ACQUIRED ANTIBODY-LEVELS TO PLASMODIUM-FALCIPARUM MEROZOITE SURFACE-ANTIGEN-1 IN RESIDENTS OF A HIGHLY ENDEMIC AREA OF PAPUA-NEW-GUINEA

The prevalence and concentration of antibodies to a yeast-expressed N- terminal region (195A) and a baculovirus-expressed C-terminal region ( BVp42) of merozoite surface antigen 1 (MSA-1) were measured during a c ross-sectional survey in the Wosera area of East Sepik Province, Papua New Guinea, in order to obtain baseline data on naturally acquired an tibody response to this antigen in preparation for a vaccine trial. Ov erall, the seropositivity rate was 78% for 195A and 91% for BVp42. Alt hough antibody prevalence to both molecules increased with age, higher antibody prevalence rates were observed for BVp42 in all age groups s tudied. In children, significant positive associations were found betw een parasite prevalence and antibody prevalence for both regions of MS A-1 and between spleen rates and anti-BVp42 antibody prevalence. Conce ntration of antibody against both regions increased significantly with age, but: was always higher for BVp42. In children, antibody levels t o both regions of MSA-1 were significantly higher in those infected (s ymptomatic and asymptomatic), while in adults no significant differenc e in antibody concentration was observed between those infected and th ose uninfected. However, enlarged spleens were associated with higher antibody concentration to both regions of MSA-1 in both children and a dults. The C-terminal of MSA-1 appeared to be more recognized than the N-terminal, in terms of both antibody prevalence and concentration.