近年来大肠杆菌K88ac菌毛的变异和生物学特性  

Variations and Biological Characterization of K88ac Fimbria of Escherichia coli of Late Years

作　　者：陈祥[1] 苗晓青[1] 刘静[1] 黄莉莉[1] 高崧[1] 焦新安[1] 刘秀梵[1] 

机构地区：[1]扬州大学农业部畜禽传染病学重点开放实验室,扬州225009

出　　处：《农业生物技术学报》2006年第5期757-762,共6页Journal of Agricultural Biotechnology

基　　金：教育部科学技术研究重点项目(No.204050);国家高技术研究与发展计划(863)项目(No.2003AA222141)资助

摘　　要：2000￣2005年,从猪大肠杆菌病(colibacillosis)中分离到一些表达K88菌毛的大肠杆菌(Escherichiacoli),这些分离株只与K88a因子单抗反应,而不与K88b、c和d因子单抗反应。分离的菌株(13/16)以O149为常见血清型,且全部拥有STb毒素基因,通过K88常规血清交叉吸收试验、SDS-PAGE和Western印迹,表明这些菌株不仅与K88ac参考菌株C83907制备的c因子血清反应,而且与以分离株SEC586制备且经K88ab、K88ac和K88ad参考菌株吸收后的血清也反应,表明这些分离株仍为K88ac大肠杆菌。对新近分离的SEC464、SEC525、SEC586、SEC799和EC910株及80年代我国分离的TM128株的K88主要亚单位结构基因faeG进行克隆、测序,发现新近分离株的faeG基因由846对核苷酸组成,编码菌毛主要亚单位的261个氨基酸及21个氨基酸的信号肽,比国内外报道的K88acFaeG亚单位(262个氨基酸)少了一个氨基酸,比K88ab、K88ad(264个氨基酸)少了3个氨基酸。TM128株的FaeG氨基酸序列与K88ac(M29375)的同源性为100.0%,SEC464、SEC525、SEC586、SEC799和SEC910株的FaeG亚单位氨基酸序列的同源性为97.7%￣99.6%,它们与K88ac的同源性为94.6%￣96.6%;与K88ab的同源性为90.0%￣91.6%;与K88ad的同源性为87.0%￣88.9%。结果表明新分离的K88ac大肠杆菌黏附素主要亚单位已发生了部分变异。Some Escherichia coil strains were isolated from swine colibacillosis in China during 2000 to 2005. They reacted with K88 a specific monoclonal antibody while without K88 b, c and d specific monoclonal antibodies in the slide agglutination test, respectively. O149 was common O semgroup of E. coli and 100.0%（16/16） strains possessed the genes of estlI in this study. These isolates were identified with K88ac variant by cross-absorbed rabbit antisera to K88ac fimbria. The apparent molecular weight of K88ac antigens purified from these isolates was about 26 kD in SDS-PAGE, and experienced a positive reaction with the rabbit antisera absorbed with K88ac reference strain by Western blot. The faeG gene was amplified from the genomic DNA of SEC464, SEC525, SEC586, SEC799 and SEC910 by PCR. Alignment analysis of major FaeG subunits of the K88ac fimbria of these isolates showed some differences in amino acid composition comparing with those of K88ac reference strains, implying that the antigenic differences between these isolates and reference strains were due to the mutation of major subunits of the fimbria. Comparison of the sequences of amino acids of the major units showed that the percent identity was 97.7% -99.6% among those isolates in amino acid sequences of major subunit FaeG, and 90.0%-91.6% comparing with K88ab reference strains, 94.6%-96.6% with K88ac reference strains, 87.0%-88.9% with K88ad reference strains, respectively. These results revealed that K88ac fimbrial antigens experienced some variations comparing with those of K88ac reference strains.

关 键 词：大肠杆菌 K88黏附素 单克隆抗体 faeG基因 

分 类 号：S188[农业科学—农业基础科学]