1.3倍乙型肝炎病毒全基因真核表达载体的构建及在HepG2细胞中的表达

Construction of recombinant eukaryotic expression plasmid containing 1.3-fold-overlength genome of HBV and its expression in HepG2 cells

目的 构建1.3倍全基因乙型肝炎病毒(HBV)真核细胞表达载体,观察其在HepG2细胞中的表达。方法 从pGEM—HBV载体上将约4.1kb的1.3倍HBV全基因克隆至真核表达载体pCDNA3.1的Hind Ⅲ位点,将构建的pHBV经Lipofectamine2000导入肝癌细胞系HepG2细胞中。分别在转染后24、48、72h测定HepG2上清液乙型肝炎表面抗原(HBsAg)、乙型肝炎e抗原(HBeAg)的表达,细胞内HBsAg、乙型肝炎核心抗原(HBcAg)免疫组织化学染色,Southern、northern杂交鉴定HBV的复制与表达。结果成功构建了1.3倍HBV全基因真核表达载体,转染后24、48、72h细胞上清液中HBsAg分别为5.36±0.25,13.42±1.24,7.52±0.43;HBeAg分别为9.16±0.32,22.75±1.49,15.96±1.03。免疫荧光结果显示转染后24 h细胞内HBsAg表达最强,主要呈胞浆内弥漫性分布,HBcAg为核浆型分布,以浆型为主。Southern、northern杂交均证实细胞内存在各种病毒复制中间体和特异的病毒复制转录物。结论 该表达载体可介导高水平病毒复制,其转染细胞可望成为一种新型的HBV 体外感染模型。

Objectives To transfer 1.3-fold-overlength genome of HBV expression plasmid into HepG2 cells, and observe the dynamic changes of viral replication as well as expression in the transfected cells. Methods 4.1 kb fragment of HBV genome, derived from pGEM-HBV, was cloned into Hind III site of the eukaryotic expression vector pCDNA3.1 to construct the recombinant plasmid pHBV. Then HepG2 hepatoma, cells were transfected with pHBV, using Lipofectamine2000 transfection reagent. After 24, 48, 72 hours, the levels of HBsAg and HBeAg in the supernatant of HepG2 cells were determined with Abbott ME1A Kit. Intracellular viral DNA and RNA were analyzed by Southern and northern blot hybridization. In addition, viral-specific proteins (HBsAg and HBcAg) were assayed by immunofluorescence staining. Results The expression vector pCDNA3.1 was constructed successfully. The levels of HBsAg were 5.36 ± 0.25, 13.42 ±1.24, 7.52±0.43, and the values of HBeAg were 9.16±0.32, 22.75± 1.49, 15.96±1.03 after 24, 48, 72 hours, respectively. All expected HBV replicative intermediates and specific transcripts were verified by Southern and northern blot analysis. The HBsAg-positive cells peaked after 24 hours, and then dropped slowly. HBsAg positive staining scattered in the cytoplasm, whereas HBcAg lied maily in the cytoplasm apart from nuclears. Conclusion This recombinant plasmid, which initiates viral replication efficiently in infected cells, is expected as a novel tool for investigating HBV replication in vitro.