HCV NS2-3 cDNA that encodes the Zn 2+ -dependent metalloprotease was amplified by RT-PCR from serum of a Chinese patient infected with HCV. By using a baculovirus expression system, the cloned NS2-3 cDNA was expressed in Sf9 insect cells. SDS-PAGE and Western blot analyses showed the NS2-3 protein product as well as the product corresponding to HCV protein cleaved from NS2-3 precursor. The results indicated that the expressed NS2-3 protein is likely of protease activity and carries out autocleavage at the NS2-NS3 junction. The expression of NS2-3 protease in Sf9 insect cells allows the study on the biological function of NS2-3 protease and constitutes the basis for testing influencing agents on NS2-3 protease activity.
