Development of novel treatments for hepatitis C

LC3B is not recruited along with the autophagy elongation complex (ATG5-12/16L1) at HCV replication site and is dispensable for viral replication

Hepatitis C virus (HCV) infection is known to induce autophagosome accumulation as observed by the typical punctate cytoplasmic distribution of LC3B-II in infected cells. Previously, we showed that viral RNA-dependent RNA polymerase (NS5B) interacts with ATG5, a major component of the autophagy elongation complex that is involved in the formation of double-membrane vesicles (DMV), and demonstrated that the autophagy elongation complex (ATG5-12/16L1) but not LC3B is required for proper membranous web formation. In this study, the colocalization and in situ interaction of all HCV replicase components with the constituent of the autophagy elongation complex and LC3B were analyzed. The results clearly show the recruitment of the elongation complex to the site of viral replication. Using in situ proximity ligation assay, we show that ATG5, but not ATG16L1, interacts with several HCV replicase components suggesting that the recruitment is directed via the ATG5-12 conjugate. Interestingly, no E3-like conjugation activity of ATG5-12/16L1 can be detected at the at HCV replication site since LC3B-II is not found along with the elongation complex at the site of viral replication. In agreement with this result, no sign of in situ interaction of LC3B with the replicase components is observed. Finally, using dominant negative forms of ATG proteins, we demonstrate that ATG5-12 conjugate, but not LC3-II formation, is critical for viral replication. Altogether, these findings suggest that although HCV needs the elongation complex for its replication, it has developed a mechanism to avoid canonical LC3-II accumulation at viral replication site.

Liver Illness and Psoriatic Patients

Psoriasis is a chronic inflammatory disease of the skin affecting approximately 2% of the world's population. Systemic treatments, including methotrexate and cyclosporin, are associated with potential hepatotoxicity, due to either direct liver damage or immunosuppression or both immunomediated and a direct liver injury; therefore, treatment of patients with psoriasis poses a therapeutic challenge. The aim of this minireview is to help clinicians in the management of psoriatic patients who develop signs of liver dysfunction. To find relevant articles, a comprehensive search was performed on PubMed, EMBASE, and Cochrane with appropriate combinations of the following keywords being considered: viral hepatitis, nonalcoholic fatty liver disease, psoriasis, hepatotoxicity, drug toxicity, cholestasis, and autoimmune liver diseases.

Identification and Analysis of Novel Inhibitors against NS3 Helicase and NS5B RNA-Dependent RNA Polymerase from Hepatitis C Virus 1b (Con1)

Hepatitis C virus (HCV) leads to severe liver diseases, including liver fibrosis, cirrhosis and hepatocellular carcinoma. Non-structural protein 3 helicase (NS3h) and non-structural protein 5B RNA-dependent RNA polymerase (NS5B) are involved in the replication of HCV RNA genome, and have been proved to be excellent targets for discovery of direct-acting antivirals. In this study, two high-throughput screening systems, fluorescence polarization (FP)-based ssDNA binding assay and fluorescence intensity (FI)-based dsRNA formation assay, were constructed to identify candidate NS3h and NS5B inhibitors, respectively. A library of approximately 800 small molecules and crude extracts, derived from marine microorganisms or purchased from the National Compound Resource Center, China, were screened, with three hits selected for further study. Natural compound No.3A5, isolated from marine fungi, inhibited NS3h activity with an IC₅₀ value of 2.8 μM. We further demonstrated that compound No.3A5 inhibited the abilities of NS3h to bind ssDNA in electrophoretic mobility shift assay and to hydrolyze ATP. The NS3h-inhibitory activity of compound No.3A5 was reversible in our dilution assay, which indicated there was no stable NS3h-No.3A5 complex formed. Additionally, compound No.3A5 exhibited no binding selectivity on NS3h or single strand binding protein of Escherichia coli. In NS5B assays, commercial compounds No.39 and No.94 previously reported as kinase inhibitors were found to disrupt dsRNA formation, and their IC₅₀ values were 62.9 and 18.8 μM, respectively. These results highlight how identifying new uses for existing drugs is an effective method for discovering novel HCV inhibitors. To our knowledge, all inhibitors reported in this study were originally discovered with HCV anti-non-structural protein activities in vitro.

Current therapy for chronic hepatitis C: The role of direct-acting antivirals

One of the most exciting developments in antiviral research has been the discovery of the direct-acting antivirals (DAAs) that effectively cure chronic hepatitis C virus (HCV) infections. Based on more than 100 clinical trials and real-world studies, we provide a comprehensive overview of FDA-approved therapies and newly discovered anti-HCV agents with a special focus on drug efficacy, mechanisms of action, and safety. We show that HCV drug development has advanced in multiple aspects: (i) interferon-based regimens were replaced by interferon-free regimens; (ii) genotype-specific drugs evolved to drugs for all HCV genotypes; (iii) therapies based upon multiple pills per day were simplified to a single pill per day; (iv) drug potency increased from moderate (∼60%) to high (>90%) levels of sustained virologic responses; (v) treatment durations were shortened from 48 to 12 or 8 weeks; and (vi) therapies could be administered orally regardless of prior treatment history and cirrhotic status. However, despite these remarkable achievements made in HCV drug discovery, challenges remain in the management of difficult-to-treat patients.

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HCV genotype-specific drugs evolve to pan-genotypic drugs.

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Drug potency increases from moderate (∼60%) to high (>90%) levels of sustained virologic response.

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Treatment durations are shortened from a 48-week to 12-week or 8-week period.

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HCV therapies based upon multiple pills per day are simplified to a single pill per day.

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HCV therapies are administered orally regardless of prior treatment history and cirrhotic status.

The autophagy elongation complex (ATG5-12/16L1) positively regulates HCV replication and is required for wild-type membranous web formation

Hepatitis C virus (HCV) infection induces intracellular membrane rearrangements, thus forming a membranous web (MW) in which HCV replication and assembly occur. The HCV-induced MW is primarily composed of double membrane vesicles (DMVs) transfused by multi-membrane vesicles. The autophagy machinery has been proposed to participate in the formation of such vesicles. However, no clear evidence has been found linking autophagy to the formation of these DMVs. In this study, we evaluated the role of the autophagy elongation complex (ATG5-12/16L1) in HCV replication and MW formation. Using a dominant negative form of ATG12 and an siRNA approach, we demonstrated that the ATG5-12 conjugate, but not LC3-II formation, is crucial for efficient viral replication. Furthermore, purification of HCV MW revealed the presence of ATG5-12 and ATG16L1 along with HCV nonstructural proteins. Interestingly, LC3 was not recruited along with the elongation complex to the site of viral replication. Finally, inhibition of the elongation complex, but not LC3, greatly impaired the formation of the wild-type MW phenotype. To our knowledge, this study provides the first evidence of the involvement of autophagy proteins in the formation of wild-type MWs.

Task-based optimization of flip angle for fibrosis detection in T1-weighted MRI of liver

Chronic liver disease is a worldwide health problem, and hepatic fibrosis (HF) is one of the hallmarks of the disease. The current reference standard for diagnosing HF is biopsy followed by pathologist examination; however, this is limited by sampling error and carries a risk of complications. Pathology diagnosis of HF is based on textural change in the liver as a lobular collagen network that develops within portal triads. The scale of collagen lobules is characteristically in the order of 1 to 5 mm, which approximates the resolution limit of in vivo gadolinium-enhanced magnetic resonance imaging in the delayed phase. We use MRI of formalin-fixed human ex vivo liver samples as phantoms that mimic the textural contrast of in vivo Gd-MRI. We have developed a local texture analysis that is applied to phantom images, and the results are used to train model observers to detect HF. The performance of the observer is assessed with the area-under-the-receiver-operator-characteristic curve (AUROC) as the figure-of-merit. To optimize the MRI pulse sequence, phantoms were scanned with multiple times at a range of flip angles. The flip angle that was associated with the highest AUROC was chosen as optimal for the task of detecting HF.

In Silico Design and Experimental Validation of siRNAs Targeting Conserved Regions of Multiple Hepatitis C Virus Genotypes

RNA interference (RNAi) is a post-transcriptional gene silencing mechanism that mediates the sequence-specific degradation of targeted RNA and thus provides a tremendous opportunity for development of oligonucleotide-based drugs. Here, we report on the design and validation of small interfering RNAs (siRNAs) targeting highly conserved regions of the hepatitis C virus (HCV) genome. To aim for therapeutic applications by optimizing the RNAi efficacy and reducing potential side effects, we considered different factors such as target RNA variations, thermodynamics and accessibility of the siRNA and target RNA, and off-target effects. This aim was achieved using an in silico design and selection protocol complemented by an automated MysiRNA-Designer pipeline. The protocol included the design and filtration of siRNAs targeting highly conserved and accessible regions within the HCV internal ribosome entry site, and adjacent core sequences of the viral genome with high-ranking efficacy scores. Off-target analysis excluded siRNAs with potential binding to human mRNAs. Under this strict selection process, two siRNAs (HCV353 and HCV258) were selected based on their predicted high specificity and potency. These siRNAs were tested for antiviral efficacy in HCV genotype 1 and 2 replicon cell lines. Both in silico-designed siRNAs efficiently inhibited HCV RNA replication, even at low concentrations and for short exposure times (24h); they also exceeded the antiviral potencies of reference siRNAs targeting HCV. Furthermore, HCV353 and HCV258 siRNAs also inhibited replication of patient-derived HCV genotype 4 isolates in infected Huh-7 cells. Prolonged treatment of HCV replicon cells with HCV353 did not result in the appearance of escape mutant viruses. Taken together, these results reveal the accuracy and strength of our integrated siRNA design and selection protocols. These protocols could be used to design highly potent and specific RNAi-based therapeutic oligonucleotide interventions.

Functional foods effective for hepatitis C: Identification of oligomeric proanthocyanidin and its action mechanism

Hepatitis C virus (HCV) is a major cause of viral hepatitis and currently infects approximately 170 million people worldwide. An infection by HCV causes high rates of chronic hepatitis (> 75%) and progresses to liver cirrhosis and hepatocellular carcinoma ultimately. HCV can be eliminated by a combination of pegylated α-interferon and the broad-spectrum antiviral drug ribavirin; however, this treatment is still associated with poor efficacy and tolerability and is often accompanied by serious side-effects. While some novel direct-acting antivirals against HCV have been developed recently, high medical costs limit the access to the therapy in cost-sensitive countries. To search for new natural anti-HCV agents, we screened local agricultural products for their suppressive activities against HCV replication using the HCV replicon cell system in vitro. We found a potent inhibitor of HCV RNA expression in the extracts of blueberry leaves and then identified oligomeric proanthocyanidin as the active ingredient. Further investigations into the action mechanism of oligomeric proanthocyanidin suggested that it is an inhibitor of heterogeneous nuclear ribonucleoproteins (hnRNPs) such as hnRNP A2/B1. In this review, we presented an overview of functional foods and ingredients efficient for HCV infection, the chemical structural characteristics of oligomeric proanthocyanidin, and its action mechanism.

Safety and efficacy of Hansenula-derived PEGylated-interferon alpha-2a and ribavirin combination in chronic hepatitis C Egyptian children

AIM: To investigate the safety and efficacy of a Hansenula-derived PEGylated (polyethylene glycol) interferon (IFN)-alpha-2a (Reiferon Retard) plus ribavirin customized regimen in treatment-naïve and previously treated (non-responders and relapsers) Egyptian children with chronic hepatitis C infection.

METHODS: Forty-six children with chronic hepatitis C virus (HCV) infection were selected from three tertiary pediatric hepatology centers. Clinical and laboratory evaluations were undertaken. Quantitative polymerase chain reaction (PCR) for HCV-RNA was performed before starting treatment, and again at 4, 12, 24, 48, 72 wk during treatment and 6 mo after treatment cessation. All patients were assigned to receive a weekly subcutaneous injection of PEG-IFN-alpha-2a plus daily oral ribavirin for 12 wk. Thirty-four patients were treatment-naïve and 12 had a previous treatment trial. Patients were then divided according to PCR results into two groups. Group I included patients who continued treatment on a weekly basis (7-d schedule), while group II included patients who continued treatment on a 5-d schedule. Patients from either group who were PCR-negative at week 48, but had at least one PCR-positive test during therapy, were assigned to have an extended treatment course up to 72 wk. The occurrence of adverse effects was assessed during treatment and follow up. The study was registered at www.ClinicalTrials.gov (NCT02027493).

RESULTS: Only 11 out of 46 (23.9%) patients showed a sustained virological response (SVR), two patients were responders at the end of treatment; however, they were lost to follow up at 6 mo post treatment. Breakthrough was seen in 18 (39.1%) patients, one patient (2.17%) showed relapse and 14 (30.4%) were non-responders. Male gender, short duration of infection, low viral load, mild activity, and mild fibrosis were the factors related to a better response. On the other hand, patients with high viral load and absence of fibrosis failed to respond to treatment. Before treatment, liver transaminases were elevated. After commencing treatment, they were normalized in all patients at week 4 and were maintained normal in responders till the end of treatment, while they increased again significantly in non-responders (P = 0.007 and 0.003 at week 24 and 72 respectively). The 5-d schedule did not affect the response rate (1/17 had SVR). Treatment duration (whether 48 wk or extended course to 72 wk) gave similar response rates (9/36 vs 2/8 respectively; P = 0.49). Type of previous treatment (short acting IFN vs PEG-IFN) did not affect the response to retreatment. On the other hand, SVR was significantly higher in previous relapsers than in previous non-responders (P = 0.039). Only mild reversible adverse effects were observed and children tolerated the treatment well.

CONCLUSION: Reiferon Retard plus ribavirin combined therapy was safe. Our customized regimen did not influence SVR rates. Further trials on larger numbers of patients are warranted.

Development of murine models to study Hepatitis C virus induced liver pathogenesis

Hepatitis C virus (HCV) is involved in different liver pathologies worldwide. In contemporary scenario, HCV treatment is lagging behind owing to absence of vaccines against virus. The only consideration for HCV treatment is pegylated interferon-alpha and ribavirin that results in sustained virological response in 50 % of patients. Two feasible hosts for HCV infection are chimpanzee and humans. For decades, chimpanzees are sole host to study HCV pathogenesis, but their use is limited due to ethical issues. The dilemma behind HCV therapy is the need of sustainable animal models that can help simulate in vivo conditions. We have assembled recent advances in animal models to study liver diseases for targeted therapy.

Development of boceprevir: a first-in-class direct antiviral treatment for chronic hepatitis C infection

The identification of hepatitis C virus (HCV) as the causative agent of non-A and non-B hepatitis, over 20 years ago, fueled an intensive effort to develop direct-acting antivirals targeting the viral polymerase and protease, two key proteins critical for HCV replication. However, it took more than two decades for these efforts to be realized with boceprevir, one of the two HCV protease inhibitors approved for treatment of HCV infection in 2011. The development of boceprevir is a major advancement in the ability to treat HCV infection and a significant step toward the long-term goal of eradicating chronic HCV infection. Both as a first-in-class agent and an entirely new modality for treating HCV infection, many challenges were encountered during the discovery and development of this compound. The lessons learned in overcoming these obstacles offer insights and pave the way for the newly emerging field of HCV antiviral therapeutics. This paper will describe the discovery and development of a first-in-class direct antiviral treatment for chronic hepatitis C infection, boceprevir, marketed around the world as Victrelis™.

Serum complement C4a and its relation to liver fibrosis in children with chronic hepatitis C

AIM: To evaluate serum complement C4a and its relation to liver fibrosis in children with chronic hepatitis C virus (HCV) infection.

METHODS: The study included 30 children with chronic HCV infection before receiving antiviral therapy. Chronic HCV infection was defined by positive anti-HCV, a positive polymerase chain reaction for HCV-RNA for more than 6 mo with absence of any associated liver disease. A second group of 30 age- and sex-matched healthy children served as controls. Serum C4a levels were measured by enzyme-linked immunosorbent assay. Liver fibrosis stage and inflammatory grade were assessed using Ishak scoring system. Serum C4a levels were compared according to different clinical, laboratory and histopathological parameters. Statistical significance for quantitative data was tested by Mann-Whitney U non-parametric tests. For qualitative data, significance between groups was tested by χ² test. Correlation was tested by Spearman’s test. Results were considered significant if P value ≤ 0.05.

RESULTS: The age of the patients ranged from 3.5 to 18 years and that of controls ranged from 4 to 17 years. C4a mean levels were merely lower in patients (153.67 ± 18.69 mg/L) than that in the controls (157.25 ± 11.40 mg/L) with no statistical significance (P = 0.378). It did not differ significantly in patients with elevated vs those with normal transaminases (152.25 ± 16.62 vs 155.36 ± 21.33; P = 0.868) or with different HCV viremia (P = 0.561). Furthermore, there was no statistical significant difference in serum levels between those with no/mild fibrosis and those with moderate fibrosis (154.65 ± 20.59 vs 152.97 ± 17.72; P = 0.786) or minimal and mild activity (155.1 ± 21.93 vs 152.99 ± 17.43; P = 0.809). Though statistically not significant, C4a was highest in fibrosis score 0 (F0), decreasing in F1 and F2 to be the lowest in F3. When comparing significant fibrosis (Ishak score ≥ 3) vs other stages, C4a was significantly lower in F3 compared to other fibrosis scores (143.55 ± 2.33 mg/L vs 155.26 ± 19.64 mg/L; P = 0.047) and at a cutoff value of less than 144.01 mg/L, C4a could discriminate F3 with 76.9% sensitivity and 75% specificity from other stages of fibrosis.

CONCLUSION: Serum complement C4a did not correlate with any of transaminases, HCV viremia or with the histopathological scores. Although C4a decreased with higher stages of fibrosis, this change was not significant enough to predict individual stages of fibrosis. Yet, it could predict significant fibrosis with acceptable clinical performance.

Association between XRCC1 Arg399Gln polymorphism and hepatitis virus-related hepatocellular carcinoma risk in Asian population

To investigate the association between X-ray repair cross-complementing group 1 (XRCC1) Arg399Gln polymorphism and hepatitis virus-related hepatocellular carcinoma risk, we performed a systematic meta-analysis of eligible case-control studies. Eligible studies were identified from the PubMed, Embase, and Chinese National Knowledge Infrastructure databases up to March 2013. The odds ratios (ORs) and corresponding 95 % confidence interval (95 % CI) of XRCC1 Arg399Gln polymorphism in hepatitis virus-related hepatocellular carcinoma cases compared with those in controls were calculated. The meta-analysis was performed using fixed-effect or random-effect methods according to the absence or presence of heterogeneity. This meta-analysis included 1,558 cases with hepatitis virus-related hepatocellular carcinoma and 1,338 controls. Meta-analysis of available data showed that there was no association between XRCC1 Arg399Gln polymorphism and risk of hepatitis virus-related hepatocellular carcinoma under all contrast models (Gln vs. Arg: fixed-effect OR = 0.92, 95 % CI 0.82-1.04, P = 0.18; GlnGln vs. ArgArg: random-effect OR = 0.79, 95 % CI 0.50-1.25, P = 0.32; GlnGln/ArgGln vs. ArgArg: fixed-effect OR = 0.92, 95 % CI 0.79-1.07, P = 0.28; and GlnGln vs. ArgArg/ArgGln: random-effect OR = 0.83, 95 % CI 0.52-1.34, P = 0.45). Sensitivity analysis further showed that there was no association between XRCC1 Arg399Gln polymorphism and risk of hepatitis B-related hepatocellular carcinoma under all contrast models (Gln vs. Arg: fixed-effect OR = 0.93, 95 % CI 0.82-1.05, P = 0.25; GlnGln vs. ArgArg: fixed-effect OR = 0.86, 95 % CI 0.64-1.16, P = 0.32; GlnGln/ArgGln vs. ArgArg: fixed-effect OR = 0.93, 95 % CI 0.80-1.10, P = 0.41; and GlnGln vs. ArgArg/ArgGln: fixed-effect OR = 0.85, 95 % CI 0.63-1.13, P = 0.26). Our meta-analysis of the available data did not find an obvious effect of XRCC1 Arg399Gln polymorphism on hepatitis-related hepatocellular carcinoma. More well-designed studies with large sample are needed to further verify the effect.

Stapled peptide-based membrane fusion inhibitors of hepatitis C virus

The strategy of peptide stapling was used to develop new molecules to inhibit the hepatitis C virus infection via disrupting the binding of HCV envelope glycoprotein E2 with human cell surface protein CD81. The peptide sequence was designed based on the large extra-cellular loop of CD81 with known importance in the HCV E2 binding interaction. Our results showed that the stapled peptides exhibited significantly higher α-helicity and proteolytic stability as compared to their linear peptide counterpart. The optimal compound was found to have an EC50 value of ca. 17-39μM against different HCV subtypes and represented a new HCV membrane fusion inhibitor.

Ribavirin-induced externalization of phosphatidylserine in erythrocytes is predominantly caused by inhibition of aminophospholipid translocase activity

Ribavirin in combination with interferon-α is the standard treatment for chronic hepatitis C, but often induces severe anemia forcing discontinuation of the therapy. Whereas suppression of bone marrow by interferon may impact on the production of erythrocytes, it has been suggested that accumulation of ribavirin in erythrocytes induces alterations causing an early removal of these cells by the mononuclear phagocytic system. Externalization of phosphatidylserine, which is exclusively present in the cytoplasmic leaflet of the plasma membrane, is a recognition signal for phagocytosis in particular of apoptotic cells. Here, we demonstrate that surface exposure of phosphatidylserine upon prolonged treatment of erythrocytes with ribavirin results mainly from inactivation of the aminophospholipid translocase, an ATP-dependent lipid pump, which specifically transports phosphatidylserine from the outer to the inner leaflet of the plasma membrane. Inactivation is due to severe ATP depletion, although competitive inhibition by ribavirin or its phosphorylated derivatives cannot be excluded. Phospholipid scramblase, responsible for collapse of lipid asymmetry, appears to be of minor importance as erythrocytes of patients with the Scott syndrome, lacking Ca(2+)-induced lipid scrambling, are equally sensitive to ribavirin treatment. Neither the antioxidant N-acetylcysteine nor the pan-caspase inhibitor Q-VD-OPH did affect ribavirin-induced phosphatidylserine exposure, suggesting that oxidative stress or apoptotic-related mechanisms are not involved in this process. In conclusion, we propose that spontaneous loss of lipid asymmetry, not corrected by aminophospholipid translocase activity, is the mechanism for ribavirin-induced phosphatidylserine exposure that may contribute to ribavirin-induced anemia.

Signaling in innate immunity and inflammation

Inflammation is triggered when innate immune cells detect infection or tissue injury. Surveillance mechanisms involve pattern recognition receptors (PRRs) on the cell surface and in the cytoplasm. Most PRRs respond to pathogen-associated molecular patterns (PAMPs) or host-derived damage-associated molecular patterns (DAMPs) by triggering activation of NF-κB, AP1, CREB, c/EBP, and IRF transcription factors. Induction of genes encoding enzymes, chemokines, cytokines, adhesion molecules, and regulators of the extracellular matrix promotes the recruitment and activation of leukocytes, which are critical for eliminating foreign particles and host debris. A subset of PRRs activates the protease caspase-1, which causes maturation of the cytokines IL1β and IL18. Cell adhesion molecules and chemokines facilitate leukocyte extravasation from the circulation to the affected site, the chemokines stimulating G-protein-coupled receptors (GPCRs). Binding initiates signals that regulate leukocyte motility and effector functions. Other triggers of inflammation include allergens, which form antibody complexes that stimulate Fc receptors on mast cells. Although the role of inflammation is to resolve infection and injury, increasing evidence indicates that chronic inflammation is a risk factor for cancer.

Serum cystatin C correlates negatively with viral load in treatment-naïve children with chronic hepatitis C

OBJECTIVES

Hepatitis C virus (HCV) infection is a serious health problem that causes chronic infection in up to 85% of cases. HCV nonstructural (NS) cysteine protease, NS2/3, is required for viral replication in vivo. Cystatin C is a naturally occurring cysteine protease inhibitor in human cells. We aimed to investigate the relation between serum levels of cystatin C and HCV viremia in treatment-naïve children with chronic hepatitis C.

METHODS

Serum cystatin C levels were measured in 27 children with chronic hepatitis C and determined their relation with liver functions, histopathological parameters, and hepatitis C viral load. Serum cystatin C was compared with that of 25 age- and sex-matched healthy controls.

RESULTS

Cystatin C was significantly higher in patients than in controls (1.4 ± 0.47 vs 0.99 ± 0.49; P = 0.006), and in those with low viremia than in those with moderate viremia (1.55 ± 0.41 vs 0.99 ± 0.43; P = 0.013). Cystatin C was not correlated with histopathological findings in liver biopsy (P > 0.05 for all). In addition, there was no significant difference of cystatin C levels in patients with normal versus those with elevated transaminases (P > 0.05). Of importance, cystatin C correlated negatively with viral load (P < 0.0001).

CONCLUSIONS

Cystatin C levels correlated negatively with HCV viremia. This finding may reflect an inhibitory effect of cystatin C on HCV replication through inhibiting its NS2/3 and tempting for further studies for cystatin C as a possible adjuvant therapy for HCV infection.

An orally available, small-molecule interferon inhibits viral replication

Most acute hepatitis C virus (HCV) infections become chronic and some progress to liver cirrhosis or hepatocellular carcinoma. Standard therapy involves an interferon (IFN)-α-based regimen, and efficacy of therapy has been significantly improved by the development of protease inhibitors. However, several issues remain concerning the injectable form and the side effects of IFN. Here, we report an orally available, small-molecule type I IFN receptor agonist that directly transduces the IFN signal cascade and stimulates antiviral gene expression. Like type I IFN, the small-molecule compound induces IFN-stimulated gene (ISG) expression for antiviral activity in vitro and in vivo in mice, and the ISG induction mechanism is attributed to a direct interaction between the compound and IFN-α receptor 2, a key molecule of IFN-signaling on the cell surface. Our study highlights the importance of an orally active IFN-like agent, both as a therapy for antiviral infections and as a potential IFN substitute.

Crystal structure of the HCV IRES central domain reveals strategy for start-codon positioning

Translation of hepatitis C viral proteins requires an internal ribosome entry site (IRES) located in the 5' untranslated region of the viral mRNA. The core domain of the hepatitis C virus (HCV) IRES contains a four-way helical junction that is integrated within a predicted pseudoknot. This domain is required for positioning the mRNA start codon correctly on the 40S ribosomal subunit during translation initiation. Here, we present the crystal structure of this RNA, revealing a complex double-pseudoknot fold that establishes the alignment of two helical elements on either side of the four-helix junction. The conformation of this core domain constrains the open reading frame's orientation for positioning on the 40S ribosomal subunit. This structure, representing the last major domain of HCV-like IRESs to be determined at near-atomic resolution, provides the basis for a comprehensive cryoelectron microscopy-guided model of the intact HCV IRES and its interaction with 40S ribosomal subunits.

Generation of a recombinant reporter hepatitis C virus useful for the analyses of virus entry, intra-cellular replication and virion production

The lack of a culture system that efficiently produces progeny virus has hampered hepatitis C virus (HCV) research. Recently, the discovery of a novel HCV isolate JFH1 and its chimeric derivative J6/JFH1 has led to the development of an efficient virus productive culture system. To construct an easy monitoring system for the viral life cycle of HCV, we generated bicistronic luciferase reporter virus genomes based on the JFH1 and J6/JFH1 isolates, respectively. Transfection of the J6/JFH1-based reporter genome to Huh7.5 cells produced significantly greater levels of progeny virus than transfection of the JFH1 genome. Furthermore, the expression of dominant-negative Vps4, a key molecule of the endosomal sorting complex required for transport machinery, inhibited the virus production of JFH1, but not that of J6/JFH1. These results may account for the different abilities to produce progeny virus between JFH1 and J6/JFH1. Using the J6/JFH1/Luc system, we showed that the two polyanions heparin and polyvinyl sulfate decreased the infectivity of J6/JFH1/Luc virus in a dose-dependent manner. We also analyzed the function of microRNA on HCV replication and found that miR-34b could affect the replication of HCV. The reporter virus generated in this study will be useful for investigating the nature of the HCV life cycle and for identification of HCV inhibitors.

Zebrafish as a potential model organism for drug test against hepatitis C virus

Screening and evaluating anti- hepatitis C virus (HCV) drugs in vivo is difficult worldwide, mainly because of the lack of suitable small animal models. We investigate whether zebrafish could be a model organism for HCV replication. To achieve NS5B-dependent replication an HCV sub-replicon was designed and created with two vectors, one with HCV ns5b and fluorescent rfp genes, and the other containing HCV's 5′UTR, core, 3′UTR and fluorescent gfp genes. The vectors containing sub-replicons were co-injected into zebrafish zygotes. The sub-replicon amplified in liver showing a significant expression of HCV core RNA and protein. The sub-replicon amplification caused no abnormality in development and growth of zebrafish larvae, but induced gene expression change similar to that in human hepatocytes. As the amplified core fluorescence in live zebrafish was detectable microscopically, it rendered us an advantage to select those with replicating sub-replicon for drug experiments. Ribavirin and oxymatrine, two known anti-HCV drugs, inhibited sub-replicon amplification in this model showing reduced levels of HCV core RNA and protein. Technically, this method had a good reproducibility and is easy to operate. Thus, zebrafish might be a model organism to host HCV, and this zebrafish/HCV (sub-replicon) system could be an animal model for anti-HCV drug screening and evaluation.

Optimized high-throughput screen for hepatitis C virus translation inhibitors

Hepatitis C virus (HCV) is a considerable global health problem for which new classes of therapeutics are needed. The authors developed a high-throughput assay to identify compounds that selectively block translation initiation from the HCV internal ribosome entry site (HCV IRES). Rabbit reticulocyte lysate conditions were optimized to faithfully report on authentic HCV IRES-dependent translation relative to a 5' capped mRNA control. The authors screened a library of ~430,000 small molecules for IRES inhibition, leading to ~1700 initial hits. After secondary counterscreening, the vast majority of hits proved to be luciferase and general translation inhibitors. Despite well-optimized in vitro translation conditions, in the end, the authors found no selective HCV IRES inhibitors but did discover a new scaffold of general translation inhibitor. The analysis of these molecules, as well we the finding that a large fraction of false positives resulted from off-target effects, highlights the challenges inherent in screens for RNA-specific inhibitors.

HIV/HCV co-infection: pathogenesis, clinical complications, treatment, and new therapeutic technologies

World-wide, hepatitis C virus (HCV) accounts for approximately 130 million chronic infections, with an overall 3% prevalence. Four to 5 million persons are co-infected with HIV. It is well established that HIV has a negative impact on the natural history of HCV, including a higher rate of viral persistence, increased viral load, and more rapid progression to fibrosis, end-stage liver disease, and death. Whether HCV has a negative impact on HIV disease progression continues to be debated. However, following the introduction of effective combination antiretroviral therapy, the survival of coinfected individuals has significantly improved and HCV-associated diseases have emerged as the most important co-morbidities. In this review, we summarize the newest studies regarding the pathogenesis of HIV/HCV coinfection, including effects of coinfection on HIV disease progression, HCV-associated liver disease, the immune system, kidney and cardiovascular disease, and neurologic status; and effectiveness of current anti-HIV and HCV therapies and proposed new treatment strategies.

Hepatocellular carcinoma xenograft supports HCV replication: A mouse model for evaluating antivirals

AIM: To develop a hepatocellular carcinoma (HCC) xenograft model for studying hepatitis C virus (HCV) replication in a mice, and antiviral treatment.

METHODS: We developed a stable S3-green fluorescence protein (GFP) cell line that replicated the GFP-tagged HCV sub-genomic RNA derived from a highly efficient JFH1 virus. S3-GFP replicon cell line was injected subcutaneously into γ-irradiated SCID mice. We showed that the S3-GFP replicon cell line formed human HCC xenografts in SCID mice. Cells were isolated from subcutaneous tumors and then serially passaged multiple times in SCID mice by culturing in growth medium supplemented with G-418. The mouse-adapted S3-GFP replicon cells were implanted subcutaneously and also into the liver of SCID mice via intrasplenic infusion to study the replication of HCV in the HCC xenografts. The tumor model was validated for antiviral testing after intraperitoneal injection of interferon-α (IFN-α).

RESULTS: A highly tumorigenic S3-GFP replicon cell line was developed that formed subcutaneous tumors within 2 wk and diffuse liver metastasis within 4 wk in SCID mice. Replication of HCV in the subcutaneous and liver tumors was confirmed by cell colony assay, detection of the viral RNA by ribonuclease protection assay and real-time quantitative reverse transcription polymerase chain reaction. High-level replication of HCV sub-genomic RNA in the tumor could be visualized by GFP expression using fluorescence microscopy. IFN-α cleared HCV RNA replication in the subcutaneous tumors within 2 wk and 4 wk in the liver tumor model.

CONCLUSION: A non-infectious mouse model allows us to study replication of HCV in subcutaneous and metastatic liver tumors. Clearance of HCV by IFN-α supports use of this model to test other anti-HCV drugs.

Partial splenic embolization facilitates the adherence to peginterferon in chronic hepatitis C with thrombocytopenia

OBJECTIVE

Platelet counts before starting the treatment affect the discontinuation and dose reduction of peginterferon in chronic hepatitis C. Thrombocytopenia leads to failure to achieve sustained virological response. This study was undertaken to evaluate the efficacy of partial splenic embolization (PSE) prior to starting peginterferon therapy combined with ribavirin in chronic hepatitis C patients showing thrombocytopenia.

PATIENTS AND METHODS

We compared the clinical features of 11 patients receiving PSE (PSE group) prior to starting the combined therapy with those of 13 patients not receiving PSE (non-PSE group). All of the patients showed platelet counts ≤12×10(4)/mm(3) and serum hepatitis C virus-RNA levels ≥100 KIU/mL at baseline. The end-point of PSE was a volume of splenic infarction over 75%. Peginterferon alpha-2b at a dose of 1.2 µg/kg was administered by subcutaneous injection once a week. The dose of ribavirin was weight adjusted.

RESULTS

PSE was successfully performed without serious adverse events. The period from PSE to starting the combined therapy was 14 (6-27) days. After PSE, platelet counts were significantly increased. In PSE group, platelet counts during the combined therapy were maintained above those at baseline. In non-PSE group, platelet counts at the 2nd week after the start of the combined therapy significantly decreased to less than those at baseline. Overall, 80% adherence to expected peginterferon dose was not achieved in 5 patients (45%) of PSE group and in 11 (85%) of non-PSE group (p=0.043).

CONCLUSION

Increased platelet counts after PSE facilitates the adherence to peginterferon therapy in chronic hepatitis C patients with thrombocytopenia.

Discovery of potent nucleotide-mimicking competitive inhibitors of hepatitis C virus NS3 helicase

Among the enzymes involved in the life cycle of HCV, the non-structural protein NS3, with its double function of protease and NTPase/helicase, is essential for the virus replication. Exploiting our previous knowledge in the development of nucleotide-mimicking NS3 helicase (NS3h) inhibitors endowed with key structural and electronic features necessary for an optimal ligand-enzyme interaction, we developed the tetrahydroacridinyl derivative 3a as the most potent NS3h competitive inhibitor reported to date (HCV NS3h K(i)=20 nM).

Distinct intracellular trafficking of hepatitis C virus in myeloid and plasmacytoid dendritic cells

Dendritic cells (DCs) are of pivotal importance for the initiation of immune responses to control and eliminate viral infections. The molecular mechanisms of hepatitis C virus (HCV) antigen uptake and processing by blood DCs are poorly defined. Here we show that human blood DC subsets acquire HCV independent of the classical HCV entry factors. Following HCV uptake, human plasmacytoid and myeloid DC subsets deliver HCV antigen into distinct endocytotic compartments, which are dedicated to presentation to CD4(+) or CD8(+) T cells. Our findings support a model of HCV antigen processing and presentation in which DC subsets fulfill distinct functions.

Virus-host interactions in hepatitis C virus infection: implications for molecular pathogenesis and antiviral strategies

With a global burden of 170 million chronically infected patients and a major cause of liver cirrhosis and hepatocellular carcinoma, hepatitis C virus (HCV) is a major public health challenge. Recent discoveries of viral and cellular factors mediating virus-host interactions have allowed scientists to uncover the key molecular mechanisms of viral infection and escape from innate and adaptive immune responses. These include the discovery of tight junction proteins as entry factors and microRNA-122, cyclophilins and lipoproteins as host factors for virus translation, replication and production. Furthermore, global genetic analyses have identified IL-28B as a genetic factor associated with the outcome of HCV infection. These discoveries markedly advance the understanding of the molecular pathogenesis of HCV infection and uncover novel targets for urgently needed antiviral strategies.

Thermal stability and inactivation of hepatitis C virus grown in cell culture

Background

Hepatitis C virus (HCV) is a blood-borne flavivirus that infects many millions of people worldwide. Relatively little is known, however, concerning the stability of HCV and reliable procedures for inactivating this virus.

Methods

In the current study, the thermostability of cell culture-derived HCV (HCVcc, JFH-1 strain) under different environmental temperatures (37°C, room temperature, and 4°C) and the ability of heat, UVC light irradiation, and aldehyde and detergent treatments to inactivate HCVcc were evaluated. The infectious titers of treated viral samples were determined by focus-forming unit (FFU) assay using an indirect immunofluorescence assay for HCV NS3 in hepatoma Huh7-25-CD81 cells highly permissive for HCVcc infection. MTT cytotoxicity assay was performed to determine the concentrations of aldehydes or detergents at which they were no longer cytotoxic.

Results

HCVcc in culture medium was found to survive 37°C and room temperature (RT, 25 ± 2°C) for 2 and 16 days, respectively, while the virus was relatively stable at 4°C without drastic loss of infectivity for at least 6 weeks. HCVcc in culture medium was sensitive to heat and could be inactivated in 8 and 4 min when incubated at 60°C and 65°C, respectively. However, at 56°C, 40 min were required to eliminate HCVcc infectivity. Addition of normal human serum to HCVcc did not significantly alter viral stability at RT or its susceptibility to heat. UVC light irradiation (wavelength = 253.7 nm) with an intensity of 450 μW/cm² efficiently inactivated HCVcc within 2 min. Exposures to formaldehyde, glutaraldehyde, ionic or nonionic detergents all destroyed HCVcc infectivity effectively, regardless of whether the treatments were conducted in the presence of cell culture medium or human serum.

Conclusions

The results provide quantitative evidence for the potential use of a variety of approaches for inactivating HCV. The ability of HCVcc to survive ambient temperatures warrants precautions in handling and disposing of objects and materials that may have been contaminated with HCV.

Impaired antiviral activity of interferon alpha against hepatitis C virus 2a in Huh-7 cells with a defective Jak-Stat pathway

Background

The sustained virological response to interferon-alpha (IFN-α) in individuals infected with hepatitis C virus (HCV) genotype 1 is only 50%, but is about 80% in patients infected with genotype 2-6 viruses. The molecular mechanisms explaining the differences in IFN-α responsiveness between HCV 1 and other genotypes have not been elucidated.

Results

Virus and host cellular factors contributing to IFN responsiveness were analyzed using a green fluorescence protein (GFP) based replication system of HCV 2a and Huh-7 cell clones that either possesses or lack a functional Jak-Stat pathway. The GFP gene was inserted into the C-terminal non-structural protein 5A of HCV 2a full-length and sub-genomic clones. Both HCV clones replicated to a high level in Huh-7 cells and could be visualized by either fluorescence microscopy or flow cytometric analysis. Huh-7 cells transfected with the GFP tagged HCV 2a genome produced infectious virus particles and the replication of fluorescence virus particles was demonstrated in naïve Huh-7.5 cells after infection. IFN-α effectively inhibited the replication of full-length as well as sub-genomic HCV 2a clones in Huh-7 cells with a functional Jak-Stat pathway. However, the antiviral effect of IFN-α against HCV 2a virus was not observed in Huh-7 cell clones with a defect in Jak-Stat signaling. HCV infection or replication did not alter IFN-α induced Stat phosphorylation or ISRE promoter-luciferase activity in both the sensitive and resistant Huh-7 cell clones.

Conclusions

The cellular Jak-Stat pathway is critical for a successful IFN-α antiviral response against HCV 2a. HCV infection or replication did not alter signaling by the Jak-Stat pathway. GFP labeled JFH1 2a replicon based stable cell lines with IFN sensitive and IFN resistant phenotypes can be used to develop new strategies to overcome IFN-resistance against hepatitis C.

Rational design of immunostimulatory siRNAs

Short-interfering RNAs (siRNAs) have engendered much enthusiasm for their ability to silence the expression of specific genes. However, it is now well established that siRNAs, depending on their sequence, can be variably sensed by the innate immune system through recruitment of toll-like receptors 7 and 8 (TLR7/8). Here, we aimed to identify sequence-based modifications allowing for the design of bifunctional siRNAs with both proinflammatory and specific silencing activities, and with potentially increased therapeutic benefits. We found that the introduction of a micro-RNA (miRNA)-like nonpairing uridine-bulge in the passenger strand robustly increased immunostimulatory activity on human immune cells. This sequence modification had no effect on the silencing efficiency of the siRNA. Increased immunostimulation with the uridine-bulge design was specific to human cells, and conserved silencing efficiency required a Dicer-substrate scaffold. The increased cytokine production with the uridine-bulge design resulted in enhanced protection against Semliki Forest virus (SFV) infection, in viral assays. Thus, we characterize a design scaffold applicable to any given siRNA sequence, that results in increased innate immune activation without affecting gene silencing. Our data suggest that this sequence modification coupled with structural modification differentially recruits human TLR8 over TLR7, and could have potential application in antiviral therapies.

HCV drug discovery aimed at viral eradication

Hepatitis C virus (HCV) causes significant morbidity and mortality worldwide with nearly 3% of the world population infected by this virus. Fortunately, this virus does not establish latency, and hence it may be possible to eradicate it. HCV is strongly associated with liver cirrhosis and hepatocellular carcinoma and is currently treated with pegylated interferon-alpha (peg-IFN-alpha) and ribavirin. Unfortunately, these limited treatment options often produce significant side effects, and currently, complete eradication of virus with combined drug modalities has not yet been achieved for the majority of chronically HCV-infected individuals. Restricted treatment options, lack of a universal cure for HCV and the link between chronic infection, liver cirrhosis and hepatocellular carcinoma necessitate design of novel drugs and treatment options. Understanding the relationship between the immune response, viral clearance and inhibition of viral replication with pharmacology-based design can ultimately allow for complete eradication of HCV. This review focuses upon significant novel preclinical and clinical specifically targeted antiviral therapy (STAT-C) drugs under development, highlights their mechanism of action, and discusses their impact on systemic viral loads and permanent clearance of infection.

Laparoscopic splenectomy may be a superior supportive intervention for cirrhotic patients with hypersplenism

BACKGROUND AND AIMS

To evaluate and compare laparoscopic splenectomy and partial splenic embolization as supportive intervention for cirrhotic patients with hypersplenism to overcome peripheral cytopenia before the initiation of and during interferon therapy or anticancer therapy for hepatocellular carcinoma.

METHODS

Between December 2000 and April 2008, 43 Japanese cirrhotic patients with hypersplenism underwent either laparoscopic splenectomy or partial splenic embolization as a supportive intervention to facilitate the initiation and completion of either interferon therapy or anticancer therapy for hepatocellular carcinoma. We reviewed the peri- and post-intervention outcomes and details of the subsequent planned main therapies. For interferon therapy, the rate of completion, the rate of treatment cessation and virological responses were evaluated. Anti-cancer therapies for hepatocellular carcinoma included liver resection, ablation therapy, intra-arterial chemotherapy, and transarterial chemoembolization.

RESULTS

All patients tolerated the operations well with no significant complications. The platelet count was significantly higher in the laparoscopic splenectomy group than in the partial splenic embolization group at 1 and 2 weeks after the intervention. Interferon therapy was stopped in two patients in the partial splenic embolization group due to recurrent thrombocytopenia whereas all patients in the laparoscopic splenectomy group completed interferon therapy. The planned anticancer therapies were performed in all patients, and were completed in all patients without any problems or major complications.

CONCLUSION

Laparoscopic splenectomy may be superior to partial splenic embolization as a supportive intervention for cirrhotic patients with hypersplenism. Future prospective, randomized controlled patient studies are required to confirm these findings.

The heme oxygenase 1 product biliverdin interferes with hepatitis C virus replication by increasing antiviral interferon response

The anti-inflammatory and antiapoptotic heme degrading enzyme heme oxygenase-1 (HO-1) has been shown recently to interfere with replication of hepatitis C virus (HCV). We investigated the effect of HO-1 products carbon monoxide (CO), iron and biliverdin on HCV replication using the replicon cell lines Huh-5-15 and LucUbiNeo-ET, stably expressing HCV proteins NS3 through NS5B. Incubation of these cell lines in the presence of the CO donor methylene chloride transiently reduced HCV replication, whereas an increase of iron in cell culture by administration of FeCl(3) or iron-saturated lactoferrin did not interfere with HCV replication. Likewise, depletion of iron by deferoxamine during induction of HO-1 by cobalt-protoporphyrin IX did not restore HCV replication. The most prominent effect was observed after incubation of replicon cell lines in the presence of biliverdin. Biliverdin seems to interfere with HCV replication-mediated oxidative stress by inducing expression of antiviral interferons, such as interferon alpha2 and alpha17.

CONCLUSION

The antioxidant biliverdin reduces HCV replication in vitro by triggering the antiviral interferon response and might improve HCV therapy in the future.

Role of scavenger receptor class B type I in hepatitis C virus entry: kinetics and molecular determinants

Scavenger receptor class B type I (SR-BI) is an essential receptor for hepatitis C virus (HCV) and a cell surface high-density-lipoprotein (HDL) receptor. The mechanism of SR-BI-mediated HCV entry, however, is not clearly understood, and the specific protein determinants required for the recognition of the virus envelope are not known. HCV infection is strictly linked to lipoprotein metabolism, and HCV virions may initially interact with SR-BI through associated lipoproteins before subsequent direct interactions of the viral glycoproteins with SR-BI occur. The kinetics of inhibition of cell culture-derived HCV (HCVcc) infection with an anti-SR-BI monoclonal antibody imply that the recognition of SR-BI by HCV is an early event of the infection process. Swapping and single-substitution mutants between mouse and human SR-BI sequences showed reduced binding to the recombinant soluble E2 (sE2) envelope glycoprotein, thus suggesting that the SR-BI interaction with the HCV envelope is likely to involve species-specific protein elements. Most importantly, SR-BI mutants defective for sE2 binding, although retaining wild-type activity for receptor oligomerization and binding to the physiological ligand HDL, were impaired in their ability to fully restore HCVcc infectivity when transduced into an SR-BI-knocked-down Huh-7.5 cell line. These findings suggest a specific and direct role for the identified residues in binding HCV and mediating virus entry. Moreover, the observation that different regions of SR-BI are involved in HCV and HDL binding supports the hypothesis that new therapeutic strategies aimed at interfering with virus/SR-BI recognition are feasible.

Dengue

INTRODUCTION

Dengue is a vector-borne viral infection that endangers an estimated 2.5 billion people. Disease caused by dengue ranges from a relatively minor febrile illness to a life-threatening condition characterized by extensive capillary leak. A greater understanding of dengue has the potential to improve both the clinical management of individual cases and the control of the disease.

SOURCES OF DATA

We searched the available literature using PubMed, Embase and Web of Science for relevant articles and abstracts.

AREAS OF AGREEMENT

Addressing our gaps in the understanding of disease pathogenesis and improving our knowledge of dengue virus biology are necessary in order to develop tools to effectively control, diagnose and treat the disease.

AREAS OF CONTROVERSY

The pathogenesis of dengue is multifactorial and depends on both host and virus factors. A more integrated understanding of disease pathogenesis is necessary.

AREAS TIMELY FOR DEVELOPING RESEARCH

There are many questions related to disease pathogenesis, development of diagnostics, drug and vaccine development and individual case management that need addressing if the disease is to be successfully tackled.

Clinical relevance of genetic heterogeneity in HCV

Infection by HCV affects an estimated 170 million people worldwide and it represents one of the major causes of liver transplantation and a heavy burden to healthcare systems. As with many other RNA viruses, HCV is characterized by very high levels of genetic variation, which have been associated to differences in disease progression and efficiency of antiviral treatment. Studies show many contradictory results and little consensus on such associations. Nevertheless, some general guidelines translating research results to clinical practice have been postulated. Here, we review the main research results obtained on HCV variation so far and explore the reasons for their lack of congruence under a population genetics framework. Understanding the factors responsible for the variable dynamics of HCV diversity in human populations and variation within infected individuals is even more necessary in face of the soon-to-arrive new HCV therapies.

Hepatitis C virus (HCV) infection may elicit neutralizing antibodies targeting epitopes conserved in all viral genotypes

Anti-hepatitis C virus (HCV) cross-neutralizing human monoclonal antibodies, directed against conserved epitopes on surface E2 glycoprotein, are central tools for understanding virus-host interplay, and for planning strategies for prevention and treatment of this infection. Recently, we developed a research aimed at identifying these antibody specificities. The characteristics of one of these antibodies (Fab e20) were addressed in this study. Firstly, using immunofluorescence and FACS analysis of cells expressing envelope HCV glycoproteins, Fab e20 was able to recognize all HCV genotypes. Secondly, competition assays with a panel of mouse and rat monoclonals, and alanine scanning mutagenesis analyses located the e20 epitope within the CD81 binding site, documenting that three highly conserved HCV/E2 residues (W529, G530 and D535) are critical for e20 binding. Finally, a strong neutralizing activity against HCV pseudoparticles (HCVpp) incorporating envelope glycoproteins of genotypes 1a, 1b, 2a, 2b and 4, and against the cell culture-grown (HCVcc) JFH1 strain, was observed. The data highlight that neutralizing antibodies against HCV epitopes present in all HCV genotypes are elicited during natural infection. Their availability may open new avenues to the understanding of HCV persistence and to the development of strategies for the immune control of this infection.