Antigenic characterization of Plasmodium vivax with monoclonal antibodies.

Monoclonal antibodies were produced against Plasmodium vivax obtained from patients living in southeastern Mexico, where P. vivax malaria is endemic. Nine hybridomas specific for this parasite were obtained. By an indirect immunofluorescence assay, seven antibodies were found to react with epitopes present in the cytoplasm of the infected erythrocyte and two with the parasite itself. By immunoblotting, five monoclonal antibodies reacted with a 17-kD protein band, three with an 85-kD band, and two with one of 45 kD. By immunogold electron microscopy, two antibodies that reacted with the cytoplasm of infected erythrocytes by immunofluorescence also labeled cytoplasmic clefts, and one, in addition, recognized caveola-vesicle complexes and the parasite matrix. These results demonstrate the value of monoclonal antibodies in identifying P. vivax antigens and disclosing their subcellular distribution.