NS5A inhibitors 

Non-structural protein 5A (NS5A) inhibitors are a direct-acting antiviral agent used to treat hepatitis C virus (HCV). The NS5A protein has a substantial role in viral replication, packaging, assembly and complex interactions with cellular functions. Therefore NS5A inhibitors treat viral infections by reducing the ability of the virus to replicate. NS5A inhibitors may be used to treat specific HCV genotypes and are often used in conjunction with other antiviral agents.

Nonstructural protein 5A (NS5A) inhibitors are direct acting antiviral agents (DAAs) that target viral proteins, and their development was a culmination of increased understanding of the viral life cycle combined with advances in drug discovery technology.

2013 – The first NS5B polymerase inhibitor sofosbuvir approved. Dasabuvir was approved in 2014. 2014 – The first NS5A inhibitor ledipasvir was approved. Four other NS5A inhibitors of this class—daclatasvir, ombitasvir, elbasvir and velpatasvir—have been subsequently approved.

The hepatitis C virus (HCV) non-structural 5A (NS5A) protein has generated wide interest in HCV research because of its ability to modulate the host cell interferon (IFN) response. The protein is phosphorylated on multiple sites by host cell kinases and interacts with host cell membranes.

NS5A and NS5B are essential for viral RNA replication and production of infectious particles. While the structure and function of NS5B, the viral RNA polymerase, are known, data on NS5A are more limited. NS5A is a protein with 3 domains.