Evaluation of a recombinant matrix antigen 1-based indirect enzyme-linked immunosorbent assay for serodiagnosis of Toxoplasma gondii infection in goats.

Toxoplasma gondii is an important zoonotic parasite affecting humans and livestock, and reliable serological tools are needed for disease surveillance in small ruminants. This study developed and evaluated a recombinant T. gondii matrix antigen 1 (TgMAG1) based indirect ELISA (iELISA) for detecting anti T. gondii antibodies in goat sera from northeastern Thailand. A truncated TgMAG1 fragment (amino acids 31-93) was selected to minimize cross-reactivity with Neospora caninum, expressed in Escherichia coli, and confirmed by SDS-PAGE, western blotting, and mass spectrometry. Overall, 213 goat sera were tested using latex agglutination test (LAT), indirect fluorescent antibody test (IFAT), and the TgMAG1-based iELISA. Seroprevalence was 34.7% by LAT and 38.5% by IFAT. Using LAT as the comparator, the iELISA showed 90.5% relative sensitivity (rSe; 95% CI: 81.7-95.3%), 85.6% relative specificity (rSp; 95% CI: 78.8-90.5%), and an area under the curve (AUC) of 0.91 (Cohen's kappa [κ] = 0.73); using IFAT, rSe was 92.7% (95% CI: 84.9-96.6%), rSp was 66.4% (95% CI: 58.0-73.9%), and the AUC was 0.85 (κ = 0.54). These findings suggest the TgMAG1-based iELISA offers high rSe for detecting T. gondii exposure in goats, though further validation with broader serum panels is warranted to confirm its rSp.