Plays a role in viral gene regulation and seems to be essential for KSHV reactivation. Disrupts host G1 cell cycle control thus allowing viral transcription and translation to proceed at the early stages of infection. Catalyzes its own SUMO modification as well as that of its interacting partners such as host TP53 AND RB1. Protein modification; protein sumoylation. Interacts with host HDAC1 and HDAC2, these interactions suppress HDAC activities. Interacts with protein ORF57. Interacts with protein vPK (PubMed:17108053). Sumoylated.