A novel in vitro system for simultaneous infections with hepatitis B, C, D and E viruses

Background & Aims The liver, and more precisely hepatocytes, can be infected by several hepatotropic viruses, including HBV, HDV, HCV and HEV, with chronic infection leading to end-stage liver diseases. Since no in vitro model allowing multi-infections with the four viruses is reported, limited data are available on their interplay as well as on the potential cross-reactivity of antivirals in multi-infection cases. The aim of our study was to set up such a model. Methods HuH7.5-NTCP cells were cultured with 2% DMSO (dimethyl sulfoxide) for 1 week to allow partial differentiation into hepatocytes (dHuH7.5-NTCP) before infection with the different viruses and treatment with known antiviral molecules. Results We observed increased expression of liver specific transcripts and production of ApoB containing VLDL in dHuH7.5-NTCP cells and replication of HBV, HDV, HCV and HEV for at least 4 weeks after mono or multiple infections. We recapitulated the known antiviral effect of sofosbuvir on HCV and HEV (>90% reduction in the levels of intracellular viral RNAs, p <0.0005) and of IFN-α on HCV, HEV and HDV (80% reduction in the levels of intracellular viral RNAs, p <0.0005). Besides its already described antiviral effect on HBV and HDV, we observed that GW4064, a farnesoid X receptor (FXR) agonist, also strongly inhibited HEV replication (85 to 95% reduction in the levels of intracellular HEV RNAs, p <0.0005). Using HEV-infected HuHep mice, we confirmed the antiviral effect of vonafexor, an FXR agonist, that is currently being tested clinically against HBV/HDV. Conclusions We set-up the first in vitro model allowing multi-infections with hepatitis viruses that can be used for broad drug screening and highlighted FXR ligands as potential broad-acting antivirals. Impact and implications Hepatitis virus infections caused by HBV, HCV, HDV, and HEV represent a global health threat. Treatment options remain limited, notably due to the lack of knowledge about molecular virus-host interactions. Moreover, the interplay between these four viruses in the context of co-infections remains unknown. In this study, we report the first in vitro system that allows for mono and multi-infections with these four viruses and characterize the broad antiviral activity of farnesoid X receptor agonists, paving the way for the development of new strategies for viral cure.