RESUMO
RESA-IFA assays were conducted using 63 adult sera from 7 different malarious areas against 7 different strains of Plasmodium falciparum, and 28 children's sera against 3 different parasite strains. Generally, where immunity to malaria was high, there was little or no antigenic diversity among the different strains examined. However, where sera were collected from semi-immunes, or from children, some variation in the RESA-IFA endpoint titers was discernible. Correlation between antibody titers determined by RESA-IFA and in vitro parasite invasion inhibition was not complete. Sera having high RESA-IFA titers were predictably inhibitory; however, many sera having low RESA-IFA titers were as inhibitory as sera having high titers, indicating that antibodies with specificities different from the RESA may be as important, or more important, to clinical immunity to blood-stage infections.