Pathological investigation and molecular characterization of bovine papilloma virus-1 detected in cutaneous warts of cattle

The present investigation describes the genetic characterization of BPV-1 and its pathological features of cutaneous warts in cattle. A total of 7 clinical cases of cutaneous warts on various positions of cattle were studied at Mukteswar, Uttarakhand. The cases were confirmed by histopathology and molecular method. Grossly, dome shaped lesions were observed on nostril, around the eye, shoulder and neck region whereas single long cylindrical and dome shaped protruding growths were observed in teats. Histopathological study showed presence of hyperkeratinization, basket wave appearance, parakeratosis, koilocytosis, rete pegs formation in epidermal layer and fibroblast proliferation in dermal layer and pathologically diagnosed as fibropapilloma. In teat warts, the characteristic pathological lesions were hyperkeratinization, digit like proliferation, parakeratosis, keratohylinization with koilocytes which were diagnosed as papillomas. Two clinical cases of warts on teat revealed hyperplasia with mild cornification and thickening of epidermal layer. Immunohistochemistry, performed by using monoclonal mouse antibody against E2 protein of BPVs, revealed positive immunolabeling in the nucleus, cytoplasm and cytoplasmic membrane of basal, spinosum and granulosum layer. In PCR, 5 clinical samples were positive for BPV and based on sequence analysis it was identified as BPV-1. The phylogenetic analysis of the L1 gene placed the present BPV under a cluster of delta-papillomavirus. In conclusion, the confirmatory detection of BPV-1 in particular herd and its genetic characterization help in molecular epidemiology study and to set appropriate therapeutic and control measures.