Placebo-controlled trial of 400 mg amantadine combined with peginterferon alfa-2a and ribavirin for 48 weeks in chronic hepatitis C virus-1 infection

Patch-Clamp Study of Hepatitis C p7 Channels Reveals Genotype-Specific Sensitivity to Inhibitors

Hepatitis C is a major worldwide disease and health hazard, affecting ∼3% of the world population. The p7 protein of hepatitis C virus (HCV) is an intracellular ion channel and pH regulator that is involved in the viral replication cycle. It is targeted by various classical ion channel blockers. Here, we generated p7 constructs corresponding to HCV genotypes 1a, 2a, 3a, and 4a for recombinant expression in HEK293 cells, and studied p7 channels using patch-clamp recording techniques. The pH50 values for recombinant p7 channels were between 6.0 and 6.5, as expected for proton-activated channels, and current-voltage dependence did not show any differences between genotypes. Inhibition of p7-mediated currents by amantadine, however, exhibited significant, genotype-specific variation. The IC50 values of p7-1a and p7-4a were 0.7 ± 0.1 nM and 3.2 ± 1.2 nM, whereas p7-2a and p7-3a had 50- to 1000-fold lower sensitivity, with IC50 values of 2402 ± 334 nM and 344 ± 64 nM, respectively. The IC50 values for rimantadine were low across all genotypes, ranging from 0.7 ± 0.1 nM, 1.6 ± 0.6 nM, and 3.0 ± 0.8 nM for p7-1a, p7-3a, and p7-4a, respectively, to 24 ± 4 nM for p7-2a. Results from patch-clamp recordings agreed well with cellular assays of p7 activity, namely, measurements of intracellular pH and hemadsorption assays, which confirmed the much reduced amantadine sensitivity of genotypes 2a and 3a. Thus, our results establish patch-clamp studies of recombinant viroporins as a valid analytical tool that can provide quantitative information about viroporin channel properties, complementing established techniques.

[From the national competence network for viral hepatitis (HepNet) emerged the German Liver Foundation (Deutsche Leberstiftung)]

The competence network for viral hepatitis (HepNet) was founded in 2002 with funding from the German government and has influenced the research on viral hepatitis in Germany. HepNet collaborator sites have been involved in numerous national and international investigator-initiated, as well as industry-sponsored, phase 1-3 studies. Within the HepNet Study-House, many groundbreaking investor-initiated trials have been completed and are still ongoing. For example, the acute hepatitis C trials and trials on chronic hepatitis D (delta), which led to therapy optimization. Continuation of the competence network on viral hepatitis has been achieved by the foundation of the German Liver Foundation, which has been an external cooperation partner of the German Center for Infection Research (DZIF) for two years. The well-established HepNet Study-House acts here as the clinical trial platform for all DZIF hepatitis trials.

Computational Docking Study of p7 Ion Channel from HCV Genotype 3 and Genotype 4 and Its Interaction with Natural Compounds

Background

The current standard care therapy for hepatitis C virus (HCV) infection consists of two regimes, namely interferon-based and interferon-free treatments. The treatment through the combination of ribavirin and pegylated interferon is expensive, only mildly effective, and is associated with severe side effects. In 2011, two direct-acting antiviral (DAA) drugs, boceprevir and telaprevir, were licensed that have shown enhanced sustained virologic response (SVR) in phase III clinical trial, however, these interferon-free treatments are more sensitive to HCV genotype 1 infection. The variable nature of HCV, and the limited number of inhibitors developed thus aim in expanding the repertoire of available drug targets, resulting in targeting the virus assembly therapeutically.

Aim

We conducted this study to predict the 3D structure of the p7 protein from the HCV genotypes 3 and 4. Approximately 63 amino acid residues encoded in HCV render this channel sensitive to inhibitors, making p7 a promising target for novel therapies. HCV p7 protein forms a small membrane known as viroporin, and is essential for effective self-assembly of large channels that conduct cation assembly and discharge infectious virion particles.

Method

In this study, we screened drugs and flavonoids known to disrupt translation and production of HCV proteins, targeted against the active site of p7 residues of HCV genotype 3 (GT3) (isolatek3a) and HCV genotype 4a (GT4) (isolateED43). Furthermore, we conducted a quantitative structure–activity relationship and docking interaction study.

Results

The drug NB-DNJ formed the highest number of hydrogen bond interactions with both modeled p7 proteins with high interaction energy, followed by BIT225. A flavonoid screen demonstrated that Epigallocatechin gallate (EGCG), nobiletin, and quercetin, have more binding modes in GT3 than in GT4. Thus, the predicted p7 protein molecule of HCV from GT3 and GT4 provides a general avenue to target structure-based antiviral compounds.

Conclusions

We hypothesize that the inhibitors of viral p7 identified in this screen may be a new class of potent agents, but further confirmation in vitro and in vivo is essential. This structure-guided drug design for both GT3 and GT4 can lead to the identification of drug-like natural compounds, confirming p7 as a new target in the rapidly increasing era of HCV.

Aminoadamantanes for chronic hepatitis C

BACKGROUND

Around 3% of the world's population (approximately 160 million people) are chronically infected with hepatitis C virus. The proportion of infected people who develop clinical symptoms varies between 5% and 40%. Combination therapy with pegylated interferon-alpha plus ribavirin eradicates the virus from the blood six months after treatment (sustained virological response) in approximately 40% to 80% of infected patients, depending on the viral genotype. New antiviral agents, such as boceprevir and telaprevir, in combination with standard therapy, can increase sustained virological response in genotype 1 infected patients to at least 70%. There is therefore an unmet need for drugs that can achieve a higher proportion of sustained virological response. Aminoadamantanes are antiviral drugs used for treatment of patients with chronic hepatitis C.

OBJECTIVES

To assess the beneficial and harmful effects of aminoadamantanes for patients with chronic hepatitis C infection by conducting a systematic review with meta-analyses of randomised clinical trials, as well as trial sequential analyses.

SEARCH METHODS

We conducted electronic searches of the Cochrane Hepato-Biliary Group Controlled Trials Register (1996 to December 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 11 of 12 (1995 to December 2013), MEDLINE (1946 to December 2013), EMBASE (1974 to December 2013), Science Citation Index EXPANDED (1900 to December 2013), the WHO International Clinical Trials Registry Platform (www.who.int/ictrp), Google Scholar, and Eudrapharm up to December 2013 and checked the reference lists of identified publications.

SELECTION CRITERIA

Randomised clinical trials assessing aminoadamantanes in patients with chronic hepatitis C infection.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. We assessed for risks of systematic errors ('bias') using the 'Risk of bias' tool. We analysed dichotomous data with risk ratio (RR) and continuous data with mean difference (MD) or standardised mean difference (SMD), both with 95% confidence intervals (CI). We used trial sequential analysis to assess the risk of random errors ('play of chance'). We assessed quality using the GRADE system.

MAIN RESULTS

We included 41 randomised clinical trials with 6193 patients with chronic hepatitis C. All trials had high risk of bias. All included trials compared amantadine versus placebo or no intervention. Standard antiviral therapy was administered equally to the intervention and the control groups in 40 trials. The standard antiviral therapy, which was administered to both intervention groups, was interferon-alpha, interferon-alpha plus ribavirin, and peg interferon-alpha plus ribavirin, depending on the time when the trial was conducted.When we meta-analysed all trials together, the overall results demonstrated no significant effects of amantadine, when compared with placebo or no intervention, on our all-cause mortality or liver-related morbidity composite outcome (5/2353 (0.2%) versus 6/2264 (0.3%); RR 0.90, 95% CI 0.38 to 2.17; I² = 0%; 32 trials; very low quality). There was also no significant effect on adverse events (288/2869 (10%) versus 293/2777 (11%); RR 0.98, 95% CI 0.84 to 1.14; I² = 0%; 35 trials; moderate quality). We used both fixed-effect and random-effects meta-analyses. Amantadine, when compared with placebo or no intervention, did not significantly influence the number of patients who failed to achieve a sustained virological response (1821/2861 (64%) versus 1737/2721 (64%); RR 0.98, 95% CI 0.95 to 1.02; I² = 35%; 35 trials; moderate quality). However, in the subgroup using interferon plus ribavirin, amantadine decreased the number of patients who failed to achieve a sustained virological response (422/666 (63%) versus 447/628 (71%); RR 0.89, 95% CI 0.83 to 0.96; I² = 41%; 11 trials; low quality). Similar results were found for failure to achieve an end of treatment virological response. Amantadine, when compared with placebo or no intervention, significantly decreased the number of patients without normalisation of alanine aminotransferase (ALT) serum levels at the end of treatment (671/1141 (59%) versus 732/1100 (67%); RR 0.88, 95% CI 0.83 to 0.94; I² = 47%; 19 trials; low quality). Amantadine, when compared with placebo or no intervention, did not significantly influence the end of follow-up biochemical response (1133/1896 (60%) versus 1151/1848 (62%); RR 0.95, 95% CI 0.91 to 1.00; I² = 49%; 21 trials; low quality).The observed beneficial effects could be true effects but could also be due to both systematic errors (bias) and random errors (play of chance). The latter is due to the fact that trial sequential analyses could not confirm or refute our findings. We were not able to perform meta-analyses for failure of histological improvement or quality of life due to a lack of valid data.

AUTHORS' CONCLUSIONS

This systematic review does not demonstrate any significant effects of amantadine on all-cause mortality or liver-related morbidity composite outcome and on adverse events in patients with hepatitis C; however, the median trial duration was 12 months, with a median follow-up of six months, which is not long enough to assess the composite outcome sufficiently. Overall, we did not see an effect of amantadine on failure to achieve a sustained virological response. Subgroup analyses demonstrated that the combination of amantadine plus interferon-alpha and ribavirin seems to increase the number of patients achieving a sustained virological response. This finding may be caused by both systematic errors (bias) and risks of random errors (play of chance), but it could also be real. Based on the results of the overall evidence, it appears less likely that future trials assessing amantadine for patients with chronic hepatitis C will show strong benefits. Therefore, it is probably advisable to wait for the results of trials assessing other direct-acting antiviral drugs. In the absence of convincing evidence of benefit, the use of amantadine is justified in the context of randomised clinical trials assessing the effects of combination therapy. We found a lack of evidence on other aminoadamantanes than amantadine.

SVR12 is higher than SVR24 in treatment-naïve hepatitis C genotype 1 patients treated with peginterferon plus ribavirin

BACKGROUND

Randomized clinical trials (RCTs) of interventions for the hepatitis C virus have historically used sustained virological response (SVR) at 24 weeks after treatment (SVR24) as the key effect measure. However, recent RCTs investigating the efficacy of new direct acting agents (DAAs) have used SVR at 12 weeks after treatment (SVR12). While there is evidence to suggest SVR24 and SVR12 are similar in patients receiving new DAAs, this is unlikely to be true for patients receiving backbone peginterferon-ribavirin control treatment. Establishing the difference between SVR12 and SVR24 for patients receiving peginterferon-ribavirin treatment is therefore necessary to avoid biased interpretations of the benefits of newer DAAs.

METHODS

We searched the MEDLINE®, Embase™, and Cochrane CENTRAL for RCTs with a peginterferon-ribavirin arm that used SVR24 and/or SVR12. As no RCTs reported on both, we pooled SVR12 and SVR24 proportions using conventional meta-analysis. Proportions were pooled separately for peginterferon alpha-2a and alpha-2b. Further, a Bayesian meta-regression model was employed to estimate the difference between SVR12 and SVR24.

RESULTS

Thirty-five RCTs including a peginterferon arm were identified. Twenty-four trials included a peginterferon alpha-2a plus ribavirin arms, of which 20 reported SVR24 and five reported SVR12. Seventeen trials included a peginterferon alpha-2b plus ribavirin arm, of which 16 reported SVR24 and one reported SVR12. Using Bayesian meta-regression, the pooled SVR12 was 6% higher than SVR24 with peginterferon alpha-2a (53% versus 47%) and 5% higher with peginterferon alpha-2b (45% versus 40%) and 95% credible intervals (CrIs) were only marginally overlapping. The meta-regression also demonstrated a marginally significant relative risk of 1.13 (95% CrI 0.99-1.26) of SVR12 versus SVR24. The conventional pairwise meta-analyses were consistent with these findings.

CONCLUSION

Considering the relatively large difference observed between SVR12 and SVR24, it seems reasonable to insist that future clinical trials report both to allow for complete transparency and clarity in their interpretation.

Low vitamin D serum concentration is associated with high levels of hepatitis B virus replication in chronically infected patients

Vitamin D is an important immune modulator that plays an emerging role in inflammatory and metabolic liver diseases, including infection with hepatitis C virus (HCV). In contrast, the relationship between vitamin D metabolism and chronic hepatitis B (CHB) is less well characterized. Therefore, we quantified 25(OH)D3 serum levels in a cohort of 203 treatment-naïve patients with chronic hepatitis B virus (HBV) infection and tested for their association with clinical parameters of CHB. Of 203 patients, 69 (34%), 95 (47%), and 39 (19%) had severe vitamin D deficiency (25(OH)D3 <10 ng/mL), vitamin D insufficiency (25(OH)D3 ≥10 and <20 ng/mL), or adequate vitamin D serum levels (25(OH)D3 ≥20 ng/mL), respectively. In both uni- and multivariate analyses, HBV DNA viral load (log10 IU/mL) was a strong predictor of low 25(OH)D3 serum levels (P = 0.0007 and P = 0.000048, respectively) and vice versa. Mean 25(OH)D3 serum concentrations in patients with HBV DNA <2,000 versus ≥2,000 IU/mL were 17 versus 11 ng/mL, respectively (P < 0.00001). In addition, hepatitis B early antigen (HBeAg)-positive patients had lower 25(OH)D3 serum levels than HBeAg-negative patients (P = 0.0013). Finally, 25(OH)D3 and HBV DNA serum levels showed inverse seasonal fluctuations.

CONCLUSION

Low 25(OH)D3 serum levels are associated with high levels of HBV replication in patients with CHB. This represents a major difference from chronic hepatitis C, where numerous previous studies have shown a lack of correlation between HCV viral load and vitamin D serum levels. Inverse seasonal fluctuations of 25(OH)D3 and HBV DNA serum levels are suggestive of a functional relationship between both variables.

Efficiency of E2-p7 processing modulates production of infectious hepatitis C virus

Previous studies indicate that the processing of hepatitis C virus (HCV) E2-p7-NS2 precursor mediated by host signal peptidase is relatively inefficient, resulting in the accumulation of E2-p7-NS2 and E2-p7 precursors in addition to E2 in mammalian cells. In this study, we discovered that a significant inhibition of the processing at an E2-p7 junction site is detrimental for HCV production, whether it was caused by the mutations in p7 or by the strategic introduction of a mutation at a terminal residue of E2 to block the signal peptidase-mediated cleavage of this junction site. However, complete separation of E2 and p7 by inserting an encephalomyocarditis virus (EMCV) internal ribosome entry site (IRES) between these two proteins also moderately inhibited virus production. These results indicate that optimal processing of the E2-p7 junction site is critical for efficient HCV production. We further demonstrated that disrupting E2-p7 processing inhibits both NS2 localization to the putative virus assembly sites near lipid droplets (LD) and NS2 interaction with NS3 and E2. However, the impact, if any, of the p7-NS2 processing efficiency on HCV production seems relatively minor. In conclusion, these results imply that effective release of E2 and p7 from the precursor E2-p7 promotes HCV production by enhancing NS2-associated virus assembly complex formation near LD.

Meta-analysis: mortality and serious adverse events of peginterferon plus ribavirin therapy for chronic hepatitis C

BACKGROUND

Pegylated interferon (PEG-IFN) plus ribavirin (RBV) therapy is the current standard of care for patients with chronic hepatitis C. Determining precisely the risk of serious adverse events (SAEs) and mortality from a single study is rather difficult because of the infrequency of such events. The aim of this systematic review was to assess the rates of SAEs and the mortality of PEG-IFN/RBV therapy in a pooled large sample, and to assess the relationship between SAEs and mortality rates and therapeutic characteristics.

METHODS

A literature search was conducted using MEDLINE, EMBASE, and the Cochrane Library to identify randomized controlled trials evaluating the efficacy and safety of PEG-IFN/RBV therapy. We calculated the crude mortality and SAE rates with 95% confidence intervals (CIs).

RESULTS

Eighty studies with 153 treatment arms that included 27569 patients were enrolled (14401 patients treated with Peg-IFN alpha-2a/RBV and 13168 with Peg-IFN alpha-2b/RBV). All-cause and treatment-related deaths were observed in 50 (0.18%; 95% confidence interval [CI] 0.13-0.24%) and sixteen (0.058%; 95% CI 0.033-0.094%) patients, respectively. The crude SAE rate was 7.08% (95% CI 6.75-7.41%). Subgroup analysis revealed higher SAE rates in patients receiving PEG-IFN alpha-2a than in those with PEG-IFN alpha-2b (7.45 vs. 6.74%), and higher SAE rates with higher doses than with the lower doses in PEG-IFN-2a and 2b (11.94 vs. 6.99%, 7.10 vs. 5.05%, respectively), and with extended duration (> 48 weeks) than with standard duration (48 weeks) (15.5 vs. 6.67%) in PEG-IFN alpha-2a.

CONCLUSION

The mortality rate during PEG-IFN/RBV therapy was acceptably low, but the rate of SAEs was not negligible in a treatment for a benign disease, and the rate was affected by treatment regimens.

Differences in clinical outcomes among hepatitis C genotype 1-infected patients treated with peginterferon alpha-2a or peginterferon alpha-2b plus ribavirin: a meta-analysis

Background

With the development of new direct acting antiviral (DAA) therapy for hepatitis C, the backbone peginterferon alpha used may be of importance in maximizing treatment outcomes. To this end, the rates of sustained virologic response (SVR), relapse, and treatment discontinuation among hepatitis C genotype 1-infected patients given peginterferon alpha-2a plus ribavirin or peginterferon alpha-2b plus ribavirin were determined using a meta-analysis.

Methods

Randomized trials examining peginterferon alpha-2a or peginterferon alpha-2b co-administered with ribavirin for 48 weeks were included. Data were extracted on SVR, relapse, and treatment discontinuations for treatment-naïve and treatment-experienced patients. Pooled proportions using fixed and random effects meta-analysis were calculated.

Results

Twenty-six trials provided data on patients treated with peginterferon alpha-2a plus ribavirin, and 19 trials provided data on patients treated with peginterferon alpha-2b plus ribavirin. Five trials were direct head-to-head evaluations. In the subset of trials that included head-to-head evaluations, no significant differences were observed between the two treatments for treatment-naïve (relative risk [RR]: 1.07, 95% confidence intervals [CI]: 0.97–1.18) and treatment-experienced patients (RR: 1.27, 95% CI: 0.58–2.77). Using only active trial arms, a larger proportion of the treatment- naïve patients who were provided peginterferon alpha-2a plus ribavirin achieved a SVR (47%), which is greater than that of treatment-naïve patients who were provided peginterferon alpha- 2b plus ribavirin (40% SVR achievement); however, a larger proportion of treatment- experienced patients who were provided peginterferon alpha-2b plus ribavirin achieved a SVR (16%) when compared with treatment-experienced patients given peginterferon alpha-2a plus ribavirin (12% SVR achievement). A larger proportion of relapses occurred among both treatment-naïve and treatment-experienced patients given peginterferon alpha-2a plus ribavirin, when compared with treatment-naïve and treatment-experienced patients taking peginterferon alpha-2b plus ribavirin. The proportion of patients discontinuing treatment was greater among treatment-naïve patients taking peginterferon alpha-2a plus ribavirin, but smaller among treatment-experienced patients.

Conclusion

There are small differences in treatment outcomes for different types of peginterferon- alpha. Patient status and complexity of administration may differentiate clinical outcomes.

The determination of GGT is the most reliable predictor of nonresponsiveness to interferon-alpha based therapy in HCV type-1 infection

BACKGROUND

The critical analysis of baseline factors has been found to be useful to predict virologic nonresponse (NR), relapse, or sustained virologic response (SVR) in patients infected with hepatitis C virus (HCV) who receive antiviral therapy. In the present retrospective study we tried to find out whether gamma-glutamyltranspeptidase (GGT) may be one of the baseline factors which are of special predictive power. We analyzed, in patients with different treatment outcomes, the predictive power of established baseline factors either in combination with GGT or by evaluating the predictive value of GGT independently.

METHODS

Individual data from 632 patients chronically infected with HCV type 1 (n = 561) or type 2/3 (n = 71) were analyzed. All patients had received their first course of antiviral therapy and were treated with pegylated interferon α-2a or -2b plus ribavirin.

RESULTS

In patients with HCV type 1, a multivariate multinomial logistic regression analysis identified low GGT (p < 0.0001), high cholesterol (p < 0.0001), age ≤ 40 years (p < 0.0001), high alanine aminotransferase (p = 0.0006), low viremia (p = 0.0014), and absence of cirrhosis (p = 0.0164) as independent predictors. While these baseline factors heralded improved virologic response, high GGT, in contrast, was significantly associated with NR (p < 0.0001). A strong correlation was found between log(10) GGT and a scoring variable S (r = -0.26 for prediction of SVR, p < 0.001; r = 0.11 for prediction of NR, p = 0.016) summarizing predictive information from other baseline factors.

CONCLUSIONS

These findings prove the predictive sensitivity of GGT as an independent indicator of nonresponsiveness even at levels that are slightly above the normal range. This new predictive parameter may help to improve individualized therapy in HCV type-1 infection.

Vitamin D deficiency and a CYP27B1-1260 promoter polymorphism are associated with chronic hepatitis C and poor response to interferon-alfa based therapy

BACKGROUND & AIMS

Vitamin D is an important immune modulator and preliminary data indicated an association between vitamin D deficiency and sustained virologic response (SVR) rates in hepatitis C virus (HCV) genotype 1 patients. We, therefore, performed a comprehensive analysis on the impact of vitamin D serum levels and of genetic polymorphisms with functional relevance within the vitamin D cascade on chronic hepatitis C and its treatment.

METHODS

Vitamin D serum levels, genetic polymorphisms within the vitamin D receptor and 1α-hydroxylase were determined in a cohort of 468 HCV genotype 1, 2, and 3 infected patients who were treated with interferon-alfa based regimens.

RESULTS

Chronic hepatitis C was associated with a high incidence of severe vitamin D deficiency compared to controls (25(OH)D(3)<10 ng/ml in 25% versus 12%, p<0.00001). 25(OH)D(3) deficiency correlated with SVR in HCV genotype 2 and 3 patients (50% and 81% SVR for patients with and without severe vitamin D deficiency, respectively, p<0.0001). In addition, the CYP27B1-1260 promoter polymorphism rs10877012 had substantial impact on 1,25-dihydroxyvitamin D serum levels (72, 61, and 60 pmol/ml for rs10877012 AA, AC, and CC, respectively, p=0.04) and on SVR rates in HCV genotype 1, 2, and 3 infected patients (77% and 65% versus 42% for rs10877012 AA, AC, and CC, respectively, p=0.02).

CONCLUSIONS

Chronic hepatitis C virus infection is associated with vitamin D deficiency. Reduced 25-hydroxyvitamin D levels and CYP27B1-1260 promoter polymorphism leading to reduced 1,25-dihydroxyvitamin D levels are associated with failure to achieve SVR in HCV genotype 1, 2, and 3 infected patients.

Emodin inhibits current through SARS-associated coronavirus 3a protein

The open-reading-frame 3a of SARS coronavirus (SARS-CoV) had been demonstrated previously to form a cation-selective channel that may become expressed in the infected cell and is then involved in virus release. Drugs that inhibit the ion channel formed by the 3a protein can be expected to inhibit virus release, and would be a source for the development of novel therapeutic agents. Here we demonstrate that emodin can inhibit the 3a ion channel of coronavirus SARS-CoV and HCoV-OC43 as well as virus release from HCoV-OC43 with a K1/2 value of about 20 μM. We suggest that viral ion channels, in general, may be a good target for the development of antiviral agents.

Coevolution of the hepatitis C virus polyprotein sites in patients on combined pegylated interferon and ribavirin therapy

Genotype-specific sensitivity of the hepatitis C virus (HCV) to interferon-ribavirin (IFN-RBV) combination therapy and reduced HCV response to IFN-RBV as infection progresses from acute to chronic infection suggest that HCV genetic factors and intrahost HCV evolution play important roles in therapy outcomes. HCV polyprotein sequences (n = 40) from 10 patients with unsustainable response (UR) (breakthrough and relapse) and 10 patients with no response (NR) following therapy were identified through the Virahep-C study. Bayesian networks (BNs) were constructed to relate interrelationships among HCV polymorphic sites to UR/NR outcomes. All models showed an extensive interdependence of HCV sites and strong connections (P ≤ 0.003) to therapy response. Although all HCV proteins contributed to the networks, the topological properties of sites differed among proteins. E2 and NS5A together contributed ∼40% of all sites and ∼62% of all links to the polyprotein BN. The NS5A BN and E2 BN predicted UR/NR outcomes with 85% and 97.5% accuracy, respectively, in 10-fold cross-validation experiments. The NS5A model constructed using physicochemical properties of only five sites was shown to predict the UR/NR outcomes with 83.3% accuracy for 6 UR and 12 NR cases of the HALT-C study. Thus, HCV adaptation to IFN-RBV is a complex trait encoded in the interrelationships among many sites along the entire HCV polyprotein. E2 and NS5A generate broad epistatic connectivity across the HCV polyprotein and essentially shape intrahost HCV evolution toward the IFN-RBV resistance. Both proteins can be used to accurately predict the outcomes of IFN-RBV therapy.

Dragon exploratory system on hepatitis C virus (DESHCV)

Even though hepatitis C virus (HCV) cDNA was characterized about 20 years ago, there is insufficient understanding of the molecular etiology underlying HCV infections. Current global rates of infection and its increasingly chronic character are causes of concern for health policy experts. Vast amount of data accumulated from biochemical, genomic, proteomic, and other biological analyses allows for novel insights into the HCV viral structure, life cycle and functions of its proteins. Biomedical text-mining is a useful approach for analyzing the increasing corpus of published scientific literature on HCV. We report here the first comprehensive HCV customized biomedical text-mining based online web resource, dragon exploratory system on hepatitis C virus (DESHCV), a biomedical text-mining and relationship exploring knowledge base was developed by exploring literature on HCV. The pre-compiled dictionaries existing in the dragon exploratory system (DES) were enriched with biomedical concepts pertaining to HCV proteins, their name variants and symbols to make it suitable for targeted information exploration and knowledge extraction as focused on HCV. A list of 32,895 abstracts retrieved via PubMed database using specific keywords searches related to HCV were processed based on concept recognition of terms from several dictionaries. The web query interface enables retrieval of information using specified concepts, keywords and phrases, generating text-derived association networks and hypotheses, which could be tested to identify potentially novel relationship between different concepts. Such an approach could also augment efforts in the search for diagnostic or even therapeutic targets. DESHCV thus represents online literature-based discovery resource freely accessible for academic and non-profit users via http://apps.sanbi.ac.za/DESHCV/ and its mirror site http://cbrc.kaust.edu.sa/deshcv/.

Serum lipids in European chronic HCV genotype 1 patients during and after treatment with pegylated interferon-α-2a and ribavirin

AIMS

Chronic hepatitis C alters the host's lipid metabolism and hepatitis C virus (HCV) eradication may be followed by an increase of serum cholesterol to adverse levels. We therefore aimed to determine the impact of chronic hepatitis C and its treatment on circulating lipids in a large European cohort of HCV genotype 1 patients.

METHODS

The serum lipid profile of 575 HCV genotype 1-infected patients was characterized before, during and after treatment with pegylated interferon-α-2a (180 μg/week) and ribavirin (1000-1200 mg/day) for 48 weeks within a randomized controlled clinical trial.

RESULTS

Total baseline cholesterol levels were significantly higher in patients with sustained virologic response (SVR) compared to nonresponders/relapsers (177 vs. 167 mg/dl, P=0.01), and low-cholesterol levels were an independent negative predictor of SVR (P=0.084). During the antiviral treatment, cholesterol levels substantially decreased as a putative marker of interferon-activity, but rebounded above baseline in patients with SVR (177-188 mg/dl, P=0.02), and to baseline in nonresponders/relapsers. Proportions of patients with cholesterol (>240 mg/dl) at baseline and after HCV eradication were 4 and 6%, respectively. Significant differences of triglyceride levels in patients with and without SVR were only observed at follow-up (136 and 117 mg/dl, respectively, P=0.028) but not at baseline.

CONCLUSION

Our study reports a substantial pretreatment hypocholesterolemia in European HCV genotype 1 patients with nonresponse to interferon-α-based therapy and lower pretreatment cholesterol levels were an independent predictor of not attaining SVR. After treatment-induced HCV eradication median cholesterol levels increased above baseline, but the proportion of patients with high-risk cholesterol levels remained relatively low.

Influence of amantadine on CD81 expression on lymphocytes in chronic hepatitis C

INTRODUCTION

Interferon alpha (IFN) down regulates CD81 expression on peripheral blood mononuclear cells (PBMC) in patients with chronic hepatitis C virus (HCV) infection. Aim of our study was to investigate whether amantadine alters IFN associated down regulation of CD81 expression on PBMC in patients with chronic hepatitis C.

METHODS

Nineteen patients with chronic HCV infection received peginterferon alpha-2a/ribavirin (SOC) for 48 weeks. Patients were randomised to 12 weeks amantadine therapy (n=12) or no additional treatment (n=7). FACS analysis of CD81 expression on CD4(+), CD8(+), CD19(+), and CD56(+) cells was performed at baseline, week (TW) 4, TW12, and TW24 of antiviral therapy.

RESULTS

A significant decline of CD81 expression was observed on CD4(+), CD8(+), and CD56(+) cells (p=0.011, p<0.001, p=0.015, respectively) but not on CD19(+) cells (p>0.2). CD81 expression on CD4(+), CD8(+), CD19(+), and CD56(+) cells was not different between patients treated with SOC plus amantadine and patients treated with SOC alone.

CONCLUSION

The current study confirms that CD81 expression is down regulated by SOC on CD4(+), CD8(+) and CD56(+) cells. Amantadine treatment was not associated with CD81 expression. Interaction between amantadine and CD81 is unlikely to be involved in potential antiviral activity of amantadine in chronic HCV infection.

Hepatitis C virus p7-a viroporin crucial for virus assembly and an emerging target for antiviral therapy

The hepatitis C virus (HCV), a hepatotropic plus-strand RNA virus of the family Flaviviridae, encodes a set of 10 viral proteins. These viral factors act in concert with host proteins to mediate virus entry, and to coordinate RNA replication and virus production. Recent evidence has highlighted the complexity of HCV assembly, which not only involves viral structural proteins but also relies on host factors important for lipoprotein synthesis, and a number of viral assembly co-factors. The latter include the integral membrane protein p7, which oligomerizes and forms cation-selective pores. Based on these properties, p7 was included into the family of viroporins comprising viral proteins from multiple virus families which share the ability to manipulate membrane permeability for ions and to facilitate virus production. Although the precise mechanism as to how p7 and its ion channel function contributes to virus production is still elusive, recent structural and functional studies have revealed a number of intriguing new facets that should guide future efforts to dissect the role and function of p7 in the viral replication cycle. Moreover, a number of small molecules that inhibit production of HCV particles, presumably via interference with p7 function, have been reported. These compounds should not only be instrumental in increasing our understanding of p7 function, but may, in the future, merit further clinical development to ultimately optimize HCV-specific antiviral treatments.

Intracellular proton conductance of the hepatitis C virus p7 protein and its contribution to infectious virus production

The hepatitis C virus (HCV) p7 protein is critical for virus production and an attractive antiviral target. p7 is an ion channel when reconstituted in artificial lipid bilayers, but channel function has not been demonstrated in vivo and it is unknown whether p7 channel activity plays a critical role in virus production. To evaluate the contribution of p7 to organelle pH regulation and virus production, we incorporated a fluorescent pH sensor within native, intracellular vesicles in the presence or absence of p7 expression. p7 increased proton (H(+)) conductance in vesicles and was able to rapidly equilibrate H(+) gradients. This conductance was blocked by the viroporin inhibitors amantadine, rimantadine and hexamethylene amiloride. Fluorescence microscopy using pH indicators in live cells showed that both HCV infection and expression of p7 from replicon RNAs reduced the number of highly acidic (pH<5) vesicles and increased lysosomal pH from 4.5 to 6.0. These effects were not present in uninfected cells, sub-genomic replicon cells not expressing p7, or cells electroporated with viral RNA containing a channel-inactive p7 point mutation. The acidification inhibitor, bafilomycin A1, partially restored virus production to cells electroporated with viral RNA containing the channel inactive mutation, yet did not in cells containing p7-deleted RNA. Expression of influenza M2 protein also complemented the p7 mutant, confirming a requirement for H(+) channel activity in virus production. Accordingly, exposure to acid pH rendered intracellular HCV particles non-infectious, whereas the infectivity of extracellular virions was acid stable and unaffected by incubation at low pH, further demonstrating a key requirement for p7-induced loss of acidification. We conclude that p7 functions as a H(+) permeation pathway, acting to prevent acidification in otherwise acidic intracellular compartments. This loss of acidification is required for productive HCV infection, possibly through protecting nascent virus particles during an as yet uncharacterized maturation process.

A randomized controlled trial of double versus triple therapy with amantadine for genotype 1 chronic hepatitis C in Latino patients

BACKGROUND

With only a third of Latinos achieving sustained virologic response (SVR), there is a need for enhanced HCV treatment. Amantadine has been proposed to improve response rates in addition to standard therapy with peginterferon alpha and ribavirin. Our objective is to evaluate whether triple therapy with amantadine improves SVR rates in this special population.

METHOD

Treatment-naïve Latino subjects with HCV genotype 1 infection were randomized to receive peginterferon alpha-2a plus weight-based ribavirin for 48 weeks (double therapy) or the same regimen plus amantadine 200 mg daily (triple therapy). The primary endpoint was SVR. Predictors of liver fibrosis using APRI and Forns indices were also evaluated.

RESULTS

We enrolled 124 patients with chronic hepatitis C genotype 1. Sixty-three received conventional therapy and 61 patients had triple therapy with amantadine. SVR at week 72 was achieved in 25 patients (39.7%) vs. 26 patients (42.6%) in the double and triple regimen, respectively (p=0.561). After multivariate analysis, advanced fibrosis, obesity, and low pretreatment ALT levels were associated with non-response in both groups (p=0.0234, p=0.0012, p=0.0249, respectively). APRI values delimited an area under the ROC curve (AUROC) of 0.724 and Forns index with AUROC of 0.733. There was no difference between both indices in predicting significant fibrosis (Knodell index: F3-F4).

CONCLUSION

Our study demonstrates that the addition of amantadine to standard treatment of chronic HCV does not improve SVR rates in Latino patients with genotype 1. Further research to improve response rates in this special population is needed.

Know your enemy: translating insights about the molecular biology of hepatitis C virus into novel therapeutic approaches

Identified in 1989 as the cause of what was then known as hepatitis non-A non-B, the hepatitis C virus (HCV) continues to be a significant global public health threat, given that an estimated 123 million individuals are chronically infected and, thus, at risk for cirrhosis and hepatocellular carcinoma. After 20 years of basic and clinical research into HCV infection, the backbone of therapy has remained interferon, a drug that - in a different formulation - was already being employed before HCV was even identified. Nonetheless, research has overcome many obstacles that stood in the way of studying this pre-eminent human pathogen. Hard-won insights into its molecular biology have identified promising therapeutic targets, and we are now on the verge of an era where rationally designed therapeutics, also referred to as specifically targeted antiviral therapy for HCV, will reshape the treatment of hepatitis C. This article describes recent insights on the molecular biology of HCV and the efforts to translate them into clinical applications.

Clinical trial: a randomized trial of pegylated-interferon-alpha-2a plus ribavirin with or without amantadine in treatment-naïve or relapsing chronic hepatitis C patients

BACKGROUND

The combination therapy of pegylated-interferon-alpha2a plus ribavirin is considered as the standard of care for patients with chronic hepatitis C. A sustained viral response is obtained in 40-50% of naïve patients with genotype 1 and in around 80% of naïve patients with genotype 2 or 3.

AIM

To assess whether amantadine, added to the conventional combination therapy, could improve the treatment efficacy.

METHODS

In all, 630 patients (intent-to-treat population) with chronic hepatitis C were randomized into two groups: 316 patients (treatment group) received pegylated-interferon-alpha2a (180 microg once weekly) plus ribavirin (1000-1200 mg/daily) with amantadine (200 mg/daily); 314 patients (control group) received pegylated-interferon-alpha2a (180 microg once weekly) plus ribavirin (1000-1200 mg/daily) without amantadine. The duration of the treatment was 48 weeks for genotypes 1, 4, 5 and 6, and 24 weeks for genotypes 2 and 3.

RESULTS

There was no statistically significant difference between treatments groups for any of the variables tested for. Subgroups of patients likely to take advantage of the addition of amantadine were not identified.

CONCLUSIONS

This large study definitely excludes the role of amantadine in addition of conventional combination therapy in the treatment of chronic hepatitis C patients.

Another ten stories in antiviral drug discovery (part C): "Old" and "new" antivirals, strategies, and perspectives

The ten stories told here deal with (i) ribavirin as an inhibitor of IMP dehydrogenase and (ii) ribavirin, in combination with pegylated interferon, as the present "standard of care" for hepatitis C; (iii) S-adenosylhomocysteine hydrolase inhibitors as antiviral agents; (iv) new adamantadine derivatives for the treatment of influenza A virus infections; (v) 5-substituted 2'-deoxyuridines (i.e. IDU, TFT) for the treatment of herpes simplex virus (HSV) infections; (vi) acyclic guanosine analogues (e.g. acyclovir) for the treatment of HSV infections; (vii) OMP decarboxylase inhibitors (i.e. pyrazofurin) and CTP synthetase inhibitors (i.e. cyclopentenylcytosine) as possible antiviral agents; (viii) the future of cidofovir (and alkoxyalkyl esters thereof) and ST-246 as potential antipoxvirus agents; (ix) the two decade journey from tivirapine to rilpivirine in the ultimate therapy of HIV infections; and (x) the extension of the therapeutic application of tenofovir disoproxil fumarate (Viread) to the treatment of hepatitis B virus infection, in addition to HIV infection.