IFN-alpha 4,Produced by macrophages, IFN-alpha have antiviral activities. Interferon stimulates the production of two enzymes: a protein kinase and an oligoadenylate synthetase.The interferons (IFN) are a family of cytokines with potent antiviral, antiproliferative and immunomodulatory properties, and are classified based on their binding specificity to cell surface receptors . The type I IFNs bind to the interferon alpha receptor (IFNAR), which consists of two subunits: IFNAR1 ( alpha -subunit) and IFNAR2 ( beta -subunit). This binding contributes to TNF-alpha induced signaling . Both the human and mouse genome code for more than a dozen closely related IFN-alpha subtypes and the various IFN-alphas share about 80% sequence homology among them . The mouse IFN-alpha 4 consists of 186 amino acids (aa) including a 24 aa signal peptide and a 162 aa IFN-alpha 4 mature domain. The mature mouse IFN-alpha 4 shares 58% and 76% sequence identity with mature human and rat IFN-alpha 4, respectively. The mouse IFN-alpha 4 reduces the local replication of murine cytomegalovirus in the tibia muscle. mIFN-A4 is a strong activator of Mx gene and was shown to be very effective in reducing splenomegaly .