探討B型肝炎病毒剪接在HepG2-NTCP-C4感染模型中所扮演的角色

Abstract

慢性B型肝炎在全世界是一個重大的公共衛生議題，目前的治療未能有效地使慢性B型肝炎患者痊癒。在臨床研究上，HBV剪接與慢性B型肝炎具有高度的正相關性。探討HBV剪接在B型肝炎病毒感染中所扮演的角色，或許能提供HBV抗病毒藥物一個嶄新的靶點。先前的研究在肝癌細胞和小鼠中發現，轉染帶有剪接功能缺失的HBV質體，並不影響HBV病毒的複製。然而，利用人肝嵌合小鼠模型，感染由免疫缺陷小鼠所製造的HBV病毒，證實了HBV剪接對於建立有效的HBV感染是必要的。因為轉染模型只能模擬部分HBV的生命週期，在本篇研究中，肝癌細胞感染模型將被用來探討HBV剪接在HBV感染中所扮演的角色。研究結果指出，HBV基因組的複製、RNA轉錄與蛋白質轉譯並不仰賴HBV剪接。本篇研究與人肝嵌合小鼠模型的結果相異，可能源自於兩者研究模式上的差異，包括HBV質體、病毒來源與感染細胞株等因子。本篇論文將針對這些可能的因子做進一步的討論。

Chronic Hepatitis B infection remains a public health issue worldwide. Currently, there is still no effective therapy for chronic HBV infection. Clinical studies have found that chronic infection was associated with HBV spliced variants. Understanding the role of HBV splicing in viral life cycle should provide a new strategy for HBV treatment. Previously, it had been demonstrated that HBV splicing variants were not essential for viral replication in transfection model in vivo and in vitro. However, another study had revealed that splicing-deficient HBV, generated from SCID mice by in vivo transfection, failed to establish efficient HBV infection in humanized liver chimeric mice, suggesting the important role of HBV splicing. Because of the transfection model may not completely recapitulate the viral life cycle, in this study, we exploited an in vitro infection model to examine the role of HBV splicing. Splicing-deficient HBV virions, produced from hepatoma cell line Huh7 by in vitro transfection, were used to infect NTCP-overexpressing hepatoma cell line HepG2-NTCP-C4. Our data indicated that viral replication, transcription and translation have no difference between cells infected with WT or splicing-deficient HBV. In contrast to the restricted HBV infection in vivo, the successful HBV infection in vitro might due to several factors, such as replicons, virus-producing cells and virus-infected cells, which will be discussed in the thesis.