BOVINE PAPILLOMAVIRUS AND CANCER

Bovine papillomavirus (BPV) induces papillomas of cutaneous or mucosal epithelia in cattle. The papillomas are benign tumours and generally regress, but occasionally persist and provide the focus for malignant transformation to squamous cell carcinoma, particularly in the presenc e of environmental cofactors. This has been experimentally demonstrate d for BPV-2 and cancer of the urinary bladder, and BPV-4 and cancer of the upper alimentary canal in cattle feeding on bracken fern. In this review, several aspects of the biology of the virus are described inc luding viral genome structure, regulation of transcription of the vira l oncogenes, function of the viral oncoproteins, cooperation between v irus and chemical cofactors in carcinogenesis, virus latency and proph ylactic and therapeutic vaccination programmes.