Negative Regulation of Mitochondrial Antiviral Signaling Protein-Mediated Antiviral Signaling by the Mitochondrial Protein LRPPRC During Hepatitis C Virus Infection.

Abstract

Hepatitis C virus (HCV) is highly efficient in establishing a chronic infection, having evolved multiple strategies to suppress the host antiviral responses. The HCV nonstructural 5A (NS5A) protein, in addition to its role in viral replication and assembly, has long been known to hamper the interferon (IFN) response. However, the mechanism of this inhibitory activity of NS5A remains partly characterized. In a functional proteomic screening carried out in HCV replicon cells, we identified the mitochondrial protein LRPPRC as an NS5A binding factor. Notably, we found that downregulation of LRPPRC expression results in a significant inhibition of HCV infection, which is associated with an increased activation of the IFN response. Moreover, we showed that LRPPRC acts as a negative regulator of the mitochondrial-mediated antiviral immunity, by interacting with mitochondrial antiviral signaling protein (MAVS) and inhibiting its association with TRAF3 and TRAF6. Finally, we demonstrated that NS5A is able to interfere with MAVS activity in a LRPPRC-dependent manner. Conclusion: Overall, our results indicate that NS5A contributes to the inhibition of innate immune pathways during HCV infection by exploiting the ability of LRPPRC to inhibit MAVS-regulated antiviral signaling.