scholarly journals The Ubiquitin-Specific Protease 18 Promotes Hepatitis C Virus Production by Increasing Viral Infectivity

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Yujia Li ◽  
Max Xuezhong Ma ◽  
Bo Qin ◽  
Liang-Tzung Lin ◽  
Christopher D. Richardson ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Entry ◽  
Virus Production ◽  
Type I ◽  
Viral Infectivity ◽  
Wild Type ◽  
Cellular Environment ◽  
Specific Protease ◽  
Ubiquitin Specific Protease

Background and Aims. Ubiquitin-specific protease 18 (USP18) is involved in immunoregulation and response to interferon- (IFN-) based treatment in patients chronically infected with hepatitis C virus (HCV). We investigated whether and how its upregulation alters HCV infection. Methods. Overexpression of wild-type (USP18 WT) or catalytically inactive mutant (USP18 C64S) USP18 was examined for effects on HCV replication in the absence and presence of IFNα or IFNλ using both the HCV-infective model and replicon cells. The IFN signaling pathway was assessed via STAT1 phosphorylation (western blot) and downstream ISG expression (real-time PCR). Mechanistic roles were sought by quantifying microRNA-122 levels and J6/JFH1 infectivity of Huh7.5 cells. Results. We found that overexpression of either USP18 WT or USP18 C64S stimulated HCV production and blunted the anti-HCV effect of IFNα and IFNλ in the infective model but not in the replicon system. Overexpressed USP18 showed no effect on Jak/STAT signaling nor on microRNA-122 expression. However, USP18 upregulation markedly increased J6/JFH1 infectivity and promoted the expression of the key HCV entry factor CD81 on Huh7.5 cells. Conclusions. USP18 stimulates HCV production and blunts the effect of both type I and III IFNs by fostering a cellular environment characterized by upregulation of CD81, promoting virus entry and infectivity.

scholarly journals Role of Scavenger Receptor Class B Type I in Hepatitis C Virus Entry: Kinetics and Molecular Determinants

2009 ◽  
Vol 84 (1) ◽  
pp. 34-43 ◽  
Author(s):  
Maria Teresa Catanese ◽  
Helenia Ansuini ◽  
Rita Graziani ◽  
Thierry Huby ◽  
Martine Moreau ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Entry ◽  
Scavenger Receptor ◽  
Specific Protein ◽  
Early Event ◽  
Type I ◽  
Direct Role ◽  
Scavenger Receptor Class ◽  
Class B

ABSTRACT Scavenger receptor class B type I (SR-BI) is an essential receptor for hepatitis C virus (HCV) and a cell surface high-density-lipoprotein (HDL) receptor. The mechanism of SR-BI-mediated HCV entry, however, is not clearly understood, and the specific protein determinants required for the recognition of the virus envelope are not known. HCV infection is strictly linked to lipoprotein metabolism, and HCV virions may initially interact with SR-BI through associated lipoproteins before subsequent direct interactions of the viral glycoproteins with SR-BI occur. The kinetics of inhibition of cell culture-derived HCV (HCVcc) infection with an anti-SR-BI monoclonal antibody imply that the recognition of SR-BI by HCV is an early event of the infection process. Swapping and single-substitution mutants between mouse and human SR-BI sequences showed reduced binding to the recombinant soluble E2 (sE2) envelope glycoprotein, thus suggesting that the SR-BI interaction with the HCV envelope is likely to involve species-specific protein elements. Most importantly, SR-BI mutants defective for sE2 binding, although retaining wild-type activity for receptor oligomerization and binding to the physiological ligand HDL, were impaired in their ability to fully restore HCVcc infectivity when transduced into an SR-BI-knocked-down Huh-7.5 cell line. These findings suggest a specific and direct role for the identified residues in binding HCV and mediating virus entry. Moreover, the observation that different regions of SR-BI are involved in HCV and HDL binding supports the hypothesis that new therapeutic strategies aimed at interfering with virus/SR-BI recognition are feasible.

scholarly journals Disrupting the association of hepatitis C virus core protein with lipid droplets correlates with a loss in production of infectious virus

2007 ◽  
Vol 88 (8) ◽  
pp. 2204-2213 ◽  
Author(s):  
Steeve Boulant ◽  
Paul Targett-Adams ◽  
John McLauchlan
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Lipid Droplet ◽  
Lipid Droplets ◽  
Core Protein ◽  
Virus Production ◽  
Endoplasmic Reticulum Membrane ◽  
Wild Type ◽  
The Core ◽  
Phenylalanine Residue

In infected cells, hepatitis C virus (HCV) core protein is targeted to lipid droplets, which serve as intracellular storage organelles. Using a tissue culture system to generate infectious HCV, we have shown that the coating of lipid droplets by the core protein occurs in a time-dependent manner and coincides with higher rates of virus production. At earlier times, the protein was located at punctate sites in close proximity to the edge of lipid droplets. Investigations by using Z-stack analysis have shown that many lipid droplets contained a single punctate site that could represent positions where core transfers from the endoplasmic reticulum membrane to droplets. The effects of lipid droplet association on virus production were studied by introducing mutations into the domain D2, the C-terminal region of the core protein necessary for droplet attachment. Alteration of a phenylalanine residue that was crucial for lipid droplet association generated an unstable form of the protein that could only be detected in the presence of a proteasome inhibitor. Moreover, converting two proline residues in D2 to alanines blocked coating of lipid droplets by core, although the protein was directed to punctate sites that were indistinguishable from those observed at early times for wild-type core protein. Neither of these virus mutants gave rise to virus progeny. By contrast, mutation at a cysteine residue positioned 2 aa upstream of the phenylalanine residue did not affect lipid droplet localization and produced wild-type levels of infectious progeny. Taken together, our findings indicate that lipid droplet association by core is connected to virus production.

scholarly journals Regulation of Hepatitis C Virus Translation and Infectious Virus Production by the MicroRNA miR-122

2010 ◽  
Vol 84 (13) ◽  
pp. 6615-6625 ◽  
Author(s):  
Rohit K. Jangra ◽  
MinKyung Yi ◽  
Stanley M. Lemon
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Infectious Virus ◽  
Virus Production ◽  
Hcv Rna ◽  
Wild Type ◽  
Entry Site ◽  
Internal Ribosome Entry ◽  
High Virus ◽  
In Cells

ABSTRACT miR-122 is a liver-specific microRNA that positively regulates hepatitis C virus (HCV) RNA abundance and is essential for production of infectious HCV. Using a genetic approach, we show that its ability to enhance yields of infectious virus is dependent upon two miR-122-binding sites near the 5′ end of the HCV genome, S1 and S2. Viral RNA with base substitutions in both S1 and S2 failed to produce infectious virus in transfected cells, while virus production was rescued to near-wild-type levels in cells supplemented with a complementary miR-122 mutant. A comparison of mutants with substitutions in only one site revealed S1 to be dominant, as an S2 but not S1 mutant produced high virus yields in cells supplemented with wild-type miR-122. Translation of HCV RNA was reduced over 50% by mutations in either S1 or S2 and was partially rescued by transfection of the complementary miR-122 mutant. Unlike the case for virus replication, however, both sites function equally in regulating translation. We conclude that miR-122 promotes replication by binding directly to both sites in the genomic RNA and, at least in part, by stimulating internal ribosome entry site (IRES)-mediated translation. However, a comparison of the replication capacities of the double-binding-site mutant and an IRES mutant with a quantitatively equivalent defect in translation suggests that the decrement in translation associated with loss of miR-122 binding is insufficient to explain the profound defect in virus production by the double mutant. miR-122 is thus likely to act at an additional step in the virus life cycle.

scholarly journals High Density Lipoproteins Facilitate Hepatitis C Virus Entry through the Scavenger Receptor Class B Type I

2005 ◽  
Vol 280 (9) ◽  
pp. 7793-7799 ◽  
Author(s):  
Cécile Voisset ◽  
Nathalie Callens ◽  
Emmanuelle Blanchard ◽  
Anne Op De Beeck ◽  
Jean Dubuisson ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Virus Entry ◽  
Scavenger Receptor ◽  
High Density ◽  
High Density Lipoproteins ◽  
Type I ◽  
Scavenger Receptor Class ◽  
Class B

scholarly journals Basic Residues in Hypervariable Region 1 of Hepatitis C Virus Envelope Glycoprotein E2 Contribute to Virus Entry

2005 ◽  
Vol 79 (24) ◽  
pp. 15331-15341 ◽  
Author(s):  
Nathalie Callens ◽  
Yann Ciczora ◽  
Birke Bartosch ◽  
Ngoc Vu-Dac ◽  
François-Loïc Cosset ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Envelope Glycoprotein ◽  
Virus Entry ◽  
Hypervariable Region ◽  
High Density Lipoproteins ◽  
Type I ◽  
Amino Acid Variability ◽  
Charged Residues ◽  
Glycoprotein E2

ABSTRACT The N terminus of hepatitis C virus (HCV) envelope glycoprotein E2 contains a hypervariable region (HVR1) which has been proposed to play a role in viral entry. Despite strong amino acid variability, HVR1 is globally basic, with basic residues located at specific sequence positions. Here we show by analyzing a large number of HVR1 sequences that the frequency of basic residues at each position is genotype dependent. We also used retroviral pseudotyped particles (HCVpp) harboring genotype 1a envelope glycoproteins to study the role of HVR1 basic residues in entry. Interestingly, HCVpp infectivity globally increased with the number of basic residues in HVR1. However, a shift in position of some charged residues also modulated HCVpp infectivity. In the absence of basic residues, infectivity was reduced to the same level as that of a mutant deleted of HVR1. We also analyzed the effect of these mutations on interactions with some potential HCV receptors. Recognition of CD81 was not affected by changes in the number of charged residues, and we did not find a role for heparan sulfates in HCVpp entry. The involvement of the scavenger receptor class B type I (SR-BI) was indirectly analyzed by measuring the enhancement of infectivity of the mutants in the presence of the natural ligand of SR-BI, high-density lipoproteins (HDL). However, no correlation between the number of basic residues within HVR1 and HDL enhancement effect was observed. Despite the lack of evidence of the involvement of known potential receptors, our results demonstrate that the presence of basic residues in HVR1 facilitates virus entry.

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