UNIT 5.15 Gene Expression Using the Vaccinia Virus/ T7 RNA Polymerase Hybrid System

  1. Orna Elroy-Stein1,
  2. Bernard Moss2

Published Online: 1 MAY 2001

DOI: 10.1002/0471140864.ps0515s14

Current Protocols in Protein Science

Current Protocols in Protein Science

How to Cite

Elroy-Stein, O. and Moss, B. 2001. Gene Expression Using the Vaccinia Virus/ T7 RNA Polymerase Hybrid System. Current Protocols in Protein Science. 14:5.15:5.15.1–5.15.11.

Author Information

  1. 1

    Tel Aviv University, Tel Aviv, Israel

  2. 2

    National Institute of Allergy and Infectious Diseases, Bethesda, Maryland

Publication History

  1. Published Online: 1 MAY 2001
  2. Published Print: DEC 1998


This unit describes a transient cytoplasmic expression system that relies on the synthesis of the bacteriophage T7 RNA polymerase in the cytoplasm of mammalian cells. A gene of interest is inserted into a plasmid such that it comes under the control of the T7 RNA polymerase promoter (pT7). Using liposome-mediated transfection, this recombinant plasmid is introduced into the cytoplasm of cells infected with vTF7-3, a recombinant vaccinia virus encoding bacteriophage T7 RNA polymerase. During incubation, the gene of interest is transcribed with high efficiency by T7 RNA polymerase. For large-scale work, protocols are provided for insertion of the pT7-regulated gene into a second recombinant vaccinia virus by homologous recombination and subsequent coinfection with vTF7-3 into cells grown in suspension or for direct transfection into OST7-1 cells (a stable cell line that constitutively expresses the T7 RNA polymerase). Expressed protein is then analyzed by pulse-labeling and purified. One new development to this vaccinia virus/T7 RNA polymerase hybrid expression system described here is the VOTE inducible expression system, which eliminates the need to use two recombinant viruses or a special cell line.