Modulation of virulence genes by the two-component system PhoP-PhoQ in avian pathogenic Escherichia coli
Modulation of virulence genes by the two-component system PhoP-PhoQ in avian pathogenic Escherichia coli
复制标题
双组分系统 PhoP-PhoQ 对禽致病性大肠杆菌毒力基因的调节
DOI：
10.1515/pjvs-2016-0005
复制
发表时间：
2016-01-01
影响因子：
0.8
通讯作者：
Qi, Kezong
中科院分区：
文献类型：
--
作者：
Tu, Jian;Huang, Boyan;Qi, Kezong
禽致病性大肠杆菌（APEC）感染是养禽业面临的一个重要问题。PhoP-PhoQ是一个调控APEC毒力基因的双组分系统。在这项研究中，我们构建了菌株，缺乏PhoP或PhoQ基因，以评估亚太经合组织致病性的PhoP-PhoQ双组分系统的调节。通过Red同源重组法构建了PhoP突变株AE18、PhoQ突变株AE19和PhoP/PhoQ突变株AE20。采用游泳平板法检测APEC菌株的运动能力，活菌计数法检测APEC菌株对鸡胚成纤维细胞的粘附和侵袭能力，Real-Time PCR法检测APEC菌株毒力基因mRNA的表达。我们首先证实AE18、AE19和AE20是从野生型AE17菌株成功构建的。与AE17相比，AE18、AE19和AE20的运动性分别显著降低70.97%、83.87%和37.1%。此外，与AE17相比，AE18、AE19和AE20显示CEF细胞粘附分别显著降低63.11%、65.42%和30.26%，CEF细胞侵袭分别显著降低59.83%、57.82%和37.90%。与AE17相比，AE18中sodA、polA和iss的转录水平显著降低，而AE19中fimC和iss的转录水平显著降低。我们的研究结果表明，删除PhoP或PhoQ抑制APEC的侵袭和粘附CEF细胞，并显着降低APEC毒力通过调节毒力基因的转录。
Avian pathogenic Escherichia coli (APEC) infections are a very important problem in the poultry industry. PhoP-PhoQ is a two-component system that regulates virulence genes in APEC. In this study, we constructed strains that lacked the PhoP or PhoQ genes to assess regulation of APEC pathogenicity by the PhoP-PhoQ two-component system. The PhoP mutant strain AE18, PhoQ mutant strain AE19, and PhoP/PhoQ mutant strain AE20 were constructed by the Red homologous recombination method. Swim plates were used to evaluate the motility of the APEC strains, viable bacteria counting was used to assess adhesion and invasion of chick embryo fibroblasts, and Real-Time PCR was used to measure mRNA expression of virulence genes. We first confirmed that AE18, AE19, and AE20 were successfully constructed from the wild-type AE17 strain. AE18, AE19, and AE20 showed significant decreases in motility of 70.97%, 83.87%, and 37.1%, respectively, in comparison with AE17. Moreover, in comparison with AE17, AE18, AE19, and AE20 showed significant decreases of 63.11%, 65.42%, and 30.26%, respectively, in CEF cell adhesion, and significant decreases of 59.83%, 57.82%, and 37.90%, respectively, in CEF cell invasion. In comparison with AE17, transcript levels of sodA, polA, and iss were significantly decreased in AE18, while transcript levels of fimC and iss were significantly decreased in AE19. Our results demonstrate that deletion of PhoP or PhoQ inhibits invasion and adhesion of APEC to CEF cells and significantly reduces APEC virulence by regulating transcription of virulence genes.