Component of the helicase/primase complex. Unwinds the DNA at the replication forks and generates single-stranded DNA for both leading and lagging strand synthesis. The primase synthesizes short RNA primers on the lagging strand that the polymerase elongates using dNTPs. Possesses helicase-like motifs and therefore may act as the helicase subunit of the complex. Associates with the primase and the primase-associated factor to form the helicase-primase complex. Belongs to the herpesviridae helicase family.