Plays an essential role in the viral lytic DNA replication by acting as the polymerase accessory subunit. Stimulates the viral DNA polymerase activity and appears to function with it as a holoenzyme. Increases the processivity of the viral polymerase, probably by acting as a sliding clamp that prevents dissociation of the polymerase from the active template (By similarity). Homooligomerizes and adopts an oligomeric ring-shaped structure composed of 6 subunits. Forms a complex with the DNA-binding protein, the DNA polymerase subunit, and the alkaline exonuclease (By similarity). Belongs to the herpesviridae DNA polymerase accessory subunit family.