Human papillomavirus (HPV) is a DNA virus from the papillomavirus family that is capable of infecting humans. Like all papillomaviruses, HPVs establish productive infections only in keratinocytes of the skin or mucous membranes. Most HPV infections are subclinical and will cause no physical symptoms; however, in some people subclinical infections will become clinical and may cause benign papillomas (such as warts [verrucae] or squamous cell papilloma), premalignant lesions that will drive to cancers of the cervix, vulva, vagina, penis, oropharynx and anus. In particular, HPV16 and HPV18 are known to cause around 70% of cervical cancer cases.