Human herpesvirus 8 and the biology of Kaposi's sarcoma

Kaposi's sarcoma (KS) is the leading neoplasm of AIDS patients and also occurs at a lower frequency in HIV-negative hosts. Epidemiologic evidence suggests that a sexually transmitted agent or cofactor other than HIV plays a key role in KS development. The DNA of a novel herpes-virus (termed human herpesvirus 8 (HHV8) or KS-associated herpesvirus (KSHV)) is regularly associated with both the AIDS-related and HIV-negative forms of the disease. Seroepidemiologic studies suggest that HHV8 is sexually transmitted and show that HHV8 infection is tightly linked to KS risk. Infection Precedes tumor development and targets the spindle (endothelial) cell component of the tumor, thought to be the dominant cell in KS pathogenesis. Most such cells are latently infected, but tumors also appear to harbor a small subpopulation of productively infected cells. Thus, mounting evidence supports the view that HHV8 is the sexually transmitted cofactor predicted by the epidemiology of KS. In addition, HHV8 also infects B lymphocytes and is associated with several uncommon lymphoproliferative syndromes in AIDS patients.