IMMUNOGENICITY AND ANTIGENICITY OF A PLASMODIUM-FALCIPARUM PROTEIN-FRACTION (90-110 KDA) ABLE TO PROTECT SQUIRREL-MONKEYS AGAINST ASEXUAL BLOOD STAGES

A monkey vaccination trial using a Plasmodium falciparum protein fract ion containing antigens of 90-110 kDa is reported. The fraction was ob tained by electroelution from preparative polyacrylamide gels. Three m onkeys out of five resisted a heavy challenge dose of highly virulent parasites. Using specific antisera, several components of the fraction were identified, namely heat shock protein 90 (hsp90), Ag44/RhopH3, A BRA, 96tR/GBP130 and Pf96 protease. The fraction did not contain KAHRP , nor the SERF antigen. The antibody response of the monkeys was studi ed on these individual antigens purified by preparative immunoprecipit ation. Surprisingly, hsp90 was found in the immunoprecipitates obtaine d with SERF antisera. Interestingly, the response to hsp90 correlated with protection, high antibody titres being found only in the protecte d monkeys. In contrast, no correlation with protection could be found for the response to the other antigens.