Evaluation of an indirect ELISA using recombinant granule antigen GRA1, GRA7 and soluble antigens for serodiagnosis of Toxoplasma gondii infection in chickens.

In the present study, recombinant granule antigen proteins GRA1, GRA7 and Toxoplasma soluble antigens (TSA) were evaluated as potential diagnostic markers for T. gondii infection in chickens by an indirect enzyme-linked immunosorbent assay (ELISA), showing a seroprevalence of 16.4% by GRA1-ELISA, and 15.5% by both GRA7- and TSA-ELISA in chickens. No significant difference was observed in the inconsistent results (P > 0.05), and a substantial agreement was found in the consistent results of the 3 tests (92.7-97.3%). Compared with the reference test Western blot, GRA7-ELISA showed the highest co-positivity and co-negativity rates. Receiver operating characteristic (ROC) analysis revealed a largest area under curve (AUC) of 0.99 (95% CI, 98-1.0), and a highest relative sensitivity (100%) and specificity (97.9%) for a cut-off value of 0.34 in GRA7-ELISA. These results of the present study showed that GRA7 is a potential diagnostic marker for the detection of T. gondii infection in chickens.