title: An expression vector for high-level protein synthesis in Vero cells.
abstract: We have constructed two new multi-purpose cloning vectors, pNI1 and pNI2, that carry the Escherichia coli gene Ecogpt encoding the enzyme xanthine-guanine phosphoribosyl transferase as a dominant selective marker. The Ecogpt gene is under the control of either the long-terminal-repeat promoter of mouse mammary tumor virus, pNI1, or the simian virus 40 early promoter, pNI2. Another feature of the vectors is a polylinker preceded by the human metallothionein IIA promoter. We have used pNI2 for the synthesis of the hepatitis B surface antigen (HBsAg) at a high level in monkey Vero cells. We show that gene amplification and a concomitant stable increase of HBsAg synthesis can be achieved in these cells using modified selective medium containing hypoxanthine, aminopterin and thymidine, i.e., increasing the aminopterin and decreasing the hypoxanthine concentrations.
authors: Unité des Applications du Génie Génétique (G3), Institut Pasteur, France.
authors: N
authors: N
authors: Israel
authors: N
authors: N
authors: Chenciner
authors: C
authors: C
authors: Houlmann
authors: R E
authors: RE
authors: Streeck
mesh_terms: D000818:Animals; D005784:Gene Amplification; D005822:Genetic Vectors / Q000235:genetics*; D006514:Hepatitis B Surface Antigens / Q000096:biosynthesis; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis*; D014709:Vero Cells / Q000378:metabolism*
chemical_list: D006514:Hepatitis B Surface Antigens; D011994:Recombinant Proteins