Plasmodium vivax and Plasmodium chabaudi: Intraerythrocytic traffic of antigenically homologous proteins involves a brefeldin A-sensitive secretory pathway

We have used a monoclonal antibody (mAb 7C5B71) raised against the erythroc ytic stages of Plasmodium vivax to identify a 148-kDa P. vivax protein anti gen (Pv-148) which crossreacts with an antigenically homologous 190-kDa pro tein of P. chabaudi (Pc-190). During parasite intraerythrocytic development Pv-148 and Pc-190 are exported into the host cell cytosol and become locat ed in the surface membrane of the infected erythrocyte. Immunofluorescence confocal microscopy and immunoelectron microscopy studies showed that both Pv-148 and Pc-190 are released from the parasite and exported to the host c ell cytoplasm in association with tubovesicular membrane (TVM) structures. Fluorescent in vivo labelling of P. chabaudi with Bodipy(R)-ceramide follow ed by immunofluorescence staining with the mAb supported the association of antigenically homologous Pc-190 with TVM structures. In the presence of br efeldin A (BFA), secretion of antigenically homologous Pc-190 into the host cell cytoplasm was inhibited and the antigen remained in the parasite cyto plasm. BFA also arrested the maturation of the parasite. Taken together the se results suggest that Pv-148 and Pc-190 are related parasite proteins tha t are transported into the host cell through a BFA-sensitive secretory path way.