建兰花叶病毒外壳蛋白基因和3＇UTR序列测定与分析

Sequencing and analysis of coat protein gene and 3′UTR of Cymbidium mosaic virus

采用单链构象多态性分析从建兰花叶病毒(Cymbidium mosaic virus,CyMV)的8个分离物筛选得到5个存在遗传变异的分离物,并测定了外壳蛋白(coat protein,CP)基因和3′非编码区(3′UTR)序列,经序列分析表明5个分离物与其他分离物间的CP核苷酸和氨基酸序列相似性分别为87.1%～99.9%和91.1%～99.6%,属于亚组A成员。CP基因不同片段受到正选择压力的作用不一样,C端受到负选择压力的作用不易发生变异,而N端受到正选择压力的作用容易发生变异。通过RNAsharpes软件分析3′UTR序列发现各分离物均形成带有Potexvirus属保守核苷酸序列"AC(C/T)TAA"的三叶草茎环结构,这种结构的功能可能与病毒RNA复制有关。

Five variant isolates of Cymbidium mosaic virus （CyMV） were screened by single strand conformation polymorphism （SSCP）. The coat protein gene and 3＇untranslated region （3~UTR） of the five isolates were se- quenced. The five CP genes share 87.1%--99.9% and 91.1%--99.6% similarity with other isolates reported in GenBank at the nucleotide and amino acid level, respectively. The five isolates belonged to subgroup A. The bioinformatics analysis confirmed the prevalence of positive selection at N-terminal regions of CP protein, and negative selection at C-terminal. A cloverleaf-like stem-loop structure harboring a conserved hexamer motif “AC （C/T）TAA” of Potexvirus was found at the 3＇UTR of all isolates according to the RNAsharpes, which may be im- portant to the duplication of RNA.