Due to the limitations of current anti-HBV therapies, the HBV core (HBc or HBcAg) protein assembly modulators (CpAMs) are believed to be potential anti-HBV agents. Therefore, discovering safe and efficient CpAMs is of great value. In this study, we established a HiBiT-based high-throughput screening system targeting HBc and screened novel CpAMs from an in-house marine chemicals library. A novel lead compound 8a, a derivative of the marine natural product naamidine J, has been successfully screened for potential anti-HBV activity. Bioactivity-driven synthesis was then conducted, and the structure‒activity relationship was analyzed, resulting in the discovery of the most effective compound 11a (IC₅₀ = 0.24 μmol/L). Furthermore, 11a was found to significantly inhibit HBV replication in multiple cell models and exhibit a synergistic effect with tenofovir disoproxil fumarate (TDF) and IFNa2 in vitro for anti-HBV activity. Treatment with 11a in a hydrodynamic-injection mouse model demonstrated significant anti-HBV activity without apparent hepatotoxicity. These findings suggest that the naamidine J derivative 11a could be used as the HBV core protein assembly modulator to develop safe and effective anti-HBV therapies.

It is known that hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) persists in the nucleus of infected hepatocytes in the form of minichromosome and is difficult to target and eliminate. Studies on the mechanisms and strategies for persistent silencing or elimination of HBV cccDNA are the focus achieving for “functional cure” of chronic hepatitis B. This article introduces the current knowledge on the basic biological features of cccDNA, regulatory mechanisms of transcription and metabolism, and related host factors, with a focus on the potential pathways and strategies for cccDNA silencing or elimination.