Antiviral suppression vs restoration of RIG-I signaling by hepatitis C protease and polymerase inhibitors

• Published in: Gastroenterology (New York, N.Y. 1943) Vol. 135; no. 5; p. 1710
• Main Authors: Liang, Yuqiong, Ishida, Hisashi, Lenz, Oliver, Lin, Tse-I, Nyanguile, Origène, Simmen, Kenny, Pyles, Richard B, Bourne, Nigel, Yi, Minkyung, Li, Kui, Lemon, Stanley M
• Format: Journal Article
• Language: English
• Published: United States 01.11.2008
• Subjects: Adaptor Proteins, Signal Transducing - biosynthesis; Adaptor Proteins, Signal Transducing - drug effects; Cell Line; DEAD Box Protein 58; DEAD-box RNA Helicases - biosynthesis; DEAD-box RNA Helicases - genetics; Genotype; Hepacivirus - enzymology; Hepacivirus - genetics; Hepatitis C, Chronic - drug therapy; Hepatitis C, Chronic - pathology; Hepatitis C, Chronic - virology; Hepatocytes - virology; Heterocyclic Compounds, 3-Ring - pharmacology; Humans; Immunoblotting; Interferon Regulatory Factor-3 - metabolism; Interferon-beta - drug effects; Interferon-beta - metabolism; Protease Inhibitors - pharmacology; Receptors, Immunologic; Signal Transduction; Simeprevir; Sulfonamides - pharmacology; Viral Nonstructural Proteins - antagonists & inhibitors; Viral Nonstructural Proteins - biosynthesis
• DOI: 10.1053/j.gastro.2008.07.023

Expression of the nonstructural protein (NS)3/4A protease in cells infected with hepatitis C virus (HCV) results in cleavage of the mitochondrial antiviral-signaling protein (MAVS) and disruption of signaling pathways that lead to viral activation of interferon regulatory factor 3 (IRF-3) and synthesis of type 1 interferons (IFN-alpha/beta). High concentrations of inhibitors of NS3/4A reverse this signaling defect, but quantitative analyses of this potential therapeutic effect are lacking. This study quantitatively assessed the rescue of IRF-3 signaling by NS3/4A inhibitors, compared with in vitro antiviral activity. Antiviral activities of 2 NS3/4A protease inhibitors (TMC435350 and an analog, TMC380765) and a nonnucleoside polymerase inhibitor (Tib-3) were determined in HCV replicon cells and in cells infected with genotype 1a and 2a viruses. The capacity to rescue IRF-3 activation in these cells was assessed by monitoring IFN-beta promoter activity following challenge with Sendai virus. Inhibitor-induced changes in NS3 and MAVS expression were assessed in immunoblots. Both protease inhibitors were capable of rescuing IFN-beta promoter activation but only at concentrations approximately 100-fold the antiviral 50% effective concentration (EC(50)) for genotype 1 virus. No rescue was observed with the polymerase inhibitor, even at a concentration 600-fold greater than the EC(50). IRF-3 activation did not correlate with reductions in NS3/4A levels or detection of full-length MAVS. Overexpression of the product of NS3/4A cleavage of MAVS did not result in a dominant-negative effect on signaling. NS3/4A protease inhibitors can restore IRF-3 signaling in HCV-infected cells but only at concentrations far in excess of the antiviral EC(50).