Isolation and partial 5'UTR-based molecular characterization of bovine enterovirus F from non-diarrheic cattle in...

Bovine enteroviruses (BEVs) are widely distributed among cattle worldwide and are commonly associated with subclinical infections, although their role in enteric, respiratory, and reproductive disorders remains incompletely understood. BEVs infect cattle as their natural host and are currently classified mainly within the species Enterovirus E and Enterovirus F. The advancement of virological research conducted as part of the elimination study may be affected by the concurrent circulation of enteric viruses, including BEV, in cattle populations. During a non-cytopathogenic BVDV elimination study, cytopathogenic agents unrelated to BVDV were incidentally detected and subjected to conventional virological and molecular identification.

For analysis, rectal and nasal swab samples were taken from 4 cattle showing mild respiratory symptoms on a farm, as well as blood samples from a total of 42 animals, including those that showed signs of contact. The cytopathogenic effect was detected in the Madin-Darby bovine kidney (MDBK) cell line by cultivation of fecal specimens. Two isolates were obtained and subjected to physicochemical characterization and determination of nucleic acid type. The fecal isolates were analyzed by RT-PCR using specific primers for possible key pathogens. The isolates showed resistance to chloroform and BrdU treatment, findings consistent with the characteristics of non-enveloped RNA viruses. Both isolates were positive in bovine enterovirus RT-PCR, and the molecular genetic analysis of the partial 5'UTR region of one of the isolates indicated that it belonged to the BEV-F clade. All 42 serum samples showed neutralizing activity at a dilution of ≥ 1:640 against the isolate used in the VNT.

This study, based on partial 5'UTR sequence analysis, provides preliminary molecular evidence of a bovine enterovirus associated with EV-F in Türkiye. Given the limited number of studies conducted in Türkiye, these findings could lead to more comprehensive molecular characterization and epidemiological investigations. Although BEVs are not routinely prioritized in diagnostic screening panels for cattle, the incidental detection of cytopathogenic BEV isolates, together with the high seropositivity rate observed among in-contact animals, suggests that BEVs should be considered in virological investigations.