Acquisition and decay of antibodies to pregnancy-associated variant antigens on the surface of Plasmodium falciparum-infected erythrocytes that protect against placental parasitemia

Otherwise clinically immune women in areas endemic for malaria are highly s usceptible to Plasmodium falciparum malaria during their first pregnancy. P regnancy-associated malaria (PAM) is characterized by placental accumulatio n of infected erythrocytes that adhere to chondroitin sulfate A (CSA). Susc eptibility to PAM decreases with increasing parity, apparently due to acqui sition of antibodies directed against the variant surface antigens (VSAs) t hat mediate the adhesion to CSA (VSA(CSA)). This study found that levels of VSA(CSA)-specific antibodies depend on endemicity, that anti-VSA(CSA) IgG is acquired during gestation week 20, and that plasma levels of the antibod ies decline during the postpartum period. There is evidence that VSA(CSA)-s pecific antibodies are linked to placental infection and that high antibody levels contribute to the control of placental infection by inhibiting para site adhesion to CSA. Data suggest that VSA(CSA) is a target for vaccinatio n against PAM.