# Evolutionary characterization and pathogenicity of a porcine G9P[23] rotavirus with gene segments linked to canine and giant panda strains

## TL;DR

A new porcine rotavirus in China shows genetic links to dog and giant panda strains, causing severe illness in piglets and raising concerns about cross-species transmission.

## Contribution

First report of a porcine G9P[23] rotavirus with gene segments from canine and giant panda strains in mainland China.

## Key findings

- The ZJ03 strain causes severe diarrhea and intestinal damage in piglets within 48 hours.
- ZJ03 replicates efficiently in MA104 cells, reaching a peak titer of 10^9.25 TCID50/mL.
- The VP3 and NSP1 genes of ZJ03 show high homology to giant panda and dog rotavirus strains, suggesting cross-species transmission risks.

## Abstract

•First report of a porcine G9P[23] rotavirus with gene segments linked to canine and giant panda strains in mainland China.•The genome analysis of the ZJ03 strain reveals that the VP3 gene (which exhibits the highest homology to the VP3 genome segment of the giant panda) and the NSP1 gene (which exhibits the highest homology to the NSP1 genome segment of the dog) carry a risk of cross-species transmission.•Experimental infection induces severe diarrhea and intestinal damage in piglets within 48 h.•ZJ03 strain exhibits high replication efficiency (peak titer 10^9.25 TCID50/mL) in MA104 cells.•Highlights zoonotic risks and ecological implications for wildlife conservation, particularly giant pandas.

First report of a porcine G9P[23] rotavirus with gene segments linked to canine and giant panda strains in mainland China.

The genome analysis of the ZJ03 strain reveals that the VP3 gene (which exhibits the highest homology to the VP3 genome segment of the giant panda) and the NSP1 gene (which exhibits the highest homology to the NSP1 genome segment of the dog) carry a risk of cross-species transmission.

Experimental infection induces severe diarrhea and intestinal damage in piglets within 48 h.

ZJ03 strain exhibits high replication efficiency (peak titer 10^9.25 TCID50/mL) in MA104 cells.

Highlights zoonotic risks and ecological implications for wildlife conservation, particularly giant pandas.

Porcine rotavirus A (RVA) has emerged as an increasingly consequential zoonotic pathogen, causing severe intestinal disorders across diverse mammalian species, including humans. During of an outbreak that struck nursing piglets with diarrhea, a porcine G9P[23] rotavirus, named as RVA/Pig-wt/China/ZJ03/2022/G9P[23] (hereafter referred to as ZJ03), was identified. To further elucidate the evolutionary diversity of ZJ03, a comprehensive analysis of all genome segments was conducted. The genome constellation was identified as G9-P[23]-I5-R1-C1-M1-A8-N1-T1-E1-H1. Nucleotide sequence identity and phylogenetic analyses indicated that the VP3 and NSP1 genes of ZJ03 are most closely related to the corresponding genes of the giant panda strain and the dog strain, respectively, showing the highest homology at 95.73 % identity and 94.64 %. The remaining genes demonstrated the most intimate relationship with porcine strains. Their highest homology levels ranged from 95.98 % to 99.49 % similarity. Therefore, evidence suggests interspecies transmission and genetic reassortment events between porcine, canine, and giant panda rotavirus strains. To evaluate the pathogenicity of ZJ03 strain, we experimentally infected 3-day-old piglets oral inoculation with the PoRV ZJ03 strain at a dose of 2 × 10^5.5 TCID50/ml per piglet. The infection resulted in severe diarrhea in all piglets, which occurred at 48 h post-infection (hpi), accompanied by sustained viral shedding and characteristic small intestinal villous atrophy, indicating significant damage to the intestinal epithelium. In vitro, ZJ03 exhibited efficient replication kinetics in MA104 cells, reaching peak titers of 10^9.25 TCID50/mL at 36 h post-infection. This study reports the first documented case of a novel porcine G9P[23] rotavirus with gene segments linked to canine and giant panda strains in mainland China, characterized by high viral titer and virulence. The findings highlight the emergence of a previously unrecorded RVA strain with significant virological and ecological implications.