Immunogold electron microscopy for ultrastructural localization of HRPII in the gametocyte. Gametocytes were identified by a corset of microtubules (M) and a three-membrane pellicular complex (P). Arrowheads mark gold particles. (B) Gametocyte labeling with secondary gold-conjugated antibody only. Bar, 500 nm.

When the gametocyte matures, the distribution of HRPII to the host cell cytoplasm is limited and may be affected by the formation of the trilaminate membrane in stage IIA gametocytes and certainly a general reduction in protein level. A reduction in HRPII trafficking correlates with cessation of hemoglobin breakdown and subsequent heme processing as gametocytes mature. Authors speculate that HRPII in the infected RBC of late gametocytes is residual protein from synthesis, translocation, and function in earlier stages.

Hayward RE, Sullivan DJ, Day KP. Plasmodium falciparum: histidine-rich protein II is expressed during gametocyte development. Exp Parasitol. 2000 96:139-46. A