Study On Adhesion,Invasion And Intracellular Survival Ability Of Seven Intracellular Pathogens In Different Cell Lines

Salmonella,Shigella,and Brucella are common intracellular pathogens that can cause important zoonotic diseases,causing severe economic losses in the animal husbandry industry,and posing great threats to human health and public safety.Intracellular bacteria can reside in the host cell,and it is difficult for antibacterial drugs to enter the cell and play a role.In this study,the adhesion,invasion and intracellular survival ability of seven pathogens were compared,in order to screen pathogens with stronger infection ability.The effects of Salmonella and Brucella infection on the host cell related signaling pathways were investigated to provide new research ideas and targets for the clinical prevention and treatment of intracellular bacterial infection.1.Study of the infection ability of E.coli BL21,S.flexneri 2a strain 301 and Type B paratyphoid Salmonella on HeLa cells.In this study,the adhesion,invasion,and intracellular survival rates of E.coli BL21,S.flexneri 2a 301,and Type B paratyphoid Salmonella were compared,using viable bacteria counting.The results showed that the rates of adhesion,invasion and intracellular survival rates were: Type B paratyphoid Salmonella> E.coli BL21> S.flexneri 2a 301.The duration of the adhesion and invasion assay was 1 h,and the MOI were 1 and 10.The duration of the intracellular survival assay was extended to 48 h,and the MOI was 10.2.Study of the adhesion and invasion ability of seven pathogens to HeLa cells and their intracellular survival ability in four host cell lines.The adhesion and invasion rates of seven pathogens to HeLa cells and their intracellular survival rates in four host cell lines were compared by means of viable bacteria counting method in this research.The results showed that the adhesion and invasion rates of Type B paratyphoid Salmonella and Salmonella typhimurium to HeLa cells were higher than those of S.flexneri 2a strain 301,Brucella 104,Vibrio parahaemolyticus J5421,Yersinia pestis EV76,Yersinia enterocolitica.The survival rates of S.flexneri 2a strain301,Brucella 104 and Yersinia enterocolitica in RAW264.7 cells were significantly higher than those in HepG2,A549 and HeLa cells.The survival rates of Type B paratyphoid Salmonella in RAW264.7 cells were lower than those in HepG2,A549 and HeLa cells.In the early stage,the survival ability of Salmonella typhimurium and Yersinia pestis EV76 in RAW264.7 cells was higher than that of in HeLa,HepG2 and A549 cells.The survival rates of Vibrio parahaemolyticus J5421 in HeLa,HepG2,A549,and RAW264.7 cells were lower.3.The effects of Type B paratyphoid Salmonella and Brucella 104 on host cell signaling pathways were detected.The expression levels of protein associated with signaling pathway were detected by Western blot after infection of Hela cells by Type B paratyphoid Salmonella and Brucella 104.The results showed that Type B paratyphoid Salmonella could induce cell autophagy.Type B paratyphoid Salmonella could promote the expression of cilia related protein IFT88 and Giantin mAb during adhesion.The expressions of proto-oncogene related protein c-Cbl were promoted by Type B paratyphoid Salmonella infection,which also could activate the PI3K/Akt signaling pathway.Brucella 104 could induce cell autophagy.Brucella 104 could promote the expression of cilia related protein IFT88,IFT20 and Giantin mAb during invasion.The expression of cell cycle related protein CDK1 was inhibited by Brucella104 infection.The expression of proto-oncogene related protein c-Cbl was up-regulated during invasion and intracellular survival of Brucella 104.When Brucella 104 survived in HeLa cells,the PI3K/Akt signaling pathway could be activated.In summary,the study found that the adhesion,invasion and intracellular survival ability of Salmonella typhimurium and Type B paratyphoid Salmonella were very stronger.The intracellular survival ability of most pathogens were stronger in phagocyte than those in non-phagocyte,whereas Type B paratyphoid Salmonella was the opposite.Type B paratyphoid Salmonella and Brucella 104 could affect the expression of protein related to cellular signaling pathways such as autophagy,PI3K/Akt signaling pathway and proto-oncogene,which provided a theoretical basis for new prevention and treatment methods and mechanisms of intracellular pathogens.