Transient expression of murine interferon-alpha genes in mouse and monkey cells.

The coding regions of murine interferon-alpha (IFN-alpha) genes were combined with promoter and 3'-noncoding sequences from other eukaryotic genes. Transient expression of these fusion genes was achieved in monkey COS cells and in a mouse cell line (TOP cells) expressing polyoma virus (Py) large T antigen constitutively. The efficiency of the different expression plasmids was determined by measuring the amount of IFN secreted into the medium. Replacement of the 3'-noncoding region of an IFN-alpha gene by that of the rabbit beta-globin gene resulted in a fourfold higher IFN-alpha production. The SV40 early promoter and the Moloney murine leukemia virus (MoMLV) long terminal repeat (LTR) produced similar amounts of IFN-alpha in COS cells. However, a tandem combination of the SV40 enhancer/early promoter and the mouse metallothionein-I promoter appeared fivefold more active than the SV40 early promoter. In TOP cells the MoMLV LTR was found to be threefold more active than the Py early promoter.