Affiliation:
1. Departments of Medicine
2. Molecular Microbiology
3. Department of Immunology, University of Washington School of Medicine, Seattle, Washington 98195-7650
4. Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110
Abstract
ABSTRACT
Protection against West Nile virus (WNV) infection requires rapid viral sensing and the generation of an interferon (IFN) response. Mice lacking IFN regulatory factor 3 (IRF-3) show increased vulnerability to WNV infection with enhanced viral replication and blunted IFN-stimulated gene (ISG) responses. IRF-3 functions downstream of several viral sensors, including Toll-like receptor 3 (TLR3), RIG-I, and MDA5. Cell culture studies suggest that host recognizes WNV in part, through the cytoplasmic helicase RIG-I and to a lesser extent, MDA5, both of which activate ISG expression through IRF-3. However, the role of TLR3 in vivo in recognizing viral RNA and activating antiviral defense pathways has remained controversial. We show here that an absence of TLR3 enhances WNV mortality in mice and increases viral burden in the brain. Compared to congenic wild-type controls, TLR3
−/−
mice showed relatively modest changes in peripheral viral loads. Consistent with this, little difference in multistep viral growth kinetics or IFN-α/β induction was observed between wild-type and TLR3
−/−
fibroblasts, macrophages, and dendritic cells. In contrast, a deficiency of TLR3 was associated with enhanced viral replication in primary cortical neuron cultures and greater WNV infection in central nervous system neurons after intracranial inoculation. Taken together, our data suggest that TLR3 serves a protective role against WNV in part, by restricting replication in neurons.
Publisher
American Society for Microbiology
Subject
Virology,Insect Science,Immunology,Microbiology
Cited by
278 articles.
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