Analysis of Antibodies to Newly Described Plasmodium falciparum Merozoite Antigens Supports MSPDBL2 as a Predicted Target of Naturally Acquired Immunity

Prospective studies continue to identify malaria parasite genes with particular patterns of polymorphism which indicate they may be under immune selection, and the encoded proteins require investigation. Sixteen new recombinant protein reagents were designed to characterize three such polymorphic proteins expressed in Plasmodium falciparum schizonts and merozoites: MSPDBL1 (also termed MSP3.4) and MSPDBL2 (MSP3.8), which possess Duffy binding-like (DBL) domains, and SURFIN4.2, encoded by a member of the surface-associated interspersed ( surf ) multigene family. After testing the antigenicities of these reagents by murine immunization and parasite immunofluorescence, we analyzed naturally acquired antibody responses to the antigens in two cohorts in coastal Kenya in which the parasite was endemic (Chonyi [ n = 497] and Ngerenya [ n = 461]). As expected, the prevalence and levels of serum antibodies increased with age. We then investigated correlations with subsequent risk of clinical malaria among children