Plasmodium falciparum merozoite surface protein 3 is a target of allele-specific immunity and alleles are maintained by natural selection.

Background: Plasmodium falciparum merozoite surface protein (MSP) 3 is an asexual blood-stage malaria vaccine candidate antigen. Sequence polymorphisms divide alleles into 2 major types, but the adaptive and immunological significance of the types has not been defined.

Methods: One hundred one msp3 allele sequences were sampled from 2 populations living in areas where malaria is endemic and were analyzed for evidence of natural selection.