Worldwide nearly 200 million people are estimated to be chronically infected with the hepatitis C virus (HCV) and are at risk of developing severe liver disease. Current standard therapy consists of a combination of pegylated interferon (PEG-IFN) with ribavirin (RBV) and a protease inhibitor (PI).

Our collaborators of the University of Zaragoza, Spain, have recently identified several molecules that inhibit the viral protease NS3 in a different way than the currently described PIs. These molecules act as allosteric inhibitors because they stabilize the partially folded Zn2+-free inactive conformation of the viral protease. The identified ligands that bind the Zn2+-free NS3 trap the inactive protease thereby blocking the viral life cycle. The efficacy of these compounds has been confirmed in replicon cell assays. Importantly, direct calorimetric assays revealed a low impact of known resistance-associated mutations, and enzymatic assays provided direct evidence of their inhibitory activity. These molecules have several advantages over the current PI: 1) they have a different mode-of-action, simultaneously blocking the interaction between the protease and its substrate and NS4A cofactor in a non-competitive fashion; 2) there is only a low impact of known PI resistance-associated mutations; 3) they constitute new low molecular-weight scaffolds that can be further optimized; and 4) they may be used in combination with other PI, polymerase inhibitors and other direct antiviral in general. The aim of this project is to confirm the antiviral activity of these new PI in a humanized mouse model. This pre-clinical efficacy studies are essential to valorize this invention.