Hepatitis C virus escape from the interferon regulatory... : Hepatology (original) (raw)

Viral Hepatitis

Hepatitis C virus escape from the interferon regulatory factor 3 pathway by a passive and active evasion strategy

Binder, Marco1; Kochs, Georg2; Bartenschlager, Ralf1; Lohmann, Volker1*

1_Department of Molecular Virology, University of Heidelberg, Heidelberg, Germany_

2_Department of Virology, Institute for Medical Microbiology and Hygiene, University of Freiburg, Freiburg, Germany_

*Address reprint requests to: Department of Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany

Email:[email protected]

Received 27 February 2007; Accepted 22 May 2007

Published online 1 August 2007 in Wiley InterScience (www.interscience.wiley.com).

Grant sponsor: National Genome Research Network, NGFN; Grant sponsor: German Ministry for Research and Education and the “Kompetenznetz Hepatitis (Teilprojekt 13.2)”.

Potential conflict of interest: Nothing to report.

fax: (49)-6221-564570.

Abstract

Hepatitis C virus (HCV) has been known to replicate with extremely varying efficiencies in different host cells, even within different populations of a single human hepatoma cell line, termed Huh-7. Several reports have implicated the retinoic-acid inducible gene I (RIG-I)/ interferon regulatory factor 3 (IRF-3) pathway of the innate antiviral response with differences in host cell permissiveness to HCV. To investigate the general impact of the IRF-3 response onto HCV replication in cell culture, we generated an ample array of stable Huh-7 cell lines with altered IRF-3 responsiveness. Neither blocking IRF-3 activation in various host cells by expression of dominant negative RIG-I or HCV NS3/4A protease nor reconstitution of RIG-I signaling in Huh7.5, a cell clone known to be defective in this pathway, had any impact on HCV replication. Only by overexpressing constitutively active RIG-I or the signaling adaptor Cardif (also known as interferon-beta promoter stimulator 1, mitochondrial anti-viral signaling protein, or virus-induced signaling adaptor), both leading to a stimulation of the IRF-3 pathway in the absence of inducers, was HCV replication significantly inhibited. We therefore assessed the extent of RIG-I– dependent IRF-3 activation by different species of RNA, including full-length HCV genomes and HCV RNA duplexes, and observed strong induction only in response to double-stranded RNAs.

Conclusion:

Based on these findings, we propose a refined model of innate immune escape by HCV involving limited initial induction and stringent subsequent control of the IRF-3 response.

Abbreviations: aa, amino acid; ca, constitutively active; Cardif, caspase recruitment domain adaptor inducing interferon-β CR, mutated Cardif C508R; dn, dominant negative; dsRNA, double-stranded RNA; HCV, hepatitis C virus; hp, high passage; IFN, interferon; IRF-3, interferon-regulatory factor 3; ISG, interferon stimulated gene; lp, low passage; MDA5, melanoma differentiation associated protein 5; NS, nonstructural protein; poly(C), polycytidylic acid; poly(I), polyinosinic acid; poly(I:C), polyinosinic acid: polycytidylic acid duplex; RIG-I, retinoic-acid inducible gene I; RLU, relative light units; RNA, ribonucleic acid; SeV, Sendai virus; TLR, Toll-like receptor; wt, wild-type.