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目的用表达弓形虫棒状体蛋白1(ROP1)的乳酸乳球菌口服免疫小鼠,观察其所诱导的体液免疫、黏膜体液免疫和保护力。方法69只BALB/c小鼠随机分成疫苗免疫组、乳球菌对照组和生理盐水组,每次分别饲喂5×109个/鼠悬浮在缓冲液中的重组乳酸乳球菌、不含重组质粒的乳酸乳球菌及等体积的生理盐水。第27、34、48天分别从鼠尾静脉采血,分离血清,酶联免疫吸附试验(ELISA)检测IgG水平;第48天杀死3只小鼠,分离小肠黏液检测SIgA水平;第48天用弓形虫灌胃感染小鼠,观察小鼠发病情况,计算小鼠死亡率,30 d后统计小鼠肝、脑组织中的虫体数量。结果疫苗免疫组小鼠IgG水平与乳球菌对照组、生理盐水组比较,差异均有统计学意义(P均<0.01)。疫苗免疫组小鼠SIgA水平与乳球菌对照组、生理盐水组比较,差异均有统计学意义(P均<0.01)。疫苗免疫组小鼠肝、脑组织中虫体数与乳球菌对照组、生理盐水组比较,差异均无统计学意义(P均>0.05)。结论表达弓形虫ROP1蛋白的乳酸乳球菌可诱导小鼠体液免疫和黏膜体液免疫,但对弓形虫感染无保护力。
OBJECTIVE To orally immunize mice with Lactococcus lactis expressing Lactobacillus rodi 1 (Toxoplasma gondii) and to observe the humoral immunity, mucosal humoral immunity and protective ability induced by Lactococcus lactis. Methods Sixty-nine BALB / c mice were randomly divided into vaccinated group, lactococcal control group and saline group. Each group was fed with 5 × 109 recombinant Lactococcus lactis suspended in buffer without recombinant plasmid Lactococcus lactis and an equal volume of normal saline. On the 27th, 34th and 48th days, blood was collected from the tail vein of mice and the serum was separated. The level of IgG was detected by enzyme-linked immunosorbent assay (ELISA). Three mice were killed on the 48th day. Toxoplasma gondii infected mice, observe the incidence of mice, calculate the mortality of mice, statistics of the number of mice in liver and brain tissue after 30 d. Results There was significant difference in IgG level between immunized mice and Lactococcus control group and normal saline group (all P <0.01). Compared with Lactococcus control group and saline group, the SIgA level in vaccine-immunized mice was significantly different (all P <0.01). There were no significant differences in the numbers of parasites in the liver and brain tissues of mice immunized with vaccine compared with the control group and the saline group (all P> 0.05). Conclusion Lactococcus lactis expressing ROP1 protein of Toxoplasma gondii can induce humoral and mucosal humoral immunity in mice, but no protection against Toxoplasma gondii infection.