Abstract
Toll-like receptors (TLRs) are known to be activated in Central Nervous System (CNS) viral infections and are recognized to be a critical component in innate immunity. Several reports state a role for particular TLRs in various CNS viral infections. However, excessive TLR activation was previously reported by us in correlation with a pathogenic, rather than a protective, outcome, in a model of SIV encephalitis. Here we aimed at understanding the impact of TLR-mediated pathways by evaluating the early course of pathogenesis in the total absence of TLR signaling during CNS viral infections. We utilized a mouse model of sublethal West Nile virus (WNV) infection. WNV is an emerging neurotropic flavivirus, and a significant global cause of viral encephalitis. The virus was peripherally injected into animals that simultaneously lacked two key adapter molecules of TLR signaling, MyD88 and TRIF. On day 2 pi (post infection), MyD88/Trif-/-mice showed an increased susceptibility to WNV infection, and revealed an impairment in innate immune cytokines, when compared to wild type mice (WT). By day 6 pi, there was an increase in viral burden and robust expression of inflammatory cytokines as well as higher cell infiltration into the CNS in MyD88/Trif-/-, when compared to infected WT. A drastic increase in microglia activation, astrogliosis, and inflammatory trafficking were also observed on day 6 pi in MyD88/Trif-/- Our observations show a protective role for TLR signaling pathways in preventing lethal encephalitis at early stages of WNV infection.
Original language | English (US) |
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Pages (from-to) | 84-95 |
Number of pages | 12 |
Journal | Brain Research |
Volume | 1574 |
DOIs | |
State | Published - 2014 |
Keywords
- MyD88
- Toll-like receptors (TLRs)
- Trif
- West Nile virus
ASJC Scopus subject areas
- General Neuroscience
- Molecular Biology
- Clinical Neurology
- Developmental Biology