E1a-responsive mammalian host/vector system for the stable high-level expression of secreted proteins

We have demonstrated that the E1a protein(s) of adenovirus transactivated enhancer activity from the regulatory region of the P2 strain of BKV and from a poly GT element (GTe). By combining these elements, optimally spaced with the major late promoter (MLP) of adenovirus type 2 and synthetic leader sequence derived from the spliced version of the tripartite leader of adenovirus (TPL), we have generated a promoter unit on a HindIII cassette designated GBMT (GT, BKV-P2 enhancer, MLP, TPL). We have constructed GBMT-based vectors pGT-h, with the dominant marker conferring hygromycin B (Hyg) resistance, and plasmid pGT-d, with the murine dhfr cDNA conferring methotrexate (MTX) resistance.