You can't control me, but you can control my actin...
The presence of actin in the nucleus has been known for a long time, and although it has been implicated in transcriptional regulation, chromatin remodeling, and structural support, little is known about what it is doing there.
Goley et al. describes that upon infection, baculovirus induces nuclear actin polymerization. After viral infection, cytoplasmic Arp2/3 complex is recruited into the nucleus where the presence of the viral capsid-associated protein, p78/83, activates Arp2/3 to induce nuclear actin polymerization. Surprisingly, the ability of p78/83 to activate Arp2/3 is required for viral replication.
Examination of conserved residues found in other Arp2/3 nucleators led the authors to make a DE384-5AA mutation of p78/83, which yields a reduced rate of Arp2/3 dependent actin nucleation in vitro. The same mutation shows aberrant viral morphology and decreased viral replication in vivo, due to the inability of p78/83 to activate the Arp2/3 complex.
All I can say is, this is the bee's knees.