HUMORAL RESPONSE TO DEFINED PLASMODIUM-FALCIPARUM ANTIGENS IN CEREBRAL AND UNCOMPLICATED MALARIA AND THEIR RELATIONSHIP TO PARASITE GENOTYPE

The prevalence and concentration of IgG antibodies to defined Plasmodi um falciparum antigens were assessed in serum samples of 97 samples of children with cerebral malaria and 146 children with uncomplicated ma laria. The antigens used included the schizont extract, ring-infected erythrocyte surface antigen, the C-terminal region of merozoite surfac e antigen-1 (MSA-1) (BVp42), and three recombinant proteins of MSA-2 ( FC27, 3D7, and d3D7). Parasite isolates from 24 children with cerebral malaria and 22 children with uncomplicated malaria were genotyped for MSA-1 and MSA-2. The distribution of parasite genotypes belonging to the different allelic families was similar in both the cerebral and un complicated malaria groups. The were higher antibody levels to antigen s derived from the infecting parasite genotype than to heterologous ge notypes, but this difference was only statistically significant for an tibody against the d3D7 antigen among children infected with the 3D7 p arasite genotype (mean log = 4.72 versus 3.45 antibody units [AU]; P = 0.029). Antibodies against parasites of the 3D7 genotype are associat ed with a better prognosis among children with cerebral malaria partly because these children are more likely to be infected with parasites of this genotype rather than the FC27 genotype, which appears to be mo re virulent.