鼠伤寒沙门菌rtsB基因缺失株的构建及其生物学特性

Construction and characterization of the rtsB gene mutant strain of Salmonella typhimurium

【背景】鼠伤寒沙门菌(Salmonella typhimurium)是一种重要的人畜共患病原菌,严重危害养殖业及人类健康。调控蛋白在病原菌的生存及感染过程中发挥重要作用。【目的】构建鼠伤寒沙门菌调控基因rtsB缺失株和互补株,分析调控蛋白RstB对鼠伤寒沙门菌生物学特性和致病性的影响。【方法】利用Red同源重组的方法构建鼠伤寒沙门菌SAT52的rtsB基因缺失株,并利用互补质粒构建互补株。然后比较分析野生株SAT52、缺失株?rtsB和互补株C?rtsB的生长特性、运动性、生物被膜形成能力、黏附入侵能力、胞内存活能力及致病性的差异。【结果】缺失rtsB基因不影响SAT52的生长速度,但导致运动能力增强,生物被膜形成能力减弱。细胞感染试验结果表明,rtsB基因有助于鼠伤寒沙门菌对Hela细胞的黏附入侵及RAW264.7细胞内的存活。动物试验结果表明rtsB基因缺失显著降低鼠伤寒沙门菌的致病力。【结论】rtsB基因在鼠伤寒沙门菌感染过程中发挥重要作用,可为阐释鼠伤寒沙门菌的致病机制提供参考。

[Background] Salmonella typhimurium is an important zoonotic pathogen that causes economically devastating to livestock breeding and potential threats to human health. Regulatory proteins are involved in the regulation of the survival and infection of pathogens. [Objective] To analyze the effect of regulatory protein RstB on the biological characteristics and pathogenicity, the rtsB gene mutant and complemented strain of S. typhimurium were constructed and characterized. [Methods] We constructed the rtsB gene mutant strain and complemented strain of S. typhimurium SAT52 using the Red recombination system and complementary plasmid. Then we analyzed the growth characteristics, motility, biofilm formation, cells adhesion and invasion ability, and pathogenicity. [Results] The deletion of rtsB gene did not affect the growth rate of SAT52. However, the mutant strain showed significantly enhanced motility and decreased biofilm formation ability. Compared with the wild-type strain, the capacities of adherent to Hela cells and survival in RAW264.7 cells were significantly decreased for the mutant strain. The results of animal infection experiments showed that the virulence of mutant strain was attenuated. [Conclusion] The rtsB gene plays an important role in the pathogenesis of S. typhimurium infection, providing a certain basis for further understanding of the pathogenic mechanism of S. typhimurium. These data indicated that regulator RtsB plays an important role in the process of S. typhimurium infection, which would help us to comprehensive understand the pathogenic mechanism of S. typhimurium.