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Phylogenetic analysis of the 5' untranslated region of HCV from cirrhotic patients in Khyber Pakhtunkhwa, Pakistan. Sci Rep 2021; 11:15023. [PMID: 34294747 PMCID: PMC8298656 DOI: 10.1038/s41598-021-94063-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 06/29/2021] [Indexed: 11/08/2022] Open
Abstract
Hepatitis C virus (HCV), a small, single-stranded RNA virus with a 9.6 kb genome, is one of the most common causes of liver diseases. Sequencing of the 5ʹ untranslated region (UTR) is usually used for HCV genotyping, but it is less important in numerous subtypes due to its scarce sequence variations. This study aimed to identify genotypes using the 5ʹ UTR of HCV from cirrhotic patients of Khyber Pakhtunkhwa (KP). Serum RNA samples (44) were screened by real time PCR to determine the HCV viral load. Nested PCR was performed to identify cDNA and the 5ʹ UTR. The HCV 5′ UTR was sequenced using the Sanger method. MEGA-7 software was used to analyze evolutionary relatedness. After 5ʹ UTR sequencing, 26 samples (59%) were identified as genotype 3, and 2 samples (6%) were identified as genotypes 1, 2 and 4. The most predominant genotype was 3a, and genotype 4 was rarely reported in the phylogenetic tree. Analysis of the HCV 5ʹ UTR is an efficient alternative method for confirmation of various genotypes. Phylogenetic analysis showed that genotype 3 was dominant in the area of KP, Pakistan.
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Vopálenský V, Khawaja A, Rožnovský L, Mrázek J, Mašek T, Pospíšek M. Characterization of Hepatitis C Virus IRES Quasispecies - From the Individual to the Pool. Front Microbiol 2018; 9:731. [PMID: 29740402 PMCID: PMC5928756 DOI: 10.3389/fmicb.2018.00731] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/28/2018] [Indexed: 12/20/2022] Open
Abstract
Hepatitis C virus (HCV) is a single-stranded positive-sense RNA virus from the genus Hepacivirus. The viral genomic +RNA is 9.6 kb long and contains highly structured 5′ and 3′ untranslated regions (UTRs) and codes for a single large polyprotein, which is co- and post-translationally processed by viral and cellular proteases into at least 11 different polypeptides. Most of the 5′ UTR and an initial part of the polyprotein gene are occupied by an internal ribosome entry site (IRES), which mediates cap-independent translation of the viral proteins and allows the virus to overcome cellular antiviral defense based on the overall reduction of the cap-dependent translation initiation. We reconsidered published results concerning a search for possible correlation between patient response to interferon-based antiviral therapy and accumulation of nucleotide changes within the HCV IRES. However, we were unable to identify any such correlation. Rather than searching for individual mutations, we suggest to focus on determination of individual and collective activities of the HCV IRESs found in patient specimens. We developed a combined, fast, and undemanding approach based on high-throughput cloning of the HCV IRES species to a bicistronic plasmid followed by determination of the HCV IRES activity by flow cytometry. This approach can be adjusted for measurement of the individual HCV IRES activity and for estimation of the aggregate ability of the whole HCV population present in the specimen to synthesize viral proteins. To detect nucleotide variations in the individual IRESs, we used denaturing gradient gel electrophoresis (DGGE) analysis that greatly improved identification and classification of HCV IRES variants in the sample. We suggest that determination of the collective activity of the majority of HCV IRES variants present in one patient specimen in a given time represents possible functional relations among variant sequences within the complex population of viral quasispecies better than bare information about their nucleotide sequences. A similar approach might be used for monitoring of sequence variations in quasispecies populations of other RNA viruses in all cases when changes in primary sequence represent changes in measurable and easily quantifiable phenotypes.
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Affiliation(s)
- Václav Vopálenský
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czechia
| | - Anas Khawaja
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czechia
| | - Luděk Rožnovský
- Clinic of Infectious Medicine, University Hospital Ostrava, Ostrava, Czechia
| | - Jakub Mrázek
- Institute of Public Health in Ostrava, Ostrava, Czechia
| | - Tomáš Mašek
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czechia
| | - Martin Pospíšek
- Department of Genetics and Microbiology, Faculty of Science, Charles University, Prague, Czechia
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Theotokis PI, Usher L, Kortschak CK, Schwalbe E, Moschos SA. Profiling the Mismatch Tolerance of Argonaute 2 through Deep Sequencing of Sliced Polymorphic Viral RNAs. MOLECULAR THERAPY. NUCLEIC ACIDS 2017; 9:22-33. [PMID: 29246301 PMCID: PMC5602524 DOI: 10.1016/j.omtn.2017.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Revised: 08/17/2017] [Accepted: 08/17/2017] [Indexed: 01/08/2023]
Abstract
Low allelic and clonal variability among endogenous RNAi targets has focused mismatch tolerance studies to RNAi-active guide strands. However, the inherent genomic instability of RNA viruses such as hepatitis C virus (HCV) gives rise to quasi-species mutants within discrete clones: this facilitates mismatch tolerance studies from a target perspective. We recently quantified the slicing imprecision of Argonaute 2 using small interfering RNA (siRNA) analogs of the DNA-directed RNAi drug TT-034 and next-generation sequencing of 5' RNA ligase-mediated rapid amplification of cDNA ends (RACE-SEQ). Here, we present an open-source, customizable, and computationally light RACE-SEQ bioinformatic pipeline, describing adaptations that semiquantitatively report the impact of RNAi hybridization site mismatches from the target perspective. The analysis shows that Argonaute 2 has a substitution-specific, 3- to 5-log activity window between fully complementary targets and targets with mismatches across positions 10-11. It further focuses the endonucleotic Slicer imprecision around positions 13-17, demonstrating its dependence on guide strand central region complementarity, and potentiation by even a single mismatch. We further propose pharmacogenomics value in testing endogenous targets using recombinant replicon systems and RACE-SEQ to report the pharmacodynamics of sequence-specific oligonucleotide therapeutics against all possible polymorphisms in a population, in a minimally biased, patient-free manner.
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Affiliation(s)
- Pantazis I Theotokis
- Department of Biomedical Sciences, Faculty of Science and Technology, University of Westminster, London W1W 6UW, UK
| | - Louise Usher
- Department of Biomedical Sciences, Faculty of Science and Technology, University of Westminster, London W1W 6UW, UK; Westminster Genomic Services, Faculty of Science and Technology, University of Westminster, London W1W 6UW, UK
| | - Christopher K Kortschak
- Department of Biomedical Sciences, Faculty of Science and Technology, University of Westminster, London W1W 6UW, UK
| | - Ed Schwalbe
- Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle, Tyne and Wear NE1 8ST, UK
| | - Sterghios A Moschos
- Department of Biomedical Sciences, Faculty of Science and Technology, University of Westminster, London W1W 6UW, UK; Westminster Genomic Services, Faculty of Science and Technology, University of Westminster, London W1W 6UW, UK; Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle, Tyne and Wear NE1 8ST, UK.
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Aziz H, Raza A, Irfan J. Optimum predictors of therapeutic outcome in HCV patients in Pakistan. J Med Virol 2015; 88:100-8. [PMID: 26103918 DOI: 10.1002/jmv.24305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2015] [Indexed: 12/30/2022]
Abstract
Hepatitis C virus (HCV) constitutes a major public health issue in Pakistan. Interferon α and ribavirin is used widely in routine practice in HCV infected patients in Pakistan.Treatment prediction is an important tool in therapy management. The present study aims to evaluate trends of predictive variables of treatment outcome in patients with different genotypes. The analysis comprised of 921 patients infected with different HCV genotypes. All the patients received IFN α-2b combined with ribavirin for 24 weeks. Overall, 60.2% patients achieved Sustained virologic response (SVR). In females sustained virologic response (SVR) was higher in age group <40 years (77.2%) than ≥40-50 years (60%) but in male SVR was almost equal in both age groups. We also found higher SVR with low pretreatment viral load (72.4%, P < 0.0001). Sustained Virologic Response in genotype 3a was 63.1%, 3b was 55%, 1a was 36.3% and 1b was 35% 3a +3b was 55.0% and 1a+3a was 42.9%. According to multivariable logistic regression analysis age < 40 years (2.0; 95%CI, 1.49-2.84; P = 0.0001), low pretreatment RNA level<800,000 IU/ml (4.0; 95%CI, 2.64-6.17; P = 0.0001), early virologic response at week 12 (12.3; 95%CI, 8.18-18.58; P < 0.0001) and non-fatty liver (2.5; 95%CI, 3.6-6.2; P = 0.005) showed significance for SVR. Nucleotide substitution in 5'UTR before treatment failed to show any characteristic pattern that has correlation with sustained response. Subtype 3a showed 95% presence among patients with age <40 years while older patients showed 79.9%.
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Affiliation(s)
- Hafsa Aziz
- Nuclear Medicine Oncology and Radiotherapy Institute, Islamabad, Pakistan
| | - Abida Raza
- Nuclear Medicine Oncology and Radiotherapy Institute, Islamabad, Pakistan
| | - Javaid Irfan
- Nuclear Medicine Oncology and Radiotherapy Institute, Islamabad, Pakistan
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Genetic Variability of Hepatitis C Virus (HCV) 5' Untranslated Region in HIV/HCV Coinfected Patients Treated with Pegylated Interferon and Ribavirin. PLoS One 2015; 10:e0125604. [PMID: 25932941 PMCID: PMC4416933 DOI: 10.1371/journal.pone.0125604] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/24/2015] [Indexed: 01/03/2023] Open
Abstract
Association between hepatitis C virus (HCV) quasispecies and treatment outcome among patients with chronic hepatitis C has been the subject of many studies. However, these studies focused mainly on viral variable regions (E1 and E2) and usually did not include human immunodeficiency virus (HIV)-positive patients. The aim of the present study was to analyze heterogeneity of the 5' untranslated region (5'UTR) in HCV/HIV coinfected patients treated with interferon and ribavirin. The HCV 5'UTR was amplified from serum and peripheral blood mononuclear cells (PBMC) samples in 37 HCV/HIV coinfected patients treated for chronic hepatitis C. Samples were collected right before treatment, and at 2, 4, 6, 8, 12, 20, 24, 36, 44, 48, 60, and 72 weeks. Heterogeneity of the 5'UTR was analyzed by single strand conformational polymorphism (SSCP), cloning and sequencing. Sustained virological response (SVR) was achieved in 46% of analyzed HCV/HIV co-infected patients. Stable SSCP band pattern was observed in 22 patients (62.9%) and SVR rate among these patients was 23%. Decline in the number of bands and/or shift in band positions were found in 6 patients (17.1%), 5 (83%) of whom achieved SVR (p=0.009). A novel viral genotype was identified in all but one of these patients. In 5 of these 6 patients a new genotype was dominant. 5'UTR heterogeneity may correlate with interferon and ribavirin treatment outcome. In the analyzed group of HCV/HIV coinfected patients, viral quasispecies stability during treatment favored viral persistence, whereas decrease in the number of variants and/or emergence of new variants was associated with SVR. Among injection drug users (IDU) patients, a new genotype may become dominant during treatment, probably due to the presence of mixed infections with various strains, which have different susceptibility to treatment.
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Next-Generation Sequencing of 5' Untranslated Region of Hepatitis C Virus in Search of Minor Viral Variant in a Patient Who Revealed New Genotype While on Antiviral Treatment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 885:11-23. [PMID: 26747069 DOI: 10.1007/5584_2015_186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The role of mixed infections with different hepatitis C virus (HCV) genotypes in viral persistence, treatment effects, and tissue tropism is unclear. Next-generation sequencing (NGS), which is suitable for analysis of large, genetically diverse populations offers unparalleled advantages for the study of mixed infections. The aim of the study was to determine, using two different deep sequencing strategies (pyrosequencing - 454 Life Sciences/Roche and reversible terminator sequencing-by-synthesis by Illumina), the origin of a novel HCV genotype transiently detectable during antiviral therapy (pre-existing minor population vs. de novo superinfection). Secondly, we compared 5' untranslated region (5'-UTR) variants obtained by the two NGS approaches. 5' UTR amplification products from 9 samples collected from genotype 1b infected patient before, during, and after treatment (4 serum and 5 peripheral blood mononuclear cell - PBMC - samples) were subjected to the next-generation sequencing. The sequencing revealed the presence of two (454/Roche) and one (Illumina) genotype 4 variants in PBMC at Week 16. None of these variants were present either in the preceding or following samples as revealed by both platforms. 454/Roche sequencing detected 24 different 5'-UTR variants: 8 were present in serum and PBMC, 4 only in serum and 12 only in PBMC. Illumina sequencing detected 11 different 5'-UTR variants: 5 in serum and PBMC, 4 only in serum and 2 only in PBMC. Six variants were identical for both sequencing platforms. The difference in variants number was primarily due to variability in two 5'-UTR homopolymeric regions. In conclusion, longitudinal analysis of HCV variants, employing two independent deep sequencing methods, suggests that the transient presence of a different genotype strain in PBMC was a result of superinfection and not a selection of pre-existing minor variant.
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Bukowska-Ośko I, Radkowski M, Pawełczyk A, Rosinska M, Caraballo Cortés K, Płoski R, Berak H, Horban A, Stanczak J, Fic M, Laskus T. Hepatitis C virus 5' untranslated region variability correlates with treatment outcome. J Viral Hepat 2014; 21:551-9. [PMID: 24118647 DOI: 10.1111/jvh.12182] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 09/08/2013] [Indexed: 12/28/2022]
Abstract
Hepatitis C virus (HCV) variability affects viral-host interactions. We analysed HCV 5'untranslated region (5'UTR) in sera and peripheral blood mononuclear cells (PBMC) from chronic hepatitis C patients undergoing antiviral treatment. We studied 139 patients treated with pegylated interferon and ribavirin. The primary endpoint was a sustained virological response (SVR) defined as negative HCV RNA level 24 weeks after the end of therapy. 5'UTR was analysed by single-strand conformational polymorphism (SSCP) and sequencing. The pretreatment SSCP pattern in serum and PBMC differed in 26 (18.7%) patients. During therapy, the SSCP pattern remained stable in 65 (60.8%) patients, number of bands declined in 16 (15.0%), and in 18 (16.8%) patients, changes were qualified as 'shift' indicating change in band positions. In univariate analysis, there was a significant (P ≤ 0.05) positive association between SVR and pretreatment serum and PBMC dissimilarities, initial viral load <10(6) IU/mL, IL-28B CC genotype of the rs12979860 single nucleotide polymorphism and change in the SSCP band pattern (either 'shift' or decline) In multivariable analysis, only low initial viral load, IL-28B genotype, and changes in the SSCP band pattern were independent factors associated with SVR. In conclusion, stability of 5'UTR correlated with infection persistence, while changes correlated with SVR.
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Affiliation(s)
- I Bukowska-Ośko
- Department of Immunopathology, Warsaw Medical University, Warsaw, Poland
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Analysis of genotype 1b hepatitis C virus IRES in serum and peripheral blood mononuclear cells in patients treated with interferon and ribavirin. BIOMED RESEARCH INTERNATIONAL 2014; 2014:175405. [PMID: 25136559 PMCID: PMC4106116 DOI: 10.1155/2014/175405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 06/16/2014] [Indexed: 02/05/2023]
Abstract
Hepatitis C virus (HCV) highly conserved IRES (internal ribosome entry site) sequence, localized within the 5(')-untranslated region (5(')UTR), may determine viral properties like replication efficiency and cell tropism. The aim of the present study was to characterize newly emerging 5(')UTR variants in serum and peripheral blood mononuclear cells (PBMC) in chronic hepatitis C patients treated with interferon (IFN) and ribavirin and to identify their effect on IRES secondary structures. The study group consisted of 87 patients infected with genotype 1b from whom serum and PBMC samples were collected at 9 time points (before, during, and after treatment). New 5(')UTR variants developed in 9 patients. Out of the overall 14 new variants, 9 (64%) were found in PBMC. HCV variants with decreased thermodynamic stability were identified only in PBMC and C183U mutation was the most common one in this compartment. In conclusion, antiviral treatment may favor emergence of new 5(')UTR variants both in blood and in PBMC compartments. However, variants developing in the latter compartment were predicted to have lower thermodynamic stability of the IRES secondary structures compared to serum strains. C-U change in position 183, which has not been described previously, might indicate viral adaptation to lymphoid cells.
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Chan SW. Establishment of chronic hepatitis C virus infection: Translational evasion of oxidative defence. World J Gastroenterol 2014; 20:2785-2800. [PMID: 24659872 PMCID: PMC3961964 DOI: 10.3748/wjg.v20.i11.2785] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 12/03/2013] [Accepted: 01/15/2014] [Indexed: 02/06/2023] Open
Abstract
Hepatitis C virus (HCV) causes a clinically important disease affecting 3% of the world population. HCV is a single-stranded, positive-sense RNA virus belonging to the genus Hepacivirus within the Flaviviridae family. The virus establishes a chronic infection in the face of an active host oxidative defence, thus adaptation to oxidative stress is key to virus survival. Being a small RNA virus with a limited genomic capacity, we speculate that HCV deploys a different strategy to evade host oxidative defence. Instead of counteracting oxidative stress, it utilizes oxidative stress to facilitate its own survival. Translation is the first step in the replication of a plus strand RNA virus so it would make sense if the virus can exploit the host oxidative defence in facilitating this very first step. This is particularly true when HCV utilizes an internal ribosome entry site element in translation, which is distinctive from that of cap-dependent translation of the vast majority of cellular genes, thus allowing selective translation of genes under conditions when global protein synthesis is compromised. Indeed, we were the first to show that HCV translation was stimulated by an important pro-oxidant-hydrogen peroxide in hepatocytes, suggesting that HCV is able to adapt to and utilize the host anti-viral response to facilitate its own translation thus allowing the virus to thrive under oxidative stress condition to establish chronicity. Understanding how HCV translation is regulated under oxidative stress condition will advance our knowledge on how HCV establishes chronicity. As chronicity is the initiator step in disease progression this will eventually lead to a better understanding of pathogenicity, which is particularly relevant to the development of anti-virals and improved treatments of HCV patients using anti-oxidants.
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Chevaliez S, Bouvier-Alias M, Rodriguez C, Soulier A, Poveda JD, Pawlotsky JM. The Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0, real-time PCR assay accurately quantifies hepatitis C virus genotype 4 RNA. J Clin Microbiol 2013; 51:1078-82. [PMID: 23325825 PMCID: PMC3666793 DOI: 10.1128/jcm.02004-12] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Accepted: 12/26/2012] [Indexed: 12/12/2022] Open
Abstract
Accurate hepatitis C virus (HCV) RNA quantification is mandatory for the management of chronic hepatitis C therapy. The first-generation Cobas AmpliPrep/Cobas TaqMan HCV test (CAP/CTM HCV) underestimated HCV RNA levels by >1-log10 international units/ml in a number of patients infected with HCV genotype 4 and occasionally failed to detect it. The aim of this study was to evaluate the ability of the Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0 (CAP/CTM HCV v2.0), to accurately quantify HCV RNA in a large series of patients infected with different subtypes of HCV genotype 4. Group A comprised 122 patients with chronic HCV genotype 4 infection, and group B comprised 4 patients with HCV genotype 4 in whom HCV RNA was undetectable using the CAP/CTM HCV. Each specimen was tested with the third-generation branched DNA (bDNA) assay, CAP/CTM HCV, and CAP/CTM HCV v2.0. The HCV RNA level was lower in CAP/CTM HCV than in bDNA in 76.2% of cases, regardless of the HCV genotype 4 subtype. In contrast, the correlation between bDNA and CAP/CTM HCV v2.0 values was excellent. CAP/CTM HCV v2.0 accurately quantified HCV RNA levels in the presence of an A-to-T substitution at position 165 alone or combined with a G-to-A substitution at position 145 of the 5' untranslated region of HCV genome. In conclusion, CAP/CTM HCV v2.0 accurately quantifies HCV RNA in genotype 4 clinical specimens, regardless of the subtype, and can be confidently used in clinical trials and clinical practice with this genotype.
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Affiliation(s)
- Stéphane Chevaliez
- National Reference Center for Viral Hepatitis B, C, and Delta, Department of Virology, Hôpital Henri Mondor, Université Paris-Est, Créteil, France.
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Motavaf M, Safari S, Alavian SM. Therapeutic potential of RNA interference: a new molecular approach to antiviral treatment for hepatitis C. J Viral Hepat 2012; 19:757-65. [PMID: 23043382 DOI: 10.1111/jvh.12006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Hepatitis C virus (HCV) infection remains a major cause of chronic liver disease with an estimated 170 million carriers worldwide. Current treatments have significant side effects and have met with only partial success. Therefore, alternative antiviral drugs that efficiently block virus production are needed. During recent decades, RNA interference (RNAi) technology has not only become a powerful tool for functional genomics but also represents a new therapeutic approach for treating human diseases including viral infections. RNAi is a sequence-specific and post-transcriptional gene silencing process mediated by double-stranded RNA (dsRNA). As the HCV genome is a single-stranded RNA that functions as both a messenger RNA (mRNA) and replication template, it is an attractive target for the study of RNAi-based viral therapies. In this review, we will give a brief overview about the history and current status of RNAi and focus on its potential application as a therapeutic option for treatment for HCV infection.
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Piñeiro D, Martinez-Salas E. RNA structural elements of hepatitis C virus controlling viral RNA translation and the implications for viral pathogenesis. Viruses 2012. [PMID: 23202462 PMCID: PMC3497050 DOI: 10.3390/v4102233] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hepatitis C virus (HCV) genome multiplication requires the concerted action of the viral RNA, host factors and viral proteins. Recent studies have provided information about the requirement of specific viral RNA motifs that play an active role in the viral life cycle. RNA regulatory motifs controlling translation and replication of the viral RNA are mostly found at the 5' and 3' untranslated regions (UTRs). In particular, viral protein synthesis is under the control of the internal ribosome entry site (IRES) element, a complex RNA structure located at the 5'UTR that recruits the ribosomal subunits to the initiator codon. Accordingly, interfering with this RNA structural motif causes the abrogation of the viral cycle. In addition, RNA translation initiation is modulated by cellular factors, including miRNAs and RNA-binding proteins. Interestingly, a RNA structural motif located at the 3'end controls viral replication and establishes long-range RNA-RNA interactions with the 5'UTR, generating functional bridges between both ends on the viral genome. In this article, we review recent advances on virus-host interaction and translation control modulating viral gene expression in infected cells.
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Affiliation(s)
- David Piñeiro
- Centro de Biología Molecular Severo Ochoa, Nicolas Cabrera, 1, Cantoblanco, 28049 Madrid, Spain.
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Bolcic F, Laufer N, Torres C, Cassino L, Reynoso R, Quarleri J. Longitudinal analysis of the 5'UTR, E2-PePHD and NS5A-PKRBD genomic regions of hepatitis C virus genotype 1a in association with the response to peginterferon and ribavirin therapy in HIV-coinfected patients. Antiviral Res 2012; 95:72-81. [PMID: 22683884 DOI: 10.1016/j.antiviral.2012.05.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Revised: 05/22/2012] [Accepted: 05/26/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND The rate of non-response to pegylated interferon plus ribavirin (peg-IFN+RBV) in HCV/HIV coinfected patients is higher than in HCV-monoinfected patients. In this sense, the contribution of HCV genetic variability is unknown. The 5' untranslated (5'UTR), the nonstructural 5A (NS5A) and the second envelope (E2) HCV genomic regions have been implicated to peg-IFN therapy response. The proteins appear to block interferon (IFN)-induced RNA-dependent protein kinase (PKR) and the 5'UTR may influence the viral lymphotropism. METHODS We examined comparatively the pretreatment HCV variability between HIV coinfected and HCV monoinfected patients as well as assessed longitudinally the impact of peg-IFN+RBV on HCV variability when HIV is co-present. For this purpose, 15 HIV coinfected and 20 HCV monoinfected patients were compared. They were peg-IFN+RBV non-responders and infected with HCV 1a. RESULTS Irrespectively of the HIV-coexistence, at baseline the amino acid variation in the NS5A-related domains was significantly higher than in the E2-PePHD (p<0.001). The number of amino acid variations (mean±SD) at the NS5A-ISDR domain was higher among HCV/HIV patients than HCV-monoinfected ones (1.80±0.77 vs. 0.95±1.05; p=0.009) but such difference was slightly lower when comparing NS5A-PKRBD sequences (2.47±1.13 vs. 1.60±1.57; p=0.06). No differences were found at the E2-PePHD (0±0 vs. 0.2±0.4). At intra-HIV coinfected patient level, only minor (HCV genetic analysis) or no (HCV substitution rate and quasispecies heterogeneity) changes were observed during therapy (basal, 24h, 4weeks, and 12weeks). CONCLUSIONS Among HCV-1a/HIV coinfected and HCV-monoinfected peg-IFN+RBV non-responder patients, the HCV variability at the 5'UTR, E2-PePHD and NS5A-PKRBD/ISDR domains was mostly comparable exhibiting a low number of variations. Four well-defined amino acid substitutions in NS5A-ISDR domain appeared most frequently when HIV coexists. The interferon-based therapy did not exert any effect in the variation, selection or diversity in the above mentioned HCV regions that could influence clinical responsiveness to IFN therapy.
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Affiliation(s)
- Federico Bolcic
- Instituto de Investigaciones Biomédicas en Retrovirus y Sida, Facultad de Medicina, Universidad de Buenos Aires, Argentina
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Li YP, Ramirez S, Gottwein JM, Bukh J. Non-genotype-specific role of the hepatitis C virus 5' untranslated region in virus production and in inhibition by interferon. Virology 2011; 421:222-34. [PMID: 22029937 DOI: 10.1016/j.virol.2011.10.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 06/15/2011] [Accepted: 10/03/2011] [Indexed: 12/18/2022]
Abstract
The 5' untranslated region (5'UTR) of hepatitis C virus (HCV) is structured into four domains (I-IV) with numerous genotype-specific nucleotides. It is unknown whether the polymorphisms confer genotype-specific functions to the 5'UTR. Using viable JFH1-based Core-NS2 recombinants, we developed and characterized HCV genotypes 1-7 recombinants with highly diverse 5'UTRs (genotypes 1a and 3a), 2a recombinants (J6/JFH1) with 5'UTR of genotypes 1-6 or with heterotypic chimeric (1a/3a and 3a/1a) 5'UTR domains I, II or III, and 1a recombinants with 5'UTR domain I of genotypes 1-6. All were fully functional in Huh7.5 cells; therefore, the 5'UTR apparently functions in a non-genotype-specific manner in HCV production in vitro. However, adenine at the 5'-terminus was required. We demonstrated that J6/JFH1 with 5'UTR of genotypes 1-6 responded similarly to interferon-α2b. This study provides novel insight into the role of the 5'UTR in the HCV life cycle and facilitates HCV basic research and testing of 5'UTR-targeting antivirals.
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Affiliation(s)
- Yi-Ping Li
- Copenhagen Hepatitis C Program, Department of Infectious Diseases and Clinical Research Centre, Copenhagen University Hospital, Hvidovre, Denmark
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15
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Shi G, Yagyu F, Shimizu Y, Shimizu K, Oshima M, Iwamoto A, Gao B, Liu W, Gao GF, Kitamura Y. Flow cytometric assay using two fluorescent proteins for the function of the internal ribosome entry site of hepatitis C virus. Cytometry A 2011; 79:653-60. [PMID: 21710641 DOI: 10.1002/cyto.a.21094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 04/04/2011] [Accepted: 05/17/2011] [Indexed: 12/17/2022]
Abstract
The initiation of translation in hepatitis C virus (HCV) occurs at the internal ribosome entry site (IRES) located at the 5'-end of its genomic RNA. To study the function of HCV IRES, we constructed a reporter plasmid that generates a bicistronic mRNA encoding two fluorescent proteins: cap-dependent DsRed2 and IRES-dependent Azami Green (AG). We introduced the plasmid into Huh7.5.1 and HEK293 cells and measured the relative IRES activity from the ratio of AG's signal to DsRed2's in individual cells using flow cytometry. To compare our method and a conventional biochemical method, we constructed a structurally similar reporter in which Renilla and Firefly luciferases replace DsRed2 and AG, respectively. With these systems, we found that the IRES A164G substitution decreased its activity, that interferon alpha affected the IRES activity in a cell type-specific manner, and that a synthetic micro-RNA targeting IRES was able to suppress the gene expression. In conclusion, the two methods were comparable in sensitivity in the studies of IRES mutations and host cell types. We discussed the significance of our findings and potential advantage of the cytometric assay: application to the molecular study of the HCV translation and to screening anti-IRES drugs.
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Affiliation(s)
- Guoli Shi
- China-Japan Joint Laboratory of Molecular Immunology and Molecular Microbiology, Institute of Microbiology, Chinese Academy of Sciences, Chaoyang District, Beijing 100101, China
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16
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Moretti F, Bolcic F, Mammana L, Bouzas MB, Laufer N, Quarleri J. The hepatitis C virus 5'UTR genomic region remains highly conserved under HAART: a 4- to 8-year longitudinal study from HCV/HIV co-infected patients. AIDS Res Hum Retroviruses 2010; 26:527-32. [PMID: 20455757 DOI: 10.1089/aid.2009.0237] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Franco Moretti
- Centro Nacional de Referencia para el SIDA, Dto. Microbiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina
| | - Federico Bolcic
- Centro Nacional de Referencia para el SIDA, Dto. Microbiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Lilia Mammana
- Unidad de Virología, Hospital Muñiz, Buenos Aires, Argentina
| | | | - Natalia Laufer
- Centro Nacional de Referencia para el SIDA, Dto. Microbiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina
- Unidad de Enfermedades Infecciosas, Hospital Fernández, Buenos Aires, Argentina
| | - Jorge Quarleri
- Centro Nacional de Referencia para el SIDA, Dto. Microbiología, Facultad de Medicina, Universidad de Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
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17
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Viral factors influencing the response to the combination therapy of peginterferon plus ribavirin in chronic hepatitis C. J Gastroenterol 2009; 44:1009-15. [PMID: 19756352 DOI: 10.1007/s00535-009-0126-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2009] [Accepted: 08/13/2009] [Indexed: 02/04/2023]
Abstract
Hepatitis C virus (HCV) is a single-stranded RNA virus known for its high genetic variability owing to the lack of a proofreading mechanism of its RNA dependent RNA polymerase. Until now, numerous studies have been undertaken to clarify the correlation between pretreatment HCV genetic variability and the therapeutic response. Even with the recent combination therapy of peginterferon plus ribavirin for chronic hepatitis C, viral response is variable, and only half of treated patients could clear the virus [sustained viral response (SVR)]. In this review, the contribution of viral genetic variability affecting the treatment outcome is discussed according to each HCV genomic region.
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18
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Araújo FMG, Machado-Lima A, Durham AM, Teixeira R, Oliveira G. Sequence and structural analysis of the 5' noncoding region of hepatitis C virus in patients with chronic infection. J Med Virol 2009; 81:1212-9. [PMID: 19475610 DOI: 10.1002/jmv.21507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Hepatitis C virus (HCV), exhibits considerable genetic diversity, but presents a relatively well conserved 5' noncoding region (5' NCR) among all genotypes. In this study, the structural features and translational efficiency of the HCV 5' NCR sequences were analyzed using the programs RNAfold, RNAshapes and RNApdist and with a bicistronic dual luciferase expression system, respectively. RNA structure prediction software indicated that base substitutions will alter potentially the 5' NCR structure. The heterogeneous sequence observed on 5' NCR led to important changes in their translation efficiency in different cell culture lines. Interactions of the viral RNA with cellular transacting factors may vary according to the cell type and viral genome polymorphisms that may result in the translational efficiency observed.
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19
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Araújo FMG, Sonoda IV, Rodrigues NB, Teixeira R, Redondo RAF, Oliveira GC. Genetic variability in the 5' UTR and NS5A regions of hepatitis C virus RNA isolated from non-responding and responding patients with chronic HCV genotype 1 infection. Mem Inst Oswaldo Cruz 2009; 103:611-4. [PMID: 18949335 DOI: 10.1590/s0074-02762008000600018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 08/19/2008] [Indexed: 02/05/2023] Open
Abstract
Sequence variation among different hepatitis C virus (HCV) isolates has adaptive significance and reflects the modes and intensities of selection mechanisms operating on the virus. In this work, we sought to investigate using classical population genetics parameters, the genetic variability of HCV genotype 1 using the 5' UTR and NS5A regions from treatment non-responding and responding groups of patients. Both regions showed low genetic variability and the 5' UTR showed neutral deviation. No differences were observed in the nonsynonymous/synonymous nucleotide substitution ratio among groups for NS5A. The analysis of molecular variance test of the 5' UTR region showed an 11.94% variation among groups. Phylogenetic analysis showed no correlation between sequence variations and therapeutic responses.
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Affiliation(s)
- Flávio M G Araújo
- Instituto de Pesquisa René Rachou-Fiocruz, Belo Horizonte, MG, Brasil.
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20
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Sequence variability at the internal ribosome entry site of the HCV genome in relation to therapy outcome. ARCH BIOL SCI 2009. [DOI: 10.2298/abs0902205j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Different types of interferon are widely used to treat hepatitis C virus (HCV) infection. Results obtained in vitro suggest that interferon inhibits internal ribosome entry site (IRES)-mediated translation of the HCV genome. To elucidate the possible effect of the nucleotide sequence of IRES on therapy outcome, we compared HCV isolates from patients with sustained response and non-response to interferon/ribavirin combination therapy. In 56 analyzed HCV isolates, nucleotide changes appeared strictly in the stem-loop IIIb region, the stem part from 243 nt to 248 nt, and the polypyrimidine-II region. The natural sequence variability of IRES in isolates of genotype 3a was significantly higher than in isolates of genotype 1b (p < 0.05). The average number of nucleotide changes in genotype 3a correlated with response to therapy (p < 0.05).
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21
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A mutational shift from domain III to II in the internal ribosome entry site of hepatitis C virus after interferon-ribavirin therapy. Arch Virol 2008; 153:1575-9. [PMID: 18592133 DOI: 10.1007/s00705-008-0143-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 05/21/2008] [Indexed: 12/21/2022]
Abstract
We focused on the relationship between variation in the IRES of hepatitis C virus (HCV) genotype 1b and clinical outcome, since the internal ribosome entry site (IRES) has a comparatively low heterogeneity and it might be easy to find unique substitutions. Patients infected with HCV were selected using strict criteria, and unique mutations in the IRES were extracted by the subtraction of common mutations. We found that most mutations accumulated in domain III (dIII) of IRES in sustained virological responders (SVRs) and non-SVRs before therapy. However, these mutations were exclusively observed in domain II (dII) in non-SVR at 2 weeks after the start of therapy.
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22
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Germanidis G, Metallidis S, Lazaraki G, Pawlotsky J, Nikolaidis P. NS5A Sequences of Hepatitis C Virus Genotype 1 and Interferon Resistance: Where Are We? J Infect Dis 2008; 198:154-5. [DOI: 10.1086/588709] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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23
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Mutations in E2-PePHD, NS5A-PKRBD, NS5A-ISDR, and NS5A-V3 of hepatitis C virus genotype 1 and their relationships to pegylated interferon-ribavirin treatment responses. J Virol 2008; 82:6644-53. [PMID: 18448540 DOI: 10.1128/jvi.02231-07] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mutations in several subgenomic regions of hepatitis C virus (HCV) have been implicated in influencing the response to interferon (IFN) therapy. Sequences within HCV NS5A (PKR binding domain [PKRBD], IFN sensitivity-determining region [ISDR], and variable region 3 [V3]) were analyzed for the pretreatment serum samples of 60 HCV genotype 1-infected patients treated with pegylated IFN plus ribavirin (1b, n = 47; 1a, n = 13) but with different treatment outcomes, those with sustained virologic responses (SVR; n = 36) or nonresponders (NR; n = 24). Additionally, the sequence of the PKR/eIF-2alpha phosphorylation homology domain (E2-PePHD) region was determined for 23 patients (11 SVR and 12 NR). The presence of > 4 mutations in the PKRBD region was associated with SVR (P = 0.001) and early virologic responses (EVR; 12 weeks) (P = 0.037) but not rapid virologic responses (4 weeks). In the ISDR, the difference was almost statistically significant (68% of SVR patients with mutations versus 45% without mutations; P = 0.07). The V3 region had a very high genetic variability, but this was not related to SVR. Finally, the E2-PePHD (n = 23) region was well conserved. The presence of > 4 mutations in the PKRBD region (odds ratio [OR] = 9.9; P = 0.006) and an age of < or = 40 years (OR = 3.2; P = 0.056) were selected in a multivariate analysis as predictive factors of SVR. NS5A sequences from serum samples taken after 1 month of treatment and posttreatment were examined for 3 SVR and 15 NR patients to select treatment-resistant viral subpopulations, and it was found that in the V3 and flanking regions, the mutations increased significantly in posttreatment sera (P = 0.05). The genetic variability in the PKRBD (> 4 mutations) is a predictive factor of SVR and EVR in HCV genotype 1 patients treated with pegylated IFN and ribavirin.
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24
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Motazakker M, Preikschat P, Elliott J, Smith CA, Mills PR, Oien K, Spence E, Elliott RM, McCruden EAB. Translation efficiencies of the 5'-untranslated region of genotypes 1a and 3a in hepatitis C infected patients. J Med Virol 2007; 79:259-69. [PMID: 17245719 DOI: 10.1002/jmv.20794] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Differences between the translation efficiencies mediated by the 5'-untranslated regions (5'-UTR) of genotypes (gt) 1 and 3 of hepatitis C virus (HCV) have been reported but it is unknown if such differences are biologically significant. The 5'-UTR was sequenced from paired serum and liver samples from 26 patients with chronic HCV hepatitis (11 gt 1a, 15 gt 3a). To determine whether there is a consistent difference between gts 1a and 3a translation efficiency, 5'-UTR (nt 1-356) and 5'-UTR plus core (nt 1-914) sequences were cloned into bicistronic, luciferase-encoding constructs and relative translation efficiencies (RTE) measured in Huh7 cells and BHK cells. The relationships between viral load, liver biopsy Ishak scores, degree of steatosis and translational activity of the patient-derived nucleotide sequence were examined. There were no differences in 5'-UTR sequence between serum and corresponding liver samples. The mean RTE of 5'-UTR sequences from gt 3a isolates was not significantly different from gt 1a whether or not the core encoding sequence was included, although inclusion of core led to a reduction in RTE by 93-97% for both genotypes. No correlation was found between RTE and serum HCV RNA levels, liver steatosis, inflammation, or fibrosis. However, a significant correlation was found between the presence of steatosis and infection with HCV gt 3a. It is concluded that there was no difference in translation efficiencies of 5'-UTRs from patients infected with gts 1a and 3a, and translation activity measured in vitro does not correlate with viral load or severity of liver disease.
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Affiliation(s)
- M Motazakker
- Division of Infection and Immunity, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
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25
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Thélu MA, Leroy V, Ramzan M, Dufeu-Duchesne T, Marche P, Zarski JP. IRES complexity before IFN-alpha treatment and evolution of the viral load at the early stage of treatment in peripheral blood mononuclear cells from chronic hepatitis C patients. J Med Virol 2007; 79:242-53. [PMID: 17245718 DOI: 10.1002/jmv.20792] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
At the early stage of treatment, IFN alpha-2a induces inhibition of HCV replication. The viral load reflects mainly the degradation rate of the viruses. However, differences in the behavior of the viral population depend on changes, which occurred in the HCV-IRES genome. In this study, cloning and sequencing strategies permitted the generation of a large number of IRES sequences from the PBMCs of 18 patients (5 women, 13 men) with chronic hepatitis C. The HCV IRES appeared to be highly conserved structurally. However, some variability was found between the different isolates obtained: 467 substitutions with a median of 7 variants/patients. No relationship was observed between pre-treatment IRES complexity and the viral load at the beginning. However, on review of the evolution of viral load in the PBMCs during the first 3 days of IFN alpha-2a treatment, patients could be classified into two groups: Group 1, in which the viral population continued to replicate and Group 2, in which the viral load decreased significantly (P = 0.01727). Positioning of the mutations on the predicted IRES secondary structure showed that the distribution of the mutations and their apparition frequency were different between the two groups. At the early stage of treatment, IFN alpha-2a was efficient in reducing the viral replication in a significant number of patients; mechanisms of response might affect the virus directly. However, pre-treatment genomic variations observed in the 5'NCR of HCV were not a parameter of a later response to antiviral therapy in chronic hepatitis C patients. (244)
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Affiliation(s)
- M A Thélu
- Département d'Hépato-Gastroentérologie, Hôpital Albert Michallon, Grenoble, France
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26
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Chevaliez S, Bouvier-Alias M, Brillet R, Pawlotsky JM. Overestimation and underestimation of hepatitis C virus RNA levels in a widely used real-time polymerase chain reaction-based method. Hepatology 2007; 46:22-31. [PMID: 17525931 DOI: 10.1002/hep.21656] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
UNLABELLED The quantification of hepatitis C virus (HCV) RNA is essential for the everyday management of chronic hepatitis C therapy. Real-time polymerase chain reaction (PCR) techniques are potentially more sensitive than classical PCR techniques, are not prone to carryover contamination, and have a consistently wider dynamic range of quantification. Thus, they are rapidly replacing other technologies for the routine quantification of HCV RNA. We extensively evaluated the intrinsic characteristics and clinical performance of Cobas Ampliprep/Cobas TaqMan (CAP/CTM), the most widely used real-time PCR assay for HCV RNA quantification. This study shows that CAP/CTM is sensitive, specific, precise, and reproducible and has a broad dynamic range of quantification well suited to HCV RNA monitoring in clinical practice. However, we identified 2 technical issues that will have an impact in clinical practice. First, the CAP/CTM assay overestimates HCV RNA levels in undiluted patient samples by approximately 0.6 log(10) international units per milliliter on average, and this overestimation increases with the viral load. Second, the CAP/CTM assay substantially underestimates HCV RNA levels in approximately 15% of genotype 2 samples and 30% of genotype 4 samples, probably because of mismatches with the target sequences due to the primer and/or probe design. CONCLUSION As the CAP/CTM platform is widely available, easy to use, and suited to high-throughput screening for viral genomes, the manufacturer should improve the HCV RNA kit to resolve these 2 important technical issues that may affect everyday management of hepatitis C therapy.
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Affiliation(s)
- Stéphane Chevaliez
- French National Reference Center for Viral Hepatitis B, C, and Delta, Department of Virology, Hôpital Henri Mondor, Créteil, France
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27
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Abstract
Hepatitis C virus (HCV) behaves as an evolving viral quasispecies in its continuously changing environment. The study of HCV quasispecies population dynamics in experimental models and infected patients can provide useful information on factors involved in the HCV life cycle and pathogenicity. HCV quasispecies variability also has therapeutic implications, as the continuous generation and selection of fitter or truly resistant variants can allow the virus to escape control by antiviral drugs.
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Affiliation(s)
- J M Pawlotsky
- Service de Virologie, Hôpital Henri Mondor, 51 avenue du Maréchal de Lattre de Tassigny, 94010 Créteil, France.
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28
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Gupta R, Subramani M, Khaja MN, Madhavi C, Roy S, Habibullah CM, Das S. Analysis of mutations within the 5' untranslated region, interferon sensitivity region, and PePHD region as a function of response to interferon therapy in hepatitis C virus-infected patients in India. J Clin Microbiol 2006; 44:709-15. [PMID: 16517843 PMCID: PMC1393096 DOI: 10.1128/jcm.44.3.709-715.2006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2005] [Revised: 11/21/2005] [Accepted: 12/06/2005] [Indexed: 12/16/2022] Open
Abstract
Mutations in several subgenomic regions have been implicated in influencing response to interferon therapy; however, a comprehensive picture of Indian patients was lacking. Based on the viral load and clinical factors, 10 out of 15 patients were found to be complete responders, whereas 5 patients were nonresponders. The pretreatment viral RNA load of the patients was found to be between 5.20 and 6.13 log10 IU/ml, which eventually fell to 2.77 log10 IU/ml after 24 weeks of treatment, whereas in the case of nonresponders, the average was 5.38 log10 IU/ml. In order to study the influence of the hepatitis C virus genotype on the response to interferon therapy, the 5' untranslated region sequences of the samples were analyzed, which showed that genotype 3 patients responded better than genotype 1 patients. Additionally, the mutations in the interferon sensitivity-determining region (ISDR) of the NS5A protein and the double-stranded RNA-activated protein kinase-eukaryotic initiation factor 2 alpha phosphorylation homology domain (PePHD) of the E2 envelope protein, before and after treatment, were compared with nonresponder prototype J. Although, no clear correlation was found in the case of the mutated ISDR, some significant changes in residues were observed in the PePHD region, which could be helpful in understanding the molecular basis of resistance to therapy. Interestingly, analysis of the quasispecies variations showed a change in genotype in one sample during treatment, which might have contributed to the resistance. The results suggest that the mutations in different regions of the viral genome might have a concerted effect on the response to interferon therapy.
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Affiliation(s)
- Romi Gupta
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore-560012, India
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29
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Vallejo A, Molina-Pinelo S, Abad MA, Gómez G, Leal M, Sánchez-Quijano A, Lissen E. Analysis of quasispecies in the viral 5' untranslated region of hepatitis C virus to evaluate ribavirin mutagenic effect in patients receiving ribavirin and interferon-alfa. Eur J Clin Microbiol Infect Dis 2005; 23:923-6. [PMID: 15599656 DOI: 10.1007/s10096-004-1238-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In the study presented here the ribavirin mutagenic effect was investigated by analyzing quasispecies in the viral 5' untranslated region of hepatitis C virus in six patients with chronic infection who started interpheron-alpha and ribavirin therapy. A remarkable mutation rate during treatment was found in only one individual. This patient had a sustained response and harbored a type 3a virus strain. The different mutated clones in this patient demonstrated no apparent close relationship that could suggest lack of selection pressure by ribavirin. The mutations were located within the loops of subdomains IIIb and IIId of the internal ribosomal entry site. This is an interesting initial finding that needs to be substantiated in a larger trial.
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Affiliation(s)
- A Vallejo
- Viral Hepatitis and AIDS Study Group, Hospital Universitario Virgen del Rocio, Seville, Spain.
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30
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Vuillermoz I, Khattab E, Sablon E, Ottevaere I, Durantel D, Vieux C, Trepo C, Zoulim F. Genetic variability of hepatitis C virus in chronically infected patients with viral breakthrough during interferon-ribavirin therapy. J Med Virol 2005; 74:41-53. [PMID: 15258967 DOI: 10.1002/jmv.20144] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Little is known about hepatitis C virus (HCV) breakthrough during antiviral therapy, although it would help in understanding HCV resistance to current antiviral treatments. To analyse the implication of virological factors and the vigour of humoral immune responses in this phenomenon, we studied nine chronic hepatitis C patients with a viral breakthrough during IFN/ribavirin combination therapy, as well as five responders and five non-responders. The IRES and regions coding for the capsid protein, the PePHD domain of envelope glycoprotein E2 and the NS5A and 5B proteins were amplified by RT-PCR before treatment, before and during breakthrough, and after treatment. The major variant sequence was obtained by direct sequencing. The heterogeneity of quasispecies was studied by SSCP in all patients and sequencing after cloning in seven genotype 1b-infected patients. Humoral responses against HCV epitopes were also analysed. The major sequences of IRES, PePHD, and NS5B remained stable during treatment, regardless of the treatment response. However, the capsid protein and the regions flanking PePHD showed sequence variations in breakthrough patients, although no specific mutation was identified. The variable V3 region of NS5A, but not the PKR-binding domain and the ISDR, seemed to be associated with differences in response to treatment. The analysis of HCV quasispecies revealed no characteristic pattern during treatment in breakthrough patients, whose HCV genome profiles looked most similar to that of non-responders. The humoral response was similar between groups. In conclusion, viral breakthrough does not seem to be due to selection of resistant strains with signature mutations.
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Affiliation(s)
- I Vuillermoz
- INSERM UNIT 271, 151 Cours Albert Thomas, Lyon, France
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31
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Liu Z, Netski DM, Mao Q, Laeyendecker O, Ticehurst JR, Wang XH, Thomas DL, Ray SC. Accurate representation of the hepatitis C virus quasispecies in 5.2-kilobase amplicons. J Clin Microbiol 2004; 42:4223-9. [PMID: 15365015 PMCID: PMC516368 DOI: 10.1128/jcm.42.9.4223-4229.2004] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Hepatitis C virus (HCV) exists as a swarm of genetically distinct but related variants, or a quasispecies, whose complexity and sequence evolution are critical to studies of viral pathogenesis. Because most studies of the HCV quasispecies have focused on a relatively small genomic segment, the first hypervariable region of the E2 gene, it is possible that viral complexity is occasionally underestimated (due to primer mismatch) and that sequence evolution is misperceived due to unrecognized covariation. This report describes a sensitive and reproducible method to amplify most of the HCV genome as a single 5.2-kb amplicon by using primers directed at relatively conserved genomic segments. Using 52 specimens obtained during acute infection over a range of viral RNA concentrations, the overall rate of successful amplification was 94% and varied in a concentration-dependent manner, with successful amplification in 26 of 26 (100%) specimens at greater than 10(5) IU/ml, 15 of 16 (94%) at 10(4) to 10(5) IU/ml, 6 of 7 (86%) at 10(3) to 10(4) IU/ml, and 2 of 3 (67%) at less than 10(3) IU/ml. Quasispecies complexity, determined by using this novel long-amplicon method followed by heteroduplex mobility assay combined with single-stranded conformational polymorphism (HDA+SSCP) analysis, was very high, even during acute HCV infection, when 10 to 21 (median, 16) different HDA+SSCP patterns were detected among 33 cDNA clones examined. Replicate analyses indicate that this diversity is not dominated by random errors generated during amplification. Therefore, the HCV quasispecies is highly complex even during acute infection and is accurately represented in amplicons representing more than half of the viral genome.
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Affiliation(s)
- Zhi Liu
- Department of Medicine, Johns Hopkins Medical Institutions, Baltimore, Maryland, USA
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32
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Furusyo N, Kubo N, Nakashima H, Kashiwagi K, Etoh Y, Hayashi J. Confirmation of nosocomial hepatitis C virus infection in a hemodialysis unit. Infect Control Hosp Epidemiol 2004; 25:584-90. [PMID: 15301031 DOI: 10.1086/502443] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVES To investigate a hepatitis C virus (HCV) outbreak in a hemodialysis unit and determine the source of transmission. METHODS We have prospectively investigated the epidemiology of hemodialysis-related HCV infection in a single unit since 1989. In September 2000, acute hepatitis C (AH-C) was diagnosed in 5 patients by alanine aminotransferase elevation and HCV genotype 1b viremia without antibody to HCV. We surveyed the epidemiologic situation and performed polymerase chain reaction sequence analysis of the HCV 5'-noncoding (5'NC) region in the patients for comparison with 9 patients with chronic HCV genotype 1b viremia. RESULTS Sequence analysis of the 5'NC region showed the consistency in the 5 independent clones from each AH-C patient and those from each chronic HCV viremia patient and no quasispecies over time in the clones of any of 14 analyzed patients. All AH-C patients had the same sequencing of the 6 variations in the region with the only other patient. A saline ampoule, used for heparin solution during hemodialysis, had a recap function. It was difficult to determine whether the ampoule was new or had already been used. The source-patient often underwent hemodialysis before the AH-C patients and most of their hemodialysis-related medicine was prepared during the source-patient's treatment. These findings suggested a high possibility that the AH-C patients shared a single heparin-saline solution ampoule contaminated by HCV from the source-patient. CONCLUSION Nosocomial HCV infection occurred as a result of poor infection control practice when a patient with chronic HCV viremia received treatment prior to other hemodialysis patients.
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Affiliation(s)
- Norihiro Furusyo
- Department of General Medicine, Kyushu University Hospital, Higashi-Ku, Fukuoka, Japan
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Soler M, McHutchison JG, Kwoh TJ, Dorr FA, Pawlotsky JM. Virological Effects of Isis 14803, An Antisense Oligonucleotide Inhibitor of Hepatitis C Virus (HCV) Internal Ribosome Entry Site (IRES), on HCV Ires in Chronic Hepatitis C Patients and Examination of the Potential Role of Primary and Secondary HCV Resistance in the Outcome of Treatment. Antivir Ther 2004. [DOI: 10.1177/135965350400900612] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Antisense oligonucleotides represent a promising class of antiviral agents. ISIS 14803 is a 20-unit phosphorothioate oligodeoxynucleotide that inhibited hepatitis C virus (HCV) replication and protein expression in cell culture and mouse models. A Phase I dose-escalation clinical study of ISIS 14803 was performed in 24 patients with HCV genotype 1 chronic hepatitis C. The patients received 0.5, 1.0, 2.0 or 3.0 mg/kg of ISIS 14803 for 4 weeks. Two of them receiving 2.0 mg/kg, experienced a significant (>1.0 log10) viral load reduction and nine other patients experienced minor (<1.0 log10) viral load reductions that were difficult to definitively distinguish from assay or patient variations. The aims of this study were to examine the effect of ISIS 14803 on its target site and neighbouring region quasispecies evolution, and to determine whether primary and secondary HCV resistance contributed to the observed virological response rate. The HCV internal ribosome entry site (IRES), including the ISIS 14803 target site in virus specimens collected from patients at baseline and end-of-treatment, was sequenced. An extensive IRES quasispecies analysis was performed in 10 of the patients at various time points before, during and after ISIS 14803 treatment. A significant IRES genetic evolution was found in three out of 10 patients through quasispecies analysis suggesting that treatment with ISIS 14803, a drug designed to bind to HCV RNA, exerted a selective pressure on HCV IRES. However, no mutations in the ISIS 14803 target site, which would inhibit binding of the oligonucleotide to HCV RNA, were detected before (primary resistance) or after treatment (secondary resistance) with the oligonucleotide. Furthermore, no obvious nucleotide changes in the surrounding IRES region that might possibly affect oligonucleotide binding were detected.
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Affiliation(s)
- Muriel Soler
- Department of Virology, INSERM U635, Henri Mondor Hospital, University of Paris XII, Créteil, France
| | - John G McHutchison
- Duke Clinical Research Institute, Duke University Clinical Center, Durham, NC, USA
| | | | | | - Jean-Michel Pawlotsky
- Department of Virology, INSERM U635, Henri Mondor Hospital, University of Paris XII, Créteil, France
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Radhakrishnan SK, Layden TJ, Gartel AL. RNA interference as a new strategy against viral hepatitis. Virology 2004; 323:173-81. [PMID: 15193913 DOI: 10.1016/j.virol.2004.02.021] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 02/03/2004] [Accepted: 02/19/2004] [Indexed: 12/11/2022]
Abstract
Hepatitis viruses are the leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. Since currently available treatment options against these viruses are limited, there is a need for development of alternative therapies. In this minireview, we concentrate on three hepatitis viruses--hepatitis C virus, hepatitis B virus, and hepatitis delta virus and discuss how RNA interference (RNAi) has been utilized against them. RNAi is a process by which small double-stranded RNA can effectively target a homologous RNA sequence for degradation by cellular ribonucleases. Though RNAi was exploited in the beginning for down-regulating cellular genes, it has recently been demonstrated that this process is equally effective against many types of human and animal viruses including the hepatitis viruses. Both synthetic small-interfering RNAs (siRNAs) and plasmid-based siRNA expression systems have been useful in suppressing the hepatitis viruses. Though this new approach looks promising, problems of nonspecific effects and delivery may need to be addressed before the full therapeutic potential of RNAi against viral infections in patients is realized.
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Forton DM, Karayiannis P, Mahmud N, Taylor-Robinson SD, Thomas HC. Identification of unique hepatitis C virus quasispecies in the central nervous system and comparative analysis of internal translational efficiency of brain, liver, and serum variants. J Virol 2004; 78:5170-83. [PMID: 15113899 PMCID: PMC400349 DOI: 10.1128/jvi.78.10.5170-5183.2004] [Citation(s) in RCA: 193] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Reports of cerebral dysfunction in chronic hepatitis C virus (HCV) infection have led to the suggestion that HCV may infect the central nervous system (CNS). We used reverse transcription-PCR, cloning, and sequencing to define quasispecies for the HCV internal ribosomal entry site (IRES) and hypervariable region 1 (HVR1) in autopsy-derived brain, liver, lymph node, and serum samples. There was evidence of tissue compartmentalization of sequences in the brain in two patients, with between 24 and 55% of brain-derived IRES sequences absent from the serum, and significant phylogenetic and phenetic clustering of the brain and lymph node HVR1 sequences. The IRES initiates cap-independent translation of the viral polyprotein. Two unique brain-derived IRES mutations (C(204)-->A and G(243)-->A), which have previously been associated with lymphoid replication and altered translational efficiency in cell culture, were found in one patient. We used a dicistronic reporter vector to test whether brain-derived variants showed altered IRES-mediated translational efficiency, which might favor CNS infection. The translational efficiencies of the brain-derived IRES sequences were generally reduced compared to those of the master serum and liver sequences in rabbit reticulocyte cell lysates and two human cell lines, HuH7 (liver) and CHME3 (microglial). The C(204)-->A and G(243)-->A mutations showed preserved translational efficiency in HuH7 cells but reduced efficiency in CHME3 cells. Our data provide evidence that the CNS is a site of HCV replication, consistent with the recent demonstration of negative-strand HCV RNA in brain, and suggest that IRES polymorphisms may be important as a viral strategy of reduced translation to favor latency in the CNS.
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Affiliation(s)
- Daniel M Forton
- Hepatology Section, Division of Medicine, Faculty of Medicine, Imperial College London, 10th Floor, QEQM Building, St. Mary's Hospital, South Wharf Road, London W2 1NY, United Kingdom.
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Thelu MA, Drouet E, Hilleret MN, Zarski JP. Lack of clinical significance of variability in the internal ribosome entry site of hepatitis C virus. J Med Virol 2004; 72:396-405. [PMID: 14748063 DOI: 10.1002/jmv.20021] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The extreme 5'-proximal sequence of the hepatitis C virus (HCV) genome including the 5' non-coding region (5'NCR) of 341 nucleotide long and the first 30 nucleotides of the core region is highly conserved among different HCV genotypes. It contains a segment termed Internal Ribosome Entry Site (IRES) that regulates the cap-independent translation of HCV-RNA to polyprotein. Sequence variability in this region has important implications for structural organisation and function of the IRES element and could correlate with HCV RNA concentration or response to antiviral therapy. Fourteen patients (seven women, seven men) with chronic hepatitis C were separated into two groups according to their response to antiviral therapy. Seven of these were sustained responders to treatment by Interferon alpha 2b and Ribavirin and seven were non-responders. After cloning-sequencing, the IRES (nt 21 to 374) appears to be structurally highly conserved. However some variability was found between the different isolates obtained: 209 substitutions with a median of four variants/patients. Comparison of the number of variants present in the viral population of the sustained responders and non-responders patients do not show any difference. Positioning of the mutations on the predicted IRES secondary structure showed that the distribution of the mutations and their apparition frequency were different between the two groups. The translation initiator AUG-4 codon, located in the stem-loop IV, is never modified. Variations observed in the IRES are not a parameter of response to antiviral therapy, but the integrity of this region is a necessary condition to maintain its activity.
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Affiliation(s)
- Marie-Ange Thelu
- Département d'Hépato-Gastroentérologie, Hôpital Albert Michallon, Grenoble, France.
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Löve A, Molnegren V, Månsson AS, Smáradóttir A, Thorsteinsson SB, Widell A. Evolution of hepatitis C virus variants following blood transfusion from one infected donor to several recipients: a long-term follow-up. J Gen Virol 2004; 85:441-450. [PMID: 14769902 DOI: 10.1099/vir.0.19439-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Variants of hepatitis C virus (HCV) from a single infected blood donor and 13 viraemic recipients who were traced were examined by sequencing and cloning to determine the extent of virus diversity in hypervariable region 1. Serum-derived viral isolates were studied from the donor when his HCV infection was discovered in 1993, in his recipients that year (0.3-5 years post-transfusion) and 5 years later in the donor and six viraemic recipients who were still alive. Viral variants of broad diversity were readily demonstrated in the baseline samples of the donor (nucleotide p-distance 0.130), but significantly less (P<0.00003) diversity was observed in the recipients' first samples (p-distances within recipients 0.003-0.062). In the first blood samples of the recipients, many of the viral variants identified were closely related to a strain variant from the donor. In follow-up samples drawn 5 years later from the donor and six recipients, the p-distance among donor clones had increased (0.172, P<0.0005) compared with the recipients, who displayed significantly narrower quasispecies (0.011-0.086). A common finding was that recipients of blood components processed from the same donation differed substantially in persisting HCV infectious sequence. Markedly few changes leading to changes of amino acids had occurred during follow-up in four of six recipients. These results question the significance of the development of viral variants as a necessary phenomenon in the evolution of HCV and pathogenesis of the disease.
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Affiliation(s)
- Arthur Löve
- Department of Medical Virology, Landspitali-University Hospital, University of Iceland, Reykjavik, Iceland
| | - Vilma Molnegren
- Department of Medical Microbiology, Malmö University Hospital, Lund University, SE-20502 Malmö, Sweden
| | - Ann-Sofie Månsson
- Department of Medical Microbiology, Malmö University Hospital, Lund University, SE-20502 Malmö, Sweden
| | - Agnes Smáradóttir
- Department of Internal Medicine, Landspitali-University Hospital, University of Iceland, Reykjavik, Iceland
| | - Sigurdur B Thorsteinsson
- Department of Internal Medicine, Landspitali-University Hospital, University of Iceland, Reykjavik, Iceland
| | - Anders Widell
- Department of Medical Microbiology, Malmö University Hospital, Lund University, SE-20502 Malmö, Sweden
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Kalaycio M. Hematopoietic growth factors for acute myelogenous leukemia. CURRENT HEMATOLOGY REPORTS 2004; 3:38-9. [PMID: 14695848 DOI: 10.1007/s11901-004-0007-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
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Novella IS. Contributions of vesicular stomatitis virus to the understanding of RNA virus evolution. Curr Opin Microbiol 2003; 6:399-405. [PMID: 12941412 DOI: 10.1016/s1369-5274(03)00084-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Vesicular stomatitis virus has been a preferred system to study evolution for several decades. New approaches to antiviral treatment, such as lethal mutagenesis, stem from investigations done with VSV. Recent work has shed new light in the way we view neutrality, a fundamental concept to understand the evolutionary history of RNA viruses.
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Affiliation(s)
- Isabel S Novella
- Department of Microbiology and Immunology, Medical College of Ohio, 3055 Arlington Ave., Toledo 43614, OH, USA.
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Vyas J, Elia A, Clemens MJ. Inhibition of the protein kinase PKR by the internal ribosome entry site of hepatitis C virus genomic RNA. RNA (NEW YORK, N.Y.) 2003; 9:858-870. [PMID: 12810919 PMCID: PMC1370452 DOI: 10.1261/rna.5330503] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2003] [Accepted: 04/10/2003] [Indexed: 05/24/2023]
Abstract
Translation of the hepatitis C genome is mediated by internal ribosome entry on the structurally complex 5' untranslated region of the large viral RNA. Initiation of protein synthesis by this mechanism is independent of the cap-binding factor eIF4E, but activity of the initiator Met-tRNA(f)-binding factor eIF2 is still required. HCV protein synthesis is thus potentially sensitive to the inhibition of eIF2 activity that can result from the phosphorylation of the latter by the interferon-inducible, double-stranded RNA-activated protein kinase PKR. Two virally encoded proteins, NS5A and E2, have been shown to reduce this inhibitory effect of PKR by impairing the activation of the kinase. Here we present evidence for a third viral strategy for PKR inhibition. A region of the viral RNA comprising part of the internal ribosome entry site (IRES) is able to bind to PKR in competition with double-stranded RNA and can prevent autophosphorylation and activation of the kinase in vitro. The HCV IRES itself has no PKR-activating ability. Consistent with these findings, cotransfection experiments employing a bicistronic reporter construct and wild-type PKR indicate that expression of the protein kinase is less inhibitory towards HCV IRES-driven protein synthesis than towards cap-dependent protein synthesis. These data suggest a dual function for the viral IRES, with both a structural role in promoting initiation complex formation and a regulatory role in preventing inhibition of initiation by PKR.
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Affiliation(s)
- Jashmin Vyas
- Translational Control Group, Department of Basic Medical Sciences, St. George's Hospital Medical School, London SW17 0RE, UK
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Abstract
The treatment of chronic hepatitis C is currently based on a combination of pegylated interferon (IFN)-alpha and ribavirin. When successful, this treatment leads to sustained HCV clearance which, in virtually all cases, signifies viral eradication. However, approximately 20% of patients with hepatitis C virus (HCV) genotype 2 or 3 infection, and 50% of patients with genotype 1 infection, fail to eradicate the virus. The risk of treatment failure is related to multiple factors, including the treatment schedule, adherence of therapy, host factors, and the severity of HCV-associated disease. Viral factors can also lead to true "HCV resistance". The mechanisms underlying this resistance are unknown, but indirect evidence suggests that chronic infection is associated with phenomena that protect HCV from the antiviral action of IFN-alpha and hinder the clearance of infected cells. This article discusses current knowledge of the mechanisms of action of IFN-alpha and ribavirin, the virological characteristics of chronic hepatitis C treatment success and failure, and possible underlying mechanisms.
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Affiliation(s)
- Jean Michel Pawlotsky
- Department of Virology (EA 3489), Hôpital Henri Mondor, Université Paris XII, 51 Avenue du Maréchal de Lattre de Tassigny, 94010, Créteil, France.
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Liang XS, Lian JQ, Zhou YX, Nie QH, Hao CQ. A small yeast RNA inhibits HCV IRES mediated translation and inhibits replication of poliovirus in vivo. World J Gastroenterol 2003; 9:1008-13. [PMID: 12717847 PMCID: PMC4611363 DOI: 10.3748/wjg.v9.i5.1008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the anti-virus infection activity of internal ribosome entry site (IRES) specific inhibitor RNA (IRNA).
METHODS: IRNA eukaryotic vector pcRz-IRNA or mIRNA eukaryotic vector pcRz-mIRNA was tansfected into human hepatocarcinoma cells (HHCC), then selected with neomycin G418 for 4 to 8 weeks, and then infected with polio virus vaccinas line. The cytopethogenesis effect was investigated and the cell extract was collected. At last the polio virus titer of different cells was determined by plaque assay.
RESULTS: Constitutive expression of IRNA was not detrimental to cell growth. HCV IRES-mediated cap-independent translation was markedly inhibited in cells constitutively expressing IRNA compared to control hepatoma cells. However, cap-dependent translation was not significantly affected in these cell line. Additionally, HHCC cells constitutively expressing IRNA became refractory to infection of polio virus.
CONCLUSION: IRES specific IRNA can inhibit HCV IRES mediated translation and poliovirus replication.
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Affiliation(s)
- Xue-Song Liang
- The center of diagnosis and treatment for infectious diseases of Tangdu Hospital of Military Medical University of PLA, Xi'an. 710038, Shaanxi Province, China
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N/A. N/A. Shijie Huaren Xiaohua Zazhi 2003; 11:242-245. [DOI: 10.11569/wcjd.v11.i2.242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Abstract
HCV is variable because of the properties of the viral RdRp, high levels of replication, and large population sizes. The Darwinian evolution of HCV has been characterized by the emergence of the HCV genotypes, including six main types and a large number of subtypes. The study of HCV genotype epidemiology provides useful information on the worldwide HCV epidemics. The HCV genotype is an important predictor of the response to IFN-alpha-based antiviral therapy, and genotype determination is currently used to tailor treatment indications. In addition, HCV circulates and behaves in infected individuals as mixtures of closely related but distinct viral populations referred to as quasispecies. This particular nature of the virus influences its transmission, the pathogenesis of liver disease and extra-hepatic manifestations, and the outcome during and after antiviral therapy or after transplantation for HCV-related end-stage liver disease. Further studies are needed to understand better the implications of HCV quasispecies diversity in the pathophysiology of HCV infection.
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Affiliation(s)
- Jean-Michel Pawlotsky
- Department of Virology (EA 3489), Henri Mondor Hospital, University of Paris XII, 51 avenue du Maréchal de Lattre de Tassigny, Créteil 94010, France.
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