HPV sketch of its lifestyle

Abstract

Human papillomaviruses (HPV) are small icosahedral DNA non-enveloped viruses, adapted to human beings from the very beginning, since the apparition of the first humanoids. They are part of the large papillomaviruses group, which co-evolved with the first reptile species, around 350 million years ago. These viruses persist for years and even decades together with their animal or human hosts, in epithelial cells and/or mucosae, being considered rather commensal or producing chronic unapparent “infections” in most cases. There are described more than 150 HPV species, included in Alpha, Beta, Gamma, and some in Miu and Niu genera. The mechanisms of co-evolution between the human host and HPV are complex and depend on the host immune tolerance (with unknown advantages from HPV, to be tolerated) and HPV replication, with the promotion of host epithelial cell persistence, which in the case of HPV species with ma­lig­nant risk could cause an “immortality” of the host-cell and consequently malignancy. The mucosal-associated HPV lesions, condyloma acuminatum and focal epithelial hy­per­plasia, are benign lesions caused by types of HPV with mucosal affinities. Other lesions are malignant, such as cervical or other anogenital cancers (of vulva, vagina, pe­nis and anus) and head and neck cancers. The HPV spe­cies associated with cancers are included mostly in Alpha HPV genus. Cutaneous associated HPV lesions – common warts, plantar warts, flat warts, filiform warts, pigmented warts, epidermoid cysts – are benign lesions associated with cutaneous HPV strains, but Bowen disease is a type of skin cancer associated with alpha HPV. There are also sug­ges­tions that some of non-melanoma skin cancers could be as­sociated with some beta HPVs. Curative measures in­clude to­pi­cal cytotoxic and antiviral agents, topical im­mu­no­mo­du­la­tory agents, intralesional immunotherapy, destructive me­thods and surgery. Vaccination is the only way to de­crease the incidence of HPV-induced cancers and should be in­di­ca­ted for both boys and girls before natural infection oc­curs.