Isolation and characterization of a novel reassortant strain of Orthoreovirus mammalis from diarrheic pig.

Orthoreovirus mammalis (MRV) can infect a wide range of mammals, including humans and bats, and the cross-species transmission of the virus poses a potential threat to the health of humans and other animals. In this study, we identified a novel MRV strain from diarrheic pigs in Hunan Province, China. Genetic analysis revealed that the virus is a reassortant, containing segments derived from human, porcine, and mink MRVs. Designated as MRV3-HNU-XXS-2020, the strain clusters within Lineage IV of MRV3 and shows the highest nucleotide identity (98.79%) and amino acid identity (98.02%) to the MRV3 strain IND/MZ/3013789/reo derived from Indian pigs in 2017. The σ1 protein of the virus contains the amino acid residues linked to the sialic acid-binding site as well as neurotropism (198-204 NLAIRLP, 249I, 340D, 419E), suggesting a potential for broader mammalian infectivity. This study provides a basis for investigating the epidemiology, genetic evolution, and zoonotic spillover potential of MRV in mammals.