Description: Objective Insulin resistance is a predictor of poor response to peginterferon/ribavirin in patients infected with the chronic hepatitis C virus (HCV). There are no data on direct-acting antivirals. This exploratory analysis assessed the effect of metabolic factors and insulin resistance, measured by homoeostatic model assessment (HOMA), on virological response to telaprevir in Study C208. Design Overall, 161 HCV genotype 1-infected, treatment-naïve patients received 12 weeks of telaprevir plus peginterferon/ribavirin, then 12/36 weeks of peginterferon/ribavirin depending on on-treatment response criteria. The prognostic significance of several factors, including HOMA-insulin resistance (HOMA-IR), on virological response at weeks 4 and 12, end of treatment and 24 weeks after treatment was explored by multiple regression analysis. Results Baseline HOMA-IR data were available for 147 patients; baseline characteristics were consistent with the overall population. Baseline HOMA-IR 〈2, 2–4 and 〉4 was seen in 54%, 30% and 16% of patients, respectively. Neither response rates (any time point) nor week 4 viral load decline were significantly influenced by baseline HOMA-IR. In multivariate analyses, fibrosis stage and low-density lipoprotein cholesterol level were predictive of sustained virological response (OR 0.47 and 1.02, respectively). After the end of treatment, HOMA-IR was significantly lower in patients with sustained virological response than in those without (0.61 vs 1.34 for relapsers and 1.15 for non-responders; p〈0.05). Conclusion In this study, baseline HOMA-IR was not predictive of virological response to telaprevir in HCV genotype 1-infected, treatment-naïve patients, while sustained virological response was associated with improved HOMA-IR. These results suggest that metabolic factors and insulin resistance do not have a significant effect on telaprevir-based treatment efficacy.

Description: Serine is encoded by two divergent codon types, UCN and AGY, which are not interchangeable by a single nucleotide substitution. Switching between codon types therefore occurs via intermediates (threonine or cysteine) or via simultaneous tandem substitutions. Hepatitis C virus (HCV) chronically infects 2 to 3% of the global population. The highly variable glycoproteins E1 and E2 decorate the surface of the viral envelope, facilitate cellular entry, and are targets for host immunity. Comparative sequence analysis of globally sampled E1E2 genes, coupled with phylogenetic analysis, reveals the signatures of multiple archaic codon-switching events at seven highly conserved serine residues. Limited detection of intermediate phenotypes indicates that associated fitness costs restrict their fixation in divergent HCV lineages. Mutational pathways underlying codon switching were probed via reverse genetics, assessing glycoprotein functionality using multiple in vitro systems. These data demonstrate selection against intermediate phenotypes can act at the structural/functional level, with some intermediates displaying impaired virion assembly and/or decreased capacity for target cell entry. These effects act in residue/isolate-specific manner. Selection against intermediates is also provided by humoral targeting, with some intermediates exhibiting increased epitope exposure and enhanced neutralization sensitivity, despite maintaining a capacity for target cell entry. Thus, purifying selection against intermediates limits their frequencies in globally sampled strains, with divergent functional constraints at the protein level restricting the fixation of deleterious mutations. Overall our study provides an experimental framework for identification of barriers limiting viral substitutional evolution and indicates that serine codon-switching represents a genomic "fossil record" of historical purifying selection against E1E2 intermediate phenotypes.

Description: Introduction Since the discovery of HCV in 1989, interferon α (IFNα)-based therapy has been the only treatment approach leading to HCV genotype-dependent sustained virological response (SVR) rates in a significant number of patients. However, the treatment uptake has been generally low due to numerous side effects and contraindications to IFNα-based regimens. Because of these limitations, the overall HCV-related health burden could only gradually be decreased, even though treatment efficacy was increased over recent years. 1 2 The lack of cell culture systems to grow HCV had been a key limitation for the development of direct acting antivirals (DAAs). Nevertheless, in 1997, only a few years after the discovery of HCV, the first subgenomic HCV replicons were obtained allowing researchers to develop and assay DAAs with a robust methodology. 3 – 5 In 2004, the safety and efficacy of the first DAA, the protease inhibitor...

Description: Hepatitis C virus (HCV) infection is a major biomedical problem worldwide as it causes severe liver disease in millions of humans around the world. Despite the recent approval of specific drugs targeting HCV replication to be used in combination with alpha interferon (IFN-α) and ribavirin, there is still an urgent need for pangenotypic, interferon-free therapies to fight this genetically diverse group of viruses. In this study, we used an unbiased screening cell culture assay to interrogate a chemical library of compounds approved for clinical use in humans. This system enables identifying nontoxic antiviral compounds targeting every aspect of the viral life cycle, be the target viral or cellular. The aim of this study was to identify drugs approved for other therapeutic applications in humans that could be effective components of combination therapies against HCV. As a result of this analysis, we identified 12 compounds with antiviral activity in cell culture, some of which had previously been identified as HCV inhibitors with antiviral activity in cell culture and had been shown to be effective in patients. We selected two novel HCV antivirals, hydroxyzine and benztropine, to characterize them by determining their specificity and genotype spectrum as well as by defining the step of the replication cycle targeted by these compounds. We found that both compounds effectively inhibited viral entry at a postbinding step of genotypes 1, 2, 3, and 4 without affecting entry of other viruses.