Hepatitis C virus NS3 serine protease interacts with the serpin Cl inhibitor

Both NS3 protein (1007-1657) and its protease moiety (NS3p, 1027-1207) were able to interact in vitro with C1 Inhibitor (C1Inh) to give a 95-kDa M-r C1Inh cleavage product similar to that obtained upon protenlysis by complement protease Cls, High-M-r, reaction products were also detected after incubation of C1Inh with NS3 bat not with NS3p; they correspond to ester-bonded complexes from their hydroxylamine lability, Similar reactivity of NS3 was observed upon incubation with alpha 2-antiplasmin. Serpin cleavage was prevented by treatment of NS3 with synthetic serine protease inhibitors. This interaction between viral NS3 and host serpins suggests that NS3 is likely to be controlled by infected cell protease inhibitors, (C) 1999 Federation of European Biochemical Societies.