Analysis of Variation in PF83, an Erythrocytic Merozoite Vaccine Candidate Antigen of Plasmodium falciparum
WALTER REED ARMY INST OF RESEARCH WASHINGTON DC DEPT OF IMMUNOLOGY
Pagination or Media Count:
We have previously reported the identification of a 66-kDa Plasmodium knowlesi late-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 These antibodies are effective as Fab fragments, and are effective against free merozoites Thomas, unpublished observation suggesting that PK66 has a role in the invasion of erythrocytes.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 4442-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 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.