Interactive mechanism between avian infectious bronchitis S1 protein T cell peptide and avian MHC I molecule

•To construct a 3D structure of the avian MHC–β2M complex.•Perform molecular docking of potential epitope peptide Sp6 from IBV S1 and the MHC–β2M complex.•Demonstrate the interactive mechanism between Sp6 and MHC. This study aims to construct a 3D structure of the avian major histocompatibility complex (MHC)–β2M complex through homology modelling technology, perform molecular docking of the predicted infectious bronchitis virus (IBV) S1 protein potential epitope peptide Sp6 (NQFYIKLT) and the avian MHC–β2M complex, and demonstrate the interactive mechanism between Sp6 and MHC using molecular dynamical simulations. The peptide Sp6 and the non-related peptide NP89–97 (PKKTGGPIY) were used to stimulate in vitro recombinant plasmid (pCAGGS-S1) avian splenic lymphocytes. Flow cytometric results show that CD8+ T lymphocytes reproduce stimulated by the Sp6 and the nonrelated peptide proliferate by 34.8% and 2.6%, respectively. Meanwhile, fluorescent quantitative PCR results show that the secretion of IFN-γ in avian splenic lymphocytes increases after Sp6 stimulation. These data suggest that Sp6 can induce the activated avian lymphocytes in vitro to produce CTL, which is the CTL epitope in IBV S1.