Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 Production of type I interferons (IFNs) by mammalian cells serves as a first line of defense against invasion by viruses and some bacteria. The signaling events that trigger the transcription of type I IFNs involve the coordinate activation of several transcription factors, including interferon response factors (IRFs). Initiation of type I IFN transcription requires signal dependent phosphorylation. My seminar will focus on the signaling events in the host cell that are elicited by virus infection. In particular, I’ll discuss the role of two kinases, TBK1 and IKKε, in coordinating the host response to infection.