scholarly journals Hepatitis C Virus-Mediated Inhibition of Cathepsin S Increases Invariant-Chain Expression on Hepatocyte Surface

2012 ◽  
Vol 86 (18) ◽  
pp. 9919-9928 ◽  
Author(s):  
Hangeun Kim ◽  
Budhaditya Mazumdar ◽  
Sandip K. Bose ◽  
Keith Meyer ◽  
Adrian M. Di Bisceglie ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mhc Class Ii ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Cathepsin S ◽  
Invariant Chain ◽  
Upstream Stimulatory Factor ◽  
Hla Dr ◽  
Chronic Hcv

Hepatocytes are the main source of hepatitis C virus (HCV) replication and contain the maximum viral load in an infected person. Chronic HCV infection is characterized by weak cellular immune responses to viral proteins. Cathepsin S is a lysosomal cysteine protease and controls HLA-DR–antigen complex presentation through the degradation of the invariant chain. In this study, we examined the effect of HCV proteins on cathepsin S expression and found it to be markedly decreased in dendritic cells (DCs) exposed to HCV or in hepatocytes expressing HCV proteins. The downregulation of cathepsin S was mediated by HCV core and NS5A proteins involving inhibition of the transcription factors interferon regulatory factor 1 (IRF-1) and upstream stimulatory factor 1 (USF-1) in gamma interferon (IFN-γ)-treated hepatocytes. Inhibition of cathepsin S by HCV proteins increased cell surface expression of the invariant chain. In addition, hepatocytes stably transfected with HCV core or NS5A inhibited HLA-DR expression. Together, these results suggested that HCV has an inhibitory role on cathepsin S-mediated major histocompatibility complex (MHC) class II maturation, which may contribute to weak immunogenicity of viral antigens in chronically infected humans.

scholarly journals Hepatitis C Virus Inhibits Cell Surface Expression of HLA-DR, Prevents Dendritic Cell Maturation, and Induces Interleukin-10 Production

2008 ◽  
Vol 82 (7) ◽  
pp. 3320-3328 ◽  
Author(s):  
Kousuke Saito ◽  
Malika Ait-Goughoulte ◽  
Steven M. Truscott ◽  
Keith Meyer ◽  
Azra Blazevic ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
T Cell ◽  
Cell Surface ◽  
Immune Responses ◽  
Mhc Class Ii ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Hla Dr ◽  
Ifn Γ

ABSTRACT Hepatitis C virus (HCV) chronic infection is characterized by low-level or undetectable cellular immune responses against HCV antigens. HCV proteins have been shown to affect various intracellular events and modulate immune responses, although the precise mechanisms used to mediate these effects are not fully understood. In this study, we have examined the effect of HCV proteins on the modulation of major histocompatibility complex (MHC) class II expression and other functions important for antigen presentation in humans. Expression of an HCV1-2962 genomic clone (HCV-FL) in human fibrosarcoma cells (HT1080) inhibited gamma interferon (IFN-γ)-induced upregulation of human leukocyte antigen-DR (HLA-DR) cell surface expression. Furthermore, inhibition of promoter activities of MHC class II transactivator (CIITA), IFN-γ-activated site (GAS), and HLA-DR was observed in IFN-γ-inducible HT1080 cells expressing HCV-FL by in vitro reporter assays. Exposure of human monocyte-derived dendritic cells (DCs) to cell culture-grown HCV (HCVcc) genotype 1a (clone H77) or 2a (clone JFH1) significantly inhibited DC maturation and was associated with the production of IL-10. Furthermore, DCs exposed to HCVcc were impaired in their functional ability to stimulate antigen-specific CD4-positive (CD4+) and CD8+ T-cell responses. Taken together, our results indicated that HCV can have direct and/or indirect inhibitory effects on antigen-presenting cells, resulting in reduction of antigen-specific T-cell activation. These effects may account for or contribute to the low overall level of immunogenicity of HCV observed in chronically infected patients.

scholarly journals The Level of CD81 Cell Surface Expression Is a Key Determinant for Productive Entry of Hepatitis C Virus into Host Cells

2006 ◽  
Vol 81 (2) ◽  
pp. 588-598 ◽  
Author(s):  
George Koutsoudakis ◽  
Eva Herrmann ◽  
Stephanie Kallis ◽  
Ralf Bartenschlager ◽  
Thomas Pietschmann
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cell Surface ◽  
Surface Expression ◽  
Hcv Infection ◽  
Host Cells ◽  
Productive Infection ◽  
Cell Surface Expression ◽  
Type I ◽  
Cell Clones

ABSTRACT Recently a cell culture model supporting the complete life cycle of the hepatitis C virus (HCV) was developed. Searching for host cell determinants involved in the HCV replication cycle, we evaluated the efficiency of virus propagation in different Huh-7-derived cell clones. We found that Huh-7.5 cells and Huh7-Lunet cells, two former replicon cell clones that had been generated by removal of an HCV replicon by inhibitor treatment, supported comparable levels of RNA replication and particle production, whereas virus spread was severely impaired in the latter cells. Analysis of cell surface expression of CD81 and scavenger receptor class B type I (SR-BI), two molecules previously implicated in HCV entry, revealed similar expression levels for SR-BI, while CD81 surface expression was much higher on Huh-7.5 cells than on Huh7-Lunet cells. Ectopic expression of CD81 in Huh7-Lunet cells conferred permissiveness for HCV infection to a level comparable to that for Huh-7.5 cells. Modulation of CD81 cell surface density in Huh-7.5 cells by RNA interference indicated that a certain amount of this molecule (∼7 × 104 molecules per cell) is required for productive infection with a low dose of HCV. Consistent with this, we show that susceptibility to HCV infection depends on a critical quantity of CD81 molecules. While infection is restricted in cells expressing very small amounts of CD81, susceptibility rapidly rises within a narrow range of CD81 levels, reaching a plateau where higher expression does not further increase the efficiency of infection. Together these data indicate that a high density of cell surface-exposed CD81 is a key determinant for productive HCV entry into host cells.

scholarly journals Residues in a Highly Conserved Claudin-1 Motif Are Required for Hepatitis C Virus Entry and Mediate the Formation of Cell-Cell Contacts

2009 ◽  
Vol 83 (11) ◽  
pp. 5477-5484 ◽  
Author(s):  
Lisa Cukierman ◽  
Laurent Meertens ◽  
Claire Bertaux ◽  
Francis Kajumo ◽  
Tatjana Dragic
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protein Interactions ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Membrane Domains ◽  
Cell Contacts ◽  
Functional Roles ◽  
Critical Residues ◽  
Cell Cell

ABSTRACT Claudin-1, a component of tight junctions between liver hepatocytes, is a hepatitis C virus (HCV) late-stage entry cofactor. To investigate the structural and functional roles of various claudin-1 domains in HCV entry, we applied a mutagenesis strategy. Putative functional intracellular claudin-1 domains were not important. However, we identified seven novel residues in the first extracellular loop that are critical for entry of HCV isolates drawn from six different subtypes. Most of the critical residues belong to the highly conserved claudin motif W30-GLW51-C54-C64. Alanine substitutions of these residues did not impair claudin-1 cell surface expression or lateral protein interactions within the plasma membrane, including claudin-1-claudin-1 and claudin-1-CD81 interactions. However, these mutants no longer localized to cell-cell contacts. Based on our observations, we propose that cell-cell contacts formed by claudin-1 may generate specialized membrane domains that are amenable to HCV entry.

Cell surface expression of functional hepatitis C virus E1 and E2 glycoproteins

FEBS Letters ◽  
2003 ◽  
Vol 546 (2-3) ◽  
pp. 385-390 ◽  
Author(s):  
Heidi E. Drummer ◽  
Anne Maerz ◽  
Pantelis Poumbourios
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cell Surface ◽  
Surface Expression ◽  
Cell Surface Expression

scholarly journals Expressionof Unmodified Hepatitis C Virus Envelope Glycoprotein-Coding SequencesLeads to Cryptic Intron Excision and Cell Surface Expression of E1/E2Heterodimers Comprising Full-Length and Partially DeletedE1

2003 ◽  
Vol 77 (24) ◽  
pp. 13418-13424 ◽  
Author(s):  
Julie Dumonceaux ◽  
Emmanuel G. Cormier ◽  
Francis Kajumo ◽  
Gerald P. Donovan ◽  
Jayanta Roy-Chowdhury ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Virus ◽  
Expression System ◽  
Surface Expression ◽  
Viral Envelope ◽  
Cell Surface Expression ◽  
Envelope Glycoproteins ◽  
Virus Envelope ◽  
Positive Strand Rna

ABSTRACT Hepatitis C virus (HCV) is a positive-strand RNA virus that replicates exclusively in the cytoplasm of infected cells. The viral envelope glycoproteins, E1 and E2, appear to be retained in the endoplasmic reticulum, where viral budding is thought to occur. Surprisingly, we found that the expression system used to generate HCV envelope glycoproteins influences their subcellular localization and processing. These findings have important implications for optimizing novel HCV fusion and entry assays as well as for budding and virus particle formation.

scholarly journals Functional Analysis of Cell Surface-Expressed Hepatitis C Virus E2 Glycoprotein

1999 ◽  
Vol 73 (8) ◽  
pp. 6782-6790 ◽  
Author(s):  
Mike Flint ◽  
Joanne M. Thomas ◽  
Catherine M. Maidens ◽  
Christine Shotton ◽  
Shoshana Levy ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cell Surface ◽  
Influenza A ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Soluble Form ◽  
Fusion Peptides ◽  
Hydrophobic Amino Acids ◽  
Anchor Sequence

ABSTRACT Hepatitis C virus (HCV) glycoproteins E1 and E2, when expressed in eukaryotic cells, are retained in the endoplasmic reticulum (ER). C-terminal truncation of E2 at residue 661 or 715 (position on the polyprotein) leads to secretion, consistent with deletion of a proposed hydrophobic transmembrane anchor sequence. We demonstrate cell surface expression of a chimeric glycoprotein consisting of E2 residues 384 to 661 fused to the transmembrane and cytoplasmic domains of influenza A virus hemagglutinin (HA), termed E2661-HATMCT. The E2661-HATMCT chimeric glycoprotein was able to bind a number of conformation-dependent monoclonal antibodies and a recombinant soluble form of CD81, suggesting that it was folded in a manner comparable to “native” E2. Furthermore, cell surface-expressed E2661-HATMCT demonstrated pH-dependent changes in antigen conformation, consistent with an acid-mediated fusion mechanism. However, E2661-HATMCT was unable to induce cell fusion of CD81-positive HEK cells after neutral- or low-pH treatment. We propose that a stretch of conserved, hydrophobic amino acids within the E1 glycoprotein, displaying similarities to flavivirus and paramyxovirus fusion peptides, may constitute the HCV fusion peptide. We demonstrate that influenza virus can incorporate E2661-HATMCT into particles and discuss experiments to address the relevance of the E2-CD81 interaction for HCV attachment and entry.

scholarly journals The transmembrane domain and luminal C-terminal region independently support invariant chain trimerization and assembly with MHCII into nonamers

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Maryse Cloutier ◽  
Jean-Simon Fortin ◽  
Jacques Thibodeau
Keyword(s):  
Transmembrane Domain ◽  
Surface Expression ◽  
Terminal Region ◽  
Site Directed Mutagenesis ◽  
Cell Surface Expression ◽  
Invariant Chain ◽  
Multifunctional Protein ◽  
Hla Dr ◽  
Antigen Presenting ◽  
Order Structures

Abstract Background Invariant chain (CD74, Ii) is a multifunctional protein expressed in antigen presenting cells. It assists the ER exit of various cargos and serves as a receptor for the macrophage migration inhibitory factor. The newly translated Ii chains trimerize, a structural feature that is not readily understood in the context of its MHCII chaperoning function. Two segments of Ii, the luminal C-terminal region (TRIM) and the transmembrane domain (TM), have been shown to participate in the trimerization process but their relative importance and impact on the assembly with MHCII molecules remains debated. Here, we addressed the requirement of these domains in the trimerization of human Ii as well as in the oligomerization with MHCII molecules. We used site-directed mutagenesis to generate series of Ii and DR mutants. These were transiently transfected in HEK293T cells to test their cell surface expression and analyse their interactions by co-immunoprecipitations. Results Our results showed that the TRIM domain is not essential for Ii trimerization nor for intracellular trafficking with MHCII molecules. We also gathered evidence that in the absence of TM, TRIM allows the formation of multi-subunit complexes with HLA-DR. Similarly, in the absence of TRIM, Ii can assemble into high-order structures with MHCII molecules. Conclusions Altogether, our data show that trimerization of Ii through either TM or TRIM sustains nonameric complex formation with MHCII molecules.

Genetic polymorphisms as the predictors of response to antiviral treatment in chronic hepatitis C virus infection

2011 ◽  
Vol 152 (22) ◽  
pp. 876-881
Author(s):  
Alajos Pár
Keyword(s):  
Chronic Hepatitis ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Genetic Polymorphisms ◽  
Chronic Hepatitis C ◽  
Genome Wide Association Study ◽  
Antiviral Treatment ◽  
Hcv Infection ◽  
Snp Analysis ◽  
Chronic Hcv

The review discusses the genetic polymorphisms involved in the pathogenesis of hepatitis C virus (HCV) infection, that may determine the outcome of disease. In this field earlier both certain major histocompatibility complex (MHC) alleles and some cytokine gene variants have also been studied. Recently, the genome-wide association study (GWAS) and targeted single nucleotide polymorphism (SNP) analysis have revealed that a variant in the promoter region of interleukin-28B (IL-28B) gene is strongly linked to viral clearance and it may be the strongest pretreatment predictor of treatment response in chronic hepatitis C. Last year it was shown that two genetic variants leading to inosine triphosphatase deficiency protect against haemolytic anemia in patients receiving ribavirin during antiviral treatment for chronic HCV infection. Orv. Hetil., 2011, 152, 876–881.

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