Rationally derived inhibitors of hepatitis C virus (HCV) p7 channel activity reveal prospect for bimodal antiviral therapy.

Abigail Bloy,Jamel Mankouri,Stephen Griffin,Claire Scott,Rajendra Gosain,Sonia Abas,Andrew Macdonald,Monoj Mon Kalita,Jayakanth Kankanala,Mark Harris,Emma Brown,J.c Shaw ,David J Rowlands ,Barnabas King ,Toshana L Foster ,Matthew Bentham ,Dhani Ram Mahato ,Wolfgang B Fischer ,Alexander W Tarr ,Laura F Wetherill ,Richard Foster,Adel Samson

doi:10.7554/elife.52555

Abstract

Since the 1960s, a single class of agent has been licensed targeting virus-encoded ion channels, or 'viroporins', contrasting the success of channel blocking drugs in other areas of medicine. Although resistance arose to these prototypic adamantane inhibitors of the influenza A virus (IAV) M2 proton channel, a growing number of clinically and economically important viruses are now recognised to encode essential viroporins providing potential targets for modern drug discovery. We describe the first rationally designed viroporin inhibitor with a comprehensive structure-activity relationship (SAR). This step-change in understanding not only revealed a second biological function for the p7 viroporin from hepatitis C virus (HCV) during virus entry, but also enabled the synthesis of a labelled tool compound that retained biological activity. Hence, p7 inhibitors (p7i) represent a unique class of HCV antiviral targeting both the spread and establishment of infection, as well as a precedent for future viroporin-targeted drug discovery.

Highlights

Hepatitis C virus (HCV) represents a global clinical challenge as a major cause of chronic liver disease, with severe complications including cirrhosis, liver failure and primary liver cancers (hepatocellular- and intrahepatic cholangio- carcinomas (HCC, iCCA))
Refining a rapid throughput assay for secreted hepatitis C virus (HCV) infectivity p7 channel activity is essential for the secretion of infectious virions (Wozniak et al, 2010), making secreted infectivity an ideal biomarker readout for inhibitor antiviral effects
To expedite testing of secreted HCV infectivity following treatment with high numbers of compounds and/or concentration points, we adapted previously published protocols using the IncuCyte ZOOM (Stewart et al, 2015) to quantify infection of naıve cells immunostained for NS5A (Figure 1A)

Summary

Introduction

Hepatitis C virus (HCV) represents a global clinical challenge as a major cause of chronic liver disease, with severe complications including cirrhosis, liver failure and primary liver cancers (hepatocellular- and intrahepatic cholangio- carcinomas (HCC, iCCA)). Acute infection is predominantly asymptomatic which, combined with limited awareness and population screening, means that liver disease is often advanced upon diagnosis. WHO estimates put the total number of deaths due to HCV infection in 2015 at more than 400 000, with ~1.75 million new infections annually. HCV antiviral therapy, originally comprising recombinant type one interferon (IFN) combined with the guanosine analogue ribavirin, has been revolutionised by new direct-acting antivirals (DAA). DAA are an unprecedented drug development success, capable of achieving high rates of cure with favourable toxicity profiles enabling their use in patients with advanced disease

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Conclusion