Hepatitis D virus infection of stem cell-derived hepatocytes triggers an IFN- and NFkB-based innate immune response unable to clear infection.

Abstract

Human pluripotent stem cell-derived hepatocyte-like cells (HLCs) are a valuable model to investigate host-pathogen interactions of hepatitis viruses in a mature and authentic environment. Here, we investigated the susceptibility of HLCs to the Hepatitis D Virus (HDV), a virus that in co-infection with HBV is responsible for the most severe form of viral hepatitis. Cells undergoing hepatic differentiation became susceptible to HDV infection after acquiring expression of the Na+-taurocholate cotransporting polypeptide (NTCP), the receptor mediating HBV and HDV entry. Inoculation of mature HLCs with HDV lead to increasing amounts of intracellular HDV RNA and accumulation of the HDV antigen in the cells. The infection was abrogated when using known entry inhibitors targeting NTCP or by disrupting genome replication using the nucleoside analogue Ribavirin. Upon infection, the HLCs mounted an innate immune response based on induction of the interferons IFNB and L, but not IFNA, and were associated with an upregulation of interferon-stimulated genes. The intensity of this immune response positively correlated with the level of viral replication and was dependant on both the JAK/STAT and NF{kappa}B pathway activation. Importantly, neither this innate immune response nor an exogenous treatment of IFN2b inhibited HDV replication. However, pre-treatment of the HLCs with IFN2b reduced viral infection, suggesting that ISGs may limit early stages of infection. This novel HDV in vitro infection model represents a valuable tool for studying HDV replication and investigating candidate antiviral drugs in cells displaying mature hepatic functions. Lay summaryHDV can infect stem cell-derived hepatocytes through an NTCP-mediated entry process. Infection triggers an IFN and NF{kappa}B dependent innate immune response. However, viral replication seems unaffected by this innate response or by exogenous IFN treatment. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=140 SRC="FIGDIR/small/502443v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@44ca7forg.highwire.dtl.DTLVardef@4a7be3org.highwire.dtl.DTLVardef@b9c3corg.highwire.dtl.DTLVardef@3e66c3_HPS_FORMAT_FIGEXP M_FIG C_FIG