New therapies in the management of hepatitis C virus

The influence of host factors and sequence variability of the p7 region on the response to pegylated interferon/ribavirin therapy for chronic hepatitis C genotype 1b in patients from Serbia

The goal of this study was to identify host and viral factors affecting the response to pegylated interferon/ribavirin (PEG-IFN/RBV) treatment in patients with chronic hepatitis C genotype 1b. Baseline characteristics of the patients and sequences within the p7 region were analyzed in pre-treatment serum samples from 53 individuals with chronic hepatitis C genotype 1b and related to the outcome of therapy. We found a significant correlation between age and response to therapy (p < 0.001). Furthermore, the pre-treatment viral load was closely associated with the stage of liver fibrosis (p < 0.001). The presence of fewer than 4 mutations and age above 40 were significantly associated with non-response (NR) (p < 0.001). Our findings may be useful for estimating the likelihood of achieving a sustained virologic response (SVR) in patients who are chronically infected with hepatitis C virus genotype 1b.

Evidence suggesting that HCV p7 protects E2 glycoprotein from premature degradation during virus production

The hepatitis C virus (HCV) genome encodes a 63 amino acid (aa) protein, p7, which is located between the structural and non-structural proteins. p7 localizes to endoplasmic reticulum membranes and is composed of two transmembrane domains (TM1 and TM2) and a cytoplasmic loop. While its exact role is unknown, p7 is crucial for assembly and/or release of infectious virus production in cell culture, as well as infectivity in chimpanzees. The contribution of p7 to the HCV life cycle may result from at least two distinct roles. Firstly, several studies have shown that p7 acts as an ion channel, the functionality of which is critical for infection. Secondly, p7 interacts with NS2 in a manner that may regulate the targeting of other structural proteins during the assembly process. In this study, we observed that mutations in TM1 and the cytoplasmic loop of p7 decreased infectious virus production in a single-cycle virus production assay. Analysis of intra- and extracellular virus titers indicated that p7 functions at a stage prior to generation of infectious particles. These effects were not due to altered RNA replication since no effects on levels of NS3 or NS5A protein were observed, and were not a consequence of altered recruitment of core protein to lipid droplets. Similarly, these mutations seemingly did not prevent nucleocapsid oligomerization. Importantly, we found that an alanine triplet substitution including the two basic residues of the cytoplasmic loop, which is integral to p7 ion channel function, significantly reduced E2 glycoprotein levels. A time course experiment tracking E2 levels indicated that E2 was degraded over time, as opposed to being synthesized in reduced quantities. The results of this study provide strong evidence that one of the functions of p7 is to protect HCV glycoproteins from premature degradation during virion morphogenesis.

Antiviral lectins from red and blue-green algae show potent in vitro and in vivo activity against hepatitis C virus

Hepatitis C virus (HCV) infection is a significant public health problem with over 170,000,000 chronic carriers and infection rates increasing worldwide. Chronic HCV infection is one of the leading causes of hepatocellular carcinoma which was estimated to result in ∼10,000 deaths in the United States in the year 2011. Current treatment options for HCV infection are limited to PEG-ylated interferon alpha (IFN-α), the nucleoside ribavirin and the recently approved HCV protease inhibitors telaprevir and boceprevir. Although showing significantly improved efficacy over the previous therapies, treatment with protease inhibitors has been shown to result in the rapid emergence of drug-resistant virus. Here we report the activity of two proteins, originally isolated from natural product extracts, which demonstrate low or sub-nanomolar in vitro activity against both genotype I and genotype II HCV. These proteins inhibit viral infectivity, binding to the HCV envelope glycoproteins E1 and E2 and block viral entry into human hepatocytes. In addition, we demonstrate that the most potent of these agents, the protein griffithsin, is readily bioavailable after subcutaneous injection and shows significant in vivo efficacy in reducing HCV viral titers in a mouse model system with engrafted human hepatocytes. These results indicate that HCV viral entry inhibitors can be an effective component of anti-HCV therapy and that these proteins should be studied further for their therapeutic potential.

Development and validation of the chronic hepatitis C virus treatment satisfaction (HCVTSat) instrument

BACKGROUND

While current medications used to treat patients with chronic hepatitis C virus (HCV) effectively produce sustained viral response (SVR), postponement of therapy is often times attributed to patient perceptions of unfavourable outcomes. However, an instrument to assess patient perceptions of therapy (i.e. treatment satisfaction) has not been developed.

AIM

To describe the development and validation the chronic Hepatitis C Virus Treatment Satisfaction (HCVTSat) instrument.

METHODS

Focus groups, expert review and cognitive debriefing were used to develop a draft 37-item instrument (scale: 1 = not important at all; 5 = extremely important). The preliminary instrument was administered to a pre-test sample of 145 patients through Mayo Clinic, Rochester, MN. A refined HCVTSat was administered to a main sample of 333 participants with a chronic HCV diagnosis through Harris Interactive.

RESULTS

The HCVTSat was completed by 333 participants with an average age of 51 (s.d. = 12.1) years, 55% male, current or previous HCV treatment experience, and a diagnosis of HCV for approximately 12 (s.d. = 8.9) years. Twelve items for the 3 dimensions, Treatment Experience (TE), Side Effects (SE) and Social Aspects (SA), were internally consistent (Cronbach's α range: 0.70-0.90), responsive and valid. Confirmatory factor analysis (goodness-of-fit indexes: χ(2) = 20.9, df = 23, P = 0.59; CFI = 1.00, GFI = 0.99, TFI = 1.00, RMSEA = 0.001) revealed a better fit with 9 items. All path coefficients were significant (P < 0.05). SE and SA were strong predictors of TE, while TE was positively associated with the 1-item global measure of TS (path coefficient = 0.12).

CONCLUSIONS

The 10-item HCVTSat demonstrated valid psychometric properties and assessed patient satisfaction with HCV therapies. However, additional studies are needed to validate the HCVTSat in conjunction with SVR and in patients in underrepresented populations.

Extended peginterferon plus ribavirin treatment for 72 weeks versus standard peginterferon plus ribavirin treatment for 48 weeks in chronic hepatitis C genotype 1 infected slow-responder adult patients

BACKGROUND

The standard length of peginterferon plus ribavirin treatment for chronic hepatitis C virus (HCV) genotype 1 infected patients is 48 weeks. However, the number of patients demonstrating a sustained virological response is not high. In order to improve sustained virological response, extending the length of the treatment period has been suggested.

OBJECTIVES

To study the benefits and harms of extended 72-week treatment in comparison with 48-week treatment with peginterferon plus ribavirin in patients with chronic HCV genotype 1 infection who have shown a slow antiviral response.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and LILACS until November 2011. We identified further trials by reviewing reference lists and contacting principal authors.

SELECTION CRITERIA

Trials were eligible for this review if they included patients infected with hepatitis C virus genotype 1 who had a slow antiviral response, and if those patients were randomised to completing 72 weeks versus 48 weeks of treatment with pegylated interferon and ribavirin.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the trials for risk of bias, and extracted the data. The primary outcomes were overall mortality, liver-related mortality, and liver-related morbidity. We extracted data separately according to two definitions of slow responders: 1) patients with ≥ 2 log viral reduction but still detectable HCV RNA after 12 weeks of treatment and undetectable HCV RNA after 24 weeks of treatment; 2) patients with detectable HCV RNA after four weeks of treatment. We calculated risk ratios from individual trials as well as in the meta-analyses of trials.

MAIN RESULTS

We included seven trials with 1369 participants. All trials had high risk of bias. Five trials used our first definition of slow responders, and three other trials (including one that used both definitions) used the second definition. None of the included trials mentioned our primary outcomes. However, regarding the secondary outcomes, extension of the treatment period to 72 weeks increased the sustained virological response according to both definitions (71/217 (32.7%) versus 52/194 (26.8%); risk ratio (RR) 1.43, 95% confidence interval (CI) 1.07 to 1.92, P = 0.02, I(2) = 8%; and 265/499 (53.1%) versus 207/496 (41.7%); RR 1.27, 95% CI 1.07 to 1.50, P = 0.006, I(2) = 38%), with a risk difference of 0.11 and calculated number needed to treat of nine. The end of treatment response was not significantly different between the two treatment groups. The number of participants who relapsed virologically was found to be lower in the groups that had been treated for 72 weeks using both definitions (27/84 (32.1%) versus 46/91 (50.5%); RR 0.59, 95% CI 0.40 to 0.86, P = 0.007, I(2) = 18%, 3 trials; and 85/350 (24.3%) versus 146/353 (41.4%); RR 0.59, 95% CI 0.47, 0.73, P < 0.000001, I(2) = 0%, 3 trials). The length of treatment did not significantly affect the adherence (247/279 (88.5%) versus 252/274 (92.0%); RR 0.95, 95% CI 0.84 to 1.07, P = 0.42, I(2) = 69%, 3 trials). In the single trial that reported adverse events, no significant difference was seen between the two treatment groups.

AUTHORS' CONCLUSIONS

This review demonstrates higher a proportion of sustained virological response after extension of treatment from 48 weeks to 72 weeks in HCV genotype 1 infected patients in whom HCV RNA was still detectable but decreased by ≥ 2 log after 12 weeks and became negative after 24 weeks of treatment, and in patients with detectable HCV RNA after four weeks of treatment with peginterferon plus ribavirin. The observed intervention effects can be caused by both systematic error (bias) and random errors (play of chance). There was no reporting on mortality and the reporting of clinical outcomes and adverse events was insufficient. More data are needed in order to recommend or reject the policy of extending the treatment period for slow responders.

Efficient palliative involved-field radiotherapy on highly progressive diffuse large B-cell primary gastric lymphoma with liver cirrhosis

We report the case of a 73-year-old woman having diffuse large B-cell primary gastric lymphoma with a cirrhotic liver caused by hepatitis C virus infection. She visited our hospital with symptoms of nausea and vomiting, which appeared to be caused by stenosis due to the tumor. Metastatic tumors were seen in the gastric and jugular lymph nodes. The clinical stage was IVB with a high risk of poor prognosis according to the international index. Because of poor hepatic reserve function, standard chemotherapy could not be administered. To maintain her quality of life, palliative involved-field radiotherapy was performed. The symptoms and tumor markers significantly improved, and computed tomography and endoscopy indicated the disappearance of the primary gastric tumor. Two months after radiotherapy and her return home, she died of pneumonia. Autopsy showed neither lymphoma cells nor stenosis of gastric lesion. The significant anti-tumor effect on primary tumor in our case suggests that the involved-field radiotherapy, although palliative, can be a therapeutic option for primary gastric lymphoma patients with various complications.

A genetic interaction between the core and NS3 proteins of hepatitis C virus is essential for production of infectious virus

By analogy to other members of the Flaviviridae family, the hepatitis C virus (HCV) core protein is presumed to oligomerize to form the viral nucleocapsid, which encloses the single-stranded RNA genome. Core protein is directed to lipid droplets (LDs) by domain 2 (D2) of the protein, and this process is critical for virus production. Domain 1 (D1) of core is also important for infectious particle morphogenesis, although its precise contribution to this process is poorly understood. In this study, we mutated amino acids 64 to 75 within D1 of core and examined the ability of these mutants to produce infectious virus. We found that residues 64 to 66 are critical for generation of infectious progeny, whereas 67 to 75 were dispensable for this process. Further investigation of the defective 64 to 66 mutant (termed JFH1(T)-64-66) revealed it to be incapable of producing infectious intracellular virions, suggesting a fault during HCV assembly. Furthermore, isopycnic gradient analyses revealed that JFH1(T)-64-66 assembled dense intracellular species of core, presumably representing nucleocapsids. Thus, amino acids 64 to 66 are seemingly not involved in core oligomerization/nucleocapsid assembly. Passaging of JFH1(T)-64-66 led to the emergence of a single compensatory mutation (K1302R) within the helicase domain of NS3 that completely rescued its ability to produce infectious virus. Importantly, the same NS3 mutation abrogated virus production in the context of wild-type core protein. Together, our results suggest that residues 64 to 66 of core D1 form a highly specific interaction with the NS3 helicase that is essential for the generation of infectious HCV particles at a stage downstream of nucleocapsid assembly.

Preparation of CHO cell-derived rhIFN-ω-Fc with improved pharmacokinetics

Interferon-omega (IFN-ω) may be a useful, promising and alternative antiviral agent, in addition to IFN-α-2a and IFN-α-2b. To improve the pharmacokinetics of IFN-ω for clinical use, the recombinant human IFN-ω-Fc fusion protein (rhIFN-ω-Fc) was expressed in a Chinese hamster ovary cell line (CHO-S), due to the longer serum half-life of rhIFN-ω-Fc compared to the native IFN-ω protein, and purified by affinity chromatography. Physicochemical characterization of the purified fusion protein was performed by SDS-PAGE electrophoresis, dot blot analysis and N-terminal amino acid sequence analysis. The results show that rhIFN-ω-Fc was highly expressed at the predicted size and with the N-terminal amino acid sequence. The antiviral activity was determined by the ability of IFNs to inhibit the cytopathic effects (CPEs) of vesicular stomatitis virus (VSV) on the human amnion WISH cells. The rhIFN-ω-Fc expressed in CHO-S cells has a specific activity of 1.6×10(7) IU/mg compared to rhIFN-ω expressed in yeast, which has a specific activity of 7×10(7) IU/mg. Equimolar concentrations of rhFN-ω and rhIFN-ω-Fc were administered to rabbits for pharmacokinetics comparison. The terminal half-life of rhIFN-ω-Fc was 35 times higher than that of rhIFN-ω. Thus, rhIFN-ω-Fc can be used as a prospective antiviral candidate especially for the treatment of chronic viral disease, such as hepatitis C virus (HCV) infection.