Recombinant virus HCV1b (Hepatitis C Virus, genotype 1b), encompassing amino acids 3-181 and cofactor NS4A encompassing amino acids 21-32. This construct is a fusion protein corresponding to the serine protease NS3. The protein contains the mutation of interest (R155K). The construct contains an N-terminal Flag-tag followed by a His-tag (6xHis). The recombinant protein was affinity purified.