γ-辐射与常规方法灭活产单核细胞李斯特菌对小鼠免疫原性的比较

Immunogenicity comparision of Listeria monocytogenes inactivated by Gamma-irradiation or traditional treatments

【目的】以产单核细胞李斯特菌(Listeria monocytogenes,LM)为模式菌,比较γ-辐射及常规的热灭活、甲醛灭活制备的灭活李斯特菌对小鼠的免疫原性。【方法】以γ-辐射、热灭活和甲醛灭活法分别制备灭活的LM;腹腔注射BALB/c小鼠,ELISA检测各组灭活菌产生的抗体水平;观察野生型LM攻击后各组的保护效果,动态监测体内带菌情况;流式细胞仪分选免疫小鼠T细胞,以T细胞转移实验评价辐射灭活的LM产生的免疫应答。【结果】辐射灭活组、热灭活组和甲醛灭活组产生的抗体水平分别为:1∶1280,1∶640,1∶160;野生型细菌攻击后这3种灭活菌产生的保护率分别为:100%、35%、30%,其中免疫辐射灭活菌的小鼠能够较快清除攻击的细菌;辐射灭活李斯特菌能够激发产生T细胞保护性免疫应答。【结论】较之传统的灭活方法,利用γ-辐射制备的灭活LM免疫小鼠后能够产生较好的保护效果。

[Objective]Listeria monocytogenes （LM） is a gram-positive facultative intracellular pathogen that can cause animal and human listeriosis. In order to use killed LM in vaccination,we compared,in a mouse model,the immunogenicity of LM that were lethally inactivated by γ-irradiation,traditional heat or formalin treatment. [Methods] BALB/c mice were inoculated intraperitoneally with these killed vaccine candidates. We detected the serum antibody titers with indirect enzyme-linked immunosorbent assay （ELISA） and evaluated the protective efficacy of each vaccine candidates by the resistance to lethal dose challenge of homologous live LM and the effect of bacterial elimination in the spleen and liver of immunized mice. Adoptive transfer of Flow Cytometry sorted T splenocytes from immunized mice to nave recipients,subsequently challenged with high dose of LM,we determined the possible role of T cell. [Results] The serum antibody level of mice inoculated with γ-irradiated LM was the highest,up to 1∶1280 as determined by ELISA,while the level of mice immunized with heat-killed or formalin-killed LM was 1∶640 or 1∶160,respectively. The protective efficacy of γ-irradiated,heat-killed or formalin-killed vaccines candidates were 100%,35% or 30%. As judged by the bacterial elimination in the organs,mice inoculated with γ-irradiated LM were the most efficiently protected group. Adoptive T cell transfer assay showed that γ-irradiated LM can trigger T cell protective immune response. [Conclusion] All the results indicated the superiority of γ-irradiation over traditional heat or formalin treatment in generating LM killed vaccine candidate. γ-irradiation may be applied to numerous bacterial vaccine candidates,and could have important potential in development of killed vaccines.