FIG 4.

Levels of resistance of HCV genotype 2 to 6 recombinants with engineered NS3P substitutions to telaprevir (TVR), boceprevir (BOC), vaniprevir (VAN), grazoprevir (GRA), simeprevir (SMV), and paritaprevir (PTV). The level of resistance is expressed as the fold change in the EC₅₀, which was calculated by comparing the EC₅₀ of a variant to the EC₅₀ of the original virus of the same genotype and isolate, as described in Materials and Methods. Fold resistance values are color-coded. The substitutions tested were selected under treatment with TVR and/or BOC; a boxed value indicates under which of these two PIs a particular amino acid substitution was selected. ^a, the indicated mean EC₅₀ values (expressed as nanomolar concentrations) were determined previously for each original recombinant (28), and similar EC₅₀ values were obtained for the original viruses in the current study. ^b, the numbering for engineered amino acid substitutions is relative to that for the reference strain H77 (GenBank accession no. AF009606). ^c, except for genotype 3a (isolate 452) R155K, the fold resistance of R155K and A156S variants has been determined previously (28) and is in agreement with the values obtained in the current study. ^d, the fold resistance was obtained from reference 28. ^e, ND, not determined. Resistance to simeprevir and paritaprevir was determined only for substitutions that either (i) conferred ≥2-fold resistance to vaniprevir and/or grazoprevir as single substitutions, (ii) conferred ≥2-fold resistance to vaniprevir and/or grazoprevir in combination with other NS3P substitutions, or (iii) were identified at position 54, 155, or 156. ^f, the indicated variant was <50% inhibited by the highest concentration of vaniprevir applied (15,000 nM). Asterisks indicate the following additional substitutions in NS3P acquired by the indicated first-passage stocks: I177V in genotype 2a (isolate J6) T72M, P86L in genotype 2a (isolate J6) A156S, Q168K in genotype 3a (isolate 452) R155K, N29K and L127M in genotype 4a (isolate ED43) N77S, I17M in genotype 5a (isolate SA13) E30V and in genotype 5a (isolate SA13) E30V plus A156S, and A116P in genotype 6a (isolate HK6a) T54A plus A156S. Similarly, the genotype 4a (isolate ED43) F14C second-passage stock acquired G90A.