Original Article

Detection of bovine papillomavirus in an equine cell line as a contaminant

---

Abstract

Bovine papillomaviruses (BPV) are members of the family Papillomaviridae. Papillomaviruses are usually species-specific and epitheliotropic. Delta-BPVs are an exception to this rule in that they can also infect fibroblasts and non-bovid ungulates. Cell cultures are essential for performing in vitro studies, analysis of virus biology, vaccine production, tissue engineering and toxicity testing. In this context, cell line contamination constitutes a significant problem. In this study, various cell lines (n=27) were assessed for potential BPV contamination. To this aim, DNA was extracted from cell cultures and then screened for the presence of papillomavirus L1 capsid gene DNA using a consensus polymerase chain reaction (PCR) system. Immunofluorescence (IF) staining was used for viral protein detection. Intriguingly, one cell line derived from equine dermis tested positive by PCR and subsequent IF staining for L1. Amplicon sequencing followed by computed L1 DNA sequence alignment led to the identification of a new putative BPV type, revealing the highest identities with Delta-BPV types 1 (76%) and 2 (73%). To the authors’ knowledge, this is the first report on the presence of a putative BPV as a viral contaminant in cell cultures that possibly represents an unknown Delta-BPV.