Representational difference analysis was used to isolate unique sequences present in more than 90 percent of Kaposi's sarcoma (KS) tissues obtained from patients with acquired immunodeficiency syndrome (AIDS). These sequences were not present in tissue DNA from non-AIDS patients, but were present in 15 percent of non-KS tissue DNA samples from AIDS patients. The sequences are homologous to, but distinct from, capsid and tegument protein genes of the Gammaherpesvirinae, herpesvirus saimiri and Epstein-Barr virus. These KS-associated herpesvirus-like (KSHV) sequences appear to define a new human herpesvirus.

The recently discovered KSHV DNA sequences occur in an unusual subgroup of AIDS-related B-cell lymphomas, but not in any other lymphoid neoplasm studied thus far. Our finding strongly suggests that a novel herpesvirus has a pathogenic role in AIDS-related body-cavity-based lymphomas.

Kaposi’s sarcoma (KS) is the most common cancer in HIV-infected untreated individuals. Kaposi’s sarcoma-associated herpesvirus (KSHV; also known as human herpesvirus 8 (HHV8)) is the infectious cause of this neoplasm. In this Review we describe the epidemiology of KS and KSHV, and the insights into the remarkable mechanisms through which KSHV can induce KS that have been gained in the past 16 years. KSHV latent transcripts, such as latency-associated nuclear antigen (LANA), viral cyclin, viral FLIP and viral-encoded microRNAs, drive cell proliferation and prevent apoptosis, whereas KSHV lytic proteins, such as viral G protein-coupled receptor, K1 and virally encoded cytokines (viral interleukin-6 and viral chemokines) further contribute to the unique angioproliferative and inflammatory KS lesions through a mechanism called paracrine neoplasia.