Hepatitis C virus non-structural protein NS5A (NS5A) (NS5A)

Hepatitis C virus non-structural protein NS5A is a multifunctional phosphoprotein that is essential for the replication and assembly of the Hepatitis C virus (HCV) (PMID: 26838668). Although it lacks intrinsic enzymatic activity, NS5A acts as a critical scaffold, interacting with other viral proteins like NS5B and host cell factors such as PI4KIIIα to form the viral replication complex on the endoplasmic reticulum membrane (PMID: 23824382). The protein is organized into three domains: Domain I is a structured zinc-binding domain involved in RNA binding and membrane association, while Domains II and III are intrinsically disordered and play roles in RNA replication and viral particle assembly, respectively (UniProt P26664). NS5A also modulates host immune responses, particularly by antagonizing the interferon-alpha response, which contributes to viral persistence and disease progression to cirrhosis and hepatocellular carcinoma (PMID: 10482586). As a therapeutic target, NS5A is inhibited by a class of direct-acting antivirals (DAAs) known as NS5A inhibitors, which bind to Domain I and disrupt both the replication and assembly stages of the viral life cycle (PMID: 20445623). These inhibitors are highly potent and are standard components of modern, interferon-free combination therapies for chronic hepatitis C.

Other names

Non-structural protein 5AHCV NS5Ap56p58NS-5 protein

NS5A inhibitors bind to the N-terminal Domain I of the NS5A protein, likely inducing a conformational change that disrupts the assembly of the viral replication complex and prevents the formation of new viral particles (PMID: 20445623, 23824382).