Hepatitis C virus non-structural protein 5A (NS5A) (NS5A)

Hepatitis C virus non-structural protein 5A (NS5A) is a multifunctional zinc-binding phosphoprotein that is essential for the HCV life cycle (UniProt: P26664). While it possesses no known enzymatic activity, it serves as a critical scaffold for the viral replication complex, interacting with the NS5B polymerase and host factors to facilitate RNA replication (PubMed: 26129818). NS5A also plays a pivotal role in the assembly of new virions and the modulation of host cell signaling pathways, including the inhibition of the interferon-induced antiviral response. Chronic infection driven by NS5A-mediated replication can lead to severe liver pathologies such as cirrhosis and hepatocellular carcinoma (StatPearls: Hepatitis C). As a therapeutic target, NS5A is highly sensitive to direct-acting antivirals (DAAs) like daclatasvir and ledipasvir. These drugs bind to the protein's N-terminal domain, causing a rapid redistribution of the protein and disrupting both the replication and assembly stages of the viral life cycle (PubMed: 25514353).

Other names

Non-structural protein 5AHCV NS5Ap56p58NS5A replication complex protein

NS5A inhibitors bind to the N-terminal Domain I of the NS5A protein, which is thought to interfere with its dimerization and its interaction with other components of the replication complex, effectively halting viral RNA synthesis and virion assembly (PubMed: 25514353).