Seifer M, Heermann K H, Gerlich W H
Department of Medical Microbiology, University of Göttingen, Federal Republic of Germany.
Virology. 1990 Nov;179(1):287-99. doi: 10.1016/0042-6822(90)90297-5.
Permanent mouse fibroblast LTK- cells were transfected with dimeric hepatitis B virus (HBV) DNA linked to the simian virus 40 (SV40) early promoter/enhancer. Many clones stably expressed high levels of polyadenylated RNAs encoding hepatitis B surface (HBs) proteins (2.1 kb), HBe protein (3.6 kb), and HBx protein (0.6 kb). Although a chimeric RNA (4.0 kb) probably starting from the SV40 promoter was also synthesized, transcription of viral RNAs was predominantly directed by HBV promoters and its terminator. In contrast to HBV-transfected liver cells, the fibroblasts expressed only pregenomic 3.6-kb transcripts starting 5' to, but not within, the precore sequence. Thus, no normal core protein could be synthesized, but the cells expressed and secreted HBe protein of heterogeneous size. Small and middle HBs proteins were strongly expressed, while large HBs protein was almost absent. HBx mRNA expression was more efficient in mouse fibroblasts than in human hepatoma cells and 18-kDa HBx protein was exclusively detected in purified nuclei. Expression of HBe, small and middle HBs, and HBx proteins apparently does not require hepatic factors. Underexpression of HBc mRNA and large HBs mRNA suggests that activity of their promoters depends on cell-type-specific transcription factors.
将与猿猴病毒40（SV40）早期启动子/增强子相连的二聚体乙型肝炎病毒（HBV）DNA转染到永久性小鼠成纤维细胞LTK-中。许多克隆稳定表达高水平的编码乙型肝炎表面（HBs）蛋白（2.1 kb）、HBe蛋白（3.6 kb）和HBx蛋白（0.6 kb）的多聚腺苷酸化RNA。尽管也合成了一种可能从SV40启动子起始的嵌合RNA（4.0 kb），但病毒RNA的转录主要由HBV启动子及其终止子指导。与转染HBV的肝细胞不同，成纤维细胞仅表达起始于前核心序列5'端而非其内部的前基因组3.6 kb转录本。因此，无法合成正常的核心蛋白，但细胞表达并分泌大小不均一的HBe蛋白。中小HBs蛋白强烈表达，而大HBs蛋白几乎缺失。HBx mRNA在小鼠成纤维细胞中的表达比在人肝癌细胞中更有效，并且在纯化的细胞核中仅检测到18 kDa的HBx蛋白。HBe、中小HBs和HBx蛋白的表达显然不需要肝脏因子。HBc mRNA和大HBs mRNA的低表达表明其启动子的活性取决于细胞类型特异性转录因子。
