[Soluble antigens of intra-erythrocyte stages of Plasmodium falciparum: diagnostic and vaccinal value].

A wide variety of soluble antigens also called exoantigens or excretory-secretory antigens are released by asexual blood stages of P. falciparum at the time of schizont burst and subsequent merozoite invasion. At present, most of these soluble malarial proteins have been purified and have had their genes cloned; the primary sequence displays considerable polymorphism upon tandem repeats. However, its function and the relevance of the polymorphism for the induction of host immune response, predominantly IgM and T-cell-independent type, has yet to be determined. The potential of P. falciparum exoantigens as immunodiagnostic tools has been the focus of numerous studies. Enzyme immunoassays or radioimmunoassays for the detection of malarial antigens in blood of suspected peoples have been reported. Their development requires increasing both specificity and sensitivity. Recently, some P. falciparum exoantigens have been proposed as candidates for inclusion in an anti-disease vaccine which induces a clinical but not parasiticidal immunity against malaria. There is much interest in this concept and their efficiency remains to be confirmed, as new strategies are needed in the prevention of malaria.