Hepatitis C virus nonstructural protein 3–4A protease (HCV NS3-4A protease)

Hepatitis C virus nonstructural protein 3–4A protease (HCV NS3-4A protease) is a multifunctional, membrane-associated complex comprising the NS3 serine protease domain and the NS4A cofactor, essential for proteolytic cleavage of the HCV polyprotein at multiple sites required for viral replication[1][3][5][7]. The protease also disables host antiviral responses by cleaving immune adaptors such as MAVS (Cardif) and TRIF, allowing the virus to evade the innate immune system[1][3]. Extensive crystallographic and biochemical studies have revealed detailed mechanisms of substrate recognition and have guided the design of direct-acting antiviral (DAA) protease inhibitors, which form the backbone of curative combination therapies for chronic hepatitis C[2][6][8]. Drug resistance remains a therapeutic challenge due to rapid viral evolution, so next-generation inhibitors are designed to target conserved protease regions and minimize resistance[2][4]. The NS3-4A protease’s vital role in replication and immune evasion firmly establishes it as a central drug target in HCV infection.

Other names

HCV NS3/4A proteaseHepatitis C virus NS3-4A proteaseNS3 serine protease (with NS4A cofactor)NS3 protease-NS4A complexHCV nonstructural protein 3/4A protease

Direct inhibition of the NS3-4A serine protease active site, blocking cleavage of viral polyprotein, halting viral genome replication and maturation of viral proteins\nRestoration of host innate antiviral signaling by preventing cleavage of immune adaptor proteins like MAVS