The human papillomaviruses. An overview.

Papillomaviruses are small DNA viruses that are associated with proliferative squamous epithelial lesions in many higher vertebrates. In humans, over 50 distinct human papilloma viruses (HPVs) have now been recognized, and each is associated with a specific set of clinical lesions. Approximately 15 of these viruses have been associated with benign proliferative lesions of the genital tract, and a subset of these has been regularly associated with vulvar, penile, and cervical lesions that are generally regarded as precancerous. The regular presence of these same HPV DNAs in cancers of the cervix, penis, and vulva has supported the notion that these HPVs may have an etiologic role in these malignancies. The biology and natural history of HPV infections are poorly understood. In addition to the clinically apparent lesions induced, HPV-DNA can often persist latently in tissues that appear entirely normal. The cellular, hormonal, immune, and other physiologic factors involved in determining whether or not a HPV infection will be clinically manifest are not known. In general, there is a paucity of information concerning the host cellular and humoral immune responses to a HPV infection, though clinical observations indicate that such responses probably play a major role in the resolution of HPV-associated diseases.