Isolation of New Transmissible Herpesvirus Suggests Additional Therapeutic Approaches for KS

A study demonstrating the existence of a new transmissible herpesvirusmay lead to additional therapeutic approaches for Kaposi's sarcoma(KS), a cancer that remains one of the major AIDS-associated malignancies.The study findings were reported at The American Society of Hematology's37th Annual Meeting in Seattle.

Kaposi's sarcoma can be fatal, and is characterized by the growthof lesions on the skin, in the gastrointestinal tract, or in thelungs, brains, or other organs. The cause of KS remains unclear,although present evidence suggests the involvement of a sexuallytransmitted agent.

The study, conducted by researchers at Cornell University MedicalCollege, isolated a fragment of herpes viral DNA (KSHV-DNA) fromAIDS-associated KS lesions and from AIDS-related body cavity-basedlymphomas. This DNA fragment also was found in non-AIDS relatedKS, further reinforcing the idea of an association between thenew herpesvirus and the pathology of KS.

When a tumor cell line that carries KSHV-DNA was utilized to isolateviral particles produced by these cells, it was noted that theKSHV-DNA was contained inside the viral particles since it wasprotected from the action of a DNA-degrading enzyme. The viruscontained in the isolate was infectious and could transmit theKSHV-DNA to human B-lymphyocytes.

This infection was blocked by foscarnet (Foscavir), an inhibitorof viral DNA replication that is currently approved by the FDAfor the treatment of cytomegalovirus retinitis, an opportunisticviral infection. Further studies may establish the potential offoscarnet as a treatment for KS.