Recent advances in understanding hepatitis C

Long-chain fatty acyl-coenzyme A suppresses hepatitis C virus infection by targeting virion-bound lipoproteins

Hepatitis C virus (HCV) is a leading cause of chronic hepatitis and end-stage liver diseases. Mature HCV virions are bound by host-derived lipoproteins. Lack of an HCV vaccine warrants a major role of antiviral treatment in the global elimination of hepatitis C. Although direct-acting antivirals (DAAs) are replacing the interferon-based treatment and have dramatically improved the cure rate, the presence of viral variants resistant to DAAs, HCV genotype/subtype-specific efficacy, and high cost of DAAs argue novel and affordable regimens. In this study, we identified the antiviral effects of long-chain fatty acyl-coenzyme A (LCFA-CoA) against the infections of HCV genotypes 1-6 through targeting mature HCV-bound lipoproteins, suggesting novel mechanism(s) of antiviral different from those used by host-targeting agents or DAAs. We found that the antiviral activity of LCFA-CoA relied on the long-chain saturated fatty acid and the CoA group, and was enhanced when combined with pegylated-interferon or DAAs. Importantly, we demonstrated that LCFA-CoA efficiently inhibited the infection of HCV variants carrying DAA-resistant mutations. The mechanistic study revealed that LCFA-CoA specifically abolished the attachment and binding steps and also inhibited the cell-to-cell viral transmission. LCFA-CoA targeted mature HCV-bound lipoproteins, but not apolipoproteins B or E. In addition, LCFA-CoA could also inhibit the infection of the dengue virus. Our findings suggest that LCFA-CoA could potentially serve as a supplement HCV therapy, particularly for the DAA-resistant HCV variants. Taken together, LCFA-CoA may be further developed to be a novel class of antivirals with mechanism(s), different from host-targeting agents or DAAs, of targeting the components associated with mature HCV virions.

The circadian clock components BMAL1 and REV-ERBα regulate flavivirus replication

The circadian clock regulates immune responses to microbes and affects pathogen replication, but the underlying molecular mechanisms are not well understood. Here we demonstrate that the circadian components BMAL1 and REV-ERBα influence several steps in the hepatitis C virus (HCV) life cycle, including particle entry into hepatocytes and RNA genome replication. Genetic knock out of Bmal1 and over-expression or activation of REV-ERB with synthetic agonists inhibits the replication of HCV and the related flaviruses dengue and Zika via perturbation of lipid signaling pathways. This study highlights a role for the circadian clock component REV-ERBα in regulating flavivirus replication.

Risk factors for familial clustering of hepatitis C virus infection in a Chinese Han population: a cross-sectional study

Background

Hepatitis C is a curable disease, but reinfection from household contact may occur in patients who have achieved sustained viral response (SVR).

Methods

A total of 997 ethnic Han HCV treatment-naïve adult patients were enrolled in a cross-sectional study with stratified sampling based on the populations of five geographic regions across China to examine the genetic and physiological parameters associated with the phenomenon of HCV familial clustering.

Results

Of the total 997 patients, there were 59 patients who had at least one family member with HCV infection according to patient self-report. Comparison between patients with and without HCV familial clustering by univariate regression analysis showed that genotype 2, sexual transmission, long-term exposure to HCV patients, monthly family income per person less than 2000 yuan, farming occupation, and the southern and northern regions were associated with HCV familial clustering. Blood transfusion was negatively associated with HCV familial clustering. Multivariate logistic regression analysis suggested that long-term exposure to HCV patients and low family income were correlated with HCV familial clustering, whereas blood transfusion was negatively associated, which meant that blood transfusion was not the main transmission route in HCV familial clustering.

Conclusion

Long-term exposure to HCV patients and low family income were correlated with HCV familial clustering, whereas blood transfusion was not the main transmission route in HCV familial clustering. To reduce reinfection from household contacts, education and awareness of HCV transmission routes and familial clustering should be strengthened, especially among HCV patients’ family members, low-income families and non-blood transmission hepatitis C patients.

Characterization of Hepatitis C Virus IRES Quasispecies - From the Individual to the Pool

Hepatitis C virus (HCV) is a single-stranded positive-sense RNA virus from the genus Hepacivirus. The viral genomic +RNA is 9.6 kb long and contains highly structured 5′ and 3′ untranslated regions (UTRs) and codes for a single large polyprotein, which is co- and post-translationally processed by viral and cellular proteases into at least 11 different polypeptides. Most of the 5′ UTR and an initial part of the polyprotein gene are occupied by an internal ribosome entry site (IRES), which mediates cap-independent translation of the viral proteins and allows the virus to overcome cellular antiviral defense based on the overall reduction of the cap-dependent translation initiation. We reconsidered published results concerning a search for possible correlation between patient response to interferon-based antiviral therapy and accumulation of nucleotide changes within the HCV IRES. However, we were unable to identify any such correlation. Rather than searching for individual mutations, we suggest to focus on determination of individual and collective activities of the HCV IRESs found in patient specimens. We developed a combined, fast, and undemanding approach based on high-throughput cloning of the HCV IRES species to a bicistronic plasmid followed by determination of the HCV IRES activity by flow cytometry. This approach can be adjusted for measurement of the individual HCV IRES activity and for estimation of the aggregate ability of the whole HCV population present in the specimen to synthesize viral proteins. To detect nucleotide variations in the individual IRESs, we used denaturing gradient gel electrophoresis (DGGE) analysis that greatly improved identification and classification of HCV IRES variants in the sample. We suggest that determination of the collective activity of the majority of HCV IRES variants present in one patient specimen in a given time represents possible functional relations among variant sequences within the complex population of viral quasispecies better than bare information about their nucleotide sequences. A similar approach might be used for monitoring of sequence variations in quasispecies populations of other RNA viruses in all cases when changes in primary sequence represent changes in measurable and easily quantifiable phenotypes.

Role of interferon-stimulated genes in regulation of HCV infection and type I interferon anti-HCV activity

HCV chronically infects over 71 million people worldwide and is one of the leading causes of advanced liver diseases. Type I interferons (IFN-α/β) play critical role in host antiviral innate immunity. IFN-α/β exerts its anti-HCV effects through the activation of the JAK/STAT signaling pathway leading to the induction of a few hundred interferon-stimulated genes (ISGs). The interplay between ISG and HCV infection remains partially understood. In this review, we summarized the role of ISGs in HCV infection and interferon anti-HCV activity.

Phosphorylated AKT expression in tumor-adjacent normal tissue is associated with poor prognosis in patients with hepatocellular carcinoma

The AKT pathway serves important roles in tumor cell growth. Its overexpression is associated with poor prognosis in a number of types of cancer; however, the role of AKT in the role of the pathogenesis of hepatocellular carcinoma (HCC) remains unclear. The present study was undertaken to explore the clinical relevance of phosphorylated AKT (p-AKT) in HCC. The level of p-AKT in tumor (TU) and paired adjacent normal liver (AN) tissue from 202 HCC patients was evaluated with immunohistochemistry. The results demonstrated that p-AKT was more highly expressed in TU than in AN tissue. Kaplan-Meier curves and Cox regression revealed that patients with a high expression of p-AKT (AN) exhibited reduced overall and relapse-free survival times; this was not observed at a statistically significant level in p-AKT (TU). Additionally, the high expression of p-AKT (AN) was positively correlated with hepatitis C virus (HCV) infection in HCC patients. These results support the hypothesis that AKT activation is a mechanism of HCV-induced hepatocarcinogenesis, suggesting that AKT can be a therapeutic target for the treatment of recurrent HCC subsequent to surgical resection.

(-)-Epigallocatechin-3-gallate enhances poly I:C-induced interferon-λ1 production and inhibits hepatitis C virus replication in hepatocytes

AIM

To investigate the effect of (-)-epigallocatechin-3-gallate (EGCG) on polyinosinic-polycytidylic acid (poly I:C)-triggered intracellular innate immunity against hepatitis C virus (HCV) in hepatocytes.

METHODS

A cell culture model of HCV infection was generated by infecting a hepatoma cell line, Huh7, with HCV JFH-1 strain (JFH-1-Huh7). Poly I:C with a high molecular weight and EGCG were used to stimulate the JFH-1-Huh7 cells. Real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of intracellular mRNAs and of intracellular and extracellular HCV RNA. Enzyme-linked immunosorbent assay was used to evaluate the interferon (IFN)-λ1 protein level in the cell culture supernatant. Immunostaining was used to examine HCV core protein expression in Huh7 cells.

RESULTS

Our recent study showed that HCV replication could impair poly I:C-triggered intracellular innate immune responses in hepatocytes. In the current study, we showed that EGCG treatment significantly increased the poly I:C-induced expression of Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I, and IFN-λ1 in JFH-1-Huh7 cells. In addition, supplementation with EGCG increased the poly I:C-mediated antiviral activity in JFH-1-Huh7 cells at the intracellular and extracellular HCV RNA and protein levels. Further investigation of the mechanisms showed that EGCG treatment significantly enhanced the poly I:C-induced expression of IFN-regulatory factor 9 and several antiviral IFN-stimulated genes, including ISG15, ISG56, myxovirus resistance A, and 2'-5'-oligoadenylate synthetase 1, which encode the key antiviral elements in the IFN signaling pathway.

CONCLUSION

Our observations provide experimental evidence that EGCG has the ability to enhance poly I:C-induced intracellular antiviral innate immunity against HCV replication in hepatocytes.

Correlation of Serum Soluble Fibrinogen-Like Protein 2 with Soluble FAS Ligand and Interferon Gamma in Egyptian Hepatitis C Virus-Infected Patients and Hepatocellular Carcinoma Patients

Infection with hepatitis C virus (HCV) remains one of the serious human diseases worldwide, especially in Egypt, which can lead to cirrhosis or hepatocellular carcinoma (HCC). However, the exact molecular mechanism of HCC progress in HCV-infected patients remains unclear. Soluble fibrinogen-like protein 2 (sFGL2) is a modulator of the immune response that is secreted by T cells and inhibits maturation of dendritic cells and T cell proliferation. In the current study, serum sFGL2 levels were analyzed by enzyme-linked immunosorbent assay (ELISA) technique in 30 chronic HCV-infected patients (HCV group), 30 chronic HCV-infected patients with HCC (HCC group), and 12 healthy individuals (control group). Moreover, serum levels of soluble FAS ligand (sFASL) and interferon gamma (IFN-γ) were analyzed and correlated with sFGL2 levels. According to our results, serum sFGL2 levels were significantly elevated in all patients with chronic HCV infection. However, HCC patients showed lower sFGL2 levels than HCV-infected patients without HCC incidence. In addition, serum sFASL levels were significantly elevated in both HCV and HCC groups, whereas serum IFN-γ levels were only elevated in the HCC group. Interestingly, sFGL2 correlated positively with serum total bilirubin level and negatively with serum levels of sFASL, IFN-γ, and albumin in HCV and HCC groups. Thus, conclusively, sFGL2 level increases in Egyptian HCV-infected and HCC patients. Taken together, the current work may open future possibility of designing new treatment strategies for HCV infection targeting sFGL2 and its immunosuppressive effect.

The Role of Type III Interferons in Hepatitis C Virus Infection and Therapy

The human interferon (IFN) response is a key innate immune mechanism to fight virus infection. IFNs are host-encoded secreted proteins, which induce IFN-stimulated genes (ISGs) with antiviral properties. Among the three classes of IFNs, type III IFNs, also called IFN lambdas (IFNLs), are an essential component of the innate immune response to hepatitis C virus (HCV). In particular, human polymorphisms in IFNL gene loci correlate with hepatitis C disease progression and with treatment response. To date, the underlying mechanisms remain mostly elusive; however it seems clear that viral infection of the liver induces IFNL responses. As IFNL receptors show a more restricted tissue expression than receptors for other classes of IFNs, IFNL treatment has reduced side effects compared to the classical type I IFN treatment. In HCV therapy, however, IFNL will likely not play an important role as highly effective direct acting antivirals (DAA) exist. Here, we will review our current knowledge on IFNL gene expression, protein properties, signaling, ISG induction, and its implications on HCV infection and treatment. Finally, we will discuss the lessons learnt from the HCV and IFNL field for virus infections beyond hepatitis C.

Charge neutralization as the major factor for the assembly of nucleocapsid-like particles from C-terminal truncated hepatitis C virus core protein

BACKGROUND

Hepatitis C virus (HCV) core protein, in addition to its structural role to form the nucleocapsid assembly, plays a critical role in HCV pathogenesis by interfering in several cellular processes, including microRNA and mRNA homeostasis. The C-terminal truncated HCV core protein (C124) is intrinsically unstructured in solution and is able to interact with unspecific nucleic acids, in the micromolar range, and to assemble into nucleocapsid-like particles (NLPs) in vitro. The specificity and propensity of C124 to the assembly and its implications on HCV pathogenesis are not well understood.

METHODS

Spectroscopic techniques, transmission electron microscopy and calorimetry were used to better understand the propensity of C124 to fold or to multimerize into NLPs when subjected to different conditions or in the presence of unspecific nucleic acids of equivalent size to cellular microRNAs.

RESULTS

The structural analysis indicated that C124 has low propensity to self-folding. On the other hand, for the first time, we show that C124, in the absence of nucleic acids, multimerizes into empty NLPs when subjected to a pH close to its isoelectric point (pH ≈ 12), indicating that assembly is mainly driven by charge neutralization. Isothermal calorimetry data showed that the assembly of NLPs promoted by nucleic acids is enthalpy driven. Additionally, data obtained from fluorescence correlation spectroscopy show that C124, in nanomolar range, was able to interact and to sequester a large number of short unspecific nucleic acids into NLPs.

DISCUSSION

Together, our data showed that the charge neutralization is the major factor for the nucleocapsid-like particles assembly from C-terminal truncated HCV core protein. This finding suggests that HCV core protein may physically interact with unspecific cellular polyanions, which may correspond to microRNAs and mRNAs in a host cell infected by HCV, triggering their confinement into infectious particles.

Elbasvir/Grazoprevir: A Review of the Latest Agent in the Fight against Hepatitis C

Hepatitis C virus (HCV) is estimated to affect up to 150 million people worldwide. Despite worldwide prevalence, treatment modalities prior to 2011 remained suboptimal, with low virologic response rates and intolerable side effect profiles. Fortunately, the landscape of treatment for chronic hepatitis C has rapidly evolved since the introduction of HCV NS3/4 protease inhibitors in 2011. Elbasvir, a NS5A inhibitor, combined with grazoprevir, a NS3/4A protease inhibitor, is the latest FDA-approved therapy for patients with genotype 1 or 4 chronic hepatitis C, with or without compensated cirrhosis. This review will focus on the current literature and clinical evidence supporting elbasvir/grazoprevir as first-line therapy in patients with genotypes 1 and 4 chronic hepatitis C.

Hydroxychloroquine augments early virological response to pegylated interferon plus ribavirin in genotype-4 chronic hepatitis C patients

The therapeutic effect of pegylated interferon (peg-IFN) alfa-2a combined with ribavirin (RBV) on chronic hepatitis C Egyptian patients is low and further efforts are required to optimize this therapy for achievement of higher rates of virological response. This study aimed to evaluate the safety and efficacy of hydroxychloroquine (HCQ) in combination with pegylated interferon plus ribavirin on early virological response (EVR) in chronic hepatitis C Egyptian patients. Naïve 120 Egyptian patients with chronic hepatitis C virus infection were divided into two groups. Group 1 have administered the standard of care therapy (pegylated interferon alfa-2a plus ribavirin) for 12 weeks, (n = 60). Group 2 have administered hydroxychloroquine plus standard of care therapy for 12 weeks, (n = 60). Therapeutics included hydroxychloroquine (200 mg) oral twice daily, peginterferon alfa-2a (160 μg) subcutaneous once weekly and oral weight-based ribavirin (1000-1200 mg/day). Baseline characteristics were similar in the two groups. The percentage of early virological response was significantly more in patients given the triple therapy than in patients given the standard of care [54/60 (90%) vs. 43/60 (71.7%); P = 0.011; respectively]. Biochemical response at week 12 was also significantly higher in patients given the triple therapy compared with the standard of care [58/60 (96.7%) vs. 42/60 (70%); P < 0.001; respectively]. Along the study, the observed adverse events were mild and similar across treatment groups. Addition of hydroxychloroquine to pegylated interferon plus ribavirin improves the rate of early virological and biochemical responses in chronic hepatitis C Egyptian patients without an increase in adverse events. J. Med. Virol. 88:2170-2178, 2016. © 2016 Wiley Periodicals, Inc.