Human herpesvirus 8 (HHV8): I. Characteristics and epidemiology

HHV8 is a new herpesvirus recently identified in the Kaposi's sarcoma lesions, and initially named Kaposi's sarcoma-associated herpesvirus. It is a member of the gamma-2 herpesvirus family and it shows a number of homologies with the Epstein-Barr virus and the herpesvirus saimiri. HHV8 genome also codes for several proteins which are homologous to cellular proteins and could disturb the regulation mechanisms of cellular proliferation and apoptosis. This is the case for a viral IL6, an antiapoptotic factor homologous to Bc12, a viral cyclin, a member of the LRF family (interferon regulatory factors) and a G-protein-coupled receptor homologous to the IL8 receptor. Seroprevalence studies showed that HHV8 infection was not ubiquitous but rather limited to some geographic areas (Italy, Greece, Africa), and to some populations of homosexual and bisexual individuals with sexually transmitted diseases. To date, several lines of epidemiologic evidence suggest that this virus is sexually transmitted, although other routes of transmission cannot be excluded.