双歧杆菌介导的福氏志贺菌Bb-ipaB疫苗免疫机制研究

Study on the immune mechanism of a recombinant Bb-ipaB vaccine against Shigella flexneri

目的探讨双歧杆菌(Bifidobacterium bifidum,Bb)介导的福氏志贺菌(Shigella flexneri)Bb-ipaB疫苗的免疫机制。方法雌性BALB/c小鼠随机均分为3组:疫苗组(Bb-ipaB)、Bb组和PBS组。每周灌胃免疫1次,共4次。未次免疫1周后检测小鼠血清特异性IgG、IgE、IgA及小肠黏液sIgA;取小鼠胸腺和脾脏,称重,计算胸腺和脾指数;采用MTT法检测脾细胞增殖活性,采用ELISA法检测脾细胞因子IFN-γ和IL-4水平。结果疫苗组小鼠血清特异性IgG、IgE、IgA,小肠黏液sIgA,胸腺脾指数,脾细胞增殖能力及脾细胞IFN-γ和IL-4水平均显著高于对照组(P<0.01)。结论 Bb-ipaB疫苗免疫可刺激小鼠产生高水平的特异性抗体和细胞因子,并能促进脾细胞增殖,具有开发潜能和研究价值。

Objective To explore the immunity provided to BALB/c mice by immunization with a Bifidobacterium bifi- dum mediated Bb-ipaB vaccine against Shigella flexneri. Methods Female BALB/c mice were randomly divided into 3 groups： a vaccine group, Bb control group, and PBS control group. Mice were orally immunized once a week a total o{ four times. Changes in antibodies （IgG, IgE, and IgA） in serum, sIgA in the mucosa, and cytokines of splenocytes （IFN-γ, IL-4） were detected in mice using ELISA and the capacity for splenic cell proliferation was detected using MTT. Results The S. flexneri vaccine group had a higher level of antigen-specific antibodies （IgG, IgE, and IgA） and cyto- kines （IFN γand IL-4） of splenocytes, greater capacity for splenic cell proliferation, and higher thymus and spleen index than these of controls. Conclusion The S. flexneri vaccine Bb-ipaB can produce higher levels of antigen-specific anti- bodies （IgG, IgE, IFN-γ, IL-4, and IgA） and cytokines （IFN-γ and IL-4） of splenocytes after oral immunization. This vaccine may be a potentially valuable oral vaccine to prevent infection with S. flexneri.