Human antibody response to Plasmodium falciparum merozoite surface protein 2 is serogroup specific and predominantly of the immunoglobulin G3 subclass.

MSP2 is a merozoite surface protein of Plasmodium falciparum and, as such, is a potential component of a malaria vaccine. In this study, we have used a panel of recombinant MSP2 antigens in enzyme-linked immunosorbent assays to investigate the recognition of MSP2 by antibodies from malaria-immune human serum. These recombinant antigens include full-length proteins of serogroups A and B and fragments representing the conserved, group-specific, or repeat regions of each serogroup. Ninety-five percent of the serum samples tested contained MSP2-specific antibodies: 81% of serum samples tested responded to serogroup A, and 86% responded to serogroup B. The antibody response is directed almost exclusively towards dimorphic and polymorphic regions of MSP2; the conserved regions are rarely recognized, and antibodies to serogroups A and B do not cross-react. Interestingly, the antibody response is predominately of the cytophilic and complement-fixing subclass immunoglobulin G3.