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Kassa MW, Hasang W, Barateiro A, Damelang T, Brewster J, Dombrowski JG, Longley RJ, Chung AW, Wunderlich G, Mueller I, Aitken EH, Marinho CRF, Rogerson SJ. Acquisition of antibodies to Plasmodium falciparum and Plasmodium vivax antigens in pregnant women living in a low malaria transmission area of Brazil. Malar J 2022; 21:360. [PMID: 36457056 PMCID: PMC9714246 DOI: 10.1186/s12936-022-04402-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 11/25/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Pregnant women have increased susceptibility to Plasmodium falciparum malaria and acquire protective antibodies over successive pregnancies. Most studies that investigated malaria antibody responses in pregnant women are from high transmission areas in sub-Saharan Africa, while reports from Latin America are scarce and inconsistent. The present study sought to explore the development of antibodies against P. falciparum and Plasmodium vivax antigens in pregnant women living in a low transmission area in the Brazilian Amazon. METHODS In a prospective cohort study, plasma samples from 408 pregnant women (of whom 111 were infected with P. falciparum, 96 had infections with P. falciparum and P. vivax, and 201 had no Plasmodium infection) were used to measure antibody levels. Levels of IgG and opsonizing antibody to pregnancy-specific variant surface antigens (VSAs) on infected erythrocytes (IEs), 10 recombinant VAR2CSA Duffy binding like (DBL domains), 10 non-pregnancy-specific P. falciparum merozoite antigens, and 10 P. vivax antigens were measured by flow cytometry, ELISA, and multiplex assays. Antibody levels and seropositivity among the groups were compared. RESULTS Antibodies to VSAs on P. falciparum IEs were generally low but were higher in currently infected women and women with multiple P. falciparum episodes over pregnancy. Many women (21%-69%) had antibodies against each individual VAR2CSA DBL domain, and antibodies to DBLs correlated with each other (r ≥ 0.55, p < 0.0001), but not with antibody to VSA or history of infection. Infection with either malaria species was associated with higher seropositivity rate for antibodies against P. vivax proteins, adjusted odds ratios (95% CI) ranged from 5.6 (3.2, 9.7), p < 0.0001 for PVDBPII-Sal1 to 15.7 (8.3, 29.7), p < 0.0001 for PvTRAg_2. CONCLUSIONS Pregnant Brazilian women had low levels of antibodies to pregnancy-specific VSAs that increased with exposure. They frequently recognized both VAR2CSA DBL domains and P. vivax antigens, but only the latter varied with infection. Apparent antibody prevalence is highly dependent on the assay platform used.
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Affiliation(s)
- Meseret W. Kassa
- grid.1008.90000 0001 2179 088XDepartment of Medicine, University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Level 5, 792 Elizabeth St, University of Melbourne, Melbourne, VIC 3000 Australia
| | - Wina Hasang
- grid.1008.90000 0001 2179 088XDepartment of Infectious Diseases, University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC Australia
| | - André Barateiro
- grid.11899.380000 0004 1937 0722Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Timon Damelang
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, University of Melbourne, Melbourne, VIC Australia
| | - Jessica Brewster
- grid.1042.70000 0004 0432 4889Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC Australia
| | - Jamille G. Dombrowski
- grid.11899.380000 0004 1937 0722Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rhea J. Longley
- grid.1042.70000 0004 0432 4889Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, University of Melbourne, Melbourne, VIC Australia
| | - Amy W. Chung
- grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, University of Melbourne, Melbourne, VIC Australia
| | - Gerhard Wunderlich
- grid.11899.380000 0004 1937 0722Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Ivo Mueller
- grid.1042.70000 0004 0432 4889Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, University of Melbourne, Melbourne, VIC Australia
| | - Elizabeth H. Aitken
- grid.1008.90000 0001 2179 088XDepartment of Infectious Diseases, University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC Australia ,grid.1008.90000 0001 2179 088XDepartment of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, University of Melbourne, Melbourne, VIC Australia
| | - Claudio R. F. Marinho
- grid.11899.380000 0004 1937 0722Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Stephen J. Rogerson
- grid.1008.90000 0001 2179 088XDepartment of Medicine, University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Level 5, 792 Elizabeth St, University of Melbourne, Melbourne, VIC 3000 Australia ,grid.1008.90000 0001 2179 088XDepartment of Infectious Diseases, University of Melbourne, The Peter Doherty Institute for Infection and Immunity, Melbourne, VIC Australia
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2
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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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3
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Optimization of in vitro trophoblast assay for real-time impedimetric sensing of trophoblast-erythrocyte interactions in Plasmodium falciparum malaria. Anal Bioanal Chem 2020; 412:3915-3923. [PMID: 31989195 DOI: 10.1007/s00216-020-02413-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/20/2019] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
Abstract
Sequestration of Plasmodium falciparum-infected erythrocytes (IEs) is responsible for the pathophysiology of placental malaria, leading to serious complications such as intrauterine growth restriction and low birth weight. However, it is an experimental challenge to study the biology of human placenta. Conventional cell culture-based in vitro placental models rely on immunostaining techniques and high-magnification microscopy is limited in providing real-time quantitative analysis. Impedimetric sensing in combination with cell culture may offer a useful tool. In this paper, we report that real-time label-free measurement of cellular electrical impedance using xCELLigence technology can be used to quantify the proliferation, syncytial fusion, and long-term response of BeWo cells to IEs cytoadhesion. Specifically, we optimized key experimental parameters of cell seeding density and concentration of forskolin, a compound used to promote cell syncitiation, based on electrical signals and immunostaining results. Prolonged time of infection with IEs that led to cell-cell junction vanishment in BeWo cells and release of inflammatory cytokines were monitored in real time by continuous change in electrical impedance. The results suggest that the impedimetric technique is sensitive and can offer new opportunities for the study of cellular responses of trophoblast cells to IEs. The developed system can provide potentially a high-throughput screening tool of anti-adhesion or anti-inflammatory drugs for placental malaria infections.
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Hempel C. Cryo scanning electron microscopy of Plasmodium falciparum-infected erythrocytes. APMIS 2017; 125:650-654. [PMID: 28493454 DOI: 10.1111/apm.12699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 02/27/2017] [Indexed: 11/29/2022]
Abstract
Plasmodium falciparum invades erythrocytes as an essential part of their life cycle. While living inside erythrocytes, the parasite remodels the cell's intracellular organization as well as its outer surface. Late trophozoite-stage parasites and schizonts introduce numerous small protrusions on the erythrocyte surface, called knobs. Current methods for studying these knobs include atomic force microscopy and electron microscopy. Standard electron microscopy methods rely on chemical fixation and dehydration modifying cell size. Here, a novel method is presented using rapid freezing and scanning electron microscopy under cryogenic conditions allowing for high resolution and magnification of erythrocytes. This novel technique can be used for precise estimates of knob density and for studies on cytoadhesion.
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Affiliation(s)
- Casper Hempel
- Centre for Medical Parasitology, Department of Clinical Microbiology, Copenhagen University Hospital, Denmark.,Department of Immunology and Microbiology, University of Copenhagen, Copenhagen N, Denmark.,Department of Micro- and Nanotechnology, Technical University of Denmark, Denmark
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5
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Hempel C, Wang CW, Kurtzhals JAL, Staalsø T. Binding of Plasmodium falciparum to CD36 can be shielded by the glycocalyx. Malar J 2017; 16:193. [PMID: 28486940 PMCID: PMC5424350 DOI: 10.1186/s12936-017-1844-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 04/27/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Plasmodium falciparum-infected erythrocytes sequester in the microcirculation due to interaction between surface-expressed parasite proteins and endothelial receptors. Endothelial cells are covered in a carbohydrate-rich glycocalyx that shields against undesired leukocyte adhesion. It was investigated if the cellular glycocalyx affects the binding of P. falciparum-infected erythrocytes to CD36 in vitro. METHODS Glycocalyx growth was followed in vitro by using azido sugars and cationized ferritin detecting O-glycoproteins and negatively charged proteoglycans, respectively. P. falciparum (clone FCR3/IT) was selected on Chinese hamster ovary (CHO) cells transfected with human CD36. Cytoadhesion to CHO CD36 at 1-4 days after seeding was quantified by using a static binding assay. RESULTS The glycocalyx thickness of CHO cells increased during 4 days in culture as assessed by metabolic labelling of glycans with azido sugars and with electron microscopy studying the binding of cationized ferritin to cell surfaces. The functional importance of this process was addressed in binding assays by using CHO cells transfected with CD36. In parallel with the maturation of the glycocalyx, antibody-binding to CD36 was inhibited, despite stable expression of CD36. P. falciparum selected for CD36-binding recognized CD36 on CHO cells on the first day in culture, but the binding was lost after 2-4 days. CONCLUSION The endothelial glycocalyx affects parasite cytoadhesion in vitro, an effect that has previously been ignored. The previously reported loss of glycocalyx during experimental malaria may play an important role in the pathogenesis of malaria complications by allowing the close interaction between infected erythrocytes and endothelial receptors.
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Affiliation(s)
- Casper Hempel
- Department of Clinical Microbiology, Centre for Medical Parasitology, Copenhagen University Hospital, Copenhagen, Denmark. .,Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Department of Micro- and Nanotechnology, Technical University of Denmark, Kongens Lyngby, Denmark.
| | - Christian William Wang
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Rigshospitalet, Copenhagen, Denmark
| | - Jørgen Anders Lindholm Kurtzhals
- Department of Clinical Microbiology, Centre for Medical Parasitology, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Trine Staalsø
- Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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6
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Agerbæk MØ, Pereira MA, Clausen TM, Pehrson C, Oo HZ, Spliid C, Rich JR, Fung V, Nkrumah F, Neequaye J, Biggar RJ, Reynolds SJ, Tosato G, Pullarkat ST, Ayers LW, Theander TG, Daugaard M, Bhatia K, Nielsen MA, Mbulaiteye SM, Salanti A. Burkitt lymphoma expresses oncofetal chondroitin sulfate without being a reservoir for placental malaria sequestration. Int J Cancer 2017; 140:1597-1608. [PMID: 27997697 PMCID: PMC5318225 DOI: 10.1002/ijc.30575] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 12/02/2016] [Indexed: 12/22/2022]
Abstract
Burkitt lymphoma (BL) is a malignant disease, which is frequently found in areas with holoendemic Plasmodium falciparum malaria. We have previously found that the VAR2CSA protein is present on malaria-infected erythrocytes and facilitates a highly specific binding to the placenta. ofCS is absent in other non-malignant tissues and thus VAR2CSA generally facilitates parasite sequestration and accumulation in pregnant women. In this study, we show that the specific receptor for VAR2CSA, the oncofetal chondroitin sulfate (ofCS), is likewise present in BL tissue and cell lines. We therefore explored whether ofCS in BL could act as anchor site for VAR2CSA-expressing infected erythrocytes. In contrast to the placenta, we found no evidence of in vivo sequestering of infected erythrocytes in the BL tissue. Furthermore, we found VAR2CSA-specific antibody titers in children with endemic BL to be lower than in control children from the same malaria endemic region. The abundant presence of ofCS in BL tissue and the absence of ofCS in non-malignant tissue encouraged us to examine whether recombinant VAR2CSA could be used to target BL. We confirmed the binding of VAR2CSA to BL-derived cells and showed that a VAR2CSA drug conjugate efficiently killed the BL-derived cell lines in vitro. These results identify ofCS as a novel therapeutic BL target and highlight how VAR2CSA could be used as a tool for the discovery of novel approaches for directing BL therapy.
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Affiliation(s)
- Mette Ø. Agerbæk
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Marina A. Pereira
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Thomas M. Clausen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
- Vancouver Prostate Centre, Vancouver, BC V6H 3Z6, Canada
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC V6H 3Z6, Canada
| | - Caroline Pehrson
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Htoo Zarni Oo
- Vancouver Prostate Centre, Vancouver, BC V6H 3Z6, Canada
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC V6H 3Z6, Canada
| | - Charlotte Spliid
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | | | | | | | - Janet Neequaye
- Department of Child Health, Korle Bu University Teaching Hospital, Accra, Ghana
| | - Robert J. Biggar
- Institute of Health and Biotechnology, Queensland University of Technology, Brisbane, Australia
| | - Steven J. Reynolds
- Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Giovanna Tosato
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Sheeja T. Pullarkat
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles
| | - Leona W. Ayers
- Department of Pathology, The Ohio State University, Columbus, Ohio
| | - Thor G. Theander
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Mads Daugaard
- Vancouver Prostate Centre, Vancouver, BC V6H 3Z6, Canada
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC V6H 3Z6, Canada
| | - Kishor Bhatia
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland
| | - Morten A. Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | | | - Ali Salanti
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
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7
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Novel adenovirus encoded virus-like particles displaying the placental malaria associated VAR2CSA antigen. Vaccine 2017; 35:1140-1147. [PMID: 28131394 DOI: 10.1016/j.vaccine.2017.01.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 01/04/2017] [Accepted: 01/09/2017] [Indexed: 12/13/2022]
Abstract
The malaria parasite Plasmodium falciparum presents antigens on the infected erythrocyte surface that bind human receptors expressed on the vascular endothelium. The VAR2CSA mediated binding to a distinct chondroitin sulphate A (CSA) is a crucial step in the pathophysiology of placental malaria and the CSA binding region of VAR2CSA has been identified as a promising vaccine target against placental malaria. Here we designed adenovirus encoded virus-like particles (VLP) by co-encoding Simian Immunodeficiency Virus (SIV) gag and VAR2CSA. The VAR2CSA antigen was fused to the transmembrane (TM) and cytoplasmic tail (CT) domains of either the envelope protein of mouse mammary tumour virus (MMTV) or the hemagglutinin (HA) of influenza A. For a non-VLP incorporation control, a third design was made where VAR2CSA was expressed without TM-CT domains. In the primary immunogenicity study in Balb/c mice, VAR2CSA fused to HA TM-CT was significantly superior in inducing ID1-ID2a specific antibodies after the first immunization. A sequential study was performed to include a comparison to the soluble VAR2CSA protein vaccine, which has entered a phase I clinical trial (NCT02647489). The results revealed the induction of higher antibody responses and increased inhibition of parasite binding to CSA using either VAR2CSA HA TM-CT or VAR2CSA MMTV TM-CT as priming vaccines for protein double-boost immunizations, compared to protein prime-double boost regimen. Analysis of pooled serum samples on peptide arrays revealed a unique targeting of several epitopes in mice that had been primed with VAR2CSA HA TM-CT. Consequently, modification of VLP anchors is an important point of optimization in virus-encoded retroviral VLP-based vaccines, and adenovirus VLPs boosted by recombinant proteins offer hope of increasing the levels of protective VAR2CSA specific antibodies.
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8
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Pehrson C, Heno KK, Adams Y, Resende M, Mathiesen L, Soegaard M, de Jongh WA, Theander TG, Salanti A, Nielsen MA. Comparison of functional assays used in the clinical development of a placental malaria vaccine. Vaccine 2016; 35:610-618. [PMID: 28012775 DOI: 10.1016/j.vaccine.2016.12.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 12/05/2016] [Accepted: 12/08/2016] [Indexed: 01/06/2023]
Abstract
BACKGROUND Malaria in pregnancy is associated with significant morbidity in pregnant women and their offspring. Plasmodium falciparum infected erythrocytes (IE) express VAR2CSA that mediates binding to chondroitin sulphate A (CSA) in the placenta. Two VAR2CSA-based vaccines for placental malaria are in clinical development. The purpose of this study was to evaluate the robustness and comparability of binding inhibition assays used in the clinical development of placental malaria vaccines. METHODS The ability of sera from animals immunised with different VAR2CSA constructs to inhibit IE binding to CSA was investigated in three in vitro assays using 96-well plates, petri dishes, capillary flow and an ex vivo placental perfusion assay. RESULTS The inter-assay variation was not uniform between assays and ranged from above ten-fold in the flow assay to two-fold in the perfusion assay. The intra-assay variation was highest in the petri dish assay. A positive correlation between IE binding avidity and the level of binding after antibody inhibition in the petri dish assay indicate that high avidity IE binding is more difficult to inhibit. The highest binding inhibition sensitivity was found in the 96-well and petri dish assays compared to the flow and perfusion assays where binding inhibition required higher antibody titers. CONCLUSIONS The inhibitory capacity of antibodies is not easily translated between assays and the high sensitivity of the 96-well and petri dish assays stresses the need for comparing serial dilutions of serum. Furthermore, IE binding avidity must be in the same range when comparing data from different days. There was an overall concordance in the capacity of antibody-mediated inhibition, when comparing the in vitro assays with the perfusion assay, which more closely represents in vivo conditions. Importantly the ID1-ID2a protein in a liposomal formulation, currently in a phase I trial, effectively induced antibodies that inhibited IE adhesion in placental tissue.
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Affiliation(s)
- Caroline Pehrson
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Kristine K Heno
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Yvonne Adams
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Line Mathiesen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353 Copenhagen, Denmark.
| | - Max Soegaard
- ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
| | - Willem A de Jongh
- ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark.
| | - Thor G Theander
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Ali Salanti
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
| | - Morten A Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Denmark.
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9
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Ayres Pereira M, Mandel Clausen T, Pehrson C, Mao Y, Resende M, Daugaard M, Riis Kristensen A, Spliid C, Mathiesen L, E. Knudsen L, Damm P, G. Theander T, R. Hansson S, A. Nielsen M, Salanti A. Placental Sequestration of Plasmodium falciparum Malaria Parasites Is Mediated by the Interaction Between VAR2CSA and Chondroitin Sulfate A on Syndecan-1. PLoS Pathog 2016; 12:e1005831. [PMID: 27556547 PMCID: PMC4996535 DOI: 10.1371/journal.ppat.1005831] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 07/28/2016] [Indexed: 02/07/2023] Open
Abstract
During placental malaria, Plasmodium falciparum infected erythrocytes sequester in the placenta, causing health problems for both the mother and fetus. The specific adherence is mediated by the VAR2CSA protein, which binds to placental chondroitin sulfate (CS) on chondroitin sulfate proteoglycans (CSPGs) in the placental syncytium. However, the identity of the CSPG core protein and the cellular impact of the interaction have remain elusive. In this study we identified the specific CSPG core protein to which the CS is attached, and characterized its exact placental location. VAR2CSA pull-down experiments using placental extracts from whole placenta or syncytiotrophoblast microvillous cell membranes showed three distinct CSPGs available for VAR2CSA adherence. Further examination of these three CSPGs by immunofluorescence and proximity ligation assays showed that syndecan-1 is the main receptor for VAR2CSA mediated placental adherence. We further show that the commonly used placental choriocarcinoma cell line, BeWo, express a different set of proteoglycans than those present on placental syncytiotrophoblast and may not be the most biologically relevant model to study placental malaria. Syncytial fusion of the BeWo cells, triggered by forskolin treatment, caused an increased expression of placental CS-modified syndecan-1. In line with this, we show that rVAR2 binding to placental CS impairs syndecan-1-related Src signaling in forskolin treated BeWo cells, but not in untreated cells. Plasmodium falciparum is the most deadly malaria parasite, causing more than 500,000 deaths each year. The parasite infects the host’s red blood cells. In placental malaria infected red blood cells accumulate in placenta. The parasite protein VAR2CSA mediates this adherence, which causes complications for both mother and child. VAR2CSA binds a carbohydrate chain termed chondroitin sulfate (CS). CS is not a well-defined biochemical entity but constitute a family of oligosaccharides which each have unique sulfation patterns. The CS binding VAR2CSA is attached to proteoglycans expressed on the surface of placental cells. While much work has gone into understanding the nature of VAR2CSA and its interaction with placental CS, the protein to which the placental CS is attached is not known. To further the understanding of the molecular pathology of PM we characterized the CSPG receptor that the parasites adhere to by defining the exact proteoglycan that carries the placental CS. We further investigated the molecular and cellular consequences of VAR2CSA binding to the receptor. This work provides novel insights into the pathology of placental malaria and the nature of the parasite receptor. This may aid development of strategies to treat or prevent placental malaria.
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Affiliation(s)
- Marina Ayres Pereira
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
| | - Thomas Mandel Clausen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
- Vancouver Prostate Centre, Vancouver, BC, Canada
- * E-mail: (TMC); (AS)
| | - Caroline Pehrson
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
| | - Yang Mao
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Copenhagen Center for Glycomics and Department of Cellular and Molecular Medicine, University of Copenhagen, Denmark
| | - Mafalda Resende
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
| | | | | | - Charlotte Spliid
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
| | - Line Mathiesen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Lisbeth E. Knudsen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Peter Damm
- Department of Obstetrics, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thor G. Theander
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
| | - Stefan R. Hansson
- Division of Obstetrics and Gynecology, Department of Clinical Sciences, Lund University Hospital, Lund University, Lund, Sweden
| | - Morten A. Nielsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen and Copenhagen University Hospital, Denmark
- * E-mail: (TMC); (AS)
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10
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Pehrson C, Mathiesen L, Heno KK, Salanti A, Resende M, Dzikowski R, Damm P, Hansson SR, King CL, Schneider H, Wang CW, Lavstsen T, Theander TG, Knudsen LE, Nielsen MA. Adhesion of Plasmodium falciparum infected erythrocytes in ex vivo perfused placental tissue: a novel model of placental malaria. Malar J 2016; 15:292. [PMID: 27230523 PMCID: PMC4881162 DOI: 10.1186/s12936-016-1342-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 05/12/2016] [Indexed: 11/10/2022] Open
Abstract
Background Placental malaria occurs when Plasmodium falciparum infected erythrocytes sequester in the placenta. Placental parasite isolates bind to chondroitin sulphate A (CSA) by expression of VAR2CSA on the surface of infected erythrocytes, but may sequester by other VAR2CSA mediated mechanisms, such as binding to immunoglobulins. Furthermore, other parasite antigens have been associated with placental malaria. These findings have important implications for placental malaria vaccine design. The objective of this study was to adapt and describe a biologically relevant model of parasite adhesion in intact placental tissue. Results The ex vivo placental perfusion model was modified to study adhesion of infected erythrocytes binding to CSA, endothelial protein C receptor (EPCR) or a transgenic parasite where P. falciparum erythrocyte membrane protein 1 expression had been shut down. Infected erythrocytes expressing VAR2CSA accumulated in perfused placental tissue whereas the EPCR binding and the transgenic parasite did not. Soluble CSA and antibodies specific against VAR2CSA inhibited binding of infected erythrocytes. Conclusion The ex vivo model provides a novel way of studying receptor-ligand interactions and antibody mediated inhibition of binding in placental malaria. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1342-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Caroline Pehrson
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
| | - Line Mathiesen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353, Copenhagen, Denmark
| | - Kristine K Heno
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ron Dzikowski
- Department of Microbiology and Molecular Genetics, The Institute for Medical Research Israel-Canada, The Kuvin Center for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, 91120, Jerusalem, Israel
| | - Peter Damm
- Department of Obstetrics, Rigshospitalet, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark
| | - Stefan R Hansson
- Division of Obstetrics and Gynecology, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Christopher L King
- Center for Global Health and Diseases, Case Western Reserve University and Veterans Affairs Medical Center, Cleveland, USA
| | - Henning Schneider
- Department of Obstetrics and Gynecology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Christian W Wang
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thomas Lavstsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thor G Theander
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lisbeth E Knudsen
- Section of Environmental Health, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5A, 1353, Copenhagen, Denmark
| | - Morten A Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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11
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Thrane S, Janitzek CM, Matondo S, Resende M, Gustavsson T, de Jongh WA, Clemmensen S, Roeffen W, van de Vegte-Bolmer M, van Gemert GJ, Sauerwein R, Schiller JT, Nielsen MA, Theander TG, Salanti A, Sander AF. Bacterial superglue enables easy development of efficient virus-like particle based vaccines. J Nanobiotechnology 2016; 14:30. [PMID: 27117585 PMCID: PMC4847360 DOI: 10.1186/s12951-016-0181-1] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/01/2016] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Virus-like particles (VLPs) represent a significant advance in the development of subunit vaccines, combining high safety and efficacy. Their particulate nature and dense repetitive subunit organization makes them ideal scaffolds for display of vaccine antigens. Traditional approaches for VLP-based antigen display require labor-intensive trial-and-error optimization, and often fail to generate dense antigen display. Here we utilize the split-intein (SpyTag/SpyCatcher) conjugation system to generate stable isopeptide bound antigen-VLP complexes by simply mixing of the antigen and VLP components. RESULTS Genetic fusion of SpyTag or SpyCatcher to the N-terminus and/or C-terminus of the Acinetobacter phage AP205 capsid protein resulted in formation of stable, nonaggregated VLPs expressing one SpyCatcher, one SpyTag or two SpyTags per capsid protein. Mixing of spy-VLPs with eleven different vaccine antigens fused to SpyCatcher or SpyTag resulted in formation of antigen-VLP complexes with coupling efficiencies (% occupancy of total VLP binding sites) ranging from 22-88 %. In mice, spy-VLP vaccines presenting the malaria proteins Pfs25 or VAR2CSA markedly increased antibody titer, affinity, longevity and functional efficacy compared to corresponding vaccines employing monomeric proteins. The spy-VLP vaccines also effectively broke B cell self-tolerance and induced potent and durable antibody responses upon vaccination with cancer or allergy-associated self-antigens (PD-L1, CTLA-4 and IL-5). CONCLUSIONS The spy-VLP system constitutes a versatile and rapid method to develop highly immunogenic VLP-based vaccines. Our data provide proof-of-concept for the technology's ability to present complex vaccine antigens to the immune system and elicit robust functional antibody responses as well as to efficiently break B cell self-tolerance. The spy-VLP-system may serve as a generic tool for the cost-effective development of effective VLP-vaccines against both infectious- and non-communicable diseases and could facilitate rapid and unbiased screening of vaccine candidate antigens.
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Affiliation(s)
- Susan Thrane
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Christoph M Janitzek
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Sungwa Matondo
- Kilimanjaro Clinical Research Institute, KCMC, Moshi, Tanzania
| | - Mafalda Resende
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Tobias Gustavsson
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | | | - Stine Clemmensen
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark.,ExpreS2ion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark
| | - Will Roeffen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Geert Jan van Gemert
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - John T Schiller
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Morten A Nielsen
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Thor G Theander
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. .,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark.
| | - Adam F Sander
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. .,Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark.
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12
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Lecarpentier E, Bhatt M, Bertin GI, Deloison B, Salomon LJ, Deloron P, Fournier T, Barakat AI, Tsatsaris V. Computational Fluid Dynamic Simulations of Maternal Circulation: Wall Shear Stress in the Human Placenta and Its Biological Implications. PLoS One 2016; 11:e0147262. [PMID: 26815115 PMCID: PMC4729471 DOI: 10.1371/journal.pone.0147262] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 01/02/2016] [Indexed: 11/20/2022] Open
Abstract
Introduction In the human placenta the maternal blood circulates in the intervillous space (IVS). The syncytiotrophoblast (STB) is in direct contact with maternal blood. The wall shear stress (WSS) exerted by the maternal blood flow on the STB has not been evaluated. Our objective was to determine the physiological WSS exerted on the surface of the STB during the third trimester of pregnancy. Material and Methods To gain insight into the shear stress levels that the STB is expected to experience in vivo, we have formulated three different computational models of varying levels of complexity that reflect different physical representations of the IVS. Computations of the flow fields in all models were performed using the CFD module of the finite element code COMSOL Multiphysics 4.4. The mean velocity of maternal blood in the IVS during the third trimester was measured in vivo with dynamic MRI (0.94±0.14 mm.s-1). To investigate if the in silico results are consistent with physiological observations, we studied the cytoadhesion of human parasitized (Plasmodium falciparum) erythrocytes to primary human STB cultures, in flow conditions with different WSS values. Results The WSS applied to the STB is highly heterogeneous in the IVS. The estimated average values are relatively low (0.5±0.2 to 2.3±1.1 dyn.cm-2). The increase of WSS from 0.15 to 5 dyn.cm-2 was associated with a significant decrease of infected erythrocyte cytoadhesion. No cytoadhesion of infected erythrocytes was observed above 5 dyn.cm-2 applied for one hour. Conclusion Our study provides for the first time a WSS estimation in the maternal placental circulation. In spite of high maternal blood flow rates, the average WSS applied at the surface of the chorionic villi is low (<5 dyn.cm-2). These results provide the basis for future physiologically-relevant in vitro studies of the biological effects of WSS on the STB.
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Affiliation(s)
- E. Lecarpentier
- INSERM, UMR-S 1139, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- Port Royal Maternity, Department of Gynecology Obstetrics I, Centre Hospitalier Universitaire Cochin Broca Hôtel Dieu, Groupe Hospitalier Universitaire Ouest, Assistance Publique-Hôpital de Paris, Paris, France
- DHU Risques et grossesse, Paris, France
- PremUP Foundation, Paris, France
- * E-mail:
| | - M. Bhatt
- Laboratoire d'Hydrodynamique (LadHyX), CNRS, École Polytechnique, 91128, Palaiseau, France
| | - G. I. Bertin
- Institut de Recherche pour le Développement (IRD), MERIT - UMR216, Paris, France
| | - B. Deloison
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- INSERM U970, Paris Cardiovascular Research Center-PARCC, Paris, France
- EA FETUS 7328, Paris, France
- Department of Obstetrics and Fetal Medicine, Paris Descartes University, Hôpital Necker-Enfants-Malades, Assistance Publique-Hôpital de Paris, Paris, France
| | - L. J. Salomon
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- INSERM U970, Paris Cardiovascular Research Center-PARCC, Paris, France
- EA FETUS 7328, Paris, France
- Department of Obstetrics and Fetal Medicine, Paris Descartes University, Hôpital Necker-Enfants-Malades, Assistance Publique-Hôpital de Paris, Paris, France
| | - P. Deloron
- Institut de Recherche pour le Développement (IRD), MERIT - UMR216, Paris, France
| | - T. Fournier
- INSERM, UMR-S 1139, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- DHU Risques et grossesse, Paris, France
- PremUP Foundation, Paris, France
| | - A. I. Barakat
- Laboratoire d'Hydrodynamique (LadHyX), CNRS, École Polytechnique, 91128, Palaiseau, France
| | - V. Tsatsaris
- INSERM, UMR-S 1139, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- Port Royal Maternity, Department of Gynecology Obstetrics I, Centre Hospitalier Universitaire Cochin Broca Hôtel Dieu, Groupe Hospitalier Universitaire Ouest, Assistance Publique-Hôpital de Paris, Paris, France
- DHU Risques et grossesse, Paris, France
- PremUP Foundation, Paris, France
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13
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Ndam NT, Denoeud-Ndam L, Doritchamou J, Viwami F, Salanti A, Nielsen MA, Fievet N, Massougbodji A, Luty AJF, Deloron P. Protective Antibodies against Placental Malaria and Poor Outcomes during Pregnancy, Benin. Emerg Infect Dis 2016; 21:813-23. [PMID: 25898123 PMCID: PMC4412227 DOI: 10.3201/eid2105.141626] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Immunity requires a vaccine that inhibits binding of infected erythrocytes to chondroitin sulfate. Placental malaria is caused by Plasmodium falciparum–infected erythrocytes that bind to placental tissue. Binding is mediated by VAR2CSA, a parasite antigen coded by the var gene, which interacts with chondroitin sulfate A (CSA). Consequences include maternal anemia and fetal growth retardation. Antibody-mediated immunity to placental malaria is acquired during successive pregnancies, but the target of VAR2CSA-specific protective antibodies is unclear. We assessed VAR2CSA-specific antibodies in pregnant women and analyzed their relationships with protection against placental infection, preterm birth, and low birthweight. Antibody responses to the N-terminal region of VAR2CSA during early pregnancy were associated with reduced risks for infections and low birthweight. Among women infected during pregnancy, an increase in CSA binding inhibition was associated with reduced risks for placental infection, preterm birth, and low birthweight. These data suggest that antibodies against VAR2CSA N-terminal region mediate immunity to placental malaria and associated outcomes. Our results validate current vaccine development efforts with VAR2CSA N-terminal constructs.
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MESH Headings
- Adult
- Antibodies, Protozoan/blood
- Antibodies, Protozoan/immunology
- Antibody Specificity/immunology
- Antigens, Protozoan/immunology
- Benin/epidemiology
- Erythrocytes/immunology
- Erythrocytes/parasitology
- Female
- Follow-Up Studies
- Humans
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Infant
- Infant, Newborn
- Malaria/epidemiology
- Malaria/immunology
- Malaria/parasitology
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Patient Outcome Assessment
- Placenta/parasitology
- Plasmodium falciparum/immunology
- Pregnancy
- Pregnancy Complications, Parasitic/epidemiology
- Pregnancy Complications, Parasitic/immunology
- Pregnancy Complications, Parasitic/parasitology
- Pregnancy Outcome
- Protein Binding
- Risk Factors
- Young Adult
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14
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Thrane S, Janitzek CM, Agerbæk MØ, Ditlev SB, Resende M, Nielsen MA, Theander TG, Salanti A, Sander AF. A Novel Virus-Like Particle Based Vaccine Platform Displaying the Placental Malaria Antigen VAR2CSA. PLoS One 2015; 10:e0143071. [PMID: 26599509 PMCID: PMC4657905 DOI: 10.1371/journal.pone.0143071] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 10/30/2015] [Indexed: 11/24/2022] Open
Abstract
Placental malaria caused by Plasmodium falciparum is a major cause of mortality and severe morbidity. Clinical testing of a soluble protein-based vaccine containing the parasite ligand, VAR2CSA, has been initiated. VAR2CSA binds to the human receptor chondroitin sulphate A (CSA) and is responsible for sequestration of Plasmodium falciparum infected erythrocytes in the placenta. It is imperative that a vaccine against malaria in pregnancy, if administered to women before they become pregnant, can induce a strong and long lasting immune response. While most soluble protein-based vaccines have failed during clinical testing, virus-like particle (VLP) based vaccines (e.g., the licensed human papillomavirus vaccines) have demonstrated high efficacy, suggesting that the spatial assembly of the vaccine antigen is a critical parameter for inducing an optimal long-lasting protective immune response. We have developed a VLP vaccine display platform by identifying regions of the HPV16 L1 coat protein where a biotin acceptor site (AviTagTM) can be inserted without compromising VLP-assembly. Subsequent biotinylation of Avi-L1 VLPs allow us to anchor monovalent streptavidin (mSA)-fused proteins to the biotin, thereby obtaining a dense and repetitive VLP-display of the vaccine antigen. The mSA-VAR2CSA antigen was delivered on the Avi-L1 VLP platform and tested in C57BL/6 mice in comparison to two soluble protein-based vaccines consisting of naked VAR2CSA and mSA-VAR2CSA. The mSA-VAR2CSA Avi-L1 VLP and soluble mSA-VAR2CSA vaccines induced higher antibody titers than the soluble naked VAR2CSA vaccine after three immunizations. The VAR2CSA Avi-L1 VLP vaccine induced statistically significantly higher endpoint titres compared to the soluble mSA-VAR2CSA vaccine, after 1st and 2nd immunization; however, this difference was not statistically significant after 3rd immunization. Importantly, the VLP-VAR2CSA induced antibodies were functional in inhibiting the binding of parasites to CSA. This study demonstrates that the described Avi-L1 VLP-platform may serve as a versatile system for facilitating optimal VLP-display of large and complex vaccine antigens.
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Affiliation(s)
- Susan Thrane
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Christoph M. Janitzek
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Mette Ø. Agerbæk
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Sisse B. Ditlev
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Mafalda Resende
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Morten A. Nielsen
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Thor G. Theander
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Adam F. Sander
- Centre for Medical Parasitology at the Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital, Copenhagen, Denmark
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15
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Nielsen MA, Resende M, de Jongh WA, Ditlev SB, Mordmüller B, Houard S, Ndam NT, Agerbæk MØ, Hamborg M, Massougbodji A, Issifou S, Strøbæk A, Poulsen L, Leroy O, Kremsner PG, Chippaux JP, Luty AJF, Deloron P, Theander TG, Dyring C, Salanti A. The Influence of Sub-Unit Composition and Expression System on the Functional Antibody Response in the Development of a VAR2CSA Based Plasmodium falciparum Placental Malaria Vaccine. PLoS One 2015; 10:e0135406. [PMID: 26327283 PMCID: PMC4556615 DOI: 10.1371/journal.pone.0135406] [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: 04/15/2015] [Accepted: 07/21/2015] [Indexed: 11/19/2022] Open
Abstract
The disease caused by Plasmodium falciparum (Pf) involves different clinical manifestations that, cumulatively, kill hundreds of thousands every year. Placental malaria (PM) is one such manifestation in which Pf infected erythrocytes (IE) bind to chondroitin sulphate A (CSA) through expression of VAR2CSA, a parasite-derived antigen. Protection against PM is mediated by antibodies that inhibit binding of IE in the placental intervillous space. VAR2CSA is a large antigen incompatible with large scale recombinant protein expression. Vaccines based on sub-units encompassing the functionally constrained receptor-binding domains may, theoretically, circumvent polymorphisms, reduce the risk of escape-mutants and induce cross-reactive antibodies. However, the sub-unit composition and small differences in the borders, may lead to exposure of novel immuno-dominant antibody epitopes that lead to non-functional antibodies, and furthermore influence the folding, stability and yield of expression. Candidate antigens from the pre-clinical development expressed in High-Five insect cells using the baculovirus expression vector system were transitioned into the Drosophila Schneider-2 cell (S2) expression-system compliant with clinical development. The functional capacity of antibodies against antigens expressed in High-Five cells or in S2 cells was equivalent. This enabled an extensive down-selection of S2 insect cell-expressed antigens primarily encompassing the minimal CSA-binding region of VAR2CSA. In general, we found differential potency of inhibitory antibodies against antigens with the same borders but of different var2csa sequences. Likewise, we found that subtle size differences in antigens of the same sequence gave varying levels of inhibitory antibodies. The study shows that induction of a functional response against recombinant subunits of the VAR2CSA antigen is unpredictable, demonstrating the need for large-scale screening in order to identify antigens that induce a broadly strain-transcending antibody response.
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Affiliation(s)
- Morten A. Nielsen
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * E-mail:
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | | | - Sisse B. Ditlev
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Benjamin Mordmüller
- Eberhard Karls Universität Tübingen, Institut für Tropenmedizin, Tübingen, Germany, and Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | - Sophie Houard
- European Vaccine Initiative, Universitäts Klinikum Heidelberg, Heidelberg, Germany
| | - Nicaise Tuikue Ndam
- Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
| | - Mette Ø. Agerbæk
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Mette Hamborg
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Achille Massougbodji
- Faculté des Sciences de la Santé de l’Université d’Abomey-Calavi, Centre d’étude et de recherche sur le paludisme associé à la grossesse et à l’enfance, Cotonou, Bénin
| | - Saddou Issifou
- Faculté des Sciences de la Santé de l’Université d’Abomey-Calavi, Centre d’étude et de recherche sur le paludisme associé à la grossesse et à l’enfance, Cotonou, Bénin
| | - Anette Strøbæk
- ExpreSion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark
| | - Lars Poulsen
- ExpreSion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark
| | - Odile Leroy
- European Vaccine Initiative, Universitäts Klinikum Heidelberg, Heidelberg, Germany
| | - Peter G. Kremsner
- Eberhard Karls Universität Tübingen, Institut für Tropenmedizin, Tübingen, Germany, and Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
| | - Jean-Philippe Chippaux
- Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- Faculté des Sciences de la Santé de l’Université d’Abomey-Calavi, Centre d’étude et de recherche sur le paludisme associé à la grossesse et à l’enfance, Cotonou, Bénin
| | - Adrian J. F. Luty
- Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
- Faculté des Sciences de la Santé de l’Université d’Abomey-Calavi, Centre d’étude et de recherche sur le paludisme associé à la grossesse et à l’enfance, Cotonou, Bénin
| | - Philippe Deloron
- Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France
- PRES Sorbonne Paris Cité, Université Paris Descartes, Paris, France
| | - Thor G. Theander
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Charlotte Dyring
- ExpreSion Biotechnologies, SCION-DTU Science Park, Hørsholm, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at Department of Immunology and Microbiology, Faculty of Health and Medical Science, University of Copenhagen, and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
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Multiple Plasmodium falciparum Erythrocyte Membrane Protein 1 Variants per Genome Can Bind IgM via Its Fc Fragment Fcμ. Infect Immun 2015. [PMID: 26216422 PMCID: PMC4567627 DOI: 10.1128/iai.00337-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) adhesive proteins expressed on the surfaces of infected erythrocytes (IEs) are of key importance in the pathogenesis of P. falciparum malaria. Several structurally and functionally defined PfEMP1 types have been associated with severe clinical manifestations, such as cerebral malaria in children and placental malaria in pregnant women. PfEMP1 that can bind the Fc part of IgM (Fcμ) characterizes one such type, although the functional significance of this IgM binding to PfEMP1 remains unclear. In this study, we report the identification and functional analysis of five IgM-binding PfEMP1 proteins encoded by P. falciparum NF54. In addition to the VAR2CSA-type PFL0030c protein, already known to bind Fcμ and to mediate chondroitin sulfate A (CSA)-specific adhesion of IEs in the placenta, we found four PfEMP1 proteins not previously known to bind IgM this way. Although they all contained Duffy binding-like ε (DBLε) domains similar to those in VAR2CSA-type PfEMP1, they did not mediate IE adhesion to CSA, and IgM binding did not shield IEs from phagocytosis of IgG-opsonized IEs. In this way, these new IgM-binding PfEMP1 proteins resemble the rosette-mediating and IgM-binding PfEMP1 HB3VAR06, but none of them mediated formation of rosettes. We could map the capacity for Fc-specific IgM binding to DBLε domains near the C terminus for three of the four PfEMP1 proteins tested. Our study provides new evidence regarding Fc-dependent binding of IgM to PfEMP1, which appears to be a common and multifunctional phenotype.
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Hempel C, Boisen IM, Efunshile A, Kurtzhals JAL, Staalsø T. An automated method for determining the cytoadhesion of Plasmodium falciparum-infected erythrocytes to immobilized cells. Malar J 2015; 14:112. [PMID: 25881267 PMCID: PMC4391601 DOI: 10.1186/s12936-015-0632-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/02/2015] [Indexed: 11/29/2022] Open
Abstract
Background Plasmodium falciparum exports antigens to the surface of infected erythrocytes causing cytoadhesion to the host vasculature. This is central in malaria pathogenesis but in vitro studies of cytoadhesion rely mainly on manual counting methods. The current study aimed at developing an automated high-throughput method for this purpose utilizing the pseudoperoxidase activity of intra-erythrocytic haemoglobin. Methods Chinese hamster ovary (CHO) cells were grown to confluence in chamber slides and microtiter plates. Cytoadhesion of co-cultured P. falciparum, selected for binding to CHO cells, was quantified by microscopy of Giemsa-stained chamber slides. In the automated assay, binding was quantified spectrophotometrically in microtiter plates after cell lysis using tetramethylbenzidine as peroxidase-catalysed substrate. The relevance of the method for binding studies was assessed using: i) binding of P. falciparum-infected erythrocytes to CHO cells over-expressing chondroitin sulfate A and ii) CHO cells transfected with CD36. Binding of infected erythrocytes including field isolates to primary endothelial cells was also performed. Data was analysed using linear regression and Bland-Altman plots. Results The manual and automated quantification showed strong, positive correlation (r2 = 0.959, p <0.001) and with similar detection limit and precision. The automated assay showed the expected dose-dependent reduction in binding to CHO cells when blocking with soluble chondroitin sulfate A or anti-CD36 antibody. Quantification of binding to endothelial cells showed clear distinction between selected vs. non-selected parasite lines. Importantly, the assay was sufficiently sensitive to detect adhesion of field isolates to endothelial cells. Conclusions The assay is simple and in a reproducible manner quantifies erythrocyte adhesion to several types of immobilized cells.
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Affiliation(s)
- Casper Hempel
- Centre for Medical Parasitology at Department of Clinical Microbiology, Copenhagen University Hospital Department Clinical Microbiology, 7602, Ole Maaløesvej 26, 2200, Copenhagen N, Denmark.
| | - Ida M Boisen
- Centre for Medical Parasitology at Department of Clinical Microbiology, Copenhagen University Hospital Department Clinical Microbiology, 7602, Ole Maaløesvej 26, 2200, Copenhagen N, Denmark. .,Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
| | - Akinwale Efunshile
- Institute of Medical Microbiology and Infectious Disease Epidemiology, Medical Faculty, University of Leipzig, Leipzig, Germany. .,Department of Medical Microbiology, Federal Teaching Hospital/Ebonyi State University, Abakaliki, Nigeria.
| | - Jørgen A L Kurtzhals
- Centre for Medical Parasitology at Department of Clinical Microbiology, Copenhagen University Hospital Department Clinical Microbiology, 7602, Ole Maaløesvej 26, 2200, Copenhagen N, Denmark. .,Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
| | - Trine Staalsø
- Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
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18
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Nielsen MA, Salanti A. High-Throughput Testing of Antibody-Dependent Binding Inhibition of Placental Malaria Parasites. Methods Mol Biol 2015; 1325:241-53. [PMID: 26450394 DOI: 10.1007/978-1-4939-2815-6_20] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The particular virulence of Plasmodium falciparum manifests in diverse severe malaria syndromes as cerebral malaria, severe anemia and placental malaria. The cause of both the severity and the diversity of infection outcome, is the ability of the infected erythrocyte (IE) to bind a range of different human receptors through Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) on the surface of the infected cell. As the var genes encoding the large PfEMP1 antigens are extensively polymorphic, vaccine development strategies are focused on targeting the functional binding epitopes. This involves identification of recombinant fragments of PfEMP1s that induce antibodies, which hinder the adhesion of the IE to a given receptor or tissue. Different assays to measure the blocking of adhesion have been described in the literature, each with different advantages. This chapter describes a high-throughput assay used in the preclinical and clinical development of a VAR2CSA based vaccine against placental malaria.
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Affiliation(s)
- Morten A Nielsen
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, CSS Building 22/23, Øster Farimagsgade 5, 2099, Copenhagen K, 1014, Denmark.
| | - Ali Salanti
- Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, CSS Building 22/23, Øster Farimagsgade 5, 2099, Copenhagen K, 1014, Denmark.
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19
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Functional antibodies against VAR2CSA in nonpregnant populations from colombia exposed to Plasmodium falciparum and Plasmodium vivax. Infect Immun 2014; 82:2565-73. [PMID: 24686068 DOI: 10.1128/iai.01594-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In pregnancy, parity-dependent immunity is observed in response to placental infection with Plasmodium falciparum. Antibodies recognize the surface antigen, VAR2CSA, expressed on infected red blood cells and inhibit cytoadherence to the placental tissue. In most settings of malaria endemicity, antibodies against VAR2CSA are predominantly observed in multigravid women and infrequently in men, children, and nulligravid women. However, in Colombia, we detected antibodies against multiple constructs of VAR2CSA among men and children with acute P. falciparum and Plasmodium vivax infection. The majority of men and children (>60%) had high levels of IgGs against three recombinant domains of VAR2CSA: DBL5ε, DBL3X, and ID1-ID2. Surprisingly, these antibodies were observed only in pregnant women, men, and children exposed either to P. falciparum or to P. vivax. Moreover, the anti-VAR2CSA antibodies are of high avidity and efficiently inhibit adherence of infected red blood cells to chondroitin sulfate A in vitro, suggesting that they are specific and functional. These unexpected results suggest that there may be genotypic or phenotypic differences in the parasites of this region or in the host response to either P. falciparum or P. vivax infection outside pregnancy. These findings may hold significant clinical relevance to the pathophysiology and outcome of malaria infections in this region.
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20
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Induction of pro-inflammatory response of the placental trophoblast by Plasmodium falciparum infected erythrocytes and TNF. Malar J 2013; 12:421. [PMID: 24237643 PMCID: PMC3834101 DOI: 10.1186/1475-2875-12-421] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 10/23/2013] [Indexed: 01/18/2023] Open
Abstract
Background Plasmodium falciparum placental malaria is characterized by the sequestration of infected erythrocytes (IEs) in the placental intervillous space via adherence to chondroitin sulphate A (CSA), production of inflammatory molecules, and leukocytes infiltration. Previous reports suggest that the syncytiotrophoblast (ST) immunologically responds to IEs contact. This study explores the inflammatory response induced in BeWo cells by adherence of IEs and TNFstimulation. Methods A non-syncitialized BeWo cells (trophoblast model) were used to evaluate its response to CSA-adherents IEs (FCB1csa, FCB2csa, FCR3csa, 3D7csa) and TNF stimulation. Expression of membrane ICAM-1 (mICAM-1) receptor in BeWo cells was quantified by flow cytometry and the IL-8, IL-6 and soluble ICAM-1 (sICAM-1) concentrations were quantified by enzyme-linked immunosorbentassay (ELISA) in BeWo stimulated supernatants. Results BeWo cells stimulated with TNF and CSA-adherents IEs of FCB1csa and 3D7csa (strains with higher adhesion) increase the expression of ICAM-1 on the surface of cells and the secretion of immune factors IL-8, IL-6 and sICAM-1. This inflammatory response appears to be related to the level of adherence of IEs because less adherent strains do not induce significant changes. Conclusions It was found that BeWo cells responds to CSA-IEs and to TNF favouring a placental pro-inflammatory environment, evidenced by increases in the expression of membrane mICAM-1 and release of soluble ICAM-1, as well as the IL-8 and IL-6 secretion. The expression of ICAM-1 in BeWo cells might be associated to an increase in leukocyte adhesion to the trophoblast barrier, promoting greater inflammation, while the sICAM-1 release could be a protection mechanism activated by trophoblastic cells, in order to regulate the local inflammatory response.
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21
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Doritchamou J, Bigey P, Nielsen MA, Gnidehou S, Ezinmegnon S, Burgain A, Massougbodji A, Deloron P, Salanti A, Ndam NT. Differential adhesion-inhibitory patterns of antibodies raised against two major variants of the NTS-DBL2X region of VAR2CSA. Vaccine 2013; 31:4516-22. [PMID: 23933341 DOI: 10.1016/j.vaccine.2013.07.072] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 07/19/2013] [Accepted: 07/29/2013] [Indexed: 11/18/2022]
Abstract
BACKGROUND VAR2CSA is a large polymorphic Plasmodium falciparum protein expressed on infected erythrocytes (IE) that allows their binding in the placenta, thus precipitating placental malaria (PM). The N-terminal part of VAR2CSA that contains the binding site to placental chondroitin sulfate A (CSA) is currently recognized as the most attractive region for vaccine development. An ultimate challenge is to define epitopes in this region that induce a broad cross-reactive adhesion inhibitory antibody response. METHODS Based on phylogenetic data that identified a dimorphic sequence motif in the VAR2CSA DBL2X, we raised antibodies against the NTS-DBL2X constructs containing one sequence or the other (3D7 and FCR3) and tested their functional properties on P. falciparum isolates from pregnant women and on laboratory-adapted strains. RESULTS The CSA binding inhibitory capacity of the antibodies induced varied from one parasite isolate to another (range, 10%–100%), but the combined analysis of individual activity highlighted a broader functionality that increased the total number of isolates inhibited. Interestingly, the differential inhibitory effect of the antibodies observed on field isolates resulted in significant inhibition of all field isolates tested, suggesting that optimal inhibitory spectrum on field isolates from pregnant women might be achieved with antibodies targeting limited variants of the N-terminal VAR2CSA. CONCLUSIONS Our findings indicate that the NTS-DBL2X region of VAR2CSA can elicit strain-transcending anti-adhesion antibodies and suggest that the combination of the two major variants used here could represent the basis for an effective bivalent VAR2CSA-based vaccine.
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Affiliation(s)
- Justin Doritchamou
- PRES Sorbonne Paris Cité, Faculté de Pharmacie, Université Paris Descartes, France; Institut de Recherche pour le Développement, UMR216 Mère et enfant face aux infections tropicales, Paris, France; Centre d'Etude et de Recherche sur le paludisme associé à la Grossesse et à l'Enfance, Université d'Abomey-Calavi, Cotonou, Benin
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22
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Doritchamou J, Bertin G, Moussiliou A, Bigey P, Viwami F, Ezinmegnon S, Fievet N, Massougbodji A, Deloron P, Tuikue Ndam N. First-trimester Plasmodium falciparum infections display a typical "placental" phenotype. J Infect Dis 2012; 206:1911-9. [PMID: 23045626 DOI: 10.1093/infdis/jis629] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Plasmodium falciparum-infected erythrocytes (IEs) adhere to host cell receptors, allowing parasites to sequester into deep vascular beds of various organs. This defining phenomenon of malaria pathogenesis is key to the severe clinical complications associated with cerebral and placental malaria. The principal ligand associated with the binding to chondroitin sulfate A (CSA) that allows placental sequestration of IEs is a P. falciparum erythrocyte membrane protein 1 (PfEMP1) family member encoded by the var2csa gene. METHODS Here, we investigated the transcription pattern of var genes by real-time polymerase chain reaction, the expression of VAR2CSA, protein by flow cytometry, and the CSA-binding ability of IEs collected at different stages of pregnancy using a static-based Petri dish assay. RESULTS Through comparison with the profiles of isolates from nonpregnant hosts, we report several lines of evidence showing that parasites infecting women during pregnancy preferentially express VAR2CSA protein, and that selection for the capacity to adhere to CSA via VAR2CSA expression occurs early in pregnancy. CONCLUSIONS Our data suggest that the placental tropism of P. falciparum is already established in the first trimester of pregnancy, with consequent implications for the development of the pathology associated with placental malaria.
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Affiliation(s)
- Justin Doritchamou
- PRES Sorbonne Paris Cité, Faculté de Pharmacie, Université Paris Descartes, Paris, France
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23
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Lee SM, Romero R, Lee YJ, Park IS, Park CW, Yoon BH. Systemic inflammatory stimulation by microparticles derived from hypoxic trophoblast as a model for inflammatory response in preeclampsia. Am J Obstet Gynecol 2012; 207:337.e1-8. [PMID: 23021701 DOI: 10.1016/j.ajog.2012.06.047] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 05/03/2012] [Accepted: 06/25/2012] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether trophoblast-derived microparticles can induce different inflammatory responses of the peripheral blood mononuclear cells depending upon the state of trophoblast when the microparticles are generated. STUDY DESIGN A trophoblast-derived cell line (ATCC no. CRL-1584) was cultured under normal or hypoxic conditions. Microparticles were isolated from the cell culture supernatants (microparticles from normal trophoblast; microparticles from hypoxic trophoblast). Peripheral blood mononuclear cells were cultured alone or cocultured with either microparticles from normal trophoblast or microparticles from hypoxic trophoblast. RESULTS After 48 hours, the peripheral blood mononuclear cells cocultured with microparticles from normal trophoblast released higher concentrations of interleukin-6 than peripheral blood mononuclear cells cultured alone. The peripheral blood mononuclear cells cocultured with microparticles from hypoxic trophoblast showed higher concentration of interleukin-6 and tumor necrosis factor alpha than peripheral blood mononuclear cells cocultured with microparticles from normal trophoblast, after 24 hours and 48 hours. CONCLUSION More intense and rapid inflammatory response of peripheral blood mononuclear cells was observed with microparticles from hypoxic trophoblast than with microparticles from normal trophoblast. This difference might explain the exaggerated systemic inflammatory response as a result of placental hypoxia in preeclampsia.
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Affiliation(s)
- Seung Mi Lee
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea
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Quadt KA, Barfod L, Andersen D, Bruun J, Gyan B, Hassenkam T, Ofori MF, Hviid L. The density of knobs on Plasmodium falciparum-infected erythrocytes depends on developmental age and varies among isolates. PLoS One 2012; 7:e45658. [PMID: 23029166 PMCID: PMC3447797 DOI: 10.1371/journal.pone.0045658] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 08/20/2012] [Indexed: 12/12/2022] Open
Abstract
Background The virulence of Plasmodium falciparum malaria is related to the parasite’s ability to evade host immunity through clonal antigenic variation and tissue-specific adhesion of infected erythrocytes (IEs). The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family expressed on dome-shaped protrusions called knobs on the IE surface is central to both. Differences in receptor specificity and affinity of expressed PfEMP1 are important for IE adhesiveness, but it is not known whether differences in the number and size of the knobs on which the PfEMP1 proteins are expressed also play a role. Therefore, the aim of this study was to provide detailed information on isolate- and time-dependent differences in knob size and density. Methodology/Principal Findings We used atomic force microscopy to characterize knobs on the surface of P. falciparum-infected erythrocytes. Fourteen ex vivo isolates from Ghanaian children with malaria and 10 P. falciparum isolates selected in vitro for expression of a particular PfEMP1 protein (VAR2CSA) were examined. Knob density increased from ∼20 h to ∼35 h post-invasion, with significant variation among isolates. The knob density ex vivo, which was about five-fold higher than following long-term in vitro culture, started to decline within a few months of culture. Although knob diameter and height varied among isolates, we did not observe significant time-dependent variation in these dimensions. Conclusions/Significance The density of knobs on the P. falciparum-IE surface depends on time since invasion, but is also determined by the infecting isolate in a time-independent manner. This is the first study to quantitatively evaluate knob densities and dimensions on different P. falciparum isolates, to examine ex vivo isolates from humans, and to compare ex vivo and long-term in vitro-cultured isolates. Our findings contribute to the understanding of the interaction between P. falciparum parasites and the infected host.
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Affiliation(s)
- Katharina A. Quadt
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Lea Barfod
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Daniel Andersen
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Jonas Bruun
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ben Gyan
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Tue Hassenkam
- Nano-Science Centre, Department of Chemistry, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Michael F. Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Lars Hviid
- Centre for Medical Parasitology at i, Faculty of Health and Medical Sciences, University of Copenhagen and at Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * E-mail:
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Ku MJ, Dossin FDM, Hansen MAE, Genovesio A, Ayong L, Freitas-Junior LH. An image-based drug susceptibility assay targeting the placental sequestration of Plasmodium falciparum-infected erythrocytes. PLoS One 2012; 7:e41765. [PMID: 22952585 PMCID: PMC3430655 DOI: 10.1371/journal.pone.0041765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 06/27/2012] [Indexed: 11/19/2022] Open
Abstract
Placental malaria is a significant cause of all malaria-related deaths globally for which no drugs have been developed to specifically disrupt its pathogenesis. To facilitate the discovery of antimalarial drugs targeting the cytoadherence process of Plasmodium-infected erythrocytes in the placenta microvasculature, we have developed an automated image-based assay for high-throughput screening for potent cytoadherence inhibitors in vitro. Parasitized erythrocytes were drug-treated for 24 h and then allowed to adhere on a monolayer of placental BeWo cells prior to red blood cell staining with glycophorin A antibodies. Upon image-acquisition, drug effects were quantified as the proportion of treated parasitized erythrocytes to BeWo cells compared to the binding of untreated iRBCs. We confirmed the reliability of this new assay by comparing the binding ratios of CSA- and CD36-panned parasites on the placental BeWo cells, and by quantifying the effects of chondroitin sulfate A, brefeldin A, and artemisinin on the binding. By simultaneously examining the drug effects on parasite viability, we could discriminate between cytoadherence-specific inhibitors and other schizonticidal compounds. Taken together, our data establish that the developed assay is highly suitable for drug studies targeting placental malaria, and will facilitate the discovery and rapid development of new therapies against malaria.
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Affiliation(s)
- Min-Je Ku
- Center for Neglected Diseases Drug Discovery (CND3), Institut Pasteur Korea, Seongnam-si, Gyeonggi-do, South Korea
| | - Fernando de M. Dossin
- Center for Neglected Diseases Drug Discovery (CND3), Institut Pasteur Korea, Seongnam-si, Gyeonggi-do, South Korea
| | - Michael A. E. Hansen
- Center for Core Technologies-Image Mining, Institut Pasteur Korea, Seongnam-si, Gyeonggi-do, South Korea
| | - Auguste Genovesio
- Center for Core Technologies-Image Mining, Institut Pasteur Korea, Seongnam-si, Gyeonggi-do, South Korea
| | - Lawrence Ayong
- Center for Neglected Diseases Drug Discovery (CND3), Institut Pasteur Korea, Seongnam-si, Gyeonggi-do, South Korea
| | - Lucio H. Freitas-Junior
- Center for Neglected Diseases Drug Discovery (CND3), Institut Pasteur Korea, Seongnam-si, Gyeonggi-do, South Korea
- * E-mail:
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Bordbar B, Tuikue-Ndam N, Bigey P, Doritchamou J, Scherman D, Deloron P. Identification of Id1-DBL2X of VAR2CSA as a key domain inducing highly inhibitory and cross-reactive antibodies. Vaccine 2012; 30:1343-8. [PMID: 22226864 DOI: 10.1016/j.vaccine.2011.12.065] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 12/09/2011] [Accepted: 12/13/2011] [Indexed: 11/29/2022]
Abstract
PURPOSE OF THE RESEARCH VAR2CSA is considered as the main target of protective immunity against pregnancy-associated malaria. VAR2CSA high molecular weight complicates scaling up production of VAR2CSA recombinant protein for large-scale vaccination programmes. We previously demonstrated that antibodies induced by NTS-DBL1X-Id1-DBL2X efficiently block parasite binding to CSA in a similar manner to antibodies induced by the full-length extracellular part of VAR2CSA. In order to identifying the shortest fragment of VAR2CSA carrying major protective epitopes able to elicit inhibitory antibodies, we performed a refined antigenic mapping of NTS-DBL1X-Id1-DBL2X through a DNA vaccination technique. PRINCIPAL RESULTS Five single or double domains constructs encoding NTS-DBL1X, NTS-DBL1X-Id1, Id1, Id1-DBL2X and DBL2X were made and used to immunize mice. The NTS-DBL1X, NTS-DBL1X-Id1, and Id1-DBL2X fragments all raised high titer immune response, as measured by ELISA. The DBL2X fragment raised a weaker antibody titer, and the Id1 construct failed to elicit antibody. Sera from mice immunized with NTS-DBL1X or DBL2X constructs failed to block infected erythrocytes binding to CSA, whereas sera from mice immunized with NTS-DBL1X-Id1 showed partial inhibitory activity, and the Id1-DBL2X fragment elicited antisera that totally abrogated infected erythrocytes adhesion to CSA. IgG purified from Id1-DBL2X antisera showed a similar inhibitory profile than Id1-DBL2X antisera. Anti-FCR3 anti-Id1-DBL2X antibodies also efficiently block the adhesion of erythrocytes infected by the HB3 parasite line to CSA. Id1-DBL2X antisera recognized the surface of field isolates from pregnant women, and inhibited CSA-binding of all 8 isolates tested, although to a variable level. MAJOR CONCLUSIONS We raised high-titer antibodies against several parts of the protein, and identified Id1-DBL2X as the minimal VAR2CSA fragment inducing antibodies with CSA-binding inhibitory efficiency in the same range as the full-length extracellular part of VAR2CSA.
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Affiliation(s)
- Bita Bordbar
- Université Paris Descartes, Sorbonne Paris Cité, 75006 Paris, France
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27
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Bordbar B, Gnidehou S, Ndam NT, Doritchamou J, Moussiliou A, Quiviger M, Deloron P, Scherman D, Bigey P. Electroporation-mediated genetic vaccination for antigen mapping: application to Plasmodium falciparum VAR2CSA protein. Bioelectrochemistry 2011; 87:132-7. [PMID: 22265101 DOI: 10.1016/j.bioelechem.2011.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Revised: 11/22/2011] [Accepted: 12/21/2011] [Indexed: 01/28/2023]
Abstract
Genetic vaccination, consisting in delivering a genetically engineered plasmid DNA by a non-viral vector or technique into a tissue, is currently of great interest. New delivery technique including DNA transfer by electroporation recently greatly improved the potency of this concept. Because it avoids the step of producing a recombinant protein, it is particularly of use in studying the immunogenic properties of large proteins. Here we describe the use of electroporation mediated DNA immunization to identify important protective epitopes from the large VAR2CSA protein from Plasmodium falciparum implicated in the pathology of placental malaria. Immunizing mice and rabbit with DNA plasmids encoding different fragments of VAR2CSA leads to high titer antisera. Moreover an N-terminal region of the protein was found to induce protective functional antibodies.
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Affiliation(s)
- Bita Bordbar
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
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Pinto VV, Salanti A, Joergensen LM, Dahlbäck M, Resende M, Ditlev SB, Agger EM, Arnot DE, Theander TG, Nielsen MA. The effect of adjuvants on the immune response induced by a DBL4ɛ-ID4 VAR2CSA based Plasmodium falciparum vaccine against placental malaria. Vaccine 2011; 30:572-9. [PMID: 22122859 DOI: 10.1016/j.vaccine.2011.11.068] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 10/15/2011] [Accepted: 11/16/2011] [Indexed: 10/15/2022]
Abstract
A vaccine protecting women against placental malaria could be based on the sub-domains of the VAR2CSA antigen, since antibodies against the DBL4ɛ-ID4 subunit of the VAR2CSA protein can inhibit parasite binding to the placental ligand chondroitin sulphate A (CSA). Here we tested the ability of DBL4ɛ-ID4 to induce binding-inhibitory antibodies when formulated with adjuvants approved for human use. We have characterized the immune response of DBL4ɛ-ID4 in combination with Freund's complete and incomplete adjuvant and with three adjuvants currently being used in clinical trials: Montanide(®) ISA 720, Alhydrogel(®) and CAF01. Antibodies induced against DBL4ɛ-ID4 in combination with these adjuvants inhibited parasite binding to CSA from 82% to 99%. Although, different epitope recognition patterns were obtained for the different formulations, all adjuvant combinations induced strong Th1 and Th2 type responses, resulting in IgG with similar binding strength, with to the DBL4ɛ-ID4 antigen. These results demonstrate that the DBL4ɛ-ID4 antigen is highly immunogenic and that binding inhibitory antibodies are induced when formulated with any of the tested adjuvants.
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Affiliation(s)
- V V Pinto
- Centre for Medical Parasitology, Department of International Health, University of Copenhagen, CSS, Øster Farimagsgade 5 A, DK-1014 Copenhagen K, Denmark.
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29
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Bigey P, Gnidehou S, Doritchamou J, Quiviger M, Viwami F, Couturier A, Salanti A, Nielsen MA, Scherman D, Deloron P, Tuikue Ndam N. The NTS-DBL2X region of VAR2CSA induces cross-reactive antibodies that inhibit adhesion of several Plasmodium falciparum isolates to chondroitin sulfate A. J Infect Dis 2011; 204:1125-33. [PMID: 21881129 DOI: 10.1093/infdis/jir499] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Binding to chondroitin sulfate A by VAR2CSA, a parasite protein expressed on infected erythrocytes, allows placental sequestration of Plasmodium falciparum-infected erythrocytes. This leads to severe consequences such as maternal anemia, stillbirths, and intrauterine growth retardation. The latter has been clearly associated to increased morbidity and mortality of the infants. Acquired anti-VAR2CSA antibodies have been associated with improved pregnancy outcomes, suggesting a vaccine could prevent the syndrome. However, identifying functionally important regions in the large VAR2CSA protein is difficult. METHODS Using genetic immunization, we raised polyclonal antisera against overlapping segments of VAR2CSA in mice and rabbits. The adhesion-inhibition capacities of induced antisera and of specific antibodies purified from plasma of malaria-exposed pregnant women were assessed on laboratory-adapted parasite lines and field isolates expressing VAR2CSA. Competition enzyme-linked immunosorbent assay (ELISA) was employed to analyze functional resemblance between antibodies induced in animals and those naturally acquired by immune multigravidae. RESULTS Antibodies targeting the N-terminal sequence (NTS) up to DBL2X (NTS-DBL2X) efficiently blocked parasite adhesion to chondroitin sulfate A in a manner similar to that of antibodies raised against the entire VAR2CSA extracellular domain. Interestingly, naturally acquired antibodies and those induced by vaccination against NTS-DBL2X target overlapping strain-transcendent anti-adhesion epitopes. CONCLUSIONS This study highlights an important step achieved toward development of a protective vaccine against placental malaria.
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Affiliation(s)
- Pascal Bigey
- Unité de Pharmacologie Chimique et Génétique, Université Paris Descartes, ENSCP Chimie ParisTech, CNRS UMR8151, Inserm U 1022, France
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Evasion of immunity to Plasmodium falciparum malaria by IgM masking of protective IgG epitopes in infected erythrocyte surface-exposed PfEMP1. Proc Natl Acad Sci U S A 2011; 108:12485-90. [PMID: 21746929 DOI: 10.1073/pnas.1103708108] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum malaria is a major cause of mortality and severe morbidity. Its virulence is related to the parasite's ability to evade host immunity through clonal antigenic variation and tissue-specific adhesion of infected erythrocytes (IEs). The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family is central to both. Here, we present evidence of a P. falciparum evasion mechanism not previously documented: the masking of PfEMP1-specific IgG epitopes by nonspecific IgM. Nonspecific IgM binding to erythrocytes infected by parasites expressing the PfEMP1 protein VAR2CSA (involved in placental malaria pathogenesis and protective immunity) blocked subsequent specific binding of human monoclonal IgG to the Duffy binding-like (DBL) domains DBL3X and DBL5ε of this PfEMP1 variant. Strikingly, a VAR2CSA-specific monoclonal antibody that binds outside these domains and can inhibit IE adhesion to the specific VAR2CSA receptor chondroitin sulfate A was unaffected. Nonspecific IgM binding protected the parasites from FcγR-dependent phagocytosis of VAR2CSA(+) IEs, but it did not affect IE adhesion to chondroitin sulfate A or lead to C1q deposition on IEs. Taken together, our results indicate that the VAR2CSA affinity for nonspecific IgM has evolved to allow placenta-sequestering P. falciparum to evade acquired protective immunity without compromising VAR2CSA function or increasing IE susceptibility to complement-mediated lysis. Furthermore, functionally important PfEMP1 epitopes not prone to IgM masking are likely to be particularly important targets of acquired protective immunity to P. falciparum malaria.
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Pinto VV, Ditlev SB, Jensen KE, Resende M, Dahlbäck M, Andersen G, Andersen P, Theander TG, Salanti A, Nielsen MA. Differential induction of functional IgG using the Plasmodium falciparum placental malaria vaccine candidate VAR2CSA. PLoS One 2011; 6:e17942. [PMID: 21464946 PMCID: PMC3064590 DOI: 10.1371/journal.pone.0017942] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 02/15/2011] [Indexed: 11/18/2022] Open
Abstract
Background In Plasmodium falciparum malaria endemic areas placental malaria (PM) is an important complication of malaria. The recurrence of malaria in primigravidae women irrespective of acquired protection during childhood is caused by the interaction between the parasite-expressed VAR2CSA antigen and chondroitin sulfate A (CSA) in the placental intervillous space and lack of protective antibodies. PM impairs fetal development mainly by excessive inflammation processes. After infections during pregnancy women acquire immunity to PM conferred by antibodies against VAR2CSA. Ideally, a vaccine against PM will induce antibody-mediated immune responses that block the adhesion of infected erythrocytes (IE) in the placenta. Principal Findings We have previously shown that antibodies raised in rat against individual domains of VAR2CSA can block IE binding to CSA. In this study we have immunized mice, rats and rabbits with each individual domain and the full-length protein corresponding to the FCR3 VAR2CSA variant. We found there is an inherently higher immunogenicity of C-terminal domains compared to N-terminally located domains. This was irrespective of whether antibodies were induced against single domains or the full-length protein. Species-specific antibody responses were also found, these were mainly directed against single domains and not the full-length VAR2CSA protein. Conclusions/Significance Binding inhibitory antibodies appeared to be against conformational B-cell epitopes. Non-binding inhibitory antibodies reacted highly against the C-terminal end of the VAR2CSA molecule especially the highly polymorphic DBL6ε domain. Differential species-specific induction of antibody responses may allow for more direct analysis of functional versus non-functional B-cell epitopes.
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Affiliation(s)
- Vera V. Pinto
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Sisse B. Ditlev
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Kamilla E. Jensen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Mafalda Resende
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Madeleine Dahlbäck
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Gorm Andersen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Pernille Andersen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thor G. Theander
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Morten A. Nielsen
- Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * E-mail:
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Dahlbäck M, Jørgensen LM, Nielsen MA, Clausen TM, Ditlev SB, Resende M, Pinto VV, Arnot DE, Theander TG, Salanti A. The chondroitin sulfate A-binding site of the VAR2CSA protein involves multiple N-terminal domains. J Biol Chem 2011; 286:15908-17. [PMID: 21398524 PMCID: PMC3091200 DOI: 10.1074/jbc.m110.191510] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Malaria during pregnancy is a major health problem for African women. The disease is caused by Plasmodium falciparum malaria parasites, which accumulate in the placenta by adhering to chondroitin sulfate A (CSA). The interaction between infected erythrocytes and the placental receptor is mediated by a parasite expressed protein named VAR2CSA. A vaccine protecting pregnant women against placental malaria should induce antibodies inhibiting the interaction between VAR2CSA and CSA. Much effort has been put into defining the part of the 350 kDa VAR2CSA protein that is responsible for binding. It has been shown that full-length recombinant VAR2CSA binds specifically to CSA with high affinity, however to date no sub-fragment of VAR2CSA has been shown to interact with CSA with similar affinity or specificity. In this study, we used a biosensor technology to examine the binding properties of a panel of truncated VAR2CSA proteins. The experiments indicate that the core of the CSA-binding site is situated in three domains, DBL2X-CIDRPAM and a flanking domain, located in the N-terminal part of VAR2CSA. Furthermore, recombinant VAR2CSA subfragments containing this region elicit antibodies with high parasite adhesion blocking activity in animal immunization experiments.
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Affiliation(s)
- Madeleine Dahlbäck
- Department of International Health, Immunology, University of Copenhagen and the Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), Copenhagen K, Denmark.
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Barfod L, Dobrilovic T, Magistrado P, Khunrae P, Viwami F, Bruun J, Dahlbäck M, Bernasconi NL, Fried M, John D, Duffy PE, Salanti A, Lanzavecchia A, Lim CT, Ndam NT, Higgins MK, Hviid L. Chondroitin sulfate A-adhering Plasmodium falciparum-infected erythrocytes express functionally important antibody epitopes shared by multiple variants. THE JOURNAL OF IMMUNOLOGY 2010; 185:7553-61. [PMID: 21078904 DOI: 10.4049/jimmunol.1002390] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Acquired protection from Plasmodium falciparum placental malaria, a major cause of maternal, fetal, and infant morbidity, is mediated by IgG specific for the P. falciparum erythrocyte membrane protein 1 variant VAR2CSA. This protein enables adhesion of P. falciparum-infected erythrocytes to chondroitin sulfate A in the intervillous space. Although interclonal variation of the var2csa gene is lower than that among var genes in general, VAR2CSA-specific Abs appear to target mainly polymorphic epitopes. This has raised doubts about the feasibility of VAR2CSA-based vaccines. We used eight human monoclonal IgG Abs from affinity-matured memory B cells of P. falciparum-exposed women to study interclonal variation and functional importance of Ab epitopes among placental and peripheral parasites from East and West Africa. Most placental P. falciparum isolates were labeled by several mAbs, whereas peripheral isolates from children were essentially nonreactive. The mAb reactivity of peripheral isolates from pregnant women indicated that some were placental, whereas others had alternative sequestration foci. Most of the mAbs were comparable in their reactivity with bound infected erythrocytes (IEs) and recombinant VAR2CSA and interfered with IE and/or VAR2CSA binding to chondroitin sulfate A. Pair-wise mAb combinations were more inhibitory than single mAbs, and all of the mAbs together was the most efficient combination. Each mAb could opsonize IEs for phagocytosis, and a combination of the eight mAbs caused phagocytosis similar to that of plasma IgG-opsonized IEs. We conclude that functionally important Ab epitopes are shared by the majority of polymorphic VAR2CSA variants, which supports the feasibility of VAR2CSA-based vaccines against placental malaria.
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Affiliation(s)
- Lea Barfod
- Centre for Medical Parasitology, Department of International Health, Immunology, and Microbiology, University of Copenhagen, Denmark
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Gangnard S, Tuikue Ndam NG, Gnidehou S, Quiviger M, Juillerat A, Faure G, Baron B, Viwami F, Deloron P, Bentley GA. Functional and immunological characterization of the var2CSA-DBL5epsilon domain of a placental Plasmodium falciparum isolate. Mol Biochem Parasitol 2010; 173:115-22. [PMID: 20562018 DOI: 10.1016/j.molbiopara.2010.05.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 04/15/2010] [Accepted: 05/17/2010] [Indexed: 11/15/2022]
Abstract
Pregnancy-associated malaria (PAM) arises from sequestration of Plasmodium falciparum-parasitized erythrocytes (PE) in the placenta, leading to chronic symptoms in the expectant mother and serious consequences for fetal development. Placental sequestration has been linked to binding of chondroitin sulphate A (CSA) by the var2CSA variant of PfEMP1 expressed on the PE surface, and a substantial body of evidence shows that the immune response to var2CSA gives an effective protection against PAM. We have expressed the var2CSA-DBL5epsilon domain, derived from a placental isolate from Senegal, as soluble product in Escherichia coli and have shown using different criteria that the recombinant protein is obtained with the native conformation. Using surface plasmon resonance techniques, we have examined binding of DBL5epsilon to placental chondroitin sulphate proteoglycan and CSA; however, the recombinant protein also binds to other sulphated oligosaccharides, with higher affinity in some cases, indicating that the single domain lacks the specificity for CSA shown by the complete extra-cellular region of var2CSA and placental parasites. Recombinant DBL5epsilon was specifically recognized by sera from malaria-exposed Senegalese women in a parity-dependent manner but by sera not from children or males from the same endemic region. Conversely, DBL5epsilon induced antibodies in mice that recognized placental isolates from Benin but not isolates from children. The presence of universal epitopes thus supports DBL5epsilon as an interesting component of var2CSA to be considered for vaccine development.
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Affiliation(s)
- Stéphane Gangnard
- Institut Pasteur, Unité d'Immunologie Structurale, CNRS URA2185, Paris, France
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35
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Joergensen LM, Salanti A, Dobrilovic T, Barfod L, Hassenkam T, Theander TG, Hviid L, Arnot DE. The kinetics of antibody binding to Plasmodium falciparum VAR2CSA PfEMP1 antigen and modelling of PfEMP1 antigen packing on the membrane knobs. Malar J 2010; 9:100. [PMID: 20403153 PMCID: PMC2868858 DOI: 10.1186/1475-2875-9-100] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 04/19/2010] [Indexed: 11/25/2022] Open
Abstract
Background Infected humans make protective antibody responses to the PfEMP1 adhesion antigens exported by Plasmodium falciparum parasites to the erythrocyte membrane, but little is known about the kinetics of this antibody-receptor binding reaction or how the topology of PfEMP1 on the parasitized erythrocyte membrane influences antibody association with, and dissociation from, its antigenic target. Methods A Quartz Crystal Microbalance biosensor was used to measure the association and dissociation kinetics of VAR2CSA PfEMP1 binding to human monoclonal antibodies. Immuno-fluorescence microscopy was used to visualize antibody-mediated adhesion between the surfaces of live infected erythrocytes and atomic force microscopy was used to obtain higher resolution images of the membrane knobs on the infected erythrocyte to estimate knob surface areas and model VAR2CSA packing density on the knob. Results Kinetic analysis indicates that antibody dissociation from the VAR2CSA PfEMP1 antigen is extremely slow when there is a high avidity interaction. High avidity binding to PfEMP1 antigens on the surface of P. falciparum-infected erythrocytes in turn requires bivalent cross-linking of epitopes positioned within the distance that can be bridged by antibody. Calculations of the surface area of the knobs and the possible densities of PfEMP1 packing on the knobs indicate that high-avidity cross-linking antibody reactions are constrained by the architecture of the knobs and the large size of PfEMP1 molecules. Conclusions High avidity is required to achieve the strongest binding to VAR2CSA PfEMP1, but the structures that display PfEMP1 also tend to inhibit cross-linking between PfEMP1 antigens, by holding many binding epitopes at distances beyond the 15-18 nm sweep radius of an antibody. The large size of PfEMP1 will also constrain intra-knob cross-linking interactions. This analysis indicates that effective vaccines targeting the parasite's vulnerable adhesion receptors should primarily induce strongly adhering, high avidity antibodies whose association rate constant is less important than their dissociation rate constant.
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Affiliation(s)
- Lars M Joergensen
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital (Rigshospitalet), CSS Øster Farimagsgade 5, Building 22 & 23, Postbox 2099, 1014 Copenhagen K, Denmark.
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Rogerson SJ. Malaria in pregnancy and the newborn. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 659:139-52. [PMID: 20204762 DOI: 10.1007/978-1-4419-0981-7_12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Stephen J Rogerson
- Department of Medicine (RMH/WH), Post Office Royal Melbourne Hospital, Parkville, VIC, Australia.
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37
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Khunrae P, Dahlbäck M, Nielsen MA, Andersen G, Ditlev SB, Resende M, Pinto VV, Theander TG, Higgins MK, Salanti A. Full-length recombinant Plasmodium falciparum VAR2CSA binds specifically to CSPG and induces potent parasite adhesion-blocking antibodies. J Mol Biol 2010; 397:826-34. [PMID: 20109466 PMCID: PMC3715698 DOI: 10.1016/j.jmb.2010.01.040] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 01/08/2010] [Accepted: 01/19/2010] [Indexed: 11/27/2022]
Abstract
Plasmodium falciparum malaria remains one of the world's leading causes of human suffering and poverty. Each year, the disease takes 1–3 million lives, mainly in sub-Saharan Africa. The adhesion of infected erythrocytes (IEs) to vascular endothelium or placenta is the key event in the pathogenesis of severe P. falciparum infection. In pregnant women, the parasites express a single and unique member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family named VAR2CSA, which is associated with the ability of the IEs to adhere specifically to chondroitin sulphate A (CSA) in the placenta. Several Duffy-binding-like domains from VAR2CSA molecules have been shown in vitro to bind to CSA, but it has also been demonstrated that Duffy-binding-like domains from PfEMP1 proteins other than VAR2CSA can bind CSA. In addition, the specificity of the binding of VAR2CSA domains to glycosaminoglycans does not match that of VAR2CSA-expressing IEs. This has led to speculation that the domains of native VAR2CSA need to come together to form a specific binding site or that VAR2CSA might bind to CSA through a bridging molecule. Here, we describe the expression and purification of the complete extracellular region of VAR2CSA secreted at high yields from insect cells. Using surface plasmon resonance, we demonstrate that VAR2CSA alone binds with nanomolar affinity to human chondroitin sulphate proteoglycan and with significantly weaker affinity to other glycosaminoglycans, showing a specificity similar to that observed for IEs. Antibodies raised against full-length VAR2CSA completely inhibit recombinant VAR2CSA binding, as well as parasite binding to chondroitin sulphate proteoglycan. This is the first study to describe the successful production and functionality of a full-length PfEMP1. The specificity of the binding and anti-adhesion potency of induced IgG, together with high-yield production, encourages the use of full-length PfEMP1 in vaccine development strategies.
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Affiliation(s)
- Pongsak Khunrae
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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38
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Chondroitin sulphate A (CSA)-binding of single recombinant Duffy-binding-like domains is not restricted to Plasmodium falciparum Erythrocyte Membrane Protein 1 expressed by CSA-binding parasites. Int J Parasitol 2009; 39:1195-204. [PMID: 19324047 DOI: 10.1016/j.ijpara.2009.02.022] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 01/21/2009] [Accepted: 02/17/2009] [Indexed: 11/23/2022]
Abstract
Individuals living in areas with high Plasmodium falciparum transmission acquire immunity to malaria over time and adults have a markedly reduced risk of contracting severe disease. However, pregnant women constitute an important exception. Pregnancy-associated malaria is a major cause of mother and offspring morbidity, such as severe maternal anaemia and low birth-weight, and is characterised by selective accumulation of parasite-infected erythrocytes (IE) in the placenta. A P. falciparum protein named VAR2CSA, which belongs to the large P. falciparum Erythrocyte Membrane Protein 1 (PfEMP1) family, enables the IE to bind chondroitin sulphate A (CSA) in the placenta. Knock-out studies have demonstrated the exclusive capacity of VAR2CSA to mediate IE binding to CSA, and it has been shown that four of the six Duffy-binding-like (DBL) domains of VAR2CSA have the ability to bind CSA in vitro. In this study, we confirm the CSA-binding of these DBL domains, however, the analysis of a number of DBL domains of a non-VAR2CSA origin shows that CSA-binding is not exclusively restricted to VAR2CSA DBL domains. Furthermore, we show that the VAR2CSA DBL domains as well as other DBL domains also bind heparan sulphate. These data explain a number of publications describing CSA-binding domains derived from PfEMP1 antigens not involved in placental adhesion. The data suggest that the ability of single domains to bind CSA does not predict the functional capacity of the whole PfEMP1 and raises doubt whether the CSA-binding domains of native VAR2CSA have been correctly identified.
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Andersen P, Nielsen MA, Resende M, Rask TS, Dahlbäck M, Theander T, Lund O, Salanti A. Structural insight into epitopes in the pregnancy-associated malaria protein VAR2CSA. PLoS Pathog 2008; 4:e42. [PMID: 18282103 PMCID: PMC2242842 DOI: 10.1371/journal.ppat.0040042] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Accepted: 01/07/2008] [Indexed: 11/21/2022] Open
Abstract
Pregnancy-associated malaria is caused by Plasmodium falciparum malaria parasites binding specifically to chondroitin sulfate A in the placenta. This sequestration of parasites is a major cause of low birth weight in infants and anemia in the mothers. VAR2CSA, a polymorphic multi-domain protein of the PfEMP1 family, is the main parasite ligand for CSA binding, and identification of protective antibody epitopes is essential for VAR2CSA vaccine development. Attempts to determine the crystallographic structures of VAR2CSA or its domains have not been successful yet. In this study, we propose 3D models for each of the VAR2CSA DBL domains and we show that regions in the fold of VAR2CSA inter-domain 2 and a PfEMP1 CIDR domain seem to be homologous to the EBA-175 and Pkα-DBL fold. This suggests that ID2 could be a functional domain. We also identify regions of VAR2CSA present on the surface of native VAR2CSA by comparing reactivity of plasma containing anti-VAR2CSA antibodies in peptide array experiments before and after incubation with native VAR2CSA. By this method we identify conserved VAR2CSA regions targeted by antibodies that react with the native molecule expressed on infected erythrocytes. By mapping the data onto the DBL models we present evidence suggesting that the S1+S2 DBL sub-domains are generally surface-exposed in most domains, whereas the S3 sub-domains are less exposed in native VAR2CSA. These results comprise an important step towards understanding the structure of VAR2CSA on the surface of CSA-binding infected erythrocytes. Individuals living in areas with high Plasmodium falciparum transmission acquire immunity to malaria over time and adults have markedly reduced risk of getting severe disease. However, pregnant women constitute an important exception, and they become more susceptible to malaria during pregnancy. This so called pregnancy-associated malaria (PAM) has severe consequences for both mother and child, and a vaccine would save hundreds of thousands of lives each year. PAM is caused by P. falciparum–infected red blood cells that bind to receptors in the placenta. By binding to the placental tissue, the parasites avoid being filtered though the spleen where they would have been killed. The protein mediating this placental binding is a very large multidomain and variant protein named VAR2CSA. Using structural modeling of VAR2CSA and antibody reagents from women who have had PAM, we show that antibodies tend to bind in similar regions, on one side of the individual VAR2CSA domains. In addition, we show that highly conserved parts of this variant protein are accessible for antibodies. This finding correlates with epidemiological data showing that woman acquire immunity towards PAM relatively fast, and the identification of these epitopes is thus a major step towards a protective vaccine.
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Affiliation(s)
| | - Morten A Nielsen
- Centre for Medical Parasitology at University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Mafalda Resende
- Centre for Medical Parasitology at University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thomas S Rask
- Center for Biological Sequence Analysis, BioCentrum-DTU, Denmark
| | - Madeleine Dahlbäck
- Centre for Medical Parasitology at University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Thor Theander
- Centre for Medical Parasitology at University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ole Lund
- Center for Biological Sequence Analysis, BioCentrum-DTU, Denmark
| | - Ali Salanti
- Centre for Medical Parasitology at University of Copenhagen and Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- * To whom correspondence should be addressed. E-mail:
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Resende M, Nielsen MA, Dahlbäck M, Ditlev SB, Andersen P, Sander AF, Ndam NT, Theander TG, Salanti A. Identification of glycosaminoglycan binding regions in the Plasmodium falciparum encoded placental sequestration ligand, VAR2CSA. Malar J 2008; 7:104. [PMID: 18534039 PMCID: PMC2430714 DOI: 10.1186/1475-2875-7-104] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Accepted: 06/06/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pregnancy malaria is caused by Plasmodium falciparum-infected erythrocytes binding the placental receptor chondroitin sulfate A (CSA). This results in accumulation of parasites in the placenta with severe clinical consequences for the mother and her unborn child. Women become resistant to placental malaria as antibodies are acquired which specifically target the surface of infected erythrocytes binding in the placenta. VAR2CSA is most likely the parasite-encoded protein which mediates binding to the placental receptor CSA. Several domains have been shown to bind CSA in vitro; and it is apparent that a VAR2CSA-based vaccine cannot accommodate all the CSA binding domains and serovariants. It is thus of high priority to define minimal ligand binding regions throughout the VAR2CSA molecule. METHODS To define minimal CSA-binding regions/peptides of VAR2CSA, a phage display library based on the entire var2csa coding region was constructed. This library was screened on immobilized CSA and cells expressing CSA resulting in a limited number of CSA-binding phages. Antibodies against these peptides were affinity purified and tested for reactivity against CSA-binding infected erythrocytes. RESULTS The most frequently identified phages expressed peptides residing in the parts of VAR2CSA previously defined as CSA binding. In addition, most of the binding regions mapped to surface-exposed parts of VAR2CSA. The binding of a DBL2X peptide to CSA was confirmed with a synthetic peptide. Antibodies against a CSA-binding DBL2X peptide reacted with the surface of infected erythrocytes indicating that this epitope is accessible for antibodies on native VAR2CSA on infected erythrocytes. CONCLUSION Short continuous regions of VAR2CSA with affinity for multiple types of CSA were defined. A number of these regions localize to CSA-binding domains and to surface-exposed regions within these domains and a synthetic peptide corresponding to a peptide sequence in DBL2 was shown to bind to CSA and not to CSC. It is likely that some of these epitopes are involved in native parasite CSA adhesion. However, antibodies directed against single epitopes did not inhibit parasite adhesion. This study supports phage display as a technique to identify CSA-binding regions of large proteins such as VAR2CSA.
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Affiliation(s)
- Mafalda Resende
- Centre for Medical Parasitology, Institute of International Health Immunology and Microbiology, University of Copenhagen, Department of Clinical Microbiology, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark.
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Bengtsson D, Sowa KM, Salanti A, Jensen AT, Joergensen L, Turner L, Theander TG, Arnot DE. A method for visualizing surface-exposed and internal PfEMP1 adhesion antigens in Plasmodium falciparum infected erythrocytes. Malar J 2008; 7:101. [PMID: 18533996 PMCID: PMC2453135 DOI: 10.1186/1475-2875-7-101] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Accepted: 06/05/2008] [Indexed: 11/17/2022] Open
Abstract
Background The insertion of parasite antigens into the host erythrocyte membrane and the structure and distribution of Plasmodium falciparum adhesion receptors on that membrane are poorly understood. Laser scanning confocal microscopy (LSCM) and a novel labelling and fixation method have been used to obtain high resolution immuno-fluorescent images of erythrocyte surface PfEMP1 and internal antigens which allow analysis of the accumulation of PfEMP1 on the erythrocyte membrane during asexual development. Methods A novel staining technique has been developed which permits distinction between erythrocyte surface PfEMP1 and intracellular PfEMP1, in parasites whose nuclear material is exceptionally well resolved. Primary antibody detection by fluorescence is carried out on the live parasitized erythrocyte. The surface labelled cells are then fixed using paraformaldehyde and permeabilized with a non-ionic detergent to permit access of antibodies to internal parasite antigens. Differentiation between surface and internal antigens is achieved using antibodies labelled with different fluorochromes and confocal microscopy Results Surface exposed PfEMP1 is first detectable by antibodies at the trophozoite stage of intracellular parasite development although the improved detection method indicates that there are differences between different laboratory isolates in the kinetics of accumulation of surface-exposed PfEMP1. Conclusion A sensitive method for labelling surface and internal PfEMP1 with up to three different fluorochromes has been developed for laser scanning confocal optical microscopy and the analysis of the developmental expression of malaria adhesion antigens.
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Affiliation(s)
- Dominique Bengtsson
- Centre for Medical Parasitology, Department of International Health, Immunology & Microbiology, Faculty of Health Sciences, University of Copenhagen, Copenhagen K, Denmark.
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Mok BW, Ribacke U, Rasti N, Kironde F, Chen Q, Nilsson P, Wahlgren M. Default Pathway of var2csa switching and translational repression in Plasmodium falciparum. PLoS One 2008; 3:e1982. [PMID: 18431472 PMCID: PMC2292259 DOI: 10.1371/journal.pone.0001982] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 03/02/2008] [Indexed: 11/19/2022] Open
Abstract
Antigenic variation is a subtle process of fundamental importance to the survival of a microbial pathogen. In Plasmodium falciparum malaria, PfEMP1 is the major variable antigen and adhesin expressed at the surface of the infected erythrocyte, which is encoded for by members of a family of 60 var-genes. Peri-nuclear repositioning and epigenetic mechanisms control their mono-allelic expression. The switching of PfEMP1 depends in part on variable transition rates and short-lived immune responses to shared minor epitopes. Here we show var-genes to switch to a common gene that is highly transcribed, but sparsely translated into PfEMP1 and not expressed at the erythrocyte surface. Highly clonal and adhesive P. falciparum, which expressed distinct var-genes and the corresponding PfEMP1s at onset, were propagated without enrichment or panning. The parasites successively and spontaneously switched to transcribe a shared var-gene (var2csa) matched by the loss of PfEMP1 surface expression and host cell-binding. The var2csa gene repositioned in the peri-nuclear area upon activation, away from the telomeric clusters and heterochromatin to transcribe spliced, full-length RNA. Despite abundant transcripts, the level of intracellular PfEMP1 was low suggesting post-transcriptional mechanisms to partake in protein expression. In vivo, off-switching and translational repression may constitute one pathway, among others, coordinating PfEMP1 expression.
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Affiliation(s)
- Bobo W. Mok
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Ulf Ribacke
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Niloofar Rasti
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Fred Kironde
- Department of Biochemistry, Faculty of Medicine, Makerere University, Kampala, Uganda
| | - Qijun Chen
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
| | - Peter Nilsson
- Department of Gene Technology, School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
| | - Mats Wahlgren
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
- Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden
- * E-mail:
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Characterization of VAR2CSA-deficient Plasmodium falciparum-infected erythrocytes selected for adhesion to the BeWo placental cell line. Malar J 2008; 7:51. [PMID: 18364051 PMCID: PMC2329659 DOI: 10.1186/1475-2875-7-51] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 03/26/2008] [Indexed: 11/19/2022] Open
Abstract
Background Malaria in pregnancy is characterized by accumulation of infected erythrocytes (IE) in the placenta. The key ligand identified as mediating this process is a Plasmodium falciparum erythrocyte membrane protein 1 family member, termed VAR2CSA. VAR2CSA appears to be the main ligand responsible for adhesion to chondroitin sulphate A (CSA). Whether other PfEMP1 molecules can also mediate placental adhesion, independent of CSA binding, is unclear. Methods The parasite line CS2 carrying a disrupted var2csa gene (CS2KO) was selected for adhesion to the BeWo choriocarcinoma cell line, which has been proposed as a model for placental malaria. The selected and control IE were tested for adhesion to placental sections and flow cytometry was used to measure recognition of IE by three serum sets from malaria-exposed men and women. Results Wild-type CS2 adhere to BeWo and placental tissue via CSA. CS2KO IE were successfully selected for adhesion to BeWo, and adhered by a CSA-independent mechanism. They bound to immobilized ICAM-1 and CD36. BeWo-selected CS2KO bound at moderate levels to placental sections, but most binding was to placental villi rather than to the syncytiotrophoblast to which IE adherence occurs in vivo. This binding was inhibited by a blocking antibody to CD36 but not to ICAM-1. As expected, sera from malaria-exposed adults recognized CS2 IE in a gender and parity dependent manner. In one serum set, there was a similar but less pronounced pattern of antibody binding to selected CS2KO IE, but this was not seen in two others. One var gene, It4var19, was particularly abundant in the selected line and was detected as full length transcripts in BeWo-selected IE, but not unselected CS2KO. Conclusion This study suggests that IE with characteristics similar to the CS2KO have a limited role in the pathogenesis of placental malaria. VAR2CSA appear to be the major ligand for placental adhesion, and could be the basis for a vaccine against pregnancy malaria.
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Tuikue Ndam N, Bischoff E, Proux C, Lavstsen T, Salanti A, Guitard J, Nielsen MA, Coppée JY, Gaye A, Theander T, David PH, Deloron P. Plasmodium falciparum transcriptome analysis reveals pregnancy malaria associated gene expression. PLoS One 2008; 3:e1855. [PMID: 18365010 PMCID: PMC2267001 DOI: 10.1371/journal.pone.0001855] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Accepted: 02/20/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Pregnancy-associated malaria (PAM) causing maternal anemia and low birth weight is among the multiple manifestations of Plasmodium falciparum malaria. Infected erythrocytes (iEs) can acquire various adhesive properties that mediate the clinical severity of malaria. Recent advances on the molecular basis of virulence and immune evasion have helped identify var2csa as a PAM-specific var gene. METHODOLOGY/PRINCIPAL FINDINGS The present study presents a genome-wide microarray transcript analysis of 18 P. falciparum parasite isolates freshly collected from the placenta. The proportion of PAM over-expressed genes located in subtelomeric regions as well as that of PAM over-expressed genes predicted to be exported were higher than expected compared to the whole genome. The identification of novel parasite molecules with specificity to PAM and which are likely involved in host-pathogen interactions and placental tropism is described. One of these proteins, PFI1785w, was further characterized as the product of a two-exon PHIST gene, and was more often recognized by serum samples from P. falciparum-exposed women than from men. CONCLUSIONS/SIGNIFICANCE These findings suggest that other parasite proteins, such as PFI1785w, may contribute beside VAR2CSA to the pathogenesis of PAM. These data may be very valuable for future vaccine development.
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Affiliation(s)
- Nicaise Tuikue Ndam
- Institut de Recherche pour le Développement, UR010 at Université Paris Descartes, Mother and Child Health in the Tropics, Faculté de Pharmacie, Paris, France.
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Achur RN, Muthusamy A, Madhunapantula SV, Gowda DC. Binding affinity of Plasmodium falciparum-infected erythrocytes from infected placentas and laboratory selected strains to chondroitin 4-sulfate. Mol Biochem Parasitol 2008; 159:79-84. [PMID: 18359524 DOI: 10.1016/j.molbiopara.2008.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 02/05/2008] [Accepted: 02/07/2008] [Indexed: 11/26/2022]
Abstract
The adherence of Plasmodium falciparum-infected red blood cells (IRBCs) in human placenta is mediated by chondroitin 4-sulfate (C4S). The C4S-adherent parasites selected from laboratory strains have been widely used for determining the C4S structural elements involved in IRBC binding and for the identification of parasite adhesive protein(s). However, as far as we know, the relative binding strength of the placental versus laboratory-selected parasites has not been reported. In this study, we show that IRBCs from the infected placentas bind to C4S about 3-fold higher than those selected for C4S adherence from laboratory strains. Although adherent parasites selected from several laboratory strains have comparable binding strengths, the one obtained from 3D7 parasites designated as 3D7N61 used for malaria genome sequencing, exhibits markedly lower binding strength. Furthermore, 3D7N61-CSA parasites lose most of the binding capacity by tenth generation in continuous culture.
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Affiliation(s)
- Rajeshwara N Achur
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Nantulya FN, Kengeya-Kayondo JF, Ogundahunsi OAT. Research Themes and Advances in Malaria Research Capacity Made by the Multilateral Initiative on Malaria. Am J Trop Med Hyg 2007. [DOI: 10.4269/ajtmh.77.6.suppl.303] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Florence N. Nantulya
- Special Program for Research and Training in Tropical Diseases, World Health Organization, Geneva, Switzerland; Chemin du Joran, Nyon, Switzerland
| | - Jane F. Kengeya-Kayondo
- Special Program for Research and Training in Tropical Diseases, World Health Organization, Geneva, Switzerland; Chemin du Joran, Nyon, Switzerland
| | - Olumide A. T. Ogundahunsi
- Special Program for Research and Training in Tropical Diseases, World Health Organization, Geneva, Switzerland; Chemin du Joran, Nyon, Switzerland
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Viebig NK, Levin E, Dechavanne S, Rogerson SJ, Gysin J, Smith JD, Scherf A, Gamain B. Disruption of var2csa gene impairs placental malaria associated adhesion phenotype. PLoS One 2007; 2:e910. [PMID: 17878945 PMCID: PMC1975670 DOI: 10.1371/journal.pone.0000910] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 08/29/2007] [Indexed: 11/25/2022] Open
Abstract
Infection with Plasmodium falciparum during pregnancy is one of the major causes of malaria related morbidity and mortality in newborn and mothers. The complications of pregnancy-associated malaria result mainly from massive adhesion of Plasmodium falciparum-infected erythrocytes (IE) to chondroitin sulfate A (CSA) present in the placental intervillous blood spaces. Var2CSA, a member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family is the predominant parasite ligand mediating CSA binding. However, experimental evidence suggests that other host receptors, such as hyaluronic acid (HA) and the neonatal Fc receptor, may also support placental binding. Here we used parasites in which var2csa was genetically disrupted to evaluate the contribution of these receptors to placental sequestration and to identify additional adhesion receptors that may be involved in pregnancy-associated malaria. By comparison to the wild-type parasites, the FCR3Δvar2csa mutants could not be selected for HA adhesion, indicating that var2csa is not only essential for IE cytoadhesion to the placental receptor CSA, but also to HA. However, further studies using different pure sources of HA revealed that the previously observed binding results from CSA contamination in the bovine vitreous humor HA preparation. To identify CSA-independent placental interactions, FCR3Δvar2csa mutant parasites were selected for adhesion to the human placental trophoblastic BeWo cell line. BeWo selected parasites revealed a multi-phenotypic adhesion population expressing multiple var genes. However, these parasites did not cytoadhere specifically to the syncytiotrophoblast lining of placental cryosections and were not recognized by sera from malaria-exposed women in a parity dependent manner, indicating that the surface molecules present on the surface of the BeWo selected population are not specifically expressed during the course of pregnancy-associated malaria. Taken together, these results demonstrate that the placental malaria associated phenotype can not be restored in FCR3Δvar2csa mutant parasites and highlight the key role of var2CSA in pregnancy malaria pathogenesis and for vaccine development.
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Affiliation(s)
- Nicola K. Viebig
- Unité de Biologie des Interactions Hôte-Parasite, Institut Pasteur and CNRS, Paris, France
| | - Emily Levin
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Sébastien Dechavanne
- Unité de Parasitologie Expérimentale, Université de la Méditerranée, Marseille, France
| | - Stephen J. Rogerson
- Department of Medicine, University of Melbourne, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Jürg Gysin
- Unité de Parasitologie Expérimentale, Université de la Méditerranée, Marseille, France
| | - Joseph D. Smith
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Artur Scherf
- Unité de Biologie des Interactions Hôte-Parasite, Institut Pasteur and CNRS, Paris, France
- * To whom correspondence should be addressed. E-mail: (BG), (AS)
| | - Benoit Gamain
- Unité de Biologie des Interactions Hôte-Parasite, Institut Pasteur and CNRS, Paris, France
- * To whom correspondence should be addressed. E-mail: (BG), (AS)
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Nielsen MA, Resende M, Alifrangis M, Turner L, Hviid L, Theander TG, Salanti A. Plasmodium falciparum: VAR2CSA expressed during pregnancy-associated malaria is partially resistant to proteolytic cleavage by trypsin. Exp Parasitol 2007; 117:1-8. [PMID: 17442305 DOI: 10.1016/j.exppara.2007.03.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 03/01/2007] [Accepted: 03/02/2007] [Indexed: 10/23/2022]
Abstract
In areas of high Plasmodium falciparum transmission, immunity to malaria is acquired during childhood, so that adults in general are clinically immune. One exception is that first-time pregnant women are susceptible to pregnancy-associated malaria caused by accumulation of parasites in the placenta. Pregnancy-associated variant surface antigens (VSAPAM) mediate binding of the infected erythrocyte to chondroitin sulphate proteoglycans in the placental intervillous space. Several lines of evidence indicate that the molecular identity of VSAPAM is VAR2CSA, a relatively conserved member of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family. While native PfEMP1 molecules expressed on the infected erythrocyte surface generally are sensitive to mild trypsinization, some VSAPAM expressing parasite lines are resistant. This finding has led to the suggestion that molecules other than PfEMP1, or at least several different PfEMP1 families mediate the VSAPAM phenotype. To address this issue we incubated three different VAR2CSA expressing parasite lines with trypsin and found that polymorphic VAR2CSA variants can be both protease resistant and sensitive. Trypsin treatment resulted in loss of ability to adhere to CSA and loss of sex-specific antibody recognition of the surface of the infected erythrocyte in one sensitive isolate, whereas CSA binding and sex-specific recognition were largely unaffected by trypsin treatment in two resistant isolates. These results support the hypothesis that VAR2CSA mediates the adhesive and antigenic phenotypes shown by parasites causing placental malaria.
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Affiliation(s)
- Morten A Nielsen
- Centre for Medical Parasitology, Department of Infectious Diseases M4701, Copenhagen University Hospital (Rigshospitalet), Blegdamsvej 9, 2100 Copenhagen Ø, Denmark.
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Rogerson SJ, Hviid L, Duffy PE, Leke RFG, Taylor DW. Malaria in pregnancy: pathogenesis and immunity. THE LANCET. INFECTIOUS DISEASES 2007; 7:105-17. [PMID: 17251081 DOI: 10.1016/s1473-3099(07)70022-1] [Citation(s) in RCA: 362] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Understanding of the biological basis for susceptibility to malaria in pregnancy was recently advanced by the discovery that erythrocytes infected with Plasmodium falciparum accumulate in the placenta through adhesion to molecules such as chondroitin sulphate A. Antibody recognition of placental infected erythrocytes is dependent on sex and gravidity, and could protect from malaria complications. Moreover, a conserved parasite gene-var2csa-has been associated with placental malaria, suggesting that its product might be an appropriate vaccine candidate. By contrast, our understanding of placental immunopathology and how this contributes to anaemia and low birthweight remains restricted, although inflammatory cytokines produced by T cells, macrophages, and other cells are clearly important. Studies that unravel the role of host response to malaria in pathology and protection in the placenta, and that dissect the relation between timing of infection and outcome, could allow improved targeting of preventive treatments and development of a vaccine for use in pregnant women.
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Affiliation(s)
- Stephen J Rogerson
- Department of Medicine, University of Melbourne, Parkville, Victoria, Australia.
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50
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Adams Y, Schwartz-Albiez R, McCarthy JS, Andrews KT. Effect of cytokine treatment on the in vitro expression of the P. falciparum adhesion receptor chondroitin-4-sulphate on the surface of human choriocarcinoma (BeWo) cells. Parasitol Res 2007; 101:479-83. [PMID: 17520289 DOI: 10.1007/s00436-007-0473-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2006] [Accepted: 01/22/2007] [Indexed: 11/30/2022]
Abstract
BeWo human choriocarcinoma cells have recently been identified as an in vitro model of adhesion of Plasmodium falciparum-infected erythrocytes to the major placental receptor chondroitn-4-sulphate (CSA). In this study, we show that treatment of BeWo cells with tumour necrosis factor-alpha and/or interferon-gamma, cytokines linked with pregnancy-associated malaria and poor pregnancy outcome, does not alter the expression of cell surface CSA. BeWo cells do not express the common P. falciparum adhesion receptor cluster of differentiation 36 (CD36) on the cell surface, and this was unchanged after treatment with cytokines. These data demonstrate that in vitro cultured BeWo cells mimic the P. falciparum adhesion receptor expression profile of ex vivo placental cytotrophoblast cells.
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Affiliation(s)
- Yvonne Adams
- Hygiene-Institut, Abteilung Parasitologie, Universität Heidelberg, Im Neuenheimer Feld 324, Heidelberg, 69120, Germany
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