ns2-3 protease is the enzyme responsible for proteolytic cleavage between the non-structural proteins ns2 and ns3. ns3 protease, on the other hand, is responsible for the cleavage of non-structural proteins downstream. both of these proteases are directly involved in hcv genome replication. ns2-3 protease mechanism is essential for viral production, as shown by in-vitro chimpanzee studies where chimps which were inoculated with hcv with fully mutated ns2-3 protease activity didn’t develop hcv infection.