ANALYSIS OF THE HUMAN-ANTIBODY RESPONSE TO THROMBOSPONDIN-RELATED ANONYMOUS PROTEIN OF PLASMODIUM-FALCIPARUM

Thrombospondin-related anonymous protein (TRAP) of the malaria parasit e Plasmodium falciparum shares two sequence motifs with other proteins which possess adhesive properties. Recently, findings indicate that T RAP is an antigen which contributes to antisporozoite immunity. We hav e cloned and expressed the TRAP coding sequences in Escherichia coli t o investigate the human humoral immune response against this protein i n a region of malaria endemicity of West Africa characterized by a sea sonal transmission. Our results show that antibodies against TRAP are present in infected individuals. The anti-TRAP antibodies were analyze d in both a longitudinal and a prospective study. The longitudinal ana lysis shows seasonal fluctuations of the levels of specific antibodies as well as age-dependent quantitative differences. The immune respons e is long-lived in most of the adults and some of the older children b ut short-lived in young children. More importantly, the prospective an alysis suggests that the presence of anti-TRAP antibodies in older chi ldren before the beginning of malaria transmission correlates with the subsequent control of parasite densities.