Overproduction of adenovirus DNA polymerase and preterminal protein in HeLa cells

Adenovirus (Ad) DNA polymerase (AdPol) and the preterminal protein (pTP) form a complex that is involved in the in vitro initiation of Ad DNA replication. Recombinant vaccinia viruses (vv) were constructed in which the genes encoding AdPol and pTP were cloned into a vaccinia/T7 hybrid expression-based vector downstream from the T7 promoter (pT7)/encephalomyocarditis virus (EMCV) 5'-untranslated region (UTR). HeLa cells infected with the recombinant vv-AdPol or vv-pTP or a mixture of both, together with the vv expressing T7 RNA polymerase produced significant levels of pTP and AdPol which were biologically active in the in vitro initiation of Ad DNA replication. These amounts of pTP and AdPol were only about two-fold less than the levels produced in insect cells infected with the recombinant baculovirus constructs expressing AdPol and pTP.