Construction of expression plasmids producing high levels of human leukocyte-type interferon in Escherichia coli

An expression plasmid was constructed, consisting of the promoter/operator region of the tryptophan operon from Serratia marcescens and a synthetic ribosome-binding site ligated into pBR322. Leukocyte-type interferon gene fragments (IFN-alpha A and IFN-alpha C) isolated from a cDNA library from human lymphoblastoid (Namalwa) cells were inserted into the unique HindIII site of the expression plasmid, and the resulting recombinant plasmids directed the synthesis of up to 5 X 10(5) units of A-type preinterferon, 2 X 10(7) units of A-type mature interferon and 8 X 10(5) units of C-type mature interferon per liter culture.