鸡致病性大肠杆菌I型菌毛交叉保护性研究及其结构基因FimA的序列分析

Cross protection of type I fimhriae vaccine of Avian pathogenic E.coli and nucleoutide sequence analysis of FimA gene

从山东省各地分离到 10 7株鸡致病性大肠杆菌 ,选择了其中 2株高致病性大肠杆菌 ,血清型分别为O78和O2 4,经增菌培养后提取菌毛制备为单价菌毛油乳苗 ,分别接种于 1日龄和 14日龄雏鸡 ,于 4周龄攻毒。结果二者之间有一定的交叉保护作用。根据Genbank收录的人源大肠杆菌I型菌毛FimA基因和P型菌毛papA基因序列 ,分别设计了 2对引物。通过PCR对上述 2株大肠杆菌进行扩增 ,结果只有FimA的一对引物扩增出相应的条带 ,经测序证明为FimA基因。papA基因的引物未扩出任何条带 ,证明这 2株大肠杆菌表达I型菌毛。通过对 2株大肠杆菌结构基因FimA进行分析 ,发现二者具有高度的同源性。本研究的目的是探讨菌毛亚单位之间的交叉保护性与其菌毛的结构基因之间是否存在相关性。

avian pathogenic E.coli isolates were isolated from shandong province.Two high pathogenic E.coli isolates were used for preparing the fimbriae vaccines.The chicken were vaccined on 1 day-old and 14 day-old,respectively.Then challenged via the air sac with E.coli(O_(78),O_(24))on 4 week-old chickens.The result was that the two isolates had certain cross protection.According to the published type 1 and type P nucleotide sequence from human E.coli,two pairs of primers were designed and synthesized.Two positive 549 bp products were amplificated by polymerse chain reaction(PCR) using the primers of FimA from the two strains.No amplification were obtained by using the primers of papA.There is high homology between FimA gene of the two isolates.The aim of the study is to make clear if there is relativity between cross protection and structural gene of fimbriae.