[Studies on the circulating antigens in murine toxoplasmosis]

The appearance of circulating antigens in mice and rats infected with Toxoplasma gondii RH strain was observed by a counterimmunoelectrophoresis. The results were summarized as follows: In the group of mice intraperitoneally inoculated 10(6) tachyzoites, the circulating antigens appeared from 2 days after inoculations until die. Specific antibodies to this protozoa measured by a latex agglutination test were not detected. Since the circulating antigens were also detected in the groups of mice treated with cyclophosphamide or irradiation of X-ray before intraperitoneal inoculation of 10(6) tachyzoites, it was thought that the circulating antigens were derived from the active proliferation of protozoa, not from the destruction of protozoa by immune-lysis. In the group of mice subcutaneously inoculated 10(6) tachyzoites, the circulating antigens appeared from 5 days after inoculations until die. The specific antibodies also elevated at the same time. This result indicated that the substances of circulating antigens were different from the antigens coated on the particle for the latex agglutination test. Rats resisting to Toxoplasma gondii infections were intraperitoneally inoculated 5 X 10(7) tachyzoites. The circulating antigens did not appear in all rats, but the production of specific antibodies was observed. Sensitive methods such as a enzyme-linked immunosorbent assay and a radioimmunoassay for detection of the circulating antigens may be useful tools for diagnosis of acute toxoplasmosis.