A novel synthetic bile acid derivative inhibits hepatitis B virus infection at entry step by interfering with the oligomerization of sodium taurocholate co-transporting polypeptide

Hepatitis B virus (HBV) infection is a major global health burden worldwide despite the availability of an effective vaccine and effective anti-HBV drugs. The currently approved anti-HBV drugs—i.e., nucleos(t)ide analogues and pegylated interferon α—can effectively suppress HBV replication, but rarely achieve a functional cure. Accordingly, new anti-HBV agents targeting different aspects of the HBV life cycle are needed. In this study, we screened for anti-HBV agents using the recombinant HBV expressing NanoLuc (NL) reporter gene (HBV/NL) and our original synthetic heterocyclic compound library. As a result, we identified a synthetic bile acid derivative, SO-145, as a potential novel anti-HBV agent, and investigated its effects in several cellular models of HBV. Treatment of HepG2-NTCP-C4 cells with SO-145 suppressed their NL activity following infection with HBV/NL. SO-145 suppressed HBV replication in PXB-cells infected with HBV genotype D, but did not show any inhibitory effect on HBV replication in Hep38.7-Tet cells. These results suggest that SO-145 specifically inhibits the early phase of the HBV life cycle. In other experiments, SO-145 was also shown to inhibit hepatitis D virus infection. Immunofluorescence analysis using fluorescent-labeled preS1 peptide revealed that SO-145 does not inhibit the preS1 attachment to the NTCP, but does markedly inhibit the HBV/preS1 internalization. Moreover, SO-145 does not inhibit the bile acid uptake facilitated by NTCP. Further mechanistic analysis suggested that SO-145 interferes with the NTCP oligomerization. Taken together, these results suggest that SO-145 inhibits HBV entry into hepatocytes by interfering with the NTCP oligomerization.