biostudies-literatureWu QSpecial Foundation for State Basic Research Program of ChinaNational Key Research and Development Program of China108391https://www.ebi.ac.uk/biostudies/studies/S-EPMC7117385biostudies-literatureUnknown236Vaccination plays a vital role in controlling diseases caused by chicken infectious bronchitis virus (IBV). The continuously variant antigenicity of IBV limits the application of current vaccine strategies and serological diagnostic systems. S2 protein is an invariant that harbors broad neutralizing epitopes. However, little is known about the key amino acids that contribute to the broad-spectrum S2 epitopes. In this study, we aimed to elucidate the specific amino acids contributing to S2 epitopes. Site mutagenesis and peptide-based enzyme-linked immunosorbent assays (ELISAs) showed that 16R in S2 protein was a key amino acid mediating the antigenicity of S2 protein. S2-derived peptides with 16R, but not those with 16 K, could react with sera against different types of IBVs. Notably, a comVeterinary microbiologyPeptides with 16R in S2 protein showed broad reactions with sera against different types of infectious bronchitis viruses.PMC71173852013FY113300-42016YFD0500800Qin AShao HWu QLin ZQian KYe JfalsePeptides with 16R in S2 protein showed broad reactions with sera against different types of infectious bronchitis viruses.Vaccination plays a vital role in controlling diseases caused by chicken infectious bronchitis virus (IBV). The continuously variant antigenicity of IBV limits the application of current vaccine strategies and serological diagnostic systems. S2 protein is an invariant that harbors broad neutralizing epitopes. However, little is known about the key amino acids that contribute to the broad-spectrum S2 epitopes. In this study, we aimed to elucidate the specific amino acids contributing to S2 epitopes. Site mutagenesis and peptide-based enzyme-linked immunosorbent assays (ELISAs) showed that 16R in S2 protein was a key amino acid mediating the antigenicity of S2 protein. S2-derived peptides with 16R, but not those with 16 K, could react with sera against different types of IBVs. Notably, a com2019-01-01T00:00:00Z2019 Sep2025-04-04T22:45:25.725Z2020-05-22T15:35:05ZS-EPMC71173853150072810.1016/j.vetmic.2019.108391