spvB/spvC基因对沙门菌毒力及宿主免疫功能的影响

Effect of spvB/spvC gene on salmonella virulence and the host immune function

目的研究spv B/spv C基因对沙门菌毒力及对宿主免疫系统的影响。方法野生型沙门菌(STM.211)、敲除spv B基因的沙门菌(STM.211-Δspv B)、敲除spv C基因的沙门菌(STM.211-Δspv C)、敲除spv B及spv C基因的沙门菌(STM.211-Δspv B.spv C)和PBS组分别经腹腔注射0.2 m L105CFU的STM.211、STM.211-Δspv B、STM.211-Δspv C、STM.211-Δspv B.spv C感染BALB/c小鼠,观察小鼠精神状态、运动情况、腹泻、体质量、毛发改变等感染中毒症状,用ELISA法测定小鼠血清IL-10、IL-12、IFN-γ水平;并分离小鼠肝、脾,观察靶器官大体观及显微镜下的病理改变。结果(1)STM.211、STM.211-Δspv B和STM.211-Δspv C组的中毒症状明显较PBS组严重,STM.211-Δspv B.spv C组与PBS组间无明显差异;(2)STM.211组、STM.211-Δspv B组、STM.211-Δspv C组的IFN-γ和IL-12分泌量均显著低于STM.211-Δspv B.spv C组(P<0.05),而IL-10的分泌量明显高于STM.211-Δspv B.spv C组(P<0.05);STM.211组、STM.211-Δspv B组、STM.211-Δspv C组间差异无统计学意义(P>0.05)。结论 (1)spv B/spv C基因缺失对沙门菌毒力影响不明显,但spv B.spv C基因共同缺失,使沙门菌毒力减弱;(2)spv B/spv C基因相对抑制TH1细胞因子IFN-γ和IL-12的分泌,促进TH2细胞因子IL-10的分泌,使免疫应答向TH2方向偏移,从而有利于病原菌抵抗和逃避宿主的免疫防御,加重感染结局。

Objective To study the effect of spv B/spv C gene on Salmonella virulence and the Host immune. Methods STM.211,STM.211-Δspv B, STM.211-Δspv C, STM.211-Δspv B.spv C and PBS were infected with 0.2 m L 105 CFU corresponding strain respectively by intraperitoneal. We observed the mental status, movement, diarrhea, weight, pelage changed hair of the infected mouse. Then the level of IL-10, IL-12, IFN-γ were detected by ELISA. Finally, we observe the pathological changes of liver and spleen with the general view and the microscope. Results Infection symptoms of STM.211, STM.211-Δspv B and STM.211-Δspv C were significantly worse than PBS group, but there was no significant difference between STM.211-spv B.spv C group and PBS group. The secretion of IFN-γ and IL-12 of STM.211, STM.211-Δspv B, STM.211-Δspv C group were significantly lower than those in the STM.211-Δspv B.spv C group（P〈0.05）, but IL-10 secretion was significantly higher than STM.211-Δspv B.spv C group（P〈0.05）. There were no statistical significance among the STM.211, STM.211-ΔSpv B, STM.211-Δspv C groups（P〈0.05）. Conclusion Salmonella virulence can be affected obviously by spv B combined with spv C gene, but not by spv B or spv C.spv B/spv C gene can inhibit the TH1 cytokines（IFN-γ and IL-12） secretion but promote the TH2 cytokines（IL-10） expression,leading immune response trend to TH2 shift. It shows that spv B/spv C gene can help the bacteria evade the host immune defenses, leading to aggravation of infection.