Serological cross-reaction between high molecular weight proteins synthesized in blood schizonts of Plasmodium yoelii, Plasmodium chabaudi and Plasmodium falciparum.

A 230 000 molecular weight (MW) Plasmodium yoelii protein, a 250 000 MW P. chabaudi protein and a 195 000 MW P. falciparum protein, identified using monoclonal antibodies, have similar characteristics, and have been implicated as protective antigens. In this study the serological relationship between these proteins was investigated by Western transfer analysis. The monoclonal antibodies specific for each of the high molecular weight proteins did not cross-react with antigens of the other two parasites, but a polyvalent mouse serum raised against the purified 230 000 MW P. yoelii protein cross-reacted with the high molecular weight proteins of P. chabaudi and P. falciparum and also with the fragments derived from these proteins. This result indicates that these proteins belong to the same class of malaria parasite antigen.