Catalyzes DNA synthesis. Acquires processivity by associating with a heterodimeric processivity factor comprised of the viral A20 and D4 proteins, thereby forming the DNA polymerase holoenzyme. Displays 3'- to 5' exonuclease activity. Might participate in viral DNA recombination. Does not perform translesion synthesis across an abasic site. a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Interacts with A20. Component of the Uracil-DNA glycosylase(UDG)-A20-polymerase complex; A20 and UDG form a heterodimeric processivity factor that associates with E9 to form the processive polymerase holoenzyme. Ts42 is a temperature-sensitive mutant. PAArVg is a mutant resistant to the drug phosphonoacetic acid (PAA). NG26 is a double mutant with a temperature-sensitive lesion and a mutation rendering the virus resistant to PAA. Belongs to the DNA polymerase type-B family.