Wang Yang, Li Qiqi, Li Cheng, Wang Cong, Wang Shijie, Yuan Wenjie, Yu Demin, Zhang Ke, Shi Bisheng, Chen Xiaomei, Liu Tiantian, Yuan Zhenghong, Tong Shuping, Nassal Michael, Wen Yu-Mei, Wang Yong-Xiang
Key Laboratory of Medical Molecular Virology (MOE/NHC/CAMS), Shanghai Frontier Science Center of Pathogenic Microorganisms and Infection, School of Basic Medical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.
Shanghai Public Health Clinical Center, Shanghai Medical College, Fudan University, Shanghai, China.
Gut. 2024 Mar 7;73(4):668-681. doi: 10.1136/gutjnl-2023-330537.
Chronic hepatitis B (CHB) caused by HBV infection greatly increases the risk of liver cirrhosis and hepatocellular carcinoma. Hepatitis B surface antigen (HBsAg) plays critical roles in the pathogenesis of CHB. HBsAg loss is the key indicator for cure of CHB, but is rarely achieved by current approved anti-HBV drugs. Therefore, novel anti-HBV strategies are urgently needed to achieve sustained HBsAg loss.
We developed multiple chimeric antigen receptors (CARs) based on single-chain variable fragments (scFvs, namely MA18/7-scFv and G12-scFv), respectively, targeting HBV large and small envelope proteins. Their impacts on HBsAg secretion and HBV infection, and the underlying mechanisms, were extensively investigated using various cell culture models and HBV mouse models.
After secretory signal peptide mediated translocation into endoplasmic reticulum (ER) and secretory pathway, MA18/7-scFv and CARs blocked HBV infection and virion secretion. G12-scFv preferentially inhibited virion secretion, while both its CAR formats and crystallisable fragment (Fc)-attached versions blocked HBsAg secretion. G12-scFv and G12-CAR arrested HBV envelope proteins mainly in ER and potently inhibited HBV budding. Furthermore, G12-scFv-Fc and G12-CAR-Fc strongly suppressed serum HBsAg up to 130-fold in HBV mouse models. The inhibitory effect lasted for at least 8 weeks when delivered by an adeno-associated virus vector.
CARs possess direct antiviral activity, besides the well-known application in T-cell therapy. Fc attached G12-scFv and G12-CARs could provide a novel approach for reducing circulating HBsAg.
由乙肝病毒（HBV）感染引起的慢性乙型肝炎（CHB）极大地增加了肝硬化和肝细胞癌的风险。乙肝表面抗原（HBsAg）在CHB的发病机制中起关键作用。HBsAg消失是CHB治愈的关键指标，但目前获批的抗HBV药物很少能实现这一点。因此，迫切需要新的抗HBV策略来实现持续的HBsAg消失。
我们分别基于单链可变片段（scFv，即MA18/7-scFv和G12-scFv）开发了多种嵌合抗原受体（CAR），靶向HBV大、小包膜蛋白。使用各种细胞培养模型和HBV小鼠模型广泛研究了它们对HBsAg分泌和HBV感染的影响及其潜在机制。
在分泌信号肽介导转运至内质网（ER）和分泌途径后，MA18/7-scFv和CAR阻断了HBV感染和病毒粒子分泌。G12-scFv优先抑制病毒粒子分泌，而其两种CAR形式和连接可结晶片段（Fc）的版本均阻断HBsAg分泌。G12-scFv和G12-CAR主要将HBV包膜蛋白截留在ER中，并有效抑制HBV出芽。此外，G12-scFv-Fc和G12-CAR-Fc在HBV小鼠模型中使血清HBsAg强烈抑制达130倍。通过腺相关病毒载体递送时，抑制作用持续至少8周。
CAR除了在T细胞治疗中的众所周知的应用外，还具有直接抗病毒活性。连接Fc的G12-scFv和G12-CAR可为降低循环中的HBsAg提供一种新方法。
