Plays a role in the protection against apoptosis mediated by cytotoxic cells during the immune response to acute and persistent viral infection. Contributes therefore to latency establishment. Plays also a role in the inhibition of host starvation-induced autophagy which ultimately contributes to the viral chronic infection. Participates also in the viral genome replication within host nucleus (PubMed:28053098). Interacts with human NOP53; may sequester ORF16 in host nucleolus and reduce its antiapoptotic activity. Interacts with ORF55. Belongs to the Bcl-2 family.