Hepatitis C virus cell entry: role of lipoproteins and cellular receptors

ABSTRACT Intracellular infectious hepatitis C virus (HCV) particles display a distinctly higher buoyant density than do secreted virus particles, suggesting that the characteristic low density of extracellular HCV particles is acquired during viral egress. We took advantage of this difference to examine the determinants of assembly, maturation, degradation, and egress of infectious HCV particles. The results demonstrate that HCV assembly and maturation occur in the endoplasmic reticulum (ER) and post-ER compartments, respectively, and that both depend on microsomal transfer protein and apolipoprotein B, in a manner that parallels the formation of very-low-density lipoproteins (VLDL). In addition, they illustrate that only low-density particles are efficiently secreted and that immature particles are actively degraded, in a proteasome-independent manner, in a post-ER compartment of the cell. These results suggest that by coopting the VLDL assembly, maturation, degradation, and secretory machinery of the cell, HCV acquires its hepatocyte tropism and, by mimicry, its tendency to persist.

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Hepatitis C virus entry into the hepatocyte

Open Life Sciences ◽

10.2478/s11535-011-0076-y ◽

2011 ◽

Vol 6 (6) ◽

pp. 933-945 ◽

Cited By ~ 3

Author(s):

Sandrine Belouzard ◽

Laurence Cocquerel ◽

Jean Dubuisson

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Current Knowledge ◽

Virus Entry ◽

Low Density Lipoprotein ◽

Scavenger Receptor ◽

Density Lipoprotein ◽

Surface Proteins ◽

Enveloped Virus ◽

Early Endosomes

AbstractHepatitis C virus (HCV) is a small enveloped virus with a positive stranded RNA genome belonging to the Flaviviridae family. The virion has the unique ability of forming a complex with lipoproteins, which is known as the lipoviroparticle. Lipoprotein components as well as the envelope proteins, E1 and E2, play a key role in virus entry into the hepatocyte. HCV entry is a complex multistep process involving sequential interactions with several cell surface proteins. The virus relies on glycosaminoglycans and possibly the low-density lipoprotein receptors to attach to cells. Furthermore, four specific entry factors are involved in the following steps which lead to virus internalization and fusion in early endosomes. These molecules are the scavenger receptor SRB1, tetraspanin CD81 and two tight junction proteins, Claudin-1 and Occludin. Although they are essential to HCV entry, the precise role of these molecules is not completely understood. Finally, hepatocytes are highly polarized cells and which likely affects the entry process. Our current knowledge on HCV entry is summarized in this review.

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Identification of Interactions in the E1E2 Heterodimer of Hepatitis C Virus Important for Cell Entry

Journal of Biological Chemistry ◽

10.1074/jbc.m110.213942 ◽

2011 ◽

Vol 286 (27) ◽

pp. 23865-23876 ◽

Cited By ~ 25

Author(s):

Guillemette Maurin ◽

Judith Fresquet ◽

Ophélia Granio ◽

Czeslaw Wychowski ◽

François-Loïc Cosset ◽

...

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Conformational Changes ◽

Transmembrane Domain ◽

Cell Entry ◽

Site Directed Mutagenesis ◽

Terminal Part ◽

Conserved Domains ◽

Biochemical Analyses

Several conserved domains critical for E1E2 assembly and hepatitis C virus entry have been identified in E1 and E2 envelope glycoproteins. However, the role of less conserved domains involved in cross-talk between either glycoprotein must be defined to fully understand how E1E2 undergoes conformational changes during cell entry. To characterize such domains and to identify their functional partners, we analyzed a set of intergenotypic E1E2 heterodimers derived from E1 and E2 of different genotypes. The infectivity of virions indicated that Con1 E1 did not form functional heterodimers when associated with E2 from H77. Biochemical analyses demonstrated that the reduced infectivity was not related to alteration of conformation and incorporation of Con1 E1/H77 E2 heterodimers but rather to cell entry defects. Thus, we generated chimeric E1E2 glycoproteins by exchanging different domains of each protein in order to restore functional heterodimers. We found that both the ectodomain and transmembrane domain of E1 influenced infectivity. Site-directed mutagenesis highlighted the role of amino acids 359, 373, and 375 in transmembrane domain in entry. In addition, we identified one domain involved in entry within the N-terminal part of E1, and we isolated a motif at position 219 that is critical for H77 function. Interestingly, using additional chimeric E1E2 complexes harboring substitutions in this motif, we found that the transmembrane domain of E1 acts as a partner of this motif. Therefore, we characterized domains of E1 and E2 that have co-evolved inside a given genotype to optimize their interactions and allow efficient entry.

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Oxidized low-density lipoprotein inhibits hepatitis C virus cell entry in human hepatoma cells

Hepatology ◽

10.1002/hep.21139 ◽

2006 ◽

Vol 43 (5) ◽

pp. 932-942 ◽

Cited By ~ 96

Author(s):

Thomas von Hahn ◽

Brett D. Lindenbach ◽

Agnès Boullier ◽

Oswald Quehenberger ◽

Matthew Paulson ◽

...

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Low Density Lipoprotein ◽

Density Lipoprotein ◽

Hepatoma Cells ◽

Cell Entry ◽

Low Density ◽

Human Hepatoma ◽

Oxidized Low Density Lipoprotein ◽

Human Hepatoma Cells

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Structural characterization of the Hepatitis C Virus E2 glycoprotein: computational and experimental approaches

10.7287/peerj.preprints.1634v1 ◽

2016 ◽

Author(s):

Daniela Barone ◽

Nicole Balasco ◽

Ida Autiero ◽

Luigi Vitagliano

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Envelope Glycoprotein ◽

Current Knowledge ◽

Host Cells ◽

Global Dynamics ◽

Dynamic Features ◽

Virus Envelope ◽

Structural Dynamic ◽

E2 Glycoprotein

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. Although effective therapeutic approaches, based on specific inhibitors of HCV proteins NS3/4A and NS5B, have been recently discovered, their use is limited by the elevated costs of these drugs. Currently, there is neither an effective immune globulin for prophylaxis nor a vaccine for the prevention of hepatitis C. A particularly attracting target is represented by the immunogenic E2 glycoprotein, a key factor for HCV entry in host cells. This protein has been the subject of recent structural studies that have greatly expand our current knowledge of HCV pathogenicity (Khan et al. 2015; Khan et al. 2014; Kong et al. 2013). In this framework, we have recently undertaken studies aimed at evaluating the potential of some regions of the protein as vaccine candidates (Sandomenico et al. 2015, under review). We here investigated the structural/dynamic features of the E2 protein, whose structure has been recently solved by two independent groups in complex with antibodies. Molecular dynamics simulations carried out on the protein core provided interesting information on both global dynamics of the protein and on local features of important regions. Moreover, a combined experimental/computational analysis shows that the epitope I region (residues 412-422) is endowed with an elevated structural versatility. Collectively these findings provide useful information for future studies aimed at designing anti-HCV vaccines.ReferencesKhan AG, Miller MT, and Marcotrigiano J. 2015. HCV glycoprotein structures: what to expect from the unexpected. Current opinion in virology 12:53-58. 10.1016/j.coviro.2015.02.004 Khan AG, Whidby J, Miller MT, Scarborough H, Zatorski AV, Cygan A, Price AA, Yost SA, Bohannon CD, Jacob J, Grakoui A, and Marcotrigiano J. 2014. Structure of the core ectodomain of the hepatitis C virus envelope glycoprotein 2. Nature 509:381-384. 10.1038/nature13117 Kong L, Giang E, Nieusma T, Kadam RU, Cogburn KE, Hua Y, Dai X, Stanfield RL, Burton DR, Ward AB, Wilson IA, and Law M. 2013. Hepatitis C virus E2 envelope glycoprotein core structure. Science 342:10901094. 10.1126/science.1243876

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Structural characterization of the Hepatitis C Virus E2 glycoprotein: computational and experimental approaches

10.7287/peerj.preprints.1634 ◽

2016 ◽

Author(s):

Daniela Barone ◽

Nicole Balasco ◽

Ida Autiero ◽

Luigi Vitagliano

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Envelope Glycoprotein ◽

Current Knowledge ◽

Host Cells ◽

Global Dynamics ◽

Dynamic Features ◽

Virus Envelope ◽

Structural Dynamic ◽

E2 Glycoprotein

Hepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. Although effective therapeutic approaches, based on specific inhibitors of HCV proteins NS3/4A and NS5B, have been recently discovered, their use is limited by the elevated costs of these drugs. Currently, there is neither an effective immune globulin for prophylaxis nor a vaccine for the prevention of hepatitis C. A particularly attracting target is represented by the immunogenic E2 glycoprotein, a key factor for HCV entry in host cells. This protein has been the subject of recent structural studies that have greatly expand our current knowledge of HCV pathogenicity (Khan et al. 2015; Khan et al. 2014; Kong et al. 2013). In this framework, we have recently undertaken studies aimed at evaluating the potential of some regions of the protein as vaccine candidates (Sandomenico et al. 2015, under review). We here investigated the structural/dynamic features of the E2 protein, whose structure has been recently solved by two independent groups in complex with antibodies. Molecular dynamics simulations carried out on the protein core provided interesting information on both global dynamics of the protein and on local features of important regions. Moreover, a combined experimental/computational analysis shows that the epitope I region (residues 412-422) is endowed with an elevated structural versatility. Collectively these findings provide useful information for future studies aimed at designing anti-HCV vaccines.ReferencesKhan AG, Miller MT, and Marcotrigiano J. 2015. HCV glycoprotein structures: what to expect from the unexpected. Current opinion in virology 12:53-58. 10.1016/j.coviro.2015.02.004 Khan AG, Whidby J, Miller MT, Scarborough H, Zatorski AV, Cygan A, Price AA, Yost SA, Bohannon CD, Jacob J, Grakoui A, and Marcotrigiano J. 2014. Structure of the core ectodomain of the hepatitis C virus envelope glycoprotein 2. Nature 509:381-384. 10.1038/nature13117 Kong L, Giang E, Nieusma T, Kadam RU, Cogburn KE, Hua Y, Dai X, Stanfield RL, Burton DR, Ward AB, Wilson IA, and Law M. 2013. Hepatitis C virus E2 envelope glycoprotein core structure. Science 342:10901094. 10.1126/science.1243876

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An Interplay between Hypervariable Region 1 of the Hepatitis C Virus E2 Glycoprotein, the Scavenger Receptor BI, and High-Density Lipoprotein Promotes both Enhancement of Infection and Protection against Neutralizing Antibodies

Journal of Virology ◽

10.1128/jvi.79.13.8217-8229.2005 ◽

2005 ◽

Vol 79 (13) ◽

pp. 8217-8229 ◽

Cited By ~ 217

Author(s):

Birke Bartosch ◽

Géraldine Verney ◽

Marlène Dreux ◽

Peggy Donot ◽

Yoann Morice ◽

...

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Neutralizing Antibodies ◽

Scavenger Receptor ◽

Hypervariable Region ◽

Density Lipoprotein ◽

Cell Entry ◽

Scavenger Receptor Bi ◽

E2 Glycoprotein ◽

Hypervariable Region 1

ABSTRACT Hepatitis C virus (HCV) circulates in the bloodstream in different forms, including complexes with immunoglobulins and/or lipoproteins. To address the significance of such associations, we produced or treated HCV pseudoparticles (HCVpp), a valid model of HCV cell entry and its inhibition, with naïve or patient-derived sera. We demonstrate that infection of hepatocarcinoma cells by HCVpp is increased more than 10-fold by human serum factors, of which high-density lipoprotein (HDL) is a major component. Infection enhancement requires scavenger receptor BI, a molecule known to mediate HDL uptake into cells as well as HCVpp entry, and involves conserved amino acid positions in hypervariable region 1 (HVR1) of the E2 glycoprotein. Additionally, we show that the interaction with human serum or HDL, but not with low-density lipoprotein, leads to the protection of HCVpp from neutralizing antibodies, including monoclonal antibodies and antibodies present in patient sera. Finally, the deletion or mutation of HVR1 in HCVpp abolishes infection enhancement and leads to increased sensitivity to neutralizing antibodies/sera compared to that of parental HCVpp. Altogether, these results assign to HVR1 new roles which are complementary in helping HCV to survive within its host. Besides immune escape by mutation, HRV1 can mediate the enhancement of cell entry and the protection of virions from neutralizing antibodies. By preserving a balance between these functions, HVR1 may be essential for the viral persistence of HCV.

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