This renewal application is focused on understand the molecular mechanisms of hepatic innate immunity that controls the outcome of hepatitis C virus (HCV) infection. We have shown that retinoic acid inducible gene-I (RIG-I) initiates the hepatic innate immune response upon recognition and binding of the pathogen associated molecular pattern (PAMP) consisting of 5'triphosphate with poly-uridine (poly-U/UC) within the HCV RNA. During acute infection this recognition of transmission/founder (T/F) viral genome by RIG-I results in its modification and activation to bind the MAVS adaptor protein on mitochondria-associated membranes (MAM) and signal hepatic innate immune defenses that restrict infection. Our preliminary studies now reveal that T/F genomes from patients exhibit remarkable variation within their poly-U/UC motif, and that this variation imparts differential recognition and binding by RIG-I that allows escape from non-self recognition. Moreover, we have found that signaling by RIG-I is dependent on formation of a RIG-I translocon protein complex to facilitates RIG-I cytosol-to-membrane translocation for MAVS interaction and signaling. Our studies now reveal that these activities are governed by the reversible acteylation of RIG-I, and that this process is likely controlled through the HDAC6 protein as a RIG-I cofactor of innate immunity. We show that HCV evades hepatic innate immunity via MAM targeting by the NS3/4A viral protease to cleave MAVS and disrupt RIG-I signaling, thereby facilitating chronic infection, and this action is dependent on stable NS3/4A-MAVS interaction on the MAM. Ablation of this interaction restores innate immunity to prevent acute to chronic HCV transition. We hypothesize that regulation of the RIG-I pathway and hepatic innate immunity are major determinants controlling the acute to chronic transition of HCV infection. We will therefore conduct studies to: 1) Define the features of RIG-I and the HCV poly-U/UC motif that confer PAMP binding and innate immune signaling activation, and determine how PAMP variation among T/F genomes influences acute innate immune induction by HCV;2) Determine the role of reversible acetylation in RIG-I translocon assembly and function;3. Identify the cognate/reciprocal motifs of NS3/4A and MAVS that mediate interaction and control of the RIG-I pathway.

Public Health Relevance

Liver disease from microbial infection is a major public health concern. Hepatitis C virus (HCV) infects the liver to cause liver disease, liver cancer, and death. Our studies will define the virus and host components that control HCV infection outcome and liver disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
High Priority, Short Term Project Award (R56)
Project #
2R56AI060389-12
Application #
8904856
Study Section
Hepatobiliary Pathophysiology Study Section (HBPP)
Program Officer
Koshy, Rajen
Project Start
2003-09-30
Project End
2015-07-31
Budget Start
2014-08-15
Budget End
2015-07-31
Support Year
12
Fiscal Year
2014
Total Cost
$493,950
Indirect Cost
$189,715
Name
University of Washington
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
605799469
City
Seattle
State
WA
Country
United States
Zip Code
98195
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Hong, MeeAe; Schwerk, Johannes; Lim, Chrissie et al. (2016) Interferon lambda 4 expression is suppressed by the host during viral infection. J Exp Med 213:2539-2552
Altfeld, Marcus; Gale Jr, Michael (2015) Innate immunity against HIV-1 infection. Nat Immunol 16:554-62
Kell, Alison M; Gale Jr, Michael (2015) RIG-I in RNA virus recognition. Virology 479-480:110-21
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Horner, Stacy M; Gale Jr, Michael (2013) Regulation of hepatic innate immunity by hepatitis C virus. Nat Med 19:879-88
Negash, Amina A; Ramos, Hilario J; Crochet, Nanette et al. (2013) IL-1β production through the NLRP3 inflammasome by hepatic macrophages links hepatitis C virus infection with liver inflammation and disease. PLoS Pathog 9:e1003330
Ireton, Reneé C; Gale Jr, Michael (2013) Systems biology analyses to define host responses to HCV infection and therapy. Curr Top Microbiol Immunol 363:143-67
Lau, Daryl T-Y; Negash, Amina; Chen, Jie et al. (2013) Innate immune tolerance and the role of kupffer cells in differential responses to interferon therapy among patients with HCV genotype 1 infection. Gastroenterology 144:402-413.e12
Wilkins, Courtney; Woodward, Jessica; Lau, Daryl T-Y et al. (2013) IFITM1 is a tight junction protein that inhibits hepatitis C virus entry. Hepatology 57:461-9

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