scholarly journals The Cyclophilin Inhibitor SCY-635 Disrupts Hepatitis C Virus NS5A-Cyclophilin A Complexes

2012 ◽  
Vol 56 (7) ◽  
pp. 3888-3897 ◽  
Author(s):  
Sam Hopkins ◽  
Michael Bobardt ◽  
Udayan Chatterji ◽  
Jose A. Garcia-Rivera ◽  
Precious Lim ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Replication ◽  
Cyclophilin A ◽  
Hcv Rna ◽  
Dependent Manner ◽  
Mutant Proteins ◽  
Cypa Binding

ABSTRACTThe nonimmunosuppressive cyclophilin (Cyp) inhibitor SCY-635 blocks hepatitis C virus (HCV) replication bothin vitroandin vivoand represents a novel potent anti-HCV agent. However, its mechanism of action remains to be fully elucidated. A growing body of evidence suggests that cyclophilin A (CypA) is absolutely necessary for HCV replication and that the HCV nonstructural 5A (NS5A) protein serves as a main viral ligand for CypA. In this study, we examined the effect of SCY-635 on HCV replication. Specifically, we asked whether SCY-635 blocks HCV replication by targeting CypA-NS5A interactions. We also investigated the possibility that HCV can escape SCY-635 selection pressure and whether this resistance influences either CypA-NS5A interactions or the dependence of HCV on CypA. We found not only that SCY-635 efficiently inhibits HCV replication, but it is sufficient alone to clear HCV replicon-containing cells. We found that SCY-635 prevents CypA-NS5A interactions in a dose-dependent manner. SCY-635 prevents the contact between CypA and NS5A derived from genotypes 1 to 3. Together, these data suggest that NS5A-CypA interactions control HCV replication and that SCY-635 blocks viral replication by preventing the formation of these complexes. We also found that NS5A mutant proteins found in SCY-635-resistant HCV replicons behave similarly to wild-type NS5A in terms of both CypA binding and SCY-635-mediated dissociation and inhibition of CypA binding. However, the NS5A mutations found in SCY-635-resistant HCV replicons rescued viral replication in CypA-knockdown cells, suggesting that the NS5A mutations, which arosein vitrounder SCY-635 selection, do not alter the binding affinity of CypA for NS5A. These specific mutations in NS5A eliminate the dependence of HCV RNA replication on the expression of host CypA

scholarly journals A role for B cells to transmit hepatitis C virus infection

2020 ◽  
Author(s):  
Isabelle Desombere ◽  
Freya Van Houtte ◽  
Ali Farhoudi ◽  
Lieven Verhoye ◽  
Caroline Buysschaert ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
B Cells ◽  
Neutralizing Antibody ◽  
Hcv Rna ◽  
Serum Samples ◽  
Cell Culture Systems ◽  
Hcv Transmission

Abstract Hepatitis C virus (HCV) is highly variable and transmits through infected blood to establish a chronic liver infection in the majority of patients. Our knowledge of the infectivity of clinical HCV strains is hampered by the lack of in vitro cell culture systems that support efficient viral replication. We previously reported that laboratory strains of HCV associated with non-permissive B cells could trans-infect hepatocytes and thereby evade host neutralizing antibody responses, suggesting a role for B cells in HCV transmission. To evaluate this hypothesis, we assessed the ability of B cells and sera from recent (<2 years) or chronic (≥ 2 years) infections to infect humanized liver chimeric mice. HCV was efficiently transmitted by B cells from chronically infected patients whereas the sera were non-infectious. In contrast, we noted that B cells from recently infected patients failed to transmit HCV to the mice, whereas all serum samples were infectious. Only patients with circulating anti-glycoprotein antibodies harbored genomic HCV-RNA in B cells. Taken together, our studies provide direct in vivo evidence for HCV transmission by B cells and these findings may have clinical implications for prophylactic and therapeutic antibody-based vaccine design.

scholarly journals Hepatitis C Virus Core Protein Interacts with 14-3-3 Protein and Activates the Kinase Raf-1

2000 ◽  
Vol 74 (4) ◽  
pp. 1736-1741 ◽  
Author(s):  
Hiroshi Aoki ◽  
Junpei Hayashi ◽  
Mitsuhiko Moriyama ◽  
Yasuyuki Arakawa ◽  
Okio Hino
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Growth Regulation ◽  
Core Protein ◽  
Dependent Manner ◽  
Kinase Activation ◽  
Virus Core ◽  
Hcv Core Protein

ABSTRACT Persistent hepatitis C virus (HCV) infection is a major cause of chronic liver dysfunction in humans and is epidemiologically closely associated with the development of human hepatocellular carcinoma. Among HCV components, core protein has been reported to be implicated in cell growth regulation both in vitro and in vivo, although mechanisms explaining those effects are still unclear. In the present study, we identified that members of the 14-3-3 protein family associate with HCV core protein. 14-3-3 protein bound to HCV core protein in a phosphoserine-dependent manner. Introduction of HCV core protein caused a substantial increase in Raf-1 kinase activity in HepG2 cells and in a yeast genetic assay. Furthermore, the HCV core–14-3-3 interaction was essential for Raf-1 kinase activation by HCV core protein. These results suggest that HCV core protein may represent a novel type of Raf-1 kinase-activating protein through its interaction with 14-3-3 protein and may contribute to hepatocyte growth regulation.

scholarly journals Production of Infectious Hepatitis C Virus of Various Genotypes in Cell Cultures

2007 ◽  
Vol 81 (9) ◽  
pp. 4405-4411 ◽  
Author(s):  
Takanobu Kato ◽  
Takuya Matsumura ◽  
Theo Heller ◽  
Satoru Saito ◽  
Ronda K. Sapp ◽  
...  
Keyword(s):  
Cell Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Culture Medium ◽  
Expression System ◽  
Core Antigen ◽  
Hcv Rna ◽  
Transfected Cells

ABSTRACT A unique hepatitis C virus (HCV) strain JFH-1 has been shown to replicate efficiently in cell culture with production of infectious HCV. We previously developed a DNA expression system containing HCV cDNA flanked by two self-cleaving ribozymes to generate HCV particles in cell culture. In this study, we produced HCV particles of various genotypes, including 1a (H77), 1b (CG1b), and 2a (J6 and JFH-1), in the HCV-ribozyme system. The constructs also contain the secreted alkaline phosphatase gene to control for transfection efficiency and the effects of culture conditions. After transfection into the Huh7-derived cell line Huh7.5.1, continuous HCV replication and secretion were confirmed by the detection of HCV RNA and core antigen in the culture medium. HCV replication levels of strains H77, CG1b, and J6 were comparable, whereas the JFH-1 strain replicates at a substantially higher level than the other strains. To evaluate the infectivity in vitro, the culture medium of JFH-1-transfected cells was inoculated into naive Huh7.5.1 cells. HCV proteins were detected by immunofluorescence 3 days after inoculation. To evaluate the infectivity in vivo, the culture medium from HCV genotype 1b-transfected cells was inoculated into a chimpanzee and caused a typical course of HCV infection. The HCV 1b propagated in vitro and in vivo had sequences identical to those of the HCV genomic cDNA used for cell culture transfection. The development of culture systems for production of various HCV genotypes provides a valuable tool not only to study the replication and pathogenesis of HCV but also to screen for antivirals.

scholarly journals Interaction with a Ubiquitin-Like Protein Enhances the Ubiquitination and Degradation of Hepatitis C Virus RNA-Dependent RNA Polymerase

2003 ◽  
Vol 77 (7) ◽  
pp. 4149-4159 ◽  
Author(s):  
Lu Gao ◽  
Hong Tu ◽  
Stephanie T. Shi ◽  
Ki-Jeong Lee ◽  
Miyuki Asanaka ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Rna Polymerase ◽  
Hcv Rna ◽  
Rna Dependent Rna Polymerase ◽  
Subgenomic Replicon ◽  
C Terminus ◽  
Huh7 Cells

ABSTRACT To identify potential cellular regulators of hepatitis C virus (HCV) RNA-dependent RNA polymerase (NS5B), we searched for cellular proteins interacting with NS5B protein by yeast two-hybrid screening of a human hepatocyte cDNA library. We identified a ubiquitin-like protein, hPLIC1 (for human homolog 1 of protein linking intergrin-associated protein and cytoskeleton), which is expressed in the liver (M. F. Kleijnen, A. H. Shih, P. Zhou, S. Kumar, R. E. Soccio, N. L. Kedersha, G. Gill, and P. M. Howley, Mol. Cell 6: 409-419, 2000). In vitro binding assays and in vivo coimmunoprecipitation studies confirmed the interaction between hPLIC1 and NS5B, which occurred through the ubiquitin-associated domain at the C terminus of the hPLIC1 protein. As hPLICs have been shown to physically associate with two E3 ubiquitin protein ligases as well as proteasomes (Kleijnen et al., Mol. Cell 6: 409-419, 2000), we investigated whether the stability and posttranslational modification of NS5B were affected by hPLIC1. A pulse-chase labeling experiment revealed that overexpression of hPLIC1, but not the mutant lacking the NS5B-binding domain, significantly shortened the half-life of NS5B and enhanced the polyubiquitination of NS5B. Furthermore, in Huh7 cells that express an HCV subgenomic replicon, the amounts of both NS5B and the replicon RNA were reduced by overexpression of hPLIC1. Thus, hPLIC1 may be a regulator of HCV RNA replication through interaction with NS5B.

scholarly journals Modeling Subgenomic Hepatitis C Virus RNA Kinetics during Treatment with Alpha Interferon

2009 ◽  
Vol 83 (13) ◽  
pp. 6383-6390 ◽  
Author(s):  
Harel Dahari ◽  
Bruno Sainz ◽  
Alan S. Perelson ◽  
Susan L. Uprichard
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Rna ◽  
Alpha Interferon ◽  
Hcv Rna ◽  
Second Phase ◽  
Inhibition Kinetics ◽  
Rna Levels

ABSTRACT Although replicons have been used to demonstrate hepatitis C virus (HCV) inhibition by alpha interferon (IFN-α), the detailed inhibition kinetics required to mathematically model HCV RNA decline have been lacking. Therefore, we measured genotype 1b subgenomic replicon (sg1b) RNA levels under various IFN-α concentrations to assess the inhibition kinetics of intracellular HCV RNA. During nine days of IFN-α treatment, sg1b RNA decreased in a biphasic, dose-dependent manner. Using frequent measurements to dissect these phases during IFN-α treatments of 100 and 250 U/ml revealed that the first-phase sg1b RNA decline began ∼12 h posttreatment, continued for 2 to 4 days, and then exhibited a distinct flat or slower second phase. Based on these data, we developed a mathematical model of IFN-α-induced intracellular sg1b RNA decline, and we show that the mechanism(s) mediating IFN-α inhibition of HCV acts primarily by reducing sg1b RNA amplification, with an additional effect on HCV RNA stability/degradation detectable at a dose of 250 U/ml IFN-α. While the extremely slow or flat second phase of viral RNA inhibition observed in vitro, in which there is little or no cell death, supports the in vivo modeling prediction that the more profound second-phase decline observed in IFN-α-treated patients reflects immune-mediated death/loss of productively infected cells, the second-phase decline in viral RNA with a dose of 250 U/ml IFN-α suggests that a further inhibition of intracellular HCV RNA levels may contribute as well. As such, dissection of HCV IFN-α inhibition kinetics in vitro has brought us closer to understanding the mechanism(s) by which IFN-α may be inhibiting HCV in vivo.

scholarly journals Biochemical Characterization of the Active Anti-Hepatitis C Virus Metabolites of 2,6-Diaminopurine Ribonucleoside Prodrug Compared to Sofosbuvir and BMS-986094

2016 ◽  
Vol 60 (8) ◽  
pp. 4659-4669 ◽  
Author(s):  
Maryam Ehteshami ◽  
Sijia Tao ◽  
Tugba Ozturk ◽  
Longhu Zhou ◽  
Jong Hyun Cho ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Biochemical Characterization ◽  
Nonstructural Protein ◽  
Nucleoside Triphosphate ◽  
Hcv Rna ◽  
Mitochondrial Rna ◽  
Active Metabolites

ABSTRACTRibonucleoside analog inhibitors (rNAI) target the hepatitis C virus (HCV) RNA-dependent RNA polymerase nonstructural protein 5B (NS5B) and cause RNA chain termination. Here, we expand our studies on β-d-2′-C-methyl-2,6-diaminopurine-ribonucleotide (DAPN) phosphoramidate prodrug 1 (PD1) as a novel investigational inhibitor of HCV. DAPN-PD1 is metabolized intracellularly into two distinct bioactive nucleoside triphosphate (TP) analogs. The first metabolite, 2′-C-methyl-GTP, is a well-characterized inhibitor of NS5B polymerase, whereas the second metabolite, 2′-C-methyl-DAPN-TP, behaves as an adenosine base analog.In vitroassays suggest that both metabolites are inhibitors of NS5B-mediated RNA polymerization. Additional factors, such as rNAI-TP incorporation efficiencies, intracellular rNAI-TP levels, and competition with natural ribonucleotides, were examined in order to further characterize the potential role of each nucleotide metabolitein vivo. Finally, we found that although both 2′-C-methyl-GTP and 2′-C-methyl-DAPN-TP were weak substrates for human mitochondrial RNA (mtRNA) polymerase (POLRMT)in vitro, DAPN-PD1 did not cause off-target inhibition of mtRNA transcription in Huh-7 cells. In contrast, administration of BMS-986094, which also generates 2′-C-methyl-GTP and previously has been associated with toxicity in humans, caused detectable inhibition of mtRNA transcription. Metabolism of BMS-986094 in Huh-7 cells leads to 87-fold higher levels of intracellular 2′-C-methyl-GTP than DAPN-PD1. Collectively, our data characterize DAPN-PD1 as a novel and potent antiviral agent that combines the delivery of two active metabolites.

scholarly journals Cyclophilin A Is an Essential Cofactor for Hepatitis C Virus Infection and the Principal Mediator of Cyclosporine Resistance In Vitro

2008 ◽  
Vol 82 (11) ◽  
pp. 5269-5278 ◽  
Author(s):  
Feng Yang ◽  
Jason M. Robotham ◽  
Heather B. Nelson ◽  
Andre Irsigler ◽  
Rachael Kenworthy ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Cyclophilin A ◽  
Hcv Rna ◽  
Wild Type ◽  
Replication Assay ◽  
Cellular Cofactor ◽  
Interfering Rna ◽  
Cypa Expression

ABSTRACT Cyclosporine (CsA) and its derivatives potently suppress hepatitis C virus (HCV) replication. Recently, CsA-resistant HCV replicons have been identified in vitro. We examined the dependence of the wild-type and CsA-resistant replicons on various cyclophilins for replication. A strong correlation between CsA resistance and reduced dependency on cyclophilin A (CyPA) for replication was identified. Silencing of CyPB or CyPC expression had no significant effect on replication, whereas various forms of small interfering RNA (siRNA) directed at CyPA inhibited HCV replication of wild-type but not CsA-resistant replicons. The efficiency of a particular siRNA in suppressing CyPA expression was correlated with its potency in inhibiting HCV replication, and expression of an siRNA-resistant CyPA cDNA rescued replication. In addition, an anti-CyPA antibody blocked replication of the wild-type but not the resistant replicon in an in vitro replication assay. Depletion of CyPA alone in the CsA-resistant replicon cells eliminated CsA resistance, indicating that CyPA is the chief mediator of the observed CsA resistance. The dependency on CyPA for replication was observed for both genotype (GT) 1a and 1b replicons as well as a GT 2a infectious virus. An interaction between CyPA and HCV RNA as well as the viral polymerase that is sensitive to CsA treatment in wild-type but not in resistant replicons was detected. These findings reveal the molecular mechanism of CsA resistance and identify CyPA as a critical cellular cofactor for HCV replication and infection.

Funktion von CEACAM-1 im Rahmen der Therapie der Hepatitis C-Virus Infektion mit Interferon-alpha in vivo und in vitro

2006 ◽  
Vol 44 (08) ◽  
Author(s):  
P Hilgard ◽  
R Bröring ◽  
M Trippler ◽  
S Viazov ◽  
G Gerken ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Interferon Alpha

scholarly journals Genotypic and Phenotypic Analyses of Hepatitis C Virus from Patients Treated with JTK-853 in a Three-Day Monotherapy

2012 ◽  
Vol 57 (1) ◽  
pp. 436-444 ◽  
Author(s):  
Naoki Ogura ◽  
Yukiyo Toyonaga ◽  
Izuru Ando ◽  
Kunihiro Hirahara ◽  
Tsutomu Shibata ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Amino Acid ◽  
Viral Resistance ◽  
Hcv Rna ◽  
Amino Acid Substitutions ◽  
Sequencing Analysis ◽  
Resistance Mutations ◽  
In The Wild

ABSTRACTJTK-853, a palm site-binding NS5B nonnucleoside polymerase inhibitor, shows antiviral activityin vitroand in hepatitis C virus (HCV)-infected patients. Here, we report the results of genotypic and phenotypic analyses of resistant variants in 24 HCV genotype 1-infected patients who received JTK-853 (800, 1,200, or 1,600 mg twice daily or 1,200 mg three times daily) in a 3-day monotherapy. Viral resistance in NS5B was investigated using HCV RNA isolated from serum specimens from the patients. At the end of treatment (EOT) with JTK-853, the amino acid substitutions M414T (methionine [M] in position 414 at baseline was replaced with threonine [T] at EOT), C445R (cysteine [C] in position 445 at baseline was replaced with arginine [R] at EOT), Y448C/H (tyrosine [Y] in position 448 at baseline was replaced with cysteine [C] or histidine [H] at EOT), and L466F (leucine [L] in position 466 at baseline was replaced with phenylalanine [F] at EOT), which are known to be typical resistant variants of nonnucleoside polymerase inhibitors, were observed in a clonal sequencing analysis. These substitutions were also selected by a treatment with JTK-853in vitro, and the 50% effective concentration of JTK-853 in the M414T-, C445F-, Y448H-, and L466V-harboring replicons attenuated the susceptibility by 44-, 5-, 6-, and 21-fold, respectively, compared with that in the wild-type replicon (Con1). These findings suggest that amino acid substitutions of M414T, C445R, Y448C/H, and L466F are thought to be viral resistance mutations in HCV-infected patients receiving JTK-853 in a 3-day monotherapy.

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