Replicates the viral genomic DNA. This polymerase possesses two enzymatic activities: DNA synthesis (polymerase) and an exonucleolytic activity that degrades single-stranded DNA in the 3'-5' direction for proofreading purpose. The DNA synthesis very likely occurs by strand displacement. a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Single-chain monomer with multiple functions. Expressed in the early phase of the viral replicative cycle. The C-terminus seems to increase the affinity of the DNA for the polymerase active site, and thus increase processivity and decrease the accessibility of the DNA to the exonuclease active site. Belongs to the DNA polymerase type-A family.