Antibodies to variant surface antigens of plasmodium falciparum-infected erythrocytes are associated with protection from treatment failure and the development of anemia in pregnancy

Abstract

Background. In pregnancy-associated malaria (PAM), Plasmodium falciparum-infected erythrocytes (IEs) express variant surface antigens (VSA-PAM) that evade existing immunity and mediate placental sequestration. Antibodies to VSA-PAM develop with gravidity and block placental adhesion or opsonize IEs for phagocytic clearance, helping to prevent maternal anemia and low birth weight in infants. Methods. Using serum samples from 141 pregnant Malawian women with parasitemia enrolled in a randomized trial of antimalarials and VSA-PAM-expressing CS2 IEs, we quantified levels of immunoglobulin (Ig) G to VSAPAM by flow cytometry and levels of opsonizing antibodies by measuring uptake of IEs by THP1 pr..