Mawassi M, Mietkiewska E, Gofman R, Yang G, Bar-Joseph M
S. Tolkowsky Laboratory, Department of Virology, Volcani Center, Bet Dagan, Israel.
J Gen Virol. 1996 Sep;77 ( Pt 9):2359-64. doi: 10.1099/0022-1317-77-9-2359.
The complete, 19,226 nt sequence of the RNA genome from VT, a seedling yellows strain of citrus tristeza virus (CTV), was determined and found to have a genome organization identical with that of the previously determined CTV-T36 isolate, except that ORF 1 of CTV-VT was 70 nt shorter due to two widely separated 18 nt deletions. Sequence comparison of CTV-VT and CTV-T36 revealed approximately 89% identity throughout the ten 3' ORFs, but only 60-70% identity throughout ORF 1. The 5' nontranslated regions were only 60% identical whereas the 3' nontranslated regions were 97% identical. The transition between regions of similarity and deviation was gradual, suggesting that the sequence similarities and differences compared to CTV-T36 were unlikely to have arisen from a recent recombination event between a close T36 relative and a distantly related CTV isolate. This is the first attempt to compare in detail the variation between the genomes of two strains of a member of the closterovirus group. The observed deviation between the large RNA genomes of the two CTV strains is greater than that among different viruses of most other groups, raising the question of how to define the taxonomy of these viruses.
测定了柑橘衰退病毒（CTV）幼苗黄化株系VT的RNA基因组完整的19226个核苷酸序列，发现其基因组结构与先前测定的CTV-T36分离株相同，只是CTV-VT的ORF 1因两个相距较远的18个核苷酸的缺失而短了70个核苷酸。CTV-VT和CTV-T36的序列比较显示，在十个3' ORF中整体约有89%的同一性，但在整个ORF 1中只有60-70%的同一性。5'非翻译区只有60%的同一性，而3'非翻译区则有97%的同一性。相似性区域和差异区域之间的过渡是渐进的，这表明与CTV-T36相比，序列的相似性和差异不太可能源于T36的近缘亲属与远缘相关的CTV分离株之间最近的重组事件。这是首次详细比较黄化病毒组成员的两个株系基因组之间的变异。观察到的两个CTV株系的大RNA基因组之间的偏差大于大多数其他组不同病毒之间的偏差，这就提出了如何定义这些病毒分类学的问题。
