【摘要】 根据GenBank中已经公布的鸡传染性支气管炎病毒株M基因序列,设计并合成1对特异引物,利用RT-PCR方法扩增出IBV河南分离株HN99株M基因的全长片段,然后进行克隆、测序,获得了长度为669 bp的HN99株M基因全序列,编码M蛋白222个氨基酸残基,其N端的前60 nt为前导序列,近N端含有1个潜在的N-糖基化位点,M基因编码的膜蛋白中含有9个高度保守的半胱氨酸;HN99株M蛋白点突变较多,且突变位点呈散在分布遍及整个ORF,主要表现为碱基的插入和缺失,在Glu 21~Leu 37,Ser 45~Ile 68,Pro 74~Phe 94位氨基酸的区域内形成3个跨膜区域,在39 Try~43 Thr,171 Ile~176 Pro,183 Arg~193 Ser位氨基酸处含有3个潜在的抗原位点;与GenBank中的11个国内外参考毒株相比,IBV-HN99株M基因核苷酸同源性为87.0%~90.3%,推导的氨基酸同源性为89.7%~94.2%;在系统发生进化树中,HN99株M基因与其他参考毒株属于不同的分支,亲缘关系均较远.更多还原

【Abstract】 The complete matrix glycoprotein gene of an infectious bronchitis virus strain HN99 isolated from Henan was amplified by RT-PCR method using a pair of specific primers designed according to the published Matrix glycoprotein gene sequence of IBV,The PCR products were cloned into the pMD18-T vector.Positive clones were identified by the restriction endonuclease analysis and PCR. The gene was sequenced and compared with 11 reference IBV strains from the GenBank. The results showed that the full length sequence of M gene of HN99 strain consisted of 669 bp,coding for predicated polypeptides of 222 amino acid residues.A leading sequence(signal peptide) about 60 nt and one glycosylated site in the N-terminal and nine highly conserved cysteine residues;there were many genic point mutations,and mutationsites diffuse throughout the whole ORF, insertions or deletions were mainly within the M gene of the IBV-HN99 strain,three specific transmembrane domains were located in regions from Glu 21 to Leu 37,from Ser 45 to Ile 68 and from Pro 74 to Phe 94 amino acids respectively,three potential antigen sites existed in regions at 39 Try～43 Thr,171 Ile～176 Pro and 183 Arg～193 Ser;analysis of the M gene sequences showed that it shared 87.0%～90.3% nucleotide homology and 89.7%～94.2% deduced amino acid sequence homology with the reference strains;evolution analysis indicated that IBV-HN99 strain was situated in the different branch of the phylogenetic tree based on the seque nces of M gene because of the far relation to other strains of IBV.These results suggested that IBV-HN99 strain be a new variant of IBV.更多还原