沙门菌外膜蛋白相关基因缺失株的致病性

Pathogenicity of Salmonella strains with gene deletion related to outer membrane protein

为探究沙门菌外膜蛋白基因fadL、ompN、ybfM以及sRNA RybB和伴侣蛋白Hfq缺失对该菌致病性的影响,构建了鼠伤寒沙门菌基因缺失菌株,并测定了基因缺失菌株的生长曲线,同时通过小鼠腹腔注射测定了基因缺失菌株的毒力及其在小鼠脾脏和肝脏上的定殖能力.结果显示,与鼠伤寒沙门菌亲本野生型菌株LT2相比,基因缺失菌株的生长能力变化不大.LT2对小鼠的LD_(50)为3.97×10^(7)CFU;外膜蛋白基因缺失菌株ΔompN、ΔfadL和ΔybfM的LD_(50)分别为1.58×10^(5)、6.29×10^(5)、9.97×10^(5)CFU,毒性明显增强;sRNA敲除菌株(ΔrybB)的LD_(50)为9.97×10^(7)CFU,毒性有所下降;伴侣蛋白Hfq敲除组(Δhfq)及rybB&hfq双敲除组的小鼠死亡数未超过50%,毒性明显下降.感染48 h后,与对照组(LT2)相比,所有基因缺失菌株处理组的脾脏指数均极显著性升高;ΔrybB&Δhfq、Δhfq处理组的脾脏载菌量显著降低,其余菌株处理组的载菌量与LT2差异不显著;ΔrybB、ΔrybB&Δhfq、ΔfadL、ΔybfM处理组的肝脏指数均显著下降,而Δhfq、ΔompN处理组的肝脏指数变化不显著;ΔrybB、ΔfadL处理组肝脏载菌量变化不显著,Δhfq、ΔrybB&Δhfq处理组的肝脏载菌量显著下降,而ΔompN、ΔybfM处理组的载菌量显著上升.总的来说,hfq、rybB缺失降低了鼠伤寒沙门菌的致病力,而fadL、ompN、ybfM的缺失提高了鼠伤寒沙门菌的致病力.

To explore the influence of the loss of Salmonella outer membrane protein genes(fadL,ompN,ybfM)and sRNA RybB and chaperonin Hfq on the pathogenicity of the bacteria,S.typhimurium deletion mutants were constructed,and the growth curves of the deleted strains were measured.The virulence of the deleted strains and the colonization abilities on the spleen and liver of mice were determined after intraperitoneal injection.The results showed that the growth of the deletion strains barely changed compared with the wild-type parent strain LT2.The LD_(50)of LT2 to mice was 3.97×10^(7)CFU while it declined to 1.58×10^(5),6.29×10^(5),and 9.97×10^(5)CFU forΔompN,ΔfadL andΔybfM,respectively,indicating significantly enhanced toxicities;theΔrybB group experi-enced reduced toxicity,with increased LD_(50)reaching 9.97×10^(7)CFU;Δhfq and the double knockout of rybB and hfq also resulted in significantly reduced toxicity,with death rates under 50%.After getting infected for 48 h,the spleen indexes of all mice injected with deleted strains increased significantly;bacterial loadings of mice injected with double knockout mutant andΔhfq reduced signif-icantly,while those injected with other strains were not significantly different from the control;liver indexes were decreased inΔrybB,ΔrybB&Δhfq,ΔfadL,andΔybfM treatments while almost remained the same inΔhfq andΔompN treatments;bacteria loadings were significantly declined in mice liver treated withΔhfq and double knockout mutant while elevated in groups injected withΔompN andΔybfM;it almost remained the same inΔrybB andΔfadL treatments.To summarize,the deletions of hfq and rybB reduce the virulence of S.typhimurium while the deletions of fadL,ompN,and ybfM increase the virulence.