Wild isolates of Plasmodium falciparum show extensive polymorphism in T cell epitopes of the circumsporozoite protein.

Variation in the immunodominant T cell epitopes Th2R and Th3R of the Plasmodium falciparum circumsporozoite protein has been analysed from Gambian clinical isolates using the polymerase chain reaction. The degree of polymorphism in these epitopes is more extensive than that found in several geographically diverse laboratory isolates. These findings strongly suggest that it will not be feasible to include all variants in a polyvalent subunit sporozoite vaccine.