TRANSCRIPTION MAPPING OF THE KAPOSIS SARCOMA-ASSOCIATED HERPESVIRUS (HUMAN-HERPESVIRUS-8) GENOME IN A BODY CAVITY-BASED LYMPHOMA CELL-LINE (BC-1)

Kaposi's sarcoma-associated herpesvirus (KSHV) gene transcription in t he BC-1 cell line (KSHV and Epstein-Barr virus coinfected) was examine d by using Northern analysis with DNA probes extending across the vira l genome except for a 3-kb unclonable rightmost region, Three broad cl asses of viral gene transcription have been identified. Class I genes, such as those encoding the v-cyclin, latency-associated nuclear antig en, and V-FLIP, are constitutively transcribed under standard growth c onditions, are unaffected by tetradecanoylphorbol acetate (TPA) induct ion, and presumably represent latent viral transcripts. Class II genes are primarily clustered in nonconserved regions of the genome and inc lude small polyadenylated RNAs (T0.7 and T1.1) as well as most of the virus-encoded cytokines and signal transduction genes. Class II genes are transcribed without TPA treatment but are induced to higher transc ription levels by TPA treatment, Class III genes are primarily structu ral and replication genes that are transcribed only following TPA trea tment and are presumably responsible for lytic virion production. Thes e results indicate that BC-1 cells have detectable transcription of a number of KSHV genes, particularly nonconserved genes involved in cell ular signal transduction and regulation, during noninduced (latent) vi rus culture.