Related Experiment Video
Updated: Jul 12, 2025
Development of a Hepatitis B Virus Reporter System to Monitor the Early Stages of the Replication Cycle
Published on: February 1, 2017
Development of anti-HBV agents targeting HBV capsid proteins
Takuya Kobayakawa1, Masayuki Amano2,3, Miyuki Nakayama1
1Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University (TMDU) 2-3-10 Kandasurugadai, Chiyoda-ku Tokyo 101-0062 Japan tamamura.mr@tmd.ac.jp.
Insights
Researchers identified a novel compound, Cpd4, that targets the hepatitis B virus (HBV) capsid protein. This compound and its derivatives show potential for a complete cure by reducing viral markers like HBcrAg and HBsAg.
Area of Science:
- Hepatology
- Virology
- Medicinal Chemistry
Background:
- Hepatitis B virus (HBV) infection can lead to chronic hepatitis, cirrhosis, and liver cancer.
- A complete cure for HBV requires eliminating the virus and covalently closed circular DNA (cccDNA).
- The hepatitis B capsid protein (HBc) is crucial for viral DNA encapsulation and regulates cccDNA transcription, making it a potential therapeutic target.
Purpose of the Study:
- To identify small molecules targeting the HBc protein for a potential cure of hepatitis B.
- To design and synthesize novel HBc inhibitors based on an initial lead compound.
- To investigate the structure-activity relationships of these inhibitors to optimize anti-HBV activity.
Main Methods:
- *In silico* screening of a compound library to identify HBc binders.
- Synthesis of Cpd4 and its derivatives.
- Anti-HBV assays to measure reductions in HBV core related antigen (HBcrAg) and HBV surface antigen (HBsAg).
- Structure-activity relationship analysis of synthesized compounds.
Main Results:
- A small compound, Cpd4 (1), was identified that binds to a hydrophobic cavity in the HBc protein.
- Cpd4 reduced levels of HBcrAg and HBsAg, indicating anti-HBV activity.
- Twenty derivatives of Cpd4 were synthesized, leading to the discovery of a more potent compound, TKB-HBV-CA-001 (3b).
- Compound efficacy appears related to the shape and size fitting the hydrophobic cavity, rather than specific amino acid interactions.
Conclusions:
- The identified compounds, particularly TKB-HBV-CA-001, show promise as novel therapeutic agents against HBV.
- Targeting the HBc protein's hydrophobic cavity offers a viable strategy for developing a complete cure for hepatitis B.
- Further development of these HBc inhibitors could lead to new treatments for chronic HBV infection.
Abstract:
Hepatitis B is a viral hepatitis, which is caused by infection of hepatitis B virus (HBV). This disease progresses to chronic hepatitis, cirrhosis and liver cancer. To treat hepatitis B, exclusion of virus and covalently closed circular DNA (cccDNA) that is formed in hepatocyte nucleus is necessary. A hepatitis B capsid protein (HBc) is an indispensable protein, which forms the capsid that encapsulates viral DNA. Since HBc is correlated to the transcriptional regulation of cccDNA, this protein would be an attractive target for complete cure of hepatitis B. By in silico screening of a library of compounds, a small compound, Cpd4 (1), which binds to a hydrophobic cavity located in the inner pocket on the tetramer interface of HBc proteins, was identified. In anti-HBV assays, this synthetic compound, Cpd4 (1) decreased the amount of HBV core related antigen (HBcrAg), which has been correlated with the proliferation of HBV, and decreased the amount of HBV surface antigen (HBsAg), which is correlated with the amount of cccDNA. Based on Cpd4 (1) as a lead compound, 20 derivatives of 1 were designed and synthesized and their structure-activity relationships were examined. As a result, specific interactions between each compound and amino acid residues of the target protein appeared to be unimportant but the shape/size of compounds which can bind to the hydrophobic cavity might be important in the expression of high anti-HBV activity, and a more potent derivative, TKB-HBV-CA-001 (3b), was discovered. These results will be useful in the development of novel anti-HBV agents for a complete cure of hepatitis B.
