Sphondin efficiently blocks HBsAg production and cccDNA transcription through promoting HBx degradation

作者：Fang Ren, Junchi Hu, Yongjun Dang, Haijun Deng, Ji‐Hua Ren, Sheng‐Tao Cheng, Ming Tan, Hui Zhang, Xin He, Haibo Yu, Juan Zhang, Zhenzhen Zhang, Weixian Chen, Jieli Hu, Xue-Fei Cai, Yuan Hu, Ailong Huang, Juan Chen · 发表于：Journal of Medical Virology · 年份：2023 · DOI：10.1002/jmv.28578 · 被引用次数：16 · 研究领域：Hepatitis B Virus Studies、Hepatitis C virus research、Viral gastroenteritis research and epidemiology

Hepatitis B surface antigen (HBsAg) loss and seroconversion, which is considered as functional cure of chronic Hepatitis B virus (HBV) infection, is rarely achieved even after long-term antiviral treatments. Therefore, new antiviral strategies interfering with other HBV replication steps are required, especially those that could efficiently inhibit HBsAg production. Here, we identified novel anti-HBV compounds that could potently block HBsAg expression from cccDNA by screening a natural compound library derived from Chinese traditional medical plants by a novel screening strategy. The combination of ELISA assay detecting the HBsAg and real-time PCR detecting HBV RNAs as indicator for cccDNA transcriptional activity were used. The antiviral activity of a candidate compound and underlying mechanism were evaluated in HBV-infected cells and a humanized liver mouse model. Herein, we selected a highly effective low-cytotoxic compound sphondin, which could effectively inhibit both intracellular HBsAg production and HBV RNAs levels. Moreover, we found that sphondin markedly inhibited cccDNA transcriptional activity without affecting cccDNA level. Mechanistic study found sphondin preferentially bound to HBx protein by residue Arg72, which led to increased 26S proteasome-mediated degradation of HBx. Sphondin treatment significantly reduced the recruitment of HBx to cccDNA, which subsequently led to inhibition of cccDNA transcription and HBsAg expression. The absence of HBx or R72A muta...