Development and optimization of an ELISA method to detect Toxoplasma gondii oocyst infection in cats

Toxoplasmosis caused by Toxoplasma gondii (T. gondii) is a zoonotic disease with great medical and veterinary significance. Felines, the definitive hosts of T. gondii, play a crucial role in the transmission of toxoplasmosis. The booming pet industry has led to more cats and cat-owning families, increasing the risk of toxoplasmosis transmission from animals to humans. Monitoring feline T. gondii infection accurately is crucial for reducing transmission risks. However, existing diagnostic methods focus on detecting whether cats are infected with T. gondii but fail to trace whether feline toxoplasmosis infections originate from oocysts or cysts. In this study, we assessed four late-stage development abundant proteins that were highly expressed specifically in sporulated oocysts to evaluate their specificity in binding to cat anti-T. gondii-oocyst serum. The LEA880 protein can only specifically react with cat anti-T. gondii-oocyst positive serum, but not with cat anti-T. gondii-cyst positive serum or negative cat serum. The optimized indirect enzyme-linked immunosorbent assay (iELISA) method based on the LEA880 protein exhibits good specificity and sensitivity in detecting T. gondii oocyst infection in cats.