IFN-? is a type I interferon, which can be induced by virus-infected leukocytes. Members of the type I interferon family, which includes IFN-α, IFN-β, and IFN-?, signal through IFNAR-1/IFNAR-2 receptor complex, and exert antiviral and antiproliferative activities. IFN-? exhibits about 75% sequence homology with IFN-α, and contains two conserved disulfide bonds, which are necessary for full biological activity. Recombinant Human IFN-? is a 19.9 kDa protein consisting of 172 amino acid residues.