Carboxyterminal region of hybrid leukocyte interferons affects antiviral specificity

Four hybrid human leukocyte interferon (IFN-alpha) genes have been constructed and expressed in Escherichia coli using molecular cloning methods. Plasmids containing genes encoding human interferons, IFN-alpha A, IFN-alpha D, IFN-alpha I and several hybrids of the different IFN-alpha genes (formed by in vitro recombination at common restriction endonuclease sites located within the DNA sequence encoding mature polypeptides) joined identically to an E. coli trp promoter gave rise to bacterial-produced interferons with distinctly different antiviral activities. The expression plasmid which directs the synthesis of IFN-alpha I was constructed using a gene isolated from a human genomic library in a manner similar to the previous expression of IFN-alpha A and IFN-alpha D cDNA clones. The use of a cell-free transcription-translation system has allowed the calculation of the specific activities of IFN-alpha made from isolated DNA fragments containing these hybrid IFN-alpha genes. These bacterially-derived interferons vary considerably in their ability to inhibit vesicular stomatitis virus (VSV) in different mammalian cells. The results show that the cloned hybrid interferons have unique antiviral activities when compared with the parent interferons, and they demonstrate that more active IFN-alpha s can be made using recombinant DNA techniques.