烟草花叶病毒(普通株中国分离物)及其弱毒疫苗-N14(番茄株)基因组侵染性cDNA核苷酸全序列测定与分析

Complete Nucleotide Sequences and Genome Structure of Two Chinese Tobacco Mosaic Virus Isolates Deduced from Full-length Infectious cDNA Clones

用双脱氧末端终止法对侵染性烟草花叶病毒普通株中国分离物 (TMV vulgar,ChineseIsolate,TMV Cv)和番茄株弱毒疫苗TMV N14(AttenuatedTMVvaccinestrain)基因组cDNAs的核苷酸全序列进行了测定 ,并分析和比较了其基因组的结构和特征。结果表明 :普通株基因组 (Genbank接收号 :AF16 5 190 )为 6 395个核苷酸 ;4个功能性开放阅读框架 (ORF) ,分别编码 12 6kD/ 183kD的复制酶、30kD运动蛋白和 17 6kD外壳蛋白。弱毒疫苗TMV N14基因组 (Genbank接收号 :AF15 5 5 0 7)为 6 384个核苷酸 ;5个功能性ORF分别编码 98 5kD/ 12 6kD/ 183kD的复制酶、2 7kD运动蛋白和 17 6kD外壳蛋白。与参比序列核苷酸和氨基酸序列比较 :普通株核苷酸序列同源率为99 4% ;推断的复制酶与运动蛋白分别有 5个和 2个氨基酸残基不同。TMV N14核苷酸序列同源率为 99 7% ;核苷酸位置 2 6 70～ 2 6 72和 5 6 32～ 5 6 34分别发生乳石 (Opal)突变 (UGA)和赭石 (Ochre)突变 (UAA) ;推断复制酶有13个氨基酸残基发生了变异。

The complete nucleotides of two Chinese tobacco mosaic virus (TMV) isolates,TMV Cv (vulgare strain) and TMV N14 (an attenuated virus originated from a tomato strain),were determined from their respective full\|length infectious cDNA clones and compared with published TMV sequences. The genome structure of TMV Cv contained 6395 nucleotides,in which four functional open reading frames (ORF),coding for replicase (126kD/183kD),movement protein(MP,30kD) and coat protein (CP,17.6kD) respectively,could be recognized. TMV N14 contained 6384 nucleotides in its genome. In contrast to TMV Cv,five functional ORFs encoding the replicase 98.5kD/126kD/183kD,MP(27kD) and CP(17.6kD),respectively,were detected in the TMV N14 genome. TMV Cv is 99% homologous to a Korean TMV isolate belonging to the vulgare strain at the nucleotide level. TMV N14 is 99% homologous to a highly virulent Japanese isolate TMV L (tomato strain) at the nucleotide level. In TMV N14,one opal nulation (UGA) occurred in the replicase gene and one ochre nutation (UAA) in the MP gene. The former mutation created a potential,additional ORF within the replicase gene,the latter reduced the size of the MP to 27kD. In addition,there were also 13 amino acid substitutions in the replicase gene of TMV N14 when compared to that of TMV L.Collectively, these changes may have significant implications in the attenuation of the virulence of TMV N14.