Staining of Malarial Parasites by the Fluorescent Antibody Technic

Abstract

Malarial organisms, Plasmodium cynomolgi bastianellii and P. gallinaceum, were studied by the fluorescent antibody technic to determine: (1) whether serum from convalescent infected monkeys could be labeled with fluorescein isothiocyanate (FIC) to stain the erythrocytic stage of the parasite, and (2) if antibodies could be produced against the sporozoite stage of the organism and labeled with FIC to stain the erythrocytic form of the parasite. Serums were collected from Rhesus monkeys which spontaneously recovered from several experimental infections with P. cynomolgi bastianellii. Gamma-globulin precipitated 1/3 sat. (NH4 2SO4 was conjugated with FIC in the usual manner. Sporozoites of P. gallinaceum were collected from infected Aedes aegypti mosquitoes and used to immunize rabbits. The serums from these animals were collected, fractionated and labeled as previously described. The antiserums were highly specific for the erythrocytic stages of each parasite. The results indicate that the fluorescent antibody technic may be usefully employed in malariology and that different stages of the parasite have common antigens.