1
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Dwivedi M, Dwivedi A, Mukherjee D. An Insight into Hepatitis C Virus: In Search of Promising Drug Targets. Curr Drug Targets 2023; 24:1127-1138. [PMID: 37907492 DOI: 10.2174/0113894501265769231020031857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 09/13/2023] [Accepted: 09/21/2023] [Indexed: 11/02/2023]
Abstract
Hepatitis C Virus (HCV) is a global health concern, chronically infecting over 70 million people worldwide. HCV is a bloodborne pathogen that primarily affects the liver, and chronic HCV infection can lead to cirrhosis, liver cancer, and liver failure over time. There is an urgent need for more effective approaches to prevent and treat HCV. This review summarizes current knowledge on the virology, transmission, diagnosis, and management of HCV infection. It also provides an in-depth analysis of HCV proteins as promising targets for antiviral drug and vaccine development. Specific HCV proteins discussed as potential drug targets include the NS5B polymerase, NS3/4A protease, entry receptors like CD81, and core proteins. The implications of HCV proteins as diagnostic and prognostic biomarkers are also explored. Current direct-acting antiviral therapies are effective but have cost, genotype specificity, and resistance limitations. This review aims to synthesize essential information on HCV biology and pathogenesis to inform future research on improved preventive, diagnostic, and therapeutic strategies against this global infectious disease threat.
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Affiliation(s)
- Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Gomtinagar Extension, Lucknow- 226028, India
| | - Aditya Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Gomtinagar Extension, Lucknow- 226028, India
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2
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Breitinger U, Farag NS, Ali NKM, Ahmed M, El-Azizi MA, Breitinger HG. Cell viability assay as a tool to study activity and inhibition of hepatitis C p7 channels. J Gen Virol 2021; 102. [PMID: 33709903 DOI: 10.1099/jgv.0.001571] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The p7 viroporin of the hepatitis C virus (HCV) forms an intracellular proton-conducting transmembrane channel in virus-infected cells, shunting the pH of intracellular compartments and thus helping virus assembly and release. This activity is essential for virus infectivity, making viroporins an attractive target for drug development. The protein sequence and drug sensitivity of p7 vary between the seven major genotypes of the hepatitis C virus, but the essential channel activity is preserved. Here, we investigated the effect of several inhibitors on recombinant HCV p7 channels corresponding to genotypes 1a-b, 2a-b, 3a and 4a using patch-clamp electrophysiology and cell-based assays. We established a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-based cell viability assay for recombinant p7 expressed in HEK293 cells to assess channel activity and its sensitivity to inhibitors. The results from the cell viability assay were consistent with control measurements using established assays of haemadsorption and intracellular pH, and agreed with data from patch-clamp electrophysiology. Hexamethylene amiloride (HMA) was the most potent inhibitor of p7 activity, but possessed cytotoxic activity at higher concentrations. Rimantadine was active against p7 of all genotypes, while amantadine activity was genotype-dependent. The alkyl-chain iminosugars NB-DNJ, NN-DNJ and NN-DGJ were tested and their activity was found to be genotype-specific. In the current study, we introduce cell viability assays as a rapid and cost-efficient technique to assess viroporin activity and identify channel inhibitors as potential novel antiviral drugs.
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Affiliation(s)
- Ulrike Breitinger
- Department of Biochemistry, German University in Cairo, New Cairo, Egypt
| | - Noha S Farag
- Department of Microbiology and Immunology, German University in Cairo, New Cairo, Egypt
| | - Nourhan K M Ali
- Department of Biochemistry, German University in Cairo, New Cairo, Egypt
| | - Marwa Ahmed
- Present address: Institute of Biochemistry and Biophysics Friedrich-Schiller-University Jena, Hans-Knöll-Str. 2, D-07745, Jena, Germany.,Department of Biochemistry, German University in Cairo, New Cairo, Egypt
| | - Mohamed A El-Azizi
- Department of Microbiology and Immunology, German University in Cairo, New Cairo, Egypt
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3
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Koutsoumpli G, Ip PP, Schepel I, Hoogeboom BN, Boerma A, Daemen T. Alphavirus-based hepatitis C virus therapeutic vaccines: can universal helper epitopes enhance HCV-specific cytotoxic T lymphocyte responses? Ther Adv Vaccines Immunother 2019; 7:2515135519874677. [PMID: 31620673 PMCID: PMC6777054 DOI: 10.1177/2515135519874677] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/31/2019] [Indexed: 12/28/2022] Open
Abstract
Background: Antigen-specific T cell immune responses play a pivotal role in resolving
acute and chronic hepatitis C virus (HCV) infections. Currently, no
prophylactic or therapeutic vaccines against HCV are available. We
previously demonstrated the preclinical potency of therapeutic HCV vaccines
based on recombinant Semliki Forest virus (SFV) replicon particles. However,
clinical trials do not always meet the high expectations of preclinical
studies, thus, optimization of vaccine strategies is crucial. In efforts to
further increase the frequency of HCV-specific immune responses in the
candidate SFV-based vaccines, the authors assessed whether inclusion of
three strong, so-called universal helper T cell epitopes, and an endoplasmic
reticulum localization, and retention signal (collectively termed
sigHELP-KDEL cassette) could enhance HCV-specific immune responses. Methods: We included the sigHELP-KDEL cassette in two of the candidate SFV-based HCV
vaccines, targeting NS3/4A and NS5A/B proteins. We characterized the new
constructs in vitro for the expression and stability of the
transgene-encoded proteins. Their immune efficacy with respect to
HCV-specific immune responses in vivo was compared with the
parental SFV vaccine expressing the corresponding HCV antigen. Further
characterization of the functionality of the HCV-specific CD8+ T
cells was assessed by surface and intracellular cytokine staining and flow
cytometry analysis. Results: Moderate, but significantly, enhanced frequencies of antigen-specific immune
responses were achieved upon lower/suboptimal dosage immunization. In
optimal dosage immunization, the inclusion of the cassette did not further
increase the frequencies of HCV-specific CD8+ T cells when
compared with the parental vaccines and the frequencies of effector and
memory populations were identical. Conclusion: We hypothesize that the additional effect of the sigHELP-KDEL cassette in
SFV-based vaccines depends on the immunogenicity, nature, and stability of
the target antigen expressed by the vaccine.
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Affiliation(s)
- Georgia Koutsoumpli
- Department of Medical Microbiology, Tumor Virology and Cancer Immunotherapy, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Peng Peng Ip
- Department of Medical Microbiology, Tumor Virology and Cancer Immunotherapy, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Ilona Schepel
- Department of Medical Microbiology, Tumor Virology and Cancer Immunotherapy, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Baukje Nynke Hoogeboom
- Department of Medical Microbiology, Tumor Virology and Cancer Immunotherapy, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Annemarie Boerma
- Department of Medical Microbiology, Tumor Virology and Cancer Immunotherapy, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Toos Daemen
- Department of Medical Microbiology, Tumor Virology and Cancer Immunotherapy, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen, 9713 AV, the Netherlands
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4
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Soranzo T, Martin DK, Lenormand JL, Watkins EB. Coupling neutron reflectivity with cell-free protein synthesis to probe membrane protein structure in supported bilayers. Sci Rep 2017; 7:3399. [PMID: 28611396 PMCID: PMC5469739 DOI: 10.1038/s41598-017-03472-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/16/2017] [Indexed: 01/01/2023] Open
Abstract
The structure of the p7 viroporin, an oligomeric membrane protein ion channel involved in the assembly and release of the hepatitis C virus, was determined from proteins expressed and inserted directly into supported model lipid membranes using cell-free protein expression. Cell-free protein expression allowed (i ) high protein concentration in the membrane, (ii ) control of the protein's isotopic constitution, and (iii ) control over the lipid environment available to the protein. Here, we used cell-free protein synthesis to directly incorporate the hepatitis C virus (HCV) p7 protein into supported lipid bilayers formed from physiologically relevant lipids (POPC or asolectin) for both direct structural measurements using neutron reflectivity (NR) and conductance measurements using electrical impedance spectroscopy (EIS). We report that HCV p7 from genotype 1a strain H77 adopts a conical shape within lipid bilayers and forms a viroporin upon oligomerization, confirmed by EIS conductance measurements. This combination of techniques represents a novel approach to the study of membrane proteins and, through the use of selective deuteration of particular amino acids to enhance neutron scattering contrast, has the promise to become a powerful tool for characterizing the protein conformation in physiologically relevant environments and for the development of biosensor applications.
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Affiliation(s)
- Thomas Soranzo
- Synthelis SAS, 5 avenue du Grand Sablon, 38700, La Tronche, France
- University Grenoble Alpes, TheREx, TIMC IMAG/CNRS, UMR 5525, F-38000, Grenoble, France
| | - Donald K Martin
- University Grenoble Alpes, SyNaBi, TIMC IMAG/CNRS, UMR 5525, F-38000, Grenoble, France
| | - Jean-Luc Lenormand
- University Grenoble Alpes, TheREx, TIMC IMAG/CNRS, UMR 5525, F-38000, Grenoble, France
| | - Erik B Watkins
- Institut Laue-Langevin, 6 rue Jules Horowitz, BP 156, 38042, Grenoble, Cedex 9, France.
- MPA-11: Materials Synthesis and Integrated Devices, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.
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5
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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.
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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
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6
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Palmitoylation of Sindbis Virus TF Protein Regulates Its Plasma Membrane Localization and Subsequent Incorporation into Virions. J Virol 2017; 91:JVI.02000-16. [PMID: 27852864 DOI: 10.1128/jvi.02000-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/13/2016] [Indexed: 01/20/2023] Open
Abstract
Palmitoylation is a reversible, posttranslational modification that helps target proteins to cellular membranes. The alphavirus small membrane proteins 6K and TF have been reported to be palmitoylated and to positively regulate budding. 6K and TF are isoforms that are identical in their N termini but unique in their C termini due to a -1 ribosomal frameshift during translation. In this study, we used cysteine (Cys) mutants to test differential palmitoylation of the Sindbis virus 6K and TF proteins. We modularly mutated the five Cys residues in the identical N termini of 6K and TF, the four additional Cys residues in TF's unique C terminus, or all nine Cys residues in TF. Using these mutants, we determined that TF palmitoylation occurs primarily in the N terminus. In contrast, 6K is not palmitoylated, even on these shared residues. In the C-terminal Cys mutant, TF protein levels increase both in the cell and in the released virion compared to the wild type. In viruses with the N-terminal Cys residues mutated, TF is much less efficiently localized to the plasma membrane, and it is not incorporated into the virion. The three Cys mutants have minor defects in cell culture growth but a high incidence of abnormal particle morphologies compared to the wild-type virus as determined by transmission electron microscopy. We propose a model where the C terminus of TF modulates the palmitoylation of TF at the N terminus, and palmitoylated TF is preferentially trafficked to the plasma membrane for virus budding. IMPORTANCE Alphaviruses are a reemerging viral cause of arthritogenic disease. Recently, the small 6K and TF proteins of alphaviruses were shown to contribute to virulence in vivo Nevertheless, a clear understanding of the molecular mechanisms by which either protein acts to promote virus infection is missing. The TF protein is a component of budded virions, and optimal levels of TF correlate positively with wild-type-like particle morphology. In this study, we show that the palmitoylation of TF regulates its localization to the plasma membrane, which is the site of alphavirus budding. Mutants in which TF is not palmitoylated display drastically reduced plasma membrane localization, which effectively prevents TF from participating in budding or being incorporated into virus particles. Investigation of the regulation of TF will aid current efforts in the alphavirus field searching for approaches to mitigate alphaviral disease in humans.
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7
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Rojas Á, Del Campo JA, Clement S, Lemasson M, García-Valdecasas M, Gil-Gómez A, Ranchal I, Bartosch B, Bautista JD, Rosenberg AR, Negro F, Romero-Gómez M. Effect of Quercetin on Hepatitis C Virus Life Cycle: From Viral to Host Targets. Sci Rep 2016; 6:31777. [PMID: 27546480 PMCID: PMC4992894 DOI: 10.1038/srep31777] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 07/26/2016] [Indexed: 12/13/2022] Open
Abstract
Quercetin is a natural flavonoid, which has been shown to have anti hepatitis C virus (HCV) properties. However, the exact mechanisms whereby quercetin impacts the HCV life cycle are not fully understood. We assessed the effect of quercetin on different steps of the HCV life cycle in Huh-7.5 cells and primary human hepatocytes (PHH) infected with HCVcc. In both cell types, quercetin significantly decreased i) the viral genome replication; ii) the production of infectious HCV particles and iii) the specific infectivity of the newly produced viral particles (by 85% and 92%, Huh7.5 and PHH respectively). In addition, when applied directly on HCV particles, quercetin reduced their infectivity by 65%, suggesting that it affects the virion integrity. Interestingly, the HCV-induced up-regulation of diacylglycerol acyltransferase (DGAT) and the typical localization of the HCV core protein to the surface of lipid droplets, known to be mediated by DGAT, were both prevented by quercetin. In conclusion, quercetin appears to have direct and host-mediated antiviral effects against HCV.
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Affiliation(s)
- Ángela Rojas
- UCM Digestive Diseases, Virgen Macarena-Virgen del Rocío University Hospitals and CIBERehd, Institute of Biomedicine, University of Sevilla, Sevilla, Spain.,Unit for the Clinical Management of Digestive Diseases, Hospital Universitario Valme de Sevilla, Sevilla, Spain
| | - Jose A Del Campo
- Unit for the Clinical Management of Digestive Diseases, Hospital Universitario Valme de Sevilla, Sevilla, Spain
| | - Sophie Clement
- Division of Clinical Pathology, University Hospital, Geneva, Switzerland
| | | | - Marta García-Valdecasas
- UCM Digestive Diseases, Virgen Macarena-Virgen del Rocío University Hospitals and CIBERehd, Institute of Biomedicine, University of Sevilla, Sevilla, Spain.,Unit for the Clinical Management of Digestive Diseases, Hospital Universitario Valme de Sevilla, Sevilla, Spain
| | - Antonio Gil-Gómez
- UCM Digestive Diseases, Virgen Macarena-Virgen del Rocío University Hospitals and CIBERehd, Institute of Biomedicine, University of Sevilla, Sevilla, Spain.,Unit for the Clinical Management of Digestive Diseases, Hospital Universitario Valme de Sevilla, Sevilla, Spain
| | - Isidora Ranchal
- Unit for the Clinical Management of Digestive Diseases, Hospital Universitario Valme de Sevilla, Sevilla, Spain
| | - Birke Bartosch
- Inserm U1052, Cancer Research Centre, University of Lyon, France DevWeCan Laboratories of Excellence Network (Labex), Lyon, France
| | - Juan D Bautista
- Biochemistry and Molecular Biology, Faculty of Pharmacy, University of Sevilla, Spain
| | | | - Francesco Negro
- Division of Clinical Pathology, University Hospital, Geneva, Switzerland.,Division of Gastroenterology and Hepatology, University Hospital, Geneva, Switzerland
| | - Manuel Romero-Gómez
- UCM Digestive Diseases, Virgen Macarena-Virgen del Rocío University Hospitals and CIBERehd, Institute of Biomedicine, University of Sevilla, Sevilla, Spain
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8
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Winer BY, Ding Q, Gaska JM, Ploss A. In vivo models of hepatitis B and C virus infection. FEBS Lett 2016; 590:1987-99. [PMID: 27009462 DOI: 10.1002/1873-3468.12157] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/16/2016] [Accepted: 03/22/2016] [Indexed: 12/17/2022]
Abstract
Globally, more than 500 million individuals are chronically infected with hepatitis B (HBV), delta (HDV), and/or C (HCV) viruses, which can result in severe liver disease. Mechanistic studies of viral persistence and pathogenesis have been hampered by the scarcity of animal models. The limited species and cellular host range of HBV, HDV, and HCV, which robustly infect only humans and chimpanzees, have posed challenges for creating such animal models. In this review, we will discuss the barriers to interspecies transmission and the progress that has been made in our understanding of the HBV, HDV, and HCV life cycles. Additionally, we will highlight a variety of approaches that overcome these barriers and thus facilitate in vivo studies of these hepatotropic viruses.
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Affiliation(s)
| | - Qiang Ding
- Department of Molecular Biology, Princeton University, NJ, USA
| | - Jenna M Gaska
- Department of Molecular Biology, Princeton University, NJ, USA
| | - Alexander Ploss
- Department of Molecular Biology, Princeton University, NJ, USA
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9
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Eggert D, Rösch K, Reimer R, Herker E. Visualization and analysis of hepatitis C virus structural proteins at lipid droplets by super-resolution microscopy. PLoS One 2014; 9:e102511. [PMID: 25019511 PMCID: PMC4094509 DOI: 10.1371/journal.pone.0102511] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/19/2014] [Indexed: 12/17/2022] Open
Abstract
Cytosolic lipid droplets are central organelles in the Hepatitis C Virus (HCV) life cycle. The viral capsid protein core localizes to lipid droplets and initiates the production of viral particles at lipid droplet–associated ER membranes. Core is thought to encapsidate newly synthesized viral RNA and, through interaction with the two envelope proteins E1 and E2, bud into the ER lumen. Here, we visualized the spatial distribution of HCV structural proteins core and E2 in vicinity of small lipid droplets by three-color 3D super-resolution microscopy. We observed and analyzed small areas of colocalization between the two structural proteins in HCV-infected cells with a diameter of approximately 100 nm that might represent putative viral assembly sites.
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Affiliation(s)
- Dennis Eggert
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
- Institute of Physical Chemistry, University of Hamburg, Hamburg, Germany
| | - Kathrin Rösch
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
| | - Rudolph Reimer
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
| | - Eva Herker
- Heinrich-Pette-Institute, Leibniz Institute for Experimental Virology, University of Hamburg, Hamburg, Germany
- * E-mail:
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10
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Watashi K. Antiviral agents for analyzing virus life cycle: chemical genetics for virology. YAKUGAKU ZASSHI 2013; 133:1169-75. [PMID: 24189558 DOI: 10.1248/yakushi.13-00212-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hepatitis C virus, which affects approximately 170 million people worldwide, is a major causative agent of hepatocellular carcinoma. Anti-HCV treatment is available with the combination of pegylated interferon and ribavirin, and newly approved protease inhibitors. However, because of the diverse anti-HCV efficacy among HCV genotypes and significant side effects, alternative anti-HCV agents are in great demand. Using cell-based systems supporting a part of or the whole HCV life cycle, we identified cyclosporin A, tamoxifen, and benzamide derivatives that inhibited the replication of HCV RNA or the production of infectious HCV particles. In this article, we summarize the mechanistic analyses of the HCV life cycle using these small molecules. Thus, chemical genetics is a powerful approach for revealing molecular mechanisms of the viral life cycle as well as for developing new antiviral agents.
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Affiliation(s)
- Koichi Watashi
- Department of Virology II, National Institute of Infectious Diseases
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11
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Wang T, Weinman SA. Interactions Between Hepatitis C Virus and Mitochondria: Impact on Pathogenesis and Innate Immunity. CURRENT PATHOBIOLOGY REPORTS 2013; 1:179-187. [PMID: 23956955 DOI: 10.1007/s40139-013-0024-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Hepatitis C virus (HCV) causes a persistent chronic infection of hepatocytes resulting in progressive fibrosis and carcinogenesis. Abnormalities in mitochondria are prominent features of clinical disease where ultrastructural changes, alterations in electron transport, and excess reactive oxygen species (ROS) production occur. These mitochondrial abnormalities correlate with disease severity and resolve with viral eradication. Multiple viral proteins, particularly core and NS3/4a bind to mitochondria. The core and NS5a proteins primarily cause ER stress, ER Ca2+ release and enhance direct transfer of Ca2+ from ER to mitochondria. This results in electron transport changes, increased ROS production and sensitivity to mitochondrial permeability transition and cell death. The viral protease, NS3/4a, binds to mitochondria as well where it cleaves an important signaling adapter, MAVS, thus preventing viral clearance by endogenous interferon production. This review discusses the mechanisms by which HCV causes mitochondrial changes and consequences of these for disease.
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Affiliation(s)
- Ting Wang
- Liver Center and Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66160
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12
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Atoom AM, Jones DM, Russell RS. Evidence suggesting that HCV p7 protects E2 glycoprotein from premature degradation during virus production. Virus Res 2013; 176:199-210. [PMID: 23816605 DOI: 10.1016/j.virusres.2013.06.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 06/14/2013] [Accepted: 06/20/2013] [Indexed: 10/26/2022]
Abstract
The hepatitis C virus (HCV) genome encodes a 63 amino acid (aa) protein, p7, which is located between the structural and non-structural proteins. p7 localizes to endoplasmic reticulum membranes and is composed of two transmembrane domains (TM1 and TM2) and a cytoplasmic loop. While its exact role is unknown, p7 is crucial for assembly and/or release of infectious virus production in cell culture, as well as infectivity in chimpanzees. The contribution of p7 to the HCV life cycle may result from at least two distinct roles. Firstly, several studies have shown that p7 acts as an ion channel, the functionality of which is critical for infection. Secondly, p7 interacts with NS2 in a manner that may regulate the targeting of other structural proteins during the assembly process. In this study, we observed that mutations in TM1 and the cytoplasmic loop of p7 decreased infectious virus production in a single-cycle virus production assay. Analysis of intra- and extracellular virus titers indicated that p7 functions at a stage prior to generation of infectious particles. These effects were not due to altered RNA replication since no effects on levels of NS3 or NS5A protein were observed, and were not a consequence of altered recruitment of core protein to lipid droplets. Similarly, these mutations seemingly did not prevent nucleocapsid oligomerization. Importantly, we found that an alanine triplet substitution including the two basic residues of the cytoplasmic loop, which is integral to p7 ion channel function, significantly reduced E2 glycoprotein levels. A time course experiment tracking E2 levels indicated that E2 was degraded over time, as opposed to being synthesized in reduced quantities. The results of this study provide strong evidence that one of the functions of p7 is to protect HCV glycoproteins from premature degradation during virion morphogenesis.
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Affiliation(s)
- Ali M Atoom
- Immunology and Infectious Diseases, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
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13
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Cell-cell contact-mediated hepatitis C virus (HCV) transfer, productive infection, and replication and their requirement for HCV receptors. J Virol 2013; 87:8545-58. [PMID: 23720720 DOI: 10.1128/jvi.01062-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Hepatitis C virus (HCV) infection is believed to begin with interactions between cell-free HCV and cell receptors that include CD81, scavenger receptor B1 (SR-B1), claudin-1 (CLDN1), and occludin (OCLN). In this study, we have demonstrated that HCV spreading from infected hepatocytes to uninfected hepatocytes leads to the transfer of HCV and the formation of infection foci and is cell density dependent. This cell-cell contact-mediated (CCCM) HCV transfer occurs readily and requires all these known HCV receptors and an intact actin cytoskeleton. With a fluorescently labeled replication-competent HCV system, the CCCM transfer process was further dissected by live-cell imaging into four steps: donor cell-target cell contact, formation of viral puncta-target cell conjugation, transfer of viral puncta, and posttransfer. Importantly, the CCCM HCV transfer leads to productive infection of target cells. Taken together, these results show that CCCM HCV transfer constitutes an important and effective route for HCV infection and dissemination. These findings will aid in the development of new and novel strategies for preventing and treating HCV infection.
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Kim CW, Chang KM. Hepatitis C virus: virology and life cycle. Clin Mol Hepatol 2013; 19:17-25. [PMID: 23593605 PMCID: PMC3622851 DOI: 10.3350/cmh.2013.19.1.17] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 03/15/2012] [Accepted: 03/18/2012] [Indexed: 12/11/2022] Open
Abstract
Hepatitis C virus (HCV) is a positive sense, single-stranded RNA virus in the Flaviviridae family. It causes acute hepatitis with a high propensity for chronic infection. Chronic HCV infection can progress to severe liver disease including cirrhosis and hepatocellular carcinoma. In the last decade, our basic understanding of HCV virology and life cycle has advanced greatly with the development of HCV cell culture and replication systems. Our ability to treat HCV infection has also been improved with the combined use of interferon, ribavirin and small molecule inhibitors of the virally encoded NS3/4A protease, although better therapeutic options are needed with greater antiviral efficacy and less toxicity. In this article, we review various aspects of HCV life cycle including viral attachment, entry, fusion, viral RNA translation, posttranslational processing, HCV replication, viral assembly and release. Each of these steps provides potential targets for novel antiviral therapeutics to cure HCV infection and prevent the adverse consequences of progressive liver disease.
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Affiliation(s)
- Chang Wook Kim
- Department of Internal Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea
| | - Kyong-Mi Chang
- GI/Hepatology Research Center, Philadelphia VA Medical Center, Philadelphia, PA, USA
- Department of Internal Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Vieyres G, Brohm C, Friesland M, Gentzsch J, Wölk B, Roingeard P, Steinmann E, Pietschmann T. Subcellular localization and function of an epitope-tagged p7 viroporin in hepatitis C virus-producing cells. J Virol 2013; 87:1664-78. [PMID: 23175364 PMCID: PMC3554161 DOI: 10.1128/jvi.02782-12] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 11/13/2012] [Indexed: 01/10/2023] Open
Abstract
The hepatitis C virus (HCV) viroporin p7 is crucial for production of infectious viral progeny. However, its role in the viral replication cycle remains incompletely understood, in part due to the poor availability of p7-specific antibodies. To circumvent this obstacle, we inserted two consecutive hemagglutinin (HA) epitope tags at its N terminus. HA-tagged p7 reduced peak virus titers ca. 10-fold and decreased kinetics of virus production compared to the wild-type virus. However, HA-tagged p7 rescued virus production of a mutant virus lacking p7, thus providing formal proof that the tag does not disrupt p7 function. In HCV-producing cells, p7 displayed a reticular staining pattern which colocalized with the HCV envelope glycoprotein 2 (E2) but also partially with viral nonstructural proteins 2, 3, and 5A. Using coimmunoprecipitation, we confirmed a specific interaction between p7 and NS2, whereas we did not detect a stable interaction with core, E2, or NS5A. Moreover, we did not observe p7 incorporation into affinity-purified virus particles. Consistently, there was no evidence supporting a role of p7 in viral entry, as an anti-HA antibody was not able to neutralize Jc1 virus produced from an HA-p7-tagged genome. Collectively, these findings highlight a stable interaction between p7 and NS2 which is likely crucial for production of infectious HCV particles. Use of this functional epitope-tagged p7 variant should facilitate the analysis of the final steps of the HCV replication cycle.
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Affiliation(s)
- Gabrielle Vieyres
- Institute of Experimental Virology, Twincore, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Christiane Brohm
- Institute of Experimental Virology, Twincore, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Martina Friesland
- Institute of Experimental Virology, Twincore, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Juliane Gentzsch
- Institute of Experimental Virology, Twincore, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Benno Wölk
- Institute of Virology, Medical School Hannover, Hannover, Germany
| | - Philippe Roingeard
- INSERM U966, Université François Rabelais, and CHRU de Tours, Tours, France
| | - Eike Steinmann
- Institute of Experimental Virology, Twincore, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Thomas Pietschmann
- Institute of Experimental Virology, Twincore, Centre for Experimental and Clinical Infection Research, a joint venture between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
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Hepatitis C genotype 1 mosaic vaccines are immunogenic in mice and induce stronger T-cell responses than natural strains. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2012; 20:302-5. [PMID: 23221002 DOI: 10.1128/cvi.00605-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Despite improved hepatitis C virus (HCV) treatments, vaccines remain an effective and economic option for curtailing the epidemic. Mosaic protein HCV genotype 1 vaccine candidates designed to address HCV diversity were immunogenic in mice. They elicited stronger T-cell responses to NS3-NS4a and E1-E2 proteins than did natural strains, as assessed with vaccine-matched peptides.
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Karayiannis P. Direct acting antivirals for the treatment of chronic viral hepatitis. SCIENTIFICA 2012; 2012:478631. [PMID: 24278700 PMCID: PMC3820491 DOI: 10.6064/2012/478631] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 10/08/2012] [Indexed: 06/02/2023]
Abstract
The development and evaluation of antiviral agents through carefully designed clinical trials over the last 25 years have heralded a new dawn in the treatment of patients chronically infected with the hepatitis B and C viruses, but not so for the D virus (HBV, HCV, and HDV). The introduction of direct acting antivirals (DDAs) for the treatment of HBV carriers has permitted the long-term use of these compounds for the continuous suppression of viral replication, whilst in the case of HCV in combination with the standard of care [SOC, pegylated interferon (PegIFN), and ribavirin] sustained virological responses (SVRs) have been achieved with increasing frequency. Progress in the case of HDV has been slow and lacking in significant breakthroughs.This paper aims to summarise the current state of play in treatment approaches for chonic viral hepatitis patients and future perspectives.
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Affiliation(s)
- Peter Karayiannis
- Section of Hepatology and Gastroenterology, Department of Medicine, Imperial College, St Mary's Campus, London W2 1PG, UK
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