A novel linear B-cell epitope on S2 protein of transmissible gastroenteritis virus identified using a monoclonal antibody.

BACKGROUND: Transmissible gastroenteritis virus (TGEV) is a devastating coronavirus that causes severe gastrointestinal symptoms and high mortality in piglets, resulting in substantial economic losses in the swine industry. The spike (S) protein, particularly its S2 subunit, plays a crucial role in virus-host membrane fusion and exhibits high conservation among TGEV strains. However, B-cell epitopes within the TGEV S2 protein remain largely uncharacterized. This study aimed to express and purify the TGEV S2 protein, generate monoclonal antibodies (mAbs) against it, and identify specific B-cell epitopes. RESULTS: We successfully expressed and purified the TGEV S2 protein using a prokaryotic expression system. Immunization of BALB/c mice with the purified S2 protein yielded mAb 12G8, characterized as an IgG2b isotype with a kappa light chain. The mAb 12G8 demonstrated specific reactivity against TGEV strains through multiple immunological assays. Epitope mapping identified (1109)QGQALS(1114) as the minimal B-cell specific epitope recognized by mAb 12G8, which exhibits high conservation across different TGEV strains. Three-dimensional structural modeling analysis localized this conserved epitope within the heptad repeat 1 domain of TGEV S2 protein. CONCLUSIONS: These findings advance the understanding of TGEV S2 protein antigenicity and provide valuable resources for developing improved diagnostic tools and therapeutic strategies against TGEV infection. The identification of a conserved B-cell epitope within the S2 protein establishes new avenues for targeted vaccine development and may contribute to more effective control measures against TGEV in the swine industry. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12917-025-04968-6.