Abstract
Ledipasvir, a direct acting antiviral agent (DAA) targeting the Hepatitis C Virus NS5A protein, exhibits picomolar activity in replicon cells. While its mechanism of action is unclear, mutations that confer resistance to ledipasvir in HCV replicon cells are located in NS5A, suggesting that NS5A is the direct target of ledipasvir. To date co-precipitation and cross-linking experiments in replicon or NS5A transfected cells have not conclusively shown a direct, specific interaction between NS5A and ledipasvir. Using recombinant, full length NS5A, we show that ledipasvir binds directly, with high affinity and specificity, to NS5A. Ledipasvir binding to recombinant NS5A is saturable with a dissociation constant in the low nanomolar range. A mutant form of NS5A (Y93H) that confers resistance to ledipasvir shows diminished binding to ledipasvir. The current study shows that ledipasvir inhibits NS5A through direct binding and that resistance to ledipasvir is the result of a reduction in binding affinity to NS5A mutants.
Highlights
Hepatitis C Virus (HCV) infection is a leading cause of liver disease and hepatic cancer
While drug-associated resistance mutations have been identified in NS5A-domain 1, direct evidence of an interaction between this class of direct acting antiviral (DAA) and NS5A has been elusive
We have developed an in vitro binding assay that directly measures LDV binding to NS5A
Summary
Hepatitis C Virus (HCV) infection is a leading cause of liver disease and hepatic cancer. An estimated 170 million individuals worldwide are infected with HCV [1]. The HCV genome encodes a polyprotein of ~3000 amino acids. The polyprotein is proteolytically cleaved by host and viral proteases to yield 10 proteins (3 structural proteins: core, E1, E2 and 7 non-structural proteins: p7, NS2, NS3, NS4A, NS4B, NS5A, NS5B) that are responsible for viral replication and assembly [2]. NS3-5B form a membrane associated complex that is responsible for replication of the HCV genome. Several direct acting antiviral (DAA) agents have been approved for use in patients with HCV, including the NS3/NS4A protease inhibitors telaprevir, boceprevir, and simeprevir and the NS5B polymerase inhibitor sofosbuvir [3]. Treatment of patients with NS5A DAAs results in a rapid decline of viral load levels and it has been
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
