鸡大肠埃希菌Ⅰ型菌毛pilA基因的克隆与序列分析

Cloning and Sequence Analysis of Type I Pili pilA Gene from Avian Pathogenic Escherichia coli

根据已公布的鸡大肠埃希菌pilA基因序列,在其保守区设计一对引物,以提取的3株鸡大肠埃希菌基因组DNA为模板,进行PCR扩增,获得3个克隆片段。经序列测定和分析表明,3株克隆片段均含有Ⅰ型菌毛pilA基因的全序列及完整的开放性阅读框架,片段大小为549bp,编码信号肽和结构蛋白;3株鸡大肠埃希菌分离菌株与其他菌株pilA基因之间核苷酸同源性为87.25%～98.36%,氨基酸同源性为87.36%～98.35%;系统进化分析表明,大肠埃希菌各菌株之间的pilA基因遗传相关性与其宿主来源及血清型之间没有显著的相关性;3株鸡大肠埃希菌I型菌毛间具有一定的结构相似性,并存在一定的共同抗原位点。

According to the published pilA gene sequence of avian Escherichia coli,a pair of primers were designed and synthesized.By using the genomic DNA of pathogenic Escherichia coli isolated from chickens as templates for polymerase chain reaction（PCR）,3 cloned fragments were gained.The sequence analysis indicated that 3 cloned fragments contained type I pili pilA gene which was 549 bp in length.By comparison,the homology of nucleotide and amino acid of pilA gene were 87.25%-98.36% and 87.36%-98.35% respectively between the isolates and other strains.The phylogenetic tree showed that the genetic correlation of pilA gene of avian Escherichia coli was not in strict association with the host source and the serotype.The analysis of antigenic sites and epitope of type I pili from 3 different isolates showed that they had some structure similarities,and they also had some common antigens.