鼠伤寒沙门氏菌ybiH基因缺失株的构建及其生物学特性

Construction of a Salmonella typhimurium STΔybiH strain and its biological characteristics

摘要:

【背景】鼠伤寒沙门氏菌(Salmonella typhimurium)是一种重要的人兽共患病原菌，能够引起多种食源性疾病。ybiH基因在鼠伤寒沙门氏菌中的生物学功能尚未确定。【目的】构建鼠伤寒沙门氏菌ybiH基因的缺失株和回补株，研究ybiH基因在鼠伤寒沙门氏菌中的生物学功能。【方法】采用 λ-Red 同源重组系统构建鼠伤寒沙门氏菌CVCC541 ybiH 基因缺失株STΔybiH，同时构建该基因缺失株的回补株STΔybiH/pybiH，并对缺失株STΔybiH的生长特性、运动性、生化特性和毒力情况等生物学特性进行比较分析。【结果】与标准株和回补株相比，缺失株STΔybiH生长速率略快，而其运动性、生化特性、耐药性均无明显差别。但是，ybiH基因的缺失明显提高了鼠伤寒沙门菌对IEC-6细胞和RAW 264.7细胞的黏附力和侵袭力，qRT-PCR实验结果显示，缺失株中InvH基因的表达量明显提高，表明ybiH基因的缺失使鼠伤寒沙门氏菌的侵袭力也有所提高。此外，在胞内存活实验中，标准株与缺失株在胞内的增长率变化不明显，表明ybiH基因的缺失对沙门氏菌在RAW 264.7细胞中存活的影响不大。【结论】ybiH基因介导鼠伤寒沙门氏菌的黏附侵袭力，本文为进一步阐明ybiH基因的功能提供基础。

Abstract:

[Background] Salmonella enterica serovar Typhimurium (S. Typhimurium) is an important zoonotic pathogen that causes a variety of food-borne diseases. The biological function of ybiH gene in S. typhimurium has not been determined. [Objective] In order to define the pathogenicity of ybiH gene to S. typhimurium，the ybiH gene mutant and complementary strain of S. typhimurium were constructed and characterized. [Methods] In this paper, the mutant STΔybiH of S. typhimurium CVCC541 standard strain was successful constructed by λ-Red homologous recombination system. At the same time, its complementary strain STΔybiH/pybiH was successfully constructed. Then we analyzed the biological characteristics of growth characteristics, motility, biochemical properties and virulence. [Results] The results showed that the growth rate of STΔybiH was slightly faster than that of the standard strain and the complementary strain, but there was no significant difference in motility and biochemical characteristics. However, the deletion of ybiH gene significantly increased the adhesion and invasion of S. typhimurium to IEC-6 cells and RAW 264.7 cells. The results of qRT-PCR showed that the expression of InvH gene was significantly increased in the deletion strain. The results showed that the deletion of ybiH gene increased the invasiveness of S. typhimurium. In addition, the intracellular growth rate of the standard strain and the deletion strain did not change significantly in the intracellular survival experiment, indicating that the deletion of the ybiH gene had little effect on the survival of Salmonella in RAW 264.7 cells. [Conclusion] The ybiH gene mediates the adhesion and invasiveness of S. typhimurium, which provides a theoretical basis for further elucidating the function of ybiH gene.