(A) Structures of boceprevir and telaprevir. (B) Three-dimensional structure of NS3 protease-inhibitor complex. The structures of boceprevir (purple, right panel) and telaprevir (gold, left panel) are presented as stick models. Side chains of the active site Ser (Ser139) and two mutation sites (V158 and V163) are depicted on the Connolly surface of the NS3 protease.