Construction of expression system controlled by T7 promoter at different expression level in mammalian cells

The plasmid carrying the gene for T7 RNA polymerase and plasmid carrying neo~(r) gene were cotransfected into CHO cells. Slot-blot and Southern tests showed the T7 RNA polymerase gene was integrated into host chromosome and expressed in cells. Plasmid pT7CAT carrying report gene was transfected into CHO cells with and without T7 polymerase gene, respectively. The results demonstrated that CAT report genes were expressed in different level in host cells with and without integrated T7 polymerase gent.