Scientists have found genetic similarities between a monkey herpesvirus and a human virus thought to be involved in Kaposi's sarcoma (KS), a cancer common in AIDS patients. Researchers hope the study of the monkey virus will lead to better understanding of the human virus and, perhaps, to new KS therapies.

KS is thought to be caused by human herpesvirus 8 (HHV-8), also known as KS-associated herpesvirus (KSHV). KS causes vascular tumors in tissues under the skin and in mucous membranes. Red or purple lesions develop on the skin and in the lungs, intestinal tract and lymph nodes. The virus most often causes cancer in people whose immune systems are weakened, such as AIDS patients and organ-transplant recipients.

Several years ago, researchers in New England isolated a herpesvirus from rhesus macaque monkeys that seemed very similar to human KSHV. Working with rhesus monkey rhadinovirus (RRV), Dr. Blossom Damania of the University of North Carolina-Chapel Hill and colleagues have identified three new genes that are very similar to genes in the human KS virus. The findings show that RRV is "an excellent model system" for studying KSHV, Damania said, noting that "these two viruses share so many similarities in the genes they contain and how they control the expression of those genes." By studying RRV, she said, scientists can better understand how KSHV is involved in the development of KS and blood cancer in humans.

The next step is to determine what roles the newly discovered genes play in the virus' life cycle, with the goal of preventing KSHV from causing malignancies in humans. Because RRV is much easier to grow in culture than large quantities of KSHV, RRV may serve as a proxy for studying the life cycle of KSHV.

The full report, "Kinetics of Expression of Rhesus Monkey Rhadinovirus (RRV) and Identification and Characterization of a Polycistronic Transcript Encoding the RRV Orf50/Rta, RRV R8, and R8.1 Genes," is published in the October issue of the Journal of Virology (2002;76:9819-9831).

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