Two viruses were isolated in 2017 from commercial pheasants with severe clinical signs and mortality in Shandong and Anhui provinces, China, respectively. We examined the pathogenic effects of the viruses in chicken embryos and the size and morphology of the virus particles, performed phylogenetic analysis based on the S1 gene and complete genomic sequences, and examined the antibody responses against infectious bronchitis virus (IBV). The results suggested that the viruses I0623/17 and I0710/17 were avian coronaviruses and were identified as pheasant coronaviruses (Ph. CoV), with greatest similarity to IBV. Further investigations of the antigenicity, complete genome organization, substitutions in multiple genes, and viral pathogenicity, replication, and shedding in chickens and pheasants showed obvious differences between Ph. CoV and IBV in terms of antigenicity, and viral pathogenicity, replication, and shedding in chickens and pheasants. The close genetic relationship, but obvious differences between Ph. CoVs and IBVs suggested the IBVs could be the ancestors of Ph. CoVs, and that Ph. CoVs isolated from different outbreaks may have evolved independently from IBVs circulating in the specific region by adaption in pheasants. This hypothesis was supported by analysis of the S1 gene fragments of the two Ph. CoVs isolated in the current study, as well as Ph. CoVs isolated in the UK and selected IBV strains. Such analyses indicated different evolution patterns and different tissue tropisms between Ph. CoVs isolated in different outbreaks. Further studies are needed to confirm this hypothesis by studying the complete genomic sequences of Ph. CoVs from different outbreaks and the pathogenicity of IBVs in pheasants to compare and clarify the relationships between Ph. CoVs and IBVs.
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