A comprehensive multi-epitope recombinant protein strategy for accurate serological detection of Toxoplasma gondii infection.

Toxoplasma gondii is a globally prevalent zoonotic parasite responsible for toxoplasmosis. Accurate serological diagnosis remains challenging due to the lack of standardized, high-performance antigens. In this study, we designed a recombinant multi-epitope protein (ME-TG) by selecting B-cell epitopes from four immunodominant antigens: SAG1, GRA7, GRA4, and GRA14. The ME-TG construct was expressed in E. coli, purified, and evaluated using ELISA across 189 serum samples, including acute (n = 45), chronic (n = 38), healthy controls (n = 62), and individuals with other parasitic or bacterial infections (n = 42). The ME-TG-based ELISA demonstrated 98% sensitivity for both IgG and IgM detection, and 100% specificity, with no observed cross-reactivity. These findings highlight the diagnostic potential of ME-TG as a standardized serological marker for human toxoplasmosis. Further validation using larger, geographically diverse cohorts and additional T. gondii antigens is recommended to enhance clinical applicability.