Molecular epidemiological investigation and genetic diversity of bovine enterovirus in China

Bovine enterovirus (BEV) is an important pathogen causing calf diarrhea and has been detected in the diarrheic calf feces, although its pathogenicity remains unclear. This study aims to investigate the epidemiological profile and genetic diversity of BEV. A total of 356 clinical samples were analyzed by RT-PCR, including feces and rectal swabs from diarrheic calves in 11 cities across four provinces of China during 2024, the results showed a BEV-positive rate of 5.9 % (21/356, CI: 3.89-8.85). The four-province survey revealed differential BEV prevalence, with the highest rate observed in Qinghai (14.29 %). Five subtypes (E2, F1, F2, F3, F8) were found to co-circulate, notably E2, F3 and F8 in Inner Mongolia. Genomic analyses indicated that purifying selection dominates BEV evolution. Following sequencing of ten P1 nucleotide fragments, sequence comparison and phylogenetic analysis were performed based on P1 and VP1. The results showed that the obtained sequences clustered within a branch containing BEV subtypes E2, F3, F2, F1, and F8, and were genetically more closely related to strains from Australia, Japan, and China. Additionally, through the comparison and analysis of the majority of amino acid residues entropy of VP1, VP2 and VP3, it was determined that the BEV VP1 protein showed a high level of genetic diversity. This study provides powerful insight for us to further understand the epidemic status and evolution of BEV in China.