RING-finger E3 ubiquitin ligase that plays an important regulatory role during the initial stages of infection. Migrates to specific nuclear foci early in infection supposely to prepare the sites for viral replication by targeting and ubiquitinating host proteins. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Homooligomer. Auto-ubiquitinated. Belongs to the alphabaculovirus IE2 protein family.