Comparison of excretory/secretory and circulating antigens of Toxoplasma gondii by enzyme immunoassay and immunoblotting.

, , , , , and 1992. Comparison of excretory/secretory and circulating antigens of Toxoplasma gondii by enzyme immunoassay and immunoblotting. International Journal for Parasitology 22: 1083–1088. Toxoplasma gondii trophozoites (RH strain) were cultured in embryonic fibroblasts in order to study the kinetics of production of excretory/secretory antigens, and the results were compared to the production of circulating antigens in an in vivo mouse model. By capture-ELISA, excretory/secretory antigens were first detected on the fourth day of culture whereas circulating antigens were first detected 1 day after infection. Similar concentrations of antigens were detected in both models as evidenced by comparable absorbance values. By immunoblotting, the excretory/secretory antigens were also detected later compared to circulating antigens (day 4 vs day 1). Seven major polypeptides were detected in both antigen preparations, six of them having the same molecular mass (110, 75,48, 30, 24 and 22 kDa).