Papillomaviruses are small tumor viruses with a genome of approximately 8000 base pairs. They are found in many different types and infect a wide range of animals (from birds to rabbits, dogs, sheep and cattle) and several primates including humans. So far, over 100 different types of human papillomavirus (HPV) have been identified, among which one-third infect epithelial cells in the genital t...