Ongus Juliette R, Roode Els C, Pleij Cornelis W A, Vlak Just M, van Oers Monique M
Laboratory of Virology, Wageningen University, Binnenhaven 11, 6709 PD Wageningen, The Netherlands.
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
J Gen Virol. 2006 Nov;87(Pt 11):3397-3407. doi: 10.1099/vir.0.82122-0.
Structure prediction of the 5' non-translated region (NTR) of four iflavirus RNAs revealed two types of potential internal ribosome entry site (IRES), which are discriminated by size and level of complexity, in this group of viruses. In contrast to the intergenic IRES of dicistroviruses, the potential 5' IRES structures of iflaviruses do not have pseudoknots. To test the activity of one of these, a bicistronic construct was made in which the 5' NTR of Varroa destructor virus 1 (VDV-1) containing a putative IRES was cloned in between two reporter genes, enhanced green fluorescent protein and firefly luciferase (Fluc). The presence of the 5' NTR of VDV-1 greatly enhanced the expression levels of the second reporter gene (Fluc) in Lymantria dispar Ld652Y cells. The 5' NTR was active in a host-specific manner, as it showed lower activity in Spodoptera frugiperda Sf21 cells and no activity in Drosophila melanogaster S2 cells.
对四种昆虫虹彩病毒RNA的5'非翻译区（NTR）进行结构预测，结果显示在这组病毒中存在两种潜在的内部核糖体进入位点（IRES），可根据大小和复杂程度加以区分。与双顺反子病毒的基因间IRES不同，昆虫虹彩病毒潜在的5' IRES结构没有假结。为了测试其中一种的活性，构建了一个双顺反子结构，即将含有假定IRES的狄斯瓦螨病毒1（VDV-1）的5' NTR克隆到两个报告基因——增强型绿色荧光蛋白和萤火虫荧光素酶（Fluc）之间。VDV-1的5' NTR的存在极大地提高了舞毒蛾Ld652Y细胞中第二个报告基因（Fluc）的表达水平。5' NTR以宿主特异性方式发挥活性，因为它在草地贪夜蛾Sf21细胞中活性较低，而在黑腹果蝇S2细胞中无活性。
