我国水稻条纹病毒一个强致病性分离物的RNA4序列测定与分析

SEQUENCE ANALYSIS OF RAN4 OF A SEVERE ISOLATE OF RICE STRIPE VIRUS IN CHINA

对我国水稻条纹病毒 (RiceStripeVirus,RSV)一个强致病性分离物 (辽宁PJ分离物 )的RNA4区段进行扩增、克隆和测序 ,其核苷酸序列全长 2 1 57bp。与已报道的日本T和M分离物及我国云南CX分离物的RNA4序列进行比较分析 ,结果表明 ,这 4个分离物可分为两组 ,其中 ,PJ、T和M分离物为一组 ,组内分离物之间 ,RNA4的毒义链 (vRNA4)及RNA4的毒义互补链 (vcRNA4)上的ORF的核苷酸一致性分别为 97 0 %和 97 0 %～ 97 5% ,5′末端和 3′末端非编码区的序列则完全一致。但PJ分离物与T分离物的亲缘关系更为密切 ,其基因间隔区 (IR)与T分离物的等长 ,核苷酸一致性为 93 0 % ,比M分离物的IR多了一段长1 9bp的插入序列 ,核苷酸一致性仅为 85 0 %。另一组为我国CX分离物 ,组与组之间 ,vRNA4及vcRNA4上的ORF的核苷酸一致性分别为 94 0 %和 92 5%～ 93 5% ,但在氨基酸水平上则没有明显的差异。CX分离物的IR与PJ分离物相比有一段长 84bp的插入序列 ,组间 ,IR的核苷酸一致性仅为 72 0 %～ 75 0 % ,5′末端非编码区的序列完全一致 ,但 3′末端非编码区有两个碱基的差异。这些结果表明 ,RSV在自然界的分子变异与其地理分布具有密切的关系。此外 。

RNA4 segment of a severe isolate of Rice stripe virus, isolated from Liaoning province and designated as PJ isolate, was amplified, cloned and sequenced. RNA4 of PJ isolate had 2157 nucleotide in length. When compared with RNA4 of T and M isolates of Japan and CX isolate of Yunnan province of China that had been previously reported, we found that these four isolates could be divided into two groups. PJ, T and M isolates shared 97.0% and 97.0%～97.5% identities in vORF4 and vcOFR4 at the nucleotide level, respectively and formed one group. The sequences in 5′ and 3′ terminal non\|encoding region were completely identical among these three isolates. In this group, PJ isolate was more closely related to T isolate than to M isolate. The length of intergenic region(IR4) of PJ isolate was as same as that of T isolate, and had 93.0% sequence identity. However, PJ IR4 had an insertion of 19bp in length compared with isolate M and had only 85.0% sequence identity. CX isolate belonged to another group, which shared only 94.0% and 92.5%～93.5% sequences identities in vORF4 and vcORF4 at the nucleotide level, respectively, even though there were not significant difference between these two group at the amino acid level. There was an insertion of 84bp in length in the IR4 of CX isolate compared with PJ isolate and the sequence identity between two group reached to 72.0%～75.0%. Even though no base variation occurred in 5′ terminal non\|coding region, there was two bases substitution in 3′terminal non\|coding region. These results showed that the isolates were grouped according to their geographical location. Additionally, highly consensus in 5′ and 3′ non\|encoding region suggested that these regions played an very important role in transcription and replication of viral genome. Finally, the molecular epidemiology and gene functions of Rice stripe virus were discussed in this paper.