The recombinant HCV NS3/4A protease mutant T54A is derived from its wild type (NCBI Accession: CAB46913) with a substitution of Thr 54 with Ala. This single mutation is reported to confer low to moderate levels of reistance (<20-fold) to the protease inhibitor SCH 503034. This mutated form is important to be tested when screening for new HCV NS3/4A protease inhibitors.