REPLICATION-DEFICIENT VACCINIA VIRUS ENCODING BACTERIOPHAGE T7 RNA-POLYMERASE FOR TRANSIENT GENE-EXPRESSION IN MAMMALIAN-CELLS

The vaccinia virus/bacteriophage T7 hybrid transient expression system employs a recombinant vaccinia virus that encodes the T7 RNA polymera se gene, a plasmid vector with a gene of interest regulated by a T7 pr omoter, and any cell line suitable for infection and transfection. Alt hough high expression in a majority of cells is achieved, the severe c ytopathic effects of vaccinia virus and the safety precautions require d for use of infectious agents are undesirable features of the system. Here, we report the construction of a highly attenuated and avian hos t-restricted vaccinia virus recombinant that encodes the T7 RNA polyme rase gene (MVA/T7 pol) and demonstrate the use of the virus for transi ent expression in mammalian cells. MVA/T7 pol has reduced cytopathic e ffects compared to the previously used replication-competent vaccinia virus, while providing a high level of gene expression in multiple mam malian cell lines. (C) 1995 Academic Press, Inc.