Expression of human β-interferon cDNA under the control of a thymidine kinase promoter from herpes simplex virus

The availability of an isolated interferon gene cDNA clone and biological assays for its expression, provide an opportunity to examine the functional role of sequences preceding the coding portion of the interferon gene. In the present study, we examined whether the human β-interferon (IFN-β) gene can be transcribed and induced efficiently after replacing the normal 5′ flanking sequences^1,2 with a defined promoter segment from another gene. For this purpose the coding portion of the IFN-β gene³ was inserted downstream from the promoter sequence and RNA start site of the thymidine kinase (TK) gene from herpes simplex virus type 1 (HSV-1; ref. 4). Expression of interferon activity under the control of the viral TK promoter in this chimaeric plasmid was demonstrated by microinjection into the nuclei of Xenopus oocytes^5,6 and by transfection into mouse cells⁷ followed by superinfection with herpes simplex virus.