Human Oncogenic Viruses: Old Facts and New Hypotheses

Resumo

Numerous studies on the nature of neoplastic growth have demonstrated that oncogenic viruses may be one of the factors causing cancer. According to various estimates, 10–20% of all human cancers are caused by viruses. For example, the Epstein–Barr virus (EBV), hepatitis B and C viruses, human papillomavirus (HPV), human T-lymphotropic virus type 1 (HTLV-1), human herpesvirus type 8 (HHV-8), and Merkel cell polyomavirus were implicated in initiating tumors. At the same time, the long period between viral infection and the manifestation of cancer significantly complicates the search for a causal relationship between the presence of a virus in the human organism and the malignant transformation. For this reason, the role of certain viruses in the initiation of neoplastic processes in humans remains an unresolved issue.