Diarrhea viruses in cattle are a serious threat to both livestock and human health, and the recent COVID-19 pandemic has highlighted the potential dangers of coronaviruses. In this study, we focused on three common diarrhea viruses in cattle: bovine coronavirus (BCoV), bovine norovirus (BNoV), and bovine rotavirus C (BRVC). Our research aimed to understand the prevalence and genetic characteristics of these viruses in cattle in Guangdong, China.
We collected 194 fresh fecal samples from adult cattle in Guangdong between September 2022 and January 2024. Through genetic analysis using various software tools, we identified 24 new enteric virus strains in cattle, including two BCoV strains (GD-GZ-01 and GD-GZ-02), one BNoV strain (BYN7), and 22 BRV strains (BRVB, BRVC, and BRVH).
The detection rates for BCoV, BNoV, and BRVC were 8.76%, 15.98%, and 5.67%, respectively. Phylogenetic and homology analyses revealed that the BCoV strains GD-GZ-01 and GD-GZ-02 were closely related to strains from Zhejiang and Xinjiang, China. The BNoV strain BYN7 contained new gene sequences and may have originated from a Sichuan yak strain. The 22 BRV strains formed distinct phylogenetic clusters, indicating novel genetic variants.
One of the most intriguing findings was the potential for zoonosis, as the BCoV strains showed a close genetic relationship with the human OC43 strain. Recombination analysis suggested that recombination events may have occurred between the bovine GD-GZ-01 and the human OC43 strain, raising concerns about the potential for cross-species transmission.
Our study also confirmed disparities in infection rates based on the type of sampling site. Slaughterhouses had the highest prevalence rates for all three viruses, suggesting that factors like herd density, equipment sharing, and movement of people and vehicles play a role in viral transmission.
The co-infection rate (with two or more viruses) was 6.19%, which is lower than previously reported rates in other regions of China. This could be due to differences in detection methods, sample size, sampling strategies, geographic variations, herd management practices, and animal density.
The complete genomes of the BCoV and BNoV strains were sequenced and submitted to the GenBank database. For BRVC, we sequenced the VP6 genome of the strains.
Molecular analysis indicated that the BCoV strains GD-GZ-01 and GD-GZ-02 likely originated from Zhejiang or Xinjiang provinces in China, highlighting the potential for cross-regional transmission. The BNoV strain BYN7 could be a new mutation from a Chinese Sichuan yak strain. Additionally, we identified 22 BRV strains representing new mutants and forming distinct phylogenetic clusters.
In conclusion, our study revealed the relatively low prevalence of BCoV, BNoV, and BRVC in cattle fecal samples in Guangdong, China. We reported the first prevalence data for BRVC in cattle in China and provided insights into the potential risks of cross-regional transmission, zoonotic spillover, and the emergence of novel mutant strains. Further research is needed to fully understand the cross-species transmission potential of BNoV strains and the pathogenicity of novel bovine rotavirus variants. These findings are crucial for developing effective surveillance and control measures for bovine viral diseases.
