NS3

The nonstructural 3 (NS3) protein is a bifunctional enzyme that has serine protease and helicase activity. The serine-type protease region of NS3 is responsible for most of the cleavages of the viral polyprotein that free nonstructural proteins. In addition, NS3 plays a role in subverting the innate host immune response by proteolytically inactivating various host cell factors that can block viral replication. The helicase region of N3 likely plays a role unwinding the viral RNA and supporting viral replication. One of the first advances in the development of direct-acting antiviral therapy was solving the crystal structure of the NS3 protease which allowed the design of specific NS3/4A protease inhibitors.