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Virus infection represents an intracellular invasion of host cells for the sole purpose of multiplication. Successful virus replication requires entry into tropic cells, usurping of the cellular machinery, and the production of progeny virions to initiate further rounds of infection. Establishment of the antiviral state in response to virus begins at the site of infection and requires the initiation of a preexisting signaling network designed to inhibit virus replication and aid in the establishment of this coordinated immune response. Integral components of this network include the IRF-3 and IRF-7 transcription factors that play essential roles in the cellular response to infection through virus induced phosphorylation by an unknown virus activated kinase. The objective of this research was to elucidate the viral antigen(s) required to induce the phosphorylation and subsequent activation of IRF-3 and IRF-7, to identify the molecular component(s) required in this activation process, and to decipher the mechanism(s) by which cellular recognition of virus infection initiates this antiviral response. We demonstrate that activation of this signaling network, following RNA virus infection, is dependent on viral entry, viral transcription, and viral translation and propose that the molecular requirements governing activation of IRF-3 and IRF-7 are the result of viral byproducts formed during the process of cytoplasmic RNA self replication; including both the formation of double stranded RNA and ribonucleoprotein complexes. Following cellular recognition of these motifs, signal transduction networks converge onto an IKK-related kinase structure composed of adaptor proteins bound to two kinase subunits, TBK-1 and IKKepsilon, which we propose to be essential components of the virus activated kinase. We demonstrate that TBK-1 or IKKepsilon activation results in the establishment of an antiviral state that renders cells non permissive to viral replic