Immunological analyses of antigens associated with experimental toxoplasmosis.

By immunoelectrophoresis of periotoneal exudates and toxoplasma cell antigens from mice and hamsters infected with Toxoplasma gondii, using their corresponding rabbit antisera absorbed with serum of uninfected animals, eleven precipitating antigens were distinguished and named No. 1--11 in order of increasing electrophoretic mobility. Monospecific rabbit antisera against two of these antigens (antigen No. 1 and 11) were prepared by immunization with antigen purified by zone electrophoresis, and were used for immunochemical analyses: the component with higher mobility on immunoelectrophoresis, antigen No. 11, was detectable only in association with toxoplasma infection of mice, hamsters, rats and guinea pigs. Antigen No. 11 was also detectable as a single major antigen in the medium of cultures of L cells infected with T. gondii, RH strain. In contrast, antigen No. 1 was detectable in uninfected mice in peritoneal exudates, and homogenates of thymus, liver and spleen, but not of brain or lymphocytes. In the latex agglutination test (LAT) for toxoplasmosis, anti-No. 1 serum gave a positive reaction, but anti-No. 11 gave a negative one. In 31 anti-toxoplasmosis sera examined, there was no correlation between the number of precipitating antibodies detectable by immunoelectrophoresis and the LAT titer.