PATTERNS OF ANTIBODY-LEVELS TO THE 96-TR RECOMBINANT PROTEIN OF PLASMODIUM-FALCIPARUM IN CHILDREN OVER A 6-MONTH PERIOD

Several Plasmodium falciparum asexual stage antigens have been reporte d as possible candidate antigens for vaccines against malaria. One suc h is the 96-kDa antigen. We used the 96 tR recombinant protein to dete rmine the levels of antibodies to this protein over a 6-mo period in c hildren 4 mo to 15 yr old, who make up the population at risk in Camer oon. The mean enzyme-linked immunosorbent assay (ELISA) on 83 children at the start of the study in June was 0.270, with 13% of these childr en having ELISA values considered to be positive (greater than or equa l to 0.36). In the follow-up study in early December, the mean ELISA w as 0.320 with 20% of the children having positive values. In the perio d between June and December, 85% of the children who returned for foll ow-up had had I or more attacks of malaria. The mean ELISA values of t his latter group had increased from 0.235 in June to 0.318 in December , with 6% of the children in June having positive values compared with 18% in December. These findings reinforce our evidence from a previou s study that reactivity to the 96-kDa antigen is related to adequate e xposure or repeated infection.