aroC基因对迟缓爱德华氏菌生物学特性及致病性的影响

Effect of aroC on biological characteristics and pathogenicity of Edwardsiella tarda

目的:探讨aroC基因在迟缓爱德华氏菌(Edwardsiella tarda,Et)致病过程中的作用。方法:采用自杀质粒同源重组方法制备Et的aroC基因缺失株(ΔaroC)和aroC的互补株(CΔaroC);通过生物膜形成、运动性、细胞黏附、斑马鱼致病性、组织细菌载量等实验,分析aroC对Et致病性相关的生物学功能的影响。结果:aroC基因的缺失不影响Et生长速度;与野生株和CΔaroC相比,ΔaroC的生物膜形成能力、运动能力、黏附及胞外吲哚生成能力均显著降低(P<0.05或<0.01);qRT-PCR结果显示,相比于野生株,ΔaroC鞭毛合成基因fliA和fliC的转录水平显著下降(P<0.01),但flgK、flgL和fliS基因的转录水平无明显变化(P>0.05);与野生株相比,感染ΔaroC的斑马鱼症状明显减轻、存活率高,且ΔaroC在小鼠肠道和肝脏中的定植数目显著减少(P<0.05或<0.01)。结论:aroC基因影响Et的运动性、生物膜形成、黏附性等,进而调控Et对宿主细胞的致病力。

Objective:To explore the role of aroC in the pathogenic process of Edwardsiella tarda(Et).Methods:TheΔaroC and CΔaroC of Et were constructed by homologous recombination of suicide plasmid.The effects of aroC on the biological function of Et were analyzed by biofilm formation,motility test,cell adhesion,zebrafish pathogenicity and bacterial colonization.Results:The deletion of aroC gene did not affect the growth rate of Et.Compared with the wild type and the CΔaroC,the biofilm formation,motility,adhesion and extracellular indole production ability ofΔaroC strain decreased significantly(P<0.05 or<0.01).The results of qRT-PCR showed that the transcriptional levels of flagellum synthesis genes fliA and fliC inΔaroC decreased significantly(P<0.01),but there was no significant change in the transcriptional levels of flgK,flgL and fliS genes(P>0.05).Compared with the wild type,symptoms were significantly reduced and higher survival rate were observed in zebrafish infected withΔaroC,and the colonization number ofΔaroC in intestine and liver of mice was decreased greatly(P<0.05 or<0.01).Conclusion:The aroC can affect the motility,biofilm formation and adhesion,and then regulate the pathogenicity of Et.