Acquisition of antibodies to variant antigens on the surface of Plasmodium falciparum-infected erythrocytes during pregnancy

Pregnancy-associated malaria is characterized by Plasmodium falciparum adherence to chondroitin sulfate A (CSA) in placenta, through a particular variant surface antigen (VSA). VSACSA-specific IgG are involved in protection against placental malaria. In order to assess the relationship between VSACSA-specific antibody responses and parity as well as protection against placental malaria, the occurrence of P. falciparum infection was assessed in 306 pregnant women from a low malaria transmission area of Senegal. Anti-VSACSA antibodies against three placental parasite isolates were measured by flow cytometry, at enrollment and delivery. Placental infection prevalence rates were highest in primigravidae, but no clear decreasing trend was observed from the second pregnancy onwards. Anti-VSACSA antibody prevalence rates increased with parity. Both anti-VSACSA antibody prevalence rates and levels increased during pregnancy only in women infected with P. falciparum. Although a single or a very limited number of P. falciparum infections were able to induce an anti-VSACSA antibody response, the level or the quality of this response did not appear to confer protection against placental malaria infection.