Dunstan S J, Simmons C P, Strugnell R A
Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria, Australia.
Infect Immun. 1998 Feb;66(2):732-40. doi: 10.1128/IAI.66.2.732-740.1998.
We compared the abilities of different Salmonella enterica var. Typhimurium (S. typhimurium) strains harboring mutations in the genes aroA, aroAD, purA, ompR, htrA, and cya crp to present the heterologous antigen, C fragment of tetanus toxin, to the mouse immune system. Plasmid pTETtac4, encoding C fragment, was transferred into the various S. typhimurium mutants, and the levels of antigen expression were found to be equivalent. After primary oral immunization of BALB/c mice, all attenuated strains were capable of penetrating the gut epithelium and colonizing the Peyer's patches and spleens of mice. Of all strains compared, the delta purA mutant colonized and persisted in the Peyer's patches at the lowest level, whereas the delta htrA mutant colonized and persisted in the spleen at the lowest level. The level of specific antibody elicited by the different strains against either S. typhimurium lipopolysaccharide or tetanus toxoid was strain dependent and did not directly correlate to the mutants' ability to colonize the spleen. The level of immunoglobulin G1 (IgG1) and IgG2a antibody specific for tetanus toxoid was determined in mice immunized with four S. typhimurium mutants. The level of antigen-specific IgG1 and IgG2a was significantly lower in animals immunized with S. typhimurium delta purA. Antigen-specific T-cell proliferation assays indicated a degree of variability in the capacity of some strains to elicit T cells to the heterologous antigen. Cytokine profiles (gamma interferon and interleukin-5) revealed that the four S. typhimurium mutants tested induced a Th1-type immune response. Mice were challenged with a lethal dose of tetanus toxin 96 days after oral immunization. With the exception of the S. typhimurium delta purA mutant, all strains elicited a protective immune response. These data indicate that the level of total Ig specific for the carried antigen, C fragment, does not correlate with the relative invasiveness of the vector, but it is determined by the carrier mutation and the background of the S. typhimurium strain.
我们比较了不同的鼠伤寒沙门氏菌（Salmonella enterica var. Typhimurium，S. typhimurium）菌株，这些菌株在aroA、aroAD、purA、ompR、htrA和cya crp基因中发生了突变，以研究它们向小鼠免疫系统呈递异源抗原——破伤风毒素C片段的能力。将编码C片段的质粒pTETtac4转入各种鼠伤寒沙门氏菌突变体中，发现抗原表达水平相当。对BALB/c小鼠进行初次口服免疫后，所有减毒株都能够穿透肠道上皮，并在小鼠的派尔集合淋巴结和脾脏中定殖。在所有比较的菌株中，缺失purA的突变体在派尔集合淋巴结中的定殖和持续存在水平最低，而缺失htrA的突变体在脾脏中的定殖和持续存在水平最低。不同菌株针对鼠伤寒沙门氏菌脂多糖或破伤风类毒素引发的特异性抗体水平取决于菌株，且与突变体在脾脏中定殖的能力没有直接关联。在用四种鼠伤寒沙门氏菌突变体免疫的小鼠中，测定了针对破伤风类毒素的免疫球蛋白G1（IgG1）和IgG2a抗体水平。在用缺失purA的鼠伤寒沙门氏菌免疫的动物中，抗原特异性IgG1和IgG2a水平显著较低。抗原特异性T细胞增殖试验表明，一些菌株引发T细胞对异源抗原反应的能力存在一定差异。细胞因子谱（γ干扰素和白细胞介素-5）显示，所测试的四种鼠伤寒沙门氏菌突变体诱导了Th1型免疫反应。口服免疫96天后，用致死剂量的破伤风毒素攻击小鼠。除缺失purA的鼠伤寒沙门氏菌突变体外，所有菌株都引发了保护性免疫反应。这些数据表明，针对携带抗原C片段的总Ig水平与载体的相对侵袭性无关，而是由载体突变和鼠伤寒沙门氏菌菌株的背景决定的。
