Research Note: Genetic characterization and pathogenicity of an epidemic variant strain of avian reovirus

The past few years have witnessed a rapid increase in cases of viral arthritis caused by avian reovirus (ARV) in chicken farms in China, attributed to the emergence of variant strains that render traditional vaccines ineffective, leading to substantial economic losses. In this study, we successfully isolated a novel ARV strain, designated as 2023ARV-GS-SDAU1, from chickens in a broiler flock vaccinated with an ARV vaccine in Gansu province. We performed wholegenome sequencing and assessed its pathogenicity through 2 infection routes: oral administration and intraperitoneal injection. Our analysis revealed signifi- cant variations in the crA gene, associated with the inhibition of interferon secretion, compared to known ARV strains. The highest nucleotide identity observed was below 80%. Additionally, the crC gene exhibited notable variations compared to its homologous strains within the same group. Multiple alignment of the amino acid sequences classified the 2023ARV-GS-SDAU-1 strain under genotype I. Furthermore, our pathogenicity experiments indicated that the isolated strain exhibited more severe pathogenicity when administered via intraperitoneal injection in SPF chickens. In summary, our data suggest that the 2023ARV-GS-SDAU-1 strain represents a novel variant circulating in broiler flocks in China. These findings enrich currently available genetic information on ARV strains and provide a new complete genome sequence.