Identification of low-molecular compounds that inhibit envelope formation of hepatitis B virus.

Agents with novel mechanisms are clinically needed for the functional cure of chronic hepatitis B virus (HBV) infection. This study aimed to identify compounds that inhibit an interaction between large hepatitis B surface (LHBs) and hepatitis B core (HBc) proteins, which are considered to be important for HBV envelope formation. Using a high-throughput screening method to evaluate the protein-protein interaction in HepG2 cells by the NanoBRET system, 3,200 compounds from our library were tested. Then, the inhibitory effects of the hit compounds on HBV particles with the envelope were evaluated in HBV-expressing HepG2.2.15.7 cells. 40 hit compounds were found to inhibit the interaction between LHBs and HBc, of which 10 compounds inhibited HBV particles. The top 5 compounds with the least variation were considered as candidates. These compounds showed little effects on HBV proteins and RNAs, whereas a hit compound 16, which showed the lowest IC50 (0.9 µM), decreased precore mRNA significantly. When the culture supernatant from cells with hit compound 16 was subjected to sucrose density gradient centrifugation, HBV particles with the envelope were found to be reduced. In conclusion, we identified compounds that might inhibit the envelope formation of HBV through disturbing the interaction between LHBs and HBc.