In vitro, can phosphorylate histone H1. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Expressed throughout the infection cycle beginning at 4 hours postinfection, first as a delayed-early gene and subsequently as a late gene. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.