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.
Rotaviruses (RVs) are a leading cause of severe gastroenteritis in both animals and human infants worldwide. The first porcine rotavirus strain was isolated from neonatal pigs by Woode and Bridge in 1974 (Zhang et al., 2024), marking a pivotal advancement in understanding the etiology of swine diarrhea. Neonatal and suckling piglets exhibit high susceptibility to RV infection, with morbidity rates exceeding 90 % in commercial swine populations, resulting substantial economic losses for the global livestock industry (Midgley et al., 2012; Vlasova et al., 2017). Beyond its impact on animal health, RVs pose a grave public health challenge. Rotavirus infections are associated with over 200,000 fatalities annually among children under the age of five, predominantly in Southern Asia and nations within sub-Saharan Africa (Ghonaim et al., 2025). Porcine rotavirus infection manifests clinically as severe watery diarrhea, vomiting, anorexia, and dehydration in swine, particularly in neonatal piglets (Gao et al., 2023; Patelet al., 2013). Despite interspecies transmission barriers and host range restrictions, genomic reassortment events between human and animal rotavirus A strains (RVAs) have been documented, driving its genetic diversity (Akari et al., 2023). This evolutionary plasticity has profound implications for both medical and veterinary epidemiology, as emerging evidence suggests porcine RVA strains may serve as zoonotic reservoirs for human, canine, and other animal infections (Qiao et al., 2024). The potential for cross-species spillover highlights the need for integrated surveillance strategies to mitigate the global health burden of rotavirus disease, which remains a leading cause of pediatric gastroenteritis and livestock productivity losses worldwide.
Rotaviruses (RVs), members of the Sedoreoviridae family, possess an 11-segmented double-stranded RNA genome encoding six structural proteins (VP1-4, VP6-7) and six non-structural proteins (NSP1-6) (Crawford et al., 2017; Matthijnssens et al., 2022). Currently, ten distinct species of rotavirus are classified, designated from A to J (LeClair et al., 2023), with RVA being of greatest biomedical significance due to its broad host range encompassing humans, swine, and diverse mammalian species (Vlasova et al., 2017; Gomez-Rial et al., 2020). The standardized genotype nomenclature (Gx-P[x]-Ix-Rx-Cx-Mx-Ax-Nx-Tx-Ex-Hx) reflects the genetic diversity across all 11 genomic segments, each encoding a distinct viral protein (Chen et al., 2019). Notably, G9 has emerged as the predominant RVA genotype in southern China between 2021-2023, accounting for 56.55 % of sequenced samples, followed by G5, G3, and G4, as well as other genotypes (Zhang et al., 2024; Qiao et al., 2024). This regional prevalence pattern corroborates global observations identifying swine as key reservoirs for human G9 RVAs, with documented interspecies reassortment events between porcine and human strains (Wu et al., 2017; Miao et al., 2022). Despite its clinical significance across veterinary and public health sectors, the G9P[23] genotype remains underrepresented in swine population studies, particularly regarding its evolutionary origins, host adaptation mechanisms, and zoonotic transmission dynamics.
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