Am J Pathol. 2014 Jan;184(1):214-29.

HCV infection selectively impairs type I but not type III IFN signaling.

  • 1Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
  • 2Biogen Idec, Inc., Cambridge, Massachusetts.
  • 3Department of Gastroenterology and Hepatology, Tulane University School of Medicine, New Orleans, Louisiana.
  • 4Department of Biochemistry, Tulane University School of Medicine, New Orleans, Louisiana.
  • 5Department of Medicine and Pathology, University of Utah School of Medicine, Salt Lake City, Utah.
  • 6Department of Animal Biology, University of Pennsylvania, Philadelphia, Pennsylvania.
  • 7Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana. Electronic address:



A stable and persistent Hepatitis C virus (HCV) replication cell culture model was developed to examine clearance of viral replication during long-term treatment using interferon-α (IFN-α), IFN-λ, and ribavirin (RBV). Persistently HCV-infected cell culture exhibited an impaired antiviral response to IFN-α+RBV combination treatment, whereas IFN-λ treatment produced a strong and sustained antiviral response that cleared HCV replication. HCV replication in persistently infected cells induced chronic endoplasmic reticulum (ER) stress and an autophagy response that selectively down-regulated the functional IFN-α receptor-1 chain of type I, but not type II (IFN-γ) or type III (IFN-λ) IFN receptors. Down-regulation of IFN-α receptor-1 resulted in defective JAK-STAT signaling, impaired STAT phosphorylation, and impaired nuclear translocation of STAT. Furthermore, HCV replication impaired RBV uptake, because of reduced expression of the nucleoside transporters ENT1 and CNT1. Silencing ER stress and the autophagy response using chemical inhibitors or siRNA additively inhibited HCV replication and induced viral clearance by the IFN-α+RBV combination treatment. These results indicate that HCV induces ER stress and that the autophagy response selectively impairs type I (but not type III) IFN signaling, which explains why IFN-λ (but not IFN-α) produced a sustained antiviral response against HCV. The results also indicate that inhibition of ER stress and of the autophagy response overcomes IFN-α+RBV resistance mechanisms associated with HCV infection.

Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc.

PMID: 24215913



Hepatitis C virus (HCV) infection is associated with high rate of chronic liver disease, liver cirrhosis and hepatocellular carcinoma. It is a significant public health problem worldwide (1). The standard treatment option for chronic HCV infection is the combination therapy including interferon-alpha, ribavirin along with either a protease or polymerase inhibitor. This new therapy has improved the sustained virological response rate of chronic HCV infection. However, this combination therapy has not improved the SVR rate among patients who are initially non-responsive to peginterferon-alpha and ribavirin (2). Also peginterferon-alpha plus ribavirin dual therapy still remains a treatment option for patients with chronic HCV infections in many parts of the world. Studies conducted over the years indicate that a number of viral and host related factors contribute to the interferon-alpha and RBV treatment response in HCV infection (3,4). High viral-load and certain HCV genotype are some of the viral related risk factors implicated for non-responsive to interferon-alpha and RBV (4). Host related factors important to interferon-alpha and RBV sensitivity is the IFN-lambda (Type III IFN) genotype (5-7). Many clinical studies all over the world have confirmed these associations among chronic HCV patients who have received IFN-alpha and RBV treatment. However, the mechanisms how the viral and host related factors could play a role in the interferon-alpha and RBV treatment outcome is unknown.

We set out to perform this basic research to address the mechanisms of how the viral and host related factors play a role in IFN-alpha and RBV sensitivity and how IFN-lambda genetic is important for HCV clearance. We have developed a long-term and stable infection system in a hepatoma cell line where the mechanisms of HCV clearance in the presence of IFN-alpha, IFN-lambda and RBV can be studied in a quantitative manner.

This model allowed us to verify the impact of high level HCV replication and host cell response to antiviral therapy. In this we concluded that IFN-alpha and RBV combination treatment inhibit HCV replication but this combination treatment was unable to clear the HCV infection. Interferon-lambda, which is a Type III IFN discovered very recently, induces HCV clearance in the persistently infected culture. We have found that long-term HCV replication in a hepatoma cell line developed a chronic stress condition in endoplasmic reticulum (ER) and induced autophagy response (8). Using a flow sorting method we verified that a fraction of HCV infected hepatoma cells that remained insensitive to interferon-alpha and RBV treatment due to impaired cell surface expression of IFN-alpha receptor. We showed in this report that HCV induced autophagy (lysosomal degradation) selectively degrades the cell surface expression of IFNAR1 chain of the Type I IFN-receptor. The virus induced autophagy response also degrades the nucleoside transporter ENT1 required for RBV uptake into the hepatocytes. These findings provide a potential mechanism why HCV replication cannot be cured by either IFN-alpha or RBV treatment even combination of both. However, HCV induced autophagy response has no effect on the cell surface expression of IFN-lambda receptors, therefore, IFN-lambda (IL-29) induced HCV clearance in the persistently infected HCV cell culture.

The most striking finding in this study was how the HCV induced cellular autophagy response impairs IFN-alpha and RBV antiviral response (Figure 1). These results could possibly explain the reason why some chronic HCV patients with a high viral load do not respond to IFN-alpha and RBV therapy. The other important finding is that the mechanisms of HCV clearance relates to the IFN-lambda. These results also now explain the clinical association of certain IL-28B genotype with HCV clearance by IFN-alpha and RBV antiviral therapy. Our study results indicate that IFN-λ can be an alternative choice for patients whose who are non-responsive to IFN-α.

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Acknowledgements: This work was supported from NIH grant CA127481, CA089121, AI103106

Address of Correspondence:

Srikanta Dash, Ph.D., Department of Pathology and Laboratory Medicine, Tulane University Health Sciences Center,1430 Tulane Avenue, New Orleans, LA-70112. Tel: 504-988-2519; Fax: 504-988-7389. Email:


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