Bovine papillomaviruses

Bovine papillomaviruses have a major contribution to make in unravelling the mechanisms of oncogenesis by this group. Most papillomaviruses can exert their biologic effect only in vivo, but several of the bovine types transform fibroblasts in culture; the altered cells have measurable attributes such as anchorage independence, density inhibition, and tumorigenicity in nude mice. Another important feature is that subgenomic fractions of DNA can be transfected into cells and elicit transformation. It is, therefore, possible to undertake quantitative molecular biologic and genetic studies in a way which is impossible with most papillomaviruses. Large amounts of virus can be obtained from bovine tumors. The six currently characterized viruses have all been cloned by recombinant techniques, and are the subject of intensive comparative research in many laboratories.