Production and Evaluation of Recombinant Granule Antigen Protein GRA7 for Serodiagnosis of <i>Toxoplasma gondii</i> Infection in Cattle

Abstract

The precise detection of Toxoplasma gondii infection in cattle has important public health significance. In the present study, recombinant granule antigen protein GRA7 was evaluated as a potential diagnostic marker for T. gondii infection in cattle by an indirect enzyme-linked immunosorbent assay (ELISA) using the reference serum samples determined by immunofluorescence assay and Western blotting, showing that GRA7-ELISA has a sensitivity of 96.4%, and a specificity of 98.6%. The detection results by GRA7- and Toxoplasma lysate antigen-based ELISAs were compared, indicating that no significant difference (p>0.05) and perfect agreement (κ=0.74) was observed between the two tests. Receiver operating characteristic analysis showed a relative sensitivity and specificity of 100% and 97.3% at the cut-off value of 0.3 for GRA7-ELISA. These data demonstrate that GRA7 is a promising serodiagnostic marker for T. gondii infection in cattle.