EseC, a translocon manipulates Edwardsiella tarda to induce host inflammatory responses by T3SS
ZHAO Kai-ying1, LIU Xiao-qi1, JING Ji-bo1, CAO Yu-jia1, ZHANG Nie-ke1, ZHANG Yi-di1, GAO Da-qing1, LU Cheng-ping2
1. School of Medicine, Southeast University, Nanjing 210009, China;
2. College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China
Abstract：T3SS is an important virulence factor of Edwardsiella tarda (Et), and EseC is a translocon of T3SS. We try to study the T3SS how to manipulate Et to induce host inflammatory responses after Et infected the host cells and tissues. Firstly, we construct ΔeseC gene mutant and its complementary strain from the wild type of Et.CD. Secondly, after the bacteria have infected RAW264.7 macrophages, bacterial colonies were counted on LB plates, and the cellular survival rates were inspected by CCK-8 method. We found that the reproductive rate of the wild type within macrophages increased obviously than that of the ΔeseC mutant, and the survival rate of the cells infected by the wild type was higher than that did by the mutant. The results indicated that the wild type caused more cells to die by its T3SS and to release more bacterial reconstituents than the mutant did. Moreover, we found that the necrosis rate of the macrophages infected by the wild type was more than that did by the mutant by flow cytometry (FCM). Results indicated that the wild type induced more cells necrosis by its T3SS and to release pro-inflammatory cytokines more than the mutant did. Thirdly, after the wild type and the mutant were injected into mice with an i.p. infection respectively, the CFUs/mL of the wild type in the liver, lungs, spleen and kidney of mice were significantly more than the ones of the ΔeseC strain, and the acute inflammatory responses in the tissues to the ΔeseC strain were more intensive than to wild type by HE staining, and the sizes of the liver, lungs, and spleen infected by the wild type were larger than the ones did by the mutant. The concentrations of IL-1β and TNF-α of inflammatory cytokines in the serums of the mice infected by the wild type were more than the ones did by the ΔeseC strain by ELISA. Results showed that the transcriptional levels of eseJ and eseE genes of the effector proteins of T3SS in the wild type were significantly more than those in the mutant by RT-PCR. Therefore, the eseC gene may affect Et to induce the inflammatory response in tissues and cells by T3SS.
[1] 陈爱平,江育林,钱冬,等.迟缓爱德华氏菌病[J].中国水产,2011,7:49-50. DOI:10.3969/j.issn.1002-6681.2011.07.020
[2] Pressley ME, Phelan PE, Witten PE, et al.Pathogenesis and inflammatory response to Edwardsiella tarda infection in the zebrafish[J]. Dev Comp Immunol,2005, 29(6):501-513 DOI:10.1016/j.dci. 2004.10.007
[3] Okuda J, Kiriyama M, Suzaki E, et al.Characterization of proteins secreted from system of a type III secretion of Edwardsiella tarda and their roles in macrophage infection[J].Dis Aquat Organ, 2009,84(2):115-121. DOI: 10.3354/dao02033
[4] Rao PS, Yamada Y, Tan YP, et al.Use of proteomics to identify novel virulence determinants that are required for Edwardsiella tarda pathogenesis[J]. Mol Microbiol,2004,53(2):573-586. DOI: 10.1111/j.1365-2958.2004.04123.x
[5] Gao D, Cheng J, Zheng E, et al.Eha, a transcriptional regulator of hemolytic activity of Edwardsiella tarda[J].FEMS Microbiol Lett,2014,353(2):132-140. DOI: 10.1111/1574-6968.12420
[6] 徐泽炎,李玉红,成静,等. eha基因调控迟缓爱德华菌抵抗巨噬细胞氧化杀菌作用[J].中国人兽共患病学报,2015,31(6):497-500. DOI:10.3969/j.issn.1002-2694.2015.06.001
[7] Gao D, Li Y, Xu Z, et al.The role of regulator Eha in Edwardsiella tarda pathogenesis and virulence gene transcription[J].Microb Pathog,2016,95:216-223. DOI: 10.1016/j.micpath.2016.03.010
[8] Figueira R, Holden DW.Functions of the Salmonella pathogenicity island 2 (SPI-2) type III secretion system effectors[J]. Microbiology,2012,158(5):1147-1161. DOI: 10.1099/mic.0.058115-0
[9] Xie HX, Yu HB, Zheng J, et al.EseG, an effector of the type III secretion system of Edwardsiella tarda, triggers microtubule destabilization[J].Infect Immun,2010,78(12):5011-5021. DOI: 10.1128/IAI.00152-10
[10] Xie HX, Lu JF, Zhou Y, et al.Identification and functional characterization of a novel Edwardsiella tarda effector Ese[J][J]. Infect Immun, 2015,83(4),1650-1660. DOI: 10.1128/IAI.02566-14
[11] Ashida H, Mimuro H, Sasakawa C.Shigella manipulates host immune responses by delivering effector proteins with specific role[J]. Front Immunol,2015,6:219-231. DOI: 10.3389/fimmu.2015.00219
2018, Vol. 34 
