Xin H W, Ji L H, Scott S W, Symons R H, Ding S W
Molecular Virology Laboratory, Institute of Molecular Agrobiology, National University of Singapore, Singapore 117604.
J Virol. 1998 Aug;72(8):6956-9. doi: 10.1128/JVI.72.8.6956-6959.1998.
We found that RNA 2 of the four ilarviruses sequenced to date encodes an additional conserved open reading frame (ORF), 2b, that overlaps the 3' end of the previously known ORF, 2a. A novel RNA species of 851 nucleotides was found to accumulate to high levels in plants infected with spinach latent virus (SpLV). Further analysis showed that RNA 4A is a subgenomic RNA of RNA 2 and encodes all of ORF 2b. Moreover, a protein species of the size expected for SpLV ORF 2b was translated in vitro from the RNA 4A-containing virion RNAs. The data support the suggestion that the SpLV 2b protein is translated in vivo. The 2b gene of ilarviruses, which is not encoded by alfamoviruses and bromoviruses, shares several features with the previously reported cucumovirus 2b gene; however, their encoded proteins share no detectable sequence similarities. The evolutionary origin of the 2b gene is discussed.
我们发现，迄今为止测序的四种等轴不稳环斑病毒属病毒的RNA 2编码一个额外的保守开放阅读框（ORF）2b，它与先前已知的ORF 2a的3'端重叠。在感染菠菜潜隐病毒（SpLV）的植物中发现了一种851个核苷酸的新型RNA物种大量积累。进一步分析表明，RNA 4A是RNA 2的亚基因组RNA，编码整个ORF 2b。此外，从含RNA 4A的病毒粒子RNA体外翻译出了大小符合SpLV ORF 2b预期的蛋白质物种。这些数据支持SpLV 2b蛋白在体内翻译的推测。等轴不稳环斑病毒属病毒的2b基因并非苜蓿病毒属病毒和雀麦花叶病毒属病毒所编码，它与先前报道的黄瓜花叶病毒2b基因有几个共同特征；然而，它们编码的蛋白质没有可检测到的序列相似性。本文讨论了2b基因的进化起源。
