Cloning of full length cDNA, high-level expression and biological characterization of feline IL-12

A full length cDNA of feline interleukin(IL)-12 p35 and p40 subunits was cloned. By transferring the plasmids containing both the subunit genes to mammalian cells, we expressed biologically active feline IL-12. The expressed feline IL-12 has interferon-gamma-inducing activity against both human and feline peripheral blood mononuclear cells (PBMC) and stimulates cytotoxic T lymphocyte activity against herpes simplex virus-infected human PBMCs. There were two kinds of molecules (p75, p80) in the purified recombinant feline IL-12, and both molecules exhibited biological activity. The difference between p75 and p80 was the degree of the glycosylation of the p35 chain. Moreover, when we modified the cDNA of p35 by changing some codons and deleted the 5' and 3' non-coding regions, the expression level of IL-12 increased about 100 fold.