Schematic of HSV pol locus and conserved regions. Regions I through VII, similar among α-like DNA polymerases, are indicated as boxed areas with amino acid residue boundaries. Region VII purported to function in substrate recognition and binding is shown with the amino acid sequences from various DNA polymerases. The following polymerases are represented: HSV ; varicella-zoster virus (VZV) ; Epstein-Barr virus (EBV) ; Vaccinia ; Saccharomyces cerevisiae Pol δ (CDC2) ; human Pol α ; S. cerevisiae Pol α (Yeast Pol 1) ; T4 DNA polymerase (T4) . The changes identified in HSV-2 6757 DNA polymerase are indicated. The numbers adjacent to the various polymerase indicate the residue number for the beginning of shared exonuclease domain VII.