1. Academic Validation
  2. Identification and characterization of a novel hepatitis B virus pregenomic RNA encapsidation inhibitor

Identification and characterization of a novel hepatitis B virus pregenomic RNA encapsidation inhibitor

  • Antiviral Res. 2020 Mar;175:104709. doi: 10.1016/j.antiviral.2020.104709.
Eunji Jo 1 Dong-Kyun Ryu 1 Alexander König 1 Soonju Park 2 Yoojin Cho 1 Sang-Hyun Park 1 Tae-Hee Kim 2 Seung Kew Yoon 3 Wang-Shick Ryu 4 Jonathan Cechetto 2 Marc P Windisch 5
Affiliations

Affiliations

  • 1 Applied Molecular Virology Laboratory, Institut Pasteur Korea, 696 Sampyung-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea.
  • 2 Screening Discovery Platform, Institut Pasteur Korea, 696 Sampyung-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea.
  • 3 Catholic University Liver Research Center, The Catholic University of Korea, Seoul, South Korea.
  • 4 Department of Biochemistry, Yonsei University, Seoul, South Korea.
  • 5 Applied Molecular Virology Laboratory, Institut Pasteur Korea, 696 Sampyung-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, South Korea; Division of Bio-Medical Science and Technology, University of Science and Technology, 217, Gajeong-ro, Yuseong-gu, Daejeon, South Korea. Electronic address: marc.windisch@ip-korea.org.
Abstract

Currently, therapies to treat chronic hepatitis B (CHB) Infection are based on the use of interferon-α or nucleos(t)ide analogs (NAs) to prevent viral DNA synthesis by inhibiting the Reverse Transcriptase activity of the hepatitis B virus (HBV) polymerase (Pol). However, these therapies are not curative; thus, the development of novel anti-HBV agents is needed. In accordance with this unmet medical need, we devised a new target- and cell-based, high-throughput screening assay to identify novel small molecules that block the initial interaction of the HBV Pol with its replication template the viral pregenomic RNA (pgRNA). We screened approximately 110,000 small molecules for the ability to prevent HBV Pol recognition of the pgRNA 5' epsilon (ε) stem-loop structure, identifying (Z)-2-(allylamino)-4-amino-N'-cyanothiazole-5-carboximidamide (AACC). Viral nucleocapsid-captured quantitative RT-PCR and Western blot results revealed that AACC significantly decreased encapsidated pgRNA levels and blocked capsid assembly without affecting core protein expression in stable HBV-replicating cells. As a result, both intra- and extracellular accumulation of viral DNA was strongly reduced. AACC treatment of HepG2-sodium taurocholate transporting polypeptide (NTCP) cells and primary human hepatocytes infected with cell culture- or patient-derived HBV isolates showed both time- and dose-dependent inhibition of infectious viral progeny and rcDNA production. Furthermore, AACC showed cross-genotypic activity against genotypes B, C, and D. Of note, AACC inhibited the viral replication of lamivudine and a capsid inhibitor-resistant HBV, and showed synergistic effects with NAs and a capsid inhibitor. In conclusion, we identified a novel class of compounds specifically targeting the ε-Pol interaction and thereby preventing the encapsidation of pgRNAs into viral capsids. This promising new HBV inhibitor class potently inhibits HBV amplification with distinct characteristics from existing NAs and other drugs currently under development, promising to add value to existing therapies for CHB.

Keywords

Encapsidation; Epsilon signal; Hepatitis B virus; High-throughput drug screening; Polymerase; Pregenomic RNA.

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