Genetic diversity, reassortment, and recombination of mammalian orthoreoviruses from Japanese porcine fecal samples

Abstract

Mammalian orthoreovirus (MRV) is a non-enveloped double-stranded RNA virus with a broad host range. MRVs are prevalent worldwide and have been isolated from various hosts, including humans, dogs, cats, wild boars, sewage, and pigs, in Japan. However, Japanese porcine MRV has not been genetically characterized yet. While investigating porcine enteric viruses including MRV, five MRVs were isolated from the feces of Japanese pigs using the MA104 cell culture. Genetic analysis of the S1 gene revealed that the Japanese porcine MRV strain isolates could be classified as MRV-2 and MRV-3. Whole genome analysis showed that Japanese porcine MRVs exhibited genetic diversity, although they shared homology with porcine MRV sequences deposited in the DDBJ/EMBL/GenBank database. Several potential intra-genetic reassortment events among MRV strains from pigs, sewage, and humans have been detected in Japan, suggesting zoonotic transmission. Furthermore, homologous recombination events were identified in the M1 and S1 genes of Japanese porcine MRV. These findings imply that different strains of Japanese porcine MRVs share a porcine MRV genomic backbone and have evolved through intra-genetic reassortment and homologous recombination events.