Betulonic Acid Inhibits HBV Replication via Modulating ERK1/2-HNF4α Axis

Background: Chronic hepatitis B virus (HBV) infection continues to pose a significant global public health burden. Existing therapies achieve functional cures at limited rates and are complicated by problems including drug resistance and cumulative toxicity. Betulonic acid (Bet) is known for its anti-inflammatory, antibacterial, and antitumor activities. However, whether its antimicrobial effects extend to HBV infection remains unclear. Consequently, this study investigates the antiviral effects of Bet both in vitro and in vivo. Methods: Bet effect on HBV replication and transcription was first investigated using Enzyme-Linked Immunosorbent Assay (ELISA) and real-time quantitative reverse transcription (RT-qPCR). Western blot and RNA-seq analyses were performed to elucidate the antiviral mechanism. Finally, animal experiments were conducted to assess the in vivo anti-HBV effect of Bet. Results: In vitro experiments demonstrated that Bet significantly inhibited secretion of HBsAg and HBeAg, reduced HBV total RNA and pregenomic RNA levels, and exerted antiviral effects by modulating the extracellular signal-regulated MAP kinases (ERK1/2)-hepatocyte nuclear factor 4 alpha (HNF4α) axis. Concurrently, the reduction in serum HBV DNA copy number in infected mice confirmed the therapeutic efficacy of Bet against HBV infection in vivo. Conclusion: These results demonstrate that Bet exhibits anti-HBV activity, which could inform new drug development strategies for HBV.