Serodiagnosis of ovine toxoplasmosis in Mongolia by an enzyme-linked immunosorbent assay with recombinant Toxoplasma gondii matrix antigen

Toxoplasma gondii matrix antigen 1 (TgMAG1), known as the 65-kDa protein, which is abundantly expressed in both bradyzoites and tachyzoites, was evaluated as a candidate for the development of a diagnostic reagent for ovine toxoplasmosis. The TgMAG1 gene was expressed in Escherichia coli as a fusion protein with glutathione S-transferase (GST), and the recombinant TgMAG1 (rTgMAG1) was tested in an enzyme-linked immunosorbent assay (ELISA). The ELISA with rTgMAG1 showed a highly specific reaction with sera from mice experimentally infected with T. gondii but not with the closely related Neospora caninum. The antibodies to TgMAG1 were detectable from the acute to the chronic infectious stages in a mouse model. A total of 175 serum samples collected from sheep in 7 provinces of Mongolia were examined for the serodiagnosis of T. gondii infection by the ELISA with rTgMAG1, and the results were compared with those from the commercialized latex agglutination test (LAT). Of 175 serum samples analyzed, 42 (24.00%) and 29 (16.57%) samples were positive by the ELISA and LAT, respectively. Of 29 LAT-positive samples, 27 (93.10%) were positive by the ELISA. These results suggest that rTgMAG1 could be used as a reliable antigen for the detection of T. gondii infection in sheep.