X蛋白（HBx）在乙肝病毒（HBV）感染和复制中起关键作用。目前还没有干预HBx功能的有效手段，HBx与互作蛋白的作用机制也待深入研究。课题组前期获得了HBx的单抗2A7和2A2。2A7的表位位于HBx与DDB1的结合区。HBx可通过结合DDB1促使胞内抗病毒蛋白的降解。2A7能阻断HBx与DDB1的互作。2A2的表位位于HBx的负性调节区，该区域在HBV感染和复制中的作用尚不清楚。我们获得了2A7和2A2的重链和轻链可变区的核酸编码序列，构建了单链抗体。本课题将对2A7和2A2单链抗体进行改造优化，使之适于以胞内抗体的形式在细胞内表达；并探索通过穿膜肽介导的方式将2A7和2A2单抗导入细胞。研究利用HBx胞内抗体抑制HBV感染和复制的可能性及分子机制，发现新的HBx互作蛋白，进一步阐明HBx在HBV感染和复制中的功能，为研发以HBx为靶标的新型抗HBV药物提供理论依据和技术方法。

X protein (HBx) plays a key role in hepatitis B virus (HBV) infection and replication. Currently, no effective intervention is available to inhibit the function of HBx. Additionally, the interaction mechanisms between HBx and its interacting proteins need to be further elucidated. Previously, we obtained mAbs 2A7 and 2A2 that can efficiently recognize HBx. The epitope recognized by 2A7 is located within the region where HBx interacts with DDB1. HBx can promote the degradation of intracellular antiviral proteins via its interaction with DDB1. 2A7 can block the interaction between HBx and DDB1. The epitope of 2A2 is in the negative regulatory region of HBx. The role of this region in HBV infection and replication is unclear. We obtained the nucleic acid coding sequences of the heavy chain and light chain variable regions of 2A7 and 2A2, and constructed and expressed single-chain variable fragments (scFv). In this study, we will modify and optimize the scFvs based on 2A7 and 2A2 mAbs in vitro, so that they can be efficiently expressed in cells as intracellular antibodies. Meanwhile, we will also explore the way of introducing 2A7 and 2A2 mAbs into cells mediated by membrane-penetrating peptides. We will study the possibility and molecular mechanism of inhibiting HBV infection and replication by using intracellular antibodies of HBx, discover new HBx interaction proteins, and further elucidate the function of HBx in HBV infection and replication. The research of this project will provide theoretical basis and technical methods for the development of HBx-targeting new anti-HBV drugs.