【摘要】 以来自哈尔滨传染性法氏囊病病毒（ＩＢＤＶ） 强毒株（Ｈａｒｂｉｎ 毒株，Ｈ） 的基因组ＲＮＡ为模板，用反转录聚合酶链反应（ＲＴ－ ＰＣＲ） 的方法得到了其Ａ 节段的全长ｃＤＮＡ 片段，分５＇端（１ ６５９ｂｐ） 和３＇端（１ ４４４ｂｐ） 上下两段分别克隆到ｐＧＥＭＢ○Ｒ － Ｔ 载体上，测定了其核苷酸顺序，在长为３ １０１ ｂｐ 中含有两个阅读框ＯＲＦＡ１ 和ＯＲＦＡ２ ，分别编码１ ０１２ 个氨基酸的前体蛋白（ＶＰ２ － ４ －３） 和１４５ 个氨基酸的ＶＰ５，ＯＲＦＡ１ 和ＯＲＦＡ２ 有部分的重叠。将核苷酸序列及推测出的氨基酸序列与已报道的ＩＢＤＶ 血清Ⅰ型和Ⅱ型毒株的相应序列进行了比较，结果表明：Ｈ 毒株与其它血清Ⅰ型毒株之间，在核苷酸水平上存在２５ｂｐ － ２６７ｂｐ 的差异；在氨基酸水平上存在１７ ～４０ 个氨基酸的差异。在ＶＰ２ － ４ － ３ 内比较显示，Ｈ 毒株与Ｐ２ 、Ｃｕ－ １ 之间氨基酸的差异最小为１ ．７％ ，Ｈ 毒株与ＵＫ６６１ 之间氨基酸的差异最大为３ ．９ ％ 。变异主要发生在ＶＰ２ 的可变区（２０６ － ３５０ 位氨基酸） ，在Ｈ 毒株所特有的１２ 个氨基酸当中，该区就占５ 个，代表１ ．７６ ％ 的变异。ＶＰ４、ＶＰ３ 和ＶＰ５区各有更多还原

【Abstract】 By RT-PCR, the nucleotide sequences of the Harbin vvIBDV segment A, two ORFS for VP5 and precursor polyprotein were determined. The results showed that the cloned 3101bp segment A gene contains two overlapping open reading frames (ORFA1 and ORFA2). The large ORF of 3036bp encodes a polyprotein (VP2-4-3), whereas the small ORF is 435bp coding VP5. The deduced amino acid sequence of the Harbin strain was compared with those of other serotype 1 and 2 strains. The results showed that the sequence of the Chinese isolate, the Harbin strain, has variations for virulence and antigenecity. There are 25 to 267 nucleotide differences among segment A of Harbin strain and the other serotype I strains of IBDV. The polyprotein encoded by Harbin strain showed 17 to 40 amino acid differences from those of the other serotype I strains, with 12 substitutions unique to Harbin strain. The minimum amino acid divergence within polyprotein (1.7%) was observed among Harbin strain and P2, Cu-1 of serotype 1. The maximum amino acid difference was 3.9% observed between Harbin strain and Uk661. Within the 454 residues of VP2 of Harbin strain, there are 5 amino acid substitutions, representing 1.76% variation at the VP2 variable region between residues 206 to 350. Within the 267 residues of VP4, there are only 2 amino acid substitutions, representing 0.74% variation. Within the 289 residues of VP3, there are also 2 amino acid substitutions, representing 0.69% variation. Within the 145 residues of VP5, there are 2 amino acid substitutions, representing 1.38% variation. Harbin strain is neither similar to the vv strains from Europe, Japan and Israel nor to the variant strains from the United States and China Guanzhou. It is most closely related to the strains isolated earlier from Europe, however has distinct amino acid mutations in variable region, especially in two hydrophilic domains.更多还原