Viral, host and interferon-related factors modulating the effect of interferon therapy for hepatitis C virus infection

Assessment of interleukin 28B genotype as a predictor of response to combined therapy with pegylated interferon plus ribavirin in HCV infected Egyptian patients

BACKGROUND AND AIM

Single nucleotide polymorphisms (SNPs) of interleukin 28B (IL28B) gene is associated with spontaneous clearance and variable response to combined therapy with pegylated interferon (PEG-IFN) and ribavirin (RBV) in chronic hepatitis C virus (HCV) infected patients. This study aimed at assessing the value of IL28B rs8099917 gene polymorphism in predicting sustained virological response (SVR) among HCV infected Egyptian patients treated with PEG-IFN and RBV.

METHODS

Our study was conducted on 153 chronic HCV infected patients treated with PEG-IFN and RBV. Genotyping of rs8099917 near the IL-28B gene was performed by Real Time PCR using Taq-Man probe assay.

RESULTS

The overall SVR was achieved in 49.6% of patients. Patients with TT genotype showed significantly higher SVR rate than minor allele (TG/GG) carriers (74% vs. 26%, P=0.004). Logistic regression analysis revealed that TT carriers had 2.8 higher chance for SVR achievement than G allele carriers TG/GG (OR=2.8, 95% CI=1.4-5.6, P=0.004). Younger age, male sex and low activity grading were significant predictors of SVR (P=0.003, P=<0.001 and P<0.001 respectively). High pretreatment AST levels and advanced liver fibrosis were negative predictors of SVR (P=0.04 and P<0.001 respectively).

CONCLUSION

IL28B genotype is a significant pre-treatment predictor of response to PEG-IFN/RBV in HCV infected Egyptian patients.

Hepatitis C virus impairs TLR3 signaling and inhibits IFN-λ 1 expression in human hepatoma cell line

Toll-like receptor 3 (TLR3) activation plays an important role in the innate immune responses to viral infections. We show here that the activation of TLR3 signaling pathway by poly I:C, a synthetic mimic of dsRNA, could induce high-level expression of interferon (IFN)-λ1 in a hepatoma cell line. The induced IFN-λ1 contributed to poly I:C-mediated inhibition of hepatitis C virus (HCV) Japanese fulminant hepatitis-1 (JFH-1) replication in Huh7 cells. This inhibitory effect of poly I:C on HCV replication, however, was compromised by HCV infection of Huh7 cells. Investigation of the mechanisms showed that HCV infection suppressed the expression of poly I:C-induced IFN-λ1 and IFN-stimulated genes [IFN-stimulated gene 56 (ISG-56), myxovirus resistance A (MxA) and 2'-5'-oligoadenylate synthetase 1 (OAS-1))], the key antiviral elements in IFN signaling pathway. Among the HCV nonstructural (NS) proteins tested, NS3/4A, NS5A and NS5B had the ability to inhibit poly I:C-induced IFN-λ1 expression in Huh7 cells. These observations provide the experimental evidence that HCV and its proteins impair TLR3 signaling and inhibit intracellular IFN-λ1/ISG expression in a hepatoma cell line, which may account for HCV persistence in the liver.

Serum Serotonin Levels are Associated with Antiviral Therapy Outcomes in Patients with Chronic Hepatitis C

The role of serotonin in contributing to viral clearance has not been investigated in patients with chronic hepatitis C (HCV). In this prospective study we collected blood samples from 39 patients prior to and during antiviral therapy. Participants completed mood rating scales to monitor psychiatric symptoms, and serum serotonin and tryptophan levels were measured. Significant differences in serotonin levels were found between patients who achieved sustained viral responses (SVRs) and those who did not. Regression analysis revealed that serotonin was the only variable with a statistically significant relationship with antiviral therapy outcomes, even after controlling for other variables known to be associated with outcomes. Baseline serum serotonin levels, in combination with other variables such as degree of liver fibrosis, may be clinically useful for identifying patients in whom HCV can be cleared by antiviral therapy. Additional clinical predictors that could forecast treatment success are needed so that interventions to improve SVR rates, and reduce side effects, can be developed.

Analysis of variables and interactions among variables associated with a sustained virological response to pegylated interferon alfa-2a plus ribavirin in hepatitis C virus genotype 3-infected patients

BACKGROUND

The recommended standard therapeutic regimen for chronic hepatitis patients with hepatitis C virus (HCV) genotype 3 is pegylated interferon plus ribavirin for 24 weeks. The aim of the present study was to evaluate treatment efficacy and variables predictive of treatment success, interactions among variables contributing to a response to therapy, and the utility of the rapid virological response (RVR; week 4 virological response) to predict treatment outcomes in HCV genotype 3-infected patients in routine clinical practice.

METHODS

We prospectively studied baseline and during-treatment factors associated with a sustained virological response (SVR) in HCV genotype 3-infected patients who received pegylated interferon alfa-2a (PEG-IFN α2a) 180 μg/week plus ribavirin 800 mg daily for 24 weeks and who were followed for 24 weeks after the completion of treatment.

RESULTS

Four hundred and twenty-six treated patients were included in the analysis; 320 (75.1%) showed an SVR. The following factors were assessed for their ability to predict SVR by means of univariable and multivariable logistic regression analysis: patient age, sex, pre-treatment viral load, pre-treatment alanine aminotransferase (ALT), body mass index (BMI), and RVR. Four factors - age, pre-treatment viral load, pre-treatment ALT, and RVR - were statistically significant predictors of SVR (p<0.05) in the univariable analysis. Factors showing a significant association with SVR were assessed by multivariable logistic regression analysis. In the multivariable analysis, independent factors associated with SVR were the attainment of RVR (odds ratio (OR) 11, 95% confidence interval (CI) 6.15-20.69; p<0.0001), patient age ≤40 years (OR 4.2, 95% CI 2.30-7.96, p<0.0001), and a low pre-treatment viral load (≤8 × 10(5) IU/ml; OR 3.4, 95% CI 1.87-6.25; p<0.0001). The effect of RVR in patients aged >40 years was more pronounced than in those aged ≤40 years: 81.1% of patients aged >40 years who achieved an RVR had an SVR, whereas only 7.5% of patients aged >40 years who did not achieve an RVR had an SVR (p<0.05).

CONCLUSIONS

RVR is an independent variable that is predictive of SVR. Moreover older patients (>40 years) who achieve an RVR are likely to have an SVR, while patients who do not achieve an RVR and who have a high pre-treatment viral load (>8 × 10(5) IU/ml) are unlikely to have an SVR.

Extent of liver inflammation in predicting response to interferon α & Ribavirin in chronic hepatitis C patients: a cohort study

Background

Liver inflammation due to HCV infection leads to fibrosis, which is an independent predictor of treatment response to interferon therapy in Chronic Hepatitis C (CHC) patients. This relationship has not been studied for liver inflammation on pretreatment liver biopsy and End of Treatment Response (ETR). ALT is a less invasive test than liver biopsy for measuring liver inflammation. Aim of this study was to compare ETR to Interferon α (recombinant Interferon) & Ribavirin in CHC patients having higher and lower grades of liver inflammation and to determine the diagnostic accuracy of pretreatment ALT for grades of liver inflammation.

Methods

A retrospective cohort of 876 naïve CHC patients, who completed Interferon α & Ribavirin for 24 weeks, was studied for ETR. Pretreatment grade of inflammation on liver biopsy was taken as the exposure variable. It was classified as high if there was moderate or severe and low if there was minimal or mild. Multivariable logistic regression modeling was performed. Diagnostic accuracy of pretreatment ALT for liver inflammation grades was determined by computing Area Under the Receiver Operator Curve (AUROC).

Results

Of all patients, 672 having diagnostic liver biopsy and ETR available were analyzed. Among them, 103 had high and 569 had low grades of liver inflammation. Mean age was 36.9 (SD 9.1) years, with patients with high grades being older than those with low grades inflammation (p = 0.03). High grades of liver inflammation was associated with ETR (RR 1.17, 95% CI 1.12–1.18) adjusting for age, Total Leukocyte count (TLC) and pretreatment levels of ALT, irrespective of liver fibrosis. This relation remained significant for ‘bridging fibrosis and cirrhosis’ and not for ‘no’ or ‘portal fibrosis’. AUROC of pretreatment ALT for males and females was moderately accurate for severe inflammation compared to minimal inflammation and less accurate for high grades compared to low grades.

Conclusions

ETR in patients with higher grades of liver inflammation was 17% higher than those with lower grades irrespective of fibrosis and 9% higher for bridging fibrosis and cirrhosis. Pretreatment ALT was moderately accurate for severe inflammation only on liver biopsy in both males and females.

Current status of liver disease in Korea: hepatitis C

Chronic hepatitis C (CHC) is the third most common cause of chronic liver disease and hepatocellular carcinoma (HCC) in Korea, following hepatitis B virus (HBV) infection and alcohol. HCV prevalence among Koreans older than 40 years of age has been estimated to be 1.29%. The prevalence of CHC increases with age, with the peak prevalence at the age of 60 or older. Blood transfusions have generated no risk of HCV infection since April 1991, when routine screening for anti-HCV in blood donors was adopted in Korea. Although injection drug use seems to be one of the most important risk factors of HCV infection among young adults in urban areas, the majority of CHC patients are not associated with injection drug use. Exposure to acupuncture was identified as a significant risk factor among older adults in rural areas. The mean age of patients with HCV-related cirrhosis and HCC was consistently about 10 years above that of patients associated with HBV. Genotypes 1b and 2a are the two most common types with almost equal proportions, and other genotypes are extremely rare. Korean patients with CHC have a high likelihood of responding to combination therapy with pegylated interferon and ribavirin, with a sustained virological response rate of 60-70% in patients with genotype 1 and 85-90% in those with genotype 2.

HCV genetic variability: from quasispecies evolution to genotype classification

HCV is a ssRNA virus belonging to the Flaviviruses and is found worldwide worldwide in humans. Following primary infection, persistent infection develops in more than 85% of cases, which in up to 30% of cases, may progress to liver disease, cirrhosis and hepatocellular carcinoma. The virus presents a high degree of genetic variability owing to the combination of a lack of proofreading by the RNA-dependent RNA polymerase and a high level of viral replication. This genetic variability allows the classification of genotypes, subtypes, isolates and quasispecies to which epidemiological and pathogenetic significance may be associated. The features and biological implications of HCV variability and of quasispecies dynamics in infection transmission, mechanisms of chronicity and resistance to antiviral therapy are discussed.

Predictors of sustained virological response to a 48-week course of pegylated interferon alfa-2a and ribavirin in patients infected with hepatitis C virus genotype 4

BACKGROUND AND OBJECTIVES

Knowledge of the predictors of sustained viral response (SVR) to pegylated interferon (PEG-INF) alfa-2a and ribavirin (RBV) therapy in patients with hepatitis C genotype-4 (HCV-4) is crucial for selecting patients who would benefit most from therapy. We assessed the predictors of SVR to this combination therapy in Saudi patients with chronic HCV-4 infection.

PATIENTS AND METHODS

This retrospective study included 148 patients with HCV-4 infection who underwent clinical, biochemical and virological assessments before treatment and at 12, 24, 48 and 72 weeks post-treatment.

RESULTS

Of the 148 patients, 90 (60.8%) were males. Mean (SD) for age was 48.5 (12.7) years and BMI was 27.9 (7.5) kg/m(2). Seventy-nine of 148 (60.1%) patients were treatment naïve and 110 (74.3%) underwent pre-treatment liver biopsy. Eighteen (12.2%) patients did not complete therapy because of side effects or they were lost to follow up. Early virological response was achieved in 84 of 91 (92.3%) patients. In the 130 (87.8%) patients who completed therapy, 34 (26.2%) were non-responders and 96 (63.8%) achieved end-of-treatment virological response (ETVR). SVR and virological relapse (24 weeks after ETVR) occurred in 66/130 (50.7%) and 30/130 (31.2%) patients, respectively. Compared to relapsers, sustained responders were significantly younger (P=.005), non-diabetic (P=.005), had higher serum albumin (P=.028), lower alpha-fetoprotein level (P=.026), lower aspartate aminotransferase (AST) (P=.04) levels, and were treatment-naïve (P=.008). In a multivariate regression analysis, the independent predictors of SVR were younger age (P=.016), lower serum AST (P=.012), and being treatment naïve (P=.021).

CONCLUSION

Approximately half of HCV-4 patients who complete the course of combination therapy achieve an SVR, especially if they are young, treatment naA ve and have lower AST levels.

Predictors of a sustained virological response in patients with genotype 4 chronic hepatitis C

OBJECTIVES

To determine the clinical, biological, virological and histological predictive factors associated with a sustained virological response (SVR) to combined interferon therapy among Egyptian patients infected by genotype 4 hepatitis C virus (HCV).

PATIENTS AND METHODS

Individual data from 250 patients with genotype 4 chronic hepatitis C, treated with different regimens of combined interferon, were analysed. The primary end point was SVR defined as undetectable HCV RNA by polymerase chain reaction (PCR) 24 weeks after the end of treatment. Multivariate logistic regression analysis was performed to select the independent prognostic parameters associated with SVR.

RESULTS

A sustained virological response was achieved among 137/250 (54.8%) patients. Baseline factors independently and negatively associated with SVR were serum alpha-fetoprotein (AFP) level (above 0.3 upper limit of normal) [odds ratio (OR)=0.5, 95% confidence interval (CI): 0.2-0.8], severe fibrosis (Metavir score >F2) (OR=0.4, 95% CI: 0.2-0.8), presence of steatosis (OR=0.5, 95% CI: 0.3-0.97) and standard interferon treatment (OR=0.4, 95% CI: 0.2-0.8).

CONCLUSIONS

Among genotype 4 chronic hepatitis C patients, severe fibrosis, severe steatosis, treatment with standard interferon and a high serum AFP level were all negatively associated with SVR. Pretreatment serum AFP level should be considered in the routine assessment of factors predictive of a treatment response.

Correlation between pre-treatment quasispecies complexity and treatment outcome in chronic HCV genotype 3a

Pre-treatment HCV quasispecies complexity and diversity may predict response to interferon based anti-viral therapy. The objective of this study was to retrospectively (1) examine temporal changes in quasispecies prior to the start of therapy and (2) investigate extensively quasispecies evolution in a group of 10 chronically infected patients with genotype 3a, treated with pegylated α2a-Interferon and ribavirin.

The degree of sequence heterogeneity within the hypervariable region 1 was assessed by analyzing 20–30 individual clones in serial serum samples. Genetic parameters, including amino acid Shannon entropy, Hamming distance and genetic distance were calculated for each sample. Treatment outcome was divided into (1) sustained virological responders (SVR) and (2) treatment failure (TF).

Our results indicate, (1) quasispecies complexity and diversity are lower in the SVR group, (2) quasispecies vary temporally and (3) genetic heterogeneity at baseline can be use to predict treatment outcome.

We discuss the results from the perspective of replicative homeostasis.

Gene-gene and gene-environment interactions in interferon therapy for chronic hepatitis C

INTRODUCTION

In studies of pharmacogenomics, it is essential to address gene-gene and gene-environment interactions to describe complex traits involving pharmacokinetic and pharmacodynamic mechanisms. In this work, our goal is to detect gene-gene and gene-environment interactions resulting from an analysis of chronic hepatitis C patients' clinical factors including SNPs, viral genotype, viral load, age and gender.

MATERIALS & METHODS

We collected blood samples from 523 chronic hepatitis C patients who had received interferon and ribavirin combination therapy. Based on the treatment strategy for chronic hepatitis C patients, we focused our search for candidate genes involved in pathways related to interferon signaling and immunomodulation. To investigate gene-gene and gene-environment interactions, we implemented an artificial neural network-based method for identifying significant interactions between clinical factors with the fivefold crossvalidation method and permutation tests. The artificial neural network model was trained by an algorithm with an adaptive momentum and learning rate.

RESULTS

A total of 20 SNPs were selected from six candidate genes including adenosine deaminase-RNA-specific (ADAR), caspase 5 (CASP5), interferon consensus sequence binding protein 1 (ICSBP1), interferon-induced protein 44 (IFI44), phosphoinositide-3-kinase catalytic gamma polypeptide (PIK3CG), and transporter 2 ATP-binding cassette subfamily B (TAP2) genes. By applying our artificial neural network-based approach, IFI44 was found in the significant two-locus, three-locus and four-locus gene-gene effect models, as well as in the significant two-factor and three-factor gene-environment effect models. Furthermore, viral genotype remained in the best two-factor, three-factor and four-factor gene-environment models. These results support the hypothesis that IFI44 and viral genotype may play a role in the pharmacogenomics of interferon treatment. In addition, our approach identified a panel of ten clinical factors that may be more significant than the others for further study.

CONCLUSION

We demonstrated that our artificial neural network-based approach is a promising method to assess the gene-gene and gene-environment interactions for interferon and ribavirin combination treatment in chronic hepatitis C patients by using clinical factors such as SNPs, viral genotype, viral load, age and gender.

Sustained virologic response to peginterferon alpha-2a and ribavirin in 335 patients with chronic hepatitis C: a tertiary care center experience

BACKGROUND/AIM

This retrospective study assessed the efficacy, safety, and the predictors of sustained viral response (SVR) to a 48-week-course of peginterferon alpha-2a (Pegasys) and ribavirin combination therapy in 335 consecutive Saudi patients with chronic hepatitis C virus (HCV) infection.

MATERIALS AND METHODS

Clinical, biochemical, and virological parameters were collected at time 0 (pretreatment) and at 12, 24, 48, and 72 weeks posttreatment. The mean +/- SD age was 49.1 +/- 13.0 years; 229 (68.4%) were males, mean +/- SD body mass index was 27.8 +/- 7.4, 85 (25.4%) were diabetic, 25 (7.5%) had renal impairment, 136 (40.6%) had previously received interferon +/- ribavirin therapy, and 247 (73.7%) underwent pretreatment liver biopsy. Patients with genotypes 1, 2 or 3, 4 and mixed genotype were 60 (22.15%), 30 (11.0%), 148 (54.4%), and 34 (12.5%), respectively.

RESULTS

Early viral response (>or=2-log10 HCV-RNA decline 12 weeks posttreatment) was achieved in 253 (75.3%). Patients who completed 48 weeks of treatment were 292 (87.1%); of these, 121 (75.6%) achieved ETVR, 161 (55.1%) continued to have SVR and 60 (20.5%) had a viral relapse following end-of-treatment response, that is 48.1 and 17.9% of all patients (n = 335), respectively. Nonresponders (NR) were 71 (24.3%) patients and 43 (12.8%) were unable to complete treatment (due to side effects or loss to follow up). Compared to the relapsers, patients with SVR were significantly younger (P = 0.000), nondiabetics (P = 0.015), had higher serum albumin (P = 0.007), had less pretreatment inflammatory grade (P = 0.011), infected with genotypes 2 or 3 (P = 0.014), and treatment-naïve patients (P = 0.001). However, in stepwise multivariate logistic regression analysis, only treatment naiveté and low pretreatment inflammatory score were the independent predictors of SVR (P = 0.005 and P = 0.018, respectively).

CONCLUSION

Combination therapy, if tolerated and completed, is effective in treating chronic HCV patients, especially those with no previous interferon therapy and lower pretreatment inflammatory grade.

HCV NS5A inhibits interferon-alpha signaling through suppression of STAT1 phosphorylation in hepatocyte-derived cell lines

BACKGROUND/AIMS

HCV NS5A appears to play an important role in HCV resistance to IFN-alpha but the molecular mechanism is not fully elucidated. Most studies regarding the involvement of signal transducer and activator of transcription 1 (STAT1) in inhibition of IFN-alpha signaling by NS5A were performed in non-hepatic cell lines and their relevance may be debatable.

METHODS

We analyzed the effects of NS5A on IFN-alpha signaling through STAT1 phosphorylation in three hepatocyte-derived cell lines, Hep3B, J5 and Huh7. Interaction of NS5A and STAT1 was also investigated with co-immunoprecipitation and confocal microscopy.

RESULTS

IFN-alpha induces STAT1 activation in Hep3B cells in a dose- and time-dependent manner. Transient or stable NS5A expression inhibits STAT1 phosphorylation in a dose-dependent manner in hepatocyte-derived cell lines, whereas the levels of STAT1 phosphorylation remain unchanged in non-hepatocyte HeLa and COS7 cells despite increasing amounts of NS5A. The NS5A may interact with STAT1, specifically, the N-terminal 488 amino acids of STAT1. Furthermore, NS5A inhibits activation of interferon-stimulated gene factor 3 (ISGF3) and interferon-stimulated response element (ISRE)-driven gene expression, as demonstrated by electrophoretic mobility shift assay and luciferase assay, respectively.

CONCLUSIONS

NS5A may interact with STAT1 and inhibit IFN-alpha signaling through suppression of STAT1 phosphorylation specifically in hepatocyte-derived cells.

Triple therapy of initial high-dose interferon with ribavirin and amantadine for patients with chronic hepatitis C

AIMS

We previously reported the potential effect of combination therapy of an initial high-dose interferon (IFN) and amantadine on the eradication of HCV-RNA in patients with chronic hepatitis C. The additive effects of amantadine on interferon and ribavirin combination therapy remain controversial. In this study we investigated the efficacy of initial high-dose IFN with ribavirin and amantadine on the virological response in patients with chronic hepatitis C with a high viral load of genotype 1b.

METHODS

Twenty-two patients with high viral loads of genotype 1b hepatitis C virus were enrolled in this pilot study. Patients were administered IFN-beta for four weeks and then IFN-alpha2b for 22 weeks with daily oral administration of ribavirin and amantadine.

RESULTS

A sustained virological response (SVR) was shown in 31.8% (seven of 22 patients). With the naïve patients, the SVR rate was 21.4% (three of 14 patients). In patients who could not eradicate HCV-RNA by previous IFN monotherapy, the SVR rate was 50% (four of eight patients).

CONCLUSION

Triple therapy with an initial high dose of IFN with ribavirin and amantadine may be effective, especially for chronic hepatitis C IFN-retreatment patients with a high viral load of genotype 1b.

Hepatitis C virus genetic variability in patients undergoing antiviral therapy

Hepatitis C virus (HCV) has been the subject of intense research and clinical investigations due to its worldwide prevalence and major role in chronic liver disease. Like most RNA viruses, HCV circulates in vivo as a complex population of different but closely related viral variants, commonly referred to as a quasispecies. Recent studies suggest that ribavirin might exert an antiviral effect against HCV through both mutagenic effect and an impairment of RNA replication. The introduction of alpha interferon (IFN-alpha) plus ribavirin combination therapy was an important breakthrough in the treatment of chronic HCV infection. However, the rate of sustained virological response is still unsatisfactory, particularly in patients infected with HCV genotype 1. Viral persistence, a hallmark of HCV, may result from a dynamic control of the host response by the virus. In children with chronic HCV infection, the viral population is initially highly homogeneous, but diversifies during prolonged infection which seems to be a common event during chronic hepatitis C in childhood. Coinfection of human immunodeficiency virus 1 (HIV-1) patients by HCV can complicate the treatment of these patients with highly active antiretroviral therapy (HAART). HIV coinfection is associated with a decrease of HCV quasispecies variability, which appears to be reversed by effective HAART.

Preparation and characterization of a potent, long-lasting recombinant human serum albumin-interferon-alpha2b fusion protein expressed in Pichia pastoris

A long-lasting recombinant human serum albumin-interferon-alpha2b fusion protein (rHSA/IFNalpha2b) was prepared and its structure and biological activities were studied. rHSA/IFNalpha2b was expressed in methylotrophic yeast Pichia pastoris with HSA's natural signal peptide and purified by dye affinity chromatography, hydrophobic interaction chromatography, ion exchange chromatography and Sephadex G25. Purity of the prepared rHSA/IFNalpha2b was greater than 97% analyzed by non-reduced SDS-PAGE and RP-HPLC. Structure and biological activities of the prepared rHSA/IFNalpha2b were characterized by physical, chemical and biological methods. Its pI was 5.3 and showed a single band on IEF gel. Molecular weight determined by MALDI-TOF was 86004.3+/-29.2. Amino-terminal and carboxyl-terminal amino acid sequences were identical to predicted sequence. Its specific activity in vitro was 6.3+/-0.8x10(5) IU/mg fusion protein, retaining about 1.4% of that of unmodified rIFNalpha on a molar basis. After administered in monkeys, significant increases of 2',5'-oligoadenylate synthetase activity relative to IFN-alpha were maintained for 14 days in serum and the rHSA/IFNalpha2b showed more potent biological activity than IFN-alpha on a molar basis. Therefore, markedly improved in vivo biological activity of rHSA/IFNalpha2b could exhibit more potent antiviral activity than IFNalpha2b in future clinical trials.

An artificial neural network approach to the drug efficacy of interferon treatments

INTRODUCTION

Interferon taken alone or in combination with ribavirin can be used for the treatment of persons with chronic hepatitis C. It is highly desirable, both clinically and economically, to establish tools to distinguish responders from nonresponders and to predict possible outcomes of the treatments. In this work, our goal is to develop a prediction model resulting from the analysis of chronic hepatitis C patients' single nucleotide polymorphisms, viral genotype, viral load, age and gender, to predict the responsiveness of interferon combination treatment.

MATERIALS AND METHODS

We collected blood samples from 523 chronic hepatitis C patients that had received interferon and ribavirin combination therapy. Based on the current treatment strategy for chronic hepatitis C patients, we focused our search for candidate genes involved in pathways related to interferon signaling and immunomodulation. With artificial neural network algorithms, we then developed pattern recognition methodologies to achieve predictions among the patients. The artificial neural network model was trained by an algorithm with an adaptive momentum and learning rate.

RESULTS

There were seven single nucleotide polymorphisms selected from six candidate genes including adenosine deaminase-RNA-specific, caspase 5, interferon consensus sequence binding protein 1, interferon-induced protein 44, phosphoinositide-3-kinase catalytic gamma polypeptide and transporter 2 ATP-binding cassette subfamily B genes. We further applied the artificial neural network algorithms with these seven single nucleotide polymorphisms, viral genotype, viral load, age and gender information to build tools for predicting the responsiveness of interferon. Based on the fivefold cross-validation method to evaluate the performance, the model achieved a high success rate of prediction.

CONCLUSION

We demonstrated that a trained artificial neural network model is a promising method for providing the inference from factors such as single nucleotide polymorphisms, viral genotype, viral load, age and gender to the responsiveness of interferon.

2'-,5'-Oligoadenylate synthetase response ratio predicting virological response to PEG-interferon-α2b plus ribavirin therapy in patients with chronic hepatitis C

OBJECTIVE

Although all the mechanisms of elimination of hepatitis C virus (HCV) by Interferon (IFN) have not been fully elucidated, the 2'-5'-oligoadenylate (2-5A) system is one of the mechanisms of the antiviral effect of IFN. Consequently, the measurement of 2'-5'-oligoadenylate synthetase (2-5AS) activity could be useful for the evaluation of IFN treatment. This retrospective study was aimed at assessing whether 2-5AS activity functions as a clinical marker of virological response to PEG-interferon-alpha2b (PEG-IFN) plus ribavirin therapy of chronic hepatitis C.

METHODS

The 32 patients included in this study had high viral loads of serum HCV-RNA of genotype 1b with chronic hepatitis C. All the patients received a regimen of PEG-IFN plus ribavirin for 48 weeks, and were then divided into two groups: one group (effective group) with undetectable serum HCV-RNA levels at 24 weeks (n = 22) of therapy, the other group (ineffective group) with persistent presence of HCV-RNA in serum at 24 weeks (n = 10). The 2-5AS activity in serum was measured 2, 8 and 12 weeks before initial administration.

RESULTS

The 2-5AS response ratio (measured value/measured value of baseline 2-5AS) at 2, 8 and 12 weeks after the administration in the effective group was significantly higher than that in the ineffective group.

CONCLUSIONS

These results suggest that the ratio of 2-5AS is closely related to the antiviral effect, and that the measurement of 2-5AS response ratio may be a useful clinical parameter of virological response to PEG-IFN plus ribavirin therapy of chronic hepatitis C.

Global transcriptional response to interferon is a determinant of HCV treatment outcome and is modified by race

Interferon (IFN)-alpha-based therapy for chronic hepatitis C is effective in fewer than 50% of all treated patients, with a substantially lower response rate in black patients. The goal of this study was to investigate the underlying host transcriptional response associated with interferon treatment outcomes. We collected peripheral blood mononuclear cells from chronic hepatitis C patients before initiation of IFN-alpha therapy and incubated the cells with or without IFN-alpha for 6 hours, followed by microarray assay to identify IFN-induced gene transcription. The microarray datasets were analyzed statistically according to the patients' race and virological responses to subsequent IFN-alpha treatment. The global induction of IFN-stimulated genes (ISGs) was significantly greater in sustained virological responders compared with nonresponders and in white patients compared with black patients. In addition, a significantly greater global induction of ISGs was observed in sustained virological responders compared with nonresponders within the group of white patients. The level of IFN-induced signal transducer and activator of transcription (STAT) 1 activation, a key component of the Janus kinase (JAK)-STAT signaling pathway, correlated with the global induction of ISGs and was significantly higher in white patients than in black patients. In conclusion, both treatment outcome and race are associated with different transcriptional responses to IFN-alpha. Because this difference is evident in the global induction of ISGs rather than a selective effect on a subset of such genes, key factors affecting the outcome of IFN-alpha therapy are likely to act at the JAK-STAT pathway that controls transcription of downstream ISGs.

SCH 503034, a mechanism-based inhibitor of hepatitis C virus NS3 protease, suppresses polyprotein maturation and enhances the antiviral activity of alpha interferon in replicon cells

Cleavage of the hepatitis C virus (HCV) polyprotein by the viral NS3 protease releases functional viral proteins essential for viral replication. Recent studies by Foy and coworkers strongly suggest that NS3-mediated cleavage of host factors may abrogate cellular response to alpha interferon (IFN-alpha) (E. Foy, K. Li, R. Sumpter, Jr., Y.-M. Loo, C. L. Johnson, C. Wang, P. M. Fish, M. Yoneyama, T. Fujita, S. M. Lemon, and M. Gale, Jr., Proc. Natl. Acad. Sci. USA 102:2986-2991, 2005, and E. Foy, K. Li, C. Wang, R. Sumpter, Jr., M. Ikeda, S. M. Lemon, and M. Gale, Jr., Science 300:1145-1148, 2003). Blockage of NS3 protease activity therefore is expected to inhibit HCV replication by both direct suppression of viral protein production as well as by restoring host responsiveness to IFN. Using structure-assisted design, a ketoamide inhibitor, SCH 503034, was generated which demonstrated potent (overall inhibition constant, 14 nM) time-dependent inhibition of the NS3 protease in cell-free enzyme assays as well as robust in vitro activity in the HCV replicon system, as monitored by immunofluorescence and real-time PCR analysis. Continuous exposure of replicon-bearing cell lines to six times the 90% effective concentration of SCH 503034 for 15 days resulted in a greater than 4-log reduction in replicon RNA. The combination of SCH 503034 with IFN was more effective in suppressing replicon synthesis than either compound alone, supporting the suggestion of Foy and coworkers that combinations of IFN with protease inhibitors would lead to enhanced therapeutic efficacy.

Hepatitis C virus inhibits intracellular interferon alpha expression in human hepatic cell lines

The chronicity of hepatitis C virus (HCV) infection raises the question of how HCV is able to persist in hepatic cells. We show that human primary hepatocytes and human hepatic cell lines (Huh7 and HepG2) spontaneously produce interferon (IFN)-alpha that is inhibited in the HCV replicon cells (Huh.8 and FCA-1). Silencing IFN-alpha gene expression by IFN-alpha small interfering RNA (siRNA) in the HCV replicon cells resulted in increased HCV replicon expression. The activation of IFN-alpha expression by interferon regulatory factor (IRF-7) led to the inhibition of HCV replicon expression, whereas the anti-IFN-alpha receptor antibody could partially block IRF-7-mediated HCV replicon inhibition. In addition, the blockade of IFN-alpha receptor by anti-IFN-alpha receptor antibody on the replicon cells increased HCV replicon expression. Among the HCV nonstructural (NS) proteins tested, NS5A is the most potent inhibitor of IFN-alpha expression by the hepatic cells. Investigation of the mechanism of HCV action on IFN-alpha showed that IRF-7-induced IFN-alpha promoter activation was inhibited in the HCV replicon cells. Furthermore, IRF-7 expression was restricted in the HCV replicon cells. In conclusion, we provide direct evidence that HCV undermines the intracellular innate immunity of the target cells, which may account for HCV persistence in hepatic cells.

Involvement of PKR and RNase L in translational control and induction of apoptosis after Hepatitis C polyprotein expression from a vaccinia virus recombinant

Background

Hepatitis C virus (HCV) infection is of growing concern in public health with around 350 million chronically infected individuals worldwide. Although the IFN-α/rivabirin is the only approved therapy with 10–30% clinical efficacy, the protective molecular mechanism involved during the treatment is still unknown. To analyze the effect of HCV polyprotein expression on the antiviral response of the host, we developed a novel vaccinia virus (VV)-based delivery system (VT7-HCV7.9) where structural and nonstructural (except part of NS5B) proteins of HCV ORF from genotype 1b are efficiently expressed and produced, and timely regulated in mammalian cell lines.

Results

Regulated transcript production and viral polypeptide processing was demonstrated in various cell lines infected with the recombinant VT7-HCV7.9, indicating that the cellular and viral proteolytic machineries are functional within these cells. The inducible expression of the HCV polyprotein by VV inhibits the synthesis of both host and viral proteins over the time and also induces apoptosis in HeLa and HepG2-infected cells. These effects occur accompanying with the phosphorylation of the translation initiation factor eIF-2α. In cells co-infected with VT7-HCV7.9 and a recombinant VV expressing the dominant negative eIF-2α-S51A mutant in the presence of the inductor isopropyl-thiogalactoside (IPTG), protein synthesis is rescued. The IFN-inducible protein kinase PKR is responsible for the translational block, as demonstrated with PKR-/- and PKR+/+ cell lines. However, apoptosis induced by VT7-HCV7.9 is mediated by the RNase L pathway, in a PKR-independent manner.

Conclusion

These findings demonstrate the antiviral relevance of the proteins induced by interferon, PKR and RNase L during expression from a VV recombinant of the HCV polyprotein in human cell lines. HCV polyprotein expression caused a severe cytopathological effect in human cells as a result of inhibition of protein synthesis and apoptosis induction, triggered by the activation of the IFN-induced enzymes PKR and RNase L systems. Thus, the virus-cell system described here highlights the relevance of the IFN system as a protective mechanism against HCV infection.

Serum adiponectin correlates with viral characteristics but not histologic features in patients with chronic hepatitis C

BACKGROUND/AIMS

Adiponectin induces insulin sensitivity and modulates inflammatory responses. We thus studied the implications of adiponectin in patients with chronic hepatitis C virus (HCV) infection inherently linked to insulin resistance.

METHODS

We analyzed the association of serum adiponectin levels with clinical, virologic, and histologic findings in 95 naive Taiwanese patients with chronic hepatitis C before and after antiviral therapy.

RESULTS

At baseline, 14 (15%) of the 95 patients were obese and 26 (27%) had type 2 diabetes mellitus. Fifty-seven patients were infected with HCV genotype 1 and 38 with genotype 2. Steatosis and periportal fibrosis was present in 44 (46%) and 69 (73%), respectively. In multivariate analysis, male gender, insulin resistance, high HCV load and genotype 2 were significantly associated with a lower serum adiponectin level. In contrast, intrahepatic gene expression of adiponectin receptors was higher in genotype 2 compared with genotype 1. Serum adiponectin level did not correlate with other clinical or histologic parameters. After treatment, change of steatosis also did not correlate with the change of adiponectin level (P=0.61).

CONCLUSIONS

Adiponectin correlated with hepatitis C viral factors at both serum and liver tissue levels. The interactions among adiponectin, insulin resistance and chronic HCV infection merit further studies.

Adiponectin levels among patients with chronic hepatitis B and C infections and in response to IFN-alpha therapy

AIMS

The study was designed to survey the change of adiponectin levels before and after interferon-alpha (IFN-alpha) therapy in patients with chronic hepatitis B and C infections.

METHODS

Twenty-one biopsy-proved patients with chronic hepatitis B (10 cases) and hepatitis C (11 cases) were given IFN-alpha for a total of 24 weeks. Fasting plasma glucose, insulin and adiponectin levels were obtained before and 12 weeks after completion of IFN-alpha therapy. Insulin suppression test was conducted before and within 1 week after IFN-alpha therapy.

RESULTS

The change of adiponectin levels differed significantly between responders (eight cases) and non-responders (13 cases) to IFN-alpha treatment (-4.8+/-2.2 vs. 0.5+/-1.0 microg/ml, P=0.03). After adjusting for age, gender and change in body mass index, the study found the change of adiponectin levels still significantly related to the response to IFN-alpha (P=0.04). When hepatitis B virus (HBV) and hepatitis C virus (HCV)-infected patients were separately analyzed, the adiponectin levels reported a trend to decrease in HCV responders (11.9+/-3.2 vs. 10.8+/-3.0 microg/ml, P=0.02, n=4) and HBV responders (17.7+/-4.1 vs. 9.2+/-1.0 microg/ml, P=0.10, n=4). In addition, a significant decrease of steady-state plasma glucose in insulin suppression test was noted in responders (13.6+/-1.8-11.7+/-1.2 mmol/l, P=0.03), but not in non-responders (12.3+/-1.1-11.0+/-1.0 mmol/l, P=0.20), after IFN-alpha therapy.

CONCLUSIONS

IFN-alpha resulted in a decrease of serum adiponectin levels but an improvement of insulin resistance in responders to the treatment. The result contradicts previous concept of the relationship between insulin resistance and adiponectin levels. Whether and how the augmented immune response, which was supposed to result from the disappearance or the profound down-regulation of the virus or viral antigens in responders to IFN-alpha treatment, contributes to the lowering of adiponectin levels needs to be further investigated.

Heterologous production of five Hepatitis C virus-derived antigens in three Saccharomyces cerevisiae host strains

In this study, the production of recombinant Hepatitis C virus (HCV) derived proteins from transformed Saccharomyces cerevisiae yeast cells is reported. Three different yeast strains (GRF18U, BY4743-4A and CENPK 113-5D) have been transformed for the intracellular expression of five antigens of different dimensions (from 32.8 to 85.2 kDa), all derived from the non-structural (NS) region of different HCV viruses' genotypes and posed under the control of a glycolytic promoter. The putative trans-membrane domains contained in four antigens seem responsible of their accumulation as protein aggregates. Good productions of the smaller and of the bigger antigens (50 and 30 mgl(-1), respectively) have been observed in simple flask batch cultures. Productions are strongly dependent from the genetic background of the yeast host and from the cellular localization of the antigen, while they appear independent from the growth rate of the transformed hosts. For every recombinant antigen tested, the highest production levels were achieved with the CENPK 113-5D-host strain, while the GRF18U strain shows symptoms of a heavily stressed phenotype.

Pegylated interferon-alpha 2b-ribavirin combination in Egyptian patients with genotype 4 chronic hepatitis

Egypt has a high prevalence rate of hepatitis C (HCV) infection and as much as 90% is genotype 4. Response to interferon (IFN) varies with viral genotype and degree of fibrosis. Genotype 4 is poorly sensitive to standard IFN and IFN-ribavirin combination. We evaluated pegylated interferon (PEG-IFN)-alpha2b in our patients. Sixty-one patients with compensated chronic HCV genotype 4 were enrolled in two groups: group A (31 patients) received IFN-alpha2b 3 MU three times per week and group B (30 patients) received 1.5 mug/kg PEG-IFN-alpha2b once weekly. Ribavirin was added to each regimen in a dose of 800-1200 mg based on body weight. Patients were followed up for 24 weeks to assess the sustained response (SR). End-of-treatment response (ETR) was achieved in 11 of 31 patients (35.48%) in group A, and 13 of 30 patients (43.33%) in group B (P < 0.05). Only eight patients in group A and 10 in group (B) achieved a sustained virological response (25.8 and 33.3%, respectively) (P < 0.05). By computing ETR, SR or relapse and pretreatment baseline data (pretreatment, viral load, alanine transaminases, necroinflammatory and hepatic fibrosis), both inter- and intragroup, no significant correlations could be detected. In terms of safety and tolerability, PEG-IFN-alpha2b and IFN-alpha2b were comparable. In spite of mild insignificant increase in ETR and SR with the pegylated form, the poor response of genotype 4 in Egypt (genotype 4a) to different forms of IFNs may be related to an intrinsic resistance to the direct antiviral effect of IFN.

Mutations within the hepatitis C virus genotype 1b E2-PePHD domain do not correlate with treatment outcome

The hepatitis C virus (HCV) envelope protein 2 (E2) interacts in vitro with the interferon alpha (IFN-alpha)-inducible double-stranded RNA-activated protein kinase, suggesting a possible mechanism by which HCV may evade the antiviral effects of IFN-alpha. Variability in the part of the HCV E2 gene encoding the carboxy-terminal part of the protein, which includes the interaction domain (E2-PePHD), was explored in 25 patients infected with HCV genotype 1b and receiving IFN-alpha therapy. PCR products were generated and sequenced for 15 patients with a sustained response and for 10 patients with no virological response after treatment with IFN-alpha and ribavirin. PePHD amino acid sequences were obtained for isolates from serum collected before and during treatment, after 2 months in responders, and after 6 months in nonresponders. Quasispecies analysis of the pretreatment PePHD region was performed for isolates from patients displaying amino acid substitutions in this domain on direct sequencing. The E2-PePHD sequence was highly conserved in both resistant and susceptible genotype 1b strains and was identical to the prototype HCV type J sequence. No significant emergence of PePHD mutants during therapy was observed in our clonal analysis, and sporadic mutations and treatment outcomes were not found to be correlated. The PePHD sequence before or during treatment cannot be used to predict reliably the outcome of treatment in HCV type 1b-infected patients.

Prediction of Treatment Outcome in Chronic Hepatitis C Patients Based on Early Viral Dynamics during High-Dose Induction Interferon and Ribavirin Therapy

OBJECTIVE

In chronic hepatitis C, early viral load decline after interferon administration is dose dependent and reflects the intrinsic viral susceptibility to the antiviral action of interferon. We examined whether the augmented suppression of susceptible viral loads by high-dose induction interferon could possibly discriminate responsive patients from non-responsive patients at an early stage of treatment.

METHODS

Fifty-nine chronic hepatitis C patients were randomly allocated to receive one of two treatment regimens; 3 MU interferon three times weekly plus ribavirin 1,000 mg/day for 24 weeks in the CR group (n = 30), and the same regimen as in the CR group except 10 MU interferon daily for the first week in the HR group (n = 29). Changes in viral loads during the first week of treatment were analyzed in terms of sustained virological response (SVR).

RESULTS

The positive predictive values of undetectable (<100 IU/ml) or low serum HCV RNA (<2,000 IU/ml) after 1 week of treatment for SVR were 100% in both treatment groups, whereas the negative predictive values of the low viral titer were 91% in the HR group and 70% in the CR group.

CONCLUSION

One-week virological response to high-dose induction interferon/ribavirin combination therapy is more predictive of SVR than conventional combination therapy in chronic hepatitis C.

Characteristic sequence changes of hepatitis C virus genotype 2b associated with sustained biochemical response to IFN therapy

In hepatitis C virus (HCV) genotype 2b infection, viral eradication (sustained viral response; sVR) is obtained in about 40% by interferon monotherapy, whereas a considerable proportion of non-sVR patients exhibit sustained biochemical response (sBR) showing normal biochemical values despite persistent viraemia. However, the mechanism of sBR has not yet been established. In this study, we analysed serial changes in full-length sequences of HCV genotype 2b before and after interferon (IFN) therapy in five patients with sBR and five with no response (NR; persistent viraemia and abnormal biochemical values after IFN therapy). The overall substitution rate of amino acids in the full-length HCV genome was higher in the sBR group than in the NR group [2.22 +/- 0.48 (10(-3) changes/site/year) vs 1.04 +/- 0.30: P = 0.002]. When the genetic changes were analysed for individual HCV proteins, the sBR group had significantly higher substitution rates of amino acid in NS4A [8.82 +/- 2.80 (10(-3) changes/site/year) vs 0: P = 0.001]. These amino acid changes in sBR were mainly located in the binding motifs of HLA class I molecules including those frequently found in the Japanese population. These results demonstrated that the greater amino acid changes of HCV arising during interferon therapy are associated with the establishment of sBR. Although functional significance of these changes awaits further investigation, the finding that amino acid changes in NS4A in sBR patients are mainly located in the HLA class I binding motifs illustrated the potential roles of the escape mutations of HCV genome from CTLs in the decreasing activities of hepatitis in sBR.

Lack of a strong association between HLA class II, tumour necrosis factor and transporter associated with antigen processing gene polymorphisms and virological response to alpha-interferon treatment in patients with chronic hepatitis C

The aim of the study was to investigate whether polymorphisms of the HLA class II, tumour necrosis factor (TNF) and transporter associated with antigen processing (TAP) genes influence the response to alpha-interferon in patients with chronic hepatitis C. Twenty-seven sustained responders and 55 non-responders to alpha-interferon monotherapy were investigated. HLA-DRB1, DQA1, DQB1, TNFA, TNFB, TAP1 and TAP2 alleles were determined by PCR-based molecular techniques. Sustained virological response was defined as undetectable serum hepatitis C virus (HCV) RNA for at least 3 years after the end of treatment. Probability (P) values were corrected for the number of alleles tested (Pc). Viral genotype 1b was more frequent in responders than in non-responders (56% vs. 26%, P = 0.009). HLA-DQB1*02 occurred less frequently in responders than in non-responders (14.8% vs. 29%, Pc not significant). HLA-DRB1*11 and DQB1*0602 were found in 22.2% and 9.3% of responders and in 10.9% and 1.8% of non-responders, respectively (Pc not significant). There was no difference in the distribution of TNF alleles in the two groups. Twenty-four (88.8%) responder patients as compared with 34 (61.8%) non-responders were TAP1*0101 homozygous (Pc not significant). Thus, in European Caucasoids with chronic hepatitis C, we could not demonstrate a strong association between HLA class II, TNF, and TAP gene polymorphisms and response to interferon treatment.

Unique features of hepatitis C virus capsid formation revealed by de novo cell-free assembly

The assembly of hepatitis C virus (HCV) is poorly understood, largely due to the lack of mammalian cell culture systems that are easily manipulated and produce high titers of virus. This problem is highlighted by the inability of the recently established HCV replicon systems to support HCV capsid assembly despite high levels of structural protein synthesis. Here we demonstrate that up to 80% of HCV core protein synthesized de novo in cell-free systems containing rabbit reticulocyte lysate or wheat germ extracts assembles into HCV capsids. This contrasts with standard primate cell culture systems, in which almost no core assembles into capsids. Cell-free HCV capsids, which have a sedimentation value of approximately 100S, have a buoyant density (1.28 g/ml) on cesium chloride similar to that of HCV capsids from other systems. Capsids produced in cell-free systems are also indistinguishable from capsids isolated from HCV-infected patient serum when analyzed by transmission electron microscopy. Using these cell-free systems, we show that HCV capsid assembly is independent of signal sequence cleavage, is dependent on the N terminus but not the C terminus of HCV core, proceeds at very low nascent chain concentrations, is independent of intact membrane surfaces, and is partially inhibited by cultured liver cell lysates. By allowing reproducible and quantitative assessment of viral and cellular requirements for capsid formation, these cell-free systems make a mechanistic dissection of HCV capsid assembly possible.

Association of interferon-alpha-induced depression and improved treatment response in patients with hepatitis C

Thirty-nine patients with hepatitis C viral infection on interferon-alpha (IFN-alpha) therapy were monitored weekly using the Beck Depression Inventory (BDI). Thirteen of thirty-nine patients (33%) developed IFN-alpha-induced major depressive disorder (MDD). During the course of IFN-alpha therapy, patients who became depressed were treated with citalopram, a selective serotonin reuptake inhibitor (SSRI) antidepressant. Results indicated that: (1) IFN-alpha response rates were significantly higher in those patients who developed IFN-alpha-induced MDD than in those who did not (end-of-treatment response (ETR) rates: 61.5% versus 26.9% and sustained viral response (SVR) rates: 38.5% versus 11.5%), (2) male patients with ETR to IFN-alpha therapy were, on average, approximately 33 pounds lighter in body weight than male patients who did not respond, and (3) gender, race, past history of MDD, and past history of substance abuse were not significantly associated with ETR. In conclusion, our findings suggest that IFN-alpha-induced MDD may be a predictor of a positive response to IFN-alpha therapy, or an indication of optimal dosing.

Lack of Interferon Sensitivity-Determining Region in the Genome of Hepatitis B Virus Genotype Ba

Background/aims

In chronic hepatitis B, both host and viral factors may predict the response to interferon (IFN) treatment. Whether IFN sensitivity-determining regions exist within the hepatitis B virus (HBV) genomic background remains largely unknown. We therefore performed full-length viral genomic comparison between HBVs obtained from IFN responders and non-responders.

Methods

We enrolled 18 HBV genotype Ba patients who had received 24-week IFN 5 MU three times weekly and were followed monthly for 12 months post-treatment. There were 10 responders and eight non-responders. Pretreatment full-length viral nucleotide consensus sequence was obtained. In six non-responders and four responders, post-treatment viral nucleotide sequence was further compared with their corresponding pre-treatment specimens. In addition, the average number of nucleotide substitutions of the HBV quasispecies was compared between three responders and three non-responders.

Results

HBV nucleotide consensus sequence was identical between responders and non-responders. We found 0–15 (mean 7.7) nucleotide substitutions in the post-treatment HBV genome in the six non-responders and 0–14 (mean 3.8) nucleotide substitutions in the four responders, respectively. Genetic complexity of HBV quasispecies was comparable between responders and non-responders.

Conclusions

Our results suggest that an IFN sensitivity-determining region might not exist within the genome of HBV genotype Ba. Host factors and virus–host interactions may be more important in determining the response to IFN treatment.

Cyclooxygenase 2 (COX2)-prostanoid pathway and liver diseases

Cycloocygenases 2 (COX2)-prostanoid pathway plays important and complex roles in the pathogenesis of various liver diseases. Most studies indicated that COX2-prostanoid pathway might suppress hepatic fibrogenesis by decreasing proliferation, migration, and contractility of hepatic stellate cells (HSCs). In animal model, COX2-prostanoid pathway increases portal hypertension, which can be reduced by treatment with COX2 inhibitor. In cirrhosis, COX2-prostanoid pathway may reduce formation of ascites by enhancing free water excretion, and protect gastric mucosa from ulcerative insults. Aberrant expression of COX2 has been well associated with hepatocarcinogenesis. COX2 inhibitors can effectively suppress proliferation of hepatocellular carcinoma (HCC) cells. This provided rationale for further testing COX2 inhibitors as clinical agents for HCC chemoprovention. Further studies will be needed to examine how COX2 inhibitors affect pathogenesis of various liver diseases.

Comparative study of the efficacy of an induction dose of interferon-alpha2b with ribavirin compared with standard combined treatment in naive patients with chronic hepatitis C

The efficacy and secondary effects of an induction dose of interferon-alpha2b (IFN-alpha2b) with ribavirin compared with standard combined treatment in naive patients with chronic hepatitis C infection were compared. A prospective study was undertaken between March 1998 and November 2001 in which 84 Spanish hospitals took part. Six hundred and fourteen naive patients (age range 18-65 years) diagnosed with chronic hepatitis C virus (HCV) infection and without cirrhosis or co-infection by other viruses, were included. Patients were divided into two groups. Group A (n = 304) received induction treatment with a daily dose of 5 MU of IFN-alpha2b for 4 weeks, followed by 5 MU three times a week with ribavirin (1000-1200 mg/day, according to weight) until completing 1 year of treatment. Group B (n = 310) received the standard dose of IFN-alpha2b of 3 MU three times per week for 48 weeks together with ribavirin (1000-1200 mg/day, according to weight). Both groups were completely comparable according to age, gender, body weight, transaminase levels, genotype, viral load and hepatic inflammatory activity (Knodell Index). No control group was included for ethical reasons. Pegylated interferon was not available at the time of the study. Serum baseline samples were collected for the determination of genotype. Samples were also collected at baseline, weeks 4, 12, 24, 48 and 72, in order to detect and quantify HCV-RNA. The efficacy of treatment was evaluated by means of sustained viral response (SVR) characterized by persistent negativity of HCV-RNA at the end of the follow-up period. At week 4, the response to treatment was greater in group A (49.6%) compared with group B (34.5%) (P = 0.0002), and was maintained until week 12 (64.1% compared with 55.8% respectively) (P = 0.03). These differences disappeared at week 24, when group A (69%) was compared with group B (65%) (NS). At week 48, the response rate for group A was 50.6% compared with group B 47.4% (NS), and at week 72, the SVR in group A was 46% compared with 40.3% for group B (NS). The global SVR was 43.1%. On analysing the response to treatment according to genotype and viral load, we found that the induction treatment was slightly superior in patients with genotype 1 and an elevated viral load (>2 x 10(6) copies/ml). They achieved a SVR in group A of 39.1% compared with 25.5% in group B (P < 0.05). However, this slight improvement obtained in group A, was achieved at the expense of a greater percentage of dropouts compared with group B (6.4% vs 2.2%, P < 0.01); a greater rate of side effects (58.5 vs 36.7%, P < 0.05) and also a greater percentage of neutropenia (3.1% vs 0.9%, P < 0.05). The induction treatment presented a better initial response, but this was not maintained at the end of treatment, and did not improve the results obtained with the standard treatment. Although the patients with genotype 1 and elevated viral load had a better response with the induction treatment, this was accompanied by a greater percentage of dropouts and secondary effects. It would be interesting to repeat this type of study in the future, using pegylated interferon.

Nadir CD4+ T Cell Count Predicts Response to Subcutaneous Recombinant Interleukin-2

Community Program for Clinical Research on AIDS 059 was a multicenter study conducted among human immunodeficiency virus (HIV)-infected individuals with CD4+ cell counts > or =300 cells/mm3 who were randomly assigned to receive antiretroviral therapy with or without intermittent subcutaneously administered recombinant interleukin-2 (rIL-2). To identify factors associated with a response to IL-2, a secondary analysis was performed that included the subset of rIL-2 recipients who were able to complete all 3 initial treatment cycles. Predictors of a change in CD4+ cell count between baseline and 1 month after the start of treatment cycle 3 were examined in a multivariate model that included sex, race, body surface area, rIL-2 dose, HIV load, and both baseline and nadir CD4+ cell count. The combination of race and sex (P=.027) and the nadir CD4+ cell count (P=.005) were significant predictors of mean CD4+ cell count response. Baseline CD4+ cell count had no significant effect. The strong association between nadir CD4+ cell count and CD4+ cell count response suggests that immunologic losses resulting from HIV-mediated CD4+ cell depletion may be irreversible.

Mutations in nonstructural 5A gene of hepatitis C virus and its response to interferon alfa

AIM

To investigate the relationship between NS5A_2209-2248 sequences and response to interferon therapy, and whether there is an IFN sensitivity determining region(ISDR) in the region of NS5A_2209-2248.

METHODS

We analyzed 11 patients with chronic HCV 1b infection who had received interferon alfa therapy for six months. Pretreatment serum samples were analyzed. The amino acid sequence of NS5A_2209-2248 was determined by direct sequencing of the HCV genome amplified by the polymerase chain reaction.

RESULTS

Among the 11 patients, only 1 was intermediate type, all the others were wild type. 2 of wild type patients showed complete response. Others were nonresponders. There was no significant difference in nucleotide and amino acid sequences between the two groups.The nucleotide and amino acid sequences changed after IFN treatment in one nonresponder.

CONCLUSION

The NS5A_2209-2248 region was highly conservative. In Chinease patients with chronic HCV 1b infection, there was no correlation between response to interferon and mutations in the NS5A gene. HCV quasispecies changed after IFN therapy.

HLA class I B44 is associated with sustained response to interferon + ribavirin therapy in patients with chronic hepatitis C

OBJECTIVE

The aim of this study was to assess the influence of host genetic factors on response to combination therapy for chronic hepatitis C infection.

METHODS

Patients with biopsy-proved chronic hepatitis C infection were treated with interferon alone (n = 143) or combined therapy of interferon + ribavarin (n = 105; 46 treatment naïve, 59 relapsers). Human leukocyte antigen (HLA) class I was determined by microlymphocytotoxicity and class II by polymerase chain reaction-single specific oligonucleotide. The two biallelic tumor necrosis factor-alpha promoter polymorphisms were studied by a polymerase chain reaction-amplification refractory mutation system. Other variables measured were viral genotype, hepatitis C virus RNA load, liver function tests, and ferritin concentration.

RESULTS

Univariate analysis indicated that patients bearing HLA B44+, DRB1*03, infected by genotype non-1, with higher concentrations of transaminases and shorter duration of infection showed a higher sustained response (SR) rate than those on combination therapy. HLA class II and TNF-alpha promoter polymorphisms were not related to SR. In multivariate analysis, non-1 genotype (OR 2.42, 95% CI 1.12-5.55, p = 0.026) and HLA B44+ (OR 4.84, 95% CI 1.3-17.8, p = 0.017) were the independent variables associated with SR. However, HLA B44+ was not associated with SR in patients treated with interferon alone.

CONCLUSIONS

HLA class I B44 is related to a higher rate of SR in combination therapy but not in interferon monotherapy, whereas HLA class II, tumor necrosis factor-alpha -238A or -308A seem not to influence response to the antiviral therapy. These findings may be of value in therapy selection for hepatitis C-infected patients.

Ribavirin and interferon is effective for hepatitis C virus clearance in hepatitis B and C dually infected patients

Ribavirin and interferon (IFN) are an effective treatment in 30% to 60% of patients with chronic hepatitis C. Whether they are also effective in dually infected patients with hepatitis B and C is unknown. Twenty-four patients with chronic hepatitis seropositive for both hepatitis B surface antigen and antibody to HCV received ribavirin 1,200 mg daily for 6 months, together with 6 million units (MU) IFN-alpha 2a thrice weekly for 12 weeks and then 3 MU for another 12 weeks. Serum HCV RNA was positive in 21 patients (group I, serum HBV DNA positive in 17 patients) and negative in 3 patients (group II, all HBV DNA positive) by Amplicor (Cobas Amplicor Monitor, Roche Diagnostics, Branchburg, NJ). Serum alanine aminotransferase (ALT), HCV RNA, and hepatitis B virus (HBV) DNA were monitored regularly for 12 months. Another 30 patients with chronic hepatitis C alone receiving the same regimen, served as controls. The serum HCV clearance rate in group I patients (43%) was comparable with that in controls (60%, P =.63) 24 weeks posttreatment. The serum ALT normalization rate in group I and group II patients was 43% and 0%, respectively, 24 weeks posttreatment. After treatment, resurgence of HBV and HCV was encountered in 4 group I patients and 1 group II patient, respectively. In conclusion, in hepatitis B and C dually infected patients, combination of IFN with ribavirin can achieve a sustained HCV clearance rate comparable with hepatitis C alone. In dually infected patients, the treatment may alter the dominant, ruling hepatitis virus.

Interferon alfa regulated gene expression in patients initiating interferon treatment for chronic hepatitis C

Interferon alfa (IFN-alpha) is an approved therapeutic agent for chronic hepatitis C. To directly characterize the effects of IFN-alpha in humans, we used microarrays to profile gene expression in peripheral blood mononuclear cells (PBMCs) from hepatitis C patients treated with IFN-alpha. Seven patients were studied using two strategies: (1) in vivo: PBMCs were collected immediately before the first dose of IFN-alpha, and 3 and 6 hours after the dose; (2) ex vivo: PBMCs that were collected before the first IFN-alpha dose were incubated with IFN-alpha for 3 and 6 hours. The microarray datasets were analyzed with significance analysis of microarrays (SAM) to identify genes regulated by IFN-alpha. We identified 516 named genes up-regulated at least 2-fold, at a false discovery rate (FDR) of less than 1%. In vivo and ex vivo studies generated similar results. No genes were identified as regulated differently between these 2 experimental conditions. The up-regulated genes belonged to a broad range of functional pathways and included multiple genes thought to be involved in the direct antiviral effect of IFN-alpha. Of particular interest, 88 genes directly relating to functions of immune cells were up-regulated, including genes involved in antigen processing and presentation, T-cell activation, lymphocyte trafficking, and effector functions, suggesting that IFN-alpha up-regulates multiple genes involving different aspects of immune responses to enhance immunity against hepatitis C virus. In conclusion, IFN-alpha-inducible genes can be identified in human PBMCs in vivo as well as ex vivo. Signature changes associated with different treatment outcomes may be found among these genes.

Porphyria cutanea tarda as a Predictor of Poor Response to Interferon Alfa Therapy in Chronic Hepatitis C

BACKGROUND

Porphyria cutanea tarda (PCT) is sometimes associated with hepatitis C virus chronic infection. The aim of this study was to describe the effect of interferon alfa (IFN-a) in the treatment of patients with chronic hepatitis C and PCT.

METHODS

We treated a total of 66 patients with chronic hepatitis C with IFN-a 2b (5 MU t.i.w.) for 12 months. Twenty-two of these patients suffered from PCT as well. These patients differed from patients without PCT in that they were men, past history of alcohol abuse and HFE gene mutations were more common and the source of infection was almost always unknown.

RESULTS

Sustained virologie response was obtained in 19.7% of the 66 treated patients, 27.3% in the non-PCT group and 4.5% in the PCT group (P < 0.05). This difference could not be ascribed to the difference in sex of patients, history of alcohol abuse, HCV genotype or iron status.

CONCLUSION

Multivariate logistic regression analysis revealed that PCT is independently and significantly associated with non-sustained response to IFNa therapy. In conclusion, patients with chronic hepatitis C and PCT rarely responded to IFNa treatment.

Effects of quasi-species heterogeneity of HBV on response to IFN-a therapy

AIM: To study effects of quasi-species heterogeneity of hepatitis B virus (HBV) on response to interferon(IFN)-α therapy.

METHODS: Serum quasi-species heterogeneity of HBV in 20 patients (10 responders and 10 non-responders) with chronic hepatitis B before administration of IFN-α was detected with conformation-sensitive gel electrophoresis (CSGE), and the relationship between response to IFN-α and quasi-species heterogeneity of HBV was analyzed.

RESULTS: No significant difference in levels of HBV DNA between responders (7.27×10¹⁰±8.79×10¹⁰) and non-responders (5.16×10¹⁰±5.13×10¹⁰) before IFN-α therapy was found (P > 0.05). But the quasi-species complexity and genetic diversity in non-responders were significantly higher than those in responders (8.30±1.89 vs 18.5±2.68, P < 0.001 and 0.926±0.008 vs 0.869±0.016, P < 0.001).

CONCLUSION: The level of quasi-species heterogeneity of HBV was reversely associated with the probability of response to IFN-α therapy.

HLA-A2-restricted cytotoxic T lymphocyte activity during interferon beta therapy in patients with chronic hepatitis C

BACKGROUND AND AIMS

Hepatitis C virus (HCV)-specific cytotoxic T lymphocytes (CTL) may contribute to viral clearance and liver cell injury in patients with chronic hepatitis C. In the present study, we attempted to determine the serial HCV-specific CTL activity during interferon-beta (IFN-beta) therapy in patients with chronic hepatitis C and whether there is any relationship between the CTL response and clinical response to IFN-beta therapy.

METHODS

Eight HLA-A2-positive patients with chronic hepatitis C were treated initially with 6 million U/ml of IFN-beta every day for 8 weeks and then 3 times weekly for the subsequent 16 weeks. Peripheral blood mononuclear cells (PBMC) were collected before the start, 4 weeks after the start, and after the end of IFN treatment and were stimulated with 2 peptides corresponding to core sequences, which were previously reported to have an HLA-A2 restricted-CTL epitopes. Cytolytic activity was determined by a standard 51Cr-release assay using allogenic HLA-matched EBV-transformed B lymphoblastoid cell lines (B-LCL).

RESULTS

HCV-specific CTL responses were detected in 2 of the 8 patients before treatment with IFN-beta. One of 2 patients was not observed HCV-specific CTL responses after 4 weeks of IFN-beta treatment, however these two patients showed CTL responses at the end of IFN-beta treatment, and finally HCV-RNA was negative. In addition, HCV-specific CTL responses were observed in 4 patients after 4 weeks of IFN-beta treatment. Three of these 4 patients showed CTL responses only at 4 weeks after IFN-beta treatment. However, there were no differences between clinical parameters or between IFN efficacy in HCV specific CTL response-positive (n = 4) and -negative (n = 4) patients at 4 weeks after the start of IFN-beta treatment.

CONCLUSIONS

These findings suggest that there are few relations between peripheral HCV-specific CTL response and clinical response to IFN therapy in patients with chronic hepatitis C, although IFN enhances the host immune response against HCV synergistically with antiviral activities.

Inhibition of the replication of a hepatitis C virus-like RNA template by interferon and 3'-deoxycytidine

The development of low molecular weight inhibitors of hepatitis C virus (HCV) replication has been hindered by the lack of a good cell-based system that models the entire HCV replication cycle. To date the only two therapies approved for the treatment of HCV infection are interferon (IFN)-alpha and the nucleoside analogue, ribavirin. We have created a cell-based system that allows for the accurate quantification of the replication of an HCV-like RNA template by proteins that are encoded for by the HCV genome. The system consists of a cell line that constitutively produces luciferase in response to the production of functional HCV replicative proteins. The 293B4alpha cell line has been formatted into a semi-high throughput, cell-based screen for inhibitors of HCV replication. When these cells were treated with either IFN-alpha or -beta, luciferase production decreased in a dose-responsive manner. Counterscreening these molecules in another cell line, 293SVLuc, in which luciferase production in not dependent the presence of functional HCV proteins, showed that the inhibition of luciferase in the 293B4alpha cell line was due to inhibition of the replication of the HCV-like RNA template and not anti-cellular or -luciferase activity. Moreover, when the 293B4alpha cell line was treated with the ribonucleoside analogue, 3'-deoxycytidine, luciferase decreased in a dose-responsive manner. 3'-deoxyguanosine and 3'-deoxyuridine did not inhibit luciferase production and 3'-deoxyadenosine was too cytotoxic to determine if it had any anti-HCV activity.

Pharmacokinetic and pharmacodynamic studies of a human serum albumin-interferon-alpha fusion protein in cynomolgus monkeys

Interferon-alpha (IFN-alpha) is indicated for the treatment of certain viral infections including hepatitis B and C, and cancers such as melanoma. The short circulating half-life of unmodified IFN-alpha makes frequent dosing (daily or three times weekly) over an extended period (6-12 months or more) necessary. To improve the pharmacokinetics of IFN-alpha and decrease dosing frequency, IFN-alpha was fused to human serum albumin producing a new protein, Albuferon. In vitro comparisons of Albuferon and IFN-alpha showed similar antiviral and antiproliferative activities, although Albuferon was less potent on a molar basis than IFN-alpha. Pharmacokinetic and pharmacodynamic properties of the fusion protein were enhanced in monkeys. After a single intravenous injection (30 microg/kg,) clearance was 0.9 ml/h/kg, and the terminal half-life was 68 h. After 30 microg/kg subcutaneous injection, apparent clearance (clearance divided by bioavailability) was 1.4 ml/h/kg, the terminal half-life was 93 h, and bioavailability was 64%. The rate of clearance of Albuferon was approximately 140-fold slower, and the half-life 18-fold longer, than for IFN-alpha given by the subcutaneous route in other monkey studies. Sera from Albuferon-treated monkeys demonstrated dose-related antiviral activity for > or =8 days based on an in vitro bioassay, whereas antiviral activity from IFN-alpha-treated animals was only slightly elevated relative to vehicle on day 0. Significant increases in 2',5'-oligoadenylate synthetase mRNA relative to IFN-alpha- or vehicle-treated animals were maintained for > or =10 days after subcutaneous dosing. The improved pharmacokinetics of Albuferon are accompanied by an improved pharmacodynamic response suggesting that Albuferon may offer the benefits of less frequent dosing and a potentially improved efficacy profile compared with IFN-alpha.

To interfere and to anti-interfere: the interplay between hepatitis C virus and interferon

As popular strategies used by numerous viruses, interception of interferon (IFN) signaling and inhibition of IFN-induced antiviral functions allow viruses to evade the host immune response and set up successful infections. Hepatitis C virus (HCV), the leading cause of chronic liver disease worldwide and a major public health hazard, causes persistent infection in the majority of infected individuals. IFN-based therapies, currently the only ones available for HCV infection, have been unable to eliminate viral infection in the majority of patients, and many studies suggest that HCV possesses mechanisms to antagonize the IFN-induced antiviral response. Multiple viral, host, and IFN-associated factors have been implicated in the interplay between HCV and IFN. Two viral proteins, NS5A and E2, became the focus of much attention and extensive study because of their abilities to inhibit IFN-induced, double-stranded RNA-activated protein kinase (PKR), a major mediator of the IFN-induced biologic response, and to perturb the IFN signaling pathway. In this review, we discuss the significance of the interferon sensitivity determining region (ISDR) within NS5A, which has been the subject of intense debates. In addition, we discuss the potential mechanisms by which NS5A interferes with IFN signaling and the current working models. Further understanding of the molecular mechanisms underlying the interaction between HCV and IFN will likely facilitate improvement of current IFN-based therapies and development of novel treatments for the HCV pandemic. Future HCV research will benefit from both the development of efficient, convenient model systems for viral propagation, and the utilization of high throughput, genomic-scale approaches.