Identification of Type I and Type II Interferon-Induced Effectors Controlling Hepatitis C Virus Replication

Hepatology. 2012 Dec;56(6):2082-93. doi: 10.1002/hep.25908. Epub 2012 Oct 14.

Abstract

Persistent infection with hepatitis C virus (HCV) can lead to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. All current therapies of hepatitis C include interferon-alpha (IFN-α). Moreover, IFN-gamma (IFN-γ), the only type II IFN, strongly inhibits HCV replication in vitro and is the primary mediator of HCV-specific antiviral T-cell responses. However, for both cytokines the precise set of effector protein(s) responsible for replication inhibition is not known. The aim of this study was the identification of IFN-α and IFN-γ stimulated genes (ISGs) responsible for controlling HCV replication. We devised an RNA interference (RNAi)-based "gain of function" screen and identified, in addition to known ISGs earlier reported to suppress HCV replication, several new ones with proven antiviral activity. These include IFIT3 (IFN-induced protein with tetratricopeptide repeats 3), TRIM14 (tripartite motif containing 14), PLSCR1 (phospholipid scramblase 1), and NOS2 (nitric oxide synthase 2, inducible). All ISGs identified in this study were up-regulated both by IFN-α and IFN-γ, demonstrating a substantial overlap of HCV-specific effectors induced by either cytokine. Nevertheless, some ISGs were more specific for IFN-α or IFN-γ, which was most pronounced in case of PLSCR1 and NOS2 that were identified as main effectors of IFN-γ-mediated anti-HCV activity. Combinatorial knockdowns of ISGs suggest additive or synergistic effects demonstrating that with either IFN, inhibition of HCV replication is caused by the combined action of multiple ISGs.

Conclusion: Our study identifies a number of novel ISGs contributing to the suppression of HCV replication by type I and type II IFN. We demonstrate a substantial overlap of antiviral programs triggered by either cytokine and show that suppression of HCV replication is mediated by the concerted action of multiple effectors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antigens, Differentiation / genetics
  • Antigens, Differentiation / metabolism
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Gene Expression Regulation
  • Hepacivirus / physiology*
  • Hepatocytes / drug effects*
  • Hepatocytes / metabolism*
  • Humans
  • Interferon-alpha / pharmacology*
  • Interferon-gamma / pharmacology*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism
  • Phospholipid Transfer Proteins / genetics
  • Phospholipid Transfer Proteins / metabolism
  • RNA Interference
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism
  • Replicon
  • Tumor Cells, Cultured
  • Up-Regulation / drug effects
  • Virus Replication*

Substances

  • Antigens, Differentiation
  • Carrier Proteins
  • IFIT3 protein, human
  • IFITM3 protein, human
  • Interferon-alpha
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • PLSCR1 protein, human
  • Phospholipid Transfer Proteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • TRIM14 protein, human
  • leu-13 antigen
  • Interferon-gamma
  • NOS2 protein, human
  • Nitric Oxide Synthase Type II