禽传染性支气管炎病毒SAIBk株全基因组的分段克隆、测序及分析

Cloning and Sequence Analysis of the Genome of IBV SAIBk Strain Isolated in China

根据GenBank上公布的IBV基因组序列，经多重比较后设计19对引物，用RT-PCR方法对禽传染性支气管炎病毒致肾病变型分离株SAIBk株的全基因组进行了分段扩增、克隆和序列测定。测序结果表明：SAIBk株基因组序列全长27520 bp，A＋T的含量占61．74％，具有典型的冠状病毒基因组结构。基因组内碱基的插入和缺失主要分布在3 220-3470位、20560-20810位、25310-25600位和27150—27220位。与GenBank上公布的5株IBV基因组序列Beaudette、Mass41、Ca199、BJ、KQ6的同源率分别为87．2％、87．6％、87．2％、85．6％和87．5％。SAIBk株基因组不同区域的同源性分析结果表明，3＇UTR和5＇UTR是基因组中最为保守的区域，同源率在90．9％～97．7％，而S1基因是基因组中变异最大的区域，同源率在74．8％～83．2％。系统进化分析结果表明SAIBk株与国内分离株S14、LX4、BJ的亲缘关系较近。

According to the published genome sequences of infectious bronchitis virus （IBV） on GenBank, nineteen pairs of primers were designed and the genome of isolated SAIBk strain of IBV was amplified by RT-PCR. All the RT-PCR products were cloned into the pMD18-T vector and sequenced. The genome sequence of SAIBk strain was 27 520 bp in length. The ratio of A＋ T in the genome was 61.74%. Compared with the genome of Beaudette, Mass41, Cal99, BJ and KQ6, the similarity was 87.2%, 87.6%, 87.2%, 85.6% and 87.5%, respectively. The 3＇UTR and 5＇UTR were the most conservative region in the genome, the similarity was between 90.9% -97.7 %. The S1 gene have the most variations, the similarity was between 74.8 %-83.2 %. The phylogenetic analysis results showed that the SAIBk genome have a close relationship with S14,LX4,BJ strains which were isolated in China.