The human papilloma virus is a naked DNA virus with a circular DNA structure that causes warts (strains 1, 2, 6, 11). The E6 gene product of the virus inhibits the p53 tumor suppressor gene, while the E7 gene product inhibits the retinoblastoma gene. Infection of the cervix (strains 16 and 18) or of the oropharynx (strain 16) commonly leads to squamous cell carcinoma. In HIV
patients, it can cause squamous cell carcinoma of the anus in men who have sex with men. Genital warts, or condylomata accuminata, are caused by strains 6 and 11. It is usually treated with some form of ablation if caught early since it only resides in the epithelium. There is a vaccine
available, made from a subunit of the virus particle. On biopsy and histology, dysplastic
squamous cells with "raisinoid" nuclei and hyperchromasia are seen.