Surveillance of porcine diarrhea-associated viruses in Anhui province, China (2022–2023) reveals rotavirus predominance and emergence of a highly pathogenic G9P[23] strain

Porcine rotavirus (PoRV) is widely prevalent in Chinese pig farms and causes substantial economic losses to the swine industry. Virus isolation remains technically challenging, and the pathogenicity of circulating strains in piglets is incompletely characterized. A total of 481 diarrhoeic samples were collected from Anhui province, China. PoRV was detected on 83.33% (15/18) of the farms, with a sample-level positivity rate of 28.48% (137/481). Phylogenetic analysis of the VP7 and VP4 genes identified G9 (50.00%) and P[23] (13.33%) as the predominant genotypes. A PoRV strain was successfully isolated and named RVA/Pig/China/GL/2022/G9P[23] (GL/2022), exhibiting a genomic constellation of G9–P[23]–I5–R1–C1–M1–A8–N1–T1–E1–H1. Comparative phylogenetic analyses revealed that GL/2022 shares high homology with both human and porcine RVA lineages, indicating possible interspecies reassortment. Importantly, this study represents the first systematic comparison of the evolutionary dynamics of GL/2022 with those of previously reported G9P[23] strains. Pathogenicity experiments demonstrated that GL/2022 induced severe enteric lesions and 50% mortality in neonatal piglets. These findings highlight PoRV's genetic complexity and zoonotic potential, providing critical insights for disease surveillance and vaccine development.