Molecular Characterization of Equine-like G3P[8] Rotavirus Strains Detected in South Korean Children

The equine-like G3 rotavirus is a reassortant strain in which an animal-derived G3 genotype has recombined with a human-origin genetic backbone. Recently, this strain has spread across Asia and Europe. In this study, the VP7 and VP4 genes, along with the genomic backbone of 39 G3P[8] rotavirus strains detected in South Korean children with acute gastroenteritis between 2017 and May 2025, were analyzed. All strains harbored the equine-like G3 genotype for the VP7 gene, and segmental genotyping of VP7, VP4, and VP6 suggested that these strains possessed a DS-1-like genetic backbone (I2-R2-C2-M2-A2-N2-T2-E2-H2). All VP4 genes were confirmed as P[8]. Phylogenetic analysis revealed that these strains clustered with previously reported equine-like G3 strains from various regions, including East Asia. Although individual vaccination records were not available in the EnterNet surveillance data, the overall detection rate of rotavirus infection has declined following vaccine introduction. Nevertheless, equine-like G3P[8] strains have continued to appear sporadically in Korean children, underscoring the importance of ongoing genomic surveillance in the post-vaccine era. Overall, these findings indicate that equine-like G3P[8] strains with a DS-1-like backbone have been circulating for several years in the pediatric population in South Korea, offering important insights into vaccine effectiveness and the surveillance of reassortant rotaviruses.