Prevalence and genetic characterization of bovine viral diarrhea virus in dairy cattle in northern China.

Background: Bovine viral diarrhea virus (BVDV) is one of the major viral pathogens responsible for respiratory disease complexes in cattle and other ruminants; it has spread worldwide and poses a significant threat to the cattle industry. To understand the prevalence and genetic diversity of BVDV in northern China, this study conducted an epidemiological survey of BVDV in dairy cows across 13 provinces in northern China from June 2022 to June 2024. A total of 2,199 nasal swab samples were analyzed by RT-PCR.

Results: The results revealed an overall positive rate of 6.05% for BVDV, with values of 6.47% from June 2022 to June 2023 and 5.59% from July 2023 to June 2024. Notably, the positive rate varied by region, with the highest prevalence in Shandong (9.62%) and the lowest in Hebei (1.61%). Phylogenetic analysis of 53 positive samples revealed that all belonged to BVDV-1, with the predominant sub-genotypes being 1a (47.17%), 1 m (28.30%), and 1c (9.43%). No BVDV-2 or BVDV-3 was detected, indicating that BVDV-1a is the most prevalent strain in northern China. This study also highlighted the genetic diversity of BVDV, with nucleotide homology among the sub-genotypes ranging from 70.2 to 92.1%.

Conclusions: An epidemiological survey of BVDV conducted in 13 provinces (regions) in northern China between 2022 and 2024 revealed a positive rate of 6.05%. The prevalent genotype identified was BVDV-1, with the predominant sub-genotypes being BVDV-1a, BVDV-1 m, and BVDV-1c. The findings of this study provide new evidence for the molecular epidemiology and genetic evolution of BVDV transmission in northern China, laying a foundational basis for the development of vaccination and control strategies against BVDV.