the members of the hyper-diverse var gene family. The parasite exhibits antigenic variation via mutually exclusive expression (switching) of the ~60 var genes within its genome. It is thought that different variants exhibit different host endothelial binding preferences that in turn result in different manifestations of disease. Results Var sequences comprise ancient sequence fragments, termed homology blocks (HBs), that recombine at exceedingly high rates. We use HBs to define distinct var types within a local population. We then reanalyze a dataset that contains clinical and var expression data to investigate whether the HBs allow for a description of sequence diversity corresponding to biological function, such that it improves our ability to predict disease phenotype from parasite genetics. We find that even a generic set of HBs, which are defined for a small number of non-local parasites: capture the majority of local sequence diversity; improve our ability to predict disease severity from parasite genetics; and reveal a previously hypothesized yet previously unobserved parasite genetic basis for two forms of severe disease. We find that the expression rates of some HBs correlate more strongly with severe disease phenotypes than the expression rates of classic var DBLα tag types, and principal components of HB expression rate profiles further improve genotype-phenotype models. More specifically, within the large Kenyan dataset that is the focus of this study, we observe that HB expression differs significantly for severe versus mild disease, and for rosetting versus impaired consciousness associated severe disease. The analysis of a second much smaller dataset from Mali suggests that these HB-phenotype associations are consistent across geographically distant populations, since we find evidence suggesting that the same HB-phenotype associations characterize this population as well. Conclusions The distinction between rosetting versus impaired consciousness associated var genes has not been described previously, and it could have important implications for monitoring, intervention and diagnosis. Moreover, our results have the potential to illuminate the molecular mechanisms underlying the complex spectrum of severe disease phenotypes associated with malaria—an important objective given that only about 1% of P. falciparum infections result in severe disease.
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Affiliation(s)
- Mary M Rorick
- Department of Ecology and Evolutionary Biology, University of Michigan, 2019 Kraus Nat, Sci, Bldg,, 830 North University Ave, Ann Arbor 48109-1048, Michigan, USA.
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Berger SS, Turner L, Wang CW, Petersen JEV, Kraft M, Lusingu JPA, Mmbando B, Marquard AM, Bengtsson DBAC, Hviid L, Nielsen MA, Theander TG, Lavstsen T. Plasmodium falciparum expressing domain cassette 5 type PfEMP1 (DC5-PfEMP1) bind PECAM1. PLoS One 2013; 8:e69117. [PMID: 23874884 PMCID: PMC3706608 DOI: 10.1371/journal.pone.0069117] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 06/07/2013] [Indexed: 11/18/2022] Open
Abstract
Members of the Plasmodium falciparum Erythrocyte Membrane protein 1 (PfEMP1) family expressed on the surface of malaria-infected erythrocytes mediate binding of the parasite to different receptors on the vascular lining. This process drives pathologies, and severe childhood malaria has been associated with the expression of particular subsets of PfEMP1 molecules. PfEMP1 are grouped into subtypes based on upstream sequences and the presence of semi-conserved PfEMP1 domain compositions named domain cassettes (DCs). Earlier studies have indicated that DC5-containing PfEMP1 (DC5-PfEMP1) are more likely to be expressed in children with severe malaria disease than in children with uncomplicated malaria, but these PfEMP1 subtypes only dominate in a relatively small proportion of the children with severe disease. In this study, we have characterised the genomic sequence characteristic for DC5, and show that two genetically different parasite lines expressing DC5-PfEMP1 bind PECAM1, and that anti-DC5-specific antibodies inhibit binding of DC5-PfEMP1-expressing parasites to transformed human bone marrow endothelial cells (TrHBMEC). We also show that antibodies against each of the four domains characteristic for DC5 react with native PfEMP1 expressed on the surface of infected erythrocytes, and that some of these antibodies are cross-reactive between the two DC5-containing PfEMP1 molecules tested. Finally, we confirm that anti-DC5 antibodies are acquired early in life by individuals living in malaria endemic areas, that individuals having high levels of these antibodies are less likely to develop febrile malaria episodes and that the antibody levels correlate positively with hemoglobin levels.
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Affiliation(s)
- Sanne S. Berger
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
- * E-mail: (SB); (TL)
| | - Louise Turner
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Christian W. Wang
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Jens E. V. Petersen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Maria Kraft
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - John P. A. Lusingu
- National Institute for Medical Research (NIMR), Tanga Medical Research Centre, Tanga, Tanzania
| | - Bruno Mmbando
- National Institute for Medical Research (NIMR), Tanga Medical Research Centre, Tanga, Tanzania
| | - Andrea M. Marquard
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Dominique B. A. C. Bengtsson
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Lars Hviid
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Morten A. Nielsen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Thor G. Theander
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), University of Copenhagen, Copenhagen, Denmark
- * E-mail: (SB); (TL)
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Analysis of antibody induction upon immunization with distinct NTS-DBL1α-domains of PfEMP1 from rosetting Plasmodium falciparum parasites. Malar J 2013; 12:32. [PMID: 23347690 PMCID: PMC3599323 DOI: 10.1186/1475-2875-12-32] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 01/22/2013] [Indexed: 11/15/2022] Open
Abstract
Background Rosette-formation of Plasmodium falciparum parasitized erythrocytes is of importance in the development of severe malaria. The parasite-derived molecule PfEMP1 (Plasmodium falciparum erythrocyte membrane protein 1), central to rosetting, is suggested to be included in a multimeric vaccine targeting severe disease. Methods Three recombinant NTS-DBL1α-domains of PfEMP1 were generated in Escherichia coli, purified and used for immunization of rats and goats. Antibody titres were determined in ELISA assays and responses were compared in-between different individual animals and species. Reactivity with the parasites was tested in live pRBC using FACS. B-cell epitopes prediction was carried out in silico and compared to the results obtained by peptide microarray. Screening for serological cross-reactivity with heterologous NTS-DBL1α variants was carried out by ELISA, peptide array and FACS on pRBC of different laboratory strains and patient isolates. Results All three NTS-DBL1α-domains induced high titres of antibodies that were biologically active with no apparent difference between constructs covering slightly different parts of the DBL1α-sequence. The different animal species showed comparable titres of antibodies, while variations within individuals of the species could be observed. Mapping of the recognized epitopes revealed that most parts of the molecule were able to induce an antibody response with a tendency for the N and C terminal parts of the molecule for slightly higher recognition. Important differences to the epitopes predicted were found as some of the most conserved parts of the DBL1α-domain contained the main epitopes for antibody reactivity. ELISA assays and peptide microarray demonstrated substantial cross-reactivity to heterologous variants, while binding to native PfEMP1 was observed only in few combinations on the pRBC surface, underlining that mainly internal, conserved and not surface exposed parts of the DBL1α-domain are responsible for this observation. Conclusion Biologically active antibodies can be induced consistently, with high titres, in different animal species and the antibodies elicited by different constructs react with similar epitopes. Induced antibodies recognize epitopes localized in all subdomains of the DBL1α-sequence. Cross-reactivity between NTS-DBL1α-variants is common in ELISA, but rare with live pRBC emphasizing that also internal, conserved areas of PfEMP1 carry important highly immunogenic epitopes of the molecule.
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Blomqvist K, Albrecht L, Quintana MDP, Angeletti D, Joannin N, Chêne A, Moll K, Wahlgren M. A sequence in subdomain 2 of DBL1α of Plasmodium falciparum erythrocyte membrane protein 1 induces strain transcending antibodies. PLoS One 2013; 8:e52679. [PMID: 23335956 PMCID: PMC3546040 DOI: 10.1371/journal.pone.0052679] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 11/19/2012] [Indexed: 11/18/2022] Open
Abstract
Immunity to severe malaria is the first level of immunity acquired to Plasmodium falciparum. Antibodies to the variant antigen PfEMP1 (P. falciparum erythrocyte membrane protein 1) present at the surface of the parasitized red blood cell (pRBC) confer protection by blocking microvascular sequestration. Here we have generated antibodies to peptide sequences of subdomain 2 of PfEMP1-DBL1α previously identified to be associated with severe or mild malaria. A set of sera generated to the amino acid sequence KLQTLTLHQVREYWWALNRKEVWKA, containing the motif ALNRKE, stained the live pRBC. 50% of parasites tested (7/14) were positive both in flow cytometry and immunofluorescence assays with live pRBCs including both laboratory strains and in vitro adapted clinical isolates. Antibodies that reacted selectively with the sequence REYWWALNRKEVWKA in a 15-mer peptide array of DBL1α-domains were also found to react with the pRBC surface. By utilizing a peptide array to map the binding properties of the elicited anti-DBL1α antibodies, the amino acids WxxNRx were found essential for antibody binding. Complementary experiments using 135 degenerate RDSM peptide sequences obtained from 93 Ugandan patient-isolates showed that antibody binding occurred when the amino acids WxLNRKE/D were present in the peptide. The data suggests that the ALNRKE sequence motif, associated with severe malaria, induces strain-transcending antibodies that react with the pRBC surface.
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Affiliation(s)
- Karin Blomqvist
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Letusa Albrecht
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Maria del Pilar Quintana
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Escuela de Medicina y Ciencias de la Salud, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Bogotá, Colombia
| | - Davide Angeletti
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Nicolas Joannin
- Bioinformatics Center, Institute for Chemical Research, Kyoto University, Kyoto, Japan
| | - Arnaud Chêne
- Biologie des interactions Hôte-Parasite, Institut Pasteur, Paris, France
| | - Kirsten Moll
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- * E-mail:
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Angeletti D, Albrecht L, Blomqvist K, Quintana MDP, Akhter T, Bächle SM, Sawyer A, Sandalova T, Achour A, Wahlgren M, Moll K. Plasmodium falciparum rosetting epitopes converge in the SD3-loop of PfEMP1-DBL1α. PLoS One 2012; 7:e50758. [PMID: 23227205 PMCID: PMC3515580 DOI: 10.1371/journal.pone.0050758] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Accepted: 10/25/2012] [Indexed: 11/26/2022] Open
Abstract
The ability of Plasmodium falciparum parasitized RBC (pRBC) to form rosettes with normal RBC is linked to the virulence of the parasite and RBC polymorphisms that weaken rosetting confer protection against severe malaria. The adhesin PfEMP1 mediates the binding and specific antibodies prevent sequestration in the micro-vasculature, as seen in animal models. Here we demonstrate that epitopes targeted by rosette disrupting antibodies converge in the loop of subdomain 3 (SD3) which connects the h6 and h7 α-helices of PfEMP1-DBL1α. Both monoclonal antibodies and polyclonal IgG, that bound to epitopes in the SD3-loop, stained the surface of pRBC, disrupted rosettes and blocked direct binding of recombinant NTS-DBL1α to RBC. Depletion of polyclonal IgG raised to NTS-DBL1α on a SD3 loop-peptide removed the anti-rosetting activity. Immunizations with recombinant subdomain 1 (SD1), subdomain 2 (SD2) or SD3 all generated antibodies reacting with the pRBC-surface but only the sera of animals immunized with SD3 disrupted rosettes. SD3-sequences were found to segregate phylogenetically into two groups (A/B). Group A included rosetting sequences that were associated with two cysteine-residues present in the SD2-domain while group B included those with three or more cysteines. Our results suggest that the SD3 loop of PfEMP1-DBL1α is an important target of anti-rosetting activity, clarifying the molecular basis of the development of variant-specific rosette disrupting antibodies.
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Affiliation(s)
- Davide Angeletti
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Letusa Albrecht
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Karin Blomqvist
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - María del Pilar Quintana
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
- Escuela de Medicina y Ciencias de la Salud, Facultad de Ciencias Naturales y Matemáticas, Universidad del Rosario, Bogotá, Colombia
| | - Tahmina Akhter
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
| | - Susanna M. Bächle
- Center for Infectious Medicine, Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
| | - Alan Sawyer
- EMBL Monoclonal Antibodies Core Facility, Monterotondo-Scalo (RM), Italy
| | - Tatyana Sandalova
- Center for Infectious Medicine, Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
| | - Adnane Achour
- Center for Infectious Medicine, Department of Medicine, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
- * E-mail: (MW); (KM)
| | - Kirsten Moll
- Department of Microbiology, Tumor- and Cellbiology (MTC), Karolinska Institutet, Stockholm, Sweden
- * E-mail: (MW); (KM)
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Structural basis for the ABO blood-group dependence of Plasmodium falciparum rosetting. PLoS Pathog 2012; 8:e1002781. [PMID: 22807674 PMCID: PMC3395597 DOI: 10.1371/journal.ppat.1002781] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 05/15/2012] [Indexed: 11/29/2022] Open
Abstract
The ABO blood group influences susceptibility to severe Plasmodium falciparum malaria. Recent evidence indicates that the protective effect of group O operates by virtue of reduced rosetting of infected red blood cells (iRBCs) with uninfected RBCs. Rosetting is mediated by a subgroup of PfEMP1 adhesins, with RBC binding being assigned to the N-terminal DBL1α1 domain. Here, we identify the ABO blood group as the main receptor for VarO rosetting, with a marked preference for group A over group B, which in turn is preferred to group O RBCs. We show that recombinant NTS-DBL1α1 and NTS-DBL1α1-CIDR1γ reproduce the VarO-iRBC blood group preference and document direct binding to blood group trisaccharides by surface plasmon resonance. More detailed RBC subgroup analysis showed preferred binding to group A1, weaker binding to groups A2 and B, and least binding to groups Ax and O. The 2.8 Å resolution crystal structure of the PfEMP1-VarO Head region, NTS-DBL1α1-CIDR1γ, reveals extensive contacts between the DBL1α1 and CIDR1γ and shows that the NTS-DBL1α1 hinge region is essential for RBC binding. Computer docking of the blood group trisaccharides and subsequent site-directed mutagenesis localized the RBC-binding site to the face opposite to the heparin-binding site of NTS-DBLα1. RBC binding involves residues that are conserved between rosette-forming PfEMP1 adhesins, opening novel opportunities for intervention against severe malaria. By deciphering the structural basis of blood group preferences in rosetting, we provide a link between ABO blood grouppolymorphisms and rosette-forming adhesins, consistent with the selective role of falciparum malaria on human genetic makeup. Rosetting, the capacity of infected red blood cells (RBCs) to bind uninfected RBCs, is a Plasmodium falciparum virulence factor. Rosetting is influenced by the ABO blood group, being less efficient with O RBCs. Although this preference may account for protection against severe malaria afforded by the O blood group, its understanding is fragmentary. We identify the ABO blood group as the main receptor for the rosetting Palo Alto VarO parasites, which display a marked preference for blood group A. Rosetting is caused by a sub-group of PfEMP1 adhesins. PfEMP1-VarO shares with other rosetting lines a specific NTS-DBL1α1-CIDR1γ Head region. We show that the Head region binds RBCs more efficiently than NTS-DBL1α1 and that ABO blood group polymorphisms influence binding of both domains. The 2.8 Å resolution crystal structure of the Head region reveals extensive contacts between the DBL1α1 and CIDR1γ domains, and shows structural features of the NTS-DBL1α1 hinge region essential for RBC binding. We localize the RBC-binding site to the face opposite to the heparin-binding site of NTS-DBL1α1 and document direct binding of the Head region to A and B trisaccharides These findings provide novel insights into the interactions established by malaria parasites with a prominent human blood group.
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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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35
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Ghumra A, Semblat JP, Ataide R, Kifude C, Adams Y, Claessens A, Anong DN, Bull PC, Fennell C, Arman M, Amambua-Ngwa A, Walther M, Conway DJ, Kassambara L, Doumbo OK, Raza A, Rowe JA. Induction of strain-transcending antibodies against Group A PfEMP1 surface antigens from virulent malaria parasites. PLoS Pathog 2012; 8:e1002665. [PMID: 22532802 PMCID: PMC3330128 DOI: 10.1371/journal.ppat.1002665] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2011] [Accepted: 03/08/2012] [Indexed: 12/22/2022] Open
Abstract
Sequence diversity in pathogen antigens is an obstacle to the development of interventions against many infectious diseases. In malaria caused by Plasmodium falciparum, the PfEMP1 family of variant surface antigens encoded by var genes are adhesion molecules that play a pivotal role in malaria pathogenesis and clinical disease. PfEMP1 is a major target of protective immunity, however, development of drugs or vaccines based on PfEMP1 is problematic due to extensive sequence diversity within the PfEMP1 family. Here we identified the PfEMP1 variants transcribed by P. falciparum strains selected for a virulence-associated adhesion phenotype (IgM-positive rosetting). The parasites transcribed a subset of Group A PfEMP1 variants characterised by an unusual PfEMP1 architecture and a distinct N-terminal domain (either DBLα1.5 or DBLα1.8 type). Antibodies raised in rabbits against the N-terminal domains showed functional activity (surface reactivity with live infected erythrocytes (IEs), rosette inhibition and induction of phagocytosis of IEs) down to low concentrations (<10 µg/ml of total IgG) against homologous parasites. Furthermore, the antibodies showed broad cross-reactivity against heterologous parasite strains with the same rosetting phenotype, including clinical isolates from four sub-Saharan African countries that showed surface reactivity with either DBLα1.5 antibodies (variant HB3var6) or DBLα1.8 antibodies (variant TM284var1). These data show that parasites with a virulence-associated adhesion phenotype share IE surface epitopes that can be targeted by strain-transcending antibodies to PfEMP1. The existence of shared surface epitopes amongst functionally similar disease-associated P. falciparum parasite isolates suggests that development of therapeutic interventions to prevent severe malaria is a realistic goal. Malaria remains one of the world's most deadly diseases. Life-threatening malaria is linked to a process called rosetting, in which malaria parasite-infected red blood cells bind to uninfected red cells to form aggregates that block blood flow in vital organs such as the brain. Current efforts to develop drugs or vaccines against rosetting are hindered by variation in the parasite rosette-mediating proteins, found on the surface of infected red cells. We studied these parasite-derived surface proteins and discovered that although they are variable, they share some common features. We raised antibodies against the rosette-mediating proteins, and found that they cross-reacted with multiple rosetting parasite strains from different countries around the world, including samples collected directly from African children with severe malaria. These findings provide new insights into malaria parasite interactions with human cells, and provide proof of principle that variable parasite molecules from virulent malaria parasites can induce strain-transcending antibodies. Hence, this work provides the foundation for the development of new therapies to treat or prevent life-threatening malaria.
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Affiliation(s)
- Ashfaq Ghumra
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jean-Philippe Semblat
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ricardo Ataide
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Carolyne Kifude
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Yvonne Adams
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Antoine Claessens
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Damian N. Anong
- Biotechnology Unit, Faculty of Science, University of Buea, Buea, Cameroon
| | - Peter C. Bull
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Clare Fennell
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Monica Arman
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Michael Walther
- Medical Research Council Laboratories, Fajara, Banjul, The Gambia
| | - David J. Conway
- Medical Research Council Laboratories, Fajara, Banjul, The Gambia
| | - Lalla Kassambara
- Malaria Research and Training Centre, University of Bamako, Bamako, Mali
| | - Ogobara K. Doumbo
- Malaria Research and Training Centre, University of Bamako, Bamako, Mali
| | - Ahmed Raza
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - J. Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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