Revealing novel and conservative T-cell epitopes with MHC B2 restriction on H9N2 Avian Influenza Virus (AIV)

B2 haplotype MHC has been extensively reported to confer resistance to various avian diseases. But its peptide-binding motif is unknown and the presenting peptide is rarely identified. Here, we identified the peptide-binding motif of B2 haplotype MHC Ⅰ molecules (X-A/V/I/L/P/S/G-X-X-X-X-X-X-V/I/L) in vitro using Random Peptide Library-based MHC-Ⅰ LC-MS/MS analysis. To further clarify the structure basis of the peptide binding motif, we determined the crystal structure of the BF2*02:01-PB2