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

Binder, Marco; Kochs, Georg; Bartenschlager, Ralf; Lohmann, Volker

doi:10.1002/hep.21829

Cited by 104 publications

(99 citation statements)

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“…Virus particles were then pelleted by ultracentrifugation for 2 h at 100 000 Â g (RCF max) through a 25% sucrose cushion and viral RNA was extracted using the NucleoSpin RNA II kit (Macherey-Nagel, Düren, Germany) according to the manufacturer's recommendations. HCV genome length positive-and negative-sense RNA were prepared by in-vitro transcription as described previously [31]. All RNA preparations were quantified with the Qubit Fluorometer (Invitrogen, Karlsruhe, Germany), using the Quant-iT RNA Assay Kit (Invitrogen).…”

Section: Preparation Of Rnamentioning

confidence: 99%

“…Huh7.5 cells, expressing functional RIG-I were generated as described previously [31], MDA5-expressing Huh7.5 cells were generated accordingly. In total, 1.5 Â 10 5 HEK293 or Huh-7.5 cells, a clonal variant of the human hepatoma cell line Huh-7, were plated in DMEM containing 10% FBS per well of a 24-well culture plate.…”

Section: Reporter Assaysmentioning

confidence: 99%

“…Importantly, double-stranded in-vitro transcribed RNA-induced TNF-a secretion was dependent on the adaptor molecule Cardif. Additionally, we generated Huh7.5-based stable cell lines expressing functional RIG-I and MDA5, respectively [31]. Cells were transfected with a reporter plasmid indicating IRF3 activation.…”

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Bacterial RNA is recognized by different sets of immunoreceptors

et al. 2009

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Innate immunity recognizes microbial nucleic acids by endosomal TLR and cytosolic recognition systems. Despite increasing knowledge on the properties of nucleic acid recognition for viral RNA and bacterial DNA, little is known about the immunogenicity of prokaryotic RNA. Here we show that bacterial RNA is a potent trigger for type-I IFN secretion in human PBMC. Activation of human plasmacytoid dendritic cells was dependent on endosomal maturation and could be blocked by a TLR7-specific inhibitor. Murine plasmacytoid dendritic cells from TLR7-deficient mice were unresponsive to bacterial RNA. Surprisingly, in myeloid DC, TLR were dispensable for TNF-a and IL-12 induction by bacterial RNA. Even non-immune stroma cells were able to mount a NF-jB response upon triggering with bacterial RNA. Retinoic-acid inducible gene I and melanoma-differentiation-associated gene 5 could be ruled out to be responsible for this reactivity. Although the inflammasome adaptor protein, apoptosis-associated speck-like protein, and a functional type-I IFN receptor were necessary for IL-1b secretion in myeloid DC, these proteins were dispensable for TNF-a and IL-12 induction by cytosolic bacterial RNA. Our results show that besides of activation of TLR7 and inflammasomes, bacterial RNA activates additional cytosolic receptors similarly as has been reported for recognition of bacterial DNA.Key words: Host defense . Immunology . Inflammation IntroductionInnate immunity relies on germline-encoded PRR, which sense conserved microbial structures of non-host origin. The bestdescribed class of PRR is the TLR. Most TLR sense pathogen components on the cell surface but a subset of TLR (TLR3,7, 8 and 9) have been shown to detect nucleic acids in the endosomal compartment [1][2][3]. Besides unmethylated CpG-DNA, which is the ligand for TLR9 [4], viral RNA was identified as a ligand for nucleic acid detecting TLR. TLR3 detects double-stranded RNA [5]. RNA-oligonucleotides as well as viral RNA are also recognized by TLR7 [6,7], especially in plasmacytoid dendritic cells (pDC). The quality and the extent of nucleotide modifications are critical for recognition by these receptors [8]. Importantly, host-derived RNA shows a much higher frequency of RNA modifications than RNA derived from prokaryotic sources [8]. Nucleic acid modifications therefore represent a structural feature, which enables the immune system to distinguish self from non-self RNA. Additionally, GU-and U-rich sequence motives were identified to play a role in TLR7-and TLR8-mediated recognition [6,9,10]. In general, TLR triggering in innate immune cells results in a strong NF-kB response. Exceptionally, TLR 7 and 9 signaling in pDC also leads to an IFN-regulatory factor 7 (IRF7) activation, resulting in type-I IFN secretion [11].The cytosolic RNA helicases retinoic-acid inducible gene I (RIG-I) and melanoma-differentiation-associated gene 5 (MDA5) A third class of innate immune receptors is the cytosolic NODlike receptors. Particularly, NACHT-, LRR-and pyrin domaincontaining protein 3 (...

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Section: Preparation Of Rnamentioning

confidence: 99%

Section: Reporter Assaysmentioning

confidence: 99%

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Bacterial RNA is recognized by different sets of immunoreceptors

et al. 2009

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Section: In Vitro Experimental Models: Insight Into Innate Immune Resmentioning

confidence: 99%

“…This block might be relevant to counteract the antiviral response triggered by the HCV RNA genome that was reported to be a potent activator of RIG-I (Saito et al, 2008b). However, others have found that the HCV genome is a rather weak inducer of IFNs arguing that this poor induction augments the block imposed by the viral protease (Binder et al, 2007).While the block of the RIG-I and TLR-3 pathway by the NS3/4A protease has been observed consistently, contradicting reports exist as to whether HCV interferes with the antiviral effect exerted by IFNs. Several studies described a partial block of Jak/Stat signalling in transgenic mice expressing HCV proteins or cells harbouring a genomic HCV replicon (Blindenbacher et al, 2003;Luquin et al, 2007), whereas HCV replication in the replicon system or in HCVcc-infected cells still is highly sensitive to treatment with type I, II or III IFNs (Frese et al, 2001(Frese et al, , 2002Marcello et al, 2006).…”

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Experimental models to study the immunobiology of hepatitis C virus

Lohmann

Bartenschlager

et al. 2010

Journal of General Virology

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Effective host immune responses are essential for the control of hepatitis C virus (HCV) infection and persistence of HCV has indeed been attributed to their failure. In recent years, several in vitro and in vivo experimental models have allowed studies of host immune responses against HCV. Numerous observations derived from these models have improved our understanding of the mechanisms responsible for the host's ability to clear the virus as well as of the mechanisms responsible for the host's failure to control HCV replication. Importantly, several findings obtained with these model systems have been confirmed in studies of acutely or chronically HCV-infected individuals. Collectively, several mechanisms are used by HCV to escape host immune responses, such as poor induction of the innate immune response and escaping/impairing adaptive immunity. In this review, we summarize current findings from experimental models available for studies of the immune response targeting HCV and discuss the relevance of these findings for the in vivo situation in HCV-infected humans. IntroductionHepatitis C virus (HCV) is an enveloped RNA virus that belongs to the genus Hepacivirus within the family Flaviviridae. The positive-strand genome has a length of 9.6 kb and it encodes a polyprotein that is cleaved by viral and cellular proteases into 10 different proteins (reviewed by Moradpour et al., 2007). The structural proteins core, envelope protein 1 (E1) and E2 reside in the amino-terminal region of the polyprotein and they are the main constituents of infectious virus particles. The hydrophobic p7 protein together with non-structural protein 2 (NS2) are required for virion assembly. The serine-type protease residing in NS3 forms a stable complex with the NS4A cofactor and contributes to polyprotein cleavage. NS4B induces alterations of intracellular membranes, designated the membranous web, which is thought to be the site of viral RNA replication. NS5A is required for RNA replication and assembly and NS5B is the RNA-dependent RNA polymerase.HCV has a narrow host range and infects only humans and chimpanzees. It is estimated that~130 million people are persistently infected by HCV worldwide (reviewed by Shepard et al., 2005). Limited therapy options and the lack of a preventive vaccine aggravate this medical issue (reviewed by Lauer & Walker, 2001). Of note, the virus is able to establish persistence in approximately two-thirds of infected subjects and has thus become a major cause of chronic liver inflammation that can culminate in liver cirrhosis or even hepatocellular carcinoma (reviewed by Lauer & Walker, 2001). It is still not completely clear why successful immune responses allow only one-third of infected subjects to clear HCV. A major limitation when addressing this issue is the lack of an immunocompetent small animal model. Importantly, however, by using novel cell culture systems, some of these hurdles have now been overcome and first important insights into the intimate interaction between HCV and its host cell have b...

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Reverse Genetic Tools to Study Hepatitis C Virus

Ploß

2012

Reverse Genetics of RNA Viruses

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

Cited by 104 publications

References 27 publications

Bacterial RNA is recognized by different sets of immunoreceptors

Bacterial RNA is recognized by different sets of immunoreceptors

Experimental models to study the immunobiology of hepatitis C virus

Reverse Genetic Tools to Study Hepatitis C Virus

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