Kaposi's sarcoma-associated herpesvirus immediate early gene activity.

KSHV is the causative agent of three human proliferative disorders: Kaposi s sarcoma, primary effusion lymphoma, and multicentric Castleman's disease. Herpesvirus gene expression and viral replication is a complex, tightly regulated process involving latent, immediate early, early, and late viral gene transcription. The immediate early genes generally code for transcriptional activators and are critical for initiating viral transcription. KSHV encodes for approximately nine immediate early gene products, including ORF50, K8, K9, K3, K5, ORF57, ORF29b, ORF45, and K4.2. This review will address the activities of these proteins and what roles they play in virus replication, evasion of the host immune response, and viral pathogenesis.