Characteristics of bovine enterovirus F in four provinces of China: isolation, pathogenicity and immunogenicity

Bovine enterovirus (BEV) is a contagious pathogen that can cause respiratory and gastrointestinal diseases in cattle, resulting in economic losses to the global livestock industry. However, there are currently no commercial vaccines available for BEV. In this study, BEV was detected in fecal samples from diarrheic cattle in China between 2023 and 2024, marking the first reported prevalence of BEV in diarrheic cattle from Sichuan province. Two strains, HN004-8 and HB002, were isolated in Madin-Darby bovine kidney (MDBK) cells and identified as BEV through reverse transcription-polymerase chain reaction (RT-PCR), transmission electron microscopy (TEM), indirect immunofluorescence assay (IFA), and viral growth kinetics analysis. The isolate HN004-8 exhibited pathogenicity in 7-day-old Institute of Cancer Research (ICR) suckling mice, causing diarrhea and significant growth retardation. The isolate displayed tissue tropism in mice, with viral loads detected in the kidneys, lungs and spleens at 7 days post-infection (dpi). Histopathological analysis revealed extensive tissue damage, including severe interstitial pneumonia, intestinal villus atrophy, and hepatic cytoplasmic lipid vacuolation. Preliminary immunogenicity evaluation of an inactivated HN004-8 emulsion agent showed the induction of BEV-specific IgG and neutralizing antibodies in mice. In summary, this study isolated two BEV strains and provided molecular characterization of BEV isolates in China, which may provide potential candidate strains for further vaccine development.