Reactivation of Kaposi's sarcoma-associated herpesvirus infection from latency by expression of the ORF 50 transactivator, a homolog of the EBV R protein

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV), or human herpesvirus 8 , is a lymphotropic virus strongly linked to several AIDS-related neoplasms . The primary reservoir of infection consists of latently infected B lympho cytes and possibly other mononuclear cells. Viral reactivation from latency and spread from this lymphoid reservoir is presumably required for develop ment of nonlymphoid tumors like KS. Here we show that deregulated expressio n of a single viral gene, ORF 50, which encodes a transactivator able to se lectively upregulate delayed-early viral genes, suffices to disrupt latency and induce the lyric gene cascade in latently infected B cells. The identi fication of this gene opens the way to studies of the physiologic mechanism s controlling reactvation of KSHV from latency. (C) 1998 Academic Press.