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Efficient Inhibition of Hepatitis B Virus (HBV) Replication and cccDNA Formation by HBV Ribonuclease H Inhibitors
Ranjit Chauhan1, Qilan Li1,2, Molly E Woodson1,2
1Department of Molecular Microbiology and Immunology, School of Medicine, Saint Louis Universitygrid.262962.b, Saint Louis, Missouri, USA.
Antimicrobial Agents and Chemotherapy
|September 13, 2021
Summary
Hepatitis B virus (HBV) ribonuclease H (RNase H) inhibitors show high efficacy in infected cells, suppressing viral DNA and antigen production. These compounds are safe in primary human cells and effective against drug-resistant HBV strains, supporting their use in combination therapies.
Area of Science:
- Hepatology and Virology
- Antiviral Drug Development
Background:
- The hepatitis B virus (HBV) ribonuclease H (RNase H) is a promising drug target, but its inhibition has faced limitations in efficacy assessment, cytotoxicity evaluation, and activity against resistant strains.
- Current RNase H inhibitor development has primarily used transfected cell lines for efficacy and transformed cell lines for cytotoxicity, with limited data on resistant HBV strains.
Purpose of the Study:
- To evaluate the efficacy of three RNase H inhibitors (110, 1133, and 1073) in HBV-infected cells, addressing limitations in previous studies.
- To assess the cytotoxicity of these inhibitors in primary human hepatocytes and their effectiveness against nucleos(t)ide analog-resistant HBV strains.
Main Methods:
- Three RNase H inhibitors (α-hydroxytropolone, N-hydroxypyridinedione, and N-hydroxynapthyridinone) were tested in HBV-infected HepG2-NTCP cells.
- Inhibition of covalently closed circular DNA (cccDNA) accumulation and HBV product formation was measured.
- Cytotoxicity was assessed in HepG2-derived cell lines and primary human hepatocytes; efficacy against wild-type and resistant HBV strains was determined.
Main Results:
- RNase H inhibitors demonstrated significantly higher efficacy (EC50s of 0.049-0.078 μM) in infected cells compared to transfected cells (0.29-1.6 μM).
- Compounds suppressed cccDNA formation by >98% and robustly inhibited HBV RNA, DNA, and HBsAg secretion, particularly when added early post-infection.
- Inhibitors showed no toxicity in primary human hepatocytes and maintained similar efficacy against wild-type and resistant HBV strains.
Conclusions:
- Inhibiting HBV RNase H is a validated drug strategy, with compounds showing enhanced efficacy in infected cells and favorable safety profiles.
- RNase H inhibitors are effective against drug-resistant HBV and warrant inclusion in novel curative combination therapies for hepatitis B.
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