State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China.
Microbiol Res. 2018 Jan;206:177-185. doi: 10.1016/j.micres.2017.10.010. Epub 2017 Oct 27.
Haemophilus parasuis is an opportunistic pathogen localized in the upper respiratory tracts of pigs, its infection begins from bacterial survival under complex conditions, like hyperosmosis, oxidative stress, phagocytosis, and sometimes antibiotics as well. The two-component signal transduction (TCST) system serves as a common stimulus-response mechanism that allows microbes to sense and respond to diverse environmental conditions via a series of phosphorylation reactions. In this study, we investigated the role of TCST system CpxRA in H. parasuis in response to different environmental stimuli by constructing the ΔcpxA and ΔcpxR single deletion mutants as well as the ΔcpxRA double deletion mutant from H. parasuis serotype 4 isolate JS0135. We demonstrated that H. parasuis TCST system CpxRA confers bacterial tolerance to stresses and bactericidal antibiotics. The CpxR was found to play essential roles in mediating oxidative stress, osmotic stresses and alkaline pH stress tolerance, as well as macrolide resistance (i.e. erythromycin), but the CpxA deletion did not decrease bacterial resistance to abovementioned stresses. Moreover, we found via RT-qPCR approach that HAPS_RS00160 and HAPS_RS09425, both encoding multidrug efflux pumps, were significantly decreased in erythromycin challenged ΔcpxR and ΔcpxRA mutants compared with wild-type strain JS0135. These findings characterize the role of the TCST system CpxRA in H. parasuis conferring stress response tolerance and bactericidal resistance, which will deepen our understanding of the pathogenic mechanism in H. parasuis.
副猪嗜血杆菌是一种机会致病菌，定殖于猪的上呼吸道，其感染始于在复杂条件下细菌的存活，如高渗、氧化应激、吞噬作用，有时还包括抗生素。双组分信号转导（TCST）系统作为一种常见的刺激-反应机制，使微生物能够通过一系列磷酸化反应感知和响应各种环境条件。在这项研究中，我们通过构建 H. parasuis 血清型 4 分离株 JS0135 的ΔcpxA 和ΔcpxR 单缺失突变体以及ΔcpxRA 双缺失突变体，研究了 TCST 系统 CpxRA 在副猪嗜血杆菌中对不同环境刺激的作用。结果表明，副猪嗜血杆菌 TCST 系统 CpxRA 赋予细菌对压力和杀菌抗生素的耐受性。发现 CpxR 在介导氧化应激、渗透压应激和碱性 pH 应激耐受以及大环内酯类耐药（如红霉素）方面发挥重要作用，但 CpxA 缺失不会降低细菌对上述应激的抗性。此外，我们通过 RT-qPCR 方法发现，与野生型菌株 JS0135 相比，在红霉素胁迫的ΔcpxR 和ΔcpxRA 突变体中，编码多种药物外排泵的 HAPS_RS00160 和 HAPS_RS09425 显著减少。这些发现描述了 TCST 系统 CpxRA 在副猪嗜血杆菌中赋予应激反应耐受和杀菌抗性的作用，这将加深我们对副猪嗜血杆菌致病机制的理解。
