通过用重组粘附素rAdr2和源自外膜蛋白B的蛋白片段rOmpB - 4联合免疫，增强C3H/HeN小鼠对立氏立克次体感染的保护作用。
Enhanced protection against Rickettsia rickettsii infection in C3H/HeN mice by immunization with a combination of a recombinant adhesin rAdr2 and a protein fragment rOmpB-4 derived from outer membrane protein B.
作者信息
Gong Wenping, Wang Pengcheng, Xiong Xiaolu, Jiao Jun, Yang Xiaomei, Wen Bohai
机构信息
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 20 Dong-Da-Jie Street, Fengtai, Beijing 100071, China.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 20 Dong-Da-Jie Street, Fengtai, Beijing 100071, China; Department of Clinical Laboratory, The 105th Hospital of PLA, Hefei, Anhui 230031, China.
出版信息
Vaccine. 2015 Feb 18;33(8):985-92. doi: 10.1016/j.vaccine.2015.01.017. Epub 2015 Jan 15.
BACKGROUND
Two surface proteins of Rickettsia rickettsii, outer membrane protein B (OmpB) and adhesion 2 (Adr2), have been recognized as protective antigens. Herein, the immunization with both OmpB and Adr2 was performed in mice so as to explore whether their combination could induce an enhanced immunoprotection against R. rickettsii infection.
METHODS
C3H/HeN mice were immunized with recombinant protein rAdr2 or/and rOmp-4, a fragment derived from OmpB, and then mice were challenged with R. rickettsii. After which rickettsial loads in mice were measured by quantitative PCR. The specific antibodies in mouse sera were determined by ELISA and antigen-specific cytokines secretion by mouse T cells were analyzed in vitro.
RESULTS
After challenge with R. rickettsii, the mice immunized with rAdr2 or/and rOmpB-4 had significant lower rickettsial load in livers, spleens, or lungs compared to PBS mock-immunized mice. Particularly, the load in lungs of mice immunized with both rAdr2 and rOmpB-4 was significantly lower than that with either of them. High levels of specific antibodies were detected in sera from mice immunized with rAdr2 or/and rOmpB-4, but the ratios of specific IgG2a to IgG1 induced by their combination were significantly higher than that by either rAdr2 or rOmpB-4. Following stimulation with rAdr2 or/and rOmpB-4, the INF-γ secreted by CD4(+) T cells from infected mice was significantly higher than that by cognate cells from uninfected mice. And the TNF-α secreted by CD4(+) or CD8(+) T cells from infected mice was markedly greater than that by cognate cells from uninfected mice after stimulation by their combination but not either of them.
CONCLUSION
The combination of rAdr2 and rOmpB-4 conferred an enhanced protection against R. rickettsii infection in mice, which was mainly dependent on a stronger Th1-oriented immunoresponse with greater INF-γ and TNF-α secretion by antigen-specific T cells and specific IgG2a elicited by the combination.
背景
立氏立克次体的两种表面蛋白，外膜蛋白B（OmpB）和黏附素2（Adr2），已被确认为保护性抗原。在此，对小鼠进行OmpB和Adr2联合免疫，以探究它们的组合是否能诱导增强的针对立氏立克次体感染的免疫保护作用。
方法
用重组蛋白rAdr2或/和rOmp-4（OmpB的一个片段）对C3H/HeN小鼠进行免疫，然后用立氏立克次体攻击小鼠。之后通过定量PCR测量小鼠体内的立克次体载量。用ELISA测定小鼠血清中的特异性抗体，并在体外分析小鼠T细胞分泌的抗原特异性细胞因子。
结果
用立氏立克次体攻击后，与用PBS mock免疫的小鼠相比，用rAdr2或/和rOmpB-4免疫的小鼠肝脏、脾脏或肺中的立克次体载量显著更低。特别地，用rAdr2和rOmpB-4联合免疫的小鼠肺中的载量显著低于单独使用其中任何一种免疫的小鼠。在用rAdr2或/和rOmpB-4免疫的小鼠血清中检测到高水平的特异性抗体，但它们组合诱导的特异性IgG2a与IgG1的比率显著高于单独使用rAdr2或rOmpB-4诱导的比率。在用rAdr2或/和rOmpB-4刺激后，感染小鼠的CD4(+) T细胞分泌的INF-γ显著高于未感染小鼠的同源细胞分泌的INF-γ。并且，在用它们的组合刺激后，感染小鼠的CD4(+)或CD8(+) T细胞分泌的TNF-α明显大于未感染小鼠的同源细胞分泌的TNF-α，而单独使用其中任何一种刺激时则不然。
结论
rAdr2和rOmpB-4的组合赋予小鼠针对立氏立克次体感染增强的保护作用，这主要依赖于更强的以Th1为主的免疫反应，抗原特异性T细胞分泌更多的INF-γ和TNF-α，以及该组合诱导产生的特异性IgG2a。
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