The genetic diversity of bovine papillomaviruses (BPV) from different papillomatosis cases in dairy cows in Turkey.

Papillomaviruses (PVs) are epitheliotropic viruses that cause benign proliferative lesions in the skin (warts or papillomas) and mucous membranes of their natural hosts. In bovines specifically, 13 types of Bovine papillomaviruses (BPVs) are currently described in the literature, although the actual number may be greater than 20. BPV types are classified into four genera based on homology within the genomic regions of the L1 ORF, the most conserved sequence. This study conducted molecular typing of BPV in dairy cows with different papillomatosis cases and investigated the presence of co-infections across distinct BPV types in the same sample. After carrying out PCR using degenerate primers and type specific primers, 35 BPV suspected samples were detected as positive for BPV and these samples were used for typing using sequence analysis/PCR with type-specific primers. This analysis identified BPV-1, -2, -3, -4, -6, -7, -9 and -10, new putative types (BPV/BR/UEL6-like viruses) and the previously described putative type viruses (BAPV-6) in the 35 BPV-positive samples. In addition, co-infections across different BPV types were widely detected in the BPV-positive samples.  This study shows that PCR assays using degenerate primers to amplify partial fragments of the L1 gene followed by sequencing is useful for genotyping BPV. However, results need confirmation using type-specific primers in order to consider co-infections. In addition, this study identified a new putative type (in the same cluster as BPV/BR/UEL6-like viruses) and the previously described putative type viruses (BAPV-6) in teat papillomatosis of Turkish dairy cows. The study shows that it is essential to identify BPV types and their prevalence/distribution, and also to determine the clinical consequences of infection for the development of prophylactic and/or therapeutic procedures.