Hepatitis C virus (HCV) helicase (non-structural protein 3, NS3) is involved in HCV genome replication and is considered a target for inhibition of HCV. Protease NS2-3 is a cysteine protease responsible for the autocatalytic cleavage of NS2-NS3. The protease is self-inactivated following maturation. NS3 has three enzymatic activities: serine protease, NTPase and RNA helicase. NS3 serine protease in association with NS4A is responsible for the cleavages of NS3-NS4A, NS4A-NS4Bovine, NS4B-NS5A and NS5A-NS5B. NS3/NS4A comple, Xenopus/Amphibian, also prevents phosphorylation of human IRF3, thus preventing the establishment of dsRNA induced antiviral state. NS3 RNA helicase binds to RNA and unwinds dsRNA in the 3' to 5' direction, and likely RNA stable secondary structure in the template strand. NS3 cleaves and inhibits the host antiviral protein MAVS.