Nonstructural protein 3 (NS3) (NS3)

Nonstructural protein 3 (NS3) is a multifunctional viral protein essential for the replication and pathogenesis of the Hepatitis C virus (HCV) (UniProt). It consists of an N-terminal serine protease domain and a C-terminal RNA helicase/NTPase domain (Wikipedia). The protease domain, in complex with its cofactor NS4A, is responsible for the proteolytic processing of the viral polyprotein into functional nonstructural proteins (NIH). Additionally, NS3/4A cleaves host cell signaling proteins such as MAVS and TRIF to subvert the innate immune response, facilitating chronic infection (PubMed). The helicase domain is involved in unwinding double-stranded RNA intermediates during viral genome replication and may play a role in virus assembly (RCSB PDB). Due to its critical roles, NS3 is a primary target for direct-acting antiviral (DAA) drugs, specifically NS3/4A protease inhibitors (StatPearls). Drugs such as glecaprevir and grazoprevir have revolutionized HCV treatment by providing high cure rates and improved safety profiles compared to earlier generations (Frontiers in Pharmacology). However, the emergence of resistance-associated substitutions (RASs) remains a challenge for long-term efficacy (NIH).

Other names

NS3 proteaseNS3 helicaseNS3-4A complexp-70HCV NS3

NS3/4A protease inhibition