Étude de la duplication du domaine V3 de la région NS5A du virus de l’hépatite C de génotype 1b : épidémiologie clinique et moléculaire et aspects fonctionnels.

The hepatitis C virus (HCV) infection leads to chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC). The HCV NS5A protein has been shown to be involved in viral replication and assembly and in the liver carcinogenesis. We investigated a V3-NS5A polymorphism in HCV 1b identified in our laboratory. We found two V3 domains tandemly duplicated without ORF disruption in 3.05% of the HCV sequences. The prevalence of this duplication increased with liver disease severity (from 3.0% in patients without cirrhosis to 9.4% in patients with both cirrhosis and HCC, p for trend=0.045). Direct sequencing and clonal analyzes showed that quasispecies were entirely composed by mutants strains that persisted at least for 10 years. These V3 duplications were likely resulting from a non-homologous recombination that occurred between two wild-type strains. Our preliminary functional results identified potential specific interactions between host-cell proteins and the V3-NS5A duplicated proteins using a yeast two-hybrid system. We expressed recombinant duplicated NS5A proteins in cell and bacterial cultures and developed an optimized protocol for bacterial cultures. A validation of the interactions has not been reached with the first pull-down assays. We identified a V3-NS5A duplication in HCV 1b for the first time (i) associated with unfavorable evolution of liver disease including a possible involvement in liver carcinogenesis (ii) always present during the HCV infection (iii) resulting from a non-homologous recombination, mechanism that has never been described in vivo in HCV. We also suggested potential specific protein-protein interactions and performed recombinant NS5A protein production.