Search

Chronic hepatitis B and D infections are major causes of liver disease and hepatocellular carcinoma worldwide. Efficient therapeutic approaches for cure are absent. Sharing the same envelope proteins, hepatitis B virus and hepatitis delta virus use the sodium/taurocholate cotransporting polypeptide (a bile acid transporter) as a receptor to enter hepatocytes. However, the detailed mechanisms of the viral entry process are still poorly understood. Here, we established a high-throughput infectious cell culture model enabling functional genomics of hepatitis delta virus entry and infection. Using a targeted RNA interference entry screen, we identified glypican 5 as a common host cell entry factor for hepatitis B and delta viruses. Conclusion: These findings advance our understanding of virus cell entry and open new avenues for curative therapies. As glypicans have been shown to play a role in the control of cell division and growth regulation, virus–glypican 5 interactions may also play a role in the pathogenesis of virus-induced liver disease and cancer. (Hepatology 2016;63:35–48)

Recurrent hepatitis C virus (HCV) infection after liver transplantation (LT) is associated with accelerated progression of liver disease, frequently leading to graft loss and early death. Existing treatment options for severe recurrent HCV infection are limited by suboptimal efficacy, poor tolerability, and numerous drug interactions. We provided sofosbuvir (SOF) and ribavirin (RBV) on a compassionate-use basis to patients with severe recurrent hepatitis C, including those with fibrosing cholestatic hepatitis (FCH) and decompensated cirrhosis who had a life expectancy of 1 year or less. All patients were to receive 24-48 weeks of SOF plus RBV. Investigators could add pegylated interferon to the regimen at their discretion. Data from the first 104 patients who completed or prematurely discontinued treatment by January 1, 2014 are presented. Of the 104 patients analyzed, 52 had an early severe recurrence (diagnosed 12 months after LT). Twelve patients who underwent retransplantation were excluded from our efficacy analysis. Of the 92 patients assessed, 54 (59%) achieved sustained virological response (SVR) at 12 weeks after the end of treatment, with a higher rate (73%; 35 of 48) in patients with early severe recurrence. Of the 103 patients assessed for clinical outcome, 59 (57%) reported clinical improvement at the last study visit, 23 (22%) were unchanged, 3 (3%) had a worsened clinical status, and 13 (13%) died. Overall, 123 serious adverse events (SAEs) occurred in 49 patients (47%). SAEs associated with hepatic decompensation were the most frequent, with 26 SAEs occurring in 19 patients (18%). Conclusion: SOF and RBV provide high rates of SVR in patients with severe recurrent HCV, including patients with early severe recurrence, FCH, and cirrhosis. (Hepatology 2015;61:1485-1494)

Interferon-alpha (IFN-alpha) exhibits its antiviral activity through signal transducer and activator of transcription protein (STAT) signaling and the expression of IFN response genes (IRGs). Viral infection has been shown to result in activation of epidermal growth factor receptor (EGFR)-a host cell entry factor used by several viruses, including hepatitis C virus. However, the effect of EGFR activation for cellular antiviral responses is unknown. Here, we uncover cross-talk between EGFR and IFN-alpha signaling that has a therapeutic effect on IFN-alpha-based therapies and functional relevance for viral evasion and IFN resistance. We show that combining IFN-alpha with the EGFR inhibitor, erlotinib, potentiates the antiviral effect of each compound in a highly synergistic manner. The extent of the synergy correlated with reduced STAT3 phosphorylation in the presence of erlotinib, whereas STAT1 phosphorylation was not affected. Furthermore, reduced STAT3 phosphorylation correlated with enhanced expression of suppressors of cytokine signaling 3 (SOCS3) in the presence of erlotinib and enhanced expression of the IRGs, radical S-adenosyl methionine domain containing 2 and myxovirus resistance protein 1. Moreover, EGFR stimulation reduced STAT1 dimerization, but not phosphorylation, indicating that EGFR cross-talk with IFN signaling acts on the STATs at the level of binding DNA. Conclusions: Our results support a model where inhibition of EGFR signaling impairs STAT3 phosphorylation, leading to enhanced IRG expression and antiviral activity. These data uncover a novel role of EGFR signaling in the antiviral activity of IFN-alpha and open new avenues of improving the efficacy of IFN-alpha-based antiviral therapies.

Using a new bioinformatic method to analyze ribosome profiling data, we show that 40% of lncRNAs and pseudogene RNAs expressed in human cells are translated. In addition, ~35% of mRNA coding genes are translated upstream of the primary protein-coding region (uORFs) and 4% are translated downstream (dORFs). Translated lncRNAs preferentially localize in the cytoplasm, whereas untranslated lncRNAs preferentially localize in the nucleus. The translation efficiency of cytoplasmic lncRNAs is nearly comparable to that of mRNAs, suggesting that cytoplasmic lncRNAs are engaged by the ribosome and translated. While most peptides generated from lncRNAs may be highly unstable byproducts without function, ~9% of the peptides are conserved in ORFs in mouse transcripts, as are 74% of pseudogene peptides, 24% of uORF peptides and 32% of dORF peptides. Analyses of synonymous and nonsynonymous substitution rates of these conserved peptides show that some are under stabilizing selection, suggesting potential functional importance.

Understanding the immunological correlates associated with protective immunity following hepatitis C virus (HCV) reexposure is a prerequisite for the design of effective HCV vaccines and immunotherapeutics. In this study we performed a comprehensive analysis of innate and adaptive immunity following HCV reexposure of two chimpanzees that had previously recovered from HCV-JFH1 infection. One of the chimpanzees, CH10274, became protected from active viremia by repeated challenges with homologous HCV-JFH1 and developed neutralizing antibodies, but was later infected with high-level viremia by a heterologous challenge with the HCV H77 virus that persisted for more than 1 year. The other chimpanzee, CH10273, was protected from a similar, heterologous H77 challenge without any evidence of neutralizing antibodies. Peripheral HCV-specific T-cell responses were present in both chimpanzees after challenges and, interestingly, the overall magnitude of response was lower in uninfected CH10273, which, however, exhibited a more robust CD8+ T-cell response. CH10273 showed higher hepatic expression of CD8 and CD56 (natural killer) markers than CH10274 did shortly after inoculation with H77. The heightened T-cell response was associated with an enhanced hepatic production of interferons (both type I and II) and interferon-stimulated genes (ISGs) in CH10273. Therefore, protection or clearance of HCV reinfection upon heterologous rechallenge depends on the activation of both intrahepatic innate and cellular immune responses. Furthermore, our results suggest that serum neutralizing antibodies may contribute to early control of viral replication and spread after homologous HCV rechallenges but may not be sufficient for a long-term protective immunity. Conclusion: Our study shows that protective immunity against HCV reinfection is orchestrated by a complex network of innate and adaptive immune responses. (HEPATOLOGY 2011;)

With an estimated 170 million infected individuals, hepatitis C virus (HCV) has a major impact on public health. A vaccine protecting against HCV infection is not available, and current antiviral therapies are characterized by limited efficacy, high costs, and substantial side effects. Binding of the virus to the cell surface followed by viral entry is the first step in a cascade of interactions between virus and the target cell that is required for the initiation of infection. Because this step represents a critical determinant of tissue tropism and pathogenesis, it is a major target for host cell responses such as antibody-mediated virus-neutralization-and a promising target for new antiviral therapy. The recent development of novel tissue culture model systems for the study of the first steps of HCV infection has allowed rapid progress in the understanding of the molecular mechanisms of HCV binding and entry. This review summarizes the impact of recently identified viral and host cell factors for HCV attachment and entry. Clinical implications of this important process for the pathogenesis of HCV infection and novel therapeutic interventions are discussed.

International audience