Prevalence and genetic characterization of diarrhea viruses among cattle in Guangdong, China

Bovine coronavirus (BCoV), bovine norovirus (BNoV), and bovine rotavirus C (BRVC) are common diarrheal viruses in cattle and pose significant threats to herds and humans. In this study, we collected 194 fresh fecal samples from adult cattle between September 2022 and January 2024 in Guangdong Province, China. We presented the genetic characteristics of 24 newly identified enteric virus strains in cattle, including two bovine coronavirus (BCoV) strains (GD-GZ-01 and GD-GZ-02), one bovine norovirus (BNoV) strain (BYN7), and 22 bovine rotavirus (BRV) strains (BRVB, BRVC, and BRVH, representing groups B, C, and H, respectively). Genetic analysis was conducted via MEGA-X, MAFFT, RDP, SimPlot and Rstudio software. The reference strains' related genes were retrieved from GenBank for comparison and analysis via MegAlign and Snapgene.

The detection rates for BCoV, BNoV, and BRVC were 8.76% (17/194), 15.98% (31/194), and 5.67% (11/194), respectively. The phylogenetic and homology analyses showed that BCoV strains GD-GZ-01 and GD-GZ-02 were branched Chinese Zhejiang or Xinjiang strains from the Betacoronavirus group; BNoV strain BYN7 contains new gene sequences, the VP1 and VP2 genes, from the GIII.2 subgroup and may have originated from Chinese Sichuan yaks strain; The 22 BRV rotavirus strains (10 BRVB strains, 11 BRVC strains, and one BRVH strain) formed distinct phylogenetic clusters respectively. Additionally, BCoV strains have a close genetic relationship with the human OC43 strain. Furthermore, recombination analysis of the S genes showed that recombination events may have occurred between the bovine GD-GZ-01 and the human OC43 strain.

BCoV, BNoV, and BRVC exhibited relatively low prevalence levels in Guangdong, China. This is the first study to report the infection rate and genetic characterization of BRVC strains circulating in cattle in China. Our study confirmed that there were disparities in the infection rate regarding sampling site type. Genetic characterization suggested that the identified BCoV strains (GD-GZ-01 and GD-GZ-02) may have originated from Zhejiang or Xinjiang, BNoV (BYN7) could be a novel genetic variant from a Sichuan yak strain, and 22 BRV strains are novel genetic variants in new clusters. And, recombination events between the bovine GD-GZ-01 and the human OC43 strain suggested potential risks of zoonosis. It suggested potential risks of cross-regional and cross-species transmission of these viruses.