How specific is the immune response to malaria in adults living in endemic areas?

Abstract

It is documented that people living in malaria endemic areas acquire immunity against malaria after repeated infections. Studies involving passive transfer of IgG from immune adults to the nonimmune subjects have shown that circulating antibodies play an important role, and that immune adults possess protective antibodies, which susceptible malaria patients do not. Through a differential immunoscreen, we have identified several novel cDNA clones, which react exclusively and yet extensively with immune sera samples. Specific antisera raised against the immunoclones inhibit the growth of parasites in culture. The clones studied so far turn out to be novel conserved Plasmodium genes. In order to study the response of sera of adults from malaria endemic areas of India and Africa to these immunogens, we carried out ELISA assays using these immunopeptides, other P. falciparum specific antigens, peptides, antigens from other infections such as mycobacterial infections and other proteins such as BSA. Children from the same areas and normal healthy urban people showed very little activity to each of these categories. A large percentage of adults from endemic areas responded positively to all the malarial immunogens tested. However, the same persons also showed high response to other antigens and proteins as well. The implications of these results are reported in this paper.