Cloning and expression of murine immune interferon cDNA.

The murine immune interferon (IFN-gamma) gene was cloned and expressed under control of the simian virus 40 early promoter in the monkey COS-1 cell line. A protein is secreted from these cells having the biological, antigenic, and biochemical characteristics of natural murine IFN-gamma. Cloned murine IFN-gamma cDNAs were obtained by using RNA from both mitogen-induced murine spleens and the transfected COS cells, and both code for identical proteins. The mature murine IFN-gamma encoded is 136 amino acids long, 10 amino acids shorter than human IFN-gamma. The nucleotide homology between the murine and human IFN-gamma genes is 60-65%, whereas the encoded proteins are only 40% homologous. Murine IFN-gamma cDNA was expressed in Escherichia coli under trp promoter control.