PRIMARY CHARACTERIZATION OF A HERPESVIRUS AGENT ASSOCIATED WITH KAPOSIS-SARCOMA

Detection of novel DNA sequences in Kaposi's sarcoma (KS) and AIDS-rel ated body cavity-based, non-Hodgkin's lymphomas suggests that these ne oplasms are caused by a previously unidentified human herpesvirus, We have characterized this agent using a continuously infected B-lymphocy te cell line derived from an AIDS-related lymphoma and a genomic libra ry made from a KS lesion, In this cell line, the agent has a large epi somal genome with an electrophoretic mobility similar to that of 270-k b linear DNA markers during clamped homogeneous electric field gel ele ctrophoresis. A 20.7-kb region of the genome has been completely seque nced, and within this region, 17 partial and complete open reading fra mes are present; all except one have sequence and positional homology to known gammaherpesvirus genes, including the major capsid protein an d thymidine kinase genes, Phylogenetic analyses using both single gene s and combined gene sets demonstrated that the agent is a gamma-2 herp esvirus (genus Rhadinovirus) and is the first member of this genus kno wn to infect humans. Evidence for transient viral transmission from in fected to uninfected cells is presented? but replication-competent vir ions have not been identified in infected cell lines, Sera from patien ts with KS have specific antibodies directed against antigens of infec ted cell lines, and these antibodies are generally absent in sera from patients with AIDS without KS, These studies define the agent as a ne w human herpesvirus provisionally assigned the descriptive name KS-ass ociated herpesvirus; its formal designation is likely to be human herp esvirus 8.