[Detection of circulating antigens of Toxoplasma gondii using immunoprecipitation reactions in murine toxoplasmosis].

Circulating antigens (AGC) of Toxoplasma gondii were detected by counter electro-immunodiffusion (CEID) from the fourth day, in mice OF1 infected with 1,000 and 5,000 Toxoplasma gondii RH strain trophozoites. The mean number of precipitant lines increased from 1.6 on the fourth day to 5.8 on the seventh day, after which no animals survived. With the "Prugniaud" cystogenic strain no AGC were detected in mice inoculated with 100 and 200 cysts. Other techniques used, such as double immunodiffusion and immunoelectrophoresis, were shown to be less sensitive than CEID, and of little use for the detection of AGC. These AGC present antigenic similarities with some cytoplasmic fractions, particularly the FC3 fraction, and some membranous fractions such as FM1, separated by Sephacryl S300 gel chromatography.