EHEC O157:H7 z3276基因缺失株构建及其生物学特性

发布时间：2018-04-23 11:02

本文选题：O + H　；参考：《微生物学通报》2017年12期

【摘要】：【目的】肠出血性大肠杆菌O157:H7是世界范围内重要的动物源性致病菌之一,可感染人。I型菌毛是多种致病性大肠杆菌(如肾盂肾炎型大肠杆菌等)可表达的一种黏附结构,与细菌吸附黏膜表面密切相关。然而,O157:H7 fim操纵子上几个核苷酸的缺失却导致其不能表达I型菌毛。BLAST比对结果表明O157:H7独有的开放阅读框z3276编码的氨基酸序列与其他大肠杆菌I型菌毛高度同源,这可能是对O157:H7不能表达I型菌毛的补偿机制,但确切功能尚不清楚。本文探究z3276基因的生物学功能。【方法】利用O157:H7 86-24参考菌株构建z3276基因缺失株(?z3276),并构建其互补株(C?z3276),进而比较亲本株、?z3276与C?z3276的生物学特性及对小鼠致病性差异。【结果】与亲本株相比,?z3276进入对数生长期的时间延后,在半固体琼脂平板上的迁移直径明显缩小,生物被膜形成能力显著减弱。?z3276对HEp-2细胞的黏附和侵袭能力并无明显变化,但对IPEC-J2细胞的侵袭能力明显减弱。在小鼠攻毒试验中,?z3276组排菌数量减少、排菌持续时间缩短。C?z3276各项特性均能回复到与亲本株一致的水平。【结论】z3276基因可能是O157:H7重要的毒力相关因子。
[Abstract]:[objective] Enterohemorrhagic Escherichia coli (O157:H7) is one of the most important animal pathogenic bacteria in the world. The infection of human type I fimbriae is an adhesive structure that can be expressed in many pathogenic Escherichia coli, such as pyelonephritis. It is closely related to the surface of mucous membrane adsorbed by bacteria. However, the deletion of several nucleotides on the O157: H7 fim operon resulted in its inability to express type I fimbriae. The results showed that the amino acid sequence encoded by O157:H7 unique open reading frame z3276 was highly homologous to other Escherichia coli type I pili. This may be a compensatory mechanism for the inability of O157:H7 to express type I fimbriae, but the exact function remains unclear. In this paper, the biological function of Z3276 gene was studied. [methods] using O157:H7 86-24 reference strain to construct Z3276 gene deletion strain, and to construct its complementary strain Cnz3276, and then to compare the biological characteristics and pathogenicity to mice between the parent strain of Z3276 and C?z3276. [ Results] compared with the parent strain, the time of entering logarithmic growth period of Z3276 was delayed. The migration diameter on the semi-solid Agar plate was significantly reduced, and the ability of biofilm formation was significantly decreased. The adhesion and invasion of HEp-2 cells were not significantly changed by .z3276, but the invasion ability of IPEC-J2 cells was significantly decreased. In the strain attack test of mice, the number of bacteria excreted in Z3276 group was decreased, and the duration of excretion was shortened. All the characteristics of Cnz3276 could return to the same level as the parent strain. [conclusion] Z3276 gene may be an important virulence related factor of O157:H7.
【作者单位】：江苏省农业科学院兽医研究所农业部兽用生物制品工程技术重点实验室国家兽用生物制品工程技术研究中心;省部共建国家重点实验室培育基地—江苏省食品质量安全重点实验室;江苏省动物重要疫病与人兽共患病防控协同创新中心;南京农业大学动物医学院;
【基金】：国家自然科学基金项目(No.31572503) 江苏省自主创新基金项目(No.CX(15)1060)~~
【分类号】：S852.612

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