TANK is a negative regulator of Toll-like receptor signaling and is critical for the prevention of autoimmune nephritis

Interferon regulatory factors (IRF)-3 and IRF-7 are master transcriptional factors that regulate type I IFN gene (IFN-a/b)induction and innate immune defenses after virus infection. Prior studies in mice with single deletions of the IRF-3 or IRF-7genes showed increased vulnerability to West Nile virus (WNV) infection. Whereas mice and cells lacking IRF-7 showedreduced IFN-a levels after WNV infection, those lacking IRF-3 or IRF-7 had relatively normal IFN-b production. Here, wegeneratedIRF-36 IRF-7 double knockout (DKO) mice, analyzed WNV pathogenesis, IFN responses, and signaling ofinnate defenses. Compared to wild type mice, the DKO mice exhibited a blunted but not abrogated systemic IFN responseand sustained uncontrolled WNV replication leading to rapid mortality. Ex vivo analysis showed complete ablation of theIFN-a response in DKO fibroblasts, macrophages, dendritic cells, and cortical neurons and a substantial decrease of the IFN-bresponse in DKO fibroblasts and cortical neurons. In contrast, the IFN-b response was minimally diminished in DKOmacrophages and dendritic cells. However, pharmacological inhibition of NF-kB and ATF-2/c-Jun, the two other knowncomponents of the IFN-b enhanceosome, strongly reduced IFN-b gene transcription in the DKO dendritic cells. Finally, agenetic deficiency of IPS-1, an adaptor involved in RIG-Iand MDA5-mediated antiviral signaling, completely abolished theIFN-b response after WNV infection. Overall, our experiments suggest that, unlike fibroblasts and cortical neurons, IFN-bgene regulation after WNV infection in myeloid cells is IPS-1-dependent but does not require full occupancy of the IFN-benhanceosome by canonical constituent transcriptional factors. Citation: Daffis S, Suthar MS, Szretter KJ, Gale M, Jr., Diamond MS (2009) Induction of IFN-b and the Innate Antiviral Response in Myeloid Cells Occurs through anIPS-1-Dependent Signal That Does Not Require IRF-3 and IRF-7. PLoS Pathog 5(10): e1000607. doi:10.1371/journal.ppat.1000607 Editor: Ganes Sen, Cleveland Clinic, United States of America Received March 11, 2009; Accepted September 8, 2009; Published October 2, 2009 Copyright: ! 2009 Daffis et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permitsunrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This study was supported by NIH grants AI057568, U54 AI081680, U19 AI083019, and AI074973. The funders had no role in study design, data collectionand analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected]