中国1995-2004年鸡传染性支气管炎病毒地方分离株膜蛋白基因的遗传变异分析

Genetic Variations of Membrane Gene of Infectious Bronchitis Virus Strains Isolated in China between 1995 and 2004

应用RT-PCR方法扩增到了我国1995-2004年20株IBV现地分离株的膜蛋白（Membrane,M）基因片段。序列测定表明,20株IBV分离株M基因开放阅读框由672-681bp组成,编码由223-226个氨基酸残基组成的多肽。与我国分离株LX4相比,M基因推导氨基酸序列的变异主要发生在2-17位、221-223位,其中4-6位存在氨基酸的插入和缺失,导致IBV毒株间M蛋白糖基化位点的差异。与GenBank中34株IBV参考毒株M蛋白基因推导氨基酸序列进行比较和分析,系统进化关系显示54株IBV毒株分属于5个进化群。我国IBV分离株M基因在进化关系上较为独立,主要分布在第Ⅱ群和第Ⅳ群,其中第Ⅱ群分离株和中国台湾毒株进化关系密切。此外,参考IBV国内分离株S1基因及N基因系统发育进化树的研究结果,并与M基因进行比较,表明我国IBV也存在着基因重组现象,尤其是疫苗毒和流行毒之间的重组。

Membrane （M） protein genes of 20 infectious bronchitis virus （IBV） strains isolated in China between 1995 and 2004 were sequenced and analyzed. The M genes of twenty isolates were composed of 672 to 681 nucleotides, encoding polypeptides of 223 to 226 amino acid residues. Variations of the deduced amino acids of M gene mainly occurred at positions 2 to 17 and 221 to 233, comparing with that of the IBV strain LX4. There were deletions or insertions in the M gene of Chinese isolates at amino acid position 2 to 6, leading to the loss or gain of a glycosylation site. Phylogenetic tree based on amino acid sequences of M genes from 20 Chinese isolates and 34 reference strains showed that they were classified into five distinct clusters. Most of the Chinese IBV strains were included in clusters Ⅱ and Ⅳ, forming distinct groups. The isolates in cluster Ⅱ showed a close evolutionary relationship with Taiwan isolates. Furthermore, recombination especially the recombination between field isolates and vaccine strains had been observed while comparing the phylogeny of M genes with those of S1 and N genes.