ABSTRACT
Human papillomaviruses (HPVs) are small, epitheliotropic, doublestranded DNA viruses that consist of an 8 kilobase (kb) genome contained within an icosahedral capsid. Approximately 100 different genotypes have been identified to date, and these can bedivided into two groups according to the type of stratified epithelium infected-skin or mucosa (Table 1). A further classification parameter relates to the potential of the virus to induce malignant changes in the infected tissue, a particular, although not exclusive, property of the papillomaviruses that infect mucosal surfaces. Thus the group of ‘‘high-risk’’ viruses, which includesHPV16 andHPV18, is causally related to the induction of malignancies, especially of the uterine cervix [1-3], whereas members of the ‘‘low-risk’’ group, which includes HPV6 and HPV11, induce benign lesions, particularly in the anogenital mucosa. Benign hyperplasias of the skin, or warts, are very common, especially among children and young adolescents, and infection with viruses such asHPV1 andHPV2 can result in unsightly lesions on the
back of the hands (common warts) and painful lesions on the foot (deep plantar warts). Patients suffering from the rare genetic disease epidermodysplasia verruciformis develop extensive flat warts that can develop into squamous cell carcinomas, especially if infected with HPV types 5 or 8. Similar lesions are observed in renal transplant patients and, with the increase in numbers of immunosuppressed patients, infections with HPV are becoming a serious medical problem.
