About 170 million people worldwide are infected with hepatitis C virus (HCV). The virus uses a series of entry factors expressed at the cell surface to enter into hepatocytes. Among these factors, CLDN-1 and CD81 form a complex that is essential for HCV entry. Indeed, silencing expression of one partner or point mutations preventing the complex formation both inhibits viral entry. CD81/CLDN-1 complex then represents a new interesting therapeutic target in the fight against hepatitis C.

The project aims to optimize new series of compounds active against HCV infection by targeting the protein complex CD81/CLDN1, in order to understand molecular mechanisms involved in this interaction during virus entry, and to validate this complex as a new target to prevent HCV entry.

To find molecules able to promote changes in the conformation of the complex CD81/CLDN-1, we developed a high throughput screening assay based on the BRET (Bioluminescence Resonance Energy Transfer) technology. A primary screening of 15,600 compounds from our chemical library was carried out and led to the identification of 380 molecules modulating the conformation of this complex. These molecules were selected for dose response experiments and 152 were identified as positive. These compounds were then validated as inhibitors of viral infection using a secondary assay. Two families of compounds have shown very promising inhibitory activities and analogues are currently synthesizing to increase the activity and establish structure-activity relationships.