1
|
Gnidehou S, Yanow SK. VAR2CSA Antibodies in Non-Pregnant Populations. Trends Parasitol 2020; 37:65-76. [PMID: 33067131 DOI: 10.1016/j.pt.2020.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/16/2020] [Accepted: 09/18/2020] [Indexed: 11/18/2022]
Abstract
The Plasmodium falciparum protein VAR2CSA is a critical mediator of placental malaria, and VAR2CSA antibodies (IgGs) are important to protect pregnant women. Although infrequently detected outside pregnancy, VAR2CSA IgGs were reported in men and children from Colombia and Brazil and in select African populations. These findings raise questions about the specificity of VAR2CSA IgGs and the mechanisms by which they are acquired outside pregnancy. Here we review the data on VAR2CSA IgGs in men and children from different malaria-endemic regions. We discuss experimental factors that may affect interpretation of the serological data and consider the biological relevance of VAR2CSA IgGs in non-pregnant populations. We propose potential mechanisms for the acquisition of VARCSA IgGs outside of pregnancy. We identify knowledge gaps and research priorities.
Collapse
Affiliation(s)
- Sedami Gnidehou
- Campus Saint-Jean, University of Alberta, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.
| | - Stephanie K Yanow
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; School of Public Health, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
2
|
Gbédandé K, Fievet N, Viwami F, Ezinmegnon S, Issifou S, Chippaux JP, Dossou Y, Moutairou K, Massougbodji A, Ndam N, de Jongh WA, Søgaard TMM, Salanti A, Nielsen MA, Esen M, Mordmüller B, Deloron P, Luty AJF. Clinical development of a VAR2CSA-based placental malaria vaccine PAMVAC: Quantifying vaccine antigen-specific memory B & T cell activity in Beninese primigravidae. Vaccine 2017; 35:3474-3481. [PMID: 28527688 DOI: 10.1016/j.vaccine.2017.05.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/04/2017] [Accepted: 05/06/2017] [Indexed: 11/18/2022]
Abstract
BACKGROUND The antigen VAR2CSA plays a pivotal role in the pathophysiology of pregnancy-associated malaria (PAM) caused by Plasmodium falciparum. A VAR2CSA-based vaccine candidate, PAMVAC, is under development by an EU-funded multi-country consortium (PlacMalVac project). As part of PAMVAC's clinical development, we quantified naturally acquired vaccine antigen-specific memory B and T cell responses in Beninese primigravidae recruited at the beginning of pregnancy and followed up to delivery and beyond. METHODS Clinical and parasitological histories were compiled from monthly clinic visits. On 4 occasions (first and fifth month of pregnancy, delivery, 6months post-delivery) peripheral blood mononuclear cells were isolated for in vitro assays. PAMVAC-specific memory B cells as well as those specific for a PAM unrelated P. falciparum antigen (PfEMP1-CIDR1a) and for tetanus toxoid were quantified by ELISpot. Memory T cell responses were assessed by quantifying cytokines (IL-5, IL-6, IL-10, IL-13, IFN-γ, TNF-α) in supernatants of cells stimulated in vitro either with PAMVAC, or mitogen (PHA). RESULTS Both tetanus toxoid- and PAMVAC-specific memory B cell frequencies increased to reach peak levels in the 5th month and at delivery, respectively and persisted post-delivery. The frequency of CIDR1a-specific memory B cells was stable during pregnancy, but declined post-delivery. The cumulated prevalence of infection with P. falciparum during pregnancy was 61% by microscopy. In women with a history of such infections, a significantly higher frequency of PAMVAC-specific memory B cells was observed at delivery. PAMVAC-specific pro-inflammatory (IFN-γ, TNF) responses tended to be higher at delivery in those with a history of infection. Mitogen-induced IL-5/IL-13 responses were significantly enhanced in the same women. CONCLUSIONS PAMVAC-specific memory B cells are induced during first pregnancies and are maintained post-delivery. Women with a T helper cell profile biased towards production of Th2-type cytokines have a greater risk of infection with P. falciparum.
Collapse
Affiliation(s)
- Komi Gbédandé
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin; Département de Biochimie et de Biologie Cellulaire, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Benin; MERIT UMR D216, Institut de Recherche pour le Développement, Université Paris Descartes, COMUE Sorbonne Paris Cité, 75006 Paris, France.
| | - Nadine Fievet
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin; MERIT UMR D216, Institut de Recherche pour le Développement, Université Paris Descartes, COMUE Sorbonne Paris Cité, 75006 Paris, France.
| | - Firmine Viwami
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin.
| | - Sem Ezinmegnon
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin.
| | - Saadou Issifou
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin.
| | - Jean-Philippe Chippaux
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin; MERIT UMR D216, Institut de Recherche pour le Développement, Université Paris Descartes, COMUE Sorbonne Paris Cité, 75006 Paris, France.
| | - Yannelle Dossou
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin.
| | - Kabirou Moutairou
- Département de Biochimie et de Biologie Cellulaire, Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Benin.
| | - Achille Massougbodji
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin.
| | - Nicaise Ndam
- MERIT UMR D216, Institut de Recherche pour le Développement, Université Paris Descartes, COMUE Sorbonne Paris Cité, 75006 Paris, France.
| | | | - T Max M Søgaard
- ExpreS(2)ion Biotechnologies SCION-DTU Science Park DK-2970, Hoersholm, Denmark.
| | - Ali Salanti
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
| | - Morten A Nielsen
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
| | - Meral Esen
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, Tübingen, Germany.
| | - Benjamin Mordmüller
- Institut für Tropenmedizin, Eberhard Karls Universität Tübingen, Tübingen, Germany.
| | - Philippe Deloron
- MERIT UMR D216, Institut de Recherche pour le Développement, Université Paris Descartes, COMUE Sorbonne Paris Cité, 75006 Paris, France.
| | - Adrian J F Luty
- Centre d'Etude et de Recherche sur le Paludisme Associé à la Grossesse et à l'Enfance (CERPAGE), Faculté des Sciences de la Santé, Université d'Abomey-Calavi, Benin; MERIT UMR D216, Institut de Recherche pour le Développement, Université Paris Descartes, COMUE Sorbonne Paris Cité, 75006 Paris, France.
| |
Collapse
|
3
|
Requena P, Arévalo-Herrera M, Menegon M, Martínez-Espinosa FE, Padilla N, Bôtto-Menezes C, Malheiro A, Hans D, Castellanos ME, Robinson L, Samol P, Kochar S, Kochar SK, Kochar DK, Desai M, Sanz S, Quintó L, Mayor A, Rogerson S, Mueller I, Severini C, Del Portillo HA, Bardají A, Chitnis CC, Menéndez C, Dobaño C. Naturally Acquired Binding-Inhibitory Antibodies to Plasmodium vivax Duffy Binding Protein in Pregnant Women Are Associated with Higher Birth Weight in a Multicenter Study. Front Immunol 2017; 8:163. [PMID: 28261219 PMCID: PMC5313505 DOI: 10.3389/fimmu.2017.00163] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/31/2017] [Indexed: 12/11/2022] Open
Abstract
A vaccine to eliminate malaria would need a multi-stage and multi-species composition to achieve robust protection, but the lack of knowledge about antigen targets and mechanisms of protection precludes the development of fully efficacious malaria vaccines, especially for Plasmodium vivax (Pv). Pregnant women constitute a risk population who would greatly benefit from a vaccine preventing the adverse events of Plasmodium infection during gestation. We hypothesized that functional immune responses against putative targets of naturally acquired immunity to malaria and vaccine candidates will be associated with protection against malaria infection and/or poor outcomes during pregnancy. We measured (i) IgG responses to a large panel of Pv and Plasmodium falciparum (Pf) antigens, (ii) the capacity of anti-Pv ligand Duffy binding protein (PvDBP) antibodies to inhibit binding to Duffy antigen, and (iii) cellular immune responses to two Pv antigens, in a subset of 1,056 pregnant women from Brazil, Colombia, Guatemala, India, and Papua New Guinea (PNG). There were significant intraspecies and interspecies correlations for most antibody responses (e.g., PfMSP119 versus PfAMA1, Spearman’s rho = 0.81). Women from PNG and Colombia had the highest levels of IgG overall. Submicroscopic infections seemed sufficient to boost antibody responses in Guatemala but not antigen-specific cellular responses in PNG. Brazil had the highest percentage of Duffy binding inhibition (p-values versus Colombia: 0.040; Guatemala: 0.047; India: 0.003, and PNG: 0.153) despite having low anti-PvDBP IgG levels. Almost all antibodies had a positive association with present infection, and coinfection with the other species increased this association. Anti-PvDBP, anti-PfMSP1, and anti-PfAMA1 IgG levels at recruitment were positively associated with infection at delivery (p-values: 0.010, 0.003, and 0.023, respectively), suggesting that they are markers of malaria exposure. Peripheral blood mononuclear cells from Pv-infected women presented fewer CD8+IFN-γ+ T cells and secreted more G-CSF and IL-4 independently of the stimulus used in vitro. Functional anti-PvDBP levels at recruitment had a positive association with birth weight (difference per doubling antibody levels: 45 g, p-value: 0.046). Thus, naturally acquired binding-inhibitory antibodies to PvDBP might confer protection against poor outcomes of Pv malaria in pregnancy.
Collapse
Affiliation(s)
- Pilar Requena
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| | | | | | - Flor E Martínez-Espinosa
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Amazonas, Brazil; Instituto Leônidas e Maria Deane (ILMD/Fiocruz Amazonia), Amazonia, Brazil
| | - Norma Padilla
- Centro de Estudios en Salud, Universidad del Valle de Guatemala , Guatemala City , Guatemala
| | - Camila Bôtto-Menezes
- Instituto Leônidas e Maria Deane (ILMD/Fiocruz Amazonia), Amazonia, Brazil; Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
| | - Adriana Malheiro
- Instituto de Ciências Biológicas, Universidade Federal do Amazonas , Manaus , Brazil
| | - Dhiraj Hans
- International Center for Genetic Engineering and Biotechnology , Delhi , India
| | | | - Leanne Robinson
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea; Macfarlane Burnet Institute of Medical Research, Melbourne, VIC, Australia; Walter and Eliza Hall Institute, Parkville, VIC, Australia
| | - Paula Samol
- Papua New Guinea Institute of Medical Research , Madang , Papua New Guinea
| | - Swati Kochar
- Medical College Bikaner , Bikaner, Rajasthan , India
| | | | | | - Meghna Desai
- Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Malaria Branch , Atlanta, GA , USA
| | - Sergi Sanz
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| | - Llorenç Quintó
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| | - Alfredo Mayor
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| | | | - Ivo Mueller
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Catalonia, Spain; Walter and Eliza Hall Institute, Parkville, VIC, Australia
| | | | - Hernando A Del Portillo
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Catalonia, Spain; ICREA, Barcelona, Spain
| | - Azucena Bardají
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| | - Chetan C Chitnis
- International Center for Genetic Engineering and Biotechnology , Delhi , India
| | - Clara Menéndez
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| | - Carlota Dobaño
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona , Barcelona, Catalonia , Spain
| |
Collapse
|
4
|
Fried M, Duffy PE. Designing a VAR2CSA-based vaccine to prevent placental malaria. Vaccine 2015; 33:7483-8. [PMID: 26469717 PMCID: PMC5077158 DOI: 10.1016/j.vaccine.2015.10.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 09/23/2015] [Accepted: 10/02/2015] [Indexed: 11/29/2022]
Abstract
Placental malaria (PM) due to Plasmodium falciparum is a major cause of maternal, fetal and infant mortality, but the mechanisms of pathogenesis and protective immunity are relatively well-understood for this condition, providing a path for vaccine development. P. falciparum parasites bind to chondroitin sulfate A (CSA) to sequester in the placenta, and women become resistant over 1–2 pregnancies as they acquire antibodies that block adhesion to CSA. The protein VAR2CSA, a member of the PfEMP1 variant surface antigen family, mediates parasite adhesion to CSA, and is the leading target for a vaccine to prevent PM. Obstacles to PM vaccine development include the large size (~350 kD), high cysteine content, and sequence variation of VAR2CSA. A number of approaches have been taken to identify the combination of VAR2CSA domains and alleles that can induce broadly active antibodies that block adhesion of heterologous parasite isolates to CSA. This review summarizes these approaches, which have examined VAR2CSA fragments for binding activity, antigenicity with naturally acquired antibodies, and immunogenicity in animals for inducing anti-adhesion or surface-reactive antibodies. Two products are expected to enter human clinical studies in the near future based on N-terminal VAR2CSA fragments that have high binding affinity for CSA, and additional proteins preferentially expressed by placental parasites are also being examined for their potential contribution to a PM vaccine.
Collapse
Affiliation(s)
- Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, 5640 Fishers Lane, TWB1/Room 1111, Rockville, MD, USA.
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, NIH, 5640 Fishers Lane, TWB1/Room 1111, Rockville, MD, USA.
| |
Collapse
|
5
|
Rovira-Vallbona E, Monteiro I, Bardají A, Serra-Casas E, Neafsey DE, Quelhas D, Valim C, Alonso P, Dobaño C, Ordi J, Menéndez C, Mayor A. VAR2CSA signatures of high Plasmodium falciparum parasitemia in the placenta. PLoS One 2013; 8:e69753. [PMID: 23936092 PMCID: PMC3723727 DOI: 10.1371/journal.pone.0069753] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 06/11/2013] [Indexed: 11/18/2022] Open
Abstract
Plasmodium falciparum infected erythrocytes (IE) accumulate in the placenta through the interaction between Duffy-binding like (DBL) domains of parasite-encoded ligand VAR2CSA and chondroitin sulphate-A (CSA) receptor. Polymorphisms in these domains, including DBL2X and DBL3X, may affect their antigenicity or CSA-binding affinity, eventually increasing parasitemia and its adverse effects on pregnancy outcomes. A total of 373 DBL2X and 328 DBL3X sequences were obtained from transcripts of 20 placental isolates infecting Mozambican women, resulting in 176 DBL2X and 191 DBL3X unique sequences at the protein level. Sequence alignments were divided in segments containing combinations of correlated polymorphisms and the association of segment sequences with placental parasite density was tested using Bonferroni corrected regression models, taking into consideration the weight of each sequence in the infection. Three DBL2X and three DBL3X segments contained signatures of high parasite density (P<0.003) that were highly prevalent in the parasite population (49-91%). Identified regions included a flexible loop that contributes to DBL3X-CSA interaction and two DBL3X motifs with evidence of positive natural selection. Limited antibody responses against signatures of high parasite density among malaria-exposed pregnant women could not explain the increased placental parasitemia. These results suggest that a higher binding efficiency to CSA rather than reduced antigenicity might provide a biological advantage to parasites with high parasite density signatures in VAR2CSA. Sequences contributing to high parasitemia may be critical for the functional characterization of VAR2CSA and the development of tools against placental malaria.
Collapse
MESH Headings
- Adolescent
- Amino Acid Sequence
- Antibodies, Protozoan/blood
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/genetics
- Antigens, Protozoan/metabolism
- Binding Sites
- Chondroitin Sulfates/chemistry
- Chondroitin Sulfates/metabolism
- Erythrocytes/metabolism
- Erythrocytes/parasitology
- Female
- Humans
- Malaria, Falciparum/immunology
- Malaria, Falciparum/metabolism
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/pathology
- Molecular Docking Simulation
- Molecular Sequence Data
- Placenta/immunology
- Placenta/parasitology
- Placenta/pathology
- Plasmodium falciparum/chemistry
- Plasmodium falciparum/genetics
- Plasmodium falciparum/metabolism
- Pregnancy
- Pregnancy Complications, Parasitic/immunology
- Pregnancy Complications, Parasitic/metabolism
- Pregnancy Complications, Parasitic/parasitology
- Pregnancy Complications, Parasitic/pathology
- Protein Binding
- Protein Structure, Tertiary
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- Transcriptome
- Young Adult
Collapse
Affiliation(s)
- Eduard Rovira-Vallbona
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
| | - Isadora Monteiro
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
| | - Azucena Bardají
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Elisa Serra-Casas
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
| | | | - Diana Quelhas
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Clarissa Valim
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Pedro Alonso
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Carlota Dobaño
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Jaume Ordi
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
- Department of Pathology, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - Clara Menéndez
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Alfredo Mayor
- Barcelona Centre for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- * E-mail:
| |
Collapse
|
6
|
Multilaboratory approach to preclinical evaluation of vaccine immunogens for placental malaria. Infect Immun 2012. [PMID: 23208604 DOI: 10.1128/iai.01106-12] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pregnancy malaria is caused by Plasmodium falciparum-infected erythrocytes that adhere to the placental receptor chondroitin sulfate A (CSA) and sequester in the placenta; women become resistant to pregnancy malaria as they acquire antiadhesion antibodies that target surface proteins of placental parasites. VAR2CSA, a member of the P. falciparum EMP1 variant surface antigen family, is the leading candidate for a pregnancy malaria vaccine. Because VAR2CSA is a high-molecular-weight protein, a vaccine based on the full-length protein may not be feasible. An alternative approach has been to develop a vaccine targeting individual Duffy binding-like (DBL) domains. In this study, a consortium of laboratories under the Pregnancy Malaria Initiative compared the functional activity of antiadhesion antibodies elicited by different VAR2CSA domains and variants produced in prokaryotic and eukaryotic expression systems. Antisera were initially tested against laboratory lines of maternal parasites, and the most promising reagents were evaluated in the field against fresh placental parasite samples. Recombinant proteins expressed in Escherichia coli elicited antibody levels similar to those expressed in eukaryotic systems, as did the two allelic forms of the DBL4 and DBL5 domains. The procedures developed for this head-to-head comparison will be useful for future evaluation and down-selection of malaria vaccine immunogens.
Collapse
|
7
|
Jiang N, Meng L, Lu HJ, Kang W, Peng S, Pan WQ, Yin JG, Chen QJ. Analysis of var genes cloned from a Plasmodium falciparum isolate in China. ASIAN PAC J TROP MED 2012; 5:85-90. [PMID: 22221747 DOI: 10.1016/s1995-7645(12)60001-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 12/15/2011] [Accepted: 01/15/2012] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE To analyse the var gene repertoire and characterise the chondroitin sulphate A (CSA)-binding activity of the Duffy-binding like (DBL) domains encoded by the var2csa gene of a Plasmodium falciparum (P. falciparum) isolate in Hainan Province, China. METHODS The sequences of var DBL1 regions were PCR-amplified, sequenced and the sequence characteristics was bioinformatically analysed. Recombinant proteins encoded by the var2csa genes were expressed and purified. The binding activities of the recombinant proteins to CSA receptor was detected by ELISA assays. RESULTS Fifty six unique DBL α sequences were obtained, and the sequences represented similar diversity to the var genes of the genome parasite 3D7. There are two var2csa genes in the P. falciparum isolated from Hainan Province. Unlike in other falciparum parasites such as HB3, the two var2csa genes are more diverged. The receptor-binding capacity of DBL-5ε and DBL-6ε domains of HN var2CSA was studied. CONCLUSIONS This work represented the diversity of var genes of a P. falciparum isolate in China.
Collapse
Affiliation(s)
- Ning Jiang
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Var2CSA minimal CSA binding region is located within the N-terminal region. PLoS One 2011; 6:e20270. [PMID: 21625526 PMCID: PMC3098292 DOI: 10.1371/journal.pone.0020270] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Accepted: 04/17/2011] [Indexed: 11/24/2022] Open
Abstract
Var2CSA, a key molecule linked with pregnancy-associated malaria (PAM), causes sequestration of Plasmodium falciparum infected erythrocytes (PEs) in the placenta by adhesion to chondroitin sulfate A (CSA). Var2CSA possesses a 300 kDa extracellular region composed of six Duffy-binding like (DBL) domains and a cysteine-rich interdomain region (CIDRpam) module. Although initial studies implicated several individual var2CSA DBL domains as important for adhesion of PEs to CSA, new studies revealed that these individual domains lack both the affinity and specificity displayed by the full-length extracellular region. Indeed, recent evidence suggests the presence of a single CSA-binding site formed by a higher-order domain organization rather than several independent binding sites located on the different domains. Here, we search for the minimal binding region within var2CSA that maintains high affinity and specificity for CSA binding, a characteristic feature of the full-length extracellular region. Accordingly, truncated recombinant var2CSA proteins comprising different domain combinations were expressed and their binding characteristics assessed against different sulfated glycosaminoglycans (GAGs). Our results indicate that the smallest region within var2CSA with similar binding properties to those of the full-length var2CSA is DBL1X-3X. We also demonstrate that inhibitory antibodies raised in rabbit against the full-length DBL1X-6ε target principally DBL3X and, to a lesser extent, DBL5ε. Taken together, our results indicate that efforts should focus on the DBL1X-3X region for developing vaccine and therapeutic strategies aimed at combating PAM.
Collapse
|
9
|
Gnidehou S, Jessen L, Gangnard S, Ermont C, Triqui C, Quiviger M, Guitard J, Lund O, Deloron P, Ndam NT. Insight into antigenic diversity of VAR2CSA-DBL5ε domain from multiple Plasmodium falciparum placental isolates. PLoS One 2010; 5. [PMID: 20957045 PMCID: PMC2948511 DOI: 10.1371/journal.pone.0013105] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Accepted: 07/29/2010] [Indexed: 11/18/2022] Open
Abstract
Background Protection against pregnancy associated malaria (PAM) is associated with high levels of anti-VAR2CSA antibodies. This protection is obtained by the parity dependent acquisition of anti-VAR2CSA antibodies. Distinct parity-associated molecular signatures have been identified in VAR2CSA domains. These two observations combined point to the importance of identifying VAR2CSA sequence variation, which facilitate parasitic evasion or subversion of host immune response. Highly conserved domains of VAR2CSA such as DBL5ε are likely to contain conserved epitopes, and therefore do constitute attractive targets for vaccine development. Methodology/Principal Findings VAR2CSA DBL5ε-domain sequences obtained from cDNA of 40 placental isolates were analysed by a combination of experimental and in silico methods. Competition ELISA assays on two DBL5ε variants, using plasma samples from women from two different areas and specific mice hyperimmune plasma, indicated that DBL5ε possess conserved and cross-reactive B cell epitopes. Peptide ELISA identified conserved areas that are recognised by naturally acquired antibodies. Specific antibodies against these peptides labelled the native proteins on the surface of placental parasites. Despite high DBL5ε sequence homology among parasite isolates, sequence analyses identified motifs in DBL5ε that discriminate parasites according to donor's parity. Moreover, recombinant proteins of two VAR2CSA DBL5ε variants displayed diverse recognition patterns by plasma from malaria-exposed women, and diverse proteoglycan binding abilities. Conclusions/Significance This study provides insights into conserved and exposed B cell epitopes in DBL5ε that might be a focus for cross reactivity. The importance of sequence variation in VAR2CSA as a critical challenge for vaccine development is highlighted. VAR2CSA conformation seems to be essential to its functionality. Therefore, identification of sequence variation sites in distinct locations within VAR2CSA, affecting antigenicity and/or binding properties, is critical to the effort of developing an efficient VAR2CSA-based vaccine. Motifs associated with parasite segregation according to parity constitute one such site.
Collapse
Affiliation(s)
- Sédami Gnidehou
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Université Paris Descartes, Paris, France
- * E-mail: (SG); (NTN)
| | - Leon Jessen
- Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark
| | - Stéphane Gangnard
- Unité d'Immunologie Structurale, Institut Pasteur, CNRS URA2185, Paris, France
| | - Caroline Ermont
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Université Paris Descartes, Paris, France
| | - Choukri Triqui
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Université Paris Descartes, Paris, France
| | - Mickael Quiviger
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Université Paris Descartes, Paris, France
| | - Juliette Guitard
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Université Paris Descartes, Paris, France
| | - Ole Lund
- Department of Systems Biology, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark
| | - Philippe Deloron
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Université Paris Descartes, Paris, France
| | - Nicaise Tuikue Ndam
- Institut de Recherche pour le Développement, IRD UMR 216, Mère et Enfant Face aux Infections Tropicales, Paris, France
- Institut des Sciences Biomédicale et Appliquées, Cotonou, Benin
- * E-mail: (SG); (NTN)
| |
Collapse
|