USE OF A RECOMBINANT BACULOVIRUS PRODUCT TO MEASURE NATURALLY-ACQUIRED HUMAN-ANTIBODIES TO DISULFIDE-CONSTRAINED EPITOPES ON THE PLASMODIUM-FALCIPARUM MEROZOITE SURFACE PROTEIN-1 (MSP1)

An enzyme-linked immunosorbent assay (ELISA) has been developed to mea sure antibody levels in human sera to a candidate vaccine antigen, mer ozoite surface protein-1 (MSP1), of the malaria parasite Plasmodium fa lciparum. To ensure the detection of antibodies reactive with importan t conformational epitopes, antigens used in the ELISA were obtained fr om either in vitro parasite cultures, or from a baculovirus expression system in which correct folding of recombinant MSP1-derived polypepti des has been previously demonstrated. The specificity of the ELISA was confirmed using a novel antibody affinity select method. The assay wa s used to investigate the pattern of acquisition of anti-MSP1 antibodi es in a cross-sectional survey of 387 3-8 year old residents of a mala ria endemic area of The Gambia. A significant positive correlation bet ween anti-MSP1 antibody levels and age was evident, though individual responses to two antigens corresponding to two distinct domains of the MSP1 varied widely.