Characterization of NS3 protease from an Egyptian HCV genotype 4a isolate.

The role of the NS3 protease in HCV replication was demonstrated by the ability of a protease inhibitor cocktail (10 microg/ml) to abolish the induced cytopathic effect in RAW macrophages upon infection with Egyptian sera. The HCV protease gene was amplified from Egyptian sera by nested PCR and cloned downstream of the CMV promotor in a mammalian expression plasmid, which was then used to transform bacteria. Colonies carrying the gene in the correct orientation were subjected to large-scale plasmid purification followed by sequencing.