Molecular characterization of bovine Deltapapillomavirus (BPV1, 2, and 13) DNA in equine sarcoids

Sarcoids are fibroblastic lesions, which are considered as the most common skin tumors of horses; spontaneous regression rarely occurs. The bovine papillomavirus (BPV) types 1 and 2 may be involved in the pathogenesis of sarcoids, and probably the recently described BPV type (BPV13) might be associated with the pathogenesis of this lesion. This study characterized the DNA of BPVs in sarcoids from 15 horses from Brazil by analyzing 20 cutaneous lesions (12 recently collected; 8 from formalin-fixed paraffin-embedded (FFPE) tissues). Histopathology confirmed the proliferative lesions as sarcoids. Three PCRs were performed to amplify papillomavirus (PV) DNA. For screening, the primers IFNR2/IDNT2 were used to amplify a fragment of the PV L1 ORF. The second primer set was complementary to a common sequence of the E5L2 genomic region of BPV1, 2, and 13. The third primer pair (FAP59/FAP64) targeted a fragment of the PVs L1 ORF. The screening and E5L2 PCRs yielded amplicons in all samples evaluated. The FAP amplicons identified BPV1, 2, and 13 only from fresh tissue samples. The phylogenetic analyses of E5L2 resulted in the identification of BPV1, 2, and 13 in 14 (70%), 2 (10%), and 4 (20%) sarcoids, respectively. Two horses demonstrated multiple lesions: the sarcoids of one of these contained only BPV1 DNA and those of the other contained three types of bovine Deltapapillomavirus (BPV1, 2, and 13). This study confirmed the presence of BPV1, 2, and 13 DNA in equine sarcoids. Moreover, these findings represent the first description of three types of BPV diagnosed in the same horse, as well as the first confirmation of BPV1 and 2 in horses from Brazil.