The role of HHV-8 in Kaposi's sarcoma

The epidemiology of Kaposi's sarcoma (KS) amongst North American and Northe rn European patients with AIDS suggests that an infectious agent other than HN is involved in its pathogenesis. Several lines of evidence indicate tha t human herpesvirus 8 (HHV-8), also termed Kaposi's sarcoma associated herp esvirus, is the sought after agent. DNA of HHV-8 is invariably found in all forms of KS where the virus is present in the RS spindle cell. In contrast , HHV-8 DNA is not regularly detected in most other malignancies. Antibodie s against HHV-8 are more frequently found in groups at risk Of KS, and HHV- 8 seroconversion precedes KS development. Several HHV-8 genes have been ide ntified that exhibit transforming potential in cell culture systems. In add ition, the virus encodes and induces several cytokines and angiogenic facto rs. This is of particular interest as models of KS pathogenesis developed b efore the discovery of HHV-8 emphasized the importance of inflammatory cyto kines. Although the expression pattern of viral genes in KS is not certain yet, it appears likely that the pathogenetic role of HHV-8 in KS may be rat her complex and differs from other virus-induced malignancies.