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Three of four heifers housed together developed multiple cutaneous tumours in the linea alba and on the teats 3 months after the application of plastic muzzle plates with sharp tips to prevent mutual sucking and licking. Fibropapilloma with many koilocytes but few intranuclear inclusions was diagnosed histologically. The dermis showed neoplastic fibroblasts and a structureless intercellular matrix, and nonpurulent vasculitis was also recorded. Immunohistochemical examination with an antibody against L1 papillomavirus antigen demonstrated intranuclear positivity in single cells of the granular and cornified layers and in many mesenchymal cells in the fibrous parts of the tumours. CD3-positive lymphocytes were present in the wall of some blood vessels, and in the dermis and epidermis. Proliferating cell nuclear antigen was detected predominantly in the basal layer of the epidermis and in the superficial dermis. Electron microscopy revealed small intranuclear aggregates of virus particles in an epidermocyte, damage to desmosomes and disorganization of cytokeratin filaments in many epidermocytes. Aggregates of virus particles were revealed also in a fibroblast in the dermis. In blood capillaries of the corium, acute swelling, inflammation and necrosis of the endothelium were observed. By means of the polymerase chain reaction (PCR) and nucleotide DNA sequencing of the PCR product, the virus was identified as bovine papilloma virus type 1 (BPV 1). The presence of this virus in the tissue was further confirmed by in-situ hybridization with a BPV 1 probe.

Extensive papillomatosis was identified in a heifer born and raised in Scotland and a steer born and raised in England. In both cases, the papillomas extended from the mouth and tongue to the reticulum. Although cases of florid papillomatosis of the upper gastrointestinal tract occur relatively frequently in cattle grazing on bracken fern in the Scottish Highlands, no such cases have been reported previously in English cattle. Histopathological examination of the papillomas showed that the lesions were wholly epithelial, with acanthosis, hyperkeratosis and the pathognomonic koilocytes characteristic of papillomavirus infection. Bovine papillomavirus type 4 (BPV-4) was identified by molecular amplification and sequencing of the viral genome.

Oesophageal papillomas are known to occur in cattle infected with bovine papillomavirus type 4 (BPV-4), and BPV-4 papillomas may undergo malignant progression in cattle that feed on bracken fern. In the south of Italy, where bracken fern is common, examination of 1133 slaughterhouse cattle aged 4-12 years revealed oesophageal lesions (single or multiple peduncuolated proliferations, or mucosal thickening) in 147 (13%). These two types of lesion were consistent with exophytic and inverted papilloma, respectively. BPV-4 was detected by polymerase chain reaction (PCR) analysis in >60% of the samples in which oesophageal papilloma was diagnosed histopathologically. Nucleotide sequencing of the PCR amplicons confirmed the presence of BPV-4 in the papillomas. This is the first report of such infections in a European country other than Britain.

We have studied the papillomaviruses found in the hand warts of 60 butchers, most of them from 2 distant slaughterhouses. Warts differing in morphology and location were studied separately. The viruses were identified by molecular hybridization, restriction enzyme analysis and immunofluorescence. Four known human papillomaviruses (HPV-1, HPV-2, HPV-3, HPV-4) were detected and one hitherto unknown papillomavirus was identified in 9 butchers. The DNA of the latter virus did not anneal with any of the RNAs complementary to either HPV-1 to HPV-5 or bovine papillomavirus type 1 (BPV-1) DNAs, and showed a Hind II + III restriction enzyme cleavage pattern distinct from those of known HPVs and BPVs. This virus showed distinct antigenic properties, as shown by immunofluorescence, using HPV-1, -2, -3, -5, and BPV-1 antisera. It may represent a new type of human papillomavirus (HPV-7) or a yet unidentified animal papillomavirus. In addition, 6 butchers were found to be infected with a papillomavirus, distinct from the known skin HPVs and from BPV-1, which could not be characterized by restriction enzyme analysis. Eleven butchers were found to be infected by 2 viruses. A characteristic histological pattern was found to be associated with the different papillomaviruses.