三株传染性法氏囊病病毒A节段全长基因组结构和编码蛋白的序列分析

用长距离RT PCR方法分别克隆了浙江地区传染性法氏囊病病毒 (IBDV)细胞致弱株HZ2、弱毒疫苗株JD1和野毒株ZJ2 0 0 0的A节段基因组全长 ,三毒株的A节段均长 32 59bp ,都包含两个相互重叠的开放阅读框架和两端的 5′ ,3′ 非编码区 (NCR)。它们在核苷酸和推导的四种病毒蛋白VP2、VP3、VP4、VP5的氨基酸水平上高度同源 ,并具有位于VP2高变区的特征性氨基酸H2 53、N2 79、T2 84、R330 ,这些氨基酸是弱毒株和几个强毒株的标志。野毒株ZJ2 0 0 0的高强毒力可能与VP2高变区和VP2 VP4剪切位点附近的几个突变有关。序列比较进一步支持VP2并非是决定IBDV毒力的唯一因素。不同毒力表型毒株的两端NCR序列高度保守提示NCR可能与IBDV毒力并不直接相关。另外 ,根据VP5在十种不同表型毒株中高度保守 ,作者提出了一种VP5与病毒毒力关系的推测

GENOMIC STRUCTURE AND PROTEINS SEQUENCE ANALYSIS OF FULL-LENGTH OF SEGMENT A OF THREE INFECTIONS BURSAL DISEASE VIRUSES

The full-length of segment A of three infectious bursal disease viruses (IBDV), including an attenuated strain HZ2, an attenuated vaccine strain JD1 and a virulent field isolate ZJ2000, were cloned by long RT-PCR and sequenced respectively. All the three results revealed the identity of IB-DV with two overlapping open reading frames (ORF) flanked by 5'- and 3'-noncoding regions(NCR) in 3259 bp long. The strains shared high identity with each other at nucleotide or deduced amino acid level, and also had four unique sites H253, N279, T284, R330 which are common in other attenuated and some classic or highly virulent strains. The virulent strain ZJ2000 had several key amino acid mutations located in hypervariant region of VP2 and near the VP2-VP4 cleavage site of polypeptide, which is probably related to the virulence. Sequence comparison supported that VP2 is not the sole determinant of the virulence. The highly conservation in 5'- and 3'-NCR of different strains indicated the NCR may be not responsible for the virulence. But the same conservation appeared in VP5 revealed another complex relationship between VP5 and the virulence.