广西1985年～2008年IBV分离株S1基因高变区Ⅰ和N基因的序列和系统进化分析

Sequence and phylogenetic analysis of S1 gene hypervariable region Ⅰ and N genes of infectious bronchitis viruses isolated in Guangxi province of China from 1985 to 2008

为了解广西传染性支气管炎病毒(IBV)的纤突蛋白S1基因高变区Ⅰ(HVRⅠ)和核(N)蛋白基因变异情况及S1和N基因变异的相关性,本研究应用RT-PCR方法扩增了广西1985年～2008年的21株IBV的S1基因HVRⅠ和N基因,并进行了克隆、序列测定及分析。结果发现:广西存在着多种基因型IBV流行;广西IBV分离株S1基因存在广泛的点突变和插入现象;N基因序列存在氨基酸替代现象。21株IBV中12株在S1基因HVRⅠ和N基因遗传进化树中均归属相同群,其余毒株却归属不同的群。2005年分离的GX-NN5存在基因重组现象。以上结果表明了广西IBV毒株存在基因突变和基因重组现象,S1和N基因的变异不完全平行,有些毒株间的S1和N基因差异很大。

To investigate genetic variations of S1 gene hypervariable region I （HVR I） and nucleocapsid （N） protein genes, S1 gene HVR I and N genes of 21 infectious bronchitis virus （IBV） strains isolated in Guangxi province of China between 1985 and 2008 were amplified by reverse transcriptase polymerase chain reaction （RT-PCR）, cloned and sequenced. The results showed that there were multi-genotypes IBVs prevailed in Guangxi province of China. Relatively high frequency of point mutations and insertions occurred within the S1 gene. Several amino acid substitutions were also found in the N protein gene sequences. Among all IBV strains, 12 belonged to the same genotype based on the deduced amino acid sequences of both S1 and N gene; others belonged to the different genotypes.