Identification of a continuous and cross-reacting epitope for Plasmodium falciparum transmission-blocking immunity.

Identification of continuous epitopes in the target antigens of Plasmodium falciparum transmission-blocking antibodies is likely to facilitate the production of a subunit peptide vaccine. Two such epitopes shared among several sexual-stage antigens were identified with murine monoclonal antibodies. An epitope recognized by four monoclonal antibodies capable of blocking infectivity of gametocytes in the mosquitoes is shared among three antigens (230, 48/45 doublet, and 27 kDa). These antigens are synthesized at different times during the development and maturation of gametocytes, and the blocking epitope appears conserved among parasites from diverse geographical locations. Immune response against such a unique epitope (continuous, cross-reacting, and conserved) is likely to be boosted by natural infection. The 27-kDa protein is reported here as a target of malaria transmission-blocking monoclonal antibodies, and the cross-reacting epitope represents an attractive candidate for a transmission-blocking vaccine.