Ponnazhagan S, Woody M J, Wang X S, Zhou S Z, Srivastava A
Department of Medicine, Indiana University School of Medicine, Indianapolis 46202, USA.
J Virol. 1995 Dec;69(12):8096-101. doi: 10.1128/JVI.69.12.8096-8101.1995.
The pathogenic human parvovirus B19 contains a promoter at map unit 6 (B19p6) of the viral genome, expression from which is largely restricted to human cells in the erythroid lineage, whereas a putative promoter at map unit 44 (B19p44) is inactive during a natural viral infection. Although nonerythroid human cells, such as HeLa and KB, allow expression from the B19p6 promoter but not from the B19p44 promoter following DNA-mediated transfection, little expression from the B19p6 promoter occurs following recombinant virus infection (S. Ponnazhagan, X.-S. Wang, M.J. Woody, F. Luo, L.Y. Kang, M.L. Nallari, N.C. Munshi, S.Z. Zhou, and A. Srivastava, submitted for publication). However, significant expression from the B19p6 promoter as well as the B19p44 promoter could be detected in a human 293 cells line that expresses the adenovirus early gene products, suggesting that coinfection with adenovirus might mediate transcriptional transactivation of the B19 promoters in nonpermissive cells. Expression of the firefly luciferase reporter gene from the B19 promoters was evaluated either following plasmid transfection or following infection with the recombinant adeno-associated virus type 2 vectors. Both B19p6 and B19p44 promoters could be transactivated by coinfection with adenovirus in nonpermissive human cells, although the extent of transactivation of the B19p44 promoter was significantly lower than that of the B19p6 promoter. Expression of the adenovirus E1A proteins was necessary and sufficient for the observed transactivation of the B19 promoters. These studies further illustrate that the underlying molecular mechanisms of transactivation of parvovirus promoters in general by the adenovirus early proteins have similarities with those of the well-documented transactivation of the adeno-associated virus type 2 promoters.
致病性人细小病毒B19在病毒基因组的图位单位6(B19p6)处含有一个启动子,该启动子的表达在很大程度上局限于红系谱系的人类细胞,而图位单位44(B19p44)处的一个假定启动子在自然病毒感染期间是无活性的。尽管非红系人类细胞,如HeLa和KB细胞,在DNA介导的转染后允许B19p6启动子表达,但不允许B19p44启动子表达,然而在重组病毒感染后,B19p6启动子几乎不表达(S. Ponnazhagan、X.-S. Wang、M.J. Woody、F. Luo、L.Y. Kang、M.L. Nallari、N.C. Munshi、S.Z. Zhou和A. Srivastava,已提交发表)。然而,在表达腺病毒早期基因产物的人293细胞系中,可以检测到B19p6启动子以及B19p44启动子的显著表达,这表明与腺病毒的共感染可能介导非允许细胞中B19启动子的转录反式激活。在质粒转染后或用重组2型腺相关病毒载体感染后,评估了来自B19启动子的萤火虫荧光素酶报告基因的表达。在非允许性人类细胞中,与腺病毒共感染可使B19p6和B19p44启动子反式激活,尽管B19p44启动子的反式激活程度明显低于B19p6启动子。腺病毒E1A蛋白的表达对于观察到的B19启动子的反式激活是必要且充分的。这些研究进一步表明,腺病毒早期蛋白一般反式激活细小病毒启动子的潜在分子机制与2型腺相关病毒启动子的反式激活机制相似,这一点已有充分记录。