Biliverdin inhibits hepatitis C virus nonstructural 3/4A protease activity: Mechanism for the antiviral effects of heme oxygenase?

Abstract

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 ribonucleic acid (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 (591 nm/622 nm) fluorescence energy transfer peptide, we found that both recombinant and endogenous nonstructural 3/4A (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 a median inhibitory concentration (IC 50 ) of 9 lM, similar to that of the commercial inhibitor, AnaSpec (Fremont, CA) #25346 (IC 50 5 lM). Lineweaver-Burk plots indicated mixed competitive and noncompetitive 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 greater than 80% silencing of BVR, inhibition of viral replication by BV was enhanced. BV also increased the antiviral activity of a-interferon in replicons. Conclusion: BV 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 in future drug therapies targeting the NS3/4A protease. (HEPATOLOGY 2010;52:1897-1905

Protective role of heme oxygenase-1 in liver

“…This clearly shows the antiviral role of HO-1 in hepatocytes (Zhu et al 2008). Our lab and others investigated the role of HO-1 products; carbon monoxide, iron and biliverdin on HCV replication (Hou et al 2009;Lehmann et al 2010;Zhu et al 2010). Interestingly, biliverdin seems to contribute to the antiviral activity of HO-1.…”

“…Biliverdin was shown to interfere with HCV replication, and specifically, by inhibiting HCV NS3/4A protease. Moreover, biliverdin exerts its effect by inducing the expression of antiviral interferons, such as interferon α2 and α17 (Lehmann et al 2010;Zhu et al 2010). It is clear that HO-1 products have inhibitory effect on HCV.…”

MicroRNA miR-24-3p Promotes Porcine Reproductive and Respiratory Syndrome Virus Replication through Suppression of Heme Oxygenase-1 Expression

“…Induction or overexpression of HO-1 also suppresses hepatitis C virus (HCV) replication and protects hepatocytes from oxidative damage (14). In addition, the HO-1 product biliverdin inhibits HCV replication by increasing the antiviral interferon response (51,52). Our previous work showed that HO-1 induction using different concentrations of CoPP greatly decreases both recombinant PRRSV and wild-type PRRSV replication in a dose-dependent manner.…”

Short Communication: Atazanavir-Based Therapy Is Associated with Higher Hepatitis C Viral Load in HIV Type 1-Infected Subjects with Untreated Hepatitis C

“…2 Likewise, Zhu et al recently demonstrated that BV has potent antiviral activity against HCV, with inhibitory action over HCV NS3/4A protease. 3 Iron has also been shown to inhibit HCV replication by preventing divalent caption binding to RdRp.…”

“…In vitro studies have reported that BR and BV show antiviral activity against HIV, the herpes virus, and HCV. 3 More specifically, the antiviral action against HCV is due to both recombinant and endogenous NS3/4A protease from replicon microsomes being inhibited by BR and BV.…”