IDENTIFICATION OF A SUBPOPULATION OF IMMUNE NIGERIAN ADULT VOLUNTEERSBY ANTIBODIES TO THE CIRCUMSPOROZOITE PROTEIN OF PLASMODIUM-FALCIPARUM

Collections of human sera from malaria-endemic areas would be valuable for identifying and characterizing antigens as malaria vaccine candid ates if the contributing serum donors' ability to resist infection wer e fully characterized. We prepared such a serum collection from 26 app arently immune Nigerian adults who failed to develop patent parasitemi a for at least 20 weeks following a documented increase in antibodies to the circumsporozoite protein (CSP) from Plasmodium falciparum. Volu nteers were evaluated five times per week for malaria symptoms and bim onthly for parasites by examining thick blood smears. The incidence ra te over 13 months for the cohort was 42% (47 malaria-confirmed volunte ers) and the risk of infection was 1.3 infections/year. Responses to C SP did not correlate with protection. Because antibody responses to an tigens other than CSP may be associated with protection, the sera from these immune individuals may be useful for identifying and characteri zing other potential malaria vaccine candidates.