Biliverdin Inhibits Hepatitis C Virus NS3/4A Protease Activity: Mechanism for the Antiviral Effects of Heme Oxygenase?

摘要

Induction of heme oxygenase -1 (HO-1) inhibits hepatitis C virus (HCV) replication. Of the products of the reaction catalyzed by HO-1 iron has been shown to inhibit HCV RNA polymerase, but little is known about the antiviral activity of biliverdin (BV). Herein, we report that BV inhibits viral replication and viral protein expression in a dose-dependent manner in replicons and cells harboring the infectious J6/JFH construct. Using the SensoLyte 620 HCV Protease Assay with a wide wavelength excitation/emission (591nm/622nm) fluorescence energy transfer peptide, we found that both recombinant and endogenous NS3/4A protease from replicon microsomes are potently inhibited by BV. Of the tetrapyrroles tested, BV was the strongest inhibitor of NS3/4A activity with an IC50 of 9 uM, similar to that of the commercial inhibitor, AnaSpec #25346 (IC50 5 uM). Lineweaver-Burk plots indicated mixed competitive and non-competitive inhibition of the protease by BV. In contrast, the effects of bilirubin (BR) on HCV replication and NS3/4A were much less potent. Because BV is rapidly converted to BR by biliverdin reductase (BVR) intracellularly, the effect of BVR knockdown on BV antiviral activity was assessed. After >80% silencing of BVR, inhibition of viral replication by BV was enhanced. BV also increased the antiviral activity of α-interferon in replicons.ConclusionBV is a potent inhibitor of HCV NS3/4A protease, which likely contributes to the antiviral activity of HO-1. These findings suggest that BV or its derivatives may be useful future drug therapies targeting the NS3/4A protease.