Hepatitis C virus (HCV) genotype 2a, also known as HCV2a, is a fusion protein of a.a. 21-32 of NS4A, linker (4 a.a.) and a.a. 3-181 of NS3 (GenBank Accession No. FJ393024) with N-terminal FLAG-His-tag, MW = 22.3 kDa, expressed in an E. coli expression system.