79 - Human Papillomaviruses

Abstract

Human papillomavirus (HPV) infections of skin and mucosa are very common and in general cause benign papillomas or warts. More than 150 HPV types have been completely sequenced, and more types probably exist. Most infections are transient, subclinical, and cleared by a cellular immune response. Persistent infection with sexually transmitted high-risk mucosal types, mostly HPV-16 and -18, cause all cervical and most anal cancers, a subset of vaginal, vulvar, penile and oropharyngeal cancers, and rarely cancers of the digits. The three licensed subunit vaccines (bivalent, quadrivalent, and 9-valent) are comprised of empty virus-like particles (VLP); when administered prophylactically, they are highly efficacious in preventing type-specific persistent HPV infection and neoplasia. Epidermodysplasia verruciformis (EV) is a genetic disease that leads to an abnormal susceptibility to a large number of β HPV types. Patients with EV present with generalized cutaneous verrucae planae, pityriasis versicolor-like macules, and an early development of squamous cell cancer (SCC) in sun-exposed sites. In the general population, β HPV types are acquired early in life, and they have also been implicated in the initiation, but not maintenance, of SCC in immunocompromised patients.