沙眼衣原体E型DNA疫苗细胞免疫效应研究

Cellular immune responses induced by DNA vaccine against Chlamydia trachomatis E serotype

目的研究构建的沙眼衣原体E型DNA疫苗所产生的细胞免疫效应。方法以BALB／c小鼠为实验动物，采用肌内接种免疫的方式，将小鼠分为接种空质粒的阴性对照组、DNA疫苗免疫组和接种灭活沙眼衣原体E型原体的阳性对照组。通过观察小鼠后足垫局部的迟发型超敏反应、沙眼衣原体原体刺激后脾淋巴细胞增殖试验、ELISA检测血清IFN-γ水平、实验动物经生殖道进行同型沙眼衣原体攻击后局部的衣原体培养情况以及局部组织病理学变化来研究所构建疫苗的细胞免疫效果。结果DNA疫苗组和灭活原体组小鼠的迟发型超敏反应水平高于阴性对照组。空质粒组、DNA疫苗组和灭活原体组的脾淋巴细胞刺激指数分别为1．48±0．15、2．35±0．25、3．81±0．30，后两组与空质粒组比较差异有统计学意义，且灭活原体组增殖更明显。三组的血清IFN-γ水平分别为（309．2±157．9）μg/L、（593．3±342．6）μg/L、（2891．7±1048．8）μg/L；DNA疫苗组和灭活原体组与空质粒组比较，差异有统计学意义，且灭活原体组IFN-γ水平更高。沙眼衣原体E型原体攻击后，空质粒组小鼠生殖道局部能够培养出衣原体，生殖道局部组织有破坏。另两组衣原体培养阴性，生殖道局部组织完好。结论沙眼衣原体E型DNA疫苗免疫小鼠后能够诱导产生一定的沙眼衣原体特异性细胞免疫，该疫苗对同型沙眼衣原体的生殖道攻击具有保护作用。

Objective To study cellular immune responses induced by DNA vaccine against Chlamydia trochomatis （Ct） serotype E. Methods BALB/c mice were divided into three groups to be intramuscularly immunized by blank plasmid （negative control group）, DNA vaccine against Ct serotype E （vaccine group）, and inactivated Ct elementary body （positive control group）, respectively. Two weeks after the last immunization, delayed-type hypersensitivity （DTH） response was evaluated; MTT assay was performed to detect the proliferation of spleen lymphocytes, ELISA to measure the serum level of interferon-γ in mice. Some immunized mice underwent a genital challenge with Ct elementary body followed by isolation of Ct from exfoliated epithelial cells in genital tract and pathological examination of cervical tissue from the challenged mice. Results Compared to negative control group, vaccine group and positive control group experienced a stronger DTH response. The lymphocyte stimulating index and serum level of IFN-γ were highest in the positive control group （3.81 ± 0.30, 2891.7 ± 1048.8 μg/L）, followed by vaccine group （2.35 ± 0.25, 593.3 ± 342.6 μg/L） and negative control group （1.48 ± 0.15, 309.2 ± 157.9μg/L）, and significant difference was observed between the three groups （P 〈 0.05 or 0.01 ）. After Ct challenge, Ct was isolated from exfoliated epithelial cells and cervical tissue was damaged in the negative control group, while in the other two groups, Ct was undetected and genital tract tissue was intact. Conclusions The DNA vaccine against Ct serotype E could induce Ct-specific cellular immune responses to some extent, and offer a protection against vaginal challenge with Ct.