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Shannon A, Canard B. Kill or corrupt: Mechanisms of action and drug-resistance of nucleotide analogues against SARS-CoV-2. Antiviral Res 2023; 210:105501. [PMID: 36567022 PMCID: PMC9773703 DOI: 10.1016/j.antiviral.2022.105501] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
Nucleoside/tide analogues (NAs) have long been used in the fight against viral diseases, and now present a promising option for the treatment of COVID-19. Once activated to the 5'-triphosphate state, NAs act by targeting the viral RNA-dependent RNA-polymerase for incorporation into the viral RNA genome. Incorporated analogues can either 'kill' (terminate) synthesis, or 'corrupt' (genetically or chemically) the RNA. Against coronaviruses, the use of NAs has been further complicated by the presence of a virally encoded exonuclease domain (nsp14) with proofreading and repair capacities. Here, we describe the mechanism of action of four promising anti-COVID-19 NAs; remdesivir, molnupiravir, favipiravir and bemnifosbuvir. Their distinct mechanisms of action best exemplify the concept of 'killers' and 'corruptors'. We review available data regarding their ability to be incorporated and excised, and discuss the specific structural features that dictate their overall potency, toxicity, and mutagenic potential. This should guide the synthesis of novel analogues, lend insight into the potential for resistance mutations, and provide a rational basis for upcoming combinations therapies.
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Affiliation(s)
- Ashleigh Shannon
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille, Cedex 09, France
| | - Bruno Canard
- AFMB, CNRS, Aix-Marseille University, UMR 7257, Case 925, 163 Avenue de Luminy, 13288, Marseille, Cedex 09, France.
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2
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Inhibition of Viral RNA-Dependent RNA Polymerases by Nucleoside Inhibitors: An Illustration of the Unity and Diversity of Mechanisms. Int J Mol Sci 2022; 23:ijms232012649. [PMID: 36293509 PMCID: PMC9604226 DOI: 10.3390/ijms232012649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022] Open
Abstract
RNA-dependent RNA polymerase (RdRP) is essential for the replication and expression of RNA viral genomes. This class of viruses comprise a large number of highly pathogenic agents that infect essentially all species of plants and animals including humans. Infections often lead to epidemics and pandemics that have remained largely out of control due to the lack of specific and reliable preventive and therapeutic regimens. This unmet medical need has led to the exploration of new antiviral targets, of which RdRP is a major one, due to the fact of its obligatory need in virus growth. Recent studies have demonstrated the ability of several synthetic nucleoside analogs to serve as mimics of the corresponding natural nucleosides. These mimics cause stalling/termination of RdRP, or misincorporation, preventing virus replication or promoting large-scale lethal mutations. Several such analogs have received clinical approval and are being routinely used in therapy. In parallel, the molecular structural basis of their inhibitory interactions with RdRP is being elucidated, revealing both traditional and novel mechanisms including a delayed chain termination effect. This review offers a molecular commentary on these mechanisms along with their clinical implications based on analyses of recent results, which should facilitate the rational design of structure-based antiviral drugs.
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3
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Long C, Romero ME, La Rocco D, Yu J. Dissecting nucleotide selectivity in viral RNA polymerases. Comput Struct Biotechnol J 2021; 19:3339-3348. [PMID: 34104356 PMCID: PMC8175102 DOI: 10.1016/j.csbj.2021.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 01/18/2023] Open
Abstract
Designing antiviral therapeutics is of great concern per current pandemics caused by novel coronavirus or SARS-CoV-2. The core polymerase enzyme in the viral replication/transcription machinery is generally conserved and serves well for drug target. In this work we briefly review structural biology and computational clues on representative single-subunit viral polymerases that are more or less connected with SARS-CoV-2 RNA dependent RNA polymerase (RdRp), in particular, to elucidate how nucleotide substrates and potential drug analogs are selected in the viral genome synthesis. To do that, we first survey two well studied RdRps from Polio virus and hepatitis C virus in regard to structural motifs and key residues that have been identified for the nucleotide selectivity. Then we focus on related structural and biochemical characteristics discovered for the SARS-CoV-2 RdRp. To further compare, we summarize what we have learned computationally from phage T7 RNA polymerase (RNAP) on its stepwise nucleotide selectivity, and extend discussion to a structurally similar human mitochondria RNAP, which deserves special attention as it cannot be adversely affected by antiviral treatments. We also include viral phi29 DNA polymerase for comparison, which has both helicase and proofreading activities on top of nucleotide selectivity for replication fidelity control. The helicase and proofreading functions are achieved by protein components in addition to RdRp in the coronavirus replication-transcription machine, with the proofreading strategy important for the fidelity control in synthesizing a comparatively large viral genome.
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Affiliation(s)
- Chunhong Long
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
| | | | - Daniel La Rocco
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Jin Yu
- Department of Physics and Astronomy, Department of Chemistry, NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, CA 92697, USA
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El-Sokkary MMA, Gotina L, Al-Sanea MM, Pae AN, Elbargisy RM. Molecular Characterization of Hepatitis C Virus for Developed Antiviral Agents Resistance Mutations and New Insights into in-silico Prediction Studies. Infect Drug Resist 2020; 13:4235-4248. [PMID: 33262618 PMCID: PMC7696641 DOI: 10.2147/idr.s267809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/24/2020] [Indexed: 02/05/2023] Open
Abstract
Background Identification and characterization of developed antiviral drug resistance mutations are key to the success of antiviral therapies against hepatitis C virus (HCV), which remains a worldwide highly prevalent pathogenic disease. Although most studies focus on HCV genotypes 1, 2 or 3, the investigation of drug resistance in HCV genotype 4, predominant in North Africa, is especially significant in Egypt. Methods We performed mutational and genotypic analysis of the untranslated region (UTR) and nonstructural protein 5B (NS5B) drug resistance-associated regions of HCV for patients in the surrounding villages of Mansoura city, who were not responding to different antiviral treatments (sofosbuvir (SOF), ribavirin, and interferon). Furthermore, molecular modelling approaches (homology modelling and docking studies) were used to investigate the significance of the identified NS5B mutations for SOF and ribavirin binding in the HCV genotype 4a NS5B active site. Results Genotypic analysis confirmed all samples to have genotype 4 with sub-genotype 4a predominant. Partial sequencing of the UTR and NS5B resistance-associated regions identified D258E, T282S and A307G mutations in all isolates of NS5B. The UTR mutation site at position 243 was associated with interferon resistance, whereas the NS5B T282S mutation was considered as significant for SOF and ribavirin resistance. Docking studies in the HCV genotype 4a homology model predict SOF and ribavirin to accommodate a nucleotide-like binding mode, in which the T282 residue does interfere with the binding as it would in HCV genotypes 1 and 2. Mutation energy calculations predict T282S to moderately destabilize the binding of SOF and ribavirin by 0.57 and 0.47 kcal/mol, respectively. Conclusion The performed study identified and characterized several antiviral drug resistance mutations of HCV genotype 4a and proposed a mechanism by which the T282S mutation may contribute to SOF and ribavirin resistance.
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Affiliation(s)
- Mohamed M Adel El-Sokkary
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Lizaveta Gotina
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 02792, Republic of Korea.,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Daejeon, Korea
| | - Mohammad M Al-Sanea
- Department of Pharmaceutical Chemistry, College of Pharmacy, Jouf University, Sakaka, Al-Jouf, Saudi Arabia
| | - Ae Nim Pae
- Convergence Research Center for Diagnosis, Treatment and Care System of Dementia, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 02792, Republic of Korea.,Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Daejeon, Korea
| | - Rehab Mohammed Elbargisy
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt.,Department of Pharmaceutics, College of Pharmacy, Jouf University, Sakaka, Al-Jouf, Saudi Arabia
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5
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Ju J, Li X, Kumar S, Jockusch S, Chien M, Tao C, Morozova I, Kalachikov S, Kirchdoerfer RN, Russo JJ. Nucleotide analogues as inhibitors of SARS-CoV Polymerase. Pharmacol Res Perspect 2020; 8:e00674. [PMID: 33124786 PMCID: PMC7596664 DOI: 10.1002/prp2.674] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/14/2020] [Accepted: 09/21/2020] [Indexed: 01/18/2023] Open
Abstract
SARS-CoV-2, a member of the coronavirus family, has caused a global public health emergency. Based on our analysis of hepatitis C virus and coronavirus replication, and the molecular structures and activities of viral inhibitors, we previously reasoned that the FDA-approved hepatitis C drug EPCLUSA (Sofosbuvir/Velpatasvir) should inhibit coronaviruses, including SARS-CoV-2. Here, using model polymerase extension experiments, we demonstrate that the active triphosphate form of Sofosbuvir is incorporated by low-fidelity polymerases and SARS-CoV RNA-dependent RNA polymerase (RdRp), and blocks further incorporation by these polymerases; the active triphosphate form of Sofosbuvir is not incorporated by a host-like high-fidelity DNA polymerase. Using the same molecular insight, we selected 3'-fluoro-3'-deoxythymidine triphosphate and 3'-azido-3'-deoxythymidine triphosphate, which are the active forms of two other anti-viral agents, Alovudine and AZT (an FDA-approved HIV/AIDS drug) for evaluation as inhibitors of SARS-CoV RdRp. We demonstrate the ability of two of these HIV reverse transcriptase inhibitors to be incorporated by SARS-CoV RdRp where they also terminate further polymerase extension. Given the 98% amino acid similarity of the SARS-CoV and SARS-CoV-2 RdRps, we expect these nucleotide analogues would also inhibit the SARS-CoV-2 polymerase. These results offer guidance to further modify these nucleotide analogues to generate more potent broad-spectrum anti-coronavirus agents.
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Affiliation(s)
- Jingyue Ju
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
- Department of Molecular Pharmacology and TherapeuticsColumbia UniversityNew YorkNYUSA
| | - Xiaoxu Li
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
| | - Shiv Kumar
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
| | - Steffen Jockusch
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of ChemistryColumbia UniversityNew YorkNYUSA
| | - Minchen Chien
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
| | - Chuanjuan Tao
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
| | - Irina Morozova
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
| | - Sergey Kalachikov
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
| | - Robert N. Kirchdoerfer
- Department of BiochemistryUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
- Institute of Molecular VirologyUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - James J. Russo
- Center for Genome Technology and Biomolecular EngineeringColumbia UniversityNew YorkNew YorkUSA
- Department of Chemical EngineeringColumbia UniversityNew YorkNYUSA
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Boehr AK, Arnold JJ, Oh HS, Cameron CE, Boehr DD. 2'-C-methylated nucleotides terminate virus RNA synthesis by preventing active site closure of the viral RNA-dependent RNA polymerase. J Biol Chem 2019; 294:16897-16907. [PMID: 31575662 PMCID: PMC6851289 DOI: 10.1074/jbc.ra119.010214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/28/2019] [Indexed: 01/25/2023] Open
Abstract
The 2'-C-methyl ribonucleosides are nucleoside analogs representing an important class of antiviral agents, especially against positive-strand RNA viruses. Their value is highlighted by the highly successful anti-hepatitis C drug sofosbuvir. When appropriately phosphorylated, these nucleotides are successfully incorporated into RNA by the virally encoded RNA-dependent RNA polymerase (RdRp). This activity prevents further RNA extension, but the mechanism is poorly characterized. Previously, we had identified NMR signatures characteristic of formation of RdRp-RNA binary and RdRp-RNA-NTP ternary complexes for the poliovirus RdRp, including an open-to-closed conformational change necessary to prepare the active site for catalysis of phosphoryl transfer. Here we used these observations as a framework for interpreting the effects of 2'-C-methyl adenosine analogs on RNA chain extension in solution-state NMR spectroscopy experiments, enabling us to gain additional mechanistic insights into 2'-C-methyl ribonucleoside-mediated RNA chain termination. Contrary to what has been proposed previously, poliovirus RdRp that was bound to RNA with an incorporated 2'-C-methyl nucleotide could still bind to the next incoming NTP. Our results also indicated that incorporation of the 2'-C-methyl nucleotide does not disrupt RdRp-RNA interactions and does not prevent translocation. Instead, incorporation of the 2'-C-methyl nucleotide blocked closure of the RdRp active site upon binding of the next correct incoming NTP, which prevented further nucleotide addition. We propose that other nucleotide analogs that act as nonobligate chain terminators may operate through a similar mechanism.
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Affiliation(s)
- Alyson K Boehr
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Jamie J Arnold
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Hyung S Oh
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - Craig E Cameron
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802
| | - David D Boehr
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802
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Jia H, Gong P. A Structure-Function Diversity Survey of the RNA-Dependent RNA Polymerases From the Positive-Strand RNA Viruses. Front Microbiol 2019; 10:1945. [PMID: 31507560 PMCID: PMC6713929 DOI: 10.3389/fmicb.2019.01945] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 08/07/2019] [Indexed: 01/15/2023] Open
Abstract
The RNA-dependent RNA polymerases (RdRPs) encoded by the RNA viruses are a unique class of nucleic acid polymerases. Each viral RdRP contains a 500–600 residue catalytic module with palm, fingers, and thumb domains forming an encircled human right hand architecture. Seven polymerase catalytic motifs are located in the RdRP palm and fingers domains, comprising the most conserved parts of the RdRP and are responsible for the RNA-only specificity in catalysis. Functional regions are often found fused to the RdRP catalytic module, resulting in a high level of diversity in RdRP global structure and regulatory mechanism. In this review, we surveyed all 46 RdRP-sequence available virus families of the positive-strand RNA viruses listed in the 2018b collection of the International Committee on Virus Taxonomy (ICTV) and chose a total of 49 RdRPs as representatives. By locating hallmark residues in RdRP catalytic motifs and by referencing structural and functional information in the literature, we were able to estimate the N- and C-terminal boundaries of the catalytic module in these RdRPs, which in turn serve as reference points to predict additional functional regions beyond the catalytic module. Interestingly, a large number of virus families may have additional regions fused to the RdRP N-terminus, while only a few of them have such regions on the C-terminal side of the RdRP. The current knowledge on these additional regions, either in three-dimensional (3D) structure or in function, is quite limited. In the five RdRP-structure available virus families in the positive-strand RNA viruses, only the Flaviviridae family has the 3D structural information resolved for such regions. Hence, future efforts to solve full-length RdRP structures containing these regions and to dissect the functional contribution of them are necessary to improve the overall understanding of the RdRP proteins as an evolutionarily integrated group, and our analyses here may serve as a guideline for selecting representative RdRP systems in these studies.
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Affiliation(s)
- Hengxia Jia
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Peng Gong
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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Han B, Martin R, Xu S, Parvangada A, Svarovskaia ES, Mo H, Dvory-Sobol H. Sofosbuvir susceptibility of genotype 1 to 6 HCV from DAA-naïve subjects. Antiviral Res 2019; 170:104574. [PMID: 31394118 DOI: 10.1016/j.antiviral.2019.104574] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 12/12/2022]
Abstract
High sequence diversity of HCV may lead to variation in susceptibility to antiviral agents amongst different genotypes and subtypes of the virus. We assessed the susceptibility to sofosbuvir of chimeric replicons carrying the full length NS5B coding region from 479 HCV infected, treatment-naïve patients, including 15 subtypes in 6 genotypes. NS5B replicon vectors with subtype 1b, subtype 4a and subtype 6a backbone were modified to support testing of patient samples. We also evaluated sofosbuvir susceptibility in a panel of 331 replicons containing engineered NS5B inhibitor resistance-associated substitutions. The mean 50% effective sofosbuvir concentration (EC50) amongst different genotypes ranged from 32 (subtype 2a) to 130 nM (genotype 4); while some variation in susceptibility amongst patient isolates was observed, the 95th percentile for any genotype did not exceed 189 nM. Levels of resistance to sofosbuvir in replicons containing S282T were between 2.4 and 18 fold-change in EC50; no other single NS5B resistance-associated substitution demonstrated reduced sofosbuvir susceptibility. These data suggest that S282T is the only known substitution that confers detectable resistance to sofosbuvir in vitro. Sofosbuvir displayed potent antiviral activity across a diverse range of NS5B mutants and HCV clinical isolates in multiple subtypes of genotypes 1 to 6.
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Affiliation(s)
- Bin Han
- Gilead Sciences, Foster City, CA, USA
| | | | - Simin Xu
- Gilead Sciences, Foster City, CA, USA
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9
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Sarrazin C, Cooper CL, Manns MP, Reddy KR, Kowdley KV, Roberts SK, Dvory-Sobol H, Svarovskia E, Martin R, Camus G, Doehle BP, Stamm LM, Hyland RH, Brainard DM, Mo H, Gordon SC, Bourliere M, Zeuzem S, Flamm SL. No impact of resistance-associated substitutions on the efficacy of sofosbuvir, velpatasvir, and voxilaprevir for 12 weeks in HCV DAA-experienced patients. J Hepatol 2018; 69:1221-1230. [PMID: 30098373 DOI: 10.1016/j.jhep.2018.07.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 07/20/2018] [Accepted: 07/30/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS In phase III studies, the fixed dose combination of sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX) administered for 12 weeks led to a sustained virologic response at 12 weeks (SVR12) in 96% of NS5A inhibitor-experienced patients, and an SVR12 rate of 98% in DAA-experienced patients who had not previously received an NS5A inhibitor. Herein, we evaluate the relationship between the presence of detectable resistance-associated substitutions (RASs) at baseline and treatment outcome, and whether RASs were selected for in cases of virologic failure. METHODS NS3, NS5A, and NS5B deep sequencing analyses were performed at baseline for all patients and at the time of virologic failure. Results are reported using a 15% cut-off. RESULTS A total of 82.7% of NS5A inhibitor-experienced patients (205/248) had baseline NS3 and/or NS5A RASs; 79% had baseline NS5A RASs. SVR12 rates were similar in patients with or without NS3 and/or NS5A RASs, and with or without VOX- or VEL-specific RASs. RASs at NS5A position Y93 were present in 37.3% of patients and 95% achieved SVR12. All patients with ≥2 NS5A RASs achieved SVR12. Baseline NS3 and/or NS5A RASs were present in 46.6% (83/178) of non-NS5A inhibitor DAA-experienced patients, all of whom achieved SVR12. All patients with baseline NS5B nucleoside inhibitor RASs, including two patients with S282T, achieved SVR12. Treatment-selected resistance was seen in one of seven patients who relapsed. CONCLUSIONS Baseline RASs had no impact on virologic response in DAA-experienced patients following treatment with SOF/VEL/VOX for 12 weeks. Selection of viral resistance with virologic relapse was uncommon. LAY SUMMARY In phase III studies, 12 weeks of treatment with the combination of sofosbuvir, velpatasvir and voxilaprevir (SOF/VEL/VOX) cured 97% of patients with hepatitis C virus who failed prior treatment with direct-acting antiviral drugs. Herein, we show that the presence of pretreatment drug resistance did not affect treatment outcome in these patients who had previously received direct-acting antivirals. We also showed that new drug resistance was rare in patients who failed treatment with SOF/VEL/VOX for 12 weeks. This has important implications for the selection of best retreatment strategies for these patients.
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Affiliation(s)
- Christoph Sarrazin
- Medizinische Klinik 1, Goethe University Hospital, Frankfurt, Germany; St. Josefs-Hospital, Wiesbaden, Germany
| | | | | | | | | | - Stuart K Roberts
- Alfred Health Gastroenterology Department and Monash University Melbourne, Australia
| | | | | | | | | | | | | | | | | | - Hongmei Mo
- Gilead Sciences, Inc, Foster City, CA, USA
| | | | | | - Stefan Zeuzem
- Medizinische Klinik 1, Goethe University Hospital, Frankfurt, Germany
| | - Steven L Flamm
- Northwestern Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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10
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Pretreatment Hepatitis C Virus NS5A/NS5B Resistance-Associated Substitutions in Genotype 1 Uruguayan Infected Patients. DISEASE MARKERS 2018; 2018:2514901. [PMID: 30186532 PMCID: PMC6112080 DOI: 10.1155/2018/2514901] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/30/2018] [Accepted: 06/10/2018] [Indexed: 12/18/2022]
Abstract
Hepatitis C Virus (HCV) infection treatment has dramatically changed with the advent of direct-acting antiviral agents (DAAs). However, the efficacy of DAAs can be attenuated by the presence of resistance-associated substitutions (RASs) before and after treatment. Indeed, RASs detected in DAA treatment-naïve HCV-infected patients could be useful for clinical management and outcome prediction. Although the frequency of naturally occurring HCV NS5A and NS5B RASs has been addressed in many countries, there are only a few reports on their prevalence in the South American region. The aim of this study was to investigate the presence of RASs to NS5A and NS5B inhibitors in a DAA treatment naïve cohort of Uruguayan patients infected with chronic hepatitis C and compare them with reports from other South American countries. Here, we found that naturally occurring substitutions conferring resistance to NS5A and NS5B inhibitors were present in 8% and 19.2%, respectively, of treatment-naïve HCV genotype 1 infected patients. Importantly, the baseline substitutions in NS5A and NS5B herein identified differ from the studies previously reported in Brazil. Furthermore, Uruguayan strains subtype 1a clustered within all major world clades, showing that HCV variants currently circulating in this country are characterized by a remarkable genetic diversity.
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van Buuren N, Tellinghuisen TL, Richardson CD, Kirkegaard K. Transmission genetics of drug-resistant hepatitis C virus. eLife 2018; 7:32579. [PMID: 29589830 PMCID: PMC5916564 DOI: 10.7554/elife.32579] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 03/22/2018] [Indexed: 12/11/2022] Open
Abstract
Antiviral development is plagued by drug resistance and genetic barriers to resistance are needed. For HIV and hepatitis C virus (HCV), combination therapy has proved life-saving. The targets of direct-acting antivirals for HCV infection are NS3/4A protease, NS5A phosphoprotein and NS5B polymerase. Differential visualization of drug-resistant and -susceptible RNA genomes within cells revealed that resistant variants of NS3/4A protease and NS5A phosphoprotein are cis-dominant, ensuring their direct selection from complex environments. Confocal microscopy revealed that RNA replication complexes are genome-specific, rationalizing the non-interaction of wild-type and variant products. No HCV antivirals yet display the dominance of drug susceptibility shown for capsid proteins of other viruses. However, effective inhibitors of HCV polymerase exact such high fitness costs for drug resistance that stable genome selection is not observed. Barriers to drug resistance vary with target biochemistry and detailed analysis of these barriers should lead to the use of fewer drugs. Viruses are simple organisms that consist of genetic information and a few types of proteins. They cannot replicate on their own, and instead hijack the molecular machinery of a host cell to produce more of themselves. Inside an infected cell, the genetic information of the virus is replicated and ‘read’ to create viral proteins. These components are then assembled to form a new generation of viruses. During this process, genetic errors may occur that lead to modifications in the viral proteins, and help the virus become resistant to treatment. For instance, a viral protein that used to be targeted by a drug can change slightly and not be recognized anymore. Currently, the most efficient way to fight drug resistance is to use combination therapy, where several drugs are given at the same time. This strategy is successful, for example to treat infections with the hepatitis C virus, but it is also expensive, especially for developing countries. An alternative approach is dominant-drug targeting, which exploits the fact that both drug-resistant and drug-susceptible viruses are ‘born’ in the same cell. There, the susceptible viruses can overwhelm and ‘mask’ the benefits of the resistant ones. For example, proteins from resistant strains, which are no longer detected by a treatment, can bind to proteins from susceptible viruses; drugs will still be able to recognize these resulting viral structures. The proteins that operate in such ways are potential dominant-drug targets. However, resistant and susceptible strains can also cohabit without any contacts if their proteins do not interact with each other. Now, van Buuren et al. screen several viral proteins, including one called NS5A, to test whether a dominant drug target exists for the hepatitis C virus. Only a few molecules of a drug that targets NS5A can stop the virus from growing. In theory, drug-bound NS5A proteins could block their non-drug-bound neighbors, but when these drugs have been used on their own, resistance quickly emerged. Experiments showed that NS5A is not a dominant drug target because the drug-resistant and drug-susceptible proteins do not mix. Unless ‘forced’ in the laboratory, NS5A proteins only bind to the ones produced by the same strain of virus. This explains why resistant viruses quickly take over when NS5A drugs are the sole treatment. However, other hepatitis C proteins, such as the HCV core protein, are known to mix during the assembly of the virus, and thus are likely be dominant drug targets.
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Affiliation(s)
- Nicholas van Buuren
- Department of Genetics, Stanford University School of Medicine, Stanford, United States
| | | | | | - Karla Kirkegaard
- Department of Genetics, Stanford University School of Medicine, Stanford, United States
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12
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El-Tahan RR, Ghoneim AM, Zaghloul H. 5' UTR and NS5B-based genotyping of hepatitis C virus in patients from Damietta governorate, Egypt. J Adv Res 2018; 10:39-47. [PMID: 30046475 PMCID: PMC6057237 DOI: 10.1016/j.jare.2018.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 01/04/2018] [Accepted: 01/07/2018] [Indexed: 12/11/2022] Open
Abstract
Chronic hepatitis C virus (HCV) infection is a main health problem in Egypt causing high rates of mortalities. Egypt has the highest HCV prevalence in the world, with specific HCV subtypes epidemic and circulating extensively in the country. Different antiviral therapy protocols have been implemented for treating Egyptian HCV patients. Due to the limited data about HCV in Egypt, this study aimed to genotype HCV strains circulating in the Nile Delta Damietta governorate and to investigate the variation in the nonstructural 5B (NS5B) region targeted by the newly approved antiviral drugs. Thirty HCV samples from treatment-naïve patients were genotyped by restriction fragment length polymorphism. Some samples were genotyped by direct sequencing of their 5' untranslated region (UTR) and NS5B regions. Phylogenetic analysis was also performed on the sequences of their NS5B regions. Fourteen new sequences have been deposited in the GenBank database. Results showed that subtype 4a was prevalent in addition to subtype 1g. None of the previously reported NS5B substitutions were detected in the sequenced isolates from treatment-naïve patients, which may be a good predictor for efficient treatment of HCV Egyptian patients with Sofosbuvir. Further studies on Sofosbuvir treated-HCV Egyptian patients are required to investigate whether any NS5B substitutions can confer resistance to treatment.
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Affiliation(s)
- Radwa R. El-Tahan
- Zoology Department, Faculty of Science, Damietta University, New Damietta, P.O. 34517, Damietta, Egypt
| | - Ahmed M. Ghoneim
- Zoology Department, Faculty of Science, Damietta University, New Damietta, P.O. 34517, Damietta, Egypt
| | - Hosam Zaghloul
- Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt
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13
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Selisko B, Papageorgiou N, Ferron F, Canard B. Structural and Functional Basis of the Fidelity of Nucleotide Selection by Flavivirus RNA-Dependent RNA Polymerases. Viruses 2018; 10:v10020059. [PMID: 29385764 PMCID: PMC5850366 DOI: 10.3390/v10020059] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 01/25/2018] [Accepted: 01/27/2018] [Indexed: 12/22/2022] Open
Abstract
Viral RNA-dependent RNA polymerases (RdRps) play a central role not only in viral replication, but also in the genetic evolution of viral RNAs. After binding to an RNA template and selecting 5'-triphosphate ribonucleosides, viral RdRps synthesize an RNA copy according to Watson-Crick base-pairing rules. The copy process sometimes deviates from both the base-pairing rules specified by the template and the natural ribose selectivity and, thus, the process is error-prone due to the intrinsic (in)fidelity of viral RdRps. These enzymes share a number of conserved amino-acid sequence strings, called motifs A-G, which can be defined from a structural and functional point-of-view. A co-relation is gradually emerging between mutations in these motifs and viral genome evolution or observed mutation rates. Here, we review our current knowledge on these motifs and their role on the structural and mechanistic basis of the fidelity of nucleotide selection and RNA synthesis by Flavivirus RdRps.
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Affiliation(s)
- Barbara Selisko
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - Nicolas Papageorgiou
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - François Ferron
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - Bruno Canard
- CNRS, Aix-Marseille Université, AFMB, UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
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14
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Xu HT, Hassounah SA, Colby-Germinario SP, Oliveira M, Fogarty C, Quan Y, Han Y, Golubkov O, Ibanescu I, Brenner B, Stranix BR, Wainberg MA. Purification of Zika virus RNA-dependent RNA polymerase and its use to identify small-molecule Zika inhibitors. J Antimicrob Chemother 2017; 72:727-734. [PMID: 28069884 DOI: 10.1093/jac/dkw514] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 11/01/2016] [Indexed: 12/21/2022] Open
Abstract
Background The viral RNA-dependent RNA polymerase (RdRp) enzymes of the Flaviviridae family are essential for viral replication and are logically important targets for development of antiviral therapeutic agents. Zika virus (ZIKV) is a rapidly re-emerging human pathogen for which no vaccine or antiviral agent is currently available. Methods To facilitate development of ZIKV RdRp inhibitors, we have established an RdRp assay using purified recombinant ZIKV NS5 polymerase. Results We have shown that both the hepatitis C virus (HCV) nucleoside inhibitor sofosbuvir triphosphate and a pyridoxine-derived non-nucleoside small-molecule inhibitor, DMB213, can act against ZIKV RdRp activity at IC 50 s of 7.3 and 5.2 μM, respectively, in RNA synthesis reactions catalysed by recombinant ZIKV NS5 polymerase. Cell-based assays confirmed the anti-ZIKV activity of sofosbuvir and DMB213 with 50% effective concentrations (EC 50 s) of 8.3 and 4.6 μM, respectively. Control studies showed that DMB213 did not inhibit recombinant HIV-1 reverse transcriptase and showed only very weak inhibition of HIV-1 integrase strand-transfer activity. The S604T substitution in motif B of the ZIKV RdRp, which corresponds to the S282T substitution in motif B of HCV RdRp, which confers resistance to nucleotide inhibitors, also conferred resistance to sofosbuvir triphosphate, but not to DMB213. Enzyme assays showed that DMB213 appears to be competitive with natural nucleoside triphosphate (NTP) substrates. Conclusions Recombinant ZIKV RdRp assays can be useful tools for the screening of both nucleos(t)ide compounds and non-nucleotide metal ion-chelating agents that interfere with ZIKV replication.
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Affiliation(s)
- Hong-Tao Xu
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Said A Hassounah
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Susan P Colby-Germinario
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Maureen Oliveira
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Clare Fogarty
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Yudong Quan
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Yingshan Han
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Olga Golubkov
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Ilinca Ibanescu
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | - Bluma Brenner
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada
| | | | - Mark A Wainberg
- Jewish General Hospital, McGill University AIDS Centre, Lady Davis Institute for Medical Research, Montreal, Quebec, Canada.,Department of Medicine, McGill University, Montreal, Quebec, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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15
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Xu HT, Colby-Germinario SP, Hassounah SA, Fogarty C, Osman N, Palanisamy N, Han Y, Oliveira M, Quan Y, Wainberg MA. Evaluation of Sofosbuvir (β-D-2'-deoxy-2'-α-fluoro-2'-β-C-methyluridine) as an inhibitor of Dengue virus replication<sup/>. Sci Rep 2017; 7:6345. [PMID: 28740124 PMCID: PMC5524696 DOI: 10.1038/s41598-017-06612-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/31/2017] [Indexed: 12/26/2022] Open
Abstract
We evaluated Sofosbuvir (SOF), the anti-hepatitis C virus prodrug of β-d-2'-deoxy-2'-α-fluoro-2'-β-C-methyluridine-5'-monophosphate, for potential inhibitory activity against DENV replication. Both cell-based and biochemical assays, based on use of purified DENV full-length NS5 enzyme, were studied. Cytopathic effect protection and virus yield reduction assays confirmed that SOF possessed anti-DENV activity in cell culture with a 50% effective concentration (EC50) of 4.9 µM and 1.4 µM respectively. Real-time RT-PCR verified that SOF inhibits generation of viral RNA with an EC50 of 9.9 µM. Purified DENV NS5 incorporated the active triphosphate form (SOF-TP) into nascent RNA, causing chain-termination. Relative to the natural UTP, the incorporation efficiency of SOF-TP was low (discrimination value = 327.5). In a primer extension assay, SOF-TP was active against DENV NS5 wild-type polymerase activity with an IC50 of 14.7 ± 2.5 µM. The S600T substitution in the B Motif of DENV polymerase conferred 4.3-fold resistance to SOF-TP; this was due to decreased incorporation efficiency rather than enhanced excision of the incorporated SOF nucleotide. SOF has antiviral activity against DENV replication. The high discrimination value in favor of UTP in enzyme assays may not necessarily preclude antiviral activity in cells. SOF may be worthy of evaluation against severe DENV infections in humans.
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Affiliation(s)
- Hong-Tao Xu
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.
| | - Susan P Colby-Germinario
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Said A Hassounah
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Clare Fogarty
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Nathan Osman
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Navaneethan Palanisamy
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada.,HBIGS, University of Heidelberg, Heidelberg, Germany
| | - Yingshan Han
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Maureen Oliveira
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Yudong Quan
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada
| | - Mark A Wainberg
- McGill University AIDS Centre, Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada.,Department of Medicine, McGill University, Montreal, Quebec, Canada.,Department of Microbiology and Immunology, McGill University, Montreal, Quebec, Canada
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16
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Raj VS, Hundie GB, Schürch AC, Smits SL, Pas SD, Le Pogam S, Janssen HLA, de Knegt RJ, Osterhaus ADME, Najera I, Boucher CA, Haagmans BL. Identification of HCV Resistant Variants against Direct Acting Antivirals in Plasma and Liver of Treatment Naïve Patients. Sci Rep 2017; 7:4688. [PMID: 28680115 PMCID: PMC5498547 DOI: 10.1038/s41598-017-04931-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/22/2017] [Indexed: 02/06/2023] Open
Abstract
Current standard-of-care treatment of chronically infected hepatitis C virus (HCV) patients involves direct-acting antivirals (DAA). However, concerns exist regarding the emergence of drug -resistant variants and subsequent treatment failure. In this study, we investigate potential natural drug-resistance mutations in the NS5B gene of HCV genotype 1b from treatment-naïve patients. Population-based sequencing and 454 deep sequencing of NS5B gene were performed on plasma and liver samples obtained from 18 treatment- naïve patients. The quasispecies distribution in plasma and liver samples showed a remarkable overlap in each patient. Although unique sequences in plasma or liver were observed, in the majority of cases the most dominant sequences were shown to be identical in both compartments. Neither in plasma nor in the liver codon changes were detected at position 282 that cause resistance to nucleos(t)ide analogues. However, in 10 patients the V321I change conferring resistance to nucleos(t)ide NS5B polymerase inhibitors and in 16 patients the C316N/Y/H non-nucleoside inhibitors were found mainly in liver samples. In conclusion, 454-deep sequencing of liver and plasma compartments in treatment naïve patients provides insight into viral quasispecies and the pre-existence of some drug-resistant variants in the liver, which are not necessarily present in plasma.
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Affiliation(s)
- V Stalin Raj
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Anita C Schürch
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Saskia L Smits
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands.,Viroclinics Biosciences BV, Rotterdam, The Netherlands
| | - Suzan D Pas
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Sophie Le Pogam
- Virology Discovery, Pharma Research Early Development Hoffmann La Roche, Nutley, NJ, USA
| | - Harry L A Janssen
- Department of Gastroenterology and Hepatology, Erasmus Medical Center, Rotterdam, The Netherlands.,Division of Gastroenterology, University Health Network, Toronto, Canada
| | - Rob J de Knegt
- Department of Gastroenterology and Hepatology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Albert D M E Osterhaus
- Artemis One health, Utrecht, The Netherlands.,Center for Infection Medicine and Zoonoses Research, University of Veterinary Medicine, Hannover, Germany
| | - Isabel Najera
- Virology Discovery, Pharma Research Early Development Hoffmann La Roche, Nutley, NJ, USA
| | - Charles A Boucher
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Bart L Haagmans
- Department of Viroscience, Erasmus Medical Center, Rotterdam, The Netherlands.
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17
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Xu S, Doehle B, Rajyaguru S, Han B, Barauskas O, Feng J, Perry J, Dvory-Sobol H, Svarovskaia ES, Miller MD, Mo H. In vitro selection of resistance to sofosbuvir in HCV replicons of genotype-1 to -6. Antivir Ther 2017; 22:587-597. [PMID: 28248189 DOI: 10.3851/imp3149] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2017] [Indexed: 10/20/2022]
Abstract
BACKGROUND Sofosbuvir is a nucleoside analogue inhibitor of the HCV NS5B polymerase approved for treatment of HCV-infected patients in combination with ribavirin or with other antivirals. It has activity against all genotypes of HCV. Resistance to sofosbuvir in genotype-1 and -2 HCV is conferred by the S282T substitution in NS5B. METHODS To begin to define the correlates of resistance to sofosbuvir in other genotypes, we performed selection experiments in cell culture using cell lines containing subgenomic replicons derived from genotypes-1b, -2a, -3a and -4a, or chimeric replicons in a genotype-1b background but encoding genotype-2b, -5a and -6a NS5B polymerase. RESULTS In every case, S282T was selected following passage in the presence of increasing concentrations of sofosbuvir for 10 to 15 weeks. When introduced as a site-directed mutant, S282T conferred reductions in sofosbuvir susceptibility of between 2.4 and 19.4-fold. Other substitutions observed during the selections had relatively less impact on susceptibility, such as N237S in genotype-6a (2.5-fold). Replication capacity was affected by the introduction of S282T in all genotypes to variable extents (3.2% to 22% of wild type). CONCLUSIONS These results confirm that S282T is the primary sofosbuvir resistance-associated substitution and that replication capacity is reduced when it is present in all genotypes of HCV.
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Affiliation(s)
- Simin Xu
- Gilead Sciences, Foster City, CA, USA
| | | | | | - Bin Han
- Gilead Sciences, Foster City, CA, USA
| | | | - Joy Feng
- Gilead Sciences, Foster City, CA, USA
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18
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Lu G, Gong P. A structural view of the RNA-dependent RNA polymerases from the Flavivirus genus. Virus Res 2017; 234:34-43. [PMID: 28131854 DOI: 10.1016/j.virusres.2017.01.020] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 01/15/2017] [Accepted: 01/22/2017] [Indexed: 12/17/2022]
Abstract
The RNA-dependent RNA polymerase (RdRP) from the Flavivirus genus is naturally fused to a methyltransferase (MTase), and the full-length protein is named nonstructural protein 5 (NS5). Similar to polymerases from other RNA viruses, the flavivirus RdRP has an encircled human right hand architecture with palm, fingers, and thumb domains surrounding its polymerase active site. In contrast to primer-dependent RdRPs that have a spacious front channel to accommodate the template-product RNA duplex, the flavivirus RdRP has a priming element as a thumb domain insertion, partially occupying the front channel to facilitate the de novo initiation process. Seven catalytic motifs A through G have been identified for all viral RdRPs and have highly homologous spatial arrangement around the active site despite low sequence conservation in several motifs if considering all viral families, forming an important basis to the understandings of the common features for viral RdRPs. In the two different global conformations identified in full-length crystal structures of Japanese encephalitis virus (JEV) and Dengue virus (DENV) NS5 proteins, the MTase approaches the RdRP consistently from the backside but its orientation and the interaction details with the RdRP are drastically different. Further investigations are required to clarify the conservation, functional relevance, and relationship of these conformations. Remaining challenges with respect to flavivirus RdRP structure are also discussed.
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Affiliation(s)
- Guoliang Lu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, No. 44 Xiao Hong Shan, Wuhan, Hubei 430071, China
| | - Peng Gong
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, No. 44 Xiao Hong Shan, Wuhan, Hubei 430071, China.
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19
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Potisopon S, Ferron F, Fattorini V, Selisko B, Canard B. Substrate selectivity of Dengue and Zika virus NS5 polymerase towards 2'-modified nucleotide analogues. Antiviral Res 2016; 140:25-36. [PMID: 28041959 DOI: 10.1016/j.antiviral.2016.12.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 12/28/2016] [Accepted: 12/29/2016] [Indexed: 12/11/2022]
Abstract
In targeting the essential viral RNA-dependent RNA-polymerase (RdRp), nucleotide analogues play a major role in antiviral therapies. In the Flaviviridae family, the hepatitis C virus (HCV) can be eradicated from chronically infected patients using a combination of drugs which generally include the 2'-modified uridine analogue Sofosbuvir, delivered as nucleotide prodrug. Dengue and Zika viruses are emerging flaviviruses whose RdRp is closely related to that of HCV, yet no nucleoside drug has been clinically approved for these acute infections. We have purified dengue and Zika virus full-length NS5, the viral RdRps, and used them to assemble a stable binary complex made of NS5 and virus-specific RNA primer/templates. The complex was used to assess the selectivity of NS5 towards nucleotide analogues bearing modifications at the 2'-position. We show that dengue and Zika virus RdRps exhibit the same discrimination pattern: 2'-O-Me > 2'-C-Me-2'-F > 2'-C-Me nucleoside analogues, unlike HCV RdRp for which the presence of the 2'-F is beneficial rendering the discrimination pattern 2'-O-Me > 2'-C-Me ≥ 2'-C-Me-2'-F. Both 2'-C-Me and 2'-C-Me-2'-F analogues act as non-obligate RNA chain terminators. The dengue and Zika NS5 nucleotide selectivity towards 2'-modified NTPs mirrors potency of the corresponding analogues in infected cell cultures.
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Affiliation(s)
- Supanee Potisopon
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France
| | - François Ferron
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France
| | - Véronique Fattorini
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France
| | - Barbara Selisko
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
| | - Bruno Canard
- Aix-Marseille Université, AFMB (Laboratoire d'Architecture et Fonction de Macromolécules Biologiques) UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France; CNRS, AFMB UMR 7257, 163 Avenue de Luminy, 13288 Marseille, France.
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20
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McPhee F, Hernandez D, Zhou N. Effect of minor populations of NS5A and NS5B resistance-associated variants on HCV genotype-3 response to daclatasvir plus sofosbuvir, with or without ribavirin. Antivir Ther 2016; 22:237-246. [PMID: 28008868 DOI: 10.3851/imp3120] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND Treatment of hepatitis C virus (HCV) genotype 3 (GT3) is a medical priority. All-oral treatment of HCV GT3 with daclatasvir (DCV) and sofosbuvir (SOF), with or without ribavirin (RBV), is recommended by several treatment guidelines. The impact of HCV minority populations at amino acid positions in NS5A and NS5B associated with drug resistance on response to DCV+SOF±RBV was assessed in SOF-naive and SOF-experienced HCV patients. METHODS The presence of baseline NS5A or NS5B polymorphisms was assessed in 227 and 167 HCV-GT3-infected patients, respectively, from four clinical studies of DCV+SOF±RBV. Polymorphisms were identified at a sequencing detection threshold of ≥10%, and at ≥1% by next-generation sequencing (NGS) for a subset. RESULTS No SOF resistance-associated polymorphisms were detected at baseline. Among 58 patients with prospective baseline sequencing data at ≥10% and ≥1%, detectable NS5A substitutions at A30 (A30K/R/S/T/V), S62 (S62A/F/K/L/T) or Y93H were 38% more prevalent at ≥1% compared with ≥10% (55% [32/58] versus 41% [24/58] of patients), although sustained virological response (SVR) in patients with these substitutions remained the same at both sequencing thresholds (88%). Only one additional Y93H was detected at ≥1%; the patient achieved SVR. In two virological failures with baseline Y93H, a minority S62L substitution at baseline was enriched from <20% to ≥95% at failure. Treatment-emergent minority populations (at A30, L31, P32, P58 and E92) observed by NGS in four virological failures became undetectable by week 24 post-treatment. CONCLUSIONS Sequencing at a depth of ≥10% appears to be sufficient to predict HCV GT3 response to DCV+SOF±RBV.
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Affiliation(s)
- Fiona McPhee
- Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Dennis Hernandez
- Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
| | - Nannan Zhou
- Bristol-Myers Squibb Research and Development, Wallingford, CT, USA
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21
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Bullard-Feibelman KM, Govero J, Zhu Z, Salazar V, Veselinovic M, Diamond MS, Geiss BJ. The FDA-approved drug sofosbuvir inhibits Zika virus infection. Antiviral Res 2016; 137:134-140. [PMID: 27902933 DOI: 10.1016/j.antiviral.2016.11.023] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 11/24/2016] [Accepted: 11/24/2016] [Indexed: 01/08/2023]
Abstract
The rapidly expanding Zika virus (ZIKV) epidemic has affected thousands of individuals with severe cases causing Guillain-Barré syndrome, congenital malformations, and microcephaly. Currently, there is no available vaccine or therapy to prevent or treat ZIKV infection. We evaluated whether sofosbuvir, an FDA-approved nucleotide polymerase inhibitor for the distantly related hepatitis C virus, could have antiviral activity against ZIKV infection. Cell culture studies established that sofosbuvir efficiently inhibits replication and infection of several ZIKV strains in multiple human tumor cell lines and isolated human fetal-derived neuronal stem cells. Moreover, oral treatment with sofosbuvir protected against ZIKV-induced death in mice. These results suggest that sofosbuvir may be a candidate for further evaluation as a therapy against ZIKV infection in humans.
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Affiliation(s)
| | - Jennifer Govero
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Zhe Zhu
- Department of Stem Cell Biology and Regenerative Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Vanessa Salazar
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
| | - Milena Veselinovic
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Michael S Diamond
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA; Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO, USA; Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, MO, USA; The Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, Saint Louis, MO, USA
| | - Brian J Geiss
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA; School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA.
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22
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Mizokami M, Dvory-Sobol H, Izumi N, Nishiguchi S, Doehle B, Svarovskaia ES, De-Oertel S, Knox S, Brainard DM, Miller MD, Mo H, Sakamoto N, Takehara T, Omata M. Resistance Analyses of Japanese Hepatitis C-Infected Patients Receiving Sofosbuvir or Ledipasvir/Sofosbuvir Containing Regimens in Phase 3 Studies. J Viral Hepat 2016; 23:780-8. [PMID: 27196675 DOI: 10.1111/jvh.12549] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/21/2016] [Indexed: 12/11/2022]
Abstract
High rates of sustained virologic response (SVR) has been achieved in Japanese patients with chronic hepatitis C virus (HCV) genotype (GT)1 and GT2 infection treated with ledipasvir/sofosbuvir (LDV/SOF) ±ribavirin (RBV) and SOF+RBV, respectively. We evaluated the effect of baseline HCV NS5A and NS5B resistance-associated variants (RAVs) on treatment outcome and characterized variants at virologic failure. Baseline deep sequencing for NS5A and NS5B genes was performed for all GT1 patients. Deep sequencing of NS5A (GT1 only) and NS5B (GT1 and GT2) was performed for patients who failed treatment or discontinued early with detectable HCV RNA (i.e., >25 IU/mL). In patients with HCV GT1 infection, 22.3% (GT1a: 2/11; GT1b: 74/330) had ≥1 baseline NS5A RAV. The most frequent NS5A RAVs in GT1b were Y93H (17.9%, 59/330) and L31M (2.4%, 8/330). Despite the presence of NS5A RAVs at baseline, 100% and 97% of patients achieved SVR12, compared with 100% and 99% for those with no NS5A RAVs with LDV/SOF and LDV/SOF+RBV, respectively. All patients with NS5B RAVs at baseline achieved SVR12. Of the 153 patients with GT2 infection (GT2a 60.1%, GT2b 39.9%), 3.3% (5/153) experienced viral relapse. No S282T or other NS5B RAVs were detected at baseline or relapse; no change in susceptibility to SOF or RBV was observed at relapse. In conclusion, LDV/SOF and SOF+RBV demonstrate a high barrier to resistance in Japanese patients with HCV GT1 and GT2 infection. The presence of baseline NS5A RAVs did not impact treatment outcome in GT1 Japanese patients treated with LDV/SOF for 12 weeks.
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Affiliation(s)
- M Mizokami
- The Research Center for Hepatitis & Immunology, National Center for Global Health and Medicine, Chiba, Japan
| | | | - N Izumi
- Musashino Red Cross Hospital, Tokyo, Japan
| | | | - B Doehle
- Gilead Sciences Inc., Foster City, CA, USA
| | | | | | - S Knox
- Gilead Sciences Inc., Foster City, CA, USA
| | | | - M D Miller
- Gilead Sciences Inc., Foster City, CA, USA
| | - H Mo
- Gilead Sciences Inc., Foster City, CA, USA
| | | | | | - M Omata
- Yamanashi Prefectural Hospital Organization, Yamanashi, Japan
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23
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Sarrazin C, Dvory-Sobol H, Svarovskaia ES, Doehle BP, Pang PS, Chuang SM, Ma J, Ding X, Afdhal NH, Kowdley KV, Gane EJ, Lawitz E, Brainard DM, McHutchison JG, Miller MD, Mo H. Prevalence of Resistance-Associated Substitutions in HCV NS5A, NS5B, or NS3 and Outcomes of Treatment With Ledipasvir and Sofosbuvir. Gastroenterology 2016; 151:501-512.e1. [PMID: 27296509 DOI: 10.1053/j.gastro.2016.06.002] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 06/01/2016] [Accepted: 06/03/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS We evaluated the effects of baseline hepatitis C virus (HCV) NS5A, NS5B, and NS3 resistance-associated substitutions (RASs) on response to the combination of ledipasvir and sofosbuvir, with or without ribavirin, in patients with HCV genotype 1 infection. METHODS We analyzed data from 2144 participants in phase 2 and 3 studies of patients with HCV genotype 1a or b infection who received the combination of ledipasvir (90 mg) and sofosbuvir (400 mg) (ledipasvir/sofosbuvir) once daily, with or without ribavirin twice daily. Population and/or deep sequence analyses of the HCV NS3, NS5A, and NS5B genes were performed on blood samples collected at baseline. RESULTS Overall, 16.0% of patients had detectable baseline RASs in NS5A. Among patients with HCV genotype 1b infection, there was no significant effect of baseline RASs in NS5A on sustained viral response 12 weeks after the end of treatment (SVR12) with ledipasvir/sofosbuvir and only a small effect in patients with HCV genotype 1a infection. RASs in NS5A that increased the half-maximal effective concentration to ledipasvir by more than 100-fold reduced the rate of SVR12 in treatment-naive patients given ledipasvir/sofosbuvir for 8 weeks (P = .011), but not for 12 weeks. These same baseline NS5A RASs reduced the percentage of treatment-experienced patients who achieved an SVR12 to 12 weeks (but not 24 weeks) ledipasvir/sofosbuvir (P < .001). These RASs had a small effect in patients given ledipasvir/sofosbuvir in combination with ribavirin for 12 weeks. Overall, 2.5% of patients had baseline NS5B nucleotide inhibitor RASs (L159F, N142T, S282G, or L320S) and all achieved an SVR12. Of patients previously treated with protease inhibitors, 53.7% had RASs in NS3 and 96.5% achieved an SVR12. CONCLUSIONS Baseline RASs in NS5A have minimal effects on patient responses to ledipasvir/sofosbuvir therapy. When these RASs do have effects, they could be largely overcome by extending treatment duration or through treatment intensification.
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Affiliation(s)
| | | | | | | | | | | | - Julie Ma
- Gilead Sciences, Inc, Foster City, California
| | - Xiao Ding
- Gilead Sciences, Inc, Foster City, California
| | - Nezam H Afdhal
- Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | | | - Edward J Gane
- New Zealand Liver Transplant Unit, Auckland City Hospital, Auckland, New Zealand
| | - Eric Lawitz
- Texas Liver institute, University of Texas Health Science Center, San Antonio, Texas
| | | | | | | | - Hongmei Mo
- Gilead Sciences, Inc, Foster City, California
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24
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Abstract
The treatment of HCV infection has evolved at an extremely rapid pace over the past few years. The development of direct-acting antiviral agents, which potently inhibit different stages in the viral life cycle, has led to the replacement of interferon with well-tolerated oral therapies with cure rates of >90% in most patient populations. Understanding the mechanisms of action of the various agents as well as related issues, including the molecular basis for resistance, helps to guide drug development and clinical use. In this Review, we provide a mechanistic description of NS3/4A protease inhibitors, nucleotide and non-nucleotide inhibitors of the NS5B viral polymerase and inhibitors of the NS5A protein, followed by a summary of clinical data from studies of each drug class alone and in combination. Remaining challenges in drug development efforts are also discussed.
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25
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Kwo PY, Badshah MB. Treatment of HCV in Patients who Failed First-Generation PI Therapy: a Review of Current Literature. Curr Gastroenterol Rep 2016; 17:462. [PMID: 26342813 DOI: 10.1007/s11894-015-0462-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The addition of the first direct-acting antiviral agents, the NS3 protease inhibitors boceprevir or telaprevir, to peg interferon and ribavirin was a major advance in the treatment of genotype 1 hepatitis C individuals with sustained virological response (SVR) rates of 63-75 %. Those who did not achieve SVR had high rates of resistance-associated variants against NS3 protease domain. Retreatment options for those who have failed first-generation protease inhibitors generally are guided by retreatment with direct-acting antiviral agents from other classes. Phase 2 and phase 3 data have demonstrated that retreatment with 12-24 weeks of a NS5B inhibitor (sofosbuvir) in combination with a NS5a inhibitor (daclatasvir or ledipasvir) with or without ribavirin can achieve SVR at high rates comparable to treatment-naive individuals.
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Affiliation(s)
- Paul Y Kwo
- Department of Medicine, Division of Gastroenterology/Hepatology, Indiana University School of Medicine, 975 W. Walnut, IB 327, Indianapolis, IN, 46202-5121, USA,
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26
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Dellafiore MA, Montserrat JM, Iribarren AM. Modified Nucleoside Triphosphates for In-vitro Selection Techniques. Front Chem 2016; 4:18. [PMID: 27200340 PMCID: PMC4854868 DOI: 10.3389/fchem.2016.00018] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 04/05/2016] [Indexed: 12/22/2022] Open
Abstract
The development of SELEX (Selective Enhancement of Ligands by Exponential Enrichment) provides a powerful tool for the search of functional oligonucleotides with the ability to bind ligands with high affinity and selectivity (aptamers) and for the discovery of nucleic acid sequences with diverse enzymatic activities (ribozymes and DNAzymes). This technique has been extensively applied to the selection of natural DNA or RNA molecules but, in order to improve chemical and structural diversity as well as for particular applications where further chemical or biological stability is necessary, the extension of this strategy to modified oligonucleotides is desirable. Taking into account these needs, this review intends to collect the research carried out during the past years, focusing mainly on the use of modified nucleotides in SELEX and the development of mutant enzymes for broadening nucleoside triphosphates acceptance. In addition, comments regarding the synthesis of modified nucleoside triphosphate will be briefly discussed.
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Affiliation(s)
- María A Dellafiore
- Laboratorio de Química de Ácidos Nucleicos, INGEBI (CONICET) Ciudad Autónoma de Buenos Aires, Argentina
| | - Javier M Montserrat
- Laboratorio de Química de Ácidos Nucleicos, INGEBI (CONICET)Ciudad Autónoma de Buenos Aires, Argentina; Instituto de Ciencias, Universidad Nacional de General SarmientoLos Polvorines, Argentina
| | - Adolfo M Iribarren
- Laboratorio de Química de Ácidos Nucleicos, INGEBI (CONICET)Ciudad Autónoma de Buenos Aires, Argentina; Laboratorio de Biotransformaciones, Universidad Nacional de QuilmesBernal, Argentina
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27
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A Complex Network of Interactions between S282 and G283 of Hepatitis C Virus Nonstructural Protein 5B and the Template Strand Affects Susceptibility to Sofosbuvir and Ribavirin. Antimicrob Agents Chemother 2016; 60:2018-27. [PMID: 26824949 DOI: 10.1128/aac.02436-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/05/2016] [Indexed: 01/17/2023] Open
Abstract
The hepatitis C virus (HCV) RNA-dependent RNA-polymerase NS5B is essentially required for viral replication and serves as a prominent drug target. Sofosbuvir is a prodrug of a nucleotide analog that interacts selectively with NS5B and has been approved for HCV treatment in combination with ribavirin. Although the emergence of resistance to sofosbuvir is rarely seen in the clinic, the S282T mutation was shown to decrease susceptibility to this drug. S282T was also shown to confer hypersusceptibility to ribavirin, which is of potential clinical benefit. Here we devised a biochemical approach to elucidate the underlying mechanisms. Recent crystallographic data revealed a hydrogen bond between S282 and the 2'-hydroxyl of the bound nucleotide, while the adjacent G283 forms a hydrogen bond with the 2'-hydroxyl of the residue of the template that base pairs with the nucleotide substrate. We show that DNA-like modifications of the template that disrupt hydrogen bonding with G283 cause enzyme pausing with natural nucleotides. However, the specifically introduced DNA residue of the template reestablishes binding and incorporation of sofosbuvir in the context of S282T. Moreover, the DNA-like modifications of the template prevent the incorporation of ribavirin in the context of the wild-type enzyme, whereas the S282T mutant enables the binding and incorporation of ribavirin under the same conditions. Together, these findings provide strong evidence to show that susceptibility to sofosbuvir and ribavirin depends crucially on a network of interdependent hydrogen bonds that involve the adjacent residues S282 and G283 and their interactions with the incoming nucleotide and complementary template residue, respectively.
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28
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Qing J, Luo R, Wang Y, Nong J, Wu M, Shao Y, Tang R, Yu X, Yin Z, Sun Y. Resistance analysis and characterization of NITD008 as an adenosine analog inhibitor against hepatitis C virus. Antiviral Res 2015; 126:43-54. [PMID: 26724382 DOI: 10.1016/j.antiviral.2015.12.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 12/19/2015] [Accepted: 12/22/2015] [Indexed: 12/18/2022]
Abstract
Hepatitis disease caused by hepatitis C virus (HCV) is a severe threat to global public health, affecting approximately 3% of the world's population. Sofosbuvir (PSI-7977), a uridine nucleotide analog inhibitor targeting the HCV NS5B polymerase, was approved by FDA at the end of 2013 and represents a key step towards a new era in the management of HCV infection. Previous study identified NITD008, an adenosine nucleoside analog, as the specific inhibitor against dengue virus and showed good antiviral effect on other flaviviruses or enteroviruses. In this report, we systematically analyzed the anti-HCV profile of NITD008, which was discovered to effectively suppress the replication of different strains of HCV in human hepatoma cells with a low nanomolar activity. On genotype 2a virus, or 2a, 1a, and 1b replicon cells, EC50 values were 8.7 nM, 93.3 nM, 60.0 nM and 67.2 nM, and selective index values were >2298.9, >214.4, >333.3, >298.5 respectively. We demonstrated that resistance to NITD008 was conferred by mutation in NS5B (S282T) in the HCV infectious virus genotype 2a (JFH-1). Then, we compared the resistant profiles of NITD008 and PSI-7977, and found that the folds change of EC50 of NITD008 to full replicon cells containing mutation S282T was much bigger than PSI-7977(folds 76.50 vs. 4.52). Analysis of NITD008 cross-resistance against previously reported NS5B drug-selected mutations showed that the resistance pattern of NITD008 was not completely similar to PSI-7977, and meanwhile, S282T resistant mutation to NITD008 emerge more easily in cell culture than PSI-7977. Interestingly, NITD008 displayed significant synergistic effects with the NS5B polymerase inhibitor PSI-7977, however, only additive effects with alpha interferon (IFNα-2b), ribavirin, and an NS3 protease inhibitor. These results verify that NITD008 is an effective analog inhibitor against hepatitis C virus and a good research tool as a supplement to other types of nucleoside analogs.
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Affiliation(s)
- Jie Qing
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Rui Luo
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yaxin Wang
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Junxiu Nong
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ming Wu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yan Shao
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruoyi Tang
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xi Yu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zheng Yin
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China.
| | - Yuna Sun
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Science, Beijing 100101, China.
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29
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Rashidzadeh H, Bhadresa S, Good SS, Larsson Cohen M, Gupta KS, Rush WR. Overcoming stability challenges in the quantification of tissue nucleotides: determination of 2'-C-methylguanosine triphosphate concentration in mouse liver. Biol Pharm Bull 2015; 38:380-8. [PMID: 25757919 DOI: 10.1248/bpb.b14-00565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A conventional, rapid and high throughput method for tissue extraction and accurate and selective LC-MS/MS quantification of 2'-C-methylguanosine triphosphate (2'-MeGTP) in mouse liver was developed and qualified. Trichloroacetic acid (TCA) was used as the tissue homogenization reagent that overcomes instability challenges of liver tissue nucleotide triphosphates due to instant ischemic degradation to mono- and diphosphate nucleotides. Degradation of 2'-MeGTP was also minimized by harvesting livers using in situ clamp-freezing or snap-freezing techniques. The assay also included a sample clean-up procedure using weak anion exchange solid phase extraction followed by ion exchange chromatography and tandem mass spectrometry detection. The linear assay range was from 50 to 10000 pmol/mL concentration in liver homogenate (250-50000 pmol/g in liver tissue). The method was qualified over three intraday batches for accuracy, precision, selectivity and specificity. The assay was successfully applied to pharmacokinetic studies of 2'-MeGTP in liver tissue samples after single oral doses of IDX184, a nucleotide prodrug inhibitor of the viral polymerase for the treatment of hepatitis C, to mice. The study results suggested that the clamp-freezing liver collection method was marginally more effective in preventing 2'-MeGTP degradation during liver tissue collection compared to the snap-freezing method.
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30
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Identification of a Pyridoxine-Derived Small-Molecule Inhibitor Targeting Dengue Virus RNA-Dependent RNA Polymerase. Antimicrob Agents Chemother 2015; 60:600-8. [PMID: 26574011 DOI: 10.1128/aac.02203-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/10/2015] [Indexed: 01/14/2023] Open
Abstract
The viral RNA-dependent RNA polymerase (RdRp) activity of the dengue virus (DENV) NS5 protein is an attractive target for drug design. Here, we report the identification of a novel class of inhibitor (i.e., an active-site metal ion chelator) that acts against DENV RdRp activity. DENV RdRp utilizes a two-metal-ion mechanism of catalysis; therefore, we constructed a small library of compounds, through mechanism-based drug design, aimed at chelating divalent metal ions in the catalytic site of DENV RdRp. We now describe a pyridoxine-derived small-molecule inhibitor that targets DENV RdRp and show that 5-benzenesulfonylmethyl-3-hydroxy-4-hydroxymethyl-pyridine-2-carboxylic acid hydroxyamide (termed DMB220) inhibited the RdRp activity of DENV serotypes 1 to 4 at low micromolar 50% inhibitory concentrations (IC50s of 5 to 6.7 μM) in an enzymatic assay. The antiviral activity of DMB220 against DENV infection was also verified in a cell-based assay and showed a 50% effective concentration (EC50) of <3 μM. Enzyme assays proved that DMB220 was competitive with nucleotide incorporation. DMB220 did not inhibit the enzymatic activity of recombinant HIV-1 reverse transcriptase and showed only weak inhibition of HIV-1 integrase strand transfer activity, indicating high specificity for DENV RdRp. S600T substitution in the DENV RdRp, which was previously shown to confer resistance to nucleoside analogue inhibitors (NI), conferred 3-fold hypersusceptibility to DMB220, and enzymatic analyses showed that this hypersusceptibility may arise from the decreased binding/incorporation efficiency of the natural NTP substrate without significantly impacting inhibitor binding. Thus, metal ion chelation at the active site of DENV RdRp represents a viable anti-DENV strategy, and DMB220 is the first of a new class of DENV inhibitor.
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31
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Biochemical Evaluation of the Inhibition Properties of Favipiravir and 2'-C-Methyl-Cytidine Triphosphates against Human and Mouse Norovirus RNA Polymerases. Antimicrob Agents Chemother 2015; 59:7504-16. [PMID: 26392512 DOI: 10.1128/aac.01391-15] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 09/14/2015] [Indexed: 11/20/2022] Open
Abstract
Norovirus (NoV) is a positive-sense single-stranded RNA virus that causes acute gastroenteritis and is responsible for 200,000 deaths per year worldwide. No effective vaccine or treatment is available. Recent studies have shown that the nucleoside analogs favipiravir (T-705) and 2'-C-methyl-cytidine (2CM-C) inhibit NoV replication in vitro and in animal models, but their precise mechanism of action is unknown. We evaluated the molecular interactions between nucleoside triphosphates and NoV RNA-dependent RNA polymerase (NoVpol), the enzyme responsible for replication and transcription of NoV genomic RNA. We found that T-705 ribonucleoside triphosphate (RTP) and 2CM-C triphosphate (2CM-CTP) equally inhibited human and mouse NoVpol activities at concentrations resulting in 50% of maximum inhibition (IC50s) in the low micromolar range. 2CM-CTP inhibited the viral polymerases by competing directly with natural CTP during primer elongation, whereas T-705 RTP competed mostly with ATP and GTP at the initiation and elongation steps. Incorporation of 2CM-CTP into viral RNA blocked subsequent RNA synthesis, whereas T-705 RTP did not cause immediate chain termination of NoVpol. 2CM-CTP and T-705 RTP displayed low levels of enzyme selectivity, as they were both recognized as substrates by human mitochondrial RNA polymerase. The level of discrimination by the human enzyme was increased with a novel analog of T-705 RTP containing a 2'-C-methyl substitution. Collectively, our data suggest that 2CM-C inhibits replication of NoV by acting as a classic chain terminator, while T-705 may inhibit the virus by multiple mechanisms of action. Understanding the precise mechanism of action of anti-NoV compounds could provide a rational basis for optimizing their inhibition potencies and selectivities.
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32
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Appleby TC, Perry JK, Murakami E, Barauskas O, Feng J, Cho A, Fox D, Wetmore DR, McGrath ME, Ray AS, Sofia MJ, Swaminathan S, Edwards TE. Viral replication. Structural basis for RNA replication by the hepatitis C virus polymerase. Science 2015; 347:771-5. [PMID: 25678663 DOI: 10.1126/science.1259210] [Citation(s) in RCA: 253] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nucleotide analog inhibitors have shown clinical success in the treatment of hepatitis C virus (HCV) infection, despite an incomplete mechanistic understanding of NS5B, the viral RNA-dependent RNA polymerase. Here we study the details of HCV RNA replication by determining crystal structures of stalled polymerase ternary complexes with enzymes, RNA templates, RNA primers, incoming nucleotides, and catalytic metal ions during both primed initiation and elongation of RNA synthesis. Our analysis revealed that highly conserved active-site residues in NS5B position the primer for in-line attack on the incoming nucleotide. A β loop and a C-terminal membrane-anchoring linker occlude the active-site cavity in the apo state, retract in the primed initiation assembly to enforce replication of the HCV genome from the 3' terminus, and vacate the active-site cavity during elongation. We investigated the incorporation of nucleotide analog inhibitors, including the clinically active metabolite formed by sofosbuvir, to elucidate key molecular interactions in the active site.
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Affiliation(s)
- Todd C Appleby
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA.
| | - Jason K Perry
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Eisuke Murakami
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Ona Barauskas
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Joy Feng
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Aesop Cho
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - David Fox
- Beryllium, 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Diana R Wetmore
- Beryllium, 7869 NE Day Road West, Bainbridge Island, WA 98110, USA
| | - Mary E McGrath
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Adrian S Ray
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Michael J Sofia
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - S Swaminathan
- Gilead Sciences, 333 Lakeside Drive, Foster City, CA 94404, USA
| | - Thomas E Edwards
- Beryllium, 7869 NE Day Road West, Bainbridge Island, WA 98110, USA.
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33
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Svarovskaia ES, Dvory-Sobol H, Parkin N, Hebner C, Gontcharova V, Martin R, Ouyang W, Han B, Xu S, Ku K, Chiu S, Gane E, Jacobson IM, Nelson DR, Lawitz E, Wyles DL, Bekele N, Brainard D, Symonds WT, McHutchison JG, Miller MD, Mo H. Infrequent development of resistance in genotype 1-6 hepatitis C virus-infected subjects treated with sofosbuvir in phase 2 and 3 clinical trials. Clin Infect Dis 2014; 59:1666-74. [PMID: 25266287 DOI: 10.1093/cid/ciu697] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Sofosbuvir is a chain-terminating nucleotide analogue inhibitor of the hepatitis C virus (HCV) NS5B RNA polymerase that is efficacious in subjects with HCV genotype 1-6 infection. Sofosbuvir resistance is primarily conferred by the S282T substitution in NS5B. METHODS NS5B sequencing and susceptibility testing of HCV from subjects infected with genotypes 1-6 who participated in phase 2 and 3 sofosbuvir clinical trials was performed. RESULTS No NS5B variants present at baseline among 1645 sofosbuvir-treated subjects were associated with treatment failure; sofosbuvir susceptibility was within 2-fold of reference. Among 282 subjects who did not achieve sustained virologic response, no novel sofosbuvir resistance-associated variants were identified, and the NS5B changes observed did not confer significant reductions in sofosbuvir susceptibility. In 1 subject with S282T observed at relapse 4 weeks after sofosbuvir monotherapy, the resistant variant (13.5-fold reduced sofosbuvir susceptibility, replication capacity <2% of control) became undetectable by deep sequencing 12 weeks after treatment. L159F and V321A were identified as treatment-emergent variants but did not confer resistance to sofosbuvir in the replicon system. CONCLUSIONS These data demonstrate a uniform susceptibility of subject-derived HCV to sofosbuvir, and also show that selection of sofosbuvir-resistant HCV is exceedingly rare and is associated with a significant reduction in viral fitness.
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Affiliation(s)
| | | | - Neil Parkin
- Data First Consulting Inc, Belmont, California
| | | | | | | | | | - Bin Han
- Gilead Sciences, Foster City
| | | | | | | | - Edward Gane
- University of Auckland, Auckland City Hospital, New Zealand
| | | | | | | | - David L Wyles
- Division of Infectious Diseases, University of California, San Diego
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34
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Deval J, Symons JA, Beigelman L. Inhibition of viral RNA polymerases by nucleoside and nucleotide analogs: therapeutic applications against positive-strand RNA viruses beyond hepatitis C virus. Curr Opin Virol 2014; 9:1-7. [PMID: 25194816 PMCID: PMC7102778 DOI: 10.1016/j.coviro.2014.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 12/21/2022]
Abstract
New therapies for infections caused by positive-strand RNA viruses are needed. Novel nucleoside and nucleotide analogs that inhibit HCV have been developed. Some of these molecules also inhibit other positive-strand RNA viruses. Optimization of antiviral potency and/or target delivery is necessary.
A number of important human infections are caused by positive-strand RNA viruses, yet almost none can be treated with small molecule antiviral therapeutics. One exception is the chronic infection caused by hepatitis C virus (HCV), against which new generations of potent inhibitors are being developed. One of the main molecular targets for anti-HCV drugs is the viral RNA-dependent RNA polymerase, NS5B. This review summarizes the search for nucleoside and nucleotide analogs that inhibit HCV NS5B, which led to the FDA approval of sofosbuvir in 2013. Advances in anti-HCV therapeutics have also stimulated efforts to develop nucleoside analogs against other positive-strand RNA viruses. Although it remains to be validated in the clinic, the prospect of using nucleoside analogs to treat acute infections caused by RNA viruses represents an important paradigm shift and a new frontier for future antiviral therapies.
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Affiliation(s)
- Jerome Deval
- Alios BioPharma, Inc., 260 East Grand Avenue, South San Francisco, CA 94080, USA.
| | - Julian A Symons
- Alios BioPharma, Inc., 260 East Grand Avenue, South San Francisco, CA 94080, USA
| | - Leo Beigelman
- Alios BioPharma, Inc., 260 East Grand Avenue, South San Francisco, CA 94080, USA.
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Götte M. Resistance to nucleotide analogue inhibitors of hepatitis C virus NS5B: mechanisms and clinical relevance. Curr Opin Virol 2014; 8:104-8. [PMID: 25128987 DOI: 10.1016/j.coviro.2014.07.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 07/27/2014] [Accepted: 07/28/2014] [Indexed: 11/25/2022]
Abstract
The high barrier to the development of resistance to nucleotide analogue inhibitors of the hepatitis C virus (HCV) RNA-dependent RNA polymerase is an intriguing property of this class of drugs. The S282T substitution in the viral polymerase confers resistance to 2'-C-methylated nucleotide analogues. Although this mutation can be selected in HCV replicons, it has only been identified in very few cases in the clinic. Alternative resistance pathways are likewise rarely seen in vivo. Possible underlying mechanisms that are associated with the selection and establishment of a resistant genotype are discussed in this review.
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Affiliation(s)
- Matthias Götte
- Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Quebec H3A 2B4, Canada; Department of Biochemistry, McGill University, 3655 Sir William Osler Promenade, Montreal, Quebec H3G 1Y6, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, 1110 Pine Avenue West, Montreal, Quebec H3A 1A3, Canada.
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Inhibitors of the tick-borne, hemorrhagic fever-associated flaviviruses. Antimicrob Agents Chemother 2014; 58:3206-16. [PMID: 24663025 DOI: 10.1128/aac.02393-14] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
No antiviral therapies are available for the tick-borne flaviviruses associated with hemorrhagic fevers: Kyasanur Forest disease virus (KFDV), both classical and the Alkhurma hemorrhagic fever virus (AHFV) subtype, and Omsk hemorrhagic fever virus (OHFV). We tested compounds reported to have antiviral activity against members of the Flaviviridae family for their ability to inhibit AHFV replication. 6-Azauridine (6-azaU), 2'-C-methylcytidine (2'-CMC), and interferon alpha 2a (IFN-α2a) inhibited the replication of AHFV and also KFDV, OHFV, and Powassan virus. The combination of IFN-α2a and 2'-CMC exerted an additive antiviral effect on AHFV, and the combination of IFN-α2a and 6-azaU was moderately synergistic. The combination of 2'-CMC and 6-azaU was complex, being strongly synergistic but with a moderate level of antagonism. The antiviral activity of 6-azaU was reduced by the addition of cytidine but not guanosine, suggesting that it acted by inhibiting pyrimidine biosynthesis. To investigate the mechanism of action of 2'-CMC, AHFV variants with reduced susceptibility to 2'-CMC were selected. We used a replicon system to assess the substitutions present in the selected AHFV population. A double NS5 mutant, S603T/C666S, and a triple mutant, S603T/C666S/M644V, were more resistant to 2'-CMC than the wild-type replicon. The S603T/C666S mutant had a reduced level of replication which was increased when M644V was also present, although the replication of this triple mutant was still below that of the wild type. The S603 and C666 residues were predicted to lie in the active site of the AHFV NS5 polymerase, implicating the catalytic center of the enzyme as the binding site for 2'-CMC.
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Hepatitis C virus genetic variability and the presence of NS5B resistance-associated mutations as natural polymorphisms in selected genotypes could affect the response to NS5B inhibitors. Antimicrob Agents Chemother 2014; 58:2781-97. [PMID: 24590484 DOI: 10.1128/aac.02386-13] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Because of the extreme genetic variability of hepatitis C virus (HCV), we analyzed the NS5B polymerase genetic variability in circulating HCV genotypes/subtypes and its impact on the genetic barrier for the development of resistance to clinically relevant nucleoside inhibitors (NIs)/nonnucleoside inhibitors (NNIs). The study included 1,145 NS5B polymerase sequences retrieved from the Los Alamos HCV database and GenBank. The genetic barrier was calculated for drug resistance emergence. Prevalence and genetic barrier were calculated for 1 major NI and 32 NNI resistance variants (13 major and 19 minor) at 21 total NS5B positions. Docking calculations were used to analyze sofosbuvir affinity toward the diverse HCV genotypes. Overall, NS5B polymerase was moderately conserved among all HCV genotypes, with 313/591 amino acid residues (53.0%) showing ≤1% variability and 83/591 residues (14.0%) showing high variability (≥25.1%). Nine NNI resistance variants (2 major variants, 414L and 423I; 7 minor variants, 316N, 421V, 445F, 482L, 494A, 499A, and 556G) were found as natural polymorphisms in selected genotypes. In particular, 414L and 423I were found in HCV genotype 4 (HCV-4) (n = 14/38, 36.8%) and in all HCV-5 sequences (n = 17, 100%), respectively. Regardless of HCV genotype, the 282T major NI resistance variant and 10 major NNI resistance variants (316Y, 414L, 423I/T/V, 448H, 486V, 495L, 554D, and 559G) always required a single nucleotide substitution to be generated. Conversely, the other 3 major NNI resistance variants (414T, 419S, and 422K) were associated with a different genetic barrier score development among the six HCV genotypes. Sofosbuvir docking analysis highlighted a better ligand affinity toward HCV-2 than toward HCV-3, in agreement with the experimental observations. The genetic variability among HCV genotypes, particularly with the presence of polymorphisms at NNI resistance positions, could affect their responsiveness to NS5B inhibitors. A pretherapy HCV NS5B sequencing could help to provide patients with the full efficacy of NNI-containing regimens.
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Welsch C. Genetic barrier and variant fitness in hepatitis C as critical parameters for drug resistance development. DRUG DISCOVERY TODAY. TECHNOLOGIES 2014; 11:19-25. [PMID: 24847649 DOI: 10.1016/j.ddtec.2013.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The approval of direct-acting antiviral agents (DAAs) has marked a pivotal change in the treatment landscape of chronic hepatitis C. As for DAAs targeting other viral diseases, there are concerns regarding the development of resistant viral variants. Their selection allows the virus to escape from drug pressure with subsequent treatment failure. The emergence of resistant variants depends on multiple factors that range from genetic barriers to mutations to the fitness of viral variants. This article illustrates the basic mechanisms underlying development of resistance to specific antiviral agents with a special emphasis on NS3 protease inhibitors. The role of fitness deficits and compensation for variant selection and persistence is discussed together with technical issues in sequencing as well as clinical implications in the use of DAAs now and in the future.
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Ali M, Rehman IU, Idrees M. Emergence of genetically variant Hepatitis C virus population in response to increased antiviral drug pressure, Pakistan. Virus Genes 2014; 48:543-9. [PMID: 24532035 DOI: 10.1007/s11262-014-1047-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 01/30/2014] [Indexed: 01/06/2023]
Abstract
Mutations in NS5B gene of Hepatitis C virus (HCV) have been reported in patients undergoing antiviral therapy. In the present study, we report emerging clade of HCV-3a in patients administered with IFN plus ribavirin therapy for 24 weeks and having low viral loads (<250 IU/mL). Mutations D/N244E, K304R, N/K307G, Q/T329V, and A338V were found associated with these emerging strains. This distinct HCV could be associated with the increased antiviral drug pressure.
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Affiliation(s)
- Muhammad Ali
- Division of Molecular Virology, National Centre of Excellence in Molecular Biology, University of the Punjab, 87-West Canal bank Road, Thokar Niaz baig, Lahore, 53700, Pakistan,
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Analysis of serine codon conservation reveals diverse phenotypic constraints on hepatitis C virus glycoprotein evolution. J Virol 2013; 88:667-78. [PMID: 24173227 DOI: 10.1128/jvi.01745-13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Serine is encoded by two divergent codon types, UCN and AGY, which are not interchangeable by a single nucleotide substitution. Switching between codon types therefore occurs via intermediates (threonine or cysteine) or via simultaneous tandem substitutions. Hepatitis C virus (HCV) chronically infects 2 to 3% of the global population. The highly variable glycoproteins E1 and E2 decorate the surface of the viral envelope, facilitate cellular entry, and are targets for host immunity. Comparative sequence analysis of globally sampled E1E2 genes, coupled with phylogenetic analysis, reveals the signatures of multiple archaic codon-switching events at seven highly conserved serine residues. Limited detection of intermediate phenotypes indicates that associated fitness costs restrict their fixation in divergent HCV lineages. Mutational pathways underlying codon switching were probed via reverse genetics, assessing glycoprotein functionality using multiple in vitro systems. These data demonstrate selection against intermediate phenotypes can act at the structural/functional level, with some intermediates displaying impaired virion assembly and/or decreased capacity for target cell entry. These effects act in residue/isolate-specific manner. Selection against intermediates is also provided by humoral targeting, with some intermediates exhibiting increased epitope exposure and enhanced neutralization sensitivity, despite maintaining a capacity for target cell entry. Thus, purifying selection against intermediates limits their frequencies in globally sampled strains, with divergent functional constraints at the protein level restricting the fixation of deleterious mutations. Overall our study provides an experimental framework for identification of barriers limiting viral substitutional evolution and indicates that serine codon-switching represents a genomic "fossil record" of historical purifying selection against E1E2 intermediate phenotypes.
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Barakat KH, Law J, Prunotto A, Magee WC, Evans DH, Tyrrell DL, Tuszynski J, Houghton M. Detailed computational study of the active site of the hepatitis C viral RNA polymerase to aid novel drug design. J Chem Inf Model 2013; 53:3031-43. [PMID: 24116674 DOI: 10.1021/ci4003969] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The hepatitis C virus (HCV) RNA polymerase, NS5B, is a leading target for novel and selective HCV drug design. The enzyme has been the subject of intensive drug discovery aimed at developing direct acting antiviral (DAA) agents that inhibit its activity and hence prevent the virus from replicating its genome. In this study, we focus on one class of NS5B inhibitors, namely nucleos(t)ide mimetics. Forty-one distinct nucleotide structures have been modeled within the active site of NS5B for the six major HCV genotypes. Our comprehensive modeling protocol employed 287 different molecular dynamics simulations combined with the molecular mechanics/Poisson-Boltzmann surface area (MM-PBSA) methodology to rank and analyze these structures for all genotypes. The binding interactions of the individual compounds have been investigated and reduced to the atomic level. The present study significantly refines our understanding of the mode of action of NS5B-nucleotide-inhibitors, identifies the key structural elements necessary for their activity, and implements the tools for ranking the potential of additional much needed novel inhibitors of NS5B.
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Affiliation(s)
- Khaled H Barakat
- Li Ka Shing Institute of Virology, Department of Medical Microbiology and Immunology, ⊥Department of Oncology, and ∥Department of Physics, University of Alberta , Edmonton, AB, Canada T6G 2E1
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42
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Waheed Y, Bhatti A, Ashraf M. RNA dependent RNA polymerase of HCV: a potential target for the development of antiviral drugs. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2013; 14:247-57. [PMID: 23291407 DOI: 10.1016/j.meegid.2012.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 11/07/2012] [Accepted: 12/11/2012] [Indexed: 02/06/2023]
Abstract
Hepatitis C virus (HCV) is a major cause of hepatocellular carcinoma, cirrhosis and end stage liver disease. More than 200million people are living with HCV worldwide with high morbidity and mortality. There is no vaccine available for this virus; the approved treatment option for the majority of HCV genotypes is the combination of pegylated (Peg) interferon and ribavirin. The therapy has a different response rate on different HCV genotypes and has a number of side effects. Recently, as well as Peg interferon and ribavirin, two protease inhibitors have been introduced to treat patients with HCV genotype 1 infection. The protease inhibitors have rapid onset of resistance and are not approved for use for infections with other HCV genotypes. The HCV NS5B gene encodes RNA dependent RNA polymerase (RdRp), which is the key player in viral replication and is a promising target for the development of antiviral drugs. HCV NS5B has been studied in various biochemical assays, cell based assays and animal model systems. So far, a number of nucleoside and non-nucleoside inhibitors have been screened for effects on viral replication. This review presents a deep insight into the structure and function of HCV polymerase and the effect of various nucleoside and non-nucleoside inhibitors on viral replication.
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Affiliation(s)
- Yasir Waheed
- Atta ur Rahman School of Applied Biosciences, National University of Sciences & Technology (NUST), Islamabad 44000, Pakistan.
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43
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Götte M. The distinct contributions of fitness and genetic barrier to the development of antiviral drug resistance. Curr Opin Virol 2012; 2:644-50. [DOI: 10.1016/j.coviro.2012.08.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 08/15/2012] [Indexed: 01/14/2023]
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Castilho MCB, Martins AN, Horbach IS, Perez RDM, Figueiredo FAF, Pinto PDTA, Nabuco LC, Lima DBD, Tanuri A, Porto LC, Ferreira Júnior ODC. Association of hepatitis C virus NS5B variants with resistance to new antiviral drugs among untreated patients. Mem Inst Oswaldo Cruz 2012; 106:968-75. [PMID: 22241118 DOI: 10.1590/s0074-02762011000800011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 09/08/2011] [Indexed: 01/06/2023] Open
Abstract
Mutations located in the 109-amino acid fragment of NS5B are typically associated with resistance to interferon (IFN) and ribavirin (RIB) and to new antiviral drugs. The prevalence of these mutations was examined in 69 drug-naïve individuals with hepatitis C virus (HCV) infections in Rio de Janeiro, Brazil. Mutations related to non-response to IFN/RIB were observed in all subtypes studied (1a, 1b, 2b, 3a and 4). The most common mutation was Q309R, present in all subtypes, except subtype 2b with frequency above 20%. D244N was detected only in subtype 3a and A333E was detected only in subtype 2b. We did not detect the S282T, S326G or T329I mutations in any of the samples analysed. Of note, the C316N mutation, previously related to a new non-nucleoside compound (HCV796 and AG-021541), was observed in only eight of 33 (24%) samples from subtype 1b. Site 316 was under positive selection in this HCV variant. Our data highlight the presence of previously described resistance mutations in HCV genotypes from drug-naïve patients.
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Affiliation(s)
- Magda Cristina Bernardino Castilho
- Laboratório de Histocompatibilidade e Criopreservação, Policlínica Piquet Carneiro, Departamento de Histologia e Embriologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
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Jaspe RC, Sulbarán YF, Sulbarán MZ, Loureiro CL, Rangel HR, Pujol FH. Prevalence of amino acid mutations in hepatitis C virus core and NS5B regions among Venezuelan viral isolates and comparison with worldwide isolates. Virol J 2012; 9:214. [PMID: 22995142 PMCID: PMC3511240 DOI: 10.1186/1743-422x-9-214] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/18/2012] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Recent reports show that R70Q and L/C91M amino acid substitutions in the core from different hepatitis C virus (HCV) genotypes have been associated with variable responses to interferon (IFN) and ribavirin (RBV) therapy, as well to an increase of hepatocellular carcinoma (HCC) risk, liver steatosis and insulin resistance (IR). Mutations in NS5B have also been associated to IFN, RBV, nucleoside and non-nucleoside inhibitors drug resistance. The prevalence of these mutations was studied in HCV RNA samples from chronically HCV-infected drug-naïve patients. METHODS After amplification of core and NS5B region by nested-PCR, 12 substitutions were analyzed in 266 Venezuelan HCV isolates subtype 1a, 1b, 2a, 2c, 2b, 2j (a subtype frequently found in Venezuela) and 3a (n = 127 and n = 228 for core and NS5B respectively), and compared to isolates from other countries (n = 355 and n = 646 for core and NS5B respectively). RESULTS R70Q and L/C91M core substitutions were present exclusively in HCV G1b. Both substitutions were more frequent in American isolates compared to Asian ones (69% versus 26%, p < 0.001 and 75% versus 45%, p < 0.001 respectively). In Venezuelan isolates NS5B D310N substitution was detected mainly in G3a (100%) and G1a (13%), this later with a significantly higher prevalence than in Brazilian isolates (p = 0.03). The NS5B mutations related to IFN/RBV treatment D244N was mainly found in G3a, and Q309R was present in all genotypes, except G2. Resistance to new NS5B inhibitors (C316N) was only detected in 18% of G1b, with a significantly lower prevalence than in Asian isolates, where this polymorphism was surprisingly frequent (p < 0.001). CONCLUSIONS Genotypical, geographical and regional differences were found in the prevalence of substitutions in HCV core and NS5B proteins. The substitutions found in the Venezuelan G2j type were similar to that found in G2a and G2c isolates. Our results suggest a high prevalence of the R70Q and L/C91M mutations of core protein for G1b and D310N substitution of NS5B protein for the G3a. C316N polymorphism related with resistance to new NS5B inhibitors was only found in G1b. Some of these mutations could be associated with a worse prognosis of the disease in HCV infected patients.
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Affiliation(s)
- Rossana C Jaspe
- Laboratorio de Virología Molecular, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas, Apdo 20632, Caracas 1020-A, Venezuela
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46
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Abstract
The replication of the hepatitis C viral (HCV) genome is accomplished by the NS5B RNA-dependent RNA polymerase (RdRp), for which mechanistic understanding and structure-guided drug design efforts have been hampered by its propensity to crystallize in a closed, polymerization-incompetent state. The removal of an autoinhibitory β-hairpin loop from genotype 2a HCV NS5B increases de novo RNA synthesis by >100-fold, promotes RNA binding, and facilitated the determination of the first crystallographic structures of HCV polymerase in complex with RNA primer-template pairs. These crystal structures demonstrate the structural realignment required for primer-template recognition and elongation, provide new insights into HCV RNA synthesis at the molecular level, and may prove useful in the structure-based design of novel antiviral compounds. Additionally, our approach for obtaining the RNA primer-template-bound structure of HCV polymerase may be generally applicable to solving RNA-bound complexes for other viral RdRps that contain similar regulatory β-hairpin loops, including bovine viral diarrhea virus, dengue virus, and West Nile virus.
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Mayhoub AS. Hepatitis C RNA-dependent RNA polymerase inhibitors: a review of structure-activity and resistance relationships; different scaffolds and mutations. Bioorg Med Chem 2012; 20:3150-61. [PMID: 22516671 DOI: 10.1016/j.bmc.2012.03.049] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Revised: 02/28/2012] [Accepted: 03/21/2012] [Indexed: 11/17/2022]
Abstract
Hepatitis C virus (HCV), like many other flaviviruses, is widely distributed worldwide with estimated chronically infected victims between 170 and 200 million. HCV inherent error-prone RNA-dependent RNA polymerase (RdRp) is an attractive target for medicinal chemists because of the conservative nature of NS5B nucleotide-binding site. In addition, the availability of several crystal structures for HCV RdRp paved the road for conducting rational-based drug design. At the same time, RdRp is responsible for high mutation rate and rapid development of resistance to the clinically-used therapeutics. To improve the viral response, combination therapy is regularly used. The success of co-therapy disciplines depends on targeting two different active sites. This review provides an overview about different scaffolds that target HCV RdPp with insights about their binding modes and possible induced mutant strains.
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Affiliation(s)
- Abdelrahman S Mayhoub
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, and Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, United States.
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48
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Genotype and subtype profiling of PSI-7977 as a nucleotide inhibitor of hepatitis C virus. Antimicrob Agents Chemother 2012; 56:3359-68. [PMID: 22430955 DOI: 10.1128/aac.00054-12] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PSI-7977, a prodrug of 2'-F-2'-C-methyluridine monophosphate, is the purified diastereoisomer of PSI-7851 and is currently being investigated in phase 3 clinical trials for the treatment of hepatitis C. In this study, we profiled the activity of PSI-7977 and its ability to select for resistance using a number of different replicon cells. Results showed that PSI-7977 was active against genotype (GT) 1a, 1b, and 2a (strain JFH-1) replicons and chimeric replicons containing GT 2a (strain J6), 2b, and 3a NS5B polymerase. Cross-resistance studies using GT 1b replicons confirmed that the S282T change conferred resistance to PSI-7977. Subsequently, we evaluated the ability of PSI-7977 to select for resistance using GT 1a, 1b, and 2a (JFH-1) replicon cells. S282T was the common mutation selected among all three genotypes, but while it conferred resistance to PSI-7977 in GT 1a and 1b, JFH-1 GT 2a S282T showed only a very modest shift in 50% effective concentration (EC(50)) for PSI-7977. Sequence analysis of the JFH-1 NS5B region indicated that additional amino acid changes were selected both prior to and after the emergence of S282T. These include T179A, M289L, I293L, M434T, and H479P. Residues 179, 289, and 293 are located within the finger and palm domains, while 434 and 479 are located on the surface of the thumb domain. Data from the JFH-1 replicon variants showed that amino acid changes within the finger and palm domains together with S282T were required to confer resistance to PSI-7977, while the mutations on the thumb domain serve to enhance the replication capacity of the S282T replicons.
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Sofia MJ, Chang W, Furman PA, Mosley RT, Ross BS. Nucleoside, nucleotide, and non-nucleoside inhibitors of hepatitis C virus NS5B RNA-dependent RNA-polymerase. J Med Chem 2012; 55:2481-531. [PMID: 22185586 DOI: 10.1021/jm201384j] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Michael J Sofia
- Pharmasset, Inc., 303A College Road East, Princeton, New Jersey 08540, United States.
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50
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Lauridsen LH, Rothnagel JA, Veedu RN. Enzymatic recognition of 2'-modified ribonucleoside 5'-triphosphates: towards the evolution of versatile aptamers. Chembiochem 2011; 13:19-25. [PMID: 22162282 DOI: 10.1002/cbic.201100648] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Indexed: 01/21/2023]
Abstract
The quest for effective, selective and nontoxic nucleic-acid-based drugs has led to designing modifications of naturally occurring nucleosides. A number of modified nucleic acids have been made in the past decades in the hope that they would prove useful in target-validation studies and therapeutic applications involving antisense, RNAi, aptamer, and ribozyme-based technologies. Since their invention in the early 1990s, aptamers have emerged as a very promising class of therapeutics, with one drug entering the market for the treatment of age-related macular degeneration. To combat the limitations of aptamers containing naturally occurring nucleotides, chemically modified nucleotides have to be used. In order to apply modified nucleotides in aptamer drug development, their enzyme-recognition capabilities must be understood. For this purpose, several modified nucleoside 5'-triphosphates were synthesized and investigated as substrates for various enzymes. Herein, we review studies on the enzyme-recognition of various 2'-sugar-modified NTPs that were carried out with a view to their effective utilization in SELEX processes to generate versatile aptamers.
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Affiliation(s)
- Lasse H Lauridsen
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
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