PLASMODIUM-FALCIPARUM - THE PF332 ANTIGEN IS SECRETED FROM THE PARASITE BY A BREFELDIN A-DEPENDENT PATHWAY AND IS TRANSLOCATED TO THE ERYTHROCYTE-MEMBRANE VIA THE MAURERS CLEFTS

The transport of the megadalton protein Pf332 was studied during the a sexual bloodstage development of Plasmodium falciparum. Four mouse mon oclonal antibodies, produced against a recombinant polypeptide derived from the Pf332 protein, were used to analyze the kinetics of synthesi s, the subcellular location, and transport of this giant molecule to t he erythrocyte membrane. After parasite invasion of a red brood cell, the Pf332 antigen is first detected in young trophozoites at the paras itophorous vacuole membrane or in the cytoplasm of the erythrocyte as large vesicle-like structures. The number of Vesicles increases during maturation of the parasite and thus forms a rim-like immunofluorescen ce pattern between the erythrocyte membrane and the parasitophorous va cuole at very late stages. The various anti-Pf332 antibodies react wit h the surface of erythrocytes infected with very mature parasites (seg menter stage 42-46 hr postinvasion). Immunoelectron microscopic analys is shows that the Pf332 antigen is transported in association with Mau rer's clefts in the cytoplasm of the erythrocyte. This transport could be completely blocked by Brefeldin A, resulting in the accumulation o f the antigen within the parasite. These data strongly suggest that th e Pf332 antigen is exported to the erythrocyte cytoplasm via the class ical Golgi secretory pathway. (C) 1994 Academic Press, Inc.