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Serag A, Alnemari RM, Abduljabbar MH, Alosaimi ME, Almalki AH. Synchronous spectrofluorimetry and chemometric modeling: A synergistic approach for analyzing simeprevir and daclatasvir, with application to pharmacokinetics evaluation. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 315:124245. [PMID: 38581722 DOI: 10.1016/j.saa.2024.124245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 03/30/2024] [Accepted: 04/01/2024] [Indexed: 04/08/2024]
Abstract
Simeprevir and daclatasvir represent a cornerstone in the management of Hepatitis C Virus infection, a global health concern that affects millions of people worldwide. In this study, we propose a synergistic approach combining synchronous spectrofluorimetry and chemometric modeling i.e. Partial Least Squares (PLS-1) for the analysis of simeprevir and daclatasvir in different matrices. Moreover, the study employs firefly algorithms to further optimize the chemometric models via selecting the most informative features thus improving the accuracy and robustness of the calibration models. The firefly algorithm was able to reduce the number of selected wavelengths to 47-44% for simeprevir and daclatasvir, respectively offering a fast and sensitive technique for the determination of simeprevir and daclatasvir. Validation results underscore the models' effectiveness, as evidenced by recovery rates close to 100% with relative root mean square error of prediction (RRMSEP) of 2.253 and 2.1381 for simeprevir and daclatasvir, respectively. Moreover, the proposed models have been applied to determine the pharmacokinetics of simeprevir and daclatasvir, providing valuable insights into their distribution and elimination patterns. Overall, the study demonstrates the effectiveness of synchronous spectrofluorimetry coupled with multivariate calibration optimized by firefly algorithms in accurately determining and quantifying simeprevir and daclatasvir in HCV antiviral treatment, offering potential applications in pharmaceutical formulation analysis and pharmacokinetic studies for these drugs.
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Affiliation(s)
- Ahmed Serag
- Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Al-Azhar University, 11751 Nasr City, Cairo, Egypt.
| | - Reem M Alnemari
- Department of Pharmaceutics and Pharmaceutical Technology, College of Pharmacy, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
| | - Maram H Abduljabbar
- Department of Pharmacology and Toxicology, College of Pharmacy, Taif University, P.O. Box 11099, 21944 Taif, Saudi Arabia
| | - Manal E Alosaimi
- Department of Basic Sciences, College of Medicine, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia
| | - Atiah H Almalki
- Department of Pharmaceutical Chemistry, College of Pharmacy, Taif University, P.O. Box 11099, 21944 Taif, Saudi Arabia; Addiction and Neuroscience Research Unit, Health Science Campus, Taif University, P.O. Box 11099, 21944 Taif, Saudi Arabia
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2
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Sagan SM, Weber SC. Let's phase it: viruses are master architects of biomolecular condensates. Trends Biochem Sci 2023; 48:229-243. [PMID: 36272892 DOI: 10.1016/j.tibs.2022.09.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 11/15/2022]
Abstract
Viruses compartmentalize their replication and assembly machinery to both evade detection and concentrate the viral proteins and nucleic acids necessary for genome replication and virion production. Accumulating evidence suggests that diverse RNA and DNA viruses form replication organelles and nucleocapsid assembly sites using phase separation. In general, the biogenesis of these compartments is regulated by two types of viral protein, collectively known as antiterminators and nucleocapsid proteins, respectively. Herein, we discuss how RNA viruses establish replication organelles and nucleocapsid assembly sites, and the evidence that these compartments form through phase separation. While this review focuses on RNA viruses, accumulating evidence suggests that all viruses rely on phase separation and form biomolecular condensates important for completing the infectious cycle.
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Affiliation(s)
- Selena M Sagan
- Department of Microbiology & Immunology, McGill University, Montreal, QC, Canada; Department of Biochemistry, McGill University, Montreal, QC, Canada.
| | - Stephanie C Weber
- Department of Biology, McGill University, Montreal, QC, Canada; Department of Physics, McGill University, Montreal, QC, Canada
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Studies of the symmetric binding mode of daclatasvir and analogs using a new homology model of HCV NS5A GT-4a. J Mol Model 2023; 29:25. [PMID: 36580076 PMCID: PMC9800351 DOI: 10.1007/s00894-022-05420-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/14/2022] [Indexed: 12/30/2022]
Abstract
CONTEXT Egypt has a high prevalence of the hepatitis C virus (HCV) genotype 4a (GT-4a). Unfortunately, the high resistance it exhibited still was not given the deserved attention in the scientific community. There is currently no consensus on the NS5A binding site because the crystal structure of HCV NS5A has not been resolved. The prediction of the binding modes of direct-acting antivirals (DAA) with the NS5A is a point of controversy due to the fact that several research groups presented different interaction models to elucidate the NS5A binding site. Consequently, a 3D model of HCV NS5A GT-4a was constructed and evaluated using molecular dynamics (MD) simulations. The generated model implies an intriguing new orientation of the AH relative to domain I. Additionally, the probable binding modes of marketed NS5A inhibitors were explored. MD simulations validated the stability of the predicted protein-ligand complexes. The suggested model predicts that daclatasvir and similar drugs bind symmetrically to HCV NS5A GT-4a. This will allow for the development of new NS5A-directed drugs, which may result in reduced resistance and/or a wider range of effectiveness against HCV. METHODS The 3D model of HCV NS5A GT-4a was constructed using the comparative modeling approach of the web-based application Robetta. Its stability was tested with 200-ns MD simulations using the Desmond package of Schrodinger. The OPLS2005 force field was assigned for minimization, and the RMSD, RMSF, and rGyr were tracked throughout the MD simulations. Fpocket was used to identify druggable protein pockets (cavities) over the simulation trajectories. The binding modes of marketed NS5A inhibitors were then generated and refined with the aid of docking predictions made by FRED and AutoDock Vina. The stability of these drugs in complex with GT-4a was investigated by using energetic and structural analyses over MD simulations. The Prime MM-GBSA (molecular mechanics/generalized Born surface area) method was used as a validation tool after the docking stage and for the averaged clusters after the MD simulation stage. We utilized PyMOL and VMD to visualize the data.
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Neufeldt CJ, Cortese M. Membrane architects: how positive-strand RNA viruses restructure the cell. J Gen Virol 2022; 103. [PMID: 35976091 DOI: 10.1099/jgv.0.001773] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Virus infection is a process that requires combined contributions from both virus and host factors. For this process to be efficient within the crowded host environment, viruses have evolved ways to manipulate and reorganize host structures to produce cellular microenvironments. Positive-strand RNA virus replication and assembly occurs in association with cytoplasmic membranes, causing a reorganization of these membranes to create microenvironments that support viral processes. Similarities between virus-induced membrane domains and cellular organelles have led to the description of these structures as virus replication organelles (vRO). Electron microscopy analysis of vROs in positive-strand RNA virus infected cells has revealed surprising morphological similarities between genetically diverse virus species. For all positive-strand RNA viruses, vROs can be categorized into two groups: those that make invaginations into the cellular membranes (In-vRO), and those that cause the production of protrusions from cellular membranes (Pr-vRO), most often in the form of double membrane vesicles (DMVs). In this review, we will discuss the current knowledge on the structure and biogenesis of these two different vRO classes as well as comparing morphology and function of vROs between various positive-strand RNA viruses. Finally, we will discuss recent studies describing pharmaceutical intervention in vRO formation as an avenue to control virus infection.
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Affiliation(s)
- Christopher John Neufeldt
- Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Mirko Cortese
- Telethon Institute of Genetics and Medicine, Pozzuoli, Italy
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5
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Hamdy J, Emadeldin N, Hamed MM, Frakolaki E, Katsamakas S, Vassilaki N, Zoidis G, Hirsch AKH, Abdel-Halim M, Abadi AH. Design and Synthesis of Novel Bis-Imidazolyl Phenyl Butadiyne Derivatives as HCV NS5A Inhibitors. Pharmaceuticals (Basel) 2022; 15:632. [PMID: 35631457 PMCID: PMC9146377 DOI: 10.3390/ph15050632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 05/08/2022] [Accepted: 05/12/2022] [Indexed: 11/17/2022] Open
Abstract
In today’s global plan to completely eradicate hepatitis C virus (HCV), the essential list of medications used for HCV treatment are direct-acting antivirals (DAAs), as interferon-sparing regimens have become the standard-of-care (SOC) treatment. HCV nonstructural protein 5A (NS5A) inhibitors are a very common component of these regimens. Food and Drug Administration (FDA)-approved NS5A inhibitors, although very potent, do not have the same potency against all eight genotypes of HCV. Therefore, this study aims to synthesize NS5A inhibitor analogues with high potency pan-genotypic activity and high metabolic stability. Starting from an NS5A inhibitor scaffold previously identified by our research group, we made several modifications. Two series of compounds were created to test the effect of changing the length and spatial conformation (para-para vs. meta-meta-positioned bis-imidazole-proline-carbamate), replacing amide groups in the linker with imidazole groups, as well as different end-cap compositions and sizes. The frontrunner inhibits genotype 1b (Con1) replicon, with an EC50 value in the picomolar range, and showed high genotypic coverage with nanomolar range EC50 values against four more genotypes. This together with its high metabolic stability (t½ > 120 min) makes it a potential preclinical candidate.
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Affiliation(s)
- Jehad Hamdy
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt; (J.H.); (N.E.)
| | - Nouran Emadeldin
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt; (J.H.); (N.E.)
| | - Mostafa M. Hamed
- Drug Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)—Helmholtz Centre for Infection Research (HZI), Campus E8.1, 66123 Saarbrücken, Germany; (M.M.H.); (A.K.H.H.)
| | - Efseveia Frakolaki
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Vas. Sofias Avenue, 11521 Athens, Greece; (E.F.); (N.V.)
| | - Sotirios Katsamakas
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, 15771 Athens, Greece;
| | - Niki Vassilaki
- Molecular Virology Laboratory, Department of Microbiology, Hellenic Pasteur Institute, Vas. Sofias Avenue, 11521 Athens, Greece; (E.F.); (N.V.)
| | - Grigoris Zoidis
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, 15771 Athens, Greece;
| | - Anna K. H. Hirsch
- Drug Design and Optimization, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)—Helmholtz Centre for Infection Research (HZI), Campus E8.1, 66123 Saarbrücken, Germany; (M.M.H.); (A.K.H.H.)
- Department of Pharmacy, Saarland University, Campus E8.1, 66123 Saarbrücken, Germany
| | - Mohammad Abdel-Halim
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt; (J.H.); (N.E.)
| | - Ashraf H. Abadi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo 11835, Egypt; (J.H.); (N.E.)
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6
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Abdallah M, Hamed MM, Frakolaki E, Katsamakas S, Vassilaki N, Bartenschlager R, Zoidis G, Hirsch AKH, Abdel-Halim M, Abadi AH. Redesigning of the cap conformation and symmetry of the diphenylethyne core to yield highly potent pan-genotypic NS5A inhibitors with high potency and high resistance barrier. Eur J Med Chem 2021; 229:114034. [PMID: 34959173 DOI: 10.1016/j.ejmech.2021.114034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/28/2021] [Accepted: 11/29/2021] [Indexed: 11/15/2022]
Abstract
Herein, we report the discovery of several NS5A inhibitors with potency against HCV genotype 1b in the picomolar range. Compounds (15, 33) were of extremely high potency against HCV genotype 1b (EC50 ≈ 1 pM), improved activity against genotype 3a (GT 3a) and good metabolic stability. We studied the impact of changing the cap conformation relative to the diphenylethyne core and/or compound symmetry on both potency and metabolic stability. The analogs obtained exhibited improved potency against HCV genotypes 1a, 1b, 3a and 4a compared to the clinically approved candidate daclatasvir with EC50 values in the low picomolar range and SI50s > 7 orders of magnitude. Compound 15, a symmetrically m-, m'-substituted diphenyl ethyne analog, was 150-fold more potent than daclatasvir against GT 3a, while compound 33, an asymmetrically m-, p-substituted diphenyl ethyne analog, was 35-fold more potent than daclatasvir against GT 3a. In addition, compound 15 exhibited a higher resistance barrier than daclatasvir against genotype 1b.
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Affiliation(s)
- Mennatallah Abdallah
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo, 11835, Egypt
| | - Mostafa M Hamed
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University Campus E8.1, 66123, Saarbrücken, Germany
| | - Efseveia Frakolaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Vas. Sofias Avenue, 11521, Athens, Greece
| | - Sotirios Katsamakas
- School of Health Sciences, Department of Pharmacy, Division of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, GR-15771, Athens, Greece
| | - Niki Vassilaki
- Molecular Virology Laboratory, Hellenic Pasteur Institute, Vas. Sofias Avenue, 11521, Athens, Greece
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany; German Center for Infection Research, Heidelberg Partner Site, Germany
| | - Grigoris Zoidis
- School of Health Sciences, Department of Pharmacy, Division of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, GR-15771, Athens, Greece.
| | - Anna K H Hirsch
- Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University Campus E8.1, 66123, Saarbrücken, Germany; Department of Pharmacy, Saarland University, Campus E8.1, Saarbrücken, 66123, Germany
| | - Mohammad Abdel-Halim
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo, 11835, Egypt.
| | - Ashraf H Abadi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Cairo, 11835, Egypt.
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7
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Twu WI, Lee JY, Kim H, Prasad V, Cerikan B, Haselmann U, Tabata K, Bartenschlager R. Contribution of autophagy machinery factors to HCV and SARS-CoV-2 replication organelle formation. Cell Rep 2021; 37:110049. [PMID: 34788596 PMCID: PMC8577994 DOI: 10.1016/j.celrep.2021.110049] [Citation(s) in RCA: 60] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/02/2021] [Accepted: 11/02/2021] [Indexed: 02/09/2023] Open
Abstract
Positive-strand RNA viruses replicate in close association with rearranged intracellular membranes. For hepatitis C virus (HCV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), these rearrangements comprise endoplasmic reticulum (ER)-derived double membrane vesicles (DMVs) serving as RNA replication sites. Cellular factors involved in DMV biogenesis are poorly defined. Here, we show that despite structural similarity of viral DMVs with autophagosomes, conventional macroautophagy is dispensable for HCV and SARS-CoV-2 replication. However, both viruses exploit factors involved in autophagosome formation, most notably class III phosphatidylinositol 3-kinase (PI3K). As revealed with a biosensor, PI3K is activated in cells infected with either virus to produce phosphatidylinositol 3-phosphate (PI3P) while kinase complex inhibition or depletion profoundly reduces replication and viral DMV formation. The PI3P-binding protein DFCP1, recruited to omegasomes in early steps of autophagosome formation, participates in replication and DMV formation of both viruses. These results indicate that phylogenetically unrelated HCV and SARS-CoV-2 exploit similar components of the autophagy machinery to create their replication organelles.
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Affiliation(s)
- Woan-Ing Twu
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ji-Young Lee
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Heeyoung Kim
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany; Center for Infection Research (DZIF), Partner Site Heidelberg, 69120 Heidelberg, Germany
| | - Vibhu Prasad
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Berati Cerikan
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Uta Haselmann
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany; Center for Infection Research (DZIF), Partner Site Heidelberg, 69120 Heidelberg, Germany
| | - Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany; Center for Infection Research (DZIF), Partner Site Heidelberg, 69120 Heidelberg, Germany; Division Virus-Associated Carcinogenesis, German Cancer Research Center, 69120 Heidelberg, Germany.
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8
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Chhajer H, Rizvi VA, Roy R. Life cycle process dependencies of positive-sense RNA viruses suggest strategies for inhibiting productive cellular infection. J R Soc Interface 2021; 18:20210401. [PMID: 34753308 PMCID: PMC8580453 DOI: 10.1098/rsif.2021.0401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/18/2021] [Indexed: 12/25/2022] Open
Abstract
Life cycle processes of positive-strand (+)RNA viruses are broadly conserved across families, yet they employ different strategies to grow in the cell. Using a generalized dynamical model for intracellular (+)RNA virus growth, we decipher these life cycle determinants and their dependencies for several viruses and parse the effects of viral mutations, drugs and host cell permissivity. We show that poliovirus employs rapid replication and virus assembly, whereas the Japanese encephalitis virus leverages its higher rate of translation and efficient cellular reorganization compared to the hepatitis C virus. Stochastic simulations demonstrate infection extinction if all seeding (inoculating) viral RNA degrade before establishing robust replication critical for infection. The probability of this productive cellular infection, 'cellular infectivity', is affected by virus-host processes and defined by early life cycle events and viral seeding. An increase in cytoplasmic RNA degradation and delay in vesicular compartment formation reduces infectivity, more so when combined. Synergy among these parameters in limiting (+)RNA virus infection as predicted by our model suggests new avenues for inhibiting infections by targeting the early life cycle bottlenecks.
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Affiliation(s)
- Harsh Chhajer
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Vaseef A. Rizvi
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, Karnataka, India
| | - Rahul Roy
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore 560012, Karnataka, India
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, Karnataka, India
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9
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The Compound SBI-0090799 Inhibits Zika Virus Infection by Blocking De Novo Formation of the Membranous Replication Compartment. J Virol 2021; 95:e0099621. [PMID: 34468177 DOI: 10.1128/jvi.00996-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Zika virus (ZIKV) is a mosquito-borne pathogen classified by the World Health Organization (WHO) as a public health emergency of international concern in 2016, and it is still identified as a priority disease. Although most infected individuals are asymptomatic or show mild symptoms, a risk of neurologic complications is associated with infection in adults. Additionally, infection during pregnancy is directly linked to microcephaly and other congenital malformations. Since there are no currently available vaccines or approved therapeutics for this virus, there is a critical unmet need in developing treatments to prevent future ZIKV outbreaks. Toward this end, we performed a large-scale cell-based high-content screen of 51,520 chemical compounds to identify potential antiviral drug candidates. The compound (2E)-N-benzyl-3-(4-butoxyphenyl)prop-2-enamide (SBI-0090799) was found to inhibit replication of multiple ZIKV strains and in different cell systems. SBI-0090799 did not affect viral entry or RNA translation but suppressed RNA replication by preventing the formation of the membranous replication compartment. Selection of drug-resistant viruses identified single-amino-acid substitutions in the N-terminal region of nonstructural protein NS4A, arguing this is the likely drug target. These resistance mutations rescued viral RNA replication and restored the formation of the membranous replication compartment. This mechanism of action is similar to clinically approved NS5A inhibitors for hepatitis C virus (HCV). Taken together, SBI-0090799 represents a promising lead candidate for the development of an antiviral treatment against ZIKV infection for the mitigation of severe complications and potential resurgent outbreaks of the virus. IMPORTANCE This study describes the elucidation of (2E)-N-benzyl-3-(4-butoxyphenyl)prop-2-enamide (SBI-0090799) as a selective and potent inhibitor of Zika virus (ZIKV) replication using a high-throughput screening approach. Mapping and resistance studies, supported by electron microscopy observations, indicate that the small molecule is functioning through inhibition of NS4A-mediated formation of ZIKV replication compartments in the endoplasmic reticulum (ER). Intriguingly, this defines a novel nonenzymatic target and chemical matter for the development of a new class of ZIKV antivirals. Moreover, chemical modulation affecting this nonstructural protein mirrors the identification and development of hepatitis C virus (HCV) NS5A inhibitor daclatasvir and its derivatives, similarly interfering with the formation of the viral replication compartment and also targeting a protein with no enzymatic activity, which have been part of a curative strategy for HCV.
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10
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Abstract
Alphaviruses are positive-strand RNA viruses, typically transmitted by mosquitoes between vertebrate hosts. They encode four essential replication proteins, the non-structural proteins nsP1-4, which possess the enzymatic activities of RNA capping, RNA helicase, site-specific protease, ADP-ribosyl removal and RNA polymerase. Alphaviruses have been key models in the study of membrane-associated RNA replication, which is a conserved feature among the positive-strand RNA viruses of animals and plants. We review new structural and functional information on the nsPs and their interaction with host proteins and membranes, as well as with viral RNA sequences. The dodecameric ring structure of nsP1 is likely to be one of the evolutionary innovations that facilitated the success of the progenitors of current positive-strand RNA viruses.
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Affiliation(s)
- Tero Ahola
- Department of Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
| | - Gerald McInerney
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Andres Merits
- Institute of Technology, University of Tartu, Tartu, Estonia.
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11
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Bobardt M, Ramirez CM, Baum MM, Ure D, Foster R, Gallay PA. The combination of the NS5A and cyclophilin inhibitors results in an additive anti-HCV inhibition in humanized mice without development of resistance. PLoS One 2021; 16:e0251934. [PMID: 34014993 PMCID: PMC8136729 DOI: 10.1371/journal.pone.0251934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
We and others previously reported that the direct-acting agents (DAA) NS5A inhibitors (NS5Ai) and the host-targeting agents cyclophilin inhibitors (CypIs) inhibit HCV replication in vitro. In this study, we investigated whether the combination of NS5Ai and CypI offers a potent anti-HCV effect in vivo. A single administration of NS5Ai or CypI alone to HCV-infected humanized-mice inhibits HCV replication. The combination of NS5Ai with CypI suppresses HCV (GT1a, GT2a, GT3a and GT4a) replication in an additive manner. NS5Ai/CypI combinations provide a statistically more profound anti-HCV inhibition for GT2a and GT3a than GT1a and GT4a, leading to a fastest and deepest inhibition of GT2a and GT3a replications. Combining CypI with NS5Ai prevents the viral rebound normally observed in mice treated with NS5Ai alone. Results were confirmed in mice implanted with human hepatocytes from different donors. Therefore, the combination of NS5Ai with CypI may serve as a regimen for the treatment of HCV patients with specific genotypes and disorder conditions, which diminish sustain viral response levels to DAA, such as GT3a infection, cirrhosis, and DAA resistance associated with the selection of resistance-associated substitutions present at baseline or are acquired during treatment.
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Affiliation(s)
- Michael Bobardt
- Department of Immunology & Microbiology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Christina M. Ramirez
- Los Angeles (UCLA) Fielding School of Public Health, University of California, Center for Health Sciences, Los Angeles, CA, United States of America
| | - Marc M. Baum
- Department of Chemistry, Oak Crest Institute of Science, Monrovia, CA, United States of America
| | - Daren Ure
- Hepion Pharmaceuticals, Edison, New Jersey
| | | | - Philippe A. Gallay
- Department of Immunology & Microbiology, The Scripps Research Institute, La Jolla, California, United States of America
- * E-mail:
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12
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Zhang Y, Chen S, Yuan Z, Yi Z. Bioorthogonal dissection of the replicase assembly of hepatitis C virus. Cell Chem Biol 2021; 28:1366-1378.e4. [PMID: 33798447 PMCID: PMC8444619 DOI: 10.1016/j.chembiol.2021.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/21/2021] [Accepted: 03/10/2021] [Indexed: 01/01/2023]
Abstract
Positive-strand RNA viruses such as hepatitis C virus (HCV), flaviviruses, and coronaviruses are medically important. Assembly of replicase on host membranes is a conserved replication strategy and an attractive antiviral target. The mechanisms of replicase assembly are largely unknown, due to the technical difficulties in purifying the replicase and carrying out structural studies. Here, with an HCV replicase assembly surrogate system, we employed a bioorthogonal system to introduce the photolabile unnatural amino into each residue in the cytosolic regions of NS4B and the amphipathic helix (AH) of NS5A. Photocrosslinking enabled visualization of NS4B oligomerization and NS5A dimerization at pinpointed interacting residues and identifying contacting sites among the replicase components. Characterization of the interacting sites revealed hub elements in replicase assembly by docking replicase components to prompt protein-protein interactions. The results provide information about the molecular architecture of the replicase, advancing understanding of the mechanism of replicase assembly.
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Affiliation(s)
- Yang Zhang
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Shuiye Chen
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China
| | - Zhenghong Yuan
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China.
| | - Zhigang Yi
- Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai 200032, China; Shanghai Public Health Clinical Center, Fudan University, Shanghai 201052, China.
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13
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Li HC, Yang CH, Lo SY. Hepatitis C Viral Replication Complex. Viruses 2021; 13:v13030520. [PMID: 33809897 PMCID: PMC8004249 DOI: 10.3390/v13030520] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 12/16/2022] Open
Abstract
The life cycle of the hepatitis C virus (HCV) can be divided into several stages, including viral entry, protein translation, RNA replication, viral assembly, and release. HCV genomic RNA replication occurs in the replication organelles (RO) and is tightly linked to ER membrane alterations containing replication complexes (proteins NS3 to NS5B). The amplification of HCV genomic RNA could be regulated by the RO biogenesis, the viral RNA structure (i.e., cis-acting replication elements), and both viral and cellular proteins. Studies on HCV replication have led to the development of direct-acting antivirals (DAAs) targeting the replication complex. This review article summarizes the viral and cellular factors involved in regulating HCV genomic RNA replication and the DAAs that inhibit HCV replication.
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Affiliation(s)
- Hui-Chun Li
- Department of Biochemistry, Tzu Chi University, Hualien 97004, Taiwan;
| | - Chee-Hing Yang
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 97004, Taiwan;
| | - Shih-Yen Lo
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien 97004, Taiwan;
- Department of Laboratory Medicine, Buddhist Tzu Chi General Hospital, Hualien 97004, Taiwan
- Correspondence: ; Tel.: +886-3-8565301 (ext. 2322)
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14
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Jirasko V, Lends A, Lakomek N, Fogeron M, Weber ME, Malär AA, Penzel S, Bartenschlager R, Meier BH, Böckmann A. Dimer Organization of Membrane‐Associated NS5A of Hepatitis C Virus as Determined by Highly Sensitive
1
H‐Detected Solid‐State NMR. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013296] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Alons Lends
- Physical Chemistry ETH Zurich 8093 Zurich Switzerland
| | | | - Marie‐Laure Fogeron
- Molecular Microbiology and Structural Biochemistry Labex Ecofect UMR 5086 CNRS Université de Lyon 1 7 passage du Vercors 69367 Lyon France
| | | | | | | | - Ralf Bartenschlager
- Department of Infectious Diseases Molecular Virology Heidelberg University Im Neuenheimer Feld 345 69120 Heidelberg Germany
- German Centre for Infection Research (DZIF) Heidelberg partner site Heidelberg Germany
| | - Beat H. Meier
- Physical Chemistry ETH Zurich 8093 Zurich Switzerland
| | - Anja Böckmann
- Molecular Microbiology and Structural Biochemistry Labex Ecofect UMR 5086 CNRS Université de Lyon 1 7 passage du Vercors 69367 Lyon France
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15
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Jirasko V, Lends A, Lakomek N, Fogeron M, Weber ME, Malär AA, Penzel S, Bartenschlager R, Meier BH, Böckmann A. Dimer Organization of Membrane-Associated NS5A of Hepatitis C Virus as Determined by Highly Sensitive 1 H-Detected Solid-State NMR. Angew Chem Int Ed Engl 2021; 60:5339-5347. [PMID: 33205864 PMCID: PMC7986703 DOI: 10.1002/anie.202013296] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/17/2020] [Indexed: 12/17/2022]
Abstract
The Hepatitis C virus nonstructural protein 5A (NS5A) is a membrane-associated protein involved in multiple steps of the viral life cycle. Direct-acting antivirals (DAAs) targeting NS5A are a cornerstone of antiviral therapy, but the mode-of-action of these drugs is poorly understood. This is due to the lack of information on the membrane-bound NS5A structure. Herein, we present the structural model of an NS5A AH-linker-D1 protein reconstituted as proteoliposomes. We use highly sensitive proton-detected solid-state NMR methods suitable to study samples generated through synthetic biology approaches. Spectra analyses disclose that both the AH membrane anchor and the linker are highly flexible. Paramagnetic relaxation enhancements (PRE) reveal that the dimer organization in lipids requires a new type of NS5A self-interaction not reflected in previous crystal structures. In conclusion, we provide the first characterization of NS5A AH-linker-D1 in a lipidic environment shedding light onto the mode-of-action of clinically used NS5A inhibitors.
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Affiliation(s)
| | - Alons Lends
- Physical ChemistryETH Zurich8093ZurichSwitzerland
| | | | - Marie‐Laure Fogeron
- Molecular Microbiology and Structural BiochemistryLabex EcofectUMR 5086 CNRSUniversité de Lyon 17 passage du Vercors69367LyonFrance
| | | | | | | | - Ralf Bartenschlager
- Department of Infectious DiseasesMolecular VirologyHeidelberg UniversityIm Neuenheimer Feld 34569120HeidelbergGermany
- German Centre for Infection Research (DZIF)Heidelberg partner siteHeidelbergGermany
| | | | - Anja Böckmann
- Molecular Microbiology and Structural BiochemistryLabex EcofectUMR 5086 CNRSUniversité de Lyon 17 passage du Vercors69367LyonFrance
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16
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Anton A, Mazeaud C, Freppel W, Gilbert C, Tremblay N, Sow AA, Roy M, Rodrigue-Gervais IG, Chatel-Chaix L. Valosin-containing protein ATPase activity regulates the morphogenesis of Zika virus replication organelles and virus-induced cell death. Cell Microbiol 2021; 23:e13302. [PMID: 33432690 DOI: 10.1111/cmi.13302] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 12/01/2020] [Accepted: 12/15/2020] [Indexed: 12/31/2022]
Abstract
With no available therapies, infections with Zika virus (ZIKV) constitute a major public health concern as they can lead to congenital microcephaly. In order to generate an intracellular environment favourable to viral replication, ZIKV induces endomembrane remodelling and the morphogenesis of replication factories via enigmatic mechanisms. In this study, we identified the AAA+ type ATPase valosin-containing protein (VCP) as a cellular interaction partner of ZIKV non-structural protein 4B (NS4B). Importantly, its pharmacological inhibition as well as the expression of a VCP dominant-negative mutant impaired ZIKV replication. In infected cells, VCP is relocalised to large ultrastructures containing both NS4B and NS3, which are reminiscent of dengue virus convoluted membranes. Moreover, short treatment with the VCP inhibitors NMS-873 or CB-5083 drastically decreased the abundance and size of ZIKV-induced convoluted membranes. Furthermore, NMS-873 treatment inhibited ZIKV-induced mitochondria elongation previously reported to be physically and functionally linked to convoluted membranes in case of the closely related dengue virus. Finally, VCP inhibition resulted in enhanced apoptosis of ZIKV-infected cells strongly suggesting that convoluted membranes limit virus-induced cytopathic effects. Altogether, this study identifies VCP as a host factor required for ZIKV life cycle and more precisely, for the maintenance of viral replication factories. Our data further support a model in which convoluted membranes regulate ZIKV life cycle by impacting on mitochondrial functions and ZIKV-induced death signals in order to create a cytoplasmic environment favourable to viral replication.
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Affiliation(s)
- Anaïs Anton
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Clément Mazeaud
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Wesley Freppel
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Claudia Gilbert
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Nicolas Tremblay
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Aïssatou Aïcha Sow
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Marie Roy
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Ian Gaël Rodrigue-Gervais
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada
| | - Laurent Chatel-Chaix
- Centre Armand-Frappier Santé Biotechnologie, Institut National de la Recherche Scientifique, Laval, Québec, Canada.,Center of Excellence in Research on Orphan Diseases-Courtois Foundation (CERMO-FC), Montreal, Québec, Canada.,Réseau Intersectoriel de Recherche en Santé de l'Université du Québec (RISUQ), Québec, Canada
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17
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Alzahrani N, Wu MJ, Shanmugam S, Yi M. Delayed by Design: Role of Suboptimal Signal Peptidase Processing of Viral Structural Protein Precursors in Flaviviridae Virus Assembly. Viruses 2020; 12:v12101090. [PMID: 32993149 PMCID: PMC7601889 DOI: 10.3390/v12101090] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/04/2020] [Accepted: 09/24/2020] [Indexed: 02/06/2023] Open
Abstract
The Flaviviridae virus family is classified into four different genera, including flavivirus, hepacivirus, pegivirus, and pestivirus, which cause significant morbidity and mortality in humans and other mammals, including ruminants and pigs. These are enveloped, single-stranded RNA viruses sharing a similar genome organization and replication scheme with certain unique features that differentiate them. All viruses in this family express a single polyprotein that encodes structural and nonstructural proteins at the N- and C-terminal regions, respectively. In general, the host signal peptidase cleaves the structural protein junction sites, while virus-encoded proteases process the nonstructural polyprotein region. It is known that signal peptidase processing is a rapid, co-translational event. Interestingly, certain signal peptidase processing site(s) in different Flaviviridae viral structural protein precursors display suboptimal cleavage kinetics. This review focuses on the recent progress regarding the Flaviviridae virus genus-specific mechanisms to downregulate signal peptidase-mediated processing at particular viral polyprotein junction sites and the role of delayed processing at these sites in infectious virus particle assembly.
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18
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A Small Molecule, 4-Phenylbutyric Acid, Suppresses HCV Replication via Epigenetically Induced Hepatic Hepcidin. Int J Mol Sci 2020; 21:ijms21155516. [PMID: 32752233 PMCID: PMC7432483 DOI: 10.3390/ijms21155516] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 07/30/2020] [Accepted: 07/30/2020] [Indexed: 01/02/2023] Open
Abstract
Hepatic hepcidin is a well-known major iron regulator and has been reported to be closely related to hepatitis C virus (HCV) replication. However, pharmacological targeting of the hepcidin in HCV replication has not been reported. A short-chain fatty acid, 4-Phenyl butyrate (4-PBA), is an acid chemical chaperone that acts as a histone deacetylase inhibitor (HDACi) to promote chromosomal histone acetylation. Here, we investigated the therapeutic effect of 4-PBA on hepcidin expression and HCV replication. We used HCV genotype 1b Huh 7.5-Con1 replicon cells and engraftment of NOD/SCID mice as in vitro and in vivo models to test the effect of 4-PBA. It was found that 4-PBA inhibited HCV replication in Huh7.5-Con1 replicon cells in a concentration- and time-dependent manner through the induction of hepcidin expression by epigenetic modification and subsequent upregulation of interferon-α signaling. HCV formed a membranous web composed of double-membrane vesicles and was utilized for RNA replication. Moreover, 4-PBA also disrupted the integrity of the membranous web and interfered with the molecular interactions critical for the assembly of the HCV replication complex. These findings suggest that 4-PBA is a key epigenetic inducer of anti-HCV hepatic hepcidin and might at least in part play a role in targeting host factors related to HCV infection as an attractive complement to current HCV therapies.
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19
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Cerikan B, Goellner S, Neufeldt CJ, Haselmann U, Mulder K, Chatel-Chaix L, Cortese M, Bartenschlager R. A Non-Replicative Role of the 3' Terminal Sequence of the Dengue Virus Genome in Membranous Replication Organelle Formation. Cell Rep 2020; 32:107859. [PMID: 32640225 PMCID: PMC7351112 DOI: 10.1016/j.celrep.2020.107859] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 04/11/2020] [Accepted: 06/12/2020] [Indexed: 12/14/2022] Open
Abstract
Dengue virus (DENV) and Zika virus (ZIKV), members of the Flavivirus genus, rearrange endoplasmic reticulum membranes to induce invaginations known as vesicle packets (VPs), which are the assumed sites for viral RNA replication. Mechanistic information on VP biogenesis has so far been difficult to attain due to the necessity of studying their formation under conditions of viral replication, where perturbations reducing replication will inevitably impact VP formation. Here, we report a replication-independent expression system, designated pIRO (plasmid-induced replication organelle formation) that induces bona fide DENV and ZIKV VPs that are morphologically indistinguishable from those in infected cells. Using this system, we demonstrate that sequences in the 3' terminal RNA region of the DENV, but not the ZIKV genome, contribute to VP formation in a non-replicative manner. These results validate the pIRO system that opens avenues for mechanistically dissecting virus replication from membrane reorganization.
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Affiliation(s)
- Berati Cerikan
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Sarah Goellner
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Christopher John Neufeldt
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Uta Haselmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Klaas Mulder
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Laurent Chatel-Chaix
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, University, 69120 Heidelberg, Germany.
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20
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Colpitts CC, Ridewood S, Schneiderman B, Warne J, Tabata K, Ng CF, Bartenschlager R, Selwood DL, Towers GJ. Hepatitis C virus exploits cyclophilin A to evade PKR. eLife 2020; 9:e52237. [PMID: 32539931 PMCID: PMC7297535 DOI: 10.7554/elife.52237] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 05/28/2020] [Indexed: 12/12/2022] Open
Abstract
Counteracting innate immunity is essential for successful viral replication. Host cyclophilins (Cyps) have been implicated in viral evasion of host antiviral responses, although the mechanisms are still unclear. Here, we show that hepatitis C virus (HCV) co-opts the host protein CypA to aid evasion of antiviral responses dependent on the effector protein kinase R (PKR). Pharmacological inhibition of CypA rescues PKR from antagonism by HCV NS5A, leading to activation of an interferon regulatory factor-1 (IRF1)-driven cell intrinsic antiviral program that inhibits viral replication. These findings further the understanding of the complexity of Cyp-virus interactions, provide mechanistic insight into the remarkably broad antiviral spectrum of Cyp inhibitors, and uncover novel aspects of PKR activity and regulation. Collectively, our study identifies a novel antiviral mechanism that harnesses cellular antiviral immunity to suppress viral replication.
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Affiliation(s)
- Che C Colpitts
- Department of Biomedical and Molecular Sciences, Queen’s UniversityKingstonCanada
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Sophie Ridewood
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Bethany Schneiderman
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Justin Warne
- Wolfson Institute for Biomedical Research, UCLLondonUnited Kingdom
| | - Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg UniversityHeidelbergGermany
| | - Caitlin F Ng
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg UniversityHeidelbergGermany
- Division Virus-Associated Carcinogenesis, German Cancer Research CenterHeidelbergGermany
- German Center for Infection Research (DZIF), Heidelberg Partner SiteHeidelbergGermany
| | - David L Selwood
- Department of Medicine, Imperial College LondonLondonUnited Kingdom
| | - Greg J Towers
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
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21
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Wolff G, Melia CE, Snijder EJ, Bárcena M. Double-Membrane Vesicles as Platforms for Viral Replication. Trends Microbiol 2020; 28:1022-1033. [PMID: 32536523 PMCID: PMC7289118 DOI: 10.1016/j.tim.2020.05.009] [Citation(s) in RCA: 188] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/09/2020] [Accepted: 05/14/2020] [Indexed: 12/12/2022]
Abstract
Viruses, as obligate intracellular parasites, exploit cellular pathways and resources in a variety of fascinating ways. A striking example of this is the remodelling of intracellular membranes into specialized structures that support the replication of positive-sense ssRNA (+RNA) viruses infecting eukaryotes. These distinct forms of virus-induced structures include double-membrane vesicles (DMVs), found during viral infections as diverse and notorious as those of coronaviruses, enteroviruses, noroviruses, or hepatitis C virus. Our understanding of these DMVs has evolved over the past 15 years thanks to advances in imaging techniques and modern molecular biology tools. In this article, we review contemporary understanding of the biogenesis, structure, and function of virus-induced DMVs as well as the open questions posed by these intriguing structures.
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Affiliation(s)
- Georg Wolff
- Section Electron Microscopy, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Charlotte E Melia
- Section Electron Microscopy, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Eric J Snijder
- Molecular Virology laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Montserrat Bárcena
- Section Electron Microscopy, Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands.
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22
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Abstract
Viruses manipulate cellular lipids and membranes at each stage of their life cycle. This includes lipid-receptor interactions, the fusion of viral envelopes with cellular membranes during endocytosis, the reorganization of cellular membranes to form replication compartments, and the envelopment and egress of virions. In addition to the physical interactions with cellular membranes, viruses have evolved to manipulate lipid signaling and metabolism to benefit their replication. This review summarizes the strategies that viruses use to manipulate lipids and membranes at each stage in the viral life cycle.
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Affiliation(s)
- Ellen Ketter
- Department of Microbiology, The University of Chicago, Chicago, Illinois 60637, USA;
| | - Glenn Randall
- Department of Microbiology, The University of Chicago, Chicago, Illinois 60637, USA;
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23
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Dash S, Aydin Y, Widmer KE, Nayak L. Hepatocellular Carcinoma Mechanisms Associated with Chronic HCV Infection and the Impact of Direct-Acting Antiviral Treatment. J Hepatocell Carcinoma 2020; 7:45-76. [PMID: 32346535 PMCID: PMC7167284 DOI: 10.2147/jhc.s221187] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 03/06/2020] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) infection is the major risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). The mechanisms of HCC initiation, growth, and metastasis appear to be highly complex due to the decade-long interactions between the virus, immune system, and overlapping bystander effects of host metabolic liver disease. The lack of a readily accessible animal model system for HCV is a significant obstacle to understand the mechanisms of viral carcinogenesis. Traditionally, the primary prevention strategy of HCC has been to eliminate infection by antiviral therapy. The success of virus elimination by antiviral treatment is determined by the SVR when the HCV is no longer detectable in serum. Interferon-alpha (IFN-α) and its analogs, pegylated IFN-α (PEG-IFN-α) alone with ribavirin (RBV), have been the primary antiviral treatment of HCV for many years with a low cure rate. The cloning and sequencing of HCV have allowed the development of cell culture models, which accelerated antiviral drug discovery. It resulted in the selection of highly effective direct-acting antiviral (DAA)-based combination therapy that now offers incredible success in curing HCV infection in more than 95% of all patients, including those with cirrhosis. However, several emerging recent publications claim that patients who have liver cirrhosis at the time of DAAs treatment face the risk of HCC occurrence and recurrence after viral cure. This remains a substantial challenge while addressing the long-term benefit of antiviral medicine. The host-related mechanisms that drive the risk of HCC in the absence of the virus are unknown. This review describes the multifaceted mechanisms that create a tumorigenic environment during chronic HCV infection. In addition to the potential oncogenic programming that drives HCC after viral clearance by DAAs, the current status of a biomarker development for early prediction of cirrhosis regression and HCC detection post viral treatment is discussed. Since DAAs treatment does not provide full protection against reinfection or viral transmission to other individuals, the recent studies for a vaccine development are also reviewed.
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Affiliation(s)
- Srikanta Dash
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA.,Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA.,Department of Medicine, Division of Gastroenterology, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
| | - Yucel Aydin
- Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA
| | - Kyle E Widmer
- Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA
| | - Leela Nayak
- Southeast Louisiana Veterans Health Care System, New Orleans, LA 70119, USA
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24
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Kazmierski WM, Baskaran S, Walker JT, Miriyala N, Meesala R, Beesu M, Adjabeng G, Grimes RM, Hamatake R, Leivers MR, Crosby R, Xia B, Remlinger K. GSK2818713, a Novel Biphenylene Scaffold-Based Hepatitis C NS5A Replication Complex Inhibitor with Broad Genotype Coverage. J Med Chem 2020; 63:4155-4170. [PMID: 32202782 DOI: 10.1021/acs.jmedchem.9b02176] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Pan-genotype NS5A inhibitors underpin hugely successful hepatitis C virus (HCV) therapy. The discovery of GSK2818713 (13), a nonstructural protein 5A (NS5A) HCV inhibitor characterized by a significantly improved genotype coverage relative to first-generation NS5A inhibitor daclatasvir (DCV), is detailed herein. The SAR analysis revealed cooperative potency effects of the biphenylene, bicyclic pyrrolidine (Aoc), and methyl-threonine structural motifs. Relative to DCV, 13 improved activity against genotype 1a (gt1a) and gt1b NS5A variants as well as HCV chimeric replicons containing NS5A fragments from genotypes 2-6. Long-term treatment of subgenomic replicons with 13 potently and durably decreased HCV RNA levels for gt1a, gt2a, and gt3a. These properties, suitable pharmacokinetics, and the lack of cross-resistance resulted in the selection of 13 as a preclinical candidate.
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Affiliation(s)
- Wieslaw M Kazmierski
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Sam Baskaran
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Jill T Walker
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Nagaraju Miriyala
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Ramu Meesala
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Mallesh Beesu
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - George Adjabeng
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Richard M Grimes
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Robert Hamatake
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Martin R Leivers
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Renae Crosby
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
| | - Bing Xia
- GlaxoSmithKline, 200 Cambridge Park Drive, Cambridge, Massachusetts 02140, United States
| | - Katja Remlinger
- GlaxoSmithKline, 5 Moore Drive, Research Triangle Park, North Carolina 27709, United States
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25
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Tabata K, Neufeldt CJ, Bartenschlager R. Hepatitis C Virus Replication. Cold Spring Harb Perspect Med 2020; 10:cshperspect.a037093. [PMID: 31570388 DOI: 10.1101/cshperspect.a037093] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Replication and amplification of the viral genome is a key process for all viruses. For hepatitis C virus (HCV), a positive-strand RNA virus, amplification of the viral genome requires the synthesis of a negative-sense RNA template, which is in turn used for the production of new genomic RNA. This process is governed by numerous proteins, both host and viral, as well as distinct lipids and specific RNA elements within the positive- and negative-strand RNAs. Moreover, this process requires specific changes to host cell ultrastructure to create microenvironments conducive to viral replication. This review will focus on describing the processes and factors involved in facilitating or regulating HCV genome replication.
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Affiliation(s)
- Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Christopher J Neufeldt
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany.,Division of Virus-Associated Carcinogenesis, German Cancer Research Center, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg Partner Site, 69120 Heidelberg, Germany
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26
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Visualization of Positive and Negative Sense Viral RNA for Probing the Mechanism of Direct-Acting Antivirals against Hepatitis C Virus. Viruses 2019; 11:v11111039. [PMID: 31717338 PMCID: PMC6893808 DOI: 10.3390/v11111039] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/03/2019] [Accepted: 11/07/2019] [Indexed: 12/14/2022] Open
Abstract
RNA viruses are highly successful pathogens and are the causative agents for many important diseases. To fully understand the replication of these viruses it is necessary to address the roles of both positive-strand RNA ((+)RNA) and negative-strand RNA ((−)RNA), and their interplay with viral and host proteins. Here we used branched DNA (bDNA) fluorescence in situ hybridization (FISH) to stain both the abundant (+)RNA and the far less abundant (−)RNA in both hepatitis C virus (HCV)- and Zika virus-infected cells, and combined these analyses with visualization of viral proteins through confocal imaging. We were able to phenotypically examine HCV-infected cells in the presence of uninfected cells and revealed the effect of direct-acting antivirals on HCV (+)RNA, (−)RNA, and protein, within hours of commencing treatment. Herein, we demonstrate that bDNA FISH is a powerful tool for the study of RNA viruses that can provide insights into drug efficacy and mechanism of action.
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Lee JS, Tabata K, Twu WI, Rahman MS, Kim HS, Yu JB, Jee MH, Bartenschlager R, Jang SK. RACK1 mediates rewiring of intracellular networks induced by hepatitis C virus infection. PLoS Pathog 2019; 15:e1008021. [PMID: 31525236 PMCID: PMC6762199 DOI: 10.1371/journal.ppat.1008021] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 09/26/2019] [Accepted: 08/05/2019] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) is a positive-strand RNA virus replicating in a membranous replication organelle composed primarily of double-membrane vesicles (DMVs) having morphological resemblance to autophagosomes. To define the mechanism of DMV formation and the possible link to autophagy, we conducted a yeast two-hybrid screening revealing 32 cellular proteins potentially interacting with HCV proteins. Among these was the Receptor for Activated Protein C Kinase 1 (RACK1), a scaffolding protein involved in many cellular processes, including autophagy. Depletion of RACK1 strongly inhibits HCV RNA replication without affecting HCV internal ribosome entry site (IRES) activity. RACK1 is required for the rewiring of subcellular membranous structures and for the induction of autophagy. RACK1 binds to HCV nonstructural protein 5A (NS5A), which induces DMV formation. NS5A interacts with ATG14L in a RACK1 dependent manner, and with the ATG14L-Beclin1-Vps34-Vps15 complex that is required for autophagosome formation. Both RACK1 and ATG14L are required for HCV DMV formation and viral RNA replication. These results indicate that NS5A participates in the formation of the HCV replication organelle through interactions with RACK1 and ATG14L. All positive-strand RNA viruses replicate their genomes in distinct membrane-associated compartments designated replication organelles. The compartmentalization of viral replication machinery allows the enrichment and coordination of cellular and viral factors required for RNA replication and the evasion from innate host defense systems. Hepatitis C virus (HCV), a prototype member of the Flaviviridae family, rearranges intracellular membranes to construct replication organelles composed primarily of double-membrane vesicles (DMVs) which are morphologically similar to autophagosomes. Nonstructural protein 5A (NS5A), which is essential for HCV replication, induces DMV formation. Here, we report that NS5A triggers DMV formation through interactions with RACK1 and components of the vesicle nucleation complex acting at the early stage of autophagy. These results illustrate how a virus skews cellular machineries to utilize them for its replication by hijacking cellular proteins through protein-protein interactions. This research sheds light on the molecular basis of replication organelle formation by HCV and possibly other viruses employing organelles with DMV morphology.
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Affiliation(s)
- Jae Seung Lee
- Division of Integrative Bioscience & Biotechnology, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
| | - Keisuke Tabata
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Woan-Ing Twu
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
| | - Md Shafiqur Rahman
- Department of Life Sciences, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
| | - Hee Sun Kim
- Division of Integrative Bioscience & Biotechnology, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
| | - Jin Bae Yu
- Department of Life Sciences, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
| | - Min Hyeok Jee
- Department of Life Sciences, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Heidelberg, Germany
- Division Virus-Associated Carcinogenesis, German Cancer Research Center, Heidelberg, Germany
| | - Sung Key Jang
- Division of Integrative Bioscience & Biotechnology, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
- Department of Life Sciences, POSTECH Biotech Center, POSTECH, Nam-gu, Pohang-si, Gyeongsangbuk-do, Rep. of KOREA
- * E-mail:
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Sofia MJ. The Discovery and Development of Daclatasvir: An Inhibitor of the Hepatitis C Virus NS5A Replication Complex. ACTA ACUST UNITED AC 2019. [PMCID: PMC7122418 DOI: 10.1007/7355_2018_47] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Neufeldt CJ, Cortese M, Acosta EG, Bartenschlager R. Rewiring cellular networks by members of the Flaviviridae family. Nat Rev Microbiol 2019; 16:125-142. [PMID: 29430005 PMCID: PMC7097628 DOI: 10.1038/nrmicro.2017.170] [Citation(s) in RCA: 230] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Members of the Flaviviridae virus family comprise a large group of enveloped viruses with a single-strand RNA genome of positive polarity. Several genera belong to this family, including the Hepacivirus genus, of which hepatitis C virus (HCV) is the prototype member, and the Flavivirus genus, which contains both dengue virus and Zika virus. Viruses of these genera differ in many respects, such as the mode of transmission or the course of infection, which is either predominantly persistent in the case of HCV or acutely self-limiting in the case of flaviviruses. Although the fundamental replication strategy of Flaviviridae members is similar, during the past few years, important differences have been discovered, including the way in which these viruses exploit cellular resources to facilitate viral propagation. These differences might be responsible, at least in part, for the various biological properties of these viruses, thus offering the possibility to learn from comparisons. In this Review, we discuss the current understanding of how Flaviviridae viruses manipulate and usurp cellular pathways in infected cells. Specifically, we focus on comparing strategies employed by flaviviruses with those employed by hepaciviruses, and we discuss the importance of these interactions in the context of viral replication and antiviral therapies.
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Affiliation(s)
- Christopher J Neufeldt
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Eliana G Acosta
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg Partner Site, 69120 Heidelberg, Germany
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Sachse M, Fernández de Castro I, Tenorio R, Risco C. The viral replication organelles within cells studied by electron microscopy. Adv Virus Res 2019; 105:1-33. [PMID: 31522702 PMCID: PMC7112055 DOI: 10.1016/bs.aivir.2019.07.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Transmission electron microscopy (TEM) has been crucial to study viral infections. As a result of recent advances in light and electron microscopy, we are starting to be aware of the variety of structures that viruses assemble inside cells. Viruses often remodel cellular compartments to build their replication factories. Remarkably, viruses are also able to induce new membranes and new organelles. Here we revise the most relevant imaging technologies to study the biogenesis of viral replication organelles. Live cell microscopy, correlative light and electron microscopy, cryo-TEM, and three-dimensional imaging methods are unveiling how viruses manipulate cell organization. In particular, methods for molecular mapping in situ in two and three dimensions are revealing how macromolecular complexes build functional replication complexes inside infected cells. The combination of all these imaging approaches is uncovering the viral life cycle events with a detail never seen before.
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Affiliation(s)
- Martin Sachse
- Unité Technologie et service BioImagerie Ultrastructurale, Institut Pasteur, Paris, France.
| | | | - Raquel Tenorio
- Cell Structure Laboratory, National Center for Biotechnology, CSIC, Madrid, Spain
| | - Cristina Risco
- Cell Structure Laboratory, National Center for Biotechnology, CSIC, Madrid, Spain.
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Abstract
Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. Due to the asymptomatic nature of the infection, many acute cases of HCV infection are left undiagnosed, so screening individuals at risk is an important public health priority. New medications offer sustained virologic response rates of over 95%, fewer adverse reactions, and shorter durations of therapy. This article reviews the new treatment guidelines for the evaluation and management of patients with HCV infection.
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Dvory-Sobol H, Han B, Lu J, Yu M, Beran RK, Cheng G, Martin R, Svarovskaia E, Mo H. In vitro resistance profile of hepatitis C virus NS5A inhibitor velpatasvir in genotypes 1 to 6. J Viral Hepat 2019; 26:991-1001. [PMID: 31009123 DOI: 10.1111/jvh.13116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 03/28/2019] [Accepted: 03/29/2019] [Indexed: 12/29/2022]
Abstract
Velpatasvir is a pan-genotypic hepatitis C virus (HCV) NS5A inhibitor, which is used with sofosbuvir for treatment of infection with HCV genotypes 1-6. In vitro resistance studies were performed to characterize NS5A changes that might confer reduced velpatasvir susceptibility in vivo. Resistance selection studies using HCV replicon cells for subtypes 1a, 1b, 2a, 2b, 3a, 4a, 5a and 6a identified NS5A resistance-associated substitutions (RASs) at nine positions, most often 28M/S/T, 31F/I/M/P/V and 93D/H/N/S. In subtype 1a, RASs were selected at positions 31 and/or 93, while in subtype 1b, replicons with two or more RASs at positions 31, 54 or 93 were selected. Y93H was selected in subtypes 1a, 1b, 2a, 3a and 4a. In subtype 5a or 6a, L31P or P32L/Q was selected, respectively. Velpatasvir susceptibility of 358 replicons from genotypes 1 to 6 containing one or more NS5A RASs was also evaluated. The majority (63%) of subtypes 1a and 1b single RAS-containing replicons retained susceptibility to velpatasvir (<2.5-fold change in EC50 ). High levels of resistance to velpatasvir were observed for six single mutants in subtype 1a, including M28G, A92K, Y93H/N/R/W and for one mutant, A92K, in subtype 1b. Most single mutants in subtypes 2a, 2b, 3a, 4a and 5a displayed low levels of reduced velpatasvir susceptibility. High-level resistance was observed for C92T and Y93H/N in subtype 2b, Y93H/S in 3a, and L31V and P32A/L/Q/R in 6a, and several double mutants in these subtypes. Overall, velpatasvir maintained activity against most common RASs that are known to confer resistance to first-generation NS5A inhibitors.
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Affiliation(s)
| | - Bin Han
- Gilead Sciences, Foster City, California
| | - Julia Lu
- Gilead Sciences, Foster City, California
| | - Mei Yu
- Gilead Sciences, Foster City, California
| | | | | | | | | | - Hongmei Mo
- Gilead Sciences, Foster City, California
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Boseila AA, Abdel-Reheem AY, Basalious EB. Design of bile-based vesicles (BBVs) for hepatocytes specific delivery of Daclatasvir: Comparison of ex-vivo transenterocytic transport, in-vitro protein adsorption resistance and HepG2 cellular uptake of charged and β-sitosterol decorated vesicles. PLoS One 2019; 14:e0219752. [PMID: 31310613 PMCID: PMC6634393 DOI: 10.1371/journal.pone.0219752] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/01/2019] [Indexed: 01/04/2023] Open
Abstract
Daclatasvir is a new direct acting antiviral used in treatment of Hepatitis C virus, in an attempt to increase its hepatocytes specificity and uptake. It was encapsulated within bile based vesicles (BBVs) containing egg phosphatidyl choline, cholesterol and sodium deoxycholate fabricated by thin-film hydration method. A D-optimal mixture design was applied to study the effect of formulation variables on vesicular characteristics. The dependent variables picked were the particle size, polydispersity index, zeta potential and entrapment efficiency. The optimized bile based vesicles were subjected for further modifications to prepare miniaturized anionic (ABBVs), cationic (CBBVs) and Sito-G decorated BBVs (Sito-GBBVs) to be capable to penetrate liver fenestrae (<200 nm). The aim of the current work is to compare the potential of the ABBVs, CBBVs and Sito-GBBVs loaded with Daclatasvir for stability in simulated biological fluids, ex-vivo intestinal transenterocytic transport, HepG2 cellular uptake and resistance to blood protein adsorption. The miniaturized ABBVs, CBBVs and Sito-GBBVs showed acceptable stability in simulated biological fluids. CBBVs had the highest transenterocytic transport through intestinal membrane. The internalization of CBBVs into HepG2 cells was about 2.1 folds that of ABBVs and 1.45 folds that of Sito-GBBVs. ABBVs and Sito-GBBVs showed superior resistance to opsonization compared to CBBVs which showed significant increase in particle size (p˃0.05) due to protein adsorption. The miniaturized Sito-GBBVs constitute a promising strategy to overcome key biological barriers facing hepatocytes specific delivery of Daclatasvir.
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Affiliation(s)
- Amira A. Boseila
- Department of Pharmaceutics, National Organization for Drug Control and Research, Cairo, Egypt
- * E-mail:
| | - Amal Y. Abdel-Reheem
- Department of Pharmaceutics, National Organization for Drug Control and Research, Cairo, Egypt
| | - Emad B. Basalious
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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García-Serradilla M, Risco C, Pacheco B. Drug repurposing for new, efficient, broad spectrum antivirals. Virus Res 2019; 264:22-31. [PMID: 30794895 PMCID: PMC7114681 DOI: 10.1016/j.virusres.2019.02.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/18/2019] [Accepted: 02/18/2019] [Indexed: 12/26/2022]
Abstract
Emerging viruses are a major threat to human health. Recent outbreaks have emphasized the urgent need for new antiviral treatments. For several pathogenic viruses, considerable efforts have focused on vaccine development. However, during epidemics infected individuals need to be treated urgently. High-throughput screening of clinically tested compounds provides a rapid means to identify undiscovered, antiviral functions for well-characterized therapeutics. Repurposed drugs can bypass part of the early cost and time needed for validation and authorization. In this review we describe recent efforts to find broad spectrum antivirals through drug repurposing. We have chosen several candidates and propose strategies to understand their mechanism of action and to determine how resistance to antivirals develops in infected cells.
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Affiliation(s)
- Moisés García-Serradilla
- Cell Structure Laboratory, National Center for Biotechnology, National Research Council, CNB-CSIC, Darwin 3, UAM, campus de Cantoblanco, 28049 Madrid, Spain
| | - Cristina Risco
- Cell Structure Laboratory, National Center for Biotechnology, National Research Council, CNB-CSIC, Darwin 3, UAM, campus de Cantoblanco, 28049 Madrid, Spain.
| | - Beatriz Pacheco
- Cell Structure Laboratory, National Center for Biotechnology, National Research Council, CNB-CSIC, Darwin 3, UAM, campus de Cantoblanco, 28049 Madrid, Spain.
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A retrospective study of the efficacy of sofosbuvir plus NS5A inhibitors for patients with hepatitis C virus genotype-2 chronic infection. Eur J Gastroenterol Hepatol 2019; 31:382-388. [PMID: 30383554 DOI: 10.1097/meg.0000000000001299] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND A combination of sofosbuvir (SOF)+NS5A inhibitor therapies is the main treatment for patients with hepatitis C virus (HCV) genotype-2 (GT-2) chronic infection, but the data are rarely reported in China. This study aimed to investigate the virological response and liver fibrosis improvement among GT-2 patients receiving SOF+NS5A inhibitors. PATIENTS AND METHODS In this retrospective study, patients who received SOF+NS5A inhibitors between March 2016 and July 2017 were recruited. The treatment duration was 12 weeks and the treatment strategies included SOF+daclatasvir, SOF/ledipasvir, and SOF/velpatasvir. The primary endpoint was a sustained virologic response (serum HCV RNA undetectable) at week 12 after the end of therapy and the secondary endpoint was the improvement in liver stiffness and scores of apartate aminotransferase to platelet ratio index and fibrosis-4. RESULTS A total of 30 GT-2 patients were enrolled, with 13 (43.3%) patients in SOF+daclatasvir, 13 (43.3%) patients in SOF/ledipasvir, and four (13.3%) patients in SOF/velpatasvir. All patients [30/30 (100%)] achieved SVR, irrespective of treatment regimens and degree of liver fibrosis. After the treatment, liver fibrosis scores of apartate aminotransferase to platelet ratio index (2.27±2.14 vs. 0.89±0.77, P=0.003) and fibrosis-4 (1.17±1.22 vs. 0.42±0.25, P=0.013) were both significantly lower than those before treatment. CONCLUSION SOF+NS5A inhibitor therapies may induce an excellent virological response and fibrosis improvement in HCV GT-2-infected patients.
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Alazard-Dany N, Denolly S, Boson B, Cosset FL. Overview of HCV Life Cycle with a Special Focus on Current and Possible Future Antiviral Targets. Viruses 2019; 11:v11010030. [PMID: 30621318 PMCID: PMC6356578 DOI: 10.3390/v11010030] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 12/31/2018] [Accepted: 01/02/2019] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C infection is the leading cause of liver diseases worldwide and a major health concern that affects an estimated 3% of the global population. Novel therapies available since 2014 and 2017 are very efficient and the WHO considers HCV eradication possible by the year 2030. These treatments are based on the so-called direct acting antivirals (DAAs) that have been developed through research efforts by academia and industry since the 1990s. After a brief overview of the HCV life cycle, we describe here the functions of the different targets of current DAAs, the mode of action of these DAAs and potential future inhibitors.
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Affiliation(s)
- Nathalie Alazard-Dany
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
| | - Solène Denolly
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
| | - Bertrand Boson
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
| | - François-Loïc Cosset
- CIRI-Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
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Abstract
The advent of direct-acting antivirals (DAAs) has brought about a sudden renaissance in the treatment of chronic hepatitis C virus (HCV) infection with SVR rates now routinely >90%. However, due to the error-prone nature of the HCV RNA polymerase, resistance-associated substitutions (RASs) to DAAs may be present at baseline and can result in a significant effect on treatment outcomes and hamper the achievement of sustained virologic response. By further understanding the patterns and nature of these RASs, it is anticipated that the incidence of treatment failure will continue to decrease in frequency with the development of drug regimens with increasing potency, barrier to resistance, and genotypic efficacy. This review summarizes our current knowledge of RASs associated with HCV infection as well as the clinical effect of RASs on treatment with currently available DAA regimens.
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Affiliation(s)
- Darrick K Li
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - Raymond T Chung
- Liver Center and Division of Gastroenterology, Department of Medicine, Massachusetts General Hospital, Boston, MA, USA.
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Schenk C, Meyrath M, Warnken U, Schnölzer M, Mier W, Harak C, Lohmann V. Characterization of a Threonine-Rich Cluster in Hepatitis C Virus Nonstructural Protein 5A and Its Contribution to Hyperphosphorylation. J Virol 2018; 92:JVI.00737-18. [PMID: 30258001 PMCID: PMC6258934 DOI: 10.1128/jvi.00737-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 09/20/2018] [Indexed: 12/13/2022] Open
Abstract
Hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a phosphoprotein with key functions in regulating viral RNA replication and assembly. Two phosphoisoforms are discriminated by their different apparent molecular weights: a basally phosphorylated (p56) and a hyperphosphorylated (p58) variant. The precise mechanisms governing p58 synthesis and specific functions of the isoforms are poorly understood. Our study aimed at a deeper understanding of determinants involved in p58 synthesis. We analyzed two variants of p56 and p58 of isolate JFH-1 separately by mass spectrometry using an expression model and thereby identified a threonine-rich phosphopeptide exclusively found in the hyperphosphorylated variant. Individual exchange of possible phosphoacceptor sites to phosphoablatant or -mimetic residues had little impact on HCV replication or assembly in cell culture. A phosphospecific antibody recognizing pT242 revealed that this position was indeed phosphorylated only in p58 and depended on casein kinase Iα. Importantly, phosphoablative mutations at positions T244 and S247 abrogated pT242 detection without substantial effects on global p58 levels, whereas mutations in the preceding serine-rich cluster dramatically reduced total p58 levels but had minor impact on pT242 levels, suggesting the existence of distinct subspecies of hyperphosphorylated NS5A. Mass spectrometry analyses of different genotypes showed variable phosphorylation patterns across NS5A and suggested that the threonine-rich region is also phosphorylated at T242 in gt4a and at S249 in gt1a, gt1b, and gt4a. Our data therefore indicate that p58 is not a single homogenously phosphorylated protein species but rather a population of various phosphoisoforms, with high variability between genotypes.IMPORTANCE Hepatitis C virus infections affect 71 million people worldwide and cause severe chronic liver disease. Recently, efficient antiviral therapies have been established, with inhibitors of nonstructural protein NS5A as a cornerstone. NS5A is a central regulator of HCV replication and assembly but is still enigmatic in its molecular functions. It exists in two phosphoisoforms, p56 and p58. We identified a phosphopeptide exclusively found in p58 and analyzed the determinants involved in phosphorylation of this region. We found evidence for very different phosphorylation patterns resulting in p58. These results challenge the concept of p58 being a homogenous species of NS5A molecules phosphorylated at the same positions and argues for at least two independently phosphorylated variants showing the same electrophoretic mobility, likely serving different functions.
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Affiliation(s)
- Christian Schenk
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Max Meyrath
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Uwe Warnken
- Functional Proteome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Martina Schnölzer
- Functional Proteome Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Walter Mier
- Department of Nuclear Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Christian Harak
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Volker Lohmann
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
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Zhang Y, Zou J, Zhao X, Yuan Z, Yi Z. Hepatitis C virus NS5A inhibitor daclatasvir allosterically impairs NS4B-involved protein-protein interactions within the viral replicase and disrupts the replicase quaternary structure in a replicase assembly surrogate system. J Gen Virol 2018; 100:69-83. [PMID: 30516462 DOI: 10.1099/jgv.0.001180] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Daclatasvir (DCV) is a highly potent direct-acting antiviral that targets the non-structural protein 5A (NS5A) of hepatitis C virus (HCV) and has been used with great clinical success. Previous studies have demonstrated its impact on viral replication complex assembly. However, the precise mechanisms by which DCV impairs the replication complex assembly remains elusive. In this study, by using HCV subgenomic replicons and a viral replicase assembly surrogate system in which the HCV NS3-5B polyprotein is expressed to mimic the viral replicase assembly, we assessed the impact of DCV on the aggregation and tertiary structure of NS5A, the protein-protein interactions within the viral replicase and the quaternary structure of the viral replicase. We found that DCV did not affect aggregation and tertiary structure of NS5A. DCV induced a quaternary structural change of the viral replicase, as evidenced by selective increase of NS4B's sensitivity to proteinase K digestion. Mechanically, DCV impaired the NS4B-involved protein-protein interactions within the viral replicase. These phenotypes were consistent with the phenotypes of several reported NS4B mutants that abolish the viral replicase assembly. The DCV-resistant mutant Y93H was refractory to the DCV-induced reduction of the NS4B-involved protein interactions and the quaternary structural change of the viral replicase. In addition, Y93H reduced NS4B-involved protein-protein interactions within the viral replicase and attenuated viral replication. We propose that DCV may induce a positional change of NS5A, which allosterically affects protein interactions within the replicase components and disrupts replicase assembly.
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Affiliation(s)
- Yang Zhang
- 1Key Laboratory of Medical Molecular Virology and Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Jingyi Zou
- 1Key Laboratory of Medical Molecular Virology and Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Xiaomin Zhao
- 1Key Laboratory of Medical Molecular Virology and Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Zhenghong Yuan
- 1Key Laboratory of Medical Molecular Virology and Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
| | - Zhigang Yi
- 2Department of Pathogen Diagnosis and Biosafety, Shanghai Public Health Clinical Center, Fudan University, Shanghai, PR China.,1Key Laboratory of Medical Molecular Virology and Department of Medical Microbiology, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, PR China
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40
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Ashraf MU, Iman K, Khalid MF, Salman HM, Shafi T, Rafi M, Javaid N, Hussain R, Ahmad F, Shahzad-Ul-Hussan S, Mirza S, Shafiq M, Afzal S, Hamera S, Anwar S, Qazi R, Idrees M, Qureshi SA, Chaudhary SU. Evolution of efficacious pangenotypic hepatitis C virus therapies. Med Res Rev 2018; 39:1091-1136. [PMID: 30506705 DOI: 10.1002/med.21554] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 10/11/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022]
Abstract
Hepatitis C compromises the quality of life of more than 350 million individuals worldwide. Over the last decade, therapeutic regimens for treating hepatitis C virus (HCV) infections have undergone rapid advancements. Initially, structure-based drug design was used to develop molecules that inhibit viral enzymes. Subsequently, establishment of cell-based replicon systems enabled investigations into various stages of HCV life cycle including its entry, replication, translation, and assembly, as well as role of host proteins. Collectively, these approaches have facilitated identification of important molecules that are deemed essential for HCV life cycle. The expanded set of putative virus and host-encoded targets has brought us one step closer to developing robust strategies for efficacious, pangenotypic, and well-tolerated medicines against HCV. Herein, we provide an overview of the development of various classes of virus and host-directed therapies that are currently in use along with others that are undergoing clinical evaluation.
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Affiliation(s)
- Muhammad Usman Ashraf
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan.,Virology Laboratory, Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Kanzal Iman
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
| | - Muhammad Farhan Khalid
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan.,Department of Biomedical Engineering, University of Engineering and Technology, Lahore, Pakistan
| | - Hafiz Muhammad Salman
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan.,Plant Biotechnology Laboratory, Institute of Agricultural Sciences, University of the Punjab, Lahore, Pakistan
| | - Talha Shafi
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
| | - Momal Rafi
- Department of Statistics, University of Gujrat, Gujrat, Pakistan
| | - Nida Javaid
- Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
| | - Rashid Hussain
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
| | - Fayyaz Ahmad
- Department of Statistics, University of Gujrat, Gujrat, Pakistan
| | | | - Shaper Mirza
- Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
| | - Muhammad Shafiq
- Plant Biotechnology Laboratory, Institute of Agricultural Sciences, University of the Punjab, Lahore, Pakistan
| | - Samia Afzal
- Virology Laboratory, Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan
| | - Sadia Hamera
- Department of Plant Genetics, Institute of Life Sciences, University of Rostock, Germany
| | - Saima Anwar
- Department of Biomedical Engineering, University of Engineering and Technology, Lahore, Pakistan
| | - Romena Qazi
- Department of Pathology, Shaukat Khanum Memorial Cancer Hospital & Research Centre, Lahore, Pakistan
| | - Muhammad Idrees
- Virology Laboratory, Center of Excellence in Molecular Biology, University of the Punjab, Lahore, Pakistan.,Hazara University, Mansehra, Pakistan
| | - Sohail A Qureshi
- Institute of Integrative Biosciences, CECOS-University of Information Technology and Emerging Sciences, Peshawar, Pakistan
| | - Safee Ullah Chaudhary
- Biomedical Informatics Research Laboratory, Department of Biology, Lahore University of Management Sciences, Lahore, Pakistan
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41
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Hepatitis C virus cell culture models: an encomium on basic research paving the road to therapy development. Med Microbiol Immunol 2018; 208:3-24. [PMID: 30298360 DOI: 10.1007/s00430-018-0566-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 10/01/2018] [Indexed: 12/17/2022]
Abstract
Chronic hepatitis C virus (HCV) infections affect 71 million people worldwide, often resulting in severe liver damage. Since 2014 highly efficient therapies based on directly acting antivirals (DAAs) are available, offering cure rates of almost 100%, if the infection is diagnosed in time. It took more than a decade to discover HCV in 1989 and another decade to establish a cell culture model. This review provides a personal view on the importance of HCV cell culture models, particularly the replicon system, in the process of therapy development, from drug screening to understanding of mode of action and resistance, with a special emphasis on the contributions of Ralf Bartenschlager's group. It summarizes the tremendous efforts of scientists in academia and industry required to achieve efficient DAAs, focusing on the main targets, protease, polymerase and NS5A. It furthermore underpins the importance of strong basic research laying the ground for translational medicine.
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42
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Mingorance L, Castro V, Ávila-Pérez G, Calvo G, Rodriguez MJ, Carrascosa JL, Pérez-del-Pulgar S, Forns X, Gastaminza P. Host phosphatidic acid phosphatase lipin1 is rate limiting for functional hepatitis C virus replicase complex formation. PLoS Pathog 2018; 14:e1007284. [PMID: 30226904 PMCID: PMC6161900 DOI: 10.1371/journal.ppat.1007284] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 09/28/2018] [Accepted: 08/14/2018] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) infection constitutes a significant health burden worldwide, because it is a major etiologic agent of chronic liver disease, cirrhosis and hepatocellular carcinoma. HCV replication cycle is closely tied to lipid metabolism and infection by this virus causes profound changes in host lipid homeostasis. We focused our attention on a phosphatidate phosphate (PAP) enzyme family (the lipin family), which mediate the conversion of phosphatidate to diacylglycerol in the cytoplasm, playing a key role in triglyceride biosynthesis and in phospholipid homeostasis. Lipins may also translocate to the nucleus to act as transcriptional regulators of genes involved in lipid metabolism. The best-characterized member of this family is lipin1, which cooperates with lipin2 to maintain glycerophospholipid homeostasis in the liver. Lipin1-deficient cell lines were generated by RNAi to study the role of this protein in different steps of HCV replication cycle. Using surrogate models that recapitulate different aspects of HCV infection, we concluded that lipin1 is rate limiting for the generation of functional replicase complexes, in a step downstream primary translation that leads to early HCV RNA replication. Infection studies in lipin1-deficient cells overexpressing wild type or phosphatase-defective lipin1 proteins suggest that lipin1 phosphatase activity is required to support HCV infection. Finally, ultrastructural and biochemical analyses in replication-independent models suggest that lipin1 may facilitate the generation of the membranous compartment that contains functional HCV replicase complexes. Hepatitis C virus (HCV) infection is an important biomedical problem worldwide because it causes severe liver disease and cancer. Although immunological events are major players in HCV pathogenesis, interference with host cell metabolism contribute to HCV-associated pathologies. HCV utilizes resources of the cellular lipid metabolism to strongly modify subcellular compartments, using them as platforms for replication and infectious particle assembly. In particular, HCV induces the formation of a “membranous web” that hosts the viral machinery dedicated to the production of new copies of the viral genome. This lipid-rich structure provides an optimized platform for viral genome replication and hides new viral genomes from host´s antiviral surveillance. In this study, we have identified a cellular protein, lipin1, involved in the production of a subset of cellular lipids, as a rate-limiting factor for HCV infection. Our results indicate that the enzymatic activity of lipin1 is required to build the membranous compartment dedicated to viral genome replication. Lipin1 is probably contributing to the formation of the viral replication machinery by locally providing certain lipids required for an optimal membranous environment. Based on these results, interfering with lipin1 capacity to modify lipids may therefore constitute a potential strategy to limit HCV infection.
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Affiliation(s)
- Lidia Mingorance
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
| | - Victoria Castro
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
| | - Ginés Ávila-Pérez
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
| | - Gema Calvo
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
| | - María Josefa Rodriguez
- Department of Macromolecular Structures, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
| | - José L. Carrascosa
- Department of Macromolecular Structures, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
| | - Sofía Pérez-del-Pulgar
- Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Consorcio Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Universitat de Barcelona, Barcelona (Spain)
| | - Xavier Forns
- Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Consorcio Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Universitat de Barcelona, Barcelona (Spain)
| | - Pablo Gastaminza
- Department of Cellular and Molecular Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid (Spain)
- Liver Unit, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Consorcio Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Universitat de Barcelona, Barcelona (Spain)
- * E-mail:
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43
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Visualisation and analysis of hepatitis C virus non-structural proteins using super-resolution microscopy. Sci Rep 2018; 8:13604. [PMID: 30206266 PMCID: PMC6134135 DOI: 10.1038/s41598-018-31861-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 08/29/2018] [Indexed: 01/17/2023] Open
Abstract
Hepatitis C virus (HCV) RNA replication occurs in the cytosol of infected cells within a specialised membranous compartment. How the viral non-structural (NS) proteins are associated and organised within these structures remains poorly defined. We employed a super-resolution microscopy approach to visualise NS3 and NS5A in HCV infected cells. Using single molecule localisation microscopy, both NS proteins were resolved as clusters of localisations smaller than the diffraction-limited volume observed by wide-field. Analysis of the protein clusters identified a significant difference in size between the NS proteins. We also observed a reduction in NS5A cluster size following inhibition of RNA replication using daclatasvir, a phenotype which was maintained in the presence of the Y93H resistance associated substitution and not observed for NS3 clusters. These results provide insight into the NS protein organisation within hepatitis C virus RNA replication complexes and the mode of action of NS5A inhibitors.
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Santarella-Mellwig R, Haselmann U, Schieber NL, Walther P, Schwab Y, Antony C, Bartenschlager R, Romero-Brey I. Correlative Light Electron Microscopy (CLEM) for Tracking and Imaging Viral Protein Associated Structures in Cryo-immobilized Cells. J Vis Exp 2018. [PMID: 30247481 PMCID: PMC6235138 DOI: 10.3791/58154] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Due to its high resolution, electron microscopy (EM) is an indispensable tool for virologists. However, one of the main difficulties when analyzing virus-infected or transfected cells via EM are the low efficiencies of infection or transfection, hindering the examination of these cells. In order to overcome this difficulty, light microscopy (LM) can be performed first to allocate the subpopulation of infected or transfected cells. Thus, taking advantage of the use of fluorescent proteins (FPs) fused to viral proteins, LM is used here to record the positions of the "positive-transfected" cells, expressing a FP and growing on a support with an alphanumeric pattern. Subsequently, cells are further processed for EM via high pressure freezing (HPF), freeze substitution (FS) and resin embedding. The ultra-rapid freezing step ensures excellent membrane preservation of the selected cells that can then be analyzed at the ultrastructural level by transmission electron microscopy (TEM). Here, a step-by-step correlative light electron microscopy (CLEM) workflow is provided, describing sample preparation, imaging and correlation in detail. The experimental design can be also applied to address many cell biology questions.
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Affiliation(s)
| | - Uta Haselmann
- Department of Infectious Diseases, Molecular Virology, Heidelberg University
| | | | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University
| | | | | | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University; Heidelberg Partner Site, German Center for Infection Research;
| | - Inés Romero-Brey
- Department of Infectious Diseases, Molecular Virology, Heidelberg University;
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45
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Lee SH, Moon JS, Pak BY, Kim GW, Lee W, Cho H, Kim S, Kim SJ, Oh JW. HA1077 displays synergistic activity with daclatasvir against hepatitis C virus and suppresses the emergence of NS5A resistance-associated substitutions in mice. Sci Rep 2018; 8:12469. [PMID: 30127498 PMCID: PMC6102265 DOI: 10.1038/s41598-018-30460-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 07/31/2018] [Indexed: 02/08/2023] Open
Abstract
The kinase C-related kinase 2 (PRK2), which phosphorylates hepatitis C virus (HCV) RNA polymerase, is a proviral factor enhancing HCV replication. Here, we report on the in vivo anti-HCV efficacy of HA1077, which inhibits viral genome replication by targeting PRK2 and displays viral entry inhibitory activity by targeting Rho-associated kinase. HA1077 showed synergistic antiviral activity selectively with nonstructural protein 5 A (NS5A) inhibitors including daclatasvir (DCV). HA1077 oral administration substantially reduced serum viral loads in mice bearing HCV genotype 2a-replicating Huh7 xenografts. When administered with DCV, HA1077 potentiated the antiviral efficacy of DCV and suppressed the generation of DCV resistance-associated variants (RAVs). By deep-sequencing analysis, we uncovered an unprecedented DCV-induced polymorphism at the poly-proline motif (PxxPxxP) of NS5A. Coadministration of HA1077 reduced such a polymorphism. Overall, our results demonstrate the potential therapeutic benefit of combination therapy with HA1077 plus DCV for HCV patients carrying emerging or pre-existing RAVs toward NS5A inhibitors.
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Affiliation(s)
- Seung-Hoon Lee
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Jae-Su Moon
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Bo-Yeong Pak
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Geon-Woo Kim
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Wooseong Lee
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - Hee Cho
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea
| | - SangKyu Kim
- Department of Systems Immunology, Gangwon National University, Gangwon-do, 24341, Korea
| | - Seong-Jun Kim
- Center for Convergent Research of Emerging Virus Infection, Korea Research Institute of Chemical Technology, Daejeon, 34114, Korea
| | - Jong-Won Oh
- Department of Biotechnology, Yonsei University, Seoul, 03722, Korea.
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46
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Zhou S, Williford SE, McGivern DR, Burch CL, Hu F, Benzine T, Ingravallo P, Asante-Appiah E, Howe AYM, Swanstrom R, Lemon SM. Evolutionary pathways to NS5A inhibitor resistance in genotype 1 hepatitis C virus. Antiviral Res 2018; 158:45-51. [PMID: 30081054 DOI: 10.1016/j.antiviral.2018.07.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/27/2018] [Accepted: 07/30/2018] [Indexed: 01/04/2023]
Abstract
Direct-acting antivirals (DAAs) targeting NS5A are broadly effective against hepatitis C virus (HCV) infections, but sustained virological response rates are generally lower in patients infected with genotype (gt)-1a than gt-1b viruses. The explanation for this remains uncertain. Here, we adopted a highly accurate, ultra-deep primer ID sequencing approach to intensively study serial changes in the NS5A-coding region of HCV in gt-1a- and gt-1b-infected subjects receiving a short course of monotherapy with the NS5A inhibitor, elbasvir. Low or undetectable levels of viremia precluded on-treatment analysis in gt-1b-infected subjects, but variants with the resistance-associated substitution (RAS) Y93H in NS5A dominated rebounding virus populations following cessation of treatment. These variants persisted until the end of the study, two months later. In contrast, while Y93H emerged in multiple lineages and became dominant in subjects with gt-1a virus, these haplotypes rapidly decreased in frequency off therapy. Substitutions at Q30 and L31 emerged in distinctly independent lineages at later time points, ultimately coming to dominate the virus population off therapy. Consistent with this, cell culture studies with gt-1a and gt-1b reporter viruses and replicons demonstrated that Y93H confers a much greater loss of replicative fitness in gt-1a than gt-1b virus, and that L31M/V both compensates for the loss of fitness associated with Q30R (but not Y93H) and also boosts drug resistance. These observations show how differences in the impact of RASs on drug resistance and replicative fitness influence the evolution of gt-1a and gt-1b viruses during monotherapy with an antiviral targeting NS5A.
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Affiliation(s)
- Shuntai Zhou
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Sara E Williford
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - David R McGivern
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Christina L Burch
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Fengyu Hu
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Guangzhou Eighth People's Hospital, Guangzhou Medical University, Guangzhou, China
| | - Tiffany Benzine
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Paul Ingravallo
- Infectious Diseases, Merck Research Laboratory, Kenilworth, NJ, USA
| | | | - Anita Y M Howe
- Infectious Diseases, Merck Research Laboratory, Kenilworth, NJ, USA
| | - Ronald Swanstrom
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Stanley M Lemon
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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47
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Ramirez S, Bukh J. Current status and future development of infectious cell-culture models for the major genotypes of hepatitis C virus: Essential tools in testing of antivirals and emerging vaccine strategies. Antiviral Res 2018; 158:264-287. [PMID: 30059723 DOI: 10.1016/j.antiviral.2018.07.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 07/17/2018] [Accepted: 07/20/2018] [Indexed: 02/08/2023]
Abstract
In this review, we summarize the relevant scientific advances that led to the development of infectious cell culture systems for hepatitis C virus (HCV) with the corresponding challenges and successes. We also provide an overview of how these systems have contributed to the study of antiviral compounds and their relevance for the development of a much-needed vaccine against this major human pathogen. An efficient infectious system to study HCV in vitro, using human hepatoma derived cells, has only been available since 2005, and was limited to a single isolate, named JFH1, until 2012. Successive developments have been slow and cumbersome, as each available system has been the result of a systematic effort for discovering adaptive mutations conferring culture replication and propagation to patient consensus clones that are inherently non-viable in vitro. High genetic heterogeneity is a paramount characteristic of this virus, and as such, it should preferably be reflected in basic, translational, and clinical studies. The limited number of efficient viral culture systems, in the context of the vast genetic diversity of HCV, continues to represent a major hindrance for the study of this virus, posing a significant barrier towards studies of antivirals (particularly of resistance) and for advancing vaccine development. Intensive research efforts, driven by isolate-specific culture adaptation, have only led to efficient full-length infectious culture systems for a few strains of HCV genotypes 1, 2, 3, and 6. Hence research aimed at identifying novel strategies that will permit universal culture of HCV will be needed to further our understanding of this unique virus causing 400 thousand deaths annually.
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Affiliation(s)
- Santseharay Ramirez
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens Bukh
- Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital and Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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48
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Shanmugam S, Nichols AK, Saravanabalaji D, Welsch C, Yi M. HCV NS5A dimer interface residues regulate HCV replication by controlling its self-interaction, hyperphosphorylation, subcellular localization and interaction with cyclophilin A. PLoS Pathog 2018; 14:e1007177. [PMID: 30036383 PMCID: PMC6072203 DOI: 10.1371/journal.ppat.1007177] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 08/02/2018] [Accepted: 06/25/2018] [Indexed: 12/12/2022] Open
Abstract
The HCV NS5A protein plays multiple roles during viral replication, including viral genome replication and virus particle assembly. The crystal structures of the NS5A N-terminal domain indicated the potential existence of the NS5A dimers formed via at least two or more distinct dimeric interfaces. However, it is unknown whether these different forms of NS5A dimers are involved in its numerous functions. To address this question, we mutated the residues lining the two different NS5A dimer interfaces and determined their effects on NS5A self-interaction, NS5A-cyclophilin A (CypA) interaction, HCV RNA replication and infectious virus production. We found that the mutations targeting either of two dimeric interfaces disrupted the NS5A self-interaction in cells. The NS5A dimer-interrupting mutations also inhibited both viral RNA replication and infectious virus production with some genotypic differences. We also determined that reduced NS5A self-interaction was associated with altered NS5A-CypA interaction, NS5A hyperphosphorylation and NS5A subcellular localization, providing the mechanistic bases for the role of NS5A self-interaction in multiple steps of HCV replication. The NS5A oligomers formed via different interfaces are likely its functional form, since the residues at two different dimeric interfaces played similar roles in different aspects of NS5A functions and, consequently, HCV replication. In conclusion, this study provides novel insight into the functional significance of NS5A self-interaction in different steps of the HCV replication, potentially, in the form of oligomers formed via multiple dimeric interfaces. HCV NS5A is a multifunctional protein involved in both viral RNA replication and infectious virus production, and is a target of one of the most potent antivirals available to date. However, the mode of action of NS5A inhibitors is still unclear due to the lack of mechanistic detail regarding NS5A functions during HCV life cycles. In this study, we have provided evidence that surface-exposed NS5A residues involved in two different dimeric interactions in crystal structures are indeed involved in NS5A self-interactions in cells. We also showed that these NS5A residues play critical role in HCV RNA replication and infectious virus production by regulating NS5A hyperphosphorylation, its subcellular localization and its interaction with host protein CypA. Overall, our data support the functional significance of “NS5A oligomers” formed via multiple interfaces in HCV replication. We speculate that the NS5A inhibitors exploited the NS5A oligomer-dependent functions during HCV replication, rather than targeting individual NS5A, which consequently resulted in their high potency.
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Affiliation(s)
- Saravanabalaji Shanmugam
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Alyssa K. Nichols
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Dhanaranjani Saravanabalaji
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
| | - Christoph Welsch
- Department of Internal Medicine I, Goethe University, Frankfurt/Main, Germany
| | - MinKyung Yi
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, Texas, United States of America
- * E-mail:
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49
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Dornan GL, Dalwadi U, Hamelin DJ, Hoffmann RM, Yip CK, Burke JE. Probing the Architecture, Dynamics, and Inhibition of the PI4KIIIα/TTC7/FAM126 Complex. J Mol Biol 2018; 430:3129-3142. [PMID: 30031006 DOI: 10.1016/j.jmb.2018.07.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 07/11/2018] [Accepted: 07/16/2018] [Indexed: 11/16/2022]
Abstract
Phosphatidylinositol 4-kinase IIIα (PI4KIIIα) is the lipid kinase primarily responsible for generating the lipid phosphatidylinositol 4-phosphate (PI4P) at the plasma membrane, which acts as the substrate for generation of the signaling lipids PIP2 and PIP3. PI4KIIIα forms a large heterotrimeric complex with two regulatory partners, TTC7 and FAM126. We describe using an integrated electron microscopy and hydrogen-deuterium exchange mass spectrometry (HDX-MS) approach to probe the architecture and dynamics of the complex of PI4KIIIα/TTC7/FAM126. HDX-MS reveals that the majority of the PI4KIIIα sequence was protected from exchange in short deuterium pulse experiments, suggesting presence of secondary structure, even in putative unstructured regions. Negative stain electron microscopy reveals the shape and architecture of the full-length complex, revealing an overall dimer of PI4KIIIα/TTC7/FAM126 trimers. HDX-MS reveals conformational changes in the TTC7/FAM126 complex upon binding PI4KIIIα, including both at the direct TTC7-PI4KIIIα interface and at the putative membrane binding surface. Finally, HDX-MS experiments of PI4KIIIα bound to the highly potent and selective inhibitor GSK-A1 compared to that bound to the non-specific inhibitor PIK93 revealed substantial conformational changes throughout an extended region of the kinase domain. Many of these changes were distant from the putative inhibitor binding site, showing a large degree of allosteric conformational changes that occur upon inhibitor binding. Overall, our results reveal novel insight into the regulation of PI4KIIIα by its regulatory proteins TTC7/FAM126, as well as additional dynamic information on how selective inhibition of PI4KIIIα is achieved.
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Affiliation(s)
- Gillian L Dornan
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2
| | - Udit Dalwadi
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - David J Hamelin
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2
| | - Reece M Hoffmann
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2
| | - Calvin K Yip
- Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 2Y2.
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50
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van Buuren N, Tellinghuisen TL, Richardson CD, Kirkegaard K. Transmission genetics of drug-resistant hepatitis C virus. eLife 2018; 7:32579. [PMID: 29589830 PMCID: PMC5916564 DOI: 10.7554/elife.32579] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 03/22/2018] [Indexed: 12/11/2022] Open
Abstract
Antiviral development is plagued by drug resistance and genetic barriers to resistance are needed. For HIV and hepatitis C virus (HCV), combination therapy has proved life-saving. The targets of direct-acting antivirals for HCV infection are NS3/4A protease, NS5A phosphoprotein and NS5B polymerase. Differential visualization of drug-resistant and -susceptible RNA genomes within cells revealed that resistant variants of NS3/4A protease and NS5A phosphoprotein are cis-dominant, ensuring their direct selection from complex environments. Confocal microscopy revealed that RNA replication complexes are genome-specific, rationalizing the non-interaction of wild-type and variant products. No HCV antivirals yet display the dominance of drug susceptibility shown for capsid proteins of other viruses. However, effective inhibitors of HCV polymerase exact such high fitness costs for drug resistance that stable genome selection is not observed. Barriers to drug resistance vary with target biochemistry and detailed analysis of these barriers should lead to the use of fewer drugs. Viruses are simple organisms that consist of genetic information and a few types of proteins. They cannot replicate on their own, and instead hijack the molecular machinery of a host cell to produce more of themselves. Inside an infected cell, the genetic information of the virus is replicated and ‘read’ to create viral proteins. These components are then assembled to form a new generation of viruses. During this process, genetic errors may occur that lead to modifications in the viral proteins, and help the virus become resistant to treatment. For instance, a viral protein that used to be targeted by a drug can change slightly and not be recognized anymore. Currently, the most efficient way to fight drug resistance is to use combination therapy, where several drugs are given at the same time. This strategy is successful, for example to treat infections with the hepatitis C virus, but it is also expensive, especially for developing countries. An alternative approach is dominant-drug targeting, which exploits the fact that both drug-resistant and drug-susceptible viruses are ‘born’ in the same cell. There, the susceptible viruses can overwhelm and ‘mask’ the benefits of the resistant ones. For example, proteins from resistant strains, which are no longer detected by a treatment, can bind to proteins from susceptible viruses; drugs will still be able to recognize these resulting viral structures. The proteins that operate in such ways are potential dominant-drug targets. However, resistant and susceptible strains can also cohabit without any contacts if their proteins do not interact with each other. Now, van Buuren et al. screen several viral proteins, including one called NS5A, to test whether a dominant drug target exists for the hepatitis C virus. Only a few molecules of a drug that targets NS5A can stop the virus from growing. In theory, drug-bound NS5A proteins could block their non-drug-bound neighbors, but when these drugs have been used on their own, resistance quickly emerged. Experiments showed that NS5A is not a dominant drug target because the drug-resistant and drug-susceptible proteins do not mix. Unless ‘forced’ in the laboratory, NS5A proteins only bind to the ones produced by the same strain of virus. This explains why resistant viruses quickly take over when NS5A drugs are the sole treatment. However, other hepatitis C proteins, such as the HCV core protein, are known to mix during the assembly of the virus, and thus are likely be dominant drug targets.
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Affiliation(s)
- Nicholas van Buuren
- Department of Genetics, Stanford University School of Medicine, Stanford, United States
| | | | | | - Karla Kirkegaard
- Department of Genetics, Stanford University School of Medicine, Stanford, United States
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