Diseases caused by human papillomaviruses (HPV).

Human papillomaviruses (HPV) are non-enveloped tumor viruses with a double stranded DNA approximately 8 kilobases in length. The viral genome is enclosed by a spherical capsid with icosahedral symmetry and a diameter of about 55 nm. More than 100 HPV types have been identified. They infect the squamous epithelia of skin and mucosa and usually cause benign papillomas or warts. Persistent infection with high-risk oncogenic HPV causes all cervical cancers, most anal cancers, and a subset of vulvar, vaginal, penile and oropharyngeal cancers. In recent years cutaneous beta-HPV types have been associated with the pathogenesis of non-melanoma skin cancers. Two prophylactic HPV vaccines based on virus-like particles (VLP) are licensed. These are up to 100% effective in preventing HPV 16 and HPV 18 infections and associated genital lesions in women, who have not been previously infected with these types. One vaccine also prevents genital warts caused by HPV 6 and HPV 11.