【作者】 李明乾； 陈孝学； 蔡顺风； 苘娜娜； 金伟； 鲁兴萌；

【Author】 LI Ming-Qian CHEN Xiao-Xue CAI Shun-Feng MAN Na-Na JIN Wei LU Xing-Meng (Lab. Invertebrate Pathology,College of Animal Sciences,Zhejiang University,Hangzhou 310029,China)

【机构】 浙江大学动物科学学院无脊椎动物病理学研究室；

【摘要】 家蚕传染性软化病病毒(Bombyx mori infectious flacherie virus,BmIFV)是单链正义RNA病毒,属于Iflavirus。虽然类似病毒性软化病的情况在许多国家也有报道,但GenBank只有唯一的一条日本株BmIFV全长9650bp,编码3085个氨基酸的多聚蛋白全基因组序列。本研究利用5′和3′cDNA末端快速扩增和常规RT-PCR技术成功获得了中国株BmIFV的全基因组(序列号EU868609),除3′端poly(A)全长9665bp,编码3085个氨基酸的多聚蛋白。全基因组序列分析表明:中国株与日本株BmIFV的核苷酸和氨基酸的识别率为99%,其中结构蛋白VP1、VP3、VP4和前导蛋白(L蛋白)的识别率为100%。依据RNA依赖性RNA聚合酶保守序列构建进化树显示:两种病毒有极高的亲缘关系。对Iflavirus属不同地域的同种病毒的基因序列比较发现:Iflavirus属不同地域的同种病毒的变异率低,可能与昆虫未健全免疫系统有关。小RNA病毒两端的非编码区对病毒的复制和翻译具有极其重要的作用。而BmIFV5′非编码区是目前发现的Iflavirus属病毒中序列最短的一种,对其二级结构的预测和序列比对发现其可能也具有内部核糖体进入位点功能。BmIFV中国株全基因组的获得和少变异的特点,为开展小RNA病毒的功能基因组学研究,以及BmIFV的分子流行病学提供了良好的基础。更多还原

【Abstract】 Bombyx mori infectious flacherie virus(BmIFV) is single-strand positive-sense RNA virus which belongs to Iflavirus. Although there are many reports about the BmIFV in many countries,there is only one Japanese BmIFV genome in Genbank which includes 9650 nucleotides and codes a polyprotein which comprises of 3085 amino acids. We succeeded to clone the whole genome of BmIFV isolated in China(EU 868609) by 5’ and 3’ rapid amplification of cDNA ends(RACE) and normal RT-PCR. The total genome composes of 9665 nucleotides excluding the 3’ poly(A) tail and codes the polyprotein which comprises of 3085 aa. The whole genome sequence analysis shows:BmIFVs isolated in China and Japanese were 99% identical in nucleotide and amino acid sequences. While the identities of three structure proteins(VP1,VP3 and VP4) and L protein are 100%. Phylogenetic analysis based on conserved domains of RdRps show that the two virus have absolutely high relationship. The aberration rate of the same kind of virus of Iflavirus in different areas is low by comparison with the genome sequences of them.This may be the cause of the unsound immune system of the insects. The non-coding regions(NCRs) of picornavirus play an important role in the virus replication and translation. The 5′ NCR of BmIFV is the shortest among the found Iflavirus virus,and the forecast of its secondary structure and sequence comparison prove that it maybe have the function of internal ribosome entry site(IRES) 。The gain of the whole genome of the BmIFV isolated in China and its weak mutation character established a great foundation to the analysis of the small RNA virus functional genome and the molecular epidemiology of BmIFV.更多还原