Genomic surveillance highlights key VP4/VP7 regions, dominant genotypes, and reassortment in bovine rotaviruses among diarrheic calves in China

1 A 21.46% detection rate of bovine RVs in diarrheic calves across 15 provinces in China during 2022-2023 shows clear seasonality and geographic patterns. 2 Key genomic regions in VP4/VP7 genes were identified for precise genotyping, and the genotypes of G6, G10, P[1], P[5], and P[11] are widely distributed in China. 3 A novel G10P[11] strain provides evidence of complex reassortment and ongoing evolution of bovine RVs. Bovine rotaviruses (RVs) have been confirmed as the important pathogen responsible for calf diarrhea, and in some instances posing a significant threat to public health. The genetic diversity of bovine RVs with at least thirteen P and fifteen G genotypes poses challenges to establish accurate detection methods and collect convincing clinical data, emphasizing the importance of understanding the epidemiological and genomic characteristics for combatting outbreaks. In the present study, the prevalence of bovine RVs in diarrheic calves across 15 provinces in China during 2022-2023 was monitored at a rate of 21.46%, and exhibits certain levels of seasonality and geographic specificity. By a comprehensive analysis based on 62 entire VP4 (determining P genotype) and 84 entire VP7 (determining G genotype) genes, two specific regions within the VP4 and VP7 genes, ranging from 310 to 595 bp and 260 to 631 bp, respectively, were identified as more accurate targets for assessing the evolutionary mechanisms of bovine RVs. Genotyping and phylogenetic analysis based on these genomic segments revealed the complexity of bovine RVs epidemics in China, with the dominant genotypes being G6 and P[1], and other genotypes such as G10, P[5], and P[11] being widely distributed. Further analysis in strain CHN/HLJ/N3/2023/G10P[11] provided evidence of multiple-genera reassortant and ongoing evolution of rotaviruses at the whole genome level. This comprehensive research brings valuable insights into the genetic patterns of bovine RVs, and such understanding is essential for addressing the challenges posed by the diverse genotypes of bovine RVs, which can significantly contribute to effective control measures against outbreaks in bovine populations.