TANK-binding kinase-1 plays an important role during in vitro and in vivo type I IFN responses to dna virus infections

Abstract

TANK-binding kinase-1 (TBK1) and the inducible IκB kinase (IKK-i) have recently been shown to activate type I IFN responses elicited by intracellular detection of RNA or DNA from infecting viruses. Detection of viral RNA is mediated by retinoic acid inducible gene-I or melanoma differentiation-associated gene-5 pathways in which TBK1 and IKK-i have been demonstrated to play redundant roles in IFN activation. In this study, we have examined whether such redundancy occurs in the type I IFN response to DNA viral challenges by examining induction of IFNs and IFN-mediated signaling and gene programs in TBK1-/- macrophages. In contrast to the normal IFN responses in TBK1-/- macrophages infected with an RNA virus, IFN responses were severely abrogated during DNA virus infections in TBK1 -/- macrophages. Because both TBK1 and IKK-i are expressed in macrophages, our studies suggest that TBK1 and IKK-i differ functionally in DNA virus-mediated IFN responses; however, they are redundant in RNA virus-mediated IFN responses. Confirmatively, reconstitution of TBK1-/-IKK-i -/- fibroblasts revealed that TBK1 rescued IFN responses to transfected B-DNA to a much stronger degree than IKK-i. Finally, we demonstrate the requirement for the TBK1-IFN regulatory factor-3 pathway in host defense against a DNA virus infection in vivo. Copyright © 2009 by The American Association of Immunologists, Inc.