Interferon-based therapy of hepatitis C

Influences of chronic copper exposure on intestinal histology, antioxidative and immune status, and transcriptomic response in freshwater grouper (Acrossocheilus fasciatus)

Copper (Cu) contamination is commonly found in both natural water environments and fish farms, and it can cause severe damage to different fish organs, but Cu-induced intestinal damage has been rarely studied. This study subjected three groups of freshwater grouper (Acrossocheilus fasciatus) (initial weight: 1.56 ± 0.10 g) to 0 mg/L, 0.01 mg/L, and 0.04 mg/L Cu2+ for 30 days, named Con, Cu0.01, and Cu0.04 groups, respectively. The histological observation indicated that the Cu0.04 group caused a significant decrease in villus length, lamina propria width, and muscular thickness compared to the Con group (P < 0.05). Additionally, the Cu0.04 group significantly increased intestinal superoxide dismutase (SOD), glutathione peroxidase (GPx), lysozyme (LZM) activities, as well as malondialdehyde (MDA) content than the Con group (P < 0.05). Meanwhile, the Cu0.01 and Cu0.04 groups showed significantly increased immunoglobulin M (IgM), complement 3 (C3), and glutathione (GSH) contents than the Con group (P < 0.05). Transcriptomic analysis revealed a total of 101 differentially expressed genes (DEGs), including 47 up-regulated and 54 down-regulated DEGs, were identified between the Cu0.04 and Con groups. Notably, the DEGs were mainly related to intestinal structure construction, immune functions, apoptosis, and resistance to DNA damage and pathogen infection. The findings suggest that chronic Cu exposure caused intestinal histological alterations, activated the antioxidative and immune systems, and induced systematic adaptation to cope with the physical barrier injury, DNA damage, and potential pathogen growth.

Management of ocular surface squamous neoplasia: Bowman Club Lecture 2021

The gold-standard treatment for ocular surface squamous neoplasia (OSSN) has traditionally been surgical excision with wide margins and a no-touch technique. However, surgery may be associated with several unfavourable sequelae, as well as significant recurrence rates if margins are positive. In recent years, topical chemotherapy with 5-fluorouracil, interferon α-2b and mitomycin C have emerged as valuable agents capable of effectively treating OSSN with varying adverse effects. These medical treatment options usually present additional costs to the patient but can allow patients to avoid surgery with fewer long-term effects. Anterior segment high-resolution optical coherence tomography is an excellent tool for diagnosing and monitoring OSSN and can be a useful aid for both surgical and medical treatments of OSSN.

Identification of an IRF10 gene in common carp (Cyprinus carpio L.) and analysis of its function in the antiviral and antibacterial immune response

Background

Interferon (IFN) regulatory factors (IRFs), as transcriptional regulatory factors, play important roles in regulating the expression of type I IFN and IFN- stimulated genes (ISGs) in innate immune responses. In addition, they participate in cell growth and development and regulate oncogenesis.

Results

In the present study, the cDNA sequence of IRF10 in common carp (Cyprinus carpio L.) was characterized (abbreviation, CcIRF10). The predicted protein sequence of CcIRF10 shared 52.7–89.2% identity with other teleost IRF10s and contained a DNA-binding domain (DBD), a nuclear localization signal (NLS) and an IRF-associated domain (IAD). Phylogenetic analysis showed that CcIRF10 had the closest relationship with IRF10 of Ctenopharyngodon idella. CcIRF10 transcripts were detectable in all examined tissues, with the highest expression in the gonad and the lowest expression in the head kidney. CcIRF10 expression was upregulated in the spleen, head kidney, foregut and hindgut upon polyinosinic:polycytidylic acid (poly I:C) and Aeromonas hydrophila stimulation and induced by poly I:C, lipopolysaccharide (LPS) and peptidoglycan (PGN) in peripheral blood leucocytes (PBLs) and head kidney leukocytes (HKLs) of C. carpio. In addition, overexpression of CcIRF10 was able to decrease the expression of the IFN and IFN-stimulated genes PKR and ISG15.

Conclusions

These results indicate that CcIRF10 participates in antiviral and antibacterial immunity and negatively regulates the IFN response, which provides new insights into the IFN system of C. carpio.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-020-02674-z.

Prediction of recurrence following hepatectomy in patients with hepatitis C virus infection-related hepatocellular carcinoma who achieved a sustained virological response

AIM

The risk of hepatitis C virus infection-related hepatocellular carcinoma (HCC) is lower, with a better prognosis, in patients who achieve a sustained virological response (SVR) than in those who do not. We aimed to identify risk factors of post-hepatectomy HCC recurrence in patients who achieved a SVR.

METHODS

This retrospective study included 349 HCC patients who underwent an initial radical hepatectomy at our institution between January 2005 and December 2014. Sixty-eight patients had achieved a SVR (the SVR group) and 281 patients had not (the non-SVR group). Clinical characteristics and long-term outcomes were compared between the two groups. Univariate and multivariate analyses identified variables associated with recurrence-free survival in the SVR group.

RESULTS

Post-hepatectomy overall and recurrence-free survival rates were significantly higher in the SVR group than the non-SVR group (P < 0.01 and <0.05, respectively). Univariate analysis of post-hepatectomy recurrence-free survival in the SVR group revealed multiple significant factors: aspartate aminotransferase, 25 IU/L or more (P = 0.01); indocyanine green retention rate at 15 min, 20.0% or less (P < 0.05); hepatic vascular invasion (P < 0.05); and an interval of months or less between achieving a SVR and hepatectomy (P < 0.01). Multivariate analysis confirmed an interval of 30 months or less between achieving a SVR and hepatectomy as an independent prognostic factor of recurrence-free survival (hazard ratio, 2.30; 95.0% confidence interval, 1.04-5.13; P < 0.05).

CONCLUSION

The interval between achieving a SVR and hepatectomy is an important predictor of recurrence in hepatitis C virus infection-related HCC patients who achieved a SVR.

IFN-α-based treatment of patients with chronic HCV show increased levels of cells with myeloid-derived suppressor cell phenotype and of IDO and NOS

INTRODUCTION

Hepatitis C virus (HCV) infection causes chronic hepatitis, which is often associated with suppressed anti-HCV immune responses. We have recently reported accumulation of myeloid-derived suppressor cells (MDSCs) and suppressed immunity in cancer patients.

AIM

The main aim of this study was to determine whether chronic HCV patients harbor high of MDSCs in general and in nonresponders to IFN-based therapy in particular as well as to analyze the immune suppressive molecules.

METHODS

Peripheral blood samples withdrawn from 154 patients with chronic HCV infection and were categorized into responders and nonresponders based on viral titer upon IFN-α treatment.

RESULTS

The relative and absolute numbers of MDSCs defined as Lin^-/HLA-DR^-/CD33⁺/CD11b⁺ increased in all HCV patients, where they were higher in nonresponders than in responders. Additionally, the levels of MDSCs after 4-6 months of treatment in responders were lower than during the course of treatment. The responders also showed higher levels of IL-2 coincided with increased numbers of dendritic cells (DCs), CD4⁺ and CD8⁺ T cells. The levels of total NOS and IDO were also higher in nonresponders as compared to responders and healthy controls, while the expression levels of CD3ζ was lower in responders as compared to nonresponders and healthy volunteers.

CONCLUSION

Chronic HCV patients harbor high numbers of MDSCs, which are higher in nonresponders than in responders. The higher numbers of MDSCs associated with increases in the suppressing factors.

Evaluation of preclinical antimalarial drugs, which can overcome direct-acting antivirals-resistant hepatitis C viruses, using the viral reporter assay systems

Persistent hepatitis C virus (HCV) infection causes chronic liver diseases and is a major global health problem. Recently developed treatments with direct-acting antivirals (DAAs) have largely improved the sustained virologic response rate of patients with chronic hepatitis C. However, this approach is still hindered by its great expense and the problem of drug resistance. Using our cell-based HCV assay systems, we reported that the preclinical antimalarial drugs N-89 and N-251 exhibited potent anti-HCV activities. In this study we used our assay systems to evaluate the anti-HCV activities of six kinds of DAAs individually or in combination with N-89 or N-251. The results showed that the DAAs had potent anti-HCV activities and N-89 or N-251 contributed additive or synergistic effect. Using DAA-resistant HCV-RNA-replicating cells, which were prepared by continuous treatment with each DAA, we demonstrated that N-89 and N-251 could overcome all of the DAA-resistant HCVs. These preclinical drugs would have been potential as components of a therapeutic regimen that also included combinations of various DAAs. In addition, sequence analysis of the NS3-NS5B regions of the DAA-resistant HCV genomes newly found several amino acid (aa) substitutions that were suggested to contribute to DAA-resistance in addition to the aa substitutions already known to cause DAA-resistance. Among these new aa substitutions, we found that two substitutions in the NS3 region (D79G and S174Y) contributed to simeprevir- and/or asunaprevir-resistance.

von Willebrand factor antigen (vWF-Ag): A non-invasive predictor of treatment response and serious adverse events in HCV patients with interferon triple therapy

BACKGROUND

Treatment of chronic hepatitis C virus (HCV) infection was revolutionized within the last years. Interferon free antiviral regimens are not accessible without limitations. Combination of peginterferon/ribavirin with first generation direct acting antivirals is less effective and associated with serious adverse events.

AIM

We have shown that vWF-Ag is associated with portal hypertension and treatment response to PEG/RBV and we evaluated if vWF-Ag is a predictive marker for treatment response and safety in patients with triple therapy.

METHODS

222 HCV-GT 1 patients and DAA based triple therapy were included in this retrospective, multicenter study.

RESULTS

Median vWF-Ag levels were 167.0% [IQR: 124.0-210.0%]. Significantly higher levels were seen in patients without SVR; median 190% [IQR: 146.0-259.5%] versus SVR: 142.5% [IQR: 114.3-196.8%], p<0.001. Furthermore levels of vWF-Ag were identified as independent predictor of non SVR; (OR: 1.009; 95%CI: 1.016-1.3, p=0.005). In patients with cirrhosis elevated vWF-Ag levels were associated with increased incidence of SAEs (OR: 1.016; 95%CI: 1.004-1.028; p=0.007). Best cut off for prediction of SAEs was vWF-Ag>281.5% with a sensitivity of 78% and a specificity of 90%.

CONCLUSION

Baseline vWF-Ag levels predict outcome of DAA based treatment in HCV-1 patients and identify patients with a risk of SAEs. Therefore vWF-Ag may be an additional marker for selecting patients for interferon free therapeutic regimens.

Development of a high yield expression and purification system for Domain I of Beta-2-glycoprotein I for the treatment of APS

BACKGROUND

In this paper we describe a novel method to achieve high yield bacterial expression of a small protein domain with considerable therapeutic potential; Domain I of Beta-2-glycoprotein I (β2GPI). β2GPI is intrinsic to the pathological progression of the Antiphospholipid Syndrome (APS). Patients develop autoantibodies targeting an epitope located on the N-terminal Domain I of β2GPI rendering this domain of interest as a possible therapeutic.

RESULTS

This new method of production of Domain I of β2GPI has increased the production yield by ~20 fold compared to previous methods in E.coli. This largely scalable, partially automated method produces 50-75 mg of pure, folded, active Domain I of β2GPI per litre of expression media.

CONCLUSION

The application of this method may enable production of Domain I on sufficient scale to allow its use as a therapeutic.

Establishment of hepatitis C virus RNA-replicating cell lines possessing ribavirin-resistant phenotype

BACKGROUND

Ribavirin (RBV) is a potential partner of interferon-based therapy and recently approved therapy using direct acting antivirals for patients with chronic hepatitis C. However, the precise mechanisms underlying RBV action against hepatitis C virus (HCV) replication are not yet understood. To clarify this point, we attempted to develop RBV-resistant cells from RBV-sensitive HCV RNA-replicating cells.

METHODOLOGY/PRINCIPAL FINDINGS

By repetitive RBV (100 μM) treatment (10 weeks) of 3.5-year-cultured OL8 cells, in which genome-length HCV RNA (O strain of genotype 1b) efficiently replicates, dozens of colonies that survived RBV treatment were obtained. These colonies were mixed together and further treated with high doses of RBV (up to 200 μM). By such RBV treatment, we successfully established 12 RBV-survived genome-length HCV RNA-replicating cell lines. Among them, three representative cell lines were characterized. HCV RNA replication in these cells resisted RBV significantly more than that in the parental OL8 cells. Genetic analysis of HCV found several common and conserved amino acid substitutions in HCV proteins among the three RBV-resistant cell species. Furthermore, using cDNA microarray and quantitative RT-PCR analyses, we identified 5 host genes whose expression levels were commonly altered by more than four-fold among these RBV-resistant cells compared with the parental cells. Moreover, to determine whether viral or host factor contributes to RBV resistance, we developed newly HCV RNA-replicating cells by introducing total RNAs isolated from RBV-sensitive parental cells or RBV-resistant cells into the HCV RNA-cured-parental or -RBV-resistant cells using an electroporation method, and evaluated the degrees of RBV resistance of these developed cells. Consequently, we found that RBV-resistant phenotype was conferred mainly by host factor and partially by viral factor.

CONCLUSIONS/SIGNIFICANCE

These newly established HCV RNA-replicating cell lines should become useful tools for further understanding the anti-HCV mechanisms of RBV.

Molecular docking investigation of the binding interactions of macrocyclic inhibitors with HCV NS3 protease and its mutants (R155K, D168A and A156V)

Hepatitis C Virus (HCV) non-structural protein 3 (NS3) protease drug resistance poses serious challenges on the design of an effective treatment. Substrate Envelope Hypothesis, "the substrates of HCV NS3/4A protease have a consensus volume inside the active site called substrate envelope" is used to design potent and specific drugs to overcome this problem. Using molecular docking, we studied the binding interaction of the different inhibitors and protein and evaluated the effect of three different mutations (R155K, D168A and A156V) on the binding of inhibitors. P2-P4 macrocycles of 5A/5B and modified 5A/5B hexapeptide sequences have the best scores against the wild-type protein -204.506 and -206.823 kcal/mole, respectively. Also, charged P2-P4 macrocycles of 3/4A and 4A/4B hexapeptide sequences have low scores with the wild-type protein -200.467 and -203.186 kcal/mole, respectively. R155K mutation greatly affects the conformation of the compounds inside the active site. It inverts its orientations, and this is because the large and free side chain of K155 which restricts the conformation of the large P2-P4 macrocycle. The conformation of charged P2-P4 macrocycle of 3/4A hexapeptide sequence in wild-type, A156V and D168A proteins is nearly equal; while that of charged P2-P4 macrocycle of 4A/4B hexapeptide sequence is different. Nevertheless, these compounds have a slight increase of Van der Waals volume compared to that of substrates, they are potent against mutations and have good scores. Therefore, the suggested drugs can be used as an effective treatment solving HCV NS3/4A protease drug resistance problem.

Distribution pattern of hepatitis C virus genotypes and correlation with viral load and risk factors in chronic positive patients

OBJECTIVE

Hepatitis C virus (HCV) has emerged as a leading cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma worldwide. The purpose of this study was to describe the distribution pattern of HCV genotypes in chronic hepatitis patients in the Campania region of southern Italy and estimate their association with risk factors and viral load.

MATERIALS AND METHODS

404 consecutive HCV ribonucleic acid-positive patients were included in the study. HCV genotyping was carried out by the HCV line probe assay test and viral load estimation by the TaqMan real-time PCR system.

RESULTS

The predominant genotype was 1 (63.6%), followed by genotype 2 (29.4%), 3 (6.2%) and 4 (0.8%). Subtype 1b was more frequent in females than in males. Conversely, genotype 3 was more frequent in males. No significant difference was observed in age distribution of HCV genotypes. Surgery and dental therapy were the most frequent risk factors for genotype 1 and intravenous drug abuse and tattooing for genotype 3. Patients with genotype 1 more frequently showed high HCV viral load when compared to those with genotypes 2 and 3.

CONCLUSION

The present study revealed that HCV genotypes 1 and 2 accounted for over 95% of all HCV infections in the Campania region, and genotype 1 was more frequently associated with a higher viral load when compared to genotypes 2 and 3.

Discovery of daclatasvir, a pan-genotypic hepatitis C virus NS5A replication complex inhibitor with potent clinical effect

The discovery and development of the first-in-class hepatitis C virus (HCV) NS5A replication complex inhibitor daclatasvir (6) provides a compelling example of the power of phenotypic screening to identify leads engaging novel targets in mechanistically unique ways. HCV NS5A replication complex inhibitors are pan-genotypic in spectrum, and this mechanistic class provides the most potent HCV inhibitors in vitro that have been described to date. Clinical trials with 6 demonstrated a potent effect on reducing plasma viral load and, in combination with mechanistically orthogonal HCV inhibitors, established the ability to cure even the most difficult infections without the need for immune stimulation. In this Drug Annotation, we describe the discovery of the original high-throughput screening lead 7 and the chemical conundrum and challenges resolved in optimizing to 6 as a clinical candidate and finally we summarize the results of select clinical studies.

Expression of soluble and active interferon consensus in SUMO fusion expression system in E. coli

Protein production can be improved if methods for soluble protein expression are developed. Interferon consensus (IFN-con) is used to treat hepatitis C. IFN-con has superior activity compared to other clinically used interferon α subtypes. However IFN-con is a challenging protein to produce in a soluble form using an Escherichia coli expression system. Here we describe the expression of soluble and active recombinant IFN-con in E. coli. The IFN-con gene sequence was optimised for expression in E. coli, which was then cloned into the Champion™ pET SUMO expression vector downstream of the SUMO fusion protein and under strong T7lac promoter. The SUMO-IFN-con fusion protein was efficiently expressed using the SHuffle™ E. coli strain and existed in soluble form as 86-88% of the total IFN-con. After removal of the SUMO fusion partner, approximately 50mg of recombinant IFN-con of at least 98% purity (by RP-HPLC) was obtained from a 1L fermentation culture. Using an A549/EMCV antiviral assay, the specific activity of the recombinant IFN-con was determined to be 960×10(6) IU/mg as calculated to NIBSC standard for IFN-con (3×10(5)pfu/mL virus titre). Comparison of the antiviral activity of the produced IFN-con to IFN α-2a showed that IFN-con displays 2.8 times greater activity, which is in good agreement with what has been reported in the literature for pure protein. IFN-con expression in a soluble form from E. coli allowed us to use a simple, two-step purification process to yield highly pure and active IFN-con which is more efficient than obtaining IFN-con from inclusion bodies.

Recognition of 2',5'-linked oligoadenylates by human ribonuclease L: molecular dynamics study

The capability of current MD simulations to be used as a tool in rational design of agonists of medically interesting enzyme RNase L was tested. Dimerization and enzymatic activity of RNase L is stimulated by 2',5'-linked oligoadenylates (pA₂₅A₂₅A; 2-5A). First, it was necessary to ensure that a complex of monomeric human RNase L and 25A was stable in MD simulations. It turned out that Glu131 had to be protonated. The non-protonated Glu131 caused dissociation of 2-5A from RNase L. Because of the atypical 2'-5' internucleotide linkages and a specific spatial arrangement of the 25A trimer, when a single molecule carries all possible conformers of the glycosidic torsion angle, several versions of the AMBER force field were tested. One that best maintained functionally important interactions of 25A and RNase L was selected for subsequent MD simulations. Furthermore, we wonder whether powerful GPUs are able to produce MD trajectories long enough to convincingly demonstrate effects of subtle perturbations of interactions between 25A and RNase L. Detrimental impacts of various point mutations of RNase L (R155A, F126A, W60A, K89A) on 2-5A binding were observed on a time scale of 200 ns. Finally, 2-5A analogues with a bridged 3'--O,4'--C-alkylene linkage (B) introduced into the adenosine units (A) were used to assess ability of MD simulations to distinguish on the time scale of hundreds of nanoseconds between agonists of RNase L (pA₂₅A₂₅B, pB₂₅A₂₅A, pB₂₅A₂₅B) and inactive analogs (pA₂₅B₂₅A, pA₂₅B₂₅B, pB₂₅B₂₅A, pB₂₅B₂₅B). Agonists were potently bound to RNase L during 200 ns MD runs. For inactive 2-5A analogs, by contrast, significant disruptions of their interactions with RNase L already within 100 ns MD runs were found.

New preclinical antimalarial drugs potently inhibit hepatitis C virus genotype 1b RNA replication

BACKGROUND

Persistent hepatitis C virus (HCV) infection causes chronic liver diseases and is a global health problem. Although new triple therapy (pegylated-interferon, ribavirin, and telaprevir/boceprevir) has recently been started and is expected to achieve a sustained virologic response of more than 70% in HCV genotype 1 patients, there are several problems to be resolved, including skin rash/ageusia and advanced anemia. Thus a new type of anti-HCV drug is still needed.

METHODOLOGY/PRINCIPAL FINDINGS

Recently developed HCV drug assay systems using HCV-RNA-replicating cells (e.g., HuH-7-derived OR6 and Li23-derived ORL8) were used to evaluate the anti-HCV activity of drug candidates. During the course of the evaluation of anti-HCV candidates, we unexpectedly found that two preclinical antimalarial drugs (N-89 and its derivative N-251) showed potent anti-HCV activities at tens of nanomolar concentrations irrespective of the cell lines and HCV strains of genotype 1b. We confirmed that replication of authentic HCV-RNA was inhibited by these drugs. Interestingly, however, this anti-HCV activity did not work for JFH-1 strain of genotype 2a. We demonstrated that HCV-RNA-replicating cells were cured by treatment with only N-89. A comparative time course assay using N-89 and interferon-α demonstrated that N-89-treated ORL8 cells had more rapid anti-HCV kinetics than did interferon-α-treated cells. This anti-HCV activity was largely canceled by vitamin E. In combination with interferon-α and/or ribavirin, N-89 or N-251 exhibited a synergistic inhibitory effect.

CONCLUSIONS/SIGNIFICANCE

We found that the preclinical antimalarial drugs N-89 and N-251 exhibited very fast and potent anti-HCV activities using cell-based HCV-RNA-replication assay systems. N-89 and N-251 may be useful as a new type of anti-HCV reagents when used singly or in combination with interferon and/or ribavirin.

Extinction of hepatitis C virus by ribavirin in hepatoma cells involves lethal mutagenesis

Lethal mutagenesis, or virus extinction produced by enhanced mutation rates, is under investigation as an antiviral strategy that aims at counteracting the adaptive capacity of viral quasispecies, and avoiding selection of antiviral-escape mutants. To explore lethal mutagenesis of hepatitis C virus (HCV), it is important to establish whether ribavirin, the purine nucleoside analogue used in anti-HCV therapy, acts as a mutagenic agent during virus replication in cell culture. Here we report the effect of ribavirin during serial passages of HCV in human hepatoma Huh-7.5 cells, regarding viral progeny production and complexity of mutant spectra. Ribavirin produced an increase of mutant spectrum complexity and of the transition types associated with ribavirin mutagenesis, resulting in HCV extinction. Ribavirin-mediated depletion of intracellular GTP was not the major contributory factor to mutagenesis since mycophenolic acid evoked a similar decrease in GTP without an increase in mutant spectrum complexity. The intracellular concentration of the other nucleoside-triphosphates was elevated as a result of ribavirin treatment. Mycophenolic acid extinguished HCV without an intervening mutagenic activity. Ribavirin-mediated, but not mycophenolic acid-mediated, extinction of HCV occurred via a decrease of specific infectivity, a feature typical of lethal mutagenesis. We discuss some possibilities to explain disparate results on ribavirin mutagenesis of HCV.

Role of different regions of the hepatitis C virus genome in the therapeutic response to interferon-based treatment

Hepatitis C virus (HCV) is considered a significant risk factor in HCV-induced liver diseases and development of hepatocellular carcinoma (HCC). Nucleotide substitutions in the viral genome result in its diversification into quasispecies, subtypes and distinct genotypes. Different genotypes vary in their infectivity and immune response due to these nucleotide/amino acid variations. The current combination treatment for HCV infection is pegylated interferon α (PEG-IFN-α) with ribavirin, with a highly variable response rate mainly depending upon the HCV genotype. Genotypes 2 and 3 are found to respond better than genotypes 1 and 4, which are more resistant to IFN-based therapies. Different studies have been conducted worldwide to explore the basis of this difference in therapy response, which identified some putative regions in the HCV genome, especially in Core and NS5a, and to some extent in the E2 region, containing specific sequences in different genotypes that act differently with respect to the IFN response. In the review, we try to summarize the role of HCV proteins and their nucleotide sequences in association with treatment outcome in IFN-based therapy.

Molecular modeling comparison of the performance of NS5b polymerase inhibitor (PSI-7977) on prevalent HCV genotypes

The current available treatment for hepatitis C virus (HCV)-the causative of liver cirrhosis and development of liver cancer-is a dual therapy using modified interferon and ribavirin. While this regimen increases the sustained viral response rate up to 40-80 % in different genotypes, unfortunately, it is poorly tolerated by patients. PSI-7977, a prodrug for PSI-7409, is a Non-Structural 5b (NS5b) polymerase nucleoside inhibitor that is currently in phase III clinical trials. The activated PSI-7977 is a direct acting antiviral (DAA) drug that acts on NS5b polymerase of HCV through a coordination bond with the two Mg(+2) present at the GDD active site motif. The present work utilizes a molecular modeling approach for studying the interaction between the activated PSI-7977 and the 12 amino acids constituting a 5 Å region surrounding the GDD active triad motif for HCV genotypes 1a, 2b, 3b and 4a. The analysis of the interaction parameters suggests that PSI-7977 is probably a better DAA drug for HCV genotypes 1a and 3b rather than genotypes 2b and 4a.

Development of a multiplex phenotypic cell-based high throughput screening assay to identify novel hepatitis C virus antivirals

Hepatitis C virus (HCV) infection is a global health concern with chronic liver damage threatening 3% of the world's population. To date, the standard of care is a combination of pegylated interferon-alpha with ribavirin, and recently two direct acting antivirals have entered the clinics. However, because of side effects, drug resistance and viral genotype-specific differences in efficacy current and potentially also future therapies have their limitations. Here, we describe the development of a phenotypic high-throughput assay to identify new cross-genotype inhibitors with novel mechanism of action, by combining a genotype (gt) 1 replicon with the infectious HCV gt2 cell culture system. To develop this phenotypic multiplex assay, HCV reporter cells expressing RFP-NLS-IPS and gt1b replicon cells expressing NS5A-GFP were co-plated and treated with compounds followed by inoculation with gt2a HCV. At 72h post treatment, RFP translocation as a marker for HCV infection and GFP fluorescence intensity as a marker for gt1 RNA replication were measured. Additionally, the total cell number, which serves as an indicator of cytotoxicity, was determined. This phenotypic strategy supports multi-parameter data acquisition from a single well to access cross-genotypic activity, provides an indication of the stage of the viral life cycle targeted, and also assesses compound cytotoxicity. Taken together, this multiplex phenotypic platform facilitates the identification of novel compounds for drug development and chemical probes for continuing efforts to understand the HCV life cycle.

Response of hepatitis C virus to long-term passage in the presence of alpha interferon: multiple mutations and a common phenotype

Cell culture-produced hepatitis C virus (HCV) has been subjected to up to 100 serial passages in human hepatoma cells in the absence or presence of different doses of alpha interferon (IFN-α). Virus survival, genetic changes, fitness levels, and phenotypic traits have been examined. While high initial IFN-α doses (increasing from 1 to 4 IU/ml) did not allow HCV survival beyond passage 40, a gradual exposure (from 0.25 to 10 IU/ml) allowed the virus to survive for at least 100 passages. The virus passaged in the presence of IFN-α acquired IFN-α resistance as evidenced by enhanced progeny production and viral protein expression in an IFN-α environment. A partial IFN-α resistance was also noted in populations passaged in the absence of IFN-α. All lineages acquired adaptative mutations, and multiple, nonsynonymous mutations scattered throughout the genome were present in IFN-α-selected populations. Comparison of consensus sequences indicates a dominance of synonymous versus nonsynonymous substitutions. IFN-α-resistant populations displayed decreased sensitivity to a combination of IFN-α and ribavirin. A phenotypic trait common to all assayed viral populations is the ability to increase shutoff host cell protein synthesis, accentuated in infections with IFN-α-selected populations carried out in the presence of IFN-α. The trait was associated with enhanced phosphorylation of protein kinase R (PKR) and eIF2α, although other contributing factors are likely. The results suggest that multiple, independent mutational pathways can confer IFN-α resistance to HCV and might explain why no unified picture has been obtained regarding IFN-α resistance in vivo.

Pro-Inflammatory Signaling by IL-10 and IL-22: Bad Habit Stirred Up by Interferons?

Interleukin (IL)-10 and IL-22 are key members of the IL-10 cytokine family that share characteristic properties such as defined structural features, usage of IL-10R2 as one receptor chain, and activation of signal transducer and activator of transcription (STAT)-3 as dominant signaling mode. IL-10, formerly known as cytokine synthesis inhibitory factor, is key to deactivation of monocytes/macrophages and dendritic cells. Accordingly, pre-clinical studies document its anti-inflammatory capacity. However, the outcome of clinical trials assessing the therapeutic potential of IL-10 in prototypic inflammatory disorders has been disappointing. In contrast to IL-10, IL-22 acts primarily on non-leukocytic cells, in particular epithelial cells of intestine, skin, liver, and lung. STAT3-driven proliferation, anti-apoptosis, and anti-microbial tissue protection is regarded a principal function of IL-22 at host/environment interfaces. In this hypothesis article, hidden/underappreciated pro-inflammatory characteristics of IL-10 and IL-22 are outlined and related to cellular priming by type I interferon. It is tempting to speculate that an inherent inflammatory potential of IL-10 and IL-22 confines their usage in tissue protective therapy and beyond that determines in some patients efficacy of type I interferon treatment.

Hyaluronic acid-gold nanoparticle/interferon α complex for targeted treatment of hepatitis C virus infection

Gold nanoparticles (AuNPs) have been extensively investigated as an emerging delivery carrier of various biopharmaceuticals. Instead of nonspecific polyethylene glycol (PEG) conjugated interferon α (IFNα) for the clinical treatment of hepatitis C virus (HCV) infection, in this work, a target-specific long-acting delivery system of IFNα was successfully developed using the hybrid materials of AuNP and hyaluronic acid (HA). The HA-AuNP/IFNα complex was prepared by chemical binding of thiolated HA and physical binding of IFNα to AuNP. According to antiproliferation tests in Daudi cells, the HA-AuNP/IFNα complex showed a comparable biological activity to PEG-Intron with a highly enhanced stability in human serum. Even 7 days postinjection, HA-AuNP/IFNα complex was target-specifically delivered and remained in the murine liver tissue, whereas IFNα and PEG-Intron were not detected in the liver. Accordingly, HA-AuNP/IFNα complex significantly enhanced the expression of 2',5'-oligoadenylate synthetase 1 (OAS1) for innate immune responses to viral infection in the liver tissue, which was much higher than those by IFNα, PEG-Intron, and AuNP/IFNα complex. Taken together, the target-specific HA-AuNP/IFNα complex was thought to be successfully applied to the systemic treatment of HCV infection.

Simultaneous RNA quantification of human and retroviral genomes reveals intact interferon signaling in HTLV-1-infected CD4+ T cell lines

BACKGROUND

IFN-α contributes extensively to host immune response upon viral infection through antiviral, pro-apoptotic, antiproliferative and immunomodulatory activities. Although extensively documented in various types of human cancers and viral infections, controversy exists in the exact mechanism of action of IFN-α in human immunodeficiency virus type 1 (HIV-1) and human T-lymphotropic virus type 1 (HTLV-1) retroviral infections.

RESULTS

IFN-α displayed strong anti-HIV-1 effects in HIV-1/HTLV-1 co-infected MT-4 cells in vitro, demonstrated by the dose-dependent inhibition of the HIV-1-induced cytopathic effect (IC50 = 83.5 IU/ml, p < 0.0001) and p24 levels in cell-free supernatant (IC50 = 1.2 IU/ml, p < 0.0001). In contrast, IFN-α treatment did not affect cell viability or HTLV-1 viral mRNA levels in HTLV-1 mono-infected cell lines, based on flow cytometry and nCounter analysis, respectively. However, we were able to confirm the previously described post-transcriptional inhibition of HTLV-1 p19 secretion by IFN-α in cell lines (p = 0.0045), and extend this finding to primary Adult T cell Leukemia patient samples (p = 0.031). In addition, through microarray and nCounter analysis, we performed the first genome-wide simultaneous quantification of complete human and retroviral transciptomes, demonstrating significant transcriptional activation of interferon-stimulated genes without concomitant decrease of HTLV-1 mRNA levels.

CONCLUSIONS

Taken together, our results indicate that both the absence of in vitro antiproliferative and pro-apoptotic activity as well as the modest post-transcriptional antiviral activity of IFN-α against HTLV-1, were not due to a cell-intrinsic defect in IFN-α signalisation, but rather represents a retrovirus-specific phenomenon, considering the strong HIV-1 inhibition in co-infected cells.

The supplementation of acetyl-L-carnitine decreases fatigue and increases quality of life in patients with hepatitis C treated with pegylated interferon-α 2b plus ribavirin

The aim of this study was to evaluate whether supplementation of acetyl-L-carnitine (ALC) to pegylated-interferon-α 2b (Peg-IFN-α 2b) and ribavirin (RBV) improves the health-related quality of life during the treatment for chronic hepatitis C, thereby decreasing the risk of treatment discontinuation. Sixty patients with chronic hepatitis C underwent treatment with Peg-IFN-α 2b + RBV (group A; n = 29) or Peg-IFN-α 2b + RBV + ALC (group B; n = 31) for 12 months. At the end of the study, the comparison between group A and group B showed significant differences in aspartate aminotransferase (AST) (-80.9 versus -110.3; P < 0.001), alanine aminotransferase (-111.6 versus -134.7; P < 0.001), Viremia (-3.26 versus -3.82; P < 0.05), mental health (0 versus 11; P < 0.001), physical functioning (-1 versus 8; P < 0.001), role-physical (1 versus 13; P < 0.001), bodily pain (1 versus 12; P < 0.001), general health (3 versus 12; P < 0.001), vitality (3 versus 13; P < 0.001), social functioning (3 versus 10; P < 0.001), physical fatigue (2.1 versus -5.4; P < 0.001), mental fatigue (-0.7 versus -2.7; P < 0.001), and fatigue severity scale (-3.4 versus -12; P < 0.001). ALC supplementation reduced both mental and physical fatigue, improved health-related quality of life, and, therefore, has the potential to increase patient adherence to the combination regimen. This, in turn, may increase the percentage of patients achieving a sustained virological response.

Hepatitis C virus genotyping in Greece: unexpected high prevalence of genotype 5a in a Greek island

Hepatitis C virus (HCV) genotype 5 (G5) is a rare genotype reported mainly in South Africa. However, increasing data suggest the sporadic presence of this genotype in different European countries. To assess the epidemiology of HCV-G5 in Greece, genotyping was performed in 973 consecutive patients infected with HCV, referred to 7 hepatology centers throughout Greece, from January 2005 to December 2009. Genotype 5a (19 patients, 1.9%) was the fifth most prevalent genotype after genotype 1 (408 patients, 41.9%), genotype 3 (318 patients, 32.7%), genotype 4 (158 patients, 16.2%), and genotype 2 (70 patients, 7.2%). The majority of patients infected with G5 (16/19,84.2%) were referred to the General Hospital of Rhodes, an island in south-east Greece. The HCV genotype distribution in that particular island, indicates a particularly high G5 prevalence of 12.8%, after genotype 1 (40%), genotype 3 (28%), and genotype 4 (15%). Among the patients from Rhodes infected with G5 (n = 16), 13 (81.2%) were females. The mean age was 62.3 ± 6.5 years, significantly older than the patients infected with other HCV genotypes (mean age 40.6 ± 7.2, P < 0.0001). Nine out of the 16 cases (56.2%) presented features of high pre-treatment viral loads. Advanced liver fibrosis (Metavir F3-F4) was found in four out of five performed liver biopsies. Ten patients received treatment with pegylated interferon plus ribavirin and a sustained viral response were achieved in six cases. The source of infection is unknown but parenteral iatrogenic routes of transmission seem to have contributed significantly to the spread of genotype 5a in this region.

An objective assessment of conformational variability in complexes of hepatitis C virus polymerase with non-nucleoside inhibitors

A major target for antiviral therapy against hepatitis C virus (HCV) is the HCV polymerase nonstructural protein 5B (NS5B). Huge efforts have been devoted to the development of nucleoside and non-nucleoside inhibitors (NNIs) of NS5B. An offshoot of these efforts has been the structural characterization of the interaction of NS5B with NNIs by X-ray crystallography. These works have shown that the conformation of recombinant NS5B is very similar across strains, constructs and complexes, making evaluation of the long-range conformational effects of NNIs nontrivial. Using procedures appropriate to the evaluation of such minor but potentially important differences, we objectively assessed the conformational diversity in the 78 available genotype 1b NS5B structures in the Protein Data Bank. We find that there are 20 significantly different NS5B conformations available, but all are geometrically close to a closed, RNA synthesis initiation-competent one. Within this fairly restricted range, differences can be mapped to movements of NS5B domains and subregions. Most of this information is actually defined by small but significant changes in complexes with NNIs. We thus establish rigorously the moving parts of the NS5B molecular machine and the previously unrecognized hinge points that come into play upon NNI binding. We propose that NNIs binding at three of the four distinct sites specifically inhibit the initiation step by the same mechanism: they prevent NS5B's "thumb" from quite reaching the proper initiation-competent position. Furthermore, we suggest that a small number of critical hinges in the NS5B structure may emerge as sites of resistance mutations during future antiviral treatment.

The prognostic value of changes in serum ferritin levels during therapy for hepatitis C virus infection

An increase in serum ferritin levels during combined interferon-ribavirin treatment in chronic patients infected with hepatitis C virus (HCV) can occur. A study was conducted to determine whether observing the kinetics of serum ferritin levels during antiviral therapy, may assist in predicting the rate of sustained virological response. The kinetics of serum ferritin levels during antiviral therapy in treatment-naive, adherent patients with chronic HCV who had early virological response were characterized. Thirteen patients achieved sustained virological response (group 1) while eight patients did not (group 2). Pre-treatment serum ferritin levels were higher in group 2 patients. During antiviral therapy, serum ferritin levels increased in both groups. On treatment, the median increase (compared to baseline) and the calculated rate of the increase in serum ferritin levels was higher in group 1 patients (874% vs. 272%, P < 0.05, 63%/week vs. 13%/week, P = 0.024, respectively). Red blood cell lysis did not contribute to the increase in serum ferritin level. Post-treatment (1st month) serum ferritin levels in group 1 patients were lower than in group 2 patients. In addition, the degree of decline in the 1st month serum ferritin levels (from peak levels) in group 1 patients was higher (76% vs. 49%, P = 0.039). Measuring serum ferritin levels during antiviral therapy in HCV patients who had an early virological response may assist in predicting sustained virological response.

Mechanisms of non-response to antiviral treatment in chronic hepatitis C

Treatment of chronic hepatitis C virus (HCV) infection has substantially evolved over the past decade after the Consensus Conference organized by the European Association for the Study of the Liver in 1999. Since then, the standard of care (SOC) for patients with chronic hepatitis C has been the combination of pegylated interferon (pegIFN) alpha-2a or -2b and ribavirin. In patients infected with HCV genotype 1, by far the most frequent HCV genotype worldwide, such treatment leads to a cure of infection in only 40% to 50% of cases. Several factors have been identified to play a role in the outcome of therapy, including the treatment schedule, disease characteristics, viral, and host factors. Human genetic factors have been identified by a recent landmark discovery. However, these factors only partly explain the ability of IFN and ribavirin therapy to cure HCV infection. Several studies have demonstrated that, in non-responders, interferon-stimulated genes were up-regulated prior to therapy through unclear mechanisms. These findings, together with clinical, biochemical and histological data, may help better identify responders before starting therapy. This becomes particularly important as the standard treatment is physically and economically demanding. The future treatment of patients infected with HCV genotype 1 will be based on the combination of pegIFN and ribavirin with a protease inhibitor, telaprevir or boceprevir. Promising results of this triple combination in phase III clinical trials have been recently reported at the Liver Meeting 2010. With this therapy, higher cure rates will be achieved, but specific issues will be raised, such as the emergence of resistance to the protease inhibitors. The goal of this review is to discuss mechanisms involved in the non-response to current and future standard treatments.

Does interferon therapy prevent hepatocellular carcinoma in patients with chronic viral hepatitis?

Chronic hepatitis C and B are well-recognized and potentially preventable risk factors for hepatocellular carcinoma (HCC) development. Clinical and epidemiological studies suggest that therapy with interferon-α may reduce the overall risk of HCC development in patients with chronic hepatitis C, who achieve sustained virological response, but even in those who fail to eradicate the infection. In chronic hepatitis B, interferon therapy reduces the risk of HCC development in HBeAg-positive and cirrhotic patients who achieve persistent suppression of viral replication, while in HBeAg-negative patients the beneficial effect of interferon-α is not definitively confirmed. The preventive role of interferon-α after potentially curative treatment for HCC in both chronic hepatitis B and C is uncertain due to methodological flaws of the existing studies and prospective randomized controlled trials with pegylated interferon-α are needed to clarify this issue.

Mechanism of action of ribavirin in a novel hepatitis C virus replication cell system

Ribavirin (RBV) is a potential partner of interferon (IFN)-based therapy for patients with chronic hepatitis C. However, to date, its anti-hepatitis C virus (HCV) mechanism remains ambiguous due to the marginal activity of RBV on HCV RNA replication in HuH-7-derived cells, which are currently used as the only cell culture system for robust HCV replication. We investigated the anti-HCV activity of RBV using novel cell assay systems. The recently discovered human hepatoma cell line, Li23, which enables robust HCV replication, and the recently developed Li23-derived drug assay systems (ORL8 and ORL11), in which the genome-length HCV RNA (O strain of genotype 1b) encoding renilla luciferase efficiently replicates, were used for this study. At clinically achievable concentrations, RBV unexpectedly inhibited HCV RNA replication in ORL8 and ORL11 systems, but not in OR6 (an HuH-7-derived assay system). The anti-HCV activity of RBV was almost cancelled by an inhibitor of equilibrative nucleoside transporters. The evaluation of the anti-HCV mechanisms of RBV proposed to date using ORL8 ruled out the possibility that RBV induces error catastrophe, the IFN-signaling pathway or oxidative stress. However, we found that the anti-HCV activity of RBV was efficiently cancelled with guanosine, and demonstrated that HCV RNA replication was notably suppressed in inosine monophosphate dehydrogenase (IMPDH)-knockdown cells, suggesting that the antiviral activity of RBV is mediated through the inhibition of IMPDH. In conclusion, we demonstrated for the first time that inhibition of IMPDH is a major antiviral target by which RBV at clinically achievable concentrations inhibits HCV RNA replication.

von Willebrand factor antigen: a novel on-treatment predictor of response to antiviral therapy in chronic hepatitis C genotypes 1 and 4

BACKGROUND

Levels of von Willebrand factor antigen (vWF-Ag) increase during combination antiviral therapy of chronic hepatitis C (CHC). The present study investigates the association between these changes in vWF-Ag levels and response to treatment.

METHODS

Changes in levels of vWF-Ag on antiviral combination treatment in 184 patients with CHC genotype 1 or 4 infections were measured prospectively and effect on response was studied.

RESULTS

High on-treatment levels of vWF-Ag were associated with relapse (P<0.01) and low on-treatment levels with sustained virological response (SVR). Receiver operating characteristic curve analysis showed that vWF-Ag levels of <300% at week 12 of therapy have a positive predictive value (PPV) of 78% for SVR. In early virological response (EVR) patients, the PPV of vWF-Ag levels <300% at week 12 was 74%. An even higher PPV of 88% in complete EVRs (undetectable HCV RNA at week 12) was observed for the same cutoff value at week 12.

CONCLUSIONS

On-treatment levels of vWF-Ag can be utilized as an additional predictive marker for response to antiviral therapy. This is especially relevant in EVR patients because EVR alone only has a PPV of 58-72% on SVR, which increased to 74%, when factoring in vWF-Ag levels <300% at week 12, and to 88% in complete EVRs; therefore, measurement of vWF-Ag levels at week 12 is helpful. EVR patients that are above the cutoff values for vWF-Ag that make SVR very probable might profit from an extension of therapy to 72 weeks.

IL28B polymorphisms and chronic hepatitis C

Human genetic factors that influence HCV treatment responses have been identified by a recent landmark discovery. A SNP has been identified (rs12979860) located in chromosome 19,3 kb upstream of the IL28B gene that encodes IFN-λ3, which was strongly associated with the sustained virological response (SVR) to pegIFN and ribavirin in more than 1000 patients with genotype 1 chronic hepatitis C. In patients of European ancestry, as well as in African-American and Hispanic patients, the CC genotype was associated with a two-fold greater SVR rate than the TT genotype, CT being closer to TT than to CC. More information is now needed to understand the mechanisms that underlie this association.

Use of human hepatocytes to investigate HCV infection

Investigations on the biology of hepatitis C virus (HCV) have been hampered by the lack of small animal models. Efforts have therefore been directed to designing practical and robust cellular models of human origin able to support HCV replication and production in a reproducible and physiologically pertinent manner. Different systems have been constructed based on hepatoma or other cell lines, sub-genomic and genomic replicons, productive replicons, and immortalized hepatocytes. Although these models are practical for high-throughput screenings, they present several drawbacks related to the nature of the virions and the fact that the cells are not differentiated. Adult primary human hepatocytes infected with natural serum-derived HCV virions represent the model that most closely mimics the physiological situation. This chapter describes our experience with this culture model.

Early gene expression events in ferrets in response to SARS coronavirus infection versus direct interferon-alpha2b stimulation

Type I interferons (IFNs) are essential to the clearance of viral diseases, however, a clear distinction between genes upregulated by direct virus-cell interactions and genes upregulated by secondary IFN production has not been made. Here, we investigated differential gene regulation in ferrets upon subcutaneous administration of IFN-α2b and during SARS-CoV infection. In vivo experiments revealed that IFN-α2b causes STAT1 phosphorylation and upregulation of abundant IFN response genes (IRGs), chemokine receptors, and other genes that participate in phagocytosis and leukocyte transendothelial migration. During infection with SARS-CoV not only a variety of IRGs were upregulated, but also a significantly broader range of genes involved in cell migration and inflammation. This work allowed dissection of several molecular signatures present during SARS-CoV which are part of a robust IFN antiviral response. These signatures can be useful markers to evaluate the status of IFN responses during a viral infection and specific features of different viruses.

Inhibitors of the Hepatitis C Virus RNA-Dependent RNA Polymerase NS5B

More than 20 years after the identification of the hepatitis C virus (HCV) as a novel human pathogen, the only approved treatment remains a combination of pegylated interferon-α and ribavirin. This rather non-specific therapy is associated with severe side effects and by far not everyone benefits from treatment. Recently, progress has been made in the development of specifically targeted antiviral therapy for HCV (STAT-C). A major target for such direct acting antivirals (DAAs) is the HCV RNA-dependent RNA polymerase or non-structural protein 5B (NS5B), which is essential for viral replication. This review will examine the current state of development of inhibitors targeting the polymerase and issues such as the emergence of antiviral resistance during treatment, as well as strategies to address this problem.

Development of a protein biochip to identify 6 monoclonal antibodies against subtypes of recombinant human interferons

Recombinant human interferons (rhIFNs) are broadly used as effective therapeutic agents with antiviral, antitumor, and immune-modulating properties. Advances in protein biochip technology have benefited the medical community greatly, making true parallelism, miniaturization, and high throughput possible. In this study, 5 rhIFN proteins (IFN-alpha1b, IFN-alpha2a, IFN-alpha2b, IFN-beta, and IFN-gamma) were immobilized onto an N-hydroxysuccinimide (NHS)-modified gold-based biochip. The protein biochip was incubated with 6 specific mouse IgG antibodies (AK1, AK2, AK3, AK4, BK1, and CK1) against the human IFNs and then with Cy3-conjugated goat anti-mouse IgG antibody. The results showed that monoclonal antibody AK1 presented a unique binding characteristic to IFN-alpha1b. AK2 reacted in immunoassays equally with IFN-alpha2a and IFN-alpha2b. AK3 detected IFN-alpha1b, IFN-alpha2a, and IFN-alpha2b. AK4 had positive immunological responses directed to both IFN-alpha1b and IFN-alpha2b. Monoclonal antibodies BK1 and CK1 recognized epitope of IFN-beta and IFN-gamma, specifically. The assay specificity of the biochip was further confirmed by enzyme-linked immunosorbent assay (ELISA) and western blotting. Finally, 88 serum samples from patients treated with rhIFN-alpha2b were simultaneously tested on a single biochip. The result demonstrated that 6.8% (6 of 88 cases) presented positive reactions to anti-IFN-alpha2b antibodies, indicating that the patients under rhIFN-alpha2b therapy produced neutralized antibody against the IFN. The biochip format would offer a competitive alternative tool not only for facilitating characterization of IFN subtypes but also potentially for enabling clinical serum detection of corresponding antibodies directed against IFNs.

Interferon-alpha targets JAK2V617F-positive hematopoietic progenitor cells and acts through the p38 MAPK pathway

OBJECTIVE

Interferon-alpha (IFNalpha) therapy leads to hematological remissions and a reduction of the JAK2V617F allele burden in patients with polycythemia vera (PV). In this study, the cellular target by which IFNalpha affects hematopoiesis in PV patients was evaluated.

MATERIALS AND METHODS

CD34(+) cells were isolated from normal bone marrow and the peripheral blood of patients with PV and were treated in vitro with each of the three commercially available forms of IFNalpha: IFNalpha 2b, pegylated IFNalpha 2a (Peg-IFNalpha 2a), and pegylated IFNalpha 2b (Peg-IFNalpha 2b).

RESULTS

Each form of IFNalpha was equally potent in suppressing hematopoietic colony formation by normal CD34(+) cells, but Peg-IFNalpha 2a and IFNalpha 2b were more effective than Peg-IFNalpha 2b in inhibiting burst-forming unit erythroid-derived colony formation by PV CD34(+) cells. In addition, exposure of PV CD34(+) cells to equal doses of Peg-IFNalpha 2a and IFNalpha 2b resulted in a 38% to 40% reduction in the proportion of JAK2V617F-positive hematopoietic progenitor cells (HPC), while equivalent doses of Peg-IFNalpha 2b did not reduce the number of malignant HPC. Further studies explored the mechanism by which IFNalpha induced PV HPC growth inhibition. Treatment of Peg-IFNalpha 2a increased the rate of apoptosis of PV CD34(+) cells and the phosphorylation/activation of p38 mitogen-activated protein kinase in PV CD34(+) cells, while the p38-specific inhibitor SB203580 reversed the growth inhibition and apoptosis induced by Peg-IFNalpha 2a.

CONCLUSION

These data suggest that low doses of IFNalpha selectively and directly suppress PV JAK2V617F HPC and that these agents act through the p38 mitogen-activated protein kinase pathway.

Novel interferons for treatment of hepatitis C virus

The current standard of care for treatment of hepatitis C is pegylated interferon and ribavirin. Despite the large number of new oral agents under development, interferon will likely remain the backbone of future therapy. Interferon has unique antiviral and immunomodulatory properties, which have been critical in limiting resistance to protease inhibitors and improving efficacy. Hence, optimizing pharmacokinetics and promoting adherence to interferon dosing regimens will become even more critical as new regimens enter the clinical arena. This review highlights novel interferons under development that may offer therapeutic advantages over the formulations currently available.

Cellular models for the screening and development of anti-hepatitis C virus agents

Investigations on the biology of hepatitis C virus (HCV) have been hampered by the lack of small animal models. Efforts have therefore been directed to designing practical and robust cellular models of human origin able to support HCV replication and production in a reproducible, reliable and consistent manner. Many different models based on different forms of virions and hepatoma or other cell types have been described including virus-like particles, pseudotyped particles, subgenomic and full length replicons, virion productive replicons, immortalised hepatocytes, fetal and adult primary human hepatocytes. This review focuses on these different cellular models, their advantages and disadvantages at the biological and experimental levels, and their respective use for evaluating the effect of antiviral molecules on different steps of HCV biology including virus entry, replication, particles generation and excretion, as well as on the modulation by the virus of the host cell response to infection.

Development of hepatitis C virus vaccines: challenges and progress

Development of an effective vaccine against the hepatitis C virus (HCV) has long been defined as a difficult challenge due to the considerable variability of this RNA virus and the observation that convalescent humans and chimpanzees could be re-infected after re-exposure. On the other hand, progress in the understanding of antiviral immune responses in patients with viral clearance has elucidated key mechanisms playing a role in the control of viral infection. Studies investigating prophylactic vaccine approaches in chimpanzees have confirmed that the induction and maintenance of strong helper and cytotoxic T-cell immune responses against multiple viral epitopes is necessary for protection against viral clearance and chronic infection. A multispecific B-cell response, resulting in rapid induction of cross-neutralizing antibodies may assist cellular responses. Therapeutic vaccine formulations currently being evaluated in clinical trials are facing the fact that the immune system of chronic carriers is impaired and needs the restoration of T-cell functions to enhance their efficacy.

A cell-based bicistronic lentiviral reporter system for identification of inhibitors of the hepatitis C virus internal ribosome entry site

This report describes the development, optimization and implementation of a persistent cell-based system to test inhibitors of hepatitis C (HCV) translation. The assay is based on a heterologous human immunodeficiency virus-1/simian immunodeficiency virus (HIV-1/SIV) lentiviral vector expressing the bicistronic cassette containing the firefly and renilla luciferase genes, respectively, as reporters, and the HCV internal ribosome entry site (IRES) inserted in between, under the control of the cytomegalovirus (CMV) promoter. The drug target in this assay is the HCV IRES, the activity of which leads to modulation of the renilla luciferase gene expression under its control, which is monitored by luminometry. The system has been validated using interferon (IFN), which is still the only consensual antiviral agent against HCV infection, associated with ribavirin. This bicistronic vector, extended to other viral IRESs and assayed in different cell lines, exhibited weak cell tropism, allowing its broad use in gene therapy, which frequently needs a multicistronic transfer vector to follow the expression of a gene of interest inside the target cells with the aid of a reporter, a drug selection marker, or a suicide gene, expressed from the same transcript.