PLASMODIUM-FALCIPARUM - ALTERED EXPRESSION OF ERYTHROCYTE MEMBRANE-ASSOCIATED ANTIGENS DURING ANTIGENIC VARIATION

Plasmodium falciparum: Altered expression of erythrocyte membrane-asso ciated antigens during antigenic variation. Experimental Parasitology 85, 135-148. The O and R antigenic variants of the Plasmodium falcipar um Palo Alto strain present differences in the morphology of the infec ted red blood cell membrane, in their adhesion properties, surface imm unofluorescence, and agglutination specificities and importantly, indu ce a variant-specific protection after a primary infection in Saimiri sciureus monkeys. To identify potential targets of variant-specific im munity, we have compared the antigenic makeup of both variants by immu noblot. O-specific monkey sera generated similar profiles on both para site types, while R-specific sera showed a consistent difference on a high-molecular-mass undefined antigen. Distinct antibody specificities were eluted from the surface of O- or R-infected erythrocytes, genera ting variant-specific agglutination, surface immunofluorescence, and i mmunoblot profiles. An antiserum raised to Pf60.1, predicted to cross- react with the cytoplasmic domain of PfEMP1, reacted with specific, SD S-soluble antigens in both variants. Antigens associated with the memb rane of the infected red blood cells were further investigated using s everal specific antisera. The 85-kDa HRP1 gene product was more abunda nt in O than in R parasites, while the reverse was observed for the Pf EMP3 protein. These data indicate that O and R parasites differ in the expression of several antigens associated with the membrane of the in fected red blood cell. (C) 1997 Academic Press.