Analysis of Variation in PF83, an Erythrocytic Merozoite Vaccine CandidateAntigen of Plasmodium falciparum

摘要

We have previously reported the identification of a 66-kDa Plasmodium knowlesilate-stage schizont protein (PK66) by monoclonal antibodies that inhibit in vitro multiplication of P. knowlesi. These antibodies are effective as Fab fragments, and are effective against free merozoites (Thomas, unpublished observation) suggesting that PK66 has a role in the invasion of erythrocytes. PK66 is processed to 44/42-kDa components at the time of merozoite release, and these smaller fragments appear to be associated with the merozoite surface. When isolated in native, but not in denatured form, PK66 induced inhibitory antibody in rabbits and induced protective antibody in rhesus monkeys, apparently in a synergistic response with other parasite antigens. An 83-kDa precursor molecule of Plasmodium falciparum, that we call PF83, is synthesized by late-stage schizont infected erythrocytes, is processed to a 66-kDa component at or around the time of merozoite release, and by virtue of cross-reactivity with rabbit polyclonal anti-PK66, was identified as the P. falciparum analogue of PK66 (results presented at the Third International Congress on Malaria and Babesiosis, Annecy, France, 1987).