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目的:探究全局性转录调控因子CodY在单核细胞增生李斯特菌(Listeria monocytogenes,Lm)鞭毛运动和细菌毒力方面的作用。方法:通过同源重组的方法敲除Lm染色体上CodY的编码基因codY并成功构建缺失菌株的回复菌株;利用平板泳动法观测鞭毛运动的变化,RT-qPCR检测与鞭毛运动相关基因的转录表达;比较野生型菌株EGDe与CodY缺失菌株对细菌溶血活性、棉铃虫幼虫的半致死剂量和主要的毒力因子LLO和毒力基因调控蛋白PrfA转录表达的影响。结果:同野生型菌株相比,CodY缺失菌株鞭毛运动和相关基因,以及主要的毒力因子LLO和PrfA的转录表达显著降低(P≤0.01),溶血活性显著降低(P≤0.01),对棉铃虫幼虫的半致死剂量上升了5.8倍。结论:CodY在Lm鞭毛运动和细菌毒力调控方面具有重要作用。
AIM: To investigate the role of the global transcriptional regulator CodY in flagellar motility and bacterial virulence in Listeria monocytogenes (Lm). Methods: CodY encoding gene codY was knocked out by homologous recombination and the recombinant strain was successfully constructed. The changes of flagella motility were observed by platelet electrophoresis. The transcriptional expression of flagellar motility related genes was detected by RT-qPCR . The effects of EGDe and CodY deletion strains on the hemolysis activity, the lethal dose of the H. armigera larva and the expression of the major virulence factors LLO and PrfA of the virulence gene were compared. Results: Compared with the wild-type strain, the transcriptional expression of flagellar motility and related genes and the major virulence factors LLO and PrfA in CodY-deficient strains were significantly decreased (P≤0.01) and hemolytic activity was significantly reduced (P≤0.01) The lethal dose of insects larvae increased by 5.8 times. Conclusion: CodY plays an important role in the regulation of Lm flagella motility and bacterial virulence.