Enhances viral DNA replication and virion release (PubMed:29437973). Plays a role in viral infectivity (PubMed:16731932). Induces apoptosis of primary erythroid progenitor cells (PubMed:19861680). Interacts with host GRB2; this interaction alters host cell environment by modulating host signaling pathways. Its expression is regulated by host RBM38, probably via RBM38-dependent splicing of the viral pre-mRNA.