Analysis of human antibodies to erythrocyte binding antigen 175 of Plasmodium falciparum

Invasion of human erythrocytes by Plasmodium falciparum merozoites is a mul tistep process, For many strains of the parasite, part of this process requ ires that the erythrocyte binding antigen 175 (EBA-175) of the merozoite bi nds to sialic acid residues of glycophorin A on the erythrocyte surface, a receptor-ligand interaction which represents a potential target for inhibit ion by antibodies. This study characterizes the reactivity of naturally acq uired human antibodies with four recombinant proteins representing parts of EBA-175 (region II, regions III to V, and the dimorphic C and F segment re gion) in populations in which the organism is endemic, Serum immunoglobulin G (IgG) recognizing the recombinant proteins is predominantly of the IgG1 and IgG3 subclasses, and its prevalence increases with age. In a large popu lation study in The Gambia, serum positivity for IgG or IgG1 and IgG3 subcl ass antibodies to each of the EBA-175 recombinant antigens was not signific antly associated with subsequent protection from clinical malaria. However, there was a trend indicating that individuals with high Levels of IgG to r egion II may have some protection.