First Isolation, Genomic Characterization and Experimental Infection of Bovine Coronavirus from Sheep

Bovine coronavirus (BCoV) is an important pathogen of cattle and has also been detected in several non-bovine ruminants. Although BCoV infection has been reported in sheep, virus isolation and genomic characterization from this host have not been described. In this study, two BCoV isolates were successfully recovered from fecal samples of sheep during an outbreak involving enteric and respiratory signs in Qinghai Province, China. Nearly complete genomes of the two isolates were obtained and were 100% identical to each other across the complete coding regions. Comparative genomic analysis showed that the complete coding regions of the sheep-derived isolates shared 100% nucleotide identity with a previously reported yak-derived BCoV strain, Yak/SWUN/NF2/2022 (OR603986). Phylogenetic analyses based on complete coding regions, S gene, and HE gene sequences showed that the sheep-derived isolates clustered with yak-derived BCoV strains previously identified in Qinghai Province, suggesting that closely related BCoV lineages may circulate among different ruminant hosts in the Qinghai-Tibet Plateau. Experimental infection provided evidence that the representative sheep-derived isolate was capable of establishing infection in sheep, as evidenced by viral RNA detection, seroconversion, and virus re-isolation from lung tissue. To our knowledge, this study represents the first successful isolation and genomic characterization of BCoV from sheep and provides new insights into the host range, genetic diversity, and potential distribution of closely related BCoV lineages among high-altitude ruminants.