Membrane-associated antigens of blood stages of Plasmodium, brasilianum, a quartan malaria parasite.

The localization of Plasmodium brasilianum-derived antigens in short and long clefts within the cytoplasm of infected erythrocytes and in association with knobs of the host cell membrane was demonstrated by immunoelectron microscopy with monoclonal antibodies. Our results document that malaria-induced short and long clefts, previously distinguishable only by morphology, differ also in antigenic composition. Another parasite-derived antigen was found to be associated with the parasitophorous vacuole space in schizonts. In segmenters, this antigen was present in large amounts between merozoites and in the cytoplasm of infected cells. These antigens were characterized by biosynthetic labeling and gel electrophoresis.