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'- to 5'-direction for proofreading purpose. a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Part of the replicase complex that includes the DNA polymerase, the polymerase clamp, the clamp loader complex, the single-stranded DNA binding protein, and the primase/helicase. Interacts with the polymerase clamp; this interaction constitutes the polymerase holoenzyme. The N-terminus contains the 3'-5' exonuclease activity. The C-terminus contains the polymerase activity and is involved in binding to the polymerase clamp protein. A beta hairpin structure is necessary for the proofreading function of the polymerase. Belongs to the DNA polymerase type-B family.