A screen for novel hepatitis C virus RdRp inhibitor identifies a broad-spectrum antiviral compound

Abstract

Hepatitis C virus (HCV) is a global pathogen and infects more than 185 million individuals worldwide. Although recent development of direct acting antivirals (DAA) has shown promise in HCV therapy, there is an urgent need for the development of more affordable treatment options. We initiated this study to identify novel inhibitors of HCV through screening of compounds from the National Cancer Institute (NCI) diversity dataset. Using cell-based assays, we identified NSC-320218 as a potent inhibitor against HCV with an EC50 of 2.5 μM and CC50 of 75 μM. The compound inhibited RNA dependent RNA polymerase (RdRp) activity of all six major HCV genotypes indicating a pan-genotypic effect. Limited structure-function analysis suggested that the entire molecule is necessary for the observed antiviral activity. However, the compound failed to inhibit HCV NS5B activity in vitro, suggesting that it may not be directly acting on the NS5B protein but could be interacting with a host protein. Importantly, the antiviral compound also inhibited dengue virus and hepatitis E virus replication in hepatocytes. Thus, our study has identified a broad-spectrum antiviral therapeutic agent against multiple viral infections.

Hepatitis E Virus ORF2 Inhibits RIG-I Mediated Interferon Response

“…In order to identify the HEV protein(s) that might be interfering with the RIG-I signaling, a reporter assay was designed in which RIG-I mediated activation of the IFN-β promoter was quantified by measuring the activity of firefly luciferase, as described earlier (Madhvi et al, 2017). For this, all the known protein domains of HEV Genotype I (HEV-1) and Genotype III (HEV-3) were cloned into the mammalian expression vector pUNO-mcs.…”

Review on chemogenomic approaches towards hepatitis C viral targets

“…The combination of DAAs with older therapies (pegylated IFN and RBV) are used in a shorter duration of around 12 weeks and long‐term usage with IFN therapies increases the risk of side effects . Currently, other classes of non‐nucleoside inhibitors of RdRp are under development …”

In vitro methods for testing antiviral drugs

“…When available, viral genomes modified with reporter genes can be used for cell-based luminescent or fluorescent screening of viral inhibitors (Beadle et al, 2016;Edwards et al, 2015;Fenaux et al, 2016;Feng et al, 2014;Lo et al, 2017;Madhvi et al, 2017;Wang et al, 2015c). This approach can be extended to screen inhibitors of other enzymes.…”