Use of recombinant antigens for detection of Toxoplasma gondii infection in swine.

Five recombinant Toxoplasma gondii antigens, designated B427, C51, C55, V22, and MBP30 were assessed for their potential use in an enzyme-linked immunoassay (EIA) for detection of T. gondii infection in swine. The antigens were evaluated with sera from young pigs that had been fed 1-10,000 T. gondii oocysts of the VEG or GT-1 strains. Results were compared with an EIA using a native T. gondii antigen extract. All 5 recombinant antigens, as well as native antigen, detected antibody responses as soon as 3 wk after infection in pigs inoculated with 1 or 10 oocysts of the VEG strain. This antibody response persisted, at varying levels, for 14 wk when the experiment was terminated. All antigens also detected antibody responses in pigs 4 wk after inoculation with 10,000 oocysts of the GT-1 strain. The antibody response recognized by native antigen remained high through 51 wk after inoculation. However, there was considerable animal-to-animal variation in responses to the individual recombinant antigens. Only antigens C51 and MBP30 consistently detected a positive antibody response over the entire 51-wk course of the experiment. These results suggest that these antigens might be useful for the serological detection of T. gondii infection in pigs.