鸭致病性大肠杆菌外膜蛋白型研究

Determination of the Outer Membrane Protein(OMP) Patterns of Pathogenic E. coli Isolated from Ducks

测定了从我国分离到的130株鸭病原性大肠杆菌外膜蛋白型（Outer membrane protein patterns,OMP型）,其中O93、O92、O78和O76优势血清型53株,O46等30个其他血清型分离株77株,这些分离株共产生了4个OMP型,其中OMP-1型81株,占62.3%（81/130）,覆盖O93、O92、O78和O76等29个血清型,占85.3%（29/34）,为主要的OMP型;根据GenBank中大肠杆菌K-12外膜蛋白A基因（ompA）的核苷酸序列设计引物,从9株优势血清型和1株O46血清型的鸭大肠杆菌中分别扩增得到ompA基因,进行序列测定及分析,发现优势血清型9个菌株的ompA均由1 171个碱基组成,均只有1个大的开放阅读框（ORF）,长1 053 bp,编码由350个氨基酸组成的前外膜蛋白A（pro-OmpA）,前21个氨基酸残基组成信号肽,成熟的OmpA由329个氨基酸残基组成;O46菌株的ORF全长1 041 bp,在400-411 bp位缺失了12个碱基,成熟的OmpA由325个氨基酸残基组成;10个鸭致病性E.coli的ompA基因核苷酸序列高度同源,相似性达95.8%~100%。

The outer membrane patterns of 130 pathogenic E.coli strains isolated from ducks of 3 provinces or municipal cities in southwest China were determined in this study.Among these 130 strains,53 isolates belonged to prominent serotype O93,O92,O78 and O76,while 77 strains were serotype O46 and other serotypes.There were 4 different OMP patterns among all strains tested.62.3%（81/130） of strains that belong to 29 serotypes were identified to be OMP-1,including O93,O92,O78 and O76,suggesting that OMP-1 was the main OMP pattern.Subsequently,a pair primers for amplification of ompA gene was designed according to sequence of the E.coli K-12 available in GenBank.The ompA gene were then amplified and sequenced from 9 prominent serotype strains and 1 serotype O46 strain.Sequence analysis revealed that the ompA gene of all 9 prominent serotype strains was 1 171 bp long and composed of only one large open reading frame（ORF） with a size of 1 053 bp,which encoded a protein consist of 350 amino acids,pro-ompA.The first 21 amino acids encoded a signal peptide and the mature OmpA protein was composed of 329 amino acids.The ORF of ompA gene from O46 serotype strain was 1 041 bp in length with a 12 bp depletion at the site of 400-411 bp compared to other serotype strains,and the mature OmpA protein contained 325 amino acids.It was also found that the nucleotide sequences of ompA genes hared high homology with an identity ranging from 95.8% to 100% among 10 pathogenic E.coli strains from ducks.