51
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Cordek DG, Croom-Perez TJ, Hwang J, Hargittai MRS, Subba-Reddy CV, Han Q, Lodeiro MF, Ning G, McCrory TS, Arnold JJ, Koc H, Lindenbach BD, Showalter SA, Cameron CE. Expanding the proteome of an RNA virus by phosphorylation of an intrinsically disordered viral protein. J Biol Chem 2014; 289:24397-416. [PMID: 25031324 DOI: 10.1074/jbc.m114.589911] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The human proteome contains myriad intrinsically disordered proteins. Within intrinsically disordered proteins, polyproline-II motifs are often located near sites of phosphorylation. We have used an unconventional experimental paradigm to discover that phosphorylation by protein kinase A (PKA) occurs in the intrinsically disordered domain of hepatitis C virus non-structural protein 5A (NS5A) on Thr-2332 near one of its polyproline-II motifs. Phosphorylation shifts the conformational ensemble of the NS5A intrinsically disordered domain to a state that permits detection of the polyproline motif by using (15)N-, (13)C-based multidimensional NMR spectroscopy. PKA-dependent proline resonances were lost in the presence of the Src homology 3 domain of c-Src, consistent with formation of a complex. Changing Thr-2332 to alanine in hepatitis C virus genotype 1b reduced the steady-state level of RNA by 10-fold; this change was lethal for genotype 2a. The lethal phenotype could be rescued by changing Thr-2332 to glutamic acid, a phosphomimetic substitution. Immunofluorescence and transmission electron microscopy showed that the inability to produce Thr(P)-2332-NS5A caused loss of integrity of the virus-induced membranous web/replication organelle. An even more extreme phenotype was observed in the presence of small molecule inhibitors of PKA. We conclude that the PKA-phosphorylated form of NS5A exhibits unique structure and function relative to the unphosphorylated protein. We suggest that post-translational modification of viral proteins containing intrinsic disorder may be a general mechanism to expand the viral proteome without a corresponding expansion of the genome.
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Affiliation(s)
| | | | - Jungwook Hwang
- the Graduate School of Biomedical Science and Engineering, Hanyang University, 222 Wangsimri-ro, Seongdong-gu, Seoul, 133-791, Korea
| | | | - Chennareddy V Subba-Reddy
- the Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536, and
| | - Qingxia Han
- From the Department of Biochemistry and Molecular Biology
| | | | - Gang Ning
- the Huck Institutes of the Life Sciences, and
| | | | - Jamie J Arnold
- From the Department of Biochemistry and Molecular Biology
| | - Hasan Koc
- the Department of Pharmaceutical Science and Research, Marshall University School of Pharmacy, Huntington, West Virginia 25755
| | - Brett D Lindenbach
- the Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536, and
| | - Scott A Showalter
- the Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
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52
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Abstract
Hepatitis C virus (HCV) infection is curable by therapy. The antiviral treatment of chronic hepatitis C has been based for decades on the use of interferon (IFN)-α, combined with ribavirin. More recently, new therapeutic approaches that target essential components of the HCV life cycle have been developed, including direct-acting antiviral (DAA) and host-targeted agents (HTA). A new standard-of-care treatment has been approved in 2011 for patients infected with HCV genotype 1, based on a triple combination of pegylated IFN-α, ribavirin, and either telaprevir or boceprevir, two inhibitors of the HCV protease. New triple and quadruple combination therapies including pegylated IFN-α, ribavirin, and one or two DAAs/HTAs, respectively, are currently being evaluated in Phase II and III clinical trials. In addition, various options for all-oral, IFN-free regimens are currently being evaluated. This chapter describes the characteristics of the different drugs used in the treatment of chronic hepatitis C and those currently in development and provides an overview of the current and future standard-of-care treatments of chronic hepatitis C.
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Affiliation(s)
- Jean-Michel Pawlotsky
- National Reference Center for Viral Hepatitis B, C and D, Department of Virology, Hôpital Henri Mondor, Université Paris-Est, Créteil, France.
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53
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Comparison of daclatasvir resistance barriers on NS5A from hepatitis C virus genotypes 1 to 6: implications for cross-genotype activity. Antimicrob Agents Chemother 2014; 58:5155-63. [PMID: 24936600 DOI: 10.1128/aac.02788-14] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A comparison of the daclatasvir (DCV [BMS-790052]) resistance barrier on authentic or hybrid replicons containing NS5A from hepatitis C virus (HCV) genotypes 1 to 6 (GT-1 to -6) was completed using a replicon elimination assay. The data indicated that genotype 1b (GT-1b) has the highest relative resistance barrier and genotype 2a (GT-2a M31) has the lowest. The rank order of resistance barriers to DCV was 1b>4a≥5a>6a≅1a>2a JFH>3a>2a M31. Importantly, DCV in combination with a protease inhibitor (PI) eliminated GT-2a M31 replicon RNA at a clinically relevant concentration. Previously, we reported the antiviral activity and resistance profiles of DCV on HCV genotypes 1 to 4 evaluated in the replicon system. Here, we report the antiviral activity and resistance profiles of DCV against hybrid replicons with NS5A sequences derived from HCV GT-5a and GT-6a clinical isolates. DCV was effective against both GT-5a and -6a hybrid replicon cell lines (50% effective concentrations [EC50s] ranging from 3 to 7 pM for GT-5a, and 74 pM for GT-6a). Resistance selection identified amino acid substitutions in the N-terminal domain of NS5A. For GT-5a, L31F and L31V, alone or in combination with K56R, were the major resistance variants (EC50s ranging from 2 to 40 nM). In GT-6a, Q24H, L31M, P32L/S, and T58A/S were identified as resistance variants (EC50s ranging from 2 to 250 nM). The in vitro data suggest that DCV has the potential to be an effective agent for HCV genotypes 1 to 6 when used in combination therapy.
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54
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Schmidt WN, Nelson DR, Pawlotsky JM, Sherman KE, Thomas DL, Chung RT. Direct-acting antiviral agents and the path to interferon independence. Clin Gastroenterol Hepatol 2014; 12:728-37. [PMID: 23872239 PMCID: PMC4049632 DOI: 10.1016/j.cgh.2013.06.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 06/13/2013] [Accepted: 06/15/2013] [Indexed: 02/07/2023]
Abstract
Chronic infection with hepatitis C virus (HCV) is a major global health problem; there are approximately 120 to 130 million chronic infections worldwide. Since the discovery of HCV 24 years ago, there has been a relentless effort to develop successful antiviral therapies. Studies of interferon-α-based therapies have helped define treatment parameters, and these treatment strategies have cured a substantial percentage of patients. However, interferon-α must be injected; there are problems with tolerability, adherence, and incomplete response in a large percentage of patients. New drug candidates designed to target the virus or the host have recently been introduced at an unprecedented pace. In phase I-III studies, these agents have exceeded expectations and achieved rates of response previously not thought possible. We are, therefore, entering a new era of therapy for HCV infection and interferon independence.
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Affiliation(s)
- Warren N Schmidt
- Department of Internal Medicine and Research Service, Veterans Affairs Medical Center, Iowa City, Iowa; Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa.
| | - David R Nelson
- University of Florida, Section of Hepatobiliary Disease, Gainesville, Florida
| | - Jean-Michel Pawlotsky
- National Reference Center for Viral Hepatitis B, C and Delta, Department of Virology, Henri Mondor Hospital, University of Paris-Est, Créteil, France; INSERM U955, Créteil, France
| | - Kenneth E Sherman
- University of Cincinnati, College of Medicine, Division of Digestive Diseases, Hepatology Section, Cincinnati, Ohio
| | | | - Raymond T Chung
- GI Division and Liver Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts
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55
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Ascher DB, Wielens J, Nero TL, Doughty L, Morton CJ, Parker MW. Potent hepatitis C inhibitors bind directly to NS5A and reduce its affinity for RNA. Sci Rep 2014; 4:4765. [PMID: 24755925 PMCID: PMC3996483 DOI: 10.1038/srep04765] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 04/07/2014] [Indexed: 12/23/2022] Open
Abstract
Hepatitis C virus (HCV) infection affects more than 170 million people. The high genetic variability of HCV and the rapid development of drug-resistant strains are driving the urgent search for new direct-acting antiviral agents. A new class of agents has recently been developed that are believed to target the HCV protein NS5A although precisely where they interact and how they affect function is unknown. Here we describe an in vitro assay based on microscale thermophoresis and demonstrate that two clinically relevant inhibitors bind tightly to NS5A domain 1 and inhibit RNA binding. Conversely, RNA binding inhibits compound binding. The compounds bind more weakly to known resistance mutants L31V and Y93H. The compounds do not affect NS5A dimerisation. We propose that current NS5A inhibitors act by favouring a dimeric structure of NS5A that does not bind RNA.
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Affiliation(s)
- David B. Ascher
- ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia
| | - Jerome Wielens
- ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia
- Department of Medicine, University of Melbourne, 41 Victoria Parade, Fitzroy, Victoria 3065, Australia
| | - Tracy L. Nero
- ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia
| | - Larissa Doughty
- ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia
| | - Craig J. Morton
- ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia
| | - Michael W. Parker
- ACRF Rational Drug Discovery Centre and Biota Structural Biology Laboratory, St Vincent's Institute of Medical Research, 9 Princes Street, Fitzroy, Victoria 3056, Australia
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3052, Australia
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56
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Belema M, Meanwell NA. Discovery of daclatasvir, a pan-genotypic hepatitis C virus NS5A replication complex inhibitor with potent clinical effect. J Med Chem 2014; 57:5057-71. [PMID: 24749835 DOI: 10.1021/jm500335h] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The discovery and development of the first-in-class hepatitis C virus (HCV) NS5A replication complex inhibitor daclatasvir (6) provides a compelling example of the power of phenotypic screening to identify leads engaging novel targets in mechanistically unique ways. HCV NS5A replication complex inhibitors are pan-genotypic in spectrum, and this mechanistic class provides the most potent HCV inhibitors in vitro that have been described to date. Clinical trials with 6 demonstrated a potent effect on reducing plasma viral load and, in combination with mechanistically orthogonal HCV inhibitors, established the ability to cure even the most difficult infections without the need for immune stimulation. In this Drug Annotation, we describe the discovery of the original high-throughput screening lead 7 and the chemical conundrum and challenges resolved in optimizing to 6 as a clinical candidate and finally we summarize the results of select clinical studies.
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Affiliation(s)
- Makonen Belema
- Department of Discovery Chemistry, Bristol-Myers Squibb Research and Development , 5 Research Parkway, Wallingford, Connecticut 06492, United States
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57
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Barakat KH, Anwar-Mohamed A, Tuszynski JA, Robins MJ, Tyrrell DL, Houghton M. A Refined Model of the HCV NS5A protein bound to daclatasvir explains drug-resistant mutations and activity against divergent genotypes. J Chem Inf Model 2014; 55:362-73. [PMID: 24730573 DOI: 10.1021/ci400631n] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Many direct-acting antiviral agents (DAAs) that selectively block hepatitis C virus (HCV) replication are currently under development. Among these agents is Daclatasvir, a first-in-class inhibitor targeting the NS5A viral protein. Although Daclatasvir is the most potent HCV antiviral molecule yet developed, its binding location and mode of binding remain unknown. The drug exhibits a low barrier to resistance mutations, particularly in genotype 1 viruses, but its efficacy against other genotypes is unclear. Using state-of-the-art modeling techniques combined with the massive computational power of Blue Gene/Q, we identified the atomic interactions of Daclatasvir within NS5A for different HCV genotypes and for several reported resistant mutations. The proposed model is the first to reveal the detailed binding mode of Daclatasvir. It also provides a tool to facilitate design of second generation drugs, which may confer less resistance and/or broader activity against HCV.
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Affiliation(s)
- Khaled H Barakat
- Li Ka Shing Institute of Virology, University of Alberta , Edmonton, Alberta Canada
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58
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Kazmierski WM, Maynard A, Duan M, Baskaran S, Botyanszki J, Crosby R, Dickerson S, Tallant M, Grimes R, Hamatake R, Leivers M, Roberts CD, Walker J. Novel spiroketal pyrrolidine GSK2336805 potently inhibits key hepatitis C virus genotype 1b mutants: from lead to clinical compound. J Med Chem 2014; 57:2058-73. [PMID: 24568313 DOI: 10.1021/jm4013104] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Rapid clinical progress of hepatitis C virus (HCV) replication inhibitors, including these selecting for resistance in the NS5A region (NS5A inhibitors), promises to revolutionize HCV treatment. Herein, we describe our explorations of diverse spiropyrrolidine motifs in novel NS5A inhibitors and a proposed interaction model. We discovered that the 1,4-dioxa-7-azaspiro[4.4]nonane motif in inhibitor 41H (GSK2236805) supported high potency against genotypes 1a and 1b as well as in genotype 1b L31V and Y93H mutants. Consistent with this, 41H potently suppressed HCV RNA in the 20-day RNA reduction assay. Pharmacokinetic and safety data supported further progression of 41H to the clinic.
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Affiliation(s)
- Wieslaw M Kazmierski
- GlaxoSmithKline , 5 Moore Drive, Research Triangle Park, North Carolina 27709-3398, United States
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59
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Belema M, Nguyen VN, Bachand C, Deon DH, Goodrich JT, James CA, Lavoie R, Lopez OD, Martel A, Romine JL, Ruediger EH, Snyder LB, St Laurent DR, Yang F, Zhu J, Wong HS, Langley DR, Adams SP, Cantor GH, Chimalakonda A, Fura A, Johnson BM, Knipe JO, Parker DD, Santone KS, Fridell RA, Lemm JA, O'Boyle DR, Colonno RJ, Gao M, Meanwell NA, Hamann LG. Hepatitis C virus NS5A replication complex inhibitors: the discovery of daclatasvir. J Med Chem 2014; 57:2013-32. [PMID: 24521299 DOI: 10.1021/jm401836p] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The biphenyl derivatives 2 and 3 are prototypes of a novel class of NS5A replication complex inhibitors that demonstrate high inhibitory potency toward a panel of clinically relevant HCV strains encompassing genotypes 1-6. However, these compounds exhibit poor systemic exposure in rat pharmacokinetic studies after oral dosing. The structure-activity relationship investigations that improved the exposure properties of the parent bis-phenylimidazole chemotype, culminating in the identification of the highly potent NS5A replication complex inhibitor daclatasvir (33) are described. An element critical to success was the realization that the arylglycine cap of 2 could be replaced with an alkylglycine derivative and still maintain the high inhibitory potency of the series if accompanied with a stereoinversion, a finding that enabled a rapid optimization of exposure properties. Compound 33 had EC50 values of 50 and 9 pM toward genotype-1a and -1b replicons, respectively, and oral bioavailabilities of 38-108% in preclinical species. Compound 33 provided clinical proof-of-concept for the NS5A replication complex inhibitor class, and regulatory approval to market it with the NS3/4A protease inhibitor asunaprevir for the treatment of HCV genotype-1b infection has recently been sought in Japan.
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Affiliation(s)
- Makonen Belema
- Departments of Discovery Chemistry, ‡Discovery Chemistry Synthesis, §Computer-Assisted Drug Design, and ¶Pharmaceutical Candidate Optimization, #Virology, Bristol-Myers Squibb Research and Development, 5 Research Parkway, Wallingford, Connecticut 06492, United States
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60
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Belema M, Lopez OD, Bender JA, Romine JL, St Laurent DR, Langley DR, Lemm JA, O'Boyle DR, Sun JH, Wang C, Fridell RA, Meanwell NA. Discovery and development of hepatitis C virus NS5A replication complex inhibitors. J Med Chem 2014; 57:1643-72. [PMID: 24621191 DOI: 10.1021/jm401793m] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Lead inhibitors that target the function of the hepatitis C virus (HCV) nonstructural 5A (NS5A) protein have been identified by phenotypic screening campaigns using HCV subgenomic replicons. The demonstration of antiviral activity in HCV-infected subjects by the HCV NS5A replication complex inhibitor (RCI) daclatasvir (1) spawned considerable interest in this mechanistic approach. In this Perspective, we summarize the medicinal chemistry studies that led to the discovery of 1 and other chemotypes for which resistance maps to the NS5A protein and provide synopses of the profiles of many of the compounds currently in clinical trials. We also summarize what is currently known about the NS5A protein and the studies using NS5A RCIs and labeled analogues that are helping to illuminate aspects of both protein function and inhibitor interaction. We conclude with a synopsis of the results of notable clinical trials with HCV NS5A RCIs.
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Affiliation(s)
- Makonen Belema
- Department of Discovery Chemistry, ‡Department of Virology Discovery, and §Department of Computer-Assisted Drug Design, Bristol-Myers Squibb Research and Development , 5 Research Parkway, Wallingford, Connecticut 06492, United States
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61
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Ahn J, Flamm SL. Frontiers in the treatment of hepatitis C virus infection. Gastroenterol Hepatol (N Y) 2014; 10:90-100. [PMID: 24803873 PMCID: PMC4011382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the United States, chronic hepatitis C virus (HCV) infection is the leading cause of blood-borne, virus-associated death related to advanced liver disease and the leading indication for liver transplantation. Although the diagnostic test for HCV has been available for more than 20 years, the majority of persons with HCV infection still have not received a diagnosis. This has led to a recent change in screening recommendations by the Centers for Disease Control and Prevention. Moreover, new medications were approved in 2011 after nearly a decade of minimal progress in the development of treatments for HCV infection. This was followed by the highly anticipated approval of sofosbuvir and simeprevir in 201 3. In the past 3 years, there has been an explosion of reports on medications from different classes, promising a dramatic expansion to an all-oral regimen for the treatment of HCV genotype 1 infection within the next few years. This article reviews the current screening recommendations and standard of care for treatment of HCV infection and highlights specific agents in the pipeline that should change the landscape of how HCV infection is treated in the near future.
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Affiliation(s)
- Joseph Ahn
- Dr Ahn is an associate professor of medicine at the Oregon Health & Science University in Portland, Oregon. Dr Flamm is a professor of medicine at the Northwestern University Feinberg School of Medicine in Chicago, Illinois
| | - Steven L Flamm
- Dr Ahn is an associate professor of medicine at the Oregon Health & Science University in Portland, Oregon. Dr Flamm is a professor of medicine at the Northwestern University Feinberg School of Medicine in Chicago, Illinois
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62
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Dynamic imaging of the hepatitis C virus NS5A protein during a productive infection. J Virol 2014; 88:3636-52. [PMID: 24429364 DOI: 10.1128/jvi.02490-13] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
UNLABELLED Hepatitis C virus (HCV) NS5A is essential for viral genome replication within cytoplasmic replication complexes and virus assembly at the lipid droplet (LD) surface, although its definitive functions are poorly understood. We developed approaches to investigate NS5A dynamics during a productive infection. We report here that NS5A motility and efficient HCV RNA replication require the microtubule network and the cytoplasmic motor dynein and demonstrate that both motile and relatively static NS5A-positive foci are enriched with host factors VAP-A and Rab5A. Pulse-chase imaging revealed that newly synthesized NS5A foci are small and distinct from aged foci, while further studies using a unique dual fluorescently tagged infectious HCV chimera showed a relatively stable association of NS5A foci with core-capped LDs. These results reveal new details about the dynamics and maturation of NS5A and the nature of potential sites of convergence of HCV replication and assembly pathways. IMPORTANCE Hepatitis C virus (HCV) is a major cause of serious liver disease worldwide. An improved understanding of the HCV replication cycle will enable development of novel and improved antiviral strategies. Here we have developed complementary fluorescent labeling and imaging approaches to investigate the localization, traffic and interactions of the HCV NS5A protein in living, virus-producing cells. These studies reveal new details as to the traffic, composition and biogenesis of NS5A foci and the nature of their association with putative sites of virus assembly.
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63
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Ghosh B, Jones LH. Target validation using in-cell small molecule clickable imaging probes. MEDCHEMCOMM 2014. [DOI: 10.1039/c3md00277b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The application of click chemistry to the visualization of chemical probes in in-cell chemical biology experiments is reviewed and the influence this research has had on target validation and molecular mode of action studies is also highlighted.
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Affiliation(s)
| | - Lyn H. Jones
- Pfizer
- Chemical Biology Group
- BioTherapeutics Chemistry
- WorldWide Medicinal Chemistry
- Cambridge
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64
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Abstract
Chronic hepatitis C virus (HCV) infection is responsible for the development of liver cirrhosis and hepatocellular carcinoma. It has been a tremendous burden on global health care systems. With the advent of a number of new direct-acting and host-targeting antiviral agents, current interferon-α- and ribavirin-based HCV therapy has started to move towards an interferon-sparing or even interferon-free strategy. In this regard, a recently identified NS5A inhibitor, daclatasvir, showed a great promise in clinical trials as another new class of direct-acting anti-HCV therapeutics, with a distinct mechanism of action. In this review, a variety of preclinical as well as clinical proof-of-concept studies of daclatasvir, including the studies of its discovery, mechanism of action, viral resistance, and host polymorphism profiles are reviewed. In addition, a role of daclatasvir in the future therapy for HCV patients is discussed briefly.
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Affiliation(s)
- Choongho Lee
- College of Pharmacy, Dongguk University-Seoul, Goyang, Republic of Korea
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65
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Transient replication of a hepatitis C virus genotype 1b replicon chimera encoding NS5A-5B from genotype 3a. J Virol Methods 2013; 195:156-63. [PMID: 24120570 DOI: 10.1016/j.jviromet.2013.09.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/12/2013] [Accepted: 09/24/2013] [Indexed: 01/22/2023]
Abstract
Although hepatitis C virus (HCV) is a pathogen of global significance, experimental therapies in current clinical development include highly efficacious all-oral combinations of HCV direct-acting antivirals (DAAs). If approved for use, these new treatment regimens will impact dramatically upon our capacity to eradicate HCV in the majority of virus-infected patients. However, recent data from late-stage clinical evaluations demonstrated that individuals infected with HCV genotype (GT) 3 responded less well to all-oral DAA combinations than patients infected with other HCV GTs. In light of these observations, the present study sought to expand the number of molecular tools available to investigate small molecule-mediated inhibition of HCV GT3 NS5A and NS5B proteins in preclinical tissue-culture systems. Accordingly, a novel subgenomic HCV replicon chimera was created by utilizing a GT1b backbone modified to produce NS5A and NS5B proteins from a consensus sequence generated from HCV GT3a genomic sequences deposited online at the European Hepatitis C Virus database. This approach avoided the need to isolate and amplify HCV genomes from sera derived from HCV-infected patients. The replicon chimera, together with a version engineered to express NS5A encoding a Y93H mutation, demonstrated levels of replication in transient assays robust enough to assess accurate antiviral activities of inhibitors representing different HCV DAA classes. Thus, the replicon chimera represents a new simple molecular tool suitable for drug discovery programmes aimed at investigating, understanding, and improving GT3a activities of HCV DAAs targeting NS5A or NS5B.
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66
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Bhattacharya D, Ansari IH, Hamatake R, Walker J, Kazmierski WM, Striker R. Pharmacological disruption of hepatitis C NS5A protein intra- and intermolecular conformations. J Gen Virol 2013; 95:363-372. [PMID: 23997183 DOI: 10.1099/vir.0.054569-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Non-structural 5A protein (NS5A) has emerged as an important pharmacological target for hepatitis C virus (HCV). However, little is known about the conformation of NS5A intracellularly or how NS5A inhibitors achieve the picomolar (pM) inhibition of virus replication. Here, we have presented two structurally related small molecules, one that potently inhibits HCV replication and selects for resistance in NS5A, and another that is inactive. Resistance to this antiviral was greater in genotype 1a than in genotype 1b replicons and mapped to domain 1 of NS5A. Using a novel cell-based assay that measures the intracellular proximity of fluorescent tags covalently attached to NS5A, we showed that only the active antiviral specifically disrupted the close proximity of inter- and intramolecular positions of NS5A. The active antiviral, termed compound 1, caused a repositioning of both the N and C termini of NS5A, including disruption of the close approximation of the N termini of two different NS5A molecules in a multimolecular complex. These data provide the first study of how antivirals that select resistance in domain 1 of NS5A alter the cellular conformation of NS5A. This class of antiviral disrupts the close proximity of the N termini of domain 1 in a NS5A complex but also alters the conformation of domain 3, and leads to large aggregates of NS5A. Current models predict that a multicomponent cocktail of antivirals is needed to treat HCV infection, so a mechanistic understanding of what each component does to the viral machinery will be important.
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Affiliation(s)
| | - Israrul H Ansari
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Jill Walker
- GlaxoSmithKline, 5 Moore Drive, 3.3204 RTP, NC 27709, USA
| | | | - Rob Striker
- W. S. Middleton Memorial Veteran's Hospital, Madison, WI 53706, USA.,Department of Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
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67
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Binder M, Sulaimanov N, Clausznitzer D, Schulze M, Hüber CM, Lenz SM, Schlöder JP, Trippler M, Bartenschlager R, Lohmann V, Kaderali L. Replication vesicles are load- and choke-points in the hepatitis C virus lifecycle. PLoS Pathog 2013; 9:e1003561. [PMID: 23990783 PMCID: PMC3749965 DOI: 10.1371/journal.ppat.1003561] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 07/02/2013] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C virus (HCV) infection develops into chronicity in 80% of all patients, characterized by persistent low-level replication. To understand how the virus establishes its tightly controlled intracellular RNA replication cycle, we developed the first detailed mathematical model of the initial dynamic phase of the intracellular HCV RNA replication. We therefore quantitatively measured viral RNA and protein translation upon synchronous delivery of viral genomes to host cells, and thoroughly validated the model using additional, independent experiments. Model analysis was used to predict the efficacy of different classes of inhibitors and identified sensitive substeps of replication that could be targeted by current and future therapeutics. A protective replication compartment proved to be essential for sustained RNA replication, balancing translation versus replication and thus effectively limiting RNA amplification. The model predicts that host factors involved in the formation of this compartment determine cellular permissiveness to HCV replication. In gene expression profiling, we identified several key processes potentially determining cellular HCV replication efficiency. Hepatitis C is a severe disease and a prime cause for liver transplantation. Up to 3% of the world's population are chronically infected with its causative agent, the Hepatitis C virus (HCV). This capacity to establish long (decades) lasting persistent infection sets HCV apart from other plus-strand RNA viruses typically causing acute, self-limiting infections. A prerequisite for its capacity to persist is HCV's complex and tightly regulated intracellular replication strategy. In this study, we therefore wanted to develop a comprehensive understanding of the molecular processes governing HCV RNA replication in order to pinpoint the most vulnerable substeps in the viral life cycle. For that purpose, we used a combination of biological experiments and mathematical modeling. Using the model to study HCV's replication strategy, we recognized diverse but crucial roles for the membraneous replication compartment of HCV in regulating RNA amplification. We further predict the existence of an essential limiting host factor (or function) required for establishing active RNA replication and thereby determining cellular permissiveness for HCV. Our model also proved valuable to understand and predict the effects of pharmacological inhibitors of HCV and might be a solid basis for the development of similar models for other plus-strand RNA viruses.
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Affiliation(s)
- Marco Binder
- Heidelberg University, Medical Faculty, Department of Infectious Diseases, Molecular Virology, Heidelberg, Germany
| | - Nurgazy Sulaimanov
- Technische Universität Dresden, Institute for Medical Informatics and Biometry, Dresden, Germany
- Heidelberg University, ViroQuant Research Group Modeling, BioQuant BQ26, Heidelberg, Germany
| | - Diana Clausznitzer
- Technische Universität Dresden, Institute for Medical Informatics and Biometry, Dresden, Germany
| | - Manuel Schulze
- Technische Universität Dresden, Institute for Medical Informatics and Biometry, Dresden, Germany
| | - Christian M. Hüber
- Heidelberg University, Medical Faculty, Department of Infectious Diseases, Molecular Virology, Heidelberg, Germany
| | - Simon M. Lenz
- Heidelberg University, Interdisciplinary Center for Scientific Computing (IWR), Simulation and Optimization Group, Heidelberg, Germany
| | - Johannes P. Schlöder
- Heidelberg University, Interdisciplinary Center for Scientific Computing (IWR), Simulation and Optimization Group, Heidelberg, Germany
| | - Martin Trippler
- University Hospital of Essen, Department of Gastroenterology and Hepatology, Essen, Germany
| | - Ralf Bartenschlager
- Heidelberg University, Medical Faculty, Department of Infectious Diseases, Molecular Virology, Heidelberg, Germany
| | - Volker Lohmann
- Heidelberg University, Medical Faculty, Department of Infectious Diseases, Molecular Virology, Heidelberg, Germany
| | - Lars Kaderali
- Technische Universität Dresden, Institute for Medical Informatics and Biometry, Dresden, Germany
- Heidelberg University, ViroQuant Research Group Modeling, BioQuant BQ26, Heidelberg, Germany
- * E-mail:
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68
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Salloum S, Wang H, Ferguson C, Parton RG, Tai AW. Rab18 binds to hepatitis C virus NS5A and promotes interaction between sites of viral replication and lipid droplets. PLoS Pathog 2013; 9:e1003513. [PMID: 23935497 PMCID: PMC3731246 DOI: 10.1371/journal.ppat.1003513] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 06/07/2013] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) is a single-stranded RNA virus that replicates on endoplasmic reticulum-derived membranes. HCV particle assembly is dependent on the association of core protein with cellular lipid droplets (LDs). However, it remains uncertain whether HCV assembly occurs at the LD membrane itself or at closely associated ER membranes. Furthermore, it is not known how the HCV replication complex and progeny genomes physically associate with the presumed sites of virion assembly at or near LDs. Using an unbiased proteomic strategy, we have found that Rab18 interacts with the HCV nonstructural protein NS5A. Rab18 associates with LDs and is believed to promote physical interaction between LDs and ER membranes. Active (GTP-bound) forms of Rab18 bind more strongly to NS5A than a constitutively GDP-bound mutant. NS5A colocalizes with Rab18-positive LDs in HCV-infected cells, and Rab18 appears to promote the physical association of NS5A and other replicase components with LDs. Modulation of Rab18 affects genome replication and possibly also the production of infectious virions. Our results support a model in which specific interactions between viral and cellular proteins may promote the physical interaction between membranous HCV replication foci and lipid droplets. Hepatitis C virus (HCV) chronically infects about 170 million people worldwide and can ultimately lead to liver failure and liver cancer. HCV, like other RNA viruses, exploits cellular proteins and membranes to promote their own replication and virion production. In particular, HCV replication occurs at membranes derived from the endoplasmic reticulum, while HCV virion assembly is believed to occur at or near cellular lipid droplets. In this work, we report that Rab18, a lipid droplet-associated cellular protein, binds to the viral protein NS5A, and that the silencing of Rab18 reduces the association of other HCV replication complex components with lipid droplets. These data are consistent with a model in which Rab18 promotes the physical interaction between sites of viral replication to lipid droplets. We also speculate that Rab18 may help to link sites of viral replication to sites of virion assembly. Understanding how viruses exploit cellular proteins may result in new methods of disrupting viral infection.
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Affiliation(s)
- Shadi Salloum
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Hongliang Wang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Charles Ferguson
- The University of Queensland, Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, Brisbane, Queensland, Australia
| | - Robert G. Parton
- The University of Queensland, Institute for Molecular Bioscience and Centre for Microscopy and Microanalysis, Brisbane, Queensland, Australia
| | - Andrew W. Tai
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States of America
- Division of Gastroenterology, Department of Internal Medicine, Ann Arbor Veterans Administration Health System, Ann Arbor, Michigan, United States of America
- * E-mail:
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69
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Pawlotsky JM. NS5A inhibitors in the treatment of hepatitis C. J Hepatol 2013; 59:375-82. [PMID: 23567084 DOI: 10.1016/j.jhep.2013.03.030] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 03/22/2013] [Accepted: 03/27/2013] [Indexed: 12/11/2022]
Abstract
Hepatitis C virus infection is a major health problem worldwide and no vaccine has yet been developed against this virus. In addition, currently approved pharmacotherapies achieve suboptimal cure rates and have side effects that result in non-compliance and premature treatment discontinuation. Significant research has been devoted to developing direct-acting antiviral agents that inhibit key viral functions. In particular, several novel drug candidates that inhibit the viral non-structural protein 5A (NS5A) have been demonstrated to possess high potency, pan-genotypic activity, and a high barrier to resistance. Clinical trials using combination therapies containing NS5A inhibitors have reported results that promise high cure rates and raise the possibility of developing interferon-free, all-oral regimens.
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Affiliation(s)
- Jean-Michel Pawlotsky
- National Reference Centre for Viral Hepatitis B, C and Delta, Department of Virology, Henri Mondor Hospital, University of Paris-Est, Créteil, France; INSERM U955, Créteil, France.
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O'Boyle Ii DR, Sun JH, Nower PT, Lemm JA, Fridell RA, Wang C, Romine JL, Belema M, Nguyen VN, Laurent DRS, Serrano-Wu M, Snyder LB, Meanwell NA, Langley DR, Gao M. Characterizations of HCV NS5A replication complex inhibitors. Virology 2013; 444:343-54. [PMID: 23896639 DOI: 10.1016/j.virol.2013.06.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/02/2013] [Accepted: 06/28/2013] [Indexed: 01/28/2023]
Abstract
The hepatitis C virus NS5A protein is an established and clinically validated target for antiviral intervention by small molecules. Characterizations are presented of compounds identified as potent inhibitors of HCV replication to provide insight into structural elements that interact with the NS5A protein. UV-activated cross linking and affinity isolation was performed with one series to probe the physical interaction between the inhibitors and the NS5A protein expressed in HCV replicon cells. Resistance mapping with the second series was used to determine the functional impact of specific inhibitor subdomains on the interaction with NS5A. The data provide evidence for a direct high-affinity interaction between these inhibitors and the NS5A protein, with the interaction dependent on inhibitor stereochemistry. The functional data supports a model of inhibition that implicates inhibitor binding by covalently combining distinct pharmacophores across an NS5A dimer interface to achieve maximal inhibition of HCV replication.
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Affiliation(s)
- Donald R O'Boyle Ii
- Bristol-Myers Squibb Research and Development, Department of Virology Discovery, 5 Research Parkway, Wallingford, CT 06492, USA.
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71
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Gao M. Antiviral activity and resistance of HCV NS5A replication complex inhibitors. Curr Opin Virol 2013; 3:514-20. [PMID: 23896281 DOI: 10.1016/j.coviro.2013.06.014] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 06/24/2013] [Accepted: 06/26/2013] [Indexed: 12/13/2022]
Abstract
Treatment of Hepatitis C Virus (HCV) infection is rapidly evolving with the introduction of direct acting antiviral agents (DAA). HCV NS5A replication complex inhibitors, exemplified by Daclatasvir (BMS-790052), represent a new class of DAA. The exceptional in vitro potency (EC50 values at pM to low nM range) and broad genotype coverage of NS5A inhibitors have translated to robust anti-HCV effects in infected patients, making NS5A inhibitors an essential component of effective HCV DAA combination therapies. On the basis of drug-induced resistance substitutions and computer modeling, NS5A inhibitors most likely act at the N-terminus of NS5A (domain I). Mechanism of inhibition studies to elucidate the exquisite potency of these inhibitors have generated several working models.
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Affiliation(s)
- Min Gao
- Bristol Myer Squibb Company, Wallingford, CT 06492, United States.
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72
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Inhibition of hepatitis C virus infection by DNA aptamer against envelope protein. Antimicrob Agents Chemother 2013; 57:4937-44. [PMID: 23877701 DOI: 10.1128/aac.00897-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Hepatitis C virus (HCV) envelope protein (E1E2) is essential for virus binding to host cells. Aptamers have been demonstrated to have strong promising applications in drug development. In the current study, a cDNA fragment encoding the entire E1E2 gene of HCV was cloned. E1E2 protein was expressed and purified. Aptamers for E1E2 were selected by the method of selective evolution of ligands by exponential enrichment (SELEX), and the antiviral actions of the aptamers were examined. The mechanism of their antiviral activity was investigated. The data show that selected aptamers for E1E2 specifically recognize the recombinant E1E2 protein and E1E2 protein from HCV-infected cells. CD81 protein blocks the binding of aptamer E1E2-6 to E1E2 protein. Aptamers against E1E2 inhibit HCV infection in an infectious cell culture system although they have no effect on HCV replication in a replicon cell line. Beta interferon (IFN-β) and IFN-stimulated genes (ISGs) are not induced in virus-infected hepatocytes with aptamer treatment, suggesting that E1E2-specific aptamers do not induce innate immunity. E2 protein is essential for the inhibition of HCV infection by aptamer E1E2-6, and the aptamer binding sites are located in E2. Q412R within E1E2 is the major resistance substitution identified. The data indicate that an aptamer against E1E2 exerts its antiviral effects through inhibition of virus binding to host cells. Aptamers against E1E2 can be used with envelope protein to understand the mechanisms of HCV entry and fusion. The aptamers may hold promise for development as therapeutic drugs for hepatitis C patients.
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73
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Inhibition of hepatitis C virus infection by DNA aptamer against envelope protein. Antimicrob Agents Chemother 2013. [PMID: 23877701 DOI: 10.1128/aac.00897] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Hepatitis C virus (HCV) envelope protein (E1E2) is essential for virus binding to host cells. Aptamers have been demonstrated to have strong promising applications in drug development. In the current study, a cDNA fragment encoding the entire E1E2 gene of HCV was cloned. E1E2 protein was expressed and purified. Aptamers for E1E2 were selected by the method of selective evolution of ligands by exponential enrichment (SELEX), and the antiviral actions of the aptamers were examined. The mechanism of their antiviral activity was investigated. The data show that selected aptamers for E1E2 specifically recognize the recombinant E1E2 protein and E1E2 protein from HCV-infected cells. CD81 protein blocks the binding of aptamer E1E2-6 to E1E2 protein. Aptamers against E1E2 inhibit HCV infection in an infectious cell culture system although they have no effect on HCV replication in a replicon cell line. Beta interferon (IFN-β) and IFN-stimulated genes (ISGs) are not induced in virus-infected hepatocytes with aptamer treatment, suggesting that E1E2-specific aptamers do not induce innate immunity. E2 protein is essential for the inhibition of HCV infection by aptamer E1E2-6, and the aptamer binding sites are located in E2. Q412R within E1E2 is the major resistance substitution identified. The data indicate that an aptamer against E1E2 exerts its antiviral effects through inhibition of virus binding to host cells. Aptamers against E1E2 can be used with envelope protein to understand the mechanisms of HCV entry and fusion. The aptamers may hold promise for development as therapeutic drugs for hepatitis C patients.
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74
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Belema M, Meanwell NA, Bender JA, Lopez OD, Hewawasam P, Langley DR. Discovery and Clinical Validation of HCV Inhibitors Targeting the NS5A Protein. SUCCESSFUL STRATEGIES FOR THE DISCOVERY OF ANTIVIRAL DRUGS 2013. [DOI: 10.1039/9781849737814-00003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
HCV non‐structural protein 5A (NS5A) is a multifunctional protein that plays a diverse set of roles in the replication cycle of the virus. Although a significant level of effort has been invested over the past decade at characterizing this protein, our understanding and appreciation of its full structure and function remain far from complete. Despite these drawbacks, however, great strides have been made towards discovering potent HCV NS5A inhibitors that have exhibited promising efficacy in early clinical trials, and these inhibitors have the potential to become an integral component of effective combination therapies that are expected to emerge in the near future. Highlights of the biochemical characterization of the HCV NS5A protein, aspects of the seminal drug discovery effort that culminated in the identification of daclatasvir with which clinical proof‐of‐concept was obtained for NS5A as a target and the follow‐up efforts that identified additional inhibitors, along with findings from mode‐of‐action studies, are discussed.
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Affiliation(s)
| | | | | | | | | | - David R. Langley
- Department of Computer‐Assisted Drug Design Bristol‐Myers Squibb Research and Development, 5 Research Parkway, Wallingford, CT 06492 USA
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75
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The molecular and structural basis of advanced antiviral therapy for hepatitis C virus infection. Nat Rev Microbiol 2013; 11:482-96. [PMID: 23748342 DOI: 10.1038/nrmicro3046] [Citation(s) in RCA: 276] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The availability of the first molecular clone of the hepatitis C virus (HCV) genome allowed the identification and biochemical characterization of two viral enzymes that are targets for antiviral therapy: the protease NS3-4A and the RNA-dependent RNA polymerase NS5B. With the advent of cell culture systems that can recapitulate either the intracellular steps of the viral replication cycle or the complete cycle, additional drug targets have been identified, most notably the phosphoprotein NS5A, but also host cell factors that promote viral replication, such as cyclophilin A. Here, we review insights into the structures of these proteins and the mechanisms by which they contribute to the HCV replication cycle, and discuss how these insights have facilitated the development of new, directly acting antiviral compounds that have started to enter the clinic.
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76
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Yang D, Xue B, Wang X, Yu X, Liu N, Gao Y, Liu C, Zhu H. 2-octynoic acid inhibits hepatitis C virus infection through activation of AMP-activated protein kinase. PLoS One 2013; 8:e64932. [PMID: 23741428 PMCID: PMC3669134 DOI: 10.1371/journal.pone.0064932] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 04/19/2013] [Indexed: 12/23/2022] Open
Abstract
Many chronic hepatitis C virus (HCV)-infected patients with current therapy do not clear the virus. It is necessary to find novel treatments. The effect of 2-octynoic acid (2-OA) on HCV infection in human hepatocytes was examined. The mechanism of 2-OA antiviral activity was explored. Our data showed that 2-OA abrogated lipid accumulation in HCV replicon cells and virus-infected hepatocytes. It suppressed HCV RNA replication and infectious virus production with no cytotoxicity to the host cells. 2-OA did not affect hepatitis B virus replication in HepG2.2.15 cells derived from HepG2 cells transfected with full genome of HBV. Further study demonstrated that 2-OA activated AMP-activated protein kinase (AMPK) and inhibited acetyl-CoA carboxylase in viral-infected cells. Compound C, a specific inhibitor of AMPK, inhibited AMPK activity and reversed the reduction of intracellular lipid accumulation and the antiviral effect of 2-OA. Knockdown of AMPK expression by RNA interference abolished the activation of AMPK by 2-OA and blocked 2-OA antiviral activity. Interestingly, 2-OA induced interferon-stimulated genes (ISGs) and inhibited microRNA-122 (miR-122) expression in virus-infected hepatocytes. MiR-122 overexpression reversed the antiviral effect of 2-OA. Furthermore, knockdown of AMPK expression reversed both the induction of ISGs and suppression of miR-122 by 2-OA, implying that activated AMPK induces the intracellular innate response through the induction of ISGs and inhibiting miR-122 expression. 2-OA inhibits HCV infection through regulation of innate immune response by activated AMPK. These findings reveal a novel mechanism by which active AMPK inhibits HCV infection. 2-OA and its derivatives hold promise for novel drug development for chronic hepatitis C.
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Affiliation(s)
- Darong Yang
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
- Research Center of Cancer Prevention and Treatment of Hunan University and Hunan Provincial Tumor Hospital, Translational Medicine Research Center of Liver Cancer, Hunan Provincial Tumor Hospital (Affiliated Tumor Hospital of Xiangya Medical School of Central South University), Changsha, Hunan Province, China
| | - Binbin Xue
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
| | - Xiaohong Wang
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
| | - Xiaoyan Yu
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
| | - Nianli Liu
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
- Research Center of Cancer Prevention and Treatment of Hunan University and Hunan Provincial Tumor Hospital, Translational Medicine Research Center of Liver Cancer, Hunan Provincial Tumor Hospital (Affiliated Tumor Hospital of Xiangya Medical School of Central South University), Changsha, Hunan Province, China
| | - Yimin Gao
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
| | - Chen Liu
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida, United States of America
| | - Haizhen Zhu
- Department of Molecular Medicine of College of Biology, State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha, Hunan Province, China
- Research Center of Cancer Prevention and Treatment of Hunan University and Hunan Provincial Tumor Hospital, Translational Medicine Research Center of Liver Cancer, Hunan Provincial Tumor Hospital (Affiliated Tumor Hospital of Xiangya Medical School of Central South University), Changsha, Hunan Province, China
- * E-mail:
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Modeling shows that the NS5A inhibitor daclatasvir has two modes of action and yields a shorter estimate of the hepatitis C virus half-life. Proc Natl Acad Sci U S A 2013; 110:3991-6. [PMID: 23431163 DOI: 10.1073/pnas.1203110110] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The nonstructural 5A (NS5A) protein is a target for drug development against hepatitis C virus (HCV). Interestingly, the NS5A inhibitor daclatasvir (BMS-790052) caused a decrease in serum HCV RNA levels by about two orders of magnitude within 6 h of administration. However, NS5A has no known enzymatic functions, making it difficult to understand daclatasvir's mode of action (MOA) and to estimate its antiviral effectiveness. Modeling viral kinetics during therapy has provided important insights into the MOA and effectiveness of a variety of anti-HCV agents. Here, we show that understanding the effects of daclatasvir in vivo requires a multiscale model that incorporates drug effects on the HCV intracellular lifecycle, and we validated this approach with in vitro HCV infection experiments. The model predicts that daclatasvir efficiently blocks two distinct stages of the viral lifecycle, namely viral RNA synthesis and virion assembly/secretion with mean effectiveness of 99% and 99.8%, respectively, and yields a more precise estimate of the serum HCV half-life, 45 min, i.e., around four times shorter than previous estimates. Intracellular HCV RNA in HCV-infected cells treated with daclatasvir and the HCV polymerase inhibitor NM107 showed a similar pattern of decline. However, daclatasvir treatment led to an immediate and rapid decline of extracellular HCV titers compared to a delayed (6-9 h) and slower decline with NM107, confirming an effect of daclatasvir on both viral replication and assembly/secretion. The multiscale modeling approach, validated with in vitro kinetic experiments, brings a unique conceptual framework for understanding the mechanism of action of a variety of agents in development for the treatment of HCV.
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Abstract
Resolution of the three-dimensional structures of several Hepatitis C virus (HCV) proteins, together with the development of replicative cell culture systems, has led to the identification of a number of potential targets for direct-acting antiviral agents (DAA). Numerous families of drugs that potently inhibit the HCV life cycle in vitro have been identified, and some of these molecules have reached early to late clinical development. Two NS3-4A protease inhibitors, telaprevir and boceprevir, were approved in Europe and the United States in 2011 in combination with pegylated interferon (IFN)-α and ribavirin for the treatment of chronic hepatitis C related to HCV genotype 1. A number of other DAAs are at the clinical developmental stage in combination with pegylated IFN-α and ribavirin or with other DAAs in IFN-free regimens, with or without ribavirin. They include second-wave, first-generation, and second-generation NS3-4A protease inhibitors, nucleoside/nucleotide analogue inhibitors, and non-nucleoside inhibitors of HCV RNA-dependent RNA polymerase, inhibitors of nonstructural protein 5A and host-targeted agents, such as cyclophilin A inhibitors and microRNA-122 antagonists. The proof of concept that IFN-free regimens can lead to HCV eradication has recently been brought. This chapter provides an overview of the current treatment of HCV infection and discusses the future of HCV therapy with new anti-HCV drugs.
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Affiliation(s)
- Jean-Michel Pawlotsky
- Department of Virology, Hôpital Henri Mondor, Université Paris-Est, Créteil, France.
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80
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Delang L, Neyts J, Vliegen I, Abrignani S, Neddermann P, De Francesco R. Hepatitis C Virus-Specific Directly Acting Antiviral Drugs. Curr Top Microbiol Immunol 2013; 369:289-320. [DOI: 10.1007/978-3-642-27340-7_12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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81
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Resistance studies of a dithiazol analogue, DBPR110, as a potential hepatitis C virus NS5A inhibitor in replicon systems. Antimicrob Agents Chemother 2012; 57:723-33. [PMID: 23165461 DOI: 10.1128/aac.01403-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Hepatitis C virus (HCV), a member of the Flaviviridae family, affects approximately 3% of the world's population and is becoming the leading cause of liver disease in the world. Therefore, the development of novel or more effective treatment strategies to treat chronic HCV infection is urgently needed. In our previous study, we identified a potential HCV NS5A inhibitor, BP008. After further systemic optimization, we discovered a more potent HCV inhibitor, DBPR110. DBPR110 reduced the reporter expression of the HCV1b replicon with a 50% effective concentration (EC(50)) and a selective index value of 3.9 ± 0.9 pM and >12,800,000, respectively. DBPR110 reduced HCV2a replicon activity with an EC(50) and a selective index value of 228.8 ± 98.4 pM and >173,130, respectively. Sequencing analyses of several individual clones derived from the DBPR110-resistant RNAs purified from cells harboring genotype 1b and 2a HCV replicons revealed that amino acid substitutions mainly within the N-terminal region (domain I) of NS5A were associated with decreased inhibitor susceptibility. P58L/T and Y93H/N in genotype 1b and T24A, P58L, and Y93H in the genotype 2a replicon were the key substitutions for resistance selection. In the 1b replicon, V153M, M202L, and M265V play a compensatory role in replication and drug resistance. Moreover, DBPR110 displayed synergistic effects with alpha interferon (IFN-α), an NS3 protease inhibitor, and an NS5B polymerase inhibitor. In summary, our results present an effective small-molecule inhibitor, DBPR110, that potentially targets HCV NS5A. DBPR110 could be part of a more effective therapeutic strategy for HCV in the future.
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82
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Current world literature. Curr Opin Organ Transplant 2012; 17:688-99. [PMID: 23147911 DOI: 10.1097/mot.0b013e32835af316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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83
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In vitro activity of daclatasvir on hepatitis C virus genotype 3 NS5A. Antimicrob Agents Chemother 2012; 57:611-3. [PMID: 23089758 DOI: 10.1128/aac.01874-12] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The NS5A replication complex inhibitor daclatasvir (DCV; BMS-790052) inhibits hybrid replicons containing hepatitis C virus (HCV) genotype 3a (HCV3a) NS5A genes with 50% effective concentrations (EC(50)s) ranging from 120 to 870 pM. Selection studies with a hybrid HCV3a replicon identified NS5A residues 31 and 93 as sites for DCV-selected resistance. Our results support the potential use of DCV as a component in combination therapies for HCV3a chronic infection.
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84
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Small molecule inhibitors of the hepatitis C virus-encoded NS5A protein. Virus Res 2012; 170:1-14. [PMID: 23009750 DOI: 10.1016/j.virusres.2012.09.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 09/13/2012] [Accepted: 09/13/2012] [Indexed: 12/20/2022]
Abstract
Hepatitis C virus (HCV) is a modern-day pandemic; 2-3% of the world's population are thought to be infected with the virus and are subsequently at risk of developing end-stage liver diseases. The traditional standard of care (SOC) for HCV-infected patients has been limited to a regimen of pegylated-interferon alpha (pegIFN) and ribavirin; displaying low cure rates in a majority of patients and severe side effects. However, in 2011 the first direct-acting antivirals (DAA) were licensed to treat HCV-infected patients in combination with SOC, which served to elevate treatment response rates. The HCV drug development pipeline is currently populated with many additional and improved DAAs; primarily molecules that target the virus-encoded protease or polymerase enzymes. These molecules are being evaluated both in combination with the traditional SOC and together with other DAAs as all-oral pegIFN-free regimens with the ultimate goal of developing multiple DAA-containing HCV therapies that do not rely on an pegIFN backbone. A recent addition to the arsenal of HCV inhibitors in development is represented by an entirely new DAA class; molecules that target the HCV-encoded non-enzymatic NS5A protein. NS5A is essential for HCV propagation and, although its actual functions are largely unknown, it is likely a key regulator of viral genome replication and virion assembly. The protein is exquisitely sensitive to small molecule-mediated inhibition; NS5A-targeting molecules are probably the most potent antiviral molecules ever discovered and exhibit a number of other attractive drug-like properties, including activity against many HCV genotypes/subtypes and once-daily dosing potential. Although their mechanism of action is unclear, NS5A-targeting molecules are already proving their utility in clinical evaluation; particularly as components of pegIFN-sparring DAA combination regimens. This review will aim to amalgamate our current understanding and knowledge of NS5A-targeting molecules; their discovery, properties, applications, and insight into their future impact as components of all-oral pegIFN-free DAA combination therapies to combat HCV infection.
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85
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Suppression of viral RNA binding and the assembly of infectious hepatitis C virus particles in vitro by cyclophilin inhibitors. J Virol 2012; 86:12616-24. [PMID: 22973029 DOI: 10.1128/jvi.01351-12] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Nonstructural protein 5A (NS5A) of hepatitis C virus (HCV) is an indispensable component of the HCV replication and assembly machineries. Although its precise mechanism of action is not yet clear, current evidence indicates that its structure and function are regulated by the cellular peptidylprolyl isomerase cyclophilin A (CyPA). CyPA binds to proline residues in the C-terminal half of NS5A, in a distributed fashion, and modulates the structure of the disordered domains II and III. Cyclophilin inhibitors (CPIs), including cyclosporine (CsA) and its nonimmunosuppressive derivatives, inhibit HCV infection of diverse genotypes, both in vitro and in vivo. Here we report a mechanism by which CPIs inhibit HCV infection and demonstrate that CPIs can suppress HCV assembly in addition to their well-documented inhibitory effect on RNA replication. Although the interaction between NS5A and other viral proteins is not affected by CPIs, RNA binding by NS5A in cell culture-based HCV (HCVcc)-infected cells is significantly inhibited by CPI treatment, and sensitivity of RNA binding is correlated with previously characterized CyPA dependence or CsA sensitivity of HCV mutants. Furthermore, the difference in CyPA dependence between a subgenomic and a full-length replicon of JFH-1 was due, at least in part, to an additional role that CyPA plays in HCV assembly, a conclusion that is supported by experiments with the clinical CPI alisporivir. The host-directed nature and the ability to interfere with more than one step in the HCV life cycle may result in a higher genetic barrier to resistance for this class of HCV inhibitors.
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86
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Lim PJ, Chatterji U, Cordek D, Sharma SD, Garcia-Rivera JA, Cameron CE, Lin K, Targett-Adams P, Gallay PA. Correlation between NS5A dimerization and hepatitis C virus replication. J Biol Chem 2012; 287:30861-73. [PMID: 22801423 DOI: 10.1074/jbc.m112.376822] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hepatitis C virus (HCV) is the main agent of acute and chronic liver diseases leading to cirrhosis and hepatocellular carcinoma. The current standard therapy has limited efficacy and serious side effects. Thus, the development of alternate therapies is of tremendous importance. HCV NS5A (nonstructural 5A protein) is a pleiotropic protein with key roles in HCV replication and cellular signaling pathways. Here we demonstrate that NS5A dimerization occurs through Domain I (amino acids 1-240). This interaction is not mediated by nucleic acids because benzonase, RNase, and DNase treatments do not prevent NS5A-NS5A interactions. Importantly, DTT abrogates NS5A-NS5A interactions but does not affect NS5A-cyclophilin A interactions. Other reducing agents such as tris(2-carboxyethyl)phosphine and 2-mercaptoethanol also abrogate NS5A-NS5A interactions, implying that disulfide bridges may play a role in this interaction. Cyclophilin inhibitors, cyclosporine A, and alisporivir and NS5A inhibitor BMS-790052 do not block NS5A dimerization, suggesting that their antiviral effects do not involve the disruption of NS5A-NS5A interactions. Four cysteines, Cys-39, Cys-57, Cys-59, and Cys-80, are critical for dimerization. Interestingly, the four cysteines have been proposed to form a zinc-binding motif. Supporting this notion, NS5A dimerization is greatly facilitated by Zn(2+) but not by Mg(2+) or Mn(2+). Importantly, the four cysteines are vital not only for viral replication but also critical for NS5A binding to RNA, revealing a correlation between NS5A dimerization, RNA binding, and HCV replication. Altogether our data suggest that NS5A-NS5A dimerization and/or multimerization could represent a novel target for the development of HCV therapies.
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87
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Lawitz EJ, Gruener D, Hill JM, Marbury T, Moorehead L, Mathias A, Cheng G, Link JO, Wong KA, Mo H, McHutchison JG, Brainard DM. A phase 1, randomized, placebo-controlled, 3-day, dose-ranging study of GS-5885, an NS5A inhibitor, in patients with genotype 1 hepatitis C. J Hepatol 2012; 57:24-31. [PMID: 22314425 DOI: 10.1016/j.jhep.2011.12.029] [Citation(s) in RCA: 140] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Revised: 12/20/2011] [Accepted: 12/29/2011] [Indexed: 12/31/2022]
Abstract
BACKGROUND & AIMS GS-5885 is an inhibitor of the hepatitis C virus (HCV) NS5A protein and exhibits potent suppression of genotype 1 HCV replicons. The safety, tolerability, pharmacokinetics, antiviral activity, and resistance profile of once-daily GS-5885 doses of 1-90 mg were evaluated in patients with chronic genotype 1 HCV. METHODS Genotype 1 HCV-infected patients were randomized to 3 days of once-daily (QD) dosing with placebo (n=12) or GS-5885 1 mg (n=10), 3 mg (n=10), 10 mg (n=20), 30 mg (n=10), or 90 mg (n=10). Plasma samples for pharmacokinetics, HCV RNA, and NS5A sequencing were collected through day 14. RESULTS GS-5885 was well tolerated and resulted in median maximal reductions in HCV RNA ranging from 2.3 log(10) IU/ml (1 mg QD) to 3.3 log(10) IU/ml (10 mg QD in genotype 1b and 30 mg QD). E(max) modeling indicated GS-5885 30 mg was associated with>95% of maximal antiviral response to HCV genotype 1a. HCV RNA reductions were generally more sustained among patients with genotype 1b vs. 1a. Three of 60 patients had a reduced response and harbored NS5A-resistant virus at baseline. NS5A sequencing identified residues 30 and 31 in genotype 1a, and 93 in genotype 1b as the predominant sites of mutation following GS-5885 dosing. Plasma pharmacokinetics was consistent with QD dosing. CONCLUSIONS During 3 days of monotherapy, low doses of GS-5885 demonstrated significant antiviral activity in genotype 1a and 1b HCV-infected patients. GS-5885 is currently being evaluated in combination with direct antiviral regimens with and without peginterferon.
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88
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Role for TBC1D20 and Rab1 in hepatitis C virus replication via interaction with lipid droplet-bound nonstructural protein 5A. J Virol 2012; 86:6491-502. [PMID: 22491470 DOI: 10.1128/jvi.00496-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Replication and assembly of hepatitis C virus (HCV) depend on the host's secretory and lipid-biosynthetic machinery. Viral replication occurs on endoplasmic reticulum (ER)-derived modified membranes, while viral assembly is thought to occur on lipid droplets (LDs). A physical association and coordination between the viral replication and assembly complexes are prerequisites for efficient viral production. Nonstructural protein 5A (NS5A), which localizes both to the ER and LDs, is an ideal candidate for this function. Here, the interaction of NS5A with host cell membranes and binding partners was characterized in living cells. The binding of NS5A to LDs is apparently irreversible, both in HCV-infected cells and when ectopically expressed. In HCV-infected cells, NS5A fluorescence was observed around the LDs and in perinuclear structures that were incorporated into a highly immobile platform superimposed over the ER membrane. Moreover, TBC1D20 and its cognate GTPase Rab1 are recruited by NS5A to LDs. The NS5A-TBC1D20 interaction was shown to be essential for the viral life cycle. In cells, expression of the Rab1 dominant negative (Rab1DN) GTPase mutant abolished steady-state LDs. In infected cells, Rab1DN induced the elimination of NS5A from viral replication sites. Our results demonstrate the significance of the localization of NS5A to LDs and support a model whereby its interaction with TBC1D20 and Rab1 affects lipid droplet metabolism to promote the viral life cycle.
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89
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Yang PL, Gao M, Lin K, Liu Q, Villareal VA. Anti-HCV drugs in the pipeline. Curr Opin Virol 2011; 1:607-16. [PMID: 22440918 DOI: 10.1016/j.coviro.2011.10.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 10/18/2011] [Accepted: 10/19/2011] [Indexed: 02/08/2023]
Abstract
Several directly acting and host targeting antivirals that inhibit hepatitis C virus replication have entered clinical trials. Among the most advanced of these are RG7128, an inhibitor of the NS5B polymerase; BMS-790052, an inhibitor of NS5A; and alisporivir, an inhibitor of human cyclophilins. These agents have potent antiviral activity in chronic HCV patients, act additively or synergistically with inhibitors of the HCV NS3/4A protease, and improve the rate of virologic response produced by traditional pegylated interferon plus ribavirin therapy. No cross resistance has been observed; moreover, nucleoside NS5B and cyclophilin inhibitors appear to suppress resistance to non-nucleoside NS5B and NS3/4A inhibitors. Several recent reports of virologic responses produced by combinations of agents that inhibit HCV replication in the absence of interferon provide optimism that eradication of HCV will be possible without interferon in the future.
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Affiliation(s)
- Priscilla L Yang
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, United States.
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90
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Popescu CI, Rouillé Y, Dubuisson J. Hepatitis C virus assembly imaging. Viruses 2011; 3:2238-54. [PMID: 22163343 PMCID: PMC3230850 DOI: 10.3390/v3112238] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/03/2011] [Accepted: 11/04/2011] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C Virus (HCV) assembly process is the least understood step in the virus life cycle. The functional data revealed by forward and reverse genetics indicated that both structural and non-structural proteins are involved in the assembly process. Using confocal and electron microscopy different groups determined the subcellular localization of different viral proteins and they identified the lipid droplets (LDs) as the potential viral assembly site. Here, we aim to review the mechanisms that govern the viral proteins recruitment to LDs and discuss the current model of HCV assembly process. Based on previous examples, this review will also discuss advanced imaging techniques as potential means to extend our present knowledge of HCV assembly process.
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Affiliation(s)
- Costin-Ioan Popescu
- Institute of Biochemistry, The Romanian Academy, Splaiul Independentei 296, 060031 Bucharest 17, Romania
| | - Yves Rouillé
- Inserm U1019, CNRS UMR8204, Center for Infection and Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille 59021, France; E-Mails: (Y.R.); (J.D.)
| | - Jean Dubuisson
- Inserm U1019, CNRS UMR8204, Center for Infection and Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille 59021, France; E-Mails: (Y.R.); (J.D.)
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91
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Resistance analysis and characterization of a thiazole analogue, BP008, as a potent hepatitis C virus NS5A inhibitor. Antimicrob Agents Chemother 2011; 56:44-53. [PMID: 22006008 DOI: 10.1128/aac.00599-11] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Hepatitis C virus (HCV) is a global health problem, affecting approximately 3% of the world's population. The standard treatment for HCV infection is often poorly tolerated and ineffective. Therefore, the development of novel or more effective treatment strategies to treat chronic HCV infection is urgently needed. In this report, BP008, a potent small-molecule inhibitor of HCV replication, was developed from a class of compounds with thiazol core structures by means of utilizing a cell-based HCV replicon system. The compound reduced the reporter expression of the HCV1b replicon with a 50% effective concentration (EC(50)) and selective index value of 4.1 ± 0.7 nM and >12,195, respectively. Sequencing analyses of several individual clones derived from BP008-resistant RNAs purified from cells harboring HCV1b replicon revealed that amino acid substitutions mainly within the N-terminal region (domain I) of NS5A were associated with decreased inhibitor susceptibility. Q24L, P58S, and Y93H are the key substitutions for resistance selection; F149L and V153M play the compensatory role in the replication and drug resistance processes. Moreover, BP008 displayed synergistic effects with alpha interferon (IFN-α), NS3 protease inhibitor, and NS5B polymerase inhibitor, as well as good oral bioavailability in SD rats and favorable exposure in rat liver. In summary, our results pointed to an effective small-molecule inhibitor, BP008, that potentially targets HCV NS5A. BP008 can be considered a part of a more effective therapeutic strategy for HCV in the future.
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92
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Lee C. Discovery of hepatitis C virus NS5A inhibitors as a new class of anti-HCV therapy. Arch Pharm Res 2011; 34:1403-7. [DOI: 10.1007/s12272-011-0921-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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93
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Cordek DG, Bechtel JT, Maynard AT, Kazmierski WM, Cameron CE. TARGETING THE NS5A PROTEIN OF HCV: AN EMERGING OPTION. DRUG FUTURE 2011; 36:691-711. [PMID: 23378700 PMCID: PMC3558953 DOI: 10.1358/dof.2011.036.09.1641618] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Hepatitis C virus (HCV) infects more than 3% of the world's population, leading to an increased risk of cirrhosis and hepatocellular carcinoma. The current standard of care, a combination of pegylated interferon alfa and ribavirin, is poorly tolerated and often ineffective against the most prevalent genotype of the virus, genotype 1. The very recent approval of boceprevir and telaprevir, two HCV protease inhibitors, promises to significantly improve treatment options and outcomes. In addition to the viral protease NS3 and the viral polymerase NS5B, direct-acting antivirals are now in development against NS5A. A multifunctional phosphoprotein, NS5A is essential to HCV genome replication, but has no known enzymatic function. Here we report how the design of small-molecule inhibitors against NS5A has evolved from promising monomers to highly potent dimeric compounds effective against many HCV genotypes. We also highlight recent clinical data and how the inhibitors may bind to NS5A, itself capable of forming dimers.
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Affiliation(s)
- D G Cordek
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
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94
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Qiu D, Lemm JA, O'Boyle DR, Sun JH, Nower PT, Nguyen V, Hamann LG, Snyder LB, Deon DH, Ruediger E, Meanwell NA, Belema M, Gao M, Fridell RA. The effects of NS5A inhibitors on NS5A phosphorylation, polyprotein processing and localization. J Gen Virol 2011; 92:2502-2511. [PMID: 21795470 DOI: 10.1099/vir.0.034801-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hepatitis C virus (HCV) non-structural protein 5A (NS5A) is a multi-functional protein that is expressed in basally phosphorylated (p56) and in hyperphosphorylated (p58) forms. NS5A phosphorylation has been implicated in regulating multiple aspects of HCV replication. We recently reported the identification of a class of compounds that potently inhibit HCV RNA replication by targeting NS5A. Although the precise mechanism of inhibition of these compounds is not well understood, one activity that has been described is their ability to block expression of the hyperphosphorylated form of NS5A. Here, we report that an NS5A inhibitor impaired hyperphosphorylation without affecting basal phosphorylation at the C-terminal region of NS5A. This inhibitor activity did not require NS5A domains II and III and was distinct from that of a cellular kinase inhibitor that also blocked NS5A hyperphosphorylation, results that are consistent with an inhibitor-binding site within the N-terminal region of NS5A. In addition, we observed that an NS5A inhibitor promoted the accumulation of an HCV polyprotein intermediate, suggesting that inhibitor binding to NS5A may occur prior to the completion of polyprotein processing. Finally, we observed that NS5A p56 and p58 separated into different membrane fractions during discontinuous sucrose gradient centrifugation, consistent with these NS5A phosphoforms performing distinct replication functions. The p58 localization pattern was disrupted by an NS5A inhibitor. Collectively, our results suggest that NS5A inhibitors probably impact several aspects of HCV expression and regulation. These findings may help to explain the exceptional potency of this class of HCV replication complex inhibitors.
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Affiliation(s)
- Dike Qiu
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Julie A Lemm
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Donald R O'Boyle
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Jin-Hua Sun
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Peter T Nower
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Van Nguyen
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Lawrence G Hamann
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Lawrence B Snyder
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Daniel H Deon
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Edward Ruediger
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Nicholas A Meanwell
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Makonen Belema
- Medicinal Chemistry, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Min Gao
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Robert A Fridell
- Department of Virology, Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
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Mechanistic characterization of GS-9190 (Tegobuvir), a novel nonnucleoside inhibitor of hepatitis C virus NS5B polymerase. Antimicrob Agents Chemother 2011; 55:4196-203. [PMID: 21746939 DOI: 10.1128/aac.00307-11] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
GS-9190 (Tegobuvir) is a novel imidazopyridine inhibitor of hepatitis C virus (HCV) RNA replication in vitro and has demonstrated potent antiviral activity in patients chronically infected with genotype 1 (GT1) HCV. GS-9190 exhibits reduced activity against GT2a (JFH1) subgenomic replicons and GT2a (J6/JFH1) infectious virus, suggesting that the compound's mechanism of action involves a genotype-specific viral component. To further investigate the GS-9190 mechanism of action, we utilized the susceptibility differences between GT1b and GT2a by constructing a series of replicon chimeras where combinations of 1b and 2a nonstructural proteins were encoded within the same replicon. The antiviral activities of GS-9190 against the chimeric replicons were reduced to levels comparable to that of the wild-type GT2a replicon in chimeras expressing GT2a NS5B. GT1b replicons in which the β-hairpin region (amino acids 435 to 455) was replaced by the corresponding sequence of GT2a were markedly less susceptible to GS-9190, indicating the importance of the thumb subdomain of the polymerase in this effect. Resistance selection in GT1b replicon cells identified several mutations in NS5B (C316Y, Y448H, Y452H, and C445F) that contributed to the drug resistance phenotype. Reintroduction of these mutations into wild-type replicons conferred resistance to GS-9190, with the number of NS5B mutations correlating with the degree of resistance. Analysis of GS-9190 cross-resistance against previously reported NS5B drug-selected mutations showed that the resistance pattern of GS-9190 is different from other nonnucleoside inhibitors. Collectively, these data demonstrate that GS-9190 represents a novel class of nonnucleoside polymerase inhibitors that interact with NS5B likely through involvement of the β-hairpin in the thumb subdomain.
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