Detection of bovine herpesvirus 4 (BoHV-4) DNA in the cell fraction of milk of dairy cattle with history of BoHV-4 infection

We have demonstrated, by PCR and restriction enzyme analysis of the PCR pro duct, the presence of bovine herpesvirus 4 (BoHV-4) DNA in the cell fractio n of milk from dairy cattle with a history of BoHV-4 infection. We nest eva luated the infectious nature of BoHV-4 DNA in those cells. Cocultivation of a BoHV-4-sensitive cell line with BoHV-4 DNA-positive milk cell samples pr oduced cytopathic effects, The same result aas obtained from frozen and tha n ed milk tell fraction coming from the cell milk fraction PCR-positive cow s, ensuring that cells were killed and only infectious virus could be recov ered after cocultivation with sensitive cells. This report shows that infec tious BoHV-4 can be present in milk cells and that therefore nursing may be one of the transmission routes of BoHV-4.