Human antibody response to the major merozoite surface antigen of Plasmodium falciparum is strain specific and short-lived

The precursor of the major merozoite antigen of Plasmodium falciparum, gp190, is considered a candidate for inclusion in a malaria vaccine. This protein, which consists of conserved, dimorphic, and polymorphic sequences, is very immunogenic in humans. In a longitudinal study carried out with 94 inhabitants of a rural community in Mali, West Africa, we show that in this endemic area naturally acquired gp190-specific antibodies are predominantly directed against the dimorphic parts of one of the two main alleles of gp190. The presence of antibodies against these dimorphic regions correlates with the prevalence of the corresponding antigen in the infecting parasite population. Moreover, qualitative as well as quantitative differences were found in the time course of the humoral immune response to the dimorphic regions in adults and children, who differ in their susceptibility to malaria infection.