Clinical immunity to Plasmodium falciparum malaria is associated with serum antibodies to the 19-kDa C-terminal fragment of the merozoite surface antigen, PfMSP-1.

The development of an effective malaria vaccine depends upon identification of antigens that are targets of protective immune responses. An immunoepidemiologic approach has been used to investigate the relationship between antibody responses to a defined region of the major merozoite surface protein of Plasmodium falciparum (PfMSP-1 19) and resistance to clinical malaria in 2 populations of children from West Africa. After allowing for the confounding effects of age, antibodies to PfMSP-1 19 were shown the provide 40% protection against clinical malaria in children in Sierra Leone. In Gambian children, antibodies to one of the epidermal growth factor-like motifs of PfMSP-1 19 were strongly associated with resistance to both clinical malaria and high levels of parasitemia.