Decrease In Hepatitis C Virus RNA Research Articles

Hepatitis C Virus Reactivation in Anti-HCV Antibody-Positive Patients with Chronic Hepatitis B Following Anti-HBV Therapies.

Background and Aims: Whether hepatitis C virus (HCV) reactivation occurs and how the viral load evolves in anti-HCV antibody-positive chronic hepatitis B (CHB) patients who underwent nucleos(t)ide analogue (Nuc) therapies remain unsolved. Methods: A cohort of 66 such patients was studied. Results: At the start of Nuc treatment (baseline), all patients had detectable hepatitis B virus (HBV) DNA levels (6.05 ± 1.88 log IU/mL), while HCV RNA levels (3.79 ± 1.43 log IU/mL) were detected (i.e., chronic hepatitis C (CHC)) in only 13 patients (19.7%). Following Nuc therapies, HBV DNA levels reached the nadirs at end of therapy (EOT) (6.05 ± 1.88 vs. 0.25 ± 0.99 log IU/mL, p < 0.0001) and relapsed at 6 months after EOT (6mEOT) at a level of 3.45 ± 2.64 log IU/mL compared with EOT (p < 0.0001). Among the 13 CHC patients, a non-significant decrease in HCV RNA was noted at EOT (3.52 ± 1.71 vs. 2.77 ± 2.63 log IU/mL, p = 0.166) but tended to decrease further at 6mEOT (2.77 ± 2.63 vs. 1.89 ± 2.06 log IU/mL, p = 0.063). Two of the thirteen CHC patients showed an increase in HCV-RNA ≥ 1 log10 IU/mL at EOT, and one of the fifty-three patients with undetectable HCV RNA at baseline (i.e., resolved past HCV infection) showed detectable HCV RNA at year 1 (3200 IU/mL) and year 2 (1240 IU/mL) following entecavir therapy. Conclusions: HCV reactivation did occur during HBV suppression, and the rate was 4.5% (3/66), 15.4% (2/13), and 1.9% (1/53), for all patients, CHC patients, and patients with resolved past HCV infection, respectively. The reverse HBV and HCV viral evolutions at 6mEOT indicate that HBV relapse may suppress HCV replication again.

GSK2818713, a Novel Biphenylene Scaffold-Based Hepatitis C NS5A Replication Complex Inhibitor with Broad Genotype Coverage.

Pan-genotype NS5A inhibitors underpin hugely successful hepatitis C virus (HCV) therapy. The discovery of GSK2818713 (13), a nonstructural protein 5A (NS5A) HCV inhibitor characterized by a significantly improved genotype coverage relative to first-generation NS5A inhibitor daclatasvir (DCV), is detailed herein. The SAR analysis revealed cooperative potency effects of the biphenylene, bicyclic pyrrolidine (Aoc), and methyl-threonine structural motifs. Relative to DCV, 13 improved activity against genotype 1a (gt1a) and gt1b NS5A variants as well as HCV chimeric replicons containing NS5A fragments from genotypes 2-6. Long-term treatment of subgenomic replicons with 13 potently and durably decreased HCV RNA levels for gt1a, gt2a, and gt3a. These properties, suitable pharmacokinetics, and the lack of cross-resistance resulted in the selection of 13 as a preclinical candidate.

SPSB2 inhibits hepatitis C virus replication by targeting NS5A for ubiquitination and degradation.

Hepatitis C virus (HCV) replication involves many viral and host factors. Host factor SPRY domain- and SOCS box-containing protein 2(SPSB2) belongs to SPSB family, and it recruits target proteins by the SPRY domain and forms E3 ubiquitin ligase complexes by the SOCS box. As an adaptor protein, it can regulate the host’s response to infection, but little is known about whether SPSB2 plays a role in HCV replication. In the present study, we found that HCV infection significantly upregulated the mRNA and protein levels of SPSB2 in HCVcc-infected cells. Exogenous expression of SPSB2 in hepatoma cells decreased HCV RNA and protein levels which depended on the SOCS box, while knockdown of endogenous SPSB2 increased HCV RNA and protein levels. Additionally, we demonstrated that SPSB2 interacted with HCV structural protein E1 and nonstructural protein protein 5A (NS5A) via the C-terminal portion of the SPSB2 SPRY domain. Furthermore, SPSB2 induced NS5A ubiquitination and mediated NS5A degradation. Collectively, this study discovered host factor SPSB2 significantly inhibits HCV replication by interacting and degrading NS5A.

Viral dynamics among HCV infected patients with different genotypes treated with genotypic specific or pan-genotypic direct-acting antiviral agent combinations.

BackgroundNew hepatitis C virus (HCV) therapies have improved efficacy, allowed pangenotypic applications, increased barriers to drug resistance and shortened therapy duration.MethodsPatients infected with different HCV genotypes were divided into two groups: group 1 included 169 patients receiving genotypic specific regimens (GSR), while group 2 included 186 patients receiving pan-genotypic regimens (PGR). Patient’s HCV RNA was quantified and sequenced.ResultsComparable sustained viral response (SVR) rates were observed in both GSR and PGR treated patients. Nevertheless, even if not significant, a greater proportion of non-detectable levels (NDL) of HCV RNA was observed in patients treated with PGR as compared with GSR. Overall, among patients in the GSR and PGR groups with residual viremia, 124/169 (73.4%) and 125/186 (67.2%) at four weeks, and 66/169 (39.1%) and 58/186 (31.2%) at eight weeks, achieved SVR. No difference was observed in the clinical outcome comparing patients in the GSR and PGR groups according to genotype. While, comparing patients between the two groups, the proportion of patients with NDL HCV RNA at four and eight weeks was higher in patients infected with genotype 1b treated with PGR (p=0.0015). A significantly higher number of patients infected with 1b had RASs at baseline (p=0.0001). In addition, the proportion of patients with treatment failure was higher in patients with RASs at baseline compared with those without (p=0.012). Overall, 2.5% patients failed to achieve SVR after DAA treatment.ConclusionA sharp HCV RNA decrease was observed in patients treated with both GSR and PGR. However, even if comparable, a slightly greater number of patients treated with PGR achieved NDL HCV RNA as compared with GSR. A significant difference was observed in patients with baseline RASs, both in relation to treatment failure and genotype. In conclusion, the use of new DAA combinations helps patients achieve a more rapid virologic response.

Abl Tyrosine Kinase Regulates Hepatitis C Virus Entry.

Abl is a central regulator of multiple cellular processes controlling actin dynamics, proliferation, and differentiation. Here, we showed that knockdown of Abl impaired hepatitis C virus (HCV) propagation. Treatment of Abl tyrosine kinase-specific inhibitor, imatinib and dasatinib, also significantly decreased HCV RNA and protein levels in HCV-infected cells. We showed that both imatinib and dasatinib selectively inhibited HCV infection at the entry step of HCV life cycle, suggesting that Abl kinase activity may be necessary for HCV entry. Using HCV pseudoparticle infection assays, we verified that Abl is required for viral entry. By employing transferrin uptake and immunofluorescence assays, we further demonstrated that Abl was involved in HCV entry at a clathrin-mediated endocytosis step. These data suggest that Abl may represent a novel host factor for HCV entry.

Diminished viral replication and compartmentalization of hepatitis C virus in hepatocellular carcinoma tissue

Analysis of hepatitis C virus (HCV) replication and quasispecies distribution within the tumor of patients with HCV-associated hepatocellular carcinoma (HCC) can provide insight into the role of HCV in hepatocarcinogenesis and, conversely, the effect of HCC on the HCV lifecycle. In a comprehensive study of serum and multiple liver specimens from patients with HCC who underwent liver transplantation, we found a sharp and significant decrease in HCV RNA in the tumor compared with surrounding nontumorous tissues, but found no differences in multiple areas of control non-HCC cirrhotic livers. Diminished HCV replication was not associated with changes in miR-122 expression. HCV genetic diversity was significantly higher in livers containing HCC compared with control non-HCC cirrhotic livers. Tracking of individual variants demonstrated changes in the viral population between tumorous and nontumorous areas, the extent of which correlated with the decline in HCV RNA, suggesting HCV compartmentalization within the tumor. In contrast, compartmentalization was not observed between nontumorous areas and serum, or in controls between different areas of the cirrhotic liver or between liver and serum. Our findings indicate that HCV replication within the tumor is restricted and compartmentalized, suggesting segregation of specific viral variants in malignant hepatocytes.

New use of an old drug: chloroquine reduces viral and ALT levels in HCV non-responders (a randomized, triple-blind, placebo-controlled pilot trial).

Hepatitis C virus (HCV) infection induces autophagy, but the virus assimilates the autophagic response into its own life cycle. Chloroquine (CQ) is an autophagy inhibitor that is clinically used to treat malaria. The aims of this pilot clinical trial were to evaluate the therapeutic potential and short-term safety of CQ in patients with chronic HCV genotype 1, who were unresponsive to a combination of pegylated interferon alpha and ribavirin. Ten non-responders to previous antiviral treatment(s) were randomized to receive either CQ (150 mg daily for 8 weeks) or placebo, and were followed for 4 weeks after CQ therapy. HCV RNA load and plasma alanine transaminase (ALT) levels were measured at baseline, week 4 (initial response), week 8 (end-of-treatment response), and at the end of 12 weeks. A significant decrease in HCV RNA after the treatments (week 8) was observed in all patients in the CQ group (P = 0.04). However, HCV RNA levels increased within 4 weeks after discontinuation of CQ treatment although they were still lower than baseline. In addition, the ALT normalized during treatment in the CQ group. However, this response was also lost after treatment cessation. This study provides preliminary evidence that CQ is possibly a safe treatment option for HCV non-responders.

Characteristics and Outcomes of HCV Genotype-1-Infected Patients Treated with Peginterferon and Ribavirin Combination Therapy with Discordant HCV Responses 4 and 12 Weeks after Starting Therapy

Objective: Some patients with chronic hepatitis C virus (HCV) infection fail to achieve complete early virologic response (EVR) despite a marked decrease in HCV RNA at 4 weeks. We investigated the characteristics and final treatment outcomes of this patient subpopulation. Methods: A total of 516 patients with HCV genotype 1 were enrolled. Background characteristics and final outcomes were compared between patients who achieved complete EVR and those who did not among patients whose HCV RNA levels decreased 3.0 log₁₀ or more at 4 weeks. Results: 78 of 334 patients (23.4%) with a ≥3.0 log₁₀ reduction in HCV RNA levels at 4 weeks failed to achieve complete EVR. Female sex, higher pretreatment HCV RNA levels and lower baseline alanine aminotransferase (ALT) activity were independently associated with failure of complete EVR. The rate of sustained virologic response (SVR) in patients without complete EVR was 47.4%, significantly lower than that in patients with complete EVR (89.7%, p < 0.0001). Conclusions: Female patients, patients with higher pretreatment HCV RNA levels and patients with lower baseline ALT have a high likelihood of failure of complete EVR even when they had a ≥3 log₁₀ reduction of HCV RNA at 4 weeks, resulting in a significantly lower SVR rate.

Sustained virological response based on the week 4 response in hepatitis C virus genotype 1 patients treated with peginterferons α-2a and α-2b, plus ribavirin

It is unclear whether the magnitude of reduction in hepatitis C virus (HCV) RNA between baseline and week 4 of peginterferon-ribavirin treatment influences the probability of achieving a sustained virological response (SVR) in patients without a rapid virological response (RVR). Data of 151 genotype 1 chronic hepatitis C patients treated with 48 weeks of peginterferon α-2a (group 1, n=86) and peginterferon α-2b (group 2, n=65), plus ribavirin, were evaluated retrospectively. Patients of each group were further divided into those who had RVR and those who did not. Patients without an RVR were then subdivided into four discrete categories on the basis of the magnitude of decrease in HCV RNA from baseline to week 4: those with a ≥3 log10 drop, those with a ≥2 log10 but <3 log10 drop, those with a ≥1 log10 but <2 log10 drop, and those with a <1 log10 drop. The proportion of SVR was calculated for each category. Overall, 80 and 88.2% of RVR patients and 41.2 and 39.6% of non-RVR patients achieved an SVR in group 1 and group 2, respectively. Among non-RVR patients, the SVR rates were 75, 50, 16.7, and 11.1% in group 1 (trend test P=0.001) and 63.6, 42.9, 30, and 23.1% in group 2 (trend test P=0.038) in those with a drop in HCV RNA level of ≥3 log10, ≥2 log10, ≥1 log10, and <1 log10 at week 4, respectively. Patients with a ≥3 log10 drop in HCV RNA at week 4 have a high probability of achieving an SVR when treated with either peginterferon α-2a-ribavirin or peginterferon α-2b-ribavirin.

A Human Proteome Microarray Identifies that the Heterogeneous Nuclear Ribonucleoprotein K (hnRNP K) Recognizes the 5′ Terminal Sequence of the Hepatitis C Virus RNA

Stem-loop I (SL1) located in the 5' untranslated region of the hepatitis C virus (HCV) genome initiates binding to miR-122, a microRNA required for hepatitis HCV replication. However, proteins that bind SL1 remain elusive. In this study, we employed a human proteome microarray, comprised of ∼17,000 individually purified human proteins in full-length, and identified 313 proteins that recognize HCV SL1. Eighty-three of the identified proteins were annotated as liver-expressing proteins, and twelve of which were known to be associated with hepatitis virus. siRNA-induced silencing of eight out of 12 candidate genes led to at least 25% decrease in HCV replication efficiency. In particular, knockdown of heterogeneous nuclear ribonucleoprotein K (hnRNP K) reduced HCV replication in a concentration-dependent manner. Ultra-violet-crosslinking assay also showed that hnRNP K, which functions in pre-mRNA processing and transport, showed the strongest binding to the HCV SL1. We observed that hnRNP K, a nuclear protein, is relocated in the cytoplasm in HCV-expressing cells. Immunoprecipitation of the hnRNP K from Huh7.5 cells stably expressing HCV replicon resulted in the co-immunoprecipitation of SL1. This work identifies a cellular protein that could have an important role in the regulation of HCV RNA gene expression and metabolism.

Characterization of vaniprevir, a hepatitis C virus NS3/4A protease inhibitor, in patients with HCV genotype 1 infection: Safety, antiviral activity, resistance, and pharmacokinetics

Vaniprevir is a competitive inhibitor of the hepatitis C virus (HCV) NS3/4A protease that has potent anti-HCV activity in preclinical models. This placebo-controlled dose-ranging study assessed the safety, tolerability, and antiviral efficacy of vaniprevir monotherapy in patients with genotype 1 chronic HCV infection. Treatment-naive and treatment-experienced non-cirrhotic adult patients with baseline HCV RNA >106IU/ml were randomized to receive placebo or vaniprevir at doses of 125mg qd, 600mg qd, 25mg bid, 75mg bid, 250mg bid, 500mg bid, and 700mg bid for 8days. Forty patients (82.5% male, 75% genotype 1a) received at least one dose of placebo or vaniprevir. After 1week of vaniprevir, the decrease in HCV RNA from baseline ranged from 1.8 to 4.6log10IU/ml across all treatment groups, and there was a greater than dose-proportional increase in vaniprevir exposure at doses above 75mg bid. The most commonly reported drug-related adverse events (AEs) were diarrhea (n=5) and nausea (n=5). No pattern of laboratory or ECG abnormalities was observed, all AEs resolved during the study, and there were no discontinuations due to AEs. No serious AEs were reported. Resistance-associated amino acid variants were identified at positions R155 and D168 in patients infected with genotype 1a virus. Vaniprevir monotherapy demonstrated potent antiviral activity in patients with chronic genotype 1 HCV infection, and was generally well tolerated with no serious AEs or discontinuations due to AEs. Further development of vaniprevir, including studies in combination with other anti-HCV agents, is ongoing.

Lipid Droplet-Binding Protein TIP47 Regulates Hepatitis C Virus RNA Replication through Interaction with the Viral NS5A Protein

The nonstructural protein NS5A has emerged as a new drug target in antiviral therapies for Hepatitis C Virus (HCV) infection. NS5A is critically involved in viral RNA replication that takes place at newly formed membranes within the endoplasmic reticulum (membranous web) and assists viral assembly in the close vicinity of lipid droplets (LDs). To identify host proteins that interact with NS5A, we performed a yeast two-hybrid screen with the N-terminus of NS5A (amino acids 1–31), a well-studied α-helical domain important for the membrane tethering of NS5A. Our studies identified the LD-associated host protein, Tail-Interacting Protein 47 (TIP47) as a novel NS5A interaction partner. Coimmunoprecipitation experiments in Huh7 hepatoma cells confirmed the interaction of TIP47 with full-length NS5A. shRNA-mediated knockdown of TIP47 caused a more than 10-fold decrease in the propagation of full-length infectious HCV in Huh7.5 hepatoma cells. A similar reduction was observed when TIP47 was knocked down in cells harboring an autonomously replicating HCV RNA (subgenomic replicon), indicating that TIP47 is required for efficient HCV RNA replication. A single point mutation (W9A) in NS5A that disrupts the interaction with TIP47 but preserves proper subcellular localization severely decreased HCV RNA replication. In biochemical membrane flotation assays, TIP47 cofractionated with HCV NS3, NS5A, NS5B proteins, and viral RNA, and together with nonstructural viral proteins was uniquely distributed to lower-density LD-rich membrane fractions in cells actively replicating HCV RNA. Collectively, our data support a model where TIP47—via its interaction with NS5A—serves as a novel cofactor for HCV infection possibly by integrating LD membranes into the membranous web.

Antiviral activity of boceprevir monotherapy in treatment-naive subjects with chronic hepatitis C genotype 2/3

To examine the antiviral activity of boceprevir, a hepatitis C virus (HCV) protease inhibitor, in HCV genotype (G) 2/3-infected patients. We assessed boceprevir and telaprevir activity against an HCV G2 and G3 isolates enzyme panel, in replicon, and in phenotypic cell-based assays. Additionally, a phase I study evaluated the antiviral activity of boceprevir monotherapy (200mg BID, 400mg BID, or 400mg TID) vs. placebo for 14 days in HCV G2/3 treatment-naive patients. Boceprevir and telaprevir similarly inhibited G1 and G2 NS3/4A enzymes and replication in G1 and G2 replicon and cell-based assays. However, telaprevir demonstrated lower potency than boceprevir against HCV G3a enzyme (Ki=75 nM vs. 17 nM), in the G3a replicon assay (EC₅₀=953 nM vs. 159 nM), and against HCV G3a NS3 isolates (IC₅₀=3312 nM vs. 803 nM) in the cell-based assay. In HCV G2/3-infected patients, boceprevir (400 mg TID) resulted in a maximum mean decrease in HCV RNA of -1.60 log vs. -0.21 log with placebo. In vitro, boceprevir is more active than telaprevir against the HCV G3 NS3/4A enzyme in cell-based and biochemical assays and against G3 isolates in replicon assays. In HCV G2/3-infected treatment-naive patients, decreases in HCV RNA levels with boceprevir (400 mg TID) were comparable to those observed with the same dose in HCV treatment-experienced G1-infected patients.

Hepatitis C virus kinetics after liver transplantation to study the role of a small molecule inhibitor of viral entry

BackgroundAfter liver transplantation in patients infected with hepatitis C virus (HCV), reinfection of the transplanted liver is universal. The targeting of viral entry at the time of transplantation is therefore an attractive strategy. An understanding of the mechanisms and kinetics of this process will allow rational studies of small molecule inhibitors or neutralising antibodies that target HCV entry. MethodsAs part of a proof of concept study of ITX5061 (a small molecule antagonist of the HCV entry receptor, scavenger receptor B-I), we have studied detailed HCV kinetics. HCV RNA was quantified in plasma before and after liver transplantation. This study is registered with ClinicalTrials.gov, number NCT01292824. Findings13 patients were studied (median age 57 years, 11 male). Seven patients were infected with genotype 1, four with genotype 3, and one each with genotypes 2 and 4. During the period when no blood flowed through the liver there was a slow decline in plasma HCV RNA. After implantation of the donor liver there was a rapid decrease in HCV RNA in the plasma indicating entry of viral particles into the liver. Typically, there was a 90–99% decrease in HCV RNA at 4 h after implantation. This decrease continued until 12 h after implantation in all patients, and the initial rapidity of HCV RNA decline suggests the presence of specialised clearance systems in the liver. After this decrease, five patients showed a steady increase in plasma HCV RNA, which returned to baseline within 96 h indicating a rapid establishment of productive infection in the allograft. In the remaining eight patients there was a prolonged nadir for up to 21 days after transplant suggesting innate immune control in the transplanted liver. No differences in kinetics were observed between patients infected with different viral genotypes, or in the degree of liver injury at the time of transplantation. InterpretationThese marked differences in viral kinetics have major implications for trial design and probably have important biological significance in innate control of infection. FundingNational Institute for Health Research.

Boceprevir dosing for late responders and null responders: The role of bridging data between treatment-naïve and -experienced subjects

Boceprevir dosing for late responders and null responders: The role of bridging data between treatment-naïve and -experienced subjects

Ethanol facilitates hepatitis C virus replication via up-regulation of GW182 and heat shock protein 90 in human hepatoma cells

Alcohol use and hepatitis C virus (HCV) infection synergize to cause liver damage, and microRNA-122 (miR-122) appears to play a key role in this process. Argonaute 2 (Ago2), a key component of the RNA-induced silencing complex (RISC), has been shown to be important in modulating miR-122 function during HCV infection. However, GW182, a critical component of processing bodies (GW bodies) that is recruited by Ago2 to target messenger RNA (mRNA), has not been assessed in HCV infection. To characterize the role of GW182 in the pathogenesis of HCV infection, we determined its transcription and protein expression in an HCV J6/JFH1 culture system. Transcript and protein levels of GW182 as well as HCV RNA and protein expression increased with alcohol exposure. Specific silencing of mRNA expression by small interfering RNA against GW182 significantly decreased HCV RNA and protein expression. Overexpression of GW182 significantly increased HCV RNA and protein expression in HCV J6/JFH1 infected Huh7.5 cells. Furthermore, GW182 colocalized and coimmunoprecipitated with heat shock protein 90 (HSP90), which increased upon alcohol exposure with and without HCV infection and enhanced HCV gene expression. The use of an HSP90 inhibitor or knockdown of HSP90 decreased GW182 and miR-122 expression and significantly reduced HCV replication. Overall, our results suggest that GW182 protein that is linked to miR-122 biogenesis and HSP90, which has been shown to stabilize the RISC, are novel host proteins that regulate HCV infection during alcohol abuse.

Pharmacokinetics, Pharmacodynamics, and Tolerability of GS-9851, a Nucleotide Analog Polymerase Inhibitor, following Multiple Ascending Doses in Patients with Chronic Hepatitis C Infection

We conducted this double-blind, parallel-group, placebo-controlled, randomized, multiple-ascending-dose study to assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of GS-9851 (formerly PSI-7851) in treatment-naïve patients infected with hepatitis C virus (HCV) genotype 1. Thirty-two patients received active doses up to 400 mg of GS-9851 once daily for 3 days. GS-9851 and the metabolite GS-566500 (formerly PSI-352707) were rapidly cleared from the plasma, with half-life (t(1/2)) values of approximately 1 h for GS-9851 and 3 h for GS-566500. Accumulation (21%) was observed only for GS-331007 (formerly PSI-6206) after multiple dosing. GS-331007 was the primary drug-related moiety in the plasma and urine. Increases in the GS-9851, GS-566500, and GS-331007 maximum concentrations in plasma (C(max)) and area under the concentration-time curve (AUC) were less than dose proportional, particularly at the highest doses. The decline in plasma HCV RNA levels was dose dependent, and a mean maximal change from the baseline of -1.95 log(10) IU/ml was obtained for 400 mg GS-9851, compared with -0.090 log(10) IU/ml for the placebo. Most patients had a decrease in HCV RNA of ≥1.0 log(10) IU/ml after 3 days' dosing with 400 mg GS-9851. No virologic resistance was observed. GS-9851 was generally well tolerated, with no notable differences in adverse event frequency across doses. The pharmacokinetic profile observed in this study was similar to that seen in a single-ascending-dose study in healthy subjects.

Interference with ERK and STAT signaling pathways and inhibition of hepatitis C virus replication by ribavirin

Ribavirin in combination with interferon (IFN)-α is the approved treatment for hepatitis C virus (HCV) infection. Interference of ribavirin with signaling events is involved in its biological activities. However, little is known of signaling pathways induced by ribavirin following HCV infection. In human hepatoma cells, effects of ribavirin on ERK and signal transducers and activators of transcription (STAT) pathways, HCV replication, and antiviral gene expression were evaluated before and after cell culture-derived HCV infection. Ribavirin reduced phosphorylation of Raf, MEK, ERK, Tyk2, and STAT1, but selectively increased STAT3 phosphorylation. IFN-α synergistically regulated ERK and STAT3 phosphorylation with ribavirin, and up-regulated expression and phosphorylation of STAT1. Ribavirin dose-dependently decreased HCV RNA replication and HCV protein expression, with slight induction of IFN regulatory factor 9 and IFN-stimulated gene 15. Ribavirin and IFN-α exerted a synergetic inhibitory effect on HCV. ERK and STAT pathways were down-regulated by ribavirin following HCV infection. These results suggest that ribavirin may mediate anti-HCV activity through interference with ERK and STAT pathways.

Factors That Predict Response of Patients With Hepatitis C Virus Infection to Boceprevir

Little is known about factors associated with a sustained virologic response (SVR) among patients with hepatitis C virus (HCV) infection to treatment with protease inhibitors. Previously untreated patients (from the Serine Protease Inhibitor Therapy 2 [SPRINT-2] trial) and those who did not respond to prior therapy (from the Retreatment with HCV Serine Protease Inhibitor Boceprevir and PegIntron/Rebetol 2 [RESPOND-2] trial) received either a combination of peginterferon and ribavirin for 48 weeks or boceprevir, peginterferon, and ribavirin (triple therapy) after 4 weeks of peginterferon and ribavirin (total treatment duration, 28-48 wk). A good response to interferon was defined as a ≥ 1 log(10) decrease in HCV RNA at week 4; a poor response was defined as a <1 log(10) decrease. We used multivariate regression analyses to identify baseline factors of the host (including the polymorphism interleukin [IL]-28B rs12979860) associated with response. The polymorphism IL-28B rs8099917 also was assessed. In the SPRINT-2 trial, factors that predicted a SVR to triple therapy included low viral load (odds ratio [OR], 11.6), IL-28B genotype (rs 12979860 CC vs TT and CT; ORs, 2.6 and 2.1, respectively), absence of cirrhosis (OR, 4.3), HCV subtype 1b (OR, 2.0), and non-black race (OR, 2.0). In the RESPOND-2 trial, the only factor significantly associated with a SVR was previous relapse, compared with previous nonresponse (OR, 2.6). Most patients with rs12979860 CC who received triple therapy had undetectable levels of HCV RNA by week 8 (76%-89%), and were eligible for shortened therapy. In both studies, IL-28B rs12979860 CC was associated more strongly with a good response to interferon than other baseline factors; however, a ≥ 1 log(10) decrease in HCV-RNA level at week 4 was associated more strongly with SVR than IL-28B rs12979860. Combining the rs8099917 and rs12979860 genotypes does not increase the association with SVR. The CC polymorphism at IL-28B rs12979860 is associated with response to triple therapy and can identify candidates for shorter treatment durations. A ≥ 1 log(10) decrease in HCV RNA at week 4 of therapy is the strongest predictor of a SVR, regardless of polymorphisms in IL-28B.

Up-regulation of Hedgehog pathway is associated with cellular permissiveness for hepatitis C virus replication

Studies of the hepatitis C virus (HCV) life-cycle rely heavily on Huh7.5 cells, but the reasons why these cells are exceptionally permissive for HCV replication are not clear. Based on recent clinical observations, we hypothesized that the Hedgehog (Hh) pathway, which has not been previously associated with HCV replication, may be involved in the Huh7.5 phenotype of increased permissiveness. We tested this hypothesis by comparing levels of a variety of Hh-related cellular markers in Huh7.5 cells with the parental Huh7 cells, which are far less permissive. Here we demonstrate that Huh7.5 cells, when compared with Huh7 cells, have substantially decreased expression of epithelial markers, increased levels of mesenchymal markers, and markedly up-regulated Hh pathway activity: Shh, >100-fold, Gli1, >30-fold, Ptc, 2-fold. In Huh7.5 cells, we found that cyclopamine, an Hh pathway antagonist, reduced HCV RNA levels by 50% compared with vehicle and inactive isomer controls. Moreover, in Huh7 cells treatment with recombinant Shh ligand and SAG, both Hh pathway agonists, stimulated HCV replication by 2-fold and 4-fold, respectively. These effects were observed with both viral infections and a subgenomic replicon. Finally, we demonstrated that GDC-0449 decreased HCV RNA levels in a dose-response manner. We have identified a relationship between HCV and Hh signaling where up-regulated pathway activity during infection promotes an environment conducive to replication. Given that Hh activity is very low in most hepatocytes, these findings may serve to further shift the model of HCV liver infection from modest widespread replication in hepatocytes to one where a subset of cells support high-level replication. These findings also introduce Hh pathway inhibitors as potential anti-HCV therapeutics.