1
|
Moustafa S, Kassela K, Bampali M, Dovrolis N, Kakkanas A, Beloukas A, Mavromara P, Karakasiliotis I. Hepatitis C Core Protein Induces a Genotype-Specific Susceptibility of Hepatocytes to TNF-Induced Death In Vitro and In Vivo. Viruses 2022; 14:v14112521. [PMID: 36423130 PMCID: PMC9692671 DOI: 10.3390/v14112521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 11/01/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
Hepatitis C virus (HCV) core protein is a multifunctional protein that is involved in the proliferation, inflammation, and apoptosis mechanism of hepatocytes. HCV core protein genetic variability has been implicated in various outcomes of HCV pathology and treatment. In the present study, we aimed to analyze the role of the HCV core protein in tumor necrosis factor α (TNFα)-induced death under the viewpoint of HCV genetic variability. Immortalized hepatocytes (IHH), and not the Huh 7.5 hepatoma cell line, stably expressing HCV subtype 4a and HCV subtype 4f core proteins showed that only the HCV 4a core protein could increase sensitivity to TNFα-induced death. Development of two transgenic mice expressing the two different core proteins under the liver-specific promoter of transthyretin (TTR) allowed for the in vivo assessment of the role of the core in TNFα-induced death. Using the TNFα-dependent model of lipopolysaccharide/D-galactosamine (LPS/Dgal), we were able to recapitulate the in vitro results in IHH cells in vivo. Transgenic mice expressing the HCV 4a core protein were more susceptible to the LPS/Dgal model, while mice expressing the HCV 4f core protein had the same susceptibility as their littermate controls. Transcriptome analysis in liver biopsies from these transgenic mice gave insights into HCV core molecular pathogenesis while linking HCV core protein genetic variability to differential pathology in vivo.
Collapse
Affiliation(s)
- Savvina Moustafa
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, 11521 Athens, Greece
| | - Katerina Kassela
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, 11521 Athens, Greece
- Laboratory of Biology, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Maria Bampali
- Laboratory of Biology, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Nikolas Dovrolis
- Laboratory of Biology, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Athanassios Kakkanas
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, 11521 Athens, Greece
| | - Apostolos Beloukas
- National AIDS Reference Center of Southern Greece, Department of Public Health Policy, University of West Attica, 12243 Athens, Greece
- Molecular Microbiology & Immunology Lab, Department of Biomedical Sciences, University of West Attica, 11521 Athens, Greece
| | - Penelope Mavromara
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, 11521 Athens, Greece
- Department of Molecular Biology and Genetics, Democritus University of Thrace, 68100 Alexandroupolis, Greece
| | - Ioannis Karakasiliotis
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, 11521 Athens, Greece
- Laboratory of Biology, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece
- Correspondence:
| |
Collapse
|
2
|
dos Reis VP, Keller M, Schmidt K, Ulrich RG, Groschup MH. αVβ3 Integrin Expression Is Essential for Replication of Mosquito and Tick-Borne Flaviviruses in Murine Fibroblast Cells. Viruses 2021; 14:v14010018. [PMID: 35062222 PMCID: PMC8780171 DOI: 10.3390/v14010018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/17/2021] [Accepted: 12/20/2021] [Indexed: 12/16/2022] Open
Abstract
The Flavivirus genus includes a number of important viruses that are pathogenic to humans and animals and are responsible for outbreaks across the globe. Integrins, a family of heterodimeric transmembrane molecules expressed in all nucleated cells mediate critical functions of cell physiology and cell cycle. Integrins were previously postulated to be involved in flavivirus entry and to modulate flavivirus replication efficiency. In the present study, mouse embryonic fibroblasts (MEF), lacking the expression of αVβ3 integrin (MEF-αVβ3−/−), were infected with four different flaviviruses, namely yellow fever virus (YFV), West Nile virus (WNV), Usutu virus (USUV) and Langat virus (LGTV). The effects of the αVβ3 integrin absence in double-knockout MEF-αVβ3−/− on flavivirus binding, internalization and replication were compared to the respective wild-type cells. Binding to the cell surface for all four flaviviruses was not affected by the ablation of αVβ3 integrin, whereas internalization of USUV and WNV was slightly affected by the loss of αVβ3 integrin expression. Most interestingly, the deletion of αVβ3 integrin strongly impaired replication of all flaviviruses with a reduction of up to 99% on virus yields and a strong reduction on flavivirus anti-genome RNA synthesis. In conclusion, our results demonstrate that αVβ3 integrin expression in flavivirus-susceptible cell lines enhances the flavivirus replication.
Collapse
Affiliation(s)
- Vinicius Pinho dos Reis
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (V.P.d.R.); (M.K.); (R.G.U.)
- Institute for Virology, Philipps University Marburg, Hans-Meerwein-Straße 2, 35043 Marburg, Germany
| | - Markus Keller
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (V.P.d.R.); (M.K.); (R.G.U.)
| | - Katja Schmidt
- Microbiological Diagnostics, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany;
| | - Rainer Günter Ulrich
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (V.P.d.R.); (M.K.); (R.G.U.)
- Deutsches Zentrum für Infektionsforschung(DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Südufer 10, 17493 Greifswald-Insel Riems, Germany
| | - Martin Hermann Groschup
- Institute of Novel and Emerging Infectious Diseases, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Südufer 10, 17493 Greifswald-Insel Riems, Germany; (V.P.d.R.); (M.K.); (R.G.U.)
- Deutsches Zentrum für Infektionsforschung(DZIF), Partner Site Hamburg-Lübeck-Borstel-Riems, Südufer 10, 17493 Greifswald-Insel Riems, Germany
- Correspondence: ; Tel.: +49-38351-71163
| |
Collapse
|
3
|
Song X, Gao X, Wang Y, Raja R, Zhang Y, Yang S, Li M, Yao Z, Wei L. HCV Core Protein Induces Chemokine CCL2 and CXCL10 Expression Through NF-κB Signaling Pathway in Macrophages. Front Immunol 2021; 12:654998. [PMID: 34531848 PMCID: PMC8438213 DOI: 10.3389/fimmu.2021.654998] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 08/16/2021] [Indexed: 12/15/2022] Open
Abstract
HCV core protein is the first structural protein synthesized during hepatitis C virus (HCV) infection and replication. It is released from virus infected liver cells and mediates multiple functions to affect host cell response. The innate immune response is the first line of defense against viral infection. After HCV infection, Kupffer cells (KCs) which are liver macrophages play an important role in host innate immune response. Kupffer cells act as phagocytes and release different cytokines and chemokines to counter viral infection and regulate inflammation and fibrosis in liver. Earlier, we have demonstrated that HCV core protein interacts with gC1qR and activates MAPK, NF-κB and PI3K/AKT pathways in macrophages. In this study, we explored the effect of HCV core protein on CCL2 and CXCL10 expression in macrophages and the signaling pathways involved. Upon silencing of gC1qR, we observed a significant decrease expression of CCL2 and CXCL10 in macrophages in the presence of HCV core protein. Inhibiting NF-κB pathway, but not P38, JNK, ERK and AKT pathways greatly reduced the expression of CCL2 and CXCL10. Therefore, our results indicate that interaction of HCV core protein with gC1qR could induce CCL2 and CXCL10 secretion in macrophages via NF-κB signaling pathway. These findings may shed light on the understanding of how leukocytes migrate into the liver and exaggerate host-derived immune responses and may provide novel therapeutic targets in HCV chronic inflammation.
Collapse
Affiliation(s)
- Xiaotian Song
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| | - Xue Gao
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| | - Yadong Wang
- Department of Infectious Diseases, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Rameez Raja
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Yaoyu Zhang
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| | - Shulin Yang
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| | - Miao Li
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| | - Zhiyan Yao
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| | - Lin Wei
- Department of Immunology, Hebei Medical University, Shijiazhuang, China.,Key Laboratory of Immune Mechanism and Intervention on Serious Disease in Hebei Province, Shijiazhuang, China
| |
Collapse
|
4
|
Hepatitis C Virus Uses Host Lipids to Its Own Advantage. Metabolites 2021; 11:metabo11050273. [PMID: 33925362 PMCID: PMC8145847 DOI: 10.3390/metabo11050273] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 04/11/2021] [Accepted: 04/23/2021] [Indexed: 02/06/2023] Open
Abstract
Lipids and lipoproteins constitute indispensable components for living not only for humans. In the case of hepatitis C virus (HCV), the option of using the products of our lipid metabolism is “to be, or not to be”. On the other hand, HCV infection, which is the main cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma, exerts a profound influence on lipid and lipoprotein metabolism of the host. The consequences of this alternation are frequently observed as hypolipidemia and hepatic steatosis in chronic hepatitis C (CHC) patients. The clinical relevance of these changes reflects the fact that lipids and lipoprotein play a crucial role in all steps of the life cycle of HCV. The virus circulates in the bloodstream as a highly lipidated lipo-viral particle (LVP) that defines HCV hepatotropism. Thus, strict relationships between lipids/lipoproteins and HCV are indispensable for the mechanism of viral entry into hepatocytes, viral replication, viral particles assembly and secretion. The purpose of this review is to summarize the tricks thanks to which HCV utilizes host lipid metabolism to its own advantage.
Collapse
|
5
|
Shao LN, Zhou SH, Wang N, Zhang ST, Liu M. Association between the Genetic Polymorphisms of CCL2, CCL5, CCL8, CCR2, and CCR5 with Chronic Hepatitis C Virus Infection in the Chinese Han Population. Immunol Invest 2021; 51:1182-1197. [PMID: 33902378 DOI: 10.1080/08820139.2021.1916524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Background: Hepatitis C virus (HCV) infection is a global public health burden. Chronic HCV infection leads to the development of fibrosis, cirrhosis, liver cancer, and liver failure over time.Methods: A total of 250 patients with chronic HCV infection and 299 healthy blood donors were recruited. Sixteen candidate single nucleotide polymorphisms (SNPs) in chemokine (C-C motif) ligand 2 (CCL2), CCL5, CCL8, C-C chemokine receptor 2 (CCR2), and CCR5 were genotyped in all participants.Results: The rs1024610 AA genotype was significantly associated with decreased susceptibility to chronic HCV infection. Aspartate aminotransferase (AST) levels, AST/platelet ratio index, and the fibrosis 4 score were significantly lower in the CCL2 rs1024610 T allele and haplotype ATGC carriers. Moreover, expression levels of collagen IV (C-IV) and laminin (LN) were significantly higher in patients with the CCL5 rs2280788 C allele compared to the non-carriers. Similarly, the expression levels of C-IV, LN, and hyaluronic acid were significantly higher in patients with the CCL5 haplotype, TGCT. No significant differences were identified between the SNPs/haplotypes and plasma levels of CCL2, CCL5, CCL8, CCR2, and CCR5 in the healthy controls, and the rs1024610 allele alteration had no effect on CCL2 promoter activity.Conclusions: This is the first study to report an association between CCL2 rs1024610 and the risk of chronic HCV infection in the Chinese Han population. rs1024610 and ATGC haplotype in CCL2 were reasonable candidate markers of liver abnormalities. rs2280788 and TGCT haplotype in CCL5 are likely to play a significant role in liver fibrosis during chronic HCV infection.
Collapse
Affiliation(s)
| | | | - Ni Wang
- Dalian Blood Center, Dalian, Liaoning, China
| | | | - Ming Liu
- Department of Cell Biology, Dalian Medical University, Dalian, Liaoning, China
| |
Collapse
|
6
|
Shimotohno K. HCV Assembly and Egress via Modifications in Host Lipid Metabolic Systems. Cold Spring Harb Perspect Med 2021; 11:cshperspect.a036814. [PMID: 32122916 PMCID: PMC7778218 DOI: 10.1101/cshperspect.a036814] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Hepatitis C virus (HCV) proliferates by hijacking the host lipid machinery. In vitro replication systems revealed many aspects of the virus life cycle; in particular, viral utilization of host lipid metabolism during HCV proliferation. HCV interacts with lipid droplets (LDs) before starting the process of virus capsid formation at the lipid-rich endoplasmic reticulum (ER) membrane compartment. HCV buds into the ER via lipoprotein assembly and secretion. Exchangeable apolipoproteins, represented by apolipoprotein E (apoE), play pivotal roles in enhancing HCV-specific infectivity. HCV virions are likely to interact with other lipoproteins circulating in blood vessels and incorporate apolipoproteins as well as lipids. This review focuses on virus assembly and egress by briefly describing the recent advances in this area.
Collapse
|
7
|
Impact of Apo Lipoprotein E Gene Polymorphism on Hepatitis C Virus Disease Progression and Response to Direct Acting Antivirals in the Egyptian Population. HEPATITIS MONTHLY 2020. [DOI: 10.5812/hepatmon.101516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Background: Hepatitis C virus infection is a major health problem in Egypt. Apo lipoprotein E and lipid metabolism are closely associated with the life cycle of the virus and play an important role in facilitating this infection. Objectives: To identify the role of apolipoprotein E gene polymorphism on hepatitis C virus disease progression and response to direct-acting antivirals (DAAs). Methods: We included twenty patients with chronic hepatitis C virus infection (CHC) from those who failed to respond to DAAs treatment and 76 subjects from responders. Apo lipoprotein E genotypes were determined using PCR restriction enzyme fragment length polymorphism (RFLP). Results: Apolipoprotein genotype E3/E3 was prevalent in 75.9% of patients. The distribution for the rest of genotypes was 16.9%, 3.6%, 2.4% and 1.2 % for Apo E3/E4, E2/E3, E4/E4, and E2/E2 respectively. No statistically significant difference was found regarding any of the Apo E genotypes with liver cirrhosis or response to therapy. Conclusions: No significant impact for any Apo E genotypes on CHC disease severity or response to therapy with direct-acting antivirals was detected among Egyptian patients.
Collapse
|
8
|
Abstract
Apolipoprotein E (apoE) plays dual functions in the HCV life cycle by promoting HCV infection and virion assembly and production. ApoE is a structural component on the HCV envelope. It mediates HCV cell attachment through specific interactions with the cell surface receptors such as syndecan-1 (SDC-1) and SDC-2 heparan sulfate proteoglycans (HSPGs). It also interacts with NS5A and E2, resulting in an enhancement of HCV morphogenesis. It can bind HCV extracellularly and promotes HCV infection. It is critical for HCV cell-to-cell transmission and may also play a role in HCV persistence by interfering with the action of HCV-neutralizing antibodies. Other apolipoproteins particularly apoB and apoC1 were also found on the HCV envelope, but their roles in the HCV life cycle remain unclear. In the last decade, a number of genomic, immunological, structural, and cell biology methodologies have been developed and used for determining the importance of apoE in the HCV life cycle. These methods and protocols will continue to be valuable to further understand the importance and the underlying molecular mechanism of various apolipoproteins in HCV infection and pathogenesis.
Collapse
Affiliation(s)
- Luhua Qiao
- Department of Microbiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USA
| | - Guangxiang George Luo
- Department of Microbiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USA.
| |
Collapse
|
9
|
Schöbel A, Rösch K, Herker E. Functional innate immunity restricts Hepatitis C Virus infection in induced pluripotent stem cell-derived hepatocytes. Sci Rep 2018; 8:3893. [PMID: 29497123 PMCID: PMC5832748 DOI: 10.1038/s41598-018-22243-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 02/20/2018] [Indexed: 12/15/2022] Open
Abstract
Knowledge of activation and interplay between the hepatitis C virus (HCV) and the hosts’ innate immunity is essential to understanding the establishment of chronic HCV infection. Human hepatoma cell lines, widely used as HCV cell culture system, display numerous metabolic alterations and a defective innate immunity, hindering the detailed study of virus-host interactions. Here, we analysed the suitability of induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (iHLCs) as a physiologically relevant model to study HCV replication in vitro. Density gradients and triglyceride analysis revealed that iHLCs secreted very-low density lipoprotein (VLDL)-like lipoproteins, providing a putative platform for bona fide lipoviroparticles. iHLCs supported the full HCV life cycle, but in contrast to Huh7 and Huh7.5 cells, replication and viral RNA levels decreased continuously. Following HCV infection, interferon-stimulated gene (ISG)-expression significantly increased in iHLCs, whereas induction was almost absent in Huh7/7.5 cells. However, IFNα-stimulation equally induced ISGs in iHLCs and hepatoma cells. JAK-STAT pathway inhibition increased HCV replication in mature iHLCs, but not in Huh7 cells. Additionally, HCV replication levels where higher in STAT2-, but not STAT1-knockdown iHLCs. Our findings support iHLCs as a suitable model for HCV-host interaction regarding a functional innate immunity and lipoprotein synthesis.
Collapse
Affiliation(s)
- Anja Schöbel
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Kathrin Rösch
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Eva Herker
- Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Hamburg, Germany.
| |
Collapse
|
10
|
Authentic Patient-Derived Hepatitis C Virus Infects and Productively Replicates in Primary CD4 + and CD8 + T Lymphocytes In Vitro. J Virol 2018; 92:JVI.01790-17. [PMID: 29167333 DOI: 10.1128/jvi.01790-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 11/09/2017] [Indexed: 12/17/2022] Open
Abstract
Accumulated evidence indicates that immune cells can support the replication of hepatitis C virus (HCV) in infected patients and in culture. However, there is a scarcity of data on the degree to which individual immune cell types support HCV propagation and on characteristics of virus assembly. We investigated the ability of authentic, patient-derived HCV to infect in vitro two closely related but functionally distinct immune cell types, CD4+ and CD8+ T lymphocytes, and assessed the properties of the virus produced by these cells. The HCV replication system in intermittently mitogen-stimulated T cells was adapted to infect primary human CD4+ or CD8+ T lymphocytes. HCV replicated in both cell types although at significantly higher levels in CD4+ than in CD8+ T cells. Thus, the HCV RNA replicative (negative) strand was detected in CD4+ and CD8+ cells at estimated mean levels ± standard errors of the means of 6.7 × 102 ± 3.8 × 102 and 1.2 × 102 ± 0.8 × 102 copies/μg RNA, respectively (P < 0.0001). Intracellular HCV NS5a and/or core proteins were identified in 0.9% of CD4+ and in 1.2% of CD8+ T cells. Double staining for NS5a and T cell type-specific markers confirmed that transcriptionally competent virus replicated in both cell types. Furthermore, an HCV-specific protease inhibitor, telaprevir, inhibited infection in both CD4+ and CD8+ cells. The emergence of unique HCV variants and the release of HCV RNA-reactive particles with biophysical properties different from those of virions in plasma inocula suggested that distinct viral particles were assembled, and therefore, they may contribute to the pool of circulating virus in infected patients.IMPORTANCE Although the liver is the main site of HCV replication, infection of the immune system is an intrinsic characteristic of this virus independent of whether infection is symptomatic or clinically silent. Many fundamental aspects of HCV lymphotropism remain uncertain, including the degree to which different immune cells support infection and contribute to virus diversity. We show that authentic, patient-derived HCV productively replicates in vitro in two closely related but functionally distinct types of T lymphocytes, CD4+ and CD8+ cells. The display of viral proteins and unique variants, the production of virions with biophysical properties distinct from those in plasma serving as inocula, and inhibition of replication by an antiviral agent led us to ascertain that both T cell subtypes supported virus propagation. Infection of CD4+ and CD8+ T cells, which are central to adaptive antiviral immune responses, can directly affect HCV clearance, favor virus persistence, and decisively influence the development and progression of hepatitis C.
Collapse
|
11
|
Beilstein F, Lemasson M, Pène V, Rainteau D, Demignot S, Rosenberg AR. Lysophosphatidylcholine acyltransferase 1 is downregulated by hepatitis C virus: impact on production of lipo-viro-particles. Gut 2017; 66:2160-2169. [PMID: 27582510 DOI: 10.1136/gutjnl-2016-311508] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 08/02/2016] [Accepted: 08/08/2016] [Indexed: 12/18/2022]
Abstract
OBJECTIVE HCV is intimately linked with the liver lipid metabolism, devoted to the efflux of triacylglycerols stored in lipid droplets (LDs) in the form of triacylglycerol-rich very-low-density lipoproteins (VLDLs): (i) the most infectious HCV particles are those of lowest density due to association with triacylglycerol-rich lipoproteins and (ii) HCV-infected patients frequently develop hepatic steatosis (increased triacylglycerol storage). The recent identification of lysophosphatidylcholine acyltransferase 1 (LPCAT1) as an LD phospholipid-remodelling enzyme prompted us to investigate its role in liver lipid metabolism and HCV infectious cycle. DESIGN Huh-7.5.1 cells and primary human hepatocytes (PHHs) were infected with JFH1-HCV. LPCAT1 depletion was achieved by RNA interference. Cells were monitored for LPCAT1 expression, lipid metabolism and HCV production and infectivity. The density of viral particles was assessed by isopycnic ultracentrifugation. RESULTS Upon HCV infection, both Huh-7.5.1 cells and PHH had decreased levels of LPCAT1 transcript and protein, consistent with transcriptional downregulation. LPCAT1 depletion in either naive or infected Huh-7.5.1 cells resulted in altered lipid metabolism characterised by LD remodelling, increased triacylglycerol storage and increased secretion of VLDL. In infected Huh-7.5.1 cells or PHH, LPCAT1 depletion increased production of the viral particles of lowest density and highest infectivity. CONCLUSIONS We have identified LPCAT1 as a modulator of liver lipid metabolism downregulated by HCV, which appears as a viral strategy to increase the triacylglycerol content and hence infectivity of viral particles. Targeting this metabolic pathway may represent an attractive therapeutic approach to reduce both the viral titre and hepatic steatosis.
Collapse
Affiliation(s)
- Frauke Beilstein
- Sorbonne Universités, UPMC Univ. Paris 06, Inserm, Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France.,EPHE, Ecole Pratique des Hautes Etudes, PSL Research University, Laboratoire de Pharmacologie Cellulaire et Moléculaire, Paris, France
| | - Matthieu Lemasson
- Université Paris Descartes, EA 4474 «Hepatitis C Virology», Paris, France
| | - Véronique Pène
- Université Paris Descartes, EA 4474 «Hepatitis C Virology», Paris, France
| | | | - Sylvie Demignot
- Sorbonne Universités, UPMC Univ. Paris 06, Inserm, Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France.,EPHE, Ecole Pratique des Hautes Etudes, PSL Research University, Laboratoire de Pharmacologie Cellulaire et Moléculaire, Paris, France
| | - Arielle R Rosenberg
- Université Paris Descartes, EA 4474 «Hepatitis C Virology», Paris, France.,AP-HP, Groupe Hospitalier Cochin, Service de Virologie, Paris, France
| |
Collapse
|
12
|
Guo X, Wang S, Qiu ZG, Dou YL, Liu WL, Yang D, Shen ZQ, Chen ZL, Wang JF, Zhang B, Wang XW, Guo XF, Zhang XL, Jin M, Li JW. Efficient replication of blood-borne hepatitis C virus in human fetal liver stem cells. Hepatology 2017; 66:1045-1057. [PMID: 28407288 DOI: 10.1002/hep.29211] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 04/05/2017] [Indexed: 02/06/2023]
Abstract
UNLABELLED The development of pathogenic mechanisms, specific antiviral treatments and preventive vaccines for hepatitis C virus (HCV) infection has been limited due to lack of cell culture models that can naturally imitate the entire HCV life cycle. Here, we established an HCV cell culture model based on human fetal liver stem cells (hFLSCs) that supports the entire blood-borne hepatitis C virus (bbHCV) life cycle. More than 90% of cells remained infected by various genotypes. bbHCV was efficiently propagated, and progeny virus were infectious to hFLSCs. The virus could be passed efficiently between cells. The viral infectivity was partially blocked by specific antibodies or small interfering RNA against HCV entry factors, whereas HCV replication was inhibited by antiviral drugs. We observed viral particles of approximately 55 nm in diameter in both cell culture media and infected cells after bbHCV infection. CONCLUSION Our data show that the entire bbHCV life cycle could be naturally imitated in hFLSCs. This model is expected to provide a powerful tool for exploring the process and the mechanism of bbHCV infection at the cellular level and for evaluating the treatment and preventive strategies of bbHCV infection. (Hepatology 2017;66:1045-1057).
Collapse
Affiliation(s)
- Xuan Guo
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Shu Wang
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Zhi-Gang Qiu
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Ya-Ling Dou
- Peking Union Medical College Hospital, Chinese Medical Academy, Beijing, China
| | - Wei-Li Liu
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Dong Yang
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Zhi-Qiang Shen
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Zhao-Li Chen
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Jing-Feng Wang
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Bin Zhang
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Xin-Wei Wang
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Xiang-Fei Guo
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Xue-Lian Zhang
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Min Jin
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| | - Jun-Wen Li
- Department of Environment and Health, Tianjin Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment & Food Safety, Tianjin, China
| |
Collapse
|
13
|
Hepatitis C Virus Lipoviroparticles Assemble in the Endoplasmic Reticulum (ER) and Bud off from the ER to the Golgi Compartment in COPII Vesicles. J Virol 2017; 91:JVI.00499-17. [PMID: 28515296 DOI: 10.1128/jvi.00499-17] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/12/2017] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) exists as a lipoprotein-virus hybrid lipoviroparticle (LVP). In vitro studies have demonstrated the importance of apolipoproteins in HCV secretion and infectivity, leading to the notion that HCV coopts the secretion of very-low-density lipoprotein (VLDL) for its egress. However, the mechanisms involved in virus particle assembly and egress are still elusive. The biogenesis of VLDL particles occurs in the endoplasmic reticulum (ER), followed by subsequent lipidation in the ER and Golgi compartment. The secretion of mature VLDL particles occurs through the Golgi secretory pathway. HCV virions are believed to latch onto or fuse with the nascent VLDL particle in either the ER or the Golgi compartment, resulting in the generation of LVPs. In our attempt to unravel the collaboration between HCV and VLDL secretion, we studied HCV particles budding from the ER en route to the Golgi compartment in COPII vesicles. Biophysical characterization of COPII vesicles fractionated on an iodixanol gradient revealed that HCV RNA is enriched in the highly buoyant COPII vesicle fractions and cofractionates with apolipoprotein B (ApoB), ApoE, and the HCV core and envelope proteins. Electron microscopy of immunogold-labeled microsections revealed that the HCV envelope and core proteins colocalize with apolipoproteins and HCV RNA in Sec31-coated COPII vesicles. Ultrastructural analysis also revealed the presence of HCV structural proteins, RNA, and apolipoproteins in the Golgi stacks. These findings support the hypothesis that HCV LVPs assemble in the ER and are transported to the Golgi compartment in COPII vesicles to embark on the Golgi secretory route.IMPORTANCE HCV assembly and release accompany the formation of LVPs that circulate in the sera of HCV patients and are also produced in an in vitro culture system. The pathway of HCV morphogenesis and secretion has not been fully understood. This study investigates the exact site where the association of HCV virions with host lipoproteins occurs. Using immunoprecipitation of COPII vesicles and immunogold electron microscopy (EM), we characterize the existence of LVPs that cofractionate with lipoproteins, viral proteins, RNA, and vesicular components. Our results show that this assembly occurs in the ER, and LVPs thus formed are carried through the Golgi network by vesicular transport. This work provides a unique insight into the HCV LVP assembly process within infected cells and offers opportunities for designing antiviral therapeutic cellular targets.
Collapse
|
14
|
Pène V, Lemasson M, Harper F, Pierron G, Rosenberg AR. Role of cleavage at the core-E1 junction of hepatitis C virus polyprotein in viral morphogenesis. PLoS One 2017; 12:e0175810. [PMID: 28437468 PMCID: PMC5402940 DOI: 10.1371/journal.pone.0175810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 03/31/2017] [Indexed: 12/17/2022] Open
Abstract
In hepatitis C virus (HCV) polyprotein sequence, core protein terminates with E1 envelope signal peptide. Cleavage by signal peptidase (SP) separates E1 from the complete form of core protein, anchored in the endoplasmic reticulum (ER) membrane by the signal peptide. Subsequent cleavage of the signal peptide by signal-peptide peptidase (SPP) releases the mature form of core protein, which preferentially relocates to lipid droplets. Both of these cleavages are required for the HCV infectious cycle, supporting the idea that HCV assembly begins at the surface of lipid droplets, yet SPP-catalyzed cleavage is dispensable for initiation of budding in the ER. Here we have addressed at what step(s) of the HCV infectious cycle SP-catalyzed cleavage at the core-E1 junction is required. Taking advantage of the sole system that has allowed visualization of HCV budding events in the ER lumen of mammalian cells, we showed that, unexpectedly, mutations abolishing this cleavage did not prevent but instead tended to promote the initiation of viral budding. Moreover, even though no viral particles were released from Huh-7 cells transfected with a full-length HCV genome bearing these mutations, intracellular viral particles containing core protein protected by a membrane envelope were formed. These were visualized by electron microscopy as capsid-containing particles with a diameter of about 70 nm and 40 nm before and after delipidation, respectively, comparable to intracellular wild-type particle precursors except that they were non-infectious. Thus, our results show that SP-catalyzed cleavage is dispensable for HCV budding per se, but is required for the viral particles to acquire their infectivity and secretion. These data support the idea that HCV assembly occurs in concert with budding at the ER membrane. Furthermore, capsid-containing particles did not accumulate in the absence of SP-catalyzed cleavage, suggesting the quality of newly formed viral particles is controlled before secretion.
Collapse
Affiliation(s)
- Véronique Pène
- Université Paris Descartes, EA 4474 “Virologie de l’Hépatite C”, Paris, France
| | - Matthieu Lemasson
- Université Paris Descartes, EA 4474 “Virologie de l’Hépatite C”, Paris, France
| | - Francis Harper
- CNRS UMR 9196, Institut Gustave Roussy, Villejuif, France
| | - Gérard Pierron
- CNRS UMR 9196, Institut Gustave Roussy, Villejuif, France
| | - Arielle R. Rosenberg
- Université Paris Descartes, EA 4474 “Virologie de l’Hépatite C”, Paris, France
- AP-HP, Hôpital Cochin, Service de Virologie, Paris, France
| |
Collapse
|
15
|
Falcón V, Acosta-Rivero N, González S, Dueñas-Carrera S, Martinez-Donato G, Menéndez I, Garateix R, Silva JA, Acosta E, Kourı J. Ultrastructural and biochemical basis for hepatitis C virus morphogenesis. Virus Genes 2017; 53:151-164. [PMID: 28233195 DOI: 10.1007/s11262-017-1426-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 01/06/2017] [Indexed: 12/16/2022]
Abstract
Chronic infection with HCV is a leading cause of cirrhosis, hepatocellular carcinoma and liver failure. One of the least understood steps in the HCV life cycle is the morphogenesis of new viral particles. HCV infection alters the lipid metabolism and generates a variety of microenvironments in the cell cytoplasm that protect viral proteins and RNA promoting viral replication and assembly. Lipid droplets (LDs) have been proposed to link viral RNA synthesis and virion assembly by physically associating these viral processes. HCV assembly, envelopment, and maturation have been shown to take place at specialized detergent-resistant membranes in the ER, rich in cholesterol and sphingolipids, supporting the synthesis of luminal LDs-containing ApoE. HCV assembly involves a regulated allocation of viral and host factors to viral assembly sites. Then, virus budding takes place through encapsidation of the HCV genome and viral envelopment in the ER. Interaction of ApoE with envelope proteins supports the viral particle acquisition of lipids and maturation. HCV secretion has been suggested to entail the ion channel activity of viral p7, several components of the classical trafficking and autophagy pathways, ESCRT, and exosome-mediated export of viral RNA. Here, we review the most recent advances in virus morphogenesis and the interplay between viral and host factors required for the formation of HCV virions.
Collapse
Affiliation(s)
- Viviana Falcón
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba.
| | - Nelson Acosta-Rivero
- National Center for Scientific Research, P.O. Box 6414, 10600, Havana, Cuba. .,Centre for Protein Studies, Faculty of Biology, University of Havana, 10400, Havana, Cuba.
| | | | | | | | - Ivon Menéndez
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba
| | - Rocio Garateix
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba
| | - José A Silva
- Centro de Ingeniería Genética y Biotecnología, P.O. Box 6162, C.P. 10600, Havana, Cuba
| | | | | |
Collapse
|
16
|
Sheridan DA, Hajarizadeh B, Fenwick FI, Matthews GV, Applegate T, Douglas M, Neely D, Askew B, Dore GJ, Lloyd AR, George J, Bassendine MF, Grebely J. Maximum levels of hepatitis C virus lipoviral particles are associated with early and persistent infection. Liver Int 2016; 36:1774-1782. [PMID: 27224844 DOI: 10.1111/liv.13176] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/21/2016] [Indexed: 02/13/2023]
Abstract
BACKGROUND & AIMS Hepatitis C virus (HCV) is bound to plasma lipoproteins and circulates as an infectious lipoviral particle (LVP). Experimental evidence indicates that LVPs have decreased susceptibility to antibody-mediated neutralisation and higher infectivity. This study tested the hypothesis that LVPs are required to establish persistent infection, and conversely, low levels of LVP in recent HCV infection increase the probability of spontaneous HCV clearance. METHODS LVP in non-fasting plasma was measured using the concentration of HCV RNA bound to large >100 nm sized lipoproteins after ex vivo addition of a lipid emulsion, that represented the maximum concentration of LVP (maxi-LVP). This method correlated with LVP in fasting plasma measured using iodixanol density gradient ultracentrifugation. Maxi-LVP was measured in a cohort of 180 HCV participants with recent HCV infection and detectable HCV RNA from the Australian Trial in Acute Hepatitis C (ATAHC) and Hepatitis C Incidence and Transmission Study in prison (HITS-p) cohorts. RESULTS Spontaneous clearance occurred in 15% (27 of 180) of individuals. In adjusted analyses, low plasma maxi-LVP level was independently associated with spontaneous HCV clearance (≤827 IU/ml; adjusted odds ratio 3.98, 95% CI: 1.02, 15.51, P = 0.047), after adjusting for interferon lambda-3 rs8099917 genotype, estimated duration of HCV infection and total HCV RNA level. CONCLUSIONS Maxi-LVP is a biomarker for the maximum concentration of LVP in non-fasting samples. Low maxi-LVP level is an independent predictor of spontaneous clearance of acute HCV.
Collapse
Affiliation(s)
- David A Sheridan
- Storr Liver Centre, Westmead Millennium Institute and Westmead Hospital, University of Sydney, Sydney, NSW, Australia
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
- Institute of Translational and Stratified Medicine, Plymouth University Peninsula Schools of Medicine & Dentistry, Plymouth, UK
| | | | - Fiona I Fenwick
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
| | - Gail V Matthews
- The Kirby Institute, UNSW Australia, Kensington, NSW, Australia
| | - Tanya Applegate
- The Kirby Institute, UNSW Australia, Kensington, NSW, Australia
| | - Mark Douglas
- Storr Liver Centre, Westmead Millennium Institute and Westmead Hospital, University of Sydney, Sydney, NSW, Australia
| | - Dermot Neely
- Department of Clinical Biochemistry, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Bev Askew
- HB Innovations Ltd, Newcastle upon Tyne, UK
| | - Gregory J Dore
- The Kirby Institute, UNSW Australia, Kensington, NSW, Australia
| | - Andrew R Lloyd
- Inflammation and Infection Research Centre, School of Medical Sciences, The University of New South Wales, Kensington, NSW, Australia
| | - Jacob George
- Storr Liver Centre, Westmead Millennium Institute and Westmead Hospital, University of Sydney, Sydney, NSW, Australia
| | - Margaret F Bassendine
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK
- Department of Medicine, Imperial College London, London, UK
| | - Jason Grebely
- The Kirby Institute, UNSW Australia, Kensington, NSW, Australia
| |
Collapse
|
17
|
Neglected but Important Role of Apolipoprotein E Exchange in Hepatitis C Virus Infection. J Virol 2016; 90:9632-9643. [PMID: 27535051 DOI: 10.1128/jvi.01353-16] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/03/2016] [Indexed: 12/22/2022] Open
Abstract
Hepatitis C virus (HCV) is a major cause of chronic liver disease, infecting approximately 170 million people worldwide. HCV assembly is tightly associated with the lipoprotein pathway. Exchangeable apolipoprotein E (apoE) is incorporated on infectious HCV virions and is important for infectious HCV virion morphogenesis and entry. Moreover, the virion apoE level is positively correlated with its ability to escape E2 antibody neutralization. However, the role of apoE exchange in the HCV life cycle is unclear. In this study, the relationship between apoE expression and cell permissiveness to HCV infection was assessed by infecting apoE knockdown and derived apoE rescue cell lines with HCV. Exchange of apoE between lipoproteins and HCV lipoviral particles (LVPs) was evaluated by immunoprecipitation, infectivity testing, and viral genome quantification. Cell and heparin column binding assays were applied to determine the attachment efficiency of LVPs with different levels of incorporated apoE. The results showed that cell permissiveness for HCV infection was determined by exogenous apoE-associated lipoproteins. Furthermore, apoE exchange did occur between HCV LVPs and lipoproteins, which was important to maintain a high apoE level on LVPs. Lipid-free apoE was capable of enhancing HCV infectivity for apoE knockdown cells but not apoE rescue cells. A higher apoE level on LVPs conferred more efficient LVP attachment to both the cell surface and heparin beads. This study revealed that exogenous apoE-incorporating lipoproteins from uninfected hepatocytes safeguarded the apoE level of LVPs for more efficient attachment during HCV infection. IMPORTANCE In this study, a neglected but important role of apoE exchange in HCV LVP infectivity after virus assembly and release was identified. The data indicated that apoE expression level in uninfected cells is important for high permissiveness to HCV infection. Secreted apoE-associated lipoprotein specifically enhances infection of HCV LVPs. apoE exchange between HCV LVP and lipoproteins is important to maintain an adequate apoE level on LVPs for their efficient attachment to cell surface. These data defined for the first time an extracellular role of exchangeable apoE in HCV infection and suggested that exchangeable apolipoproteins reach a natural equilibrium between HCV LVPs and lipoprotein particles, which provides a new perspective to the understanding of the heterogeneity of HCV LVPs in composition.
Collapse
|
18
|
Roles of human apolipoprotein E in the infectivity and replication of hepatitis C virus genotype 2a. J Microbiol 2016; 54:451-8. [PMID: 27225463 DOI: 10.1007/s12275-016-6099-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 04/18/2016] [Accepted: 04/20/2016] [Indexed: 02/08/2023]
Abstract
Hepatitis C virus (HCV) infection is associated with lipoproteins, and apolipoprotein E (apoE) plays an essential role in infectious HCV particles. Although the role of apoE in HCV infection is well known, its role in the replication of HCV remains unclear. The aims of this study were to determine the role of apoE in the RNA replication of major HCV genotypes 1b and 2a, and to determine whether this role is HCVgenotype-dependent using HCV genotype 1b replicon cells and HCV genotype 2a producing (HP) cells. HCV infection was blocked in Huh7.5 cells treated with low-density lipoproteins, very low-density lipoproteins, or apoE3. An apoE3-specific monoclonal antibody also efficiently neutralized HCV infectivity, and HCV infection was dramatically suppressed by the knockdown of apoE expression with an apoE-specific small interfering RNA, suggesting a requirement for apoE in infectious HCV particles. HCV RNA replication was not affected in HP cells treated with each apoE isoform or transfected with apoE-specific siRNAs. However, the knockdown of apoE expression suppressed RNA replication of HCV genotype 1b. The siRNA-mediated knockdown of apoE, apoA1, and apoB expression also suppressed the RNA replication of HCV genotype 1b, but not that of HCV genotype 2a. Taken together, these findings indicate that apoE plays an important role in HCV genotype 2a infection and in HCV genotype 1b RNA replication, but not in the replication of HCV genotype 2a. These results provide important information for the future development of HCV-genotypespecific anti-HCV agents.
Collapse
|
19
|
Grassi G, Di Caprio G, Fimia GM, Ippolito G, Tripodi M, Alonzi T. Hepatitis C virus relies on lipoproteins for its life cycle. World J Gastroenterol 2016; 22:1953-1965. [PMID: 26877603 PMCID: PMC4726671 DOI: 10.3748/wjg.v22.i6.1953] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/19/2015] [Accepted: 12/21/2015] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) infects over 150 million people worldwide. In most cases, HCV infection becomes chronic causing liver disease ranging from fibrosis to cirrhosis and hepatocellular carcinoma. Viral persistence and pathogenesis are due to the ability of HCV to deregulate specific host processes, mainly lipid metabolism and innate immunity. In particular, HCV exploits the lipoprotein machineries for almost all steps of its life cycle. The aim of this review is to summarize current knowledge concerning the interplay between HCV and lipoprotein metabolism. We discuss the role played by members of lipoproteins in HCV entry, replication and virion production.
Collapse
|
20
|
Stefas I, Tigrett S, Dubois G, Kaiser M, Lucarz E, Gobby D, Bray D, Ellerbrok H, Zarski JP, Veas F. Interactions between Hepatitis C Virus and the Human Apolipoprotein H Acute Phase Protein: A Tool for a Sensitive Detection of the Virus. PLoS One 2015; 10:e0140900. [PMID: 26502286 PMCID: PMC4621047 DOI: 10.1371/journal.pone.0140900] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 10/01/2015] [Indexed: 12/20/2022] Open
Abstract
The Hepatitis C virus (HCV) infection exhibits a high global prevalence frequently associated with hepatocellular carcinoma, taking years to develop. Despite the standardization of highly sensitive HCV quantitative RT-PCR (qRT-PCR) detection methods, false-negative diagnoses may be generated with current methods, mainly due to the presence of PCR inhibitors and/or low viral loads in the patient’s sample. These false-negative diagnoses impact both public health systems, in developing countries, and an in lesser extent, in developed countries, including both the risk of virus transmission during organ transplantation and/or blood transfusion and the quality of the antiviral treatment monitoring. To adopt an appropriate therapeutic strategy to improve the patient’s prognosis, it is urgent to increase the HCV detection sensitivity. Based upon previous studies on HBV, we worked on the capacity of the scavenger acute phase protein, Apolipoprotein H (ApoH) to interact with HCV. Using different approaches, including immunoassays, antibody-inhibition, oxidation, ultracentrifugation, electron microscopy and RT-PCR analyses, we demonstrated specific interactions between HCV particles and ApoH. Moreover, when using a two-step HCV detection process, including capture of HCV by ApoH-coated nanomagnetic beads and a home-made real-time HCV-RT-PCR, we confirmed the presence of HCV for all samples from a clinical collection of HCV-seropositive patients exhibiting an RT-PCR COBAS® TaqMan® HCV Test, v2.0 (COBAS)-positive result. In contrast, for HCV-seropositive patients with either low HCV-load as determined with COBAS or exhibiting HCV-negative COBAS results, the addition of the two-step ApoH-HCV-capture and HCV-detection process was able to increase the sensitivity of HCV detection or more interestingly, detect in a genotype sequence-independent manner, a high-proportion (44%) of HCV/RNA-positive among the COBAS HCV-negative patients. Thus, the immune interaction between ApoH and HCV could be used as a sample preparation tool to enrich and/or cleanse HCV patient’s samples to enhance the detection sensitivity of HCV and therefore significantly reduce the numbers of false-negative HCV diagnosis results.
Collapse
Affiliation(s)
- Ilias Stefas
- ApoH-Technologies, Faculté de Pharmacie, Université de Montpellier, Montpellier, France
| | - Sylvia Tigrett
- ApoH-Technologies, Faculté de Pharmacie, Université de Montpellier, Montpellier, France; Institut de Recherche pour le Développement, UMR-Ministère de la Défense 3, Laboratoire d'Immuno-Physiopathologie Moléculaire Comparée, Faculté de Pharmacie, Montpellier, France
| | - Grégor Dubois
- Institut de Recherche pour le Développement, UMR-Ministère de la Défense 3, Laboratoire d'Immuno-Physiopathologie Moléculaire Comparée, Faculté de Pharmacie, Montpellier, France
| | | | - Estelle Lucarz
- ApoH-Technologies, Faculté de Pharmacie, Université de Montpellier, Montpellier, France
| | - Delphine Gobby
- ApoH-Technologies, Faculté de Pharmacie, Université de Montpellier, Montpellier, France
| | - Dorothy Bray
- Immunoclin Corporation, Washington, DC, United States of America
| | - Heinz Ellerbrok
- Robert Koch-Institute, Centre for Biological Threats and Special Pathogens, Highly Pathogenic Viruses, Berlin, Germany
| | - Jean Pierre Zarski
- Clinique d'Hépato-gastroentérologie, Centre Hospitalier Universitaire de Grenoble, IAB, INSERM U823, Grenoble, France
| | - Francisco Veas
- Institut de Recherche pour le Développement, UMR-Ministère de la Défense 3, Laboratoire d'Immuno-Physiopathologie Moléculaire Comparée, Faculté de Pharmacie, Montpellier, France
| |
Collapse
|
21
|
Apolipoprotein E, but Not Apolipoprotein B, Is Essential for Efficient Cell-to-Cell Transmission of Hepatitis C Virus. J Virol 2015. [PMID: 26202245 DOI: 10.1128/jvi.00577-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) infects hepatocytes through two different routes: (i) cell-free particle diffusion followed by engagement with specific cellular receptors and (ii) cell-to-cell direct transmission mediated by mechanisms not well defined yet. HCV exits host cells in association with very-low-density lipoprotein (VLDL) components. VLDL particles contain apolipoproteins B (ApoB) and E (ApoE), which are required for viral assembly and/or infectivity. Based on these precedents, we decided to study whether these VLDL components participate in HCV cell-to-cell transmission in vitro. We observed that cell-to-cell viral spread was compromised after ApoE interference in donor but not in acceptor cells. In contrast, ApoB knockdown in either donor or acceptor cells did not impair cell-to-cell viral transmission. Interestingly, ApoB participated in the assembly of cell-free infective virions, suggesting a differential regulation of cell-to-cell and cell-free HCV infection. This study identifies host-specific factors involved in these distinct routes of infection that may unveil new therapeutic targets and advance our understanding of HCV pathogenesis. IMPORTANCE This work demonstrates that cell-to-cell transmission of HCV depends on ApoE but not ApoB. The data also indicate that ApoB is required for the assembly of cell-free infective particles, strongly suggesting the existence of mechanisms involving VLDL components that differentially regulate cell-free and cell-to-cell HCV transmission. These data clarify some of the questions regarding the role of VLDL in HCV pathogenesis and the transmission of the virus cell to cell as a possible mechanism of immune evasion and open the door to therapeutic intervention.
Collapse
|
22
|
The Serum Very-Low-Density Lipoprotein Serves as a Restriction Factor against Hepatitis C Virus Infection. J Virol 2015; 89:6782-91. [PMID: 25903344 DOI: 10.1128/jvi.00194-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/10/2015] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Recent studies demonstrated that transgenic mice expressing key human hepatitis C virus (HCV) receptors are susceptible to HCV infection, albeit at very low efficiency. Robust mouse models of HCV infection and replication are needed to determine the importance of host factors in HCV replication, pathogenesis, and carcinogenesis as well as to facilitate the development of antiviral agents and vaccines. The low efficiency of HCV replication in the humanized mouse models is likely due to either the lack of essential host factors or the presence of restriction factors for HCV infection and/or replication in mouse hepatocytes. To determine whether HCV infection is affected by restriction factors present in serum, we examined the effects of mouse and human sera on HCV infectivity. Strikingly, we found that mouse and human sera potently inhibited HCV infection. Mechanistic studies demonstrated that mouse serum blocked HCV cell attachment without significant effect on HCV replication. Fractionation analysis of mouse serum in conjunction with targeted mass spectrometric analysis suggested that serum very-low-density lipoprotein (VLDL) was responsible for the blockade of HCV cell attachment, as VLDL-depleted mouse serum lost HCV-inhibitory activity. Both purified mouse and human VLDL could efficiently inhibit HCV infection. Collectively, these findings suggest that serum VLDL serves as a major restriction factor of HCV infection in vivo. The results also imply that reduction or elimination of VLDL production will likely enhance HCV infection in the humanized mouse model of HCV infection and replication. IMPORTANCE HCV is a major cause of liver diseases, such as chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Recently, several studies suggested that humanized mouse or transgenic mouse expressing key HCV human receptors became susceptible to HCV infection. However, HCV infection and replication in the humanized animals were very inefficient, suggesting either the lack of cellular genes important for HCV replication or the presence of restriction factors inhibiting HCV infection and replication in the mouse. In this study, we found that both mouse and human sera effectively inhibited HCV infection. Mechanistic studies demonstrated that VLDL is the major restriction factor that blocks HCV infection. These findings suggest that VLDL is beneficial to patients by restricting HCV infection. More importantly, our findings suggest that elimination of VLDL will lead to the development of more robust mouse models for the study of HCV pathogenesis, host response to HCV infection, and evaluation of HCV vaccines.
Collapse
|
23
|
Abstract
UNLABELLED Although it is well established that hepatitis C virus (HCV) entry into hepatocytes depends on clathrin-mediated endocytosis, the possible roles of clathrin in other steps of the viral cycle remain unexplored. Thus, we studied whether cell culture-derived HCV (HCVcc) exocytosis was altered after clathrin interference. Knockdown of clathrin or the clathrin adaptor AP-1 in HCVcc-infected human hepatoma cell cultures impaired viral secretion without altering intracellular HCVcc levels or apolipoprotein B (apoB) and apoE exocytosis. Similar reductions in HCVcc secretion were observed after treatment with specific clathrin and dynamin inhibitors. Furthermore, detergent-free immunoprecipitation assays, neutralization experiments, and immunofluorescence analyses suggested that whereas apoE associated with infectious intracellular HCV precursors in endoplasmic reticulum (ER)-related structures, AP-1 participated in HCVcc egress in a post-ER compartment. Finally, we observed that clathrin and AP-1 knockdown altered the endosomal distribution of HCV core, reducing and increasing its colocalization with early endosome and lysosome markers, respectively. Our data support a model in which nascent HCV particles associate with apoE in the ER and exit cells following a clathrin-dependent transendosomal secretory route. IMPORTANCE HCV entry into hepatocytes depends on clathrin-mediated endocytosis. Here we demonstrate for the first time that clathrin also participates in HCV exit from infected cells. Our data uncover important features of HCV egress, which may lead to the development of new therapeutic interventions. Interestingly, we show that secretion of the very-low-density lipoprotein (VLDL) components apoB and apoE is not impaired after clathrin interference. This is a significant finding, since, to date, it has been proposed that HCV and VLDL follow similar exocytic routes. Given that lipid metabolism recently emerged as a potential target for therapies against HCV infection, our data may help in the design of new strategies to interfere specifically with HCV exocytosis without perturbing cellular lipid homeostasis, with the aim of achieving more efficient, selective, and safe antivirals.
Collapse
|
24
|
Liefhebber JMP, Hague CV, Zhang Q, Wakelam MJO, McLauchlan J. Modulation of triglyceride and cholesterol ester synthesis impairs assembly of infectious hepatitis C virus. J Biol Chem 2014; 289:21276-88. [PMID: 24917668 PMCID: PMC4118089 DOI: 10.1074/jbc.m114.582999] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In hepatitis C virus infection, replication of the viral genome and virion assembly are linked to cellular metabolic processes. In particular, lipid droplets, which store principally triacylglycerides (TAGs) and cholesterol esters (CEs), have been implicated in production of infectious virus. Here, we examine the effect on productive infection of triacsin C and YIC-C8-434, which inhibit synthesis of TAGs and CEs by targeting long-chain acyl-CoA synthetase and acyl-CoA:cholesterol acyltransferase, respectively. Our results present high resolution data on the acylglycerol and cholesterol ester species that were affected by the compounds. Moreover, triacsin C, which blocks both triglyceride and cholesterol ester synthesis, cleared most of the lipid droplets in cells. By contrast, YIC-C8-434, which only abrogates production of cholesterol esters, induced an increase in size of droplets. Although both compounds slightly reduced viral RNA synthesis, they significantly impaired assembly of infectious virions in infected cells. In the case of triacsin C, reduced stability of the viral core protein, which forms the virion nucleocapsid and is targeted to the surface of lipid droplets, correlated with lower virion assembly. In addition, the virus particles that were released from cells had reduced specific infectivity. YIC-C8-434 did not alter the association of core with lipid droplets but appeared to decrease production of infectious virus particles, suggesting a block in virion assembly. Thus, the compounds have antiviral properties, indicating that targeting synthesis of lipids stored in lipid droplets might be an option for therapeutic intervention in treating chronic hepatitis C virus infection.
Collapse
Affiliation(s)
- Jolanda M P Liefhebber
- From the Medical Research Council-University of Glasgow Centre for Virus Research, 8 Church Street, Glasgow G11 5JR, Scotland, United Kingdom and
| | - Charlotte V Hague
- From the Medical Research Council-University of Glasgow Centre for Virus Research, 8 Church Street, Glasgow G11 5JR, Scotland, United Kingdom and
| | - Qifeng Zhang
- The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Michael J O Wakelam
- The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - John McLauchlan
- From the Medical Research Council-University of Glasgow Centre for Virus Research, 8 Church Street, Glasgow G11 5JR, Scotland, United Kingdom and
| |
Collapse
|
25
|
Abstract
The lifecycle of several viruses is intimately tied to the lipid metabolism of their host cells, and lipid droplets (LDs) have emerged as crucial organelles in the propagation of these viral infections. Investigating the roles of LDs in viral infection requires expertise in both virology and cell metabolism pertaining to LDs. In this review, we offer an updated list and review of the multiples methods we have used in our laboratory to study both the role of LDs in viral infection and the effect of viral infection on cellular LDs, with a special emphasis on hepatitis C virus and other RNA viruses.
Collapse
|
26
|
The role of chemokines in acute and chronic hepatitis C infection. Cell Mol Immunol 2013; 11:25-40. [PMID: 23954947 DOI: 10.1038/cmi.2013.37] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Revised: 07/08/2013] [Accepted: 07/14/2013] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C imposes a significant burden on global healthcare. Chronic infection is associated with progressive inflammation of the liver which typically manifests in cirrhosis, organ failure and cancer. By virtue of elaborate evasion strategies, hepatitis C virus (HCV) succeeds as a persistent human virus. It has an extraordinary capacity to subvert the immune response enabling it to establish chronic infections and associated liver disease. Chemokines are low molecular weight chemotactic peptides that mediate the recruitment of inflammatory cells into tissues and back into the lymphatics and peripheral blood. Thus, they are central to the temporal and spatial distribution of effector and regulatory immune cells. The interactions between chemokines and their cognate receptors help shape the immune response and therefore, have a major influence on the outcome of infection. However, chemokines represent a target for modulation by viruses including the HCV. HCV is known to modulate chemokine expression in vitro and may therefore enable its survival by subverting the immune response in vivo through altered leukocyte chemotaxis resulting in impaired viral clearance and the establishment of chronic low-grade inflammation. In this review, the roles of chemokines in acute and chronic HCV infection are described with a particular emphasis placed on chemokine modulation as a means of immune subversion. We provide an in depth discussion of the part played by chemokines in mediating hepatic fibrosis while addressing the potential applications for these chemoattractants in prognostic medicine.
Collapse
|
27
|
Hepatitis C virus, cholesterol and lipoproteins--impact for the viral life cycle and pathogenesis of liver disease. Viruses 2013; 5:1292-324. [PMID: 23698400 PMCID: PMC3712309 DOI: 10.3390/v5051292] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/10/2013] [Accepted: 04/27/2013] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C virus (HCV) is a leading cause of chronic liver disease, including chronic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Hepatitis C infection associates with lipid and lipoprotein metabolism disorders such as hepatic steatosis, hypobetalipoproteinemia, and hypocholesterolemia. Furthermore, virus production is dependent on hepatic very-low-density lipoprotein (VLDL) assembly, and circulating virions are physically associated with lipoproteins in complexes termed lipoviral particles. Evidence has indicated several functional roles for the formation of these complexes, including co-opting of lipoprotein receptors for attachment and entry, concealing epitopes to facilitate immune escape, and hijacking host factors for HCV maturation and secretion. Here, we review the evidence surrounding pathogenesis of the hepatitis C infection regarding lipoprotein engagement, cholesterol and triglyceride regulation, and the molecular mechanisms underlying these effects.
Collapse
|
28
|
|
29
|
Perrin-Cocon L, Diaz O, André P, Lotteau V. Modified lipoproteins provide lipids that modulate dendritic cell immune function. Biochimie 2012; 95:103-8. [PMID: 22959067 DOI: 10.1016/j.biochi.2012.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 08/09/2012] [Indexed: 12/19/2022]
Abstract
Both physiological and pathological situations can result in biochemical changes of low-density lipoproteins (LDL). Because they can deliver signals to dendritic cells (DC), these modified lipoproteins now appear as regulators of the immune response. Among these modified lipoproteins, oxidized LDL (oxLDL) that accumulate during inflammatory conditions have been extensively studied. Numerous studies have shown that oxLDL induce the maturation of DC, enhancing their ability to activate IFNγ secretion by T cells. LDL treated by secreted phospholipase A(2) also promote DC maturation. Among the bioactive lipids generated by oxidation or phospholipase treatment of LDL, lysophosphatidylcholine (LPC) and some saturated fatty acids induce DC maturation whereas some unsaturated fatty acids or oxidized derivatives have opposite effects. Among other factors, the nuclear receptor peroxisome-proliferator activated receptor γ (PPARγ) plays a crucial role in this regulation. Non-modified lipoproteins also contribute to the regulation of DC function, suggesting that the balance between native and modified lipoproteins, as well as the biochemical nature of the LDL modifications, can regulate the activation threshold of DC. Here we discuss two pathological situations in which the impact of LDL modifications on inflammation and immunity could play an important role. During atherosclerosis, modified LDL accumulating in the arterial intima may interfere with DC maturation and function, promoting a Th1 immune response and a local inflammation favoring the development of the pathology. In patients chronically infected, the hepatitis C virus (HCV) interferes with lipoprotein metabolism resulting in the production of infectious modified lipoproteins. These lipo-viral-particles (LVP) are modified low-density lipoproteins containing viral material that can alter DC maturation and affect specific toll-like receptor signaling. In conclusion, lipoprotein modifications play an important role in the regulation of immunity by delivering signals of danger to DC and modulating their function.
Collapse
|
30
|
Scholtes C, Ramière C, Rainteau D, Perrin-Cocon L, Wolf C, Humbert L, Carreras M, Guironnet-Paquet A, Zoulim F, Bartenschlager R, Lotteau V, André P, Diaz O. High plasma level of nucleocapsid-free envelope glycoprotein-positive lipoproteins in hepatitis C patients. Hepatology 2012; 56:39-48. [PMID: 22290760 DOI: 10.1002/hep.25628] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Accepted: 01/19/2012] [Indexed: 02/06/2023]
Abstract
UNLABELLED Hepatitis C virus (HCV) particles associate viral and lipoprotein moieties to form hybrid lipoviral particles (LVPs). Cell culture-produced HCV (HCVcc) and ex vivo-characterized LVPs primarily differ by their apolipoprotein (apo) B content, which is low for HCVcc, but high for LVPs. Recombinant nucleocapsid-free subviral LVPs are assembled and secreted by apoB-producing cell lines. To determine whether such subviral particles circulate in HCV-infected individuals, LVPs complexed with immunoglobulin were precipitated with protein A from low-density plasma fractions of 36 hepatitis C patients, and their lipid content, apolipoprotein profile, and viral composition were determined. HCV RNA in LVPs was quantified and molar ratios of apoB and HCV genome copy number were calculated. LVPs lipidome from four patients was determined via electrospray ionization/tandem mass spectrometry. Protein A-purified LVPs contained at least the envelope glycoprotein E2 and E2-specific antibodies. LVPs were present in every patient and were characterized by high lipid content, presence of apolipoproteins characteristic of triglyceride-rich lipoproteins (TRLs), HCV RNA, and viral glycoprotein. Importantly, save for four patients, LVPs fractions contained large amounts of apoB, with on average more than 1 × 10(6) apoB molecules per HCV RNA genome. Because there is one apoB molecule per TRL, this ratio suggested that most LVPs are nucleocapsid-free, envelope glycoprotein-containing subviral particles. LVPs and TRLs had similar composition of triacylglycerol and phospholipid classes. CONCLUSION LVPs are a mixed population of particles, comprising predominantly subviral particles that represent a distinct class of modified lipoproteins within the TRL family.
Collapse
|
31
|
Abstract
Cholesterol is an essential molecule for the life cycle of the hepatitis C virus (HCV). This review focuses on the roles of cholesterol in HCV infection and introduces HCV events related to cholesterol metabolism and applications for cholesterol metabolism as a therapeutic target. HCV appears to alter host lipid metabolism into its preferable state, which is clinically recognized as steatosis and hypocholesterolemia. While hepatic fatty acid and triglyceride syntheses are upregulated in chronic hepatitis C patients, no direct evidence of increased hepatic de novo cholesterol biosynthesis has been obtained. Impaired VLDL secretion from hepatocytes is suggested to increase intracellular cholesterol concentrations, which may lead to hypocholesterolemia. Clinically, lower serum cholesterol levels are associated with lower rates of sustained virological responses (SVR) to pegylated-interferon plus ribavirin therapy, but the reason remains unclear. Clinical trials targeting HMG-CoA reductase, the rate-limiting enzyme in the cholesterol biosynthetic pathway, are being conducted using statins. Anti-HCV actions by statins appear to be caused by the inhibition of geranylgeranyl pyrophosphate synthesis rather than their cholesterol lowering effects. Other compounds that block various steps of cholesterol metabolic pathways have also been studied to develop new strategies for the complete eradication of this virus.
Collapse
Affiliation(s)
- Akira Honda
- Department of Gastroenterology, Tokyo Medical University Ibaraki Medical Center, Ibaraki, Japan
| | | |
Collapse
|
32
|
Herker E, Ott M. Unique ties between hepatitis C virus replication and intracellular lipids. Trends Endocrinol Metab 2011; 22:241-8. [PMID: 21497514 PMCID: PMC3118981 DOI: 10.1016/j.tem.2011.03.004] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Revised: 03/09/2011] [Accepted: 03/15/2011] [Indexed: 12/11/2022]
Abstract
Hepatitis C virus (HCV) infects approximately 3% of the world's population, establishing a lifelong infection in the majority of cases. The life cycle of HCV is closely tied to the lipid metabolism of liver cells, and lipid droplets have emerged as crucial intracellular organelles that support persistent propagation of viral infection. In this review, we examine recent advances in our understanding of how HCV usurps intracellular lipids to propagate, and highlight unique opportunities for therapeutic intervention.
Collapse
Affiliation(s)
- Eva Herker
- Gladstone Institute of Virology and Immunology; 1650 Owens Street, San Francisco, California 94158
- Department of Medicine, University of California, San Francisco, CA 94143, USA
- Liver Center, University of California, San Francisco, CA 94143, USA
| | - Melanie Ott
- Gladstone Institute of Virology and Immunology; 1650 Owens Street, San Francisco, California 94158
- Department of Medicine, University of California, San Francisco, CA 94143, USA
- Liver Center, University of California, San Francisco, CA 94143, USA
- To whom correspondence should be addressed: Melanie Ott, MD, PhD, Gladstone Institute of Virology and Immunology, 1650 Owens Street, San Francisco, CA 94158, Tel: (415) 734-4807, Fax: (415) 355-0855,
| |
Collapse
|
33
|
Akazawa D, Morikawa K, Omi N, Takahashi H, Nakamura N, Mochizuki H, Date T, Ishii K, Suzuki T, Wakita T. Production and characterization of HCV particles from serum-free culture. Vaccine 2011; 29:4821-8. [PMID: 21550372 DOI: 10.1016/j.vaccine.2011.04.069] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 04/08/2011] [Accepted: 04/19/2011] [Indexed: 01/02/2023]
Abstract
Hepatitis C virus (HCV) is a major cause of liver cancer, and it is therefore important to develop a prophylactic strategy for HCV infection. In recent years, a system for cell culture of the infectious HCV particle has been established, and the inactivated particle has potential as an antigen for vaccine development. In this study, we aimed to establish highly efficient HCV particle purification procedures using the following serum-free culture of HCV particles. First, naïve human hepatoma Huh7 cells were grown in serum-free medium that was supplemented with human-derived insulin, transferrin and sodium selenite. Then, in vitro transcribed JFH-1 or J6/JFH-1 chimeric HCV-RNA was transfected into the serum-free conditioned Huh7 cells. Infectious HCV was secreted into the culture supernatant with the same efficiency as that from cells cultured in FBS-containing medium. The HCV-core protein and RNA continued to be detected in the culture supernatant when the infected cells were subcultured in serum-free medium. Sucrose gradient centrifugation analyses indicated that the profiles of HCV-core, HCV-RNA and the infectivity of HCV particles were almost identical between HCV from FBS-supplemented and serum-free cultures. We further determined that anti-CD81, anti-SR-BI and anti-E2 antibodies inhibited infection by serum-free cultured HCV to a greater extent than infection by HCV from FBS-supplemented cultures. These HCV particles also differed in the level of associated apoplipoproteins: the ApoE level was lower in serum-free cultured HCV. ApoB and ApoE antibody-depletion assays suggested that infection of serum-free cultured HCV was independent of ApoB and ApoE proteins. These data suggest that lipids conjugated with HCV affect infection and neutralization.
Collapse
Affiliation(s)
- Daisuke Akazawa
- Pharmaceutical Research Laboratories, Toray Industries, Inc., Kanagawa, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Amako Y, Syed GH, Siddiqui A. Protein kinase D negatively regulates hepatitis C virus secretion through phosphorylation of oxysterol-binding protein and ceramide transfer protein. J Biol Chem 2011; 286:11265-74. [PMID: 21285358 DOI: 10.1074/jbc.m110.182097] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hepatitis C virus (HCV) RNA replicates its genome on specialized endoplasmic reticulum modified membranes termed membranous web and utilizes lipid droplets for initiating the viral nucleocapsid assembly. HCV maturation and/or the egress pathway requires host sphingolipid synthesis, which occur in the Golgi. Ceramide transfer protein (CERT) and oxysterol-binding protein (OSBP) play a crucial role in sphingolipid biosynthesis. Protein kinase D (PKD), a serine/threonine kinase, is recruited to the trans-Golgi network where it influences vesicular trafficking to the plasma membrane by regulation of several important mediators via phosphorylation. PKD attenuates the function of both CERT and OSBP by phosphorylation at their respective Ser(132) and Ser(240) residues (phosphorylation inhibition). Here, we investigated the functional role of PKD in HCV secretion. Our studies show that HCV gene expression down-regulated PKD activation. PKD depletion by shRNA or inhibition by pharmacological inhibitor Gö6976 enhanced HCV secretion. Overexpression of a constitutively active form of PKD suppressed HCV secretion. The suppression by PKD was subverted by the ectopic expression of nonphosphorylatable serine mutant CERT S132A or OSBP S240A. These observations imply that PKD negatively regulates HCV secretion/release by attenuating OSBP and CERT functions by phosphorylation inhibition. This study identifies the key role of the Golgi components in the HCV maturation process.
Collapse
Affiliation(s)
- Yutaka Amako
- Department of Medicine, Division of Infectious Diseases, Moores Cancer Center, University of California, San Diego, La Jolla, California 92093, USA
| | | | | |
Collapse
|
35
|
Bartenschlager R, Penin F, Lohmann V, André P. Assembly of infectious hepatitis C virus particles. Trends Microbiol 2010; 19:95-103. [PMID: 21146993 DOI: 10.1016/j.tim.2010.11.005] [Citation(s) in RCA: 298] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 11/08/2010] [Accepted: 11/12/2010] [Indexed: 02/07/2023]
Abstract
A hallmark of the hepatitis C virus (HCV) replication cycle is its tight link with host cell lipid synthesis. This is best illustrated by the peculiar pathway used for the assembly of infectious HCV particles. Research in the past few years has shown that formation of HC-virions is closely connected to lipid droplets that could serve as an assembly platform. Moreover, HCV particle production appears to be strictly linked to very-low-density lipoproteins. In this review, we focus on new insights into the molecular aspects of the architecture and assembly of this unique type of virus particle.
Collapse
Affiliation(s)
- Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Im Neuenheimer Feld 345, Heidelberg University, D-69120 Heidelberg, Germany.
| | | | | | | |
Collapse
|
36
|
Merz A, Long G, Hiet MS, Brügger B, Chlanda P, Andre P, Wieland F, Krijnse-Locker J, Bartenschlager R. Biochemical and morphological properties of hepatitis C virus particles and determination of their lipidome. J Biol Chem 2010; 286:3018-32. [PMID: 21056986 DOI: 10.1074/jbc.m110.175018] [Citation(s) in RCA: 281] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A hallmark of hepatitis C virus (HCV) particles is their association with host cell lipids, most notably lipoprotein components. It is thought that this property accounts for the low density of virus particles and their large heterogeneity. However, the composition of infectious virions and their biochemical and morphological properties are largely unknown. We developed a system in which the envelope glycoprotein E2 was N-terminally tagged with a FLAG epitope. This virus, designated Jc1E2(FLAG), produced infectivity titers to wild type levels and allowed affinity purification of virus particles that were analyzed for their protein and lipid composition. By using mass spectrometry, we found the lipid composition of Jc1E2(FLAG) particles to resemble the one very low- and low density-lipoprotein with cholesteryl esters accounting for almost half of the total HCV lipids. Thus, HCV particles possess a unique lipid composition that is very distinct from all other viruses analyzed so far and from the human liver cells in which HCV was produced. By electron microscopy (EM), we found purified Jc1E2(FLAG) particles to be heterogeneous, mostly spherical structures, with an average diameter of about 73 nm. Importantly, the majority of E2-containing particles also contained apoE on their surface as assessed by immuno-EM. Taken together, we describe a rapid and efficient system for the production of large quantities of affinity-purified HCV allowing a comprehensive analysis of the infectious virion, including the determination of its lipid composition.
Collapse
Affiliation(s)
- Andreas Merz
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
37
|
Felmlee DJ, Sheridan DA, Bridge SH, Nielsen SU, Milne RW, Packard CJ, Caslake MJ, McLauchlan J, Toms GL, Neely RDG, Bassendine MF. Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles. Gastroenterology 2010; 139:1774-83, 1783.e1-6. [PMID: 20682323 DOI: 10.1053/j.gastro.2010.07.047] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 06/28/2010] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS The physical association of hepatitis C virus (HCV) particles with lipoproteins in plasma results in distribution of HCV in a broad range of buoyant densities. This association is thought to increase virion infectivity by mediating cell entry via lipoprotein receptors. We sought to determine if factors that affect triglyceride-rich lipoprotein (TRL) metabolism alter the density and dynamics of HCV particles in the plasma of patients with chronic HCV infection. METHODS Fasting patients (n = 10) consumed a high-fat milkshake; plasma was collected and fractionated by density gradients. HCV- RNA was measured in the very-low-density fraction (VLDF, d < 1.025 g/mL) before and at 7 serial time points postprandially. RESULTS The amount of HCV RNA in the VLDF (HCV(VLDF)) increased a mean of 26-fold, peaking 180 minutes after the meal (P < .01). Quantification of HCV RNA throughout the density gradient fractions revealed that HCV(VLDF) rapidly disappeared, rather than migrating into the adjacent density fraction. Immuno-affinity separation of the VLDF, using antibodies that recognize apolipoprotein B-100 and not apolipoprotein B-48, showed that HCV(VLDF) is composed of chylomicron- and VLDL-associated HCV particles; peaking 120 and 180 minutes after the meal, respectively. Plasma from fasting HCV-infected patients mixed with uninfected plasma increased the quantity of HCV(VLDF), compared with that mixed with phosphate-buffered saline, showing extracellular assembly of HCV(VLDF). CONCLUSIONS Dietary triglyceride alters the density and dynamics of HCV in plasma. The rapid clearance rate of HCV(VLDF) indicates that association with TRL is important for HCV infectivity. HCV particles, such as exchangeable apolipoproteins, appear to reassociate with TRLs in the vascular compartment.
Collapse
Affiliation(s)
- Daniel J Felmlee
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Interaction of the hepatitis C virus (HCV) core with cellular genes in the development of HCV-induced steatosis. Arch Virol 2010; 155:1735-53. [DOI: 10.1007/s00705-010-0797-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 08/31/2010] [Indexed: 12/13/2022]
|
39
|
Jones DM, McLauchlan J. Hepatitis C virus: assembly and release of virus particles. J Biol Chem 2010; 285:22733-9. [PMID: 20457608 DOI: 10.1074/jbc.r110.133017] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Hepatitis C virus is a blood-borne virus that typically establishes a chronic infection in the liver, which often results in cirrhosis and hepatocellular carcinoma. Progress in understanding the complete virus life cycle has been greatly enhanced by the recent availability of a tissue culture system that produces infectious virus progeny. Thus, it is now possible to gain insight into the roles played by viral components in assembly and egress and the cellular pathways that contribute to virion formation. This minireview describes the key determining viral and host factors that are needed to produce infectious virus.
Collapse
Affiliation(s)
- Daniel M Jones
- Medical Research Council Virology Unit, Church Street, Glasgow G11 5JR, Scotland, United Kingdom
| | | |
Collapse
|
40
|
Bartosch B, Dubuisson J. Recent advances in hepatitis C virus cell entry. Viruses 2010; 2:692-709. [PMID: 21994653 PMCID: PMC3185649 DOI: 10.3390/v2030692] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/04/2010] [Accepted: 03/05/2010] [Indexed: 12/15/2022] Open
Abstract
More than 170 million patients worldwide are chronically infected with hepatitis C virus (HCV). Prevalence rates range from 0.5% in Northern European countries to 28% in some areas of Egypt. HCV is hepatotropic, and in many countries chronic hepatitis C is a leading cause of liver disease including fibrosis, cirrhosis and hepatocellular carcinoma. HCV persists in 50-85% of infected patients, and once chronic infection is established, spontaneous clearance is rare. HCV is a member of the Flaviviridae family, in which it forms its own genus. Many lines of evidence suggest that the HCV life cycle displays many differences to that of other Flaviviridae family members. Some of these differences may be due to the close interaction of HCV with its host's lipid and particular triglyceride metabolism in the liver, which may explain why the virus can be found in association with lipoproteins in serum of infected patients. This review focuses on the molecular events underlying the HCV cell entry process and the respective roles of cellular co-factors that have been implied in these events. These include, among others, the lipoprotein receptors low density lipoprotein receptor and scavenger receptor BI, the tight junction factors occludin and claudin-1 as well as the tetraspanin CD81. We discuss the roles of these cellular factors in HCV cell entry and how association of HCV with lipoproteins may modulate the cell entry process.
Collapse
Affiliation(s)
- Birke Bartosch
- INSERM, U871, 69003 Lyon, France
- Université Lyon 1, IFR62 Lyon-Est, 69008 Lyon, France
- Hospices Civils de Lyon, Hôtel Dieu, Service d’hépatologie et de gastroentérologie, 69002 Lyon, France
| | - Jean Dubuisson
- Université Lille Nord de France, F-59000 Lille, France; E-Mail: (J.D.)
- CNRS, Institut de Biologie de Lille (UMR8161), F-59021 Lille, France
- Institut Pasteur de Lille, F-59019 Lille, France
| |
Collapse
|
41
|
Guevara J, Prashad N, Ermolinsky B, Gaubatz JW, Kang D, Schwarzbach AE, Loose DS, Guevara NV. Apo B100 similarities to viral proteins suggest basis for LDL-DNA binding and transfection capacity. J Lipid Res 2010; 51:1704-18. [PMID: 20173184 DOI: 10.1194/jlr.m003277] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
LDL mediates transfection with plasmid DNA in a variety of cell types in vitro and in several tissues in vivo in the rat. The transfection capacity of LDL is based on apo B100, as arginine/lysine clusters, suggestive of nucleic acid-binding domains and nuclear localization signal sequences, are present throughout the molecule. Apo E may also contribute to this capacity because of its similarity to the Dengue virus capsid proteins and its ability to bind DNA. Synthetic peptides representing two apo B100 regions with prominent Arg/Lys clusters were shown to bind DNA. Region 1 (0014Lys-Ser0160) shares sequence motifs present in DNA binding domains of Interferon Regulatory Factors and Flaviviridae capsid/core proteins. It also contains a close analog of the B/E receptor ligand of apo E. Region 1 peptides, B1-1 (0014Lys-Glu0054) and B1-2 (0055Leu-Ala0096), mediate transfection of HeLa cells but are cytotoxic. Region 2 (3313Asp-Thr3431), containing the known B/E receptor ligand, shares analog motifs with the human herpesvirus 5 immediate-early transcriptional regulator (UL122) and Flaviviridae NS3 helicases. Region 2 peptides, B2-1 (3313Asp-Glu3355), and B2-2 (3356Gly-Thr3431) are ineffective in cell transfection and are noncytotoxic. These results confirm the role of LDL as a natural transfection vector in vivo, a capacity imparted by the apo B100, and suggest a basis for Flaviviridae cell entry.
Collapse
Affiliation(s)
- Juan Guevara
- Department of Physics and Astronomy, University of Texas Brownsville/Texas Southmost College, Brownsville, TX 78520, USA
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Syed GH, Amako Y, Siddiqui A. Hepatitis C virus hijacks host lipid metabolism. Trends Endocrinol Metab 2010; 21:33-40. [PMID: 19854061 PMCID: PMC2818172 DOI: 10.1016/j.tem.2009.07.005] [Citation(s) in RCA: 273] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2009] [Revised: 07/17/2009] [Accepted: 07/24/2009] [Indexed: 12/19/2022]
Abstract
Hepatitis C virus (HCV) enhances its replication by modulating host cell lipid metabolism. HCV circulates in the blood in association with lipoproteins. HCV infection is associated with enhanced lipogenesis, reduced secretion, and beta-oxidation of lipids. HCV-induced imbalance in lipid homeostasis leads to steatosis. Many lipids are crucial for the virus life cycle, and inhibitors of cholesterol/fatty acid biosynthetic pathways inhibit virus replication, maturation and secretion. HCV negatively modulates the synthesis and secretion of very low-density lipoproteins (VLDL). Components involved in VLDL assembly are also required for HCV morphogenesis/secretion, suggesting that HCV co-opts the VLDL secretory pathway for its own secretion. This review highlights HCV-altered lipid metabolic events that aid the virus life cycle and ultimately promote liver disease.
Collapse
|
43
|
Apolipoprotein E but not B is required for the formation of infectious hepatitis C virus particles. J Virol 2009; 83:12680-91. [PMID: 19793818 DOI: 10.1128/jvi.01476-09] [Citation(s) in RCA: 206] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Our previous studies have found that hepatitis C virus (HCV) particles are enriched in apolipoprotein E (apoE) and that apoE is required for HCV infectivity and production. Studies by others, however, suggested that both microsomal transfer protein (MTP) and apoB are important for HCV production. To define the roles of apoB and apoE in the HCV life cycle, we developed a single-cycle HCV growth assay to determine the correlation of HCV assembly with apoB and apoE expression, as well as the influence of MTP inhibitors on the formation of HCV particles. The small interfering RNA (siRNA)-mediated knockdown of apoE expression remarkably suppressed the formation of HCV particles. However, apoE expressed ectopically could restore the defect of HCV production posed by the siRNA-mediated knockdown of endogenous apoE expression. In contrast, apoB-specific antibodies and siRNAs had no significant effect on HCV infectivity and production, respectively, suggesting that apoB does not play a significant role in the HCV life cycle. Additionally, two MTP inhibitors, CP-346086 and BMS-2101038, efficiently blocked secretion of apoB-containing lipoproteins but did not affect HCV production unless apoE expression and secretion were inhibited. At higher concentrations, however, MTP inhibitors blocked apoE expression and secretion and consequently suppressed the formation of HCV particles. Furthermore, apoE was found to be sensitive to trypsin digestion and to interact with NS5A in purified HCV particles and HCV-infected cells, as demonstrated by coimmunoprecipitation. Collectively, these findings demonstrate that apoE but not apoB is required for HCV assembly, probably via a specific interaction with NS5A.
Collapse
|
44
|
Icard V, Diaz O, Scholtes C, Perrin-Cocon L, Ramière C, Bartenschlager R, Penin F, Lotteau V, André P. Secretion of hepatitis C virus envelope glycoproteins depends on assembly of apolipoprotein B positive lipoproteins. PLoS One 2009; 4:e4233. [PMID: 19156195 PMCID: PMC2617766 DOI: 10.1371/journal.pone.0004233] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 12/03/2008] [Indexed: 01/07/2023] Open
Abstract
The density of circulating hepatitis C virus (HCV) particles in the blood of chronically infected patients is very heterogeneous. The very low density of some particles has been attributed to an association of the virus with apolipoprotein B (apoB) positive and triglyceride rich lipoproteins (TRL) likely resulting in hybrid lipoproteins known as lipo-viro-particles (LVP) containing the viral envelope glycoproteins E1 and E2, capsid and viral RNA. The specific infectivity of these particles has been shown to be higher than the infectivity of particles of higher density. The nature of the association of HCV particles with lipoproteins remains elusive and the role of apolipoproteins in the synthesis and assembly of the viral particles is unknown. The human intestinal Caco-2 cell line differentiates in vitro into polarized and apoB secreting cells during asymmetric culture on porous filters. By using this cell culture system, cells stably expressing E1 and E2 secreted the glycoproteins into the basal culture medium after one week of differentiation concomitantly with TRL secretion. Secreted glycoproteins were only detected in apoB containing density fractions. The E1-E2 and apoB containing particles were unique complexes bearing the envelope glycoproteins at their surface since apoB could be co-immunoprecipitated with E2-specific antibodies. Envelope protein secretion was reduced by inhibiting the lipidation of apoB with an inhibitor of the microsomal triglyceride transfer protein. HCV glycoproteins were similarly secreted in association with TRL from the human liver cell line HepG2 but not by Huh-7 and Huh-7.5 hepatoma cells that proved deficient for lipoprotein assembly. These data indicate that HCV envelope glycoproteins have the intrinsic capacity to utilize apoB synthesis and lipoprotein assembly machinery even in the absence of the other HCV proteins. A model for LVP assembly is proposed.
Collapse
Affiliation(s)
- Vinca Icard
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
- Hospices Civils de Lyon, Laboratoire de Virologie Nord, Lyon, France
| | - Olivier Diaz
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
| | - Caroline Scholtes
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
- Hospices Civils de Lyon, Laboratoire de Virologie Nord, Lyon, France
| | - Laure Perrin-Cocon
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
| | - Christophe Ramière
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
- Hospices Civils de Lyon, Laboratoire de Virologie Nord, Lyon, France
| | - Ralf Bartenschlager
- Department of Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Francois Penin
- CNRS, UMR 5086, Institut de Biologie et Chimie des Protéines, Lyon, France
| | - Vincent Lotteau
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
- Hospices Civils de Lyon, Laboratoire de Virologie Nord, Lyon, France
| | - Patrice André
- Université de Lyon, Lyon, France
- Inserm, U851, Lyon, France
- Université de Lyon1, IFR128 BioSciences Lyon-Gerland, Lyon, France
- Hospices Civils de Lyon, Laboratoire de Virologie Nord, Lyon, France
- * E-mail:
| |
Collapse
|
45
|
Lipid droplets and hepatitis C virus infection. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1791:552-9. [PMID: 19167518 DOI: 10.1016/j.bbalip.2008.12.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 11/25/2008] [Accepted: 12/23/2008] [Indexed: 02/06/2023]
Abstract
Lipid droplets play an important part in the life cycle of hepatitis C virus and also are markers for steatosis, which is a common condition that arises during infection. These storage organelles are targeted by the viral core protein, which forms the capsid shell. Attachment of core to lipid droplets requires a C-terminal domain within the protein that is highly conserved between different virus isolates. In infected cells, the presence of core on lipid droplets creates loci that contain viral RNA and non-structural proteins involved in genome replication. Such locations may represent sites for initiating assembly and production of nascent virions. In addition to utilising lipid droplets as part the virus life cycle, hepatitis C virus induces their accumulation in infected hepatocytes. The mechanisms involved in this process are not understood but evidence from patient-based studies and model systems suggests the involvement of both viral and host factors.
Collapse
|