title: Differential induction of functional IgG using the Plasmodium falciparum placental malaria vaccine candidate VAR2CSA.
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.
  
  
  RESULTS
  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
  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.
authors.affiliation: Department of International Health, Immunology and Microbiology, University of Copenhagen, Centre for Medical Parasitology, Copenhagen, Denmark.
authors.forename: Vera V
authors.initials: VV
authors.lastname: Pinto
authors.forename: Sisse B
authors.initials: SB
authors.lastname: Ditlev
authors.forename: Kamilla E
authors.initials: KE
authors.lastname: Jensen
authors.forename: Mafalda
authors.initials: M
authors.lastname: Resende
authors.forename: Madeleine
authors.initials: M
authors.lastname: Dahlbäck
authors.forename: Gorm
authors.initials: G
authors.lastname: Andersen
authors.forename: Pernille
authors.initials: P
authors.lastname: Andersen
authors.forename: Thor G
authors.initials: TG
authors.lastname: Theander
authors.forename: Ali
authors.initials: A
authors.lastname: Salanti
authors.forename: Morten A
authors.initials: MA
authors.lastname: Nielsen
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000917:Antibody Formation / Q000276:immunology; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D004912:Erythrocytes / Q000469:parasitology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D017780:Malaria Vaccines / Q000276:immunology*; D016778:Malaria, Falciparum / Q000276:immunology* / Q000469:parasitology; D051379:Mice; D010920:Placenta / Q000276:immunology* / Q000469:parasitology*; D010963:Plasmodium falciparum / Q000276:immunology*; D011247:Pregnancy; D040081:Protein Array Analysis; D017434:Protein Structure, Tertiary; D011817:Rabbits; D051381:Rats; D011994:Recombinant Proteins / Q000276:immunology; D013045:Species Specificity
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes; D007074:Immunoglobulin G; D017780:Malaria Vaccines; D011994:Recombinant Proteins; C512601:VAR2CSA protein, Plasmodium falciparum