沙眼衣原体Ⅲ型分泌系统效应蛋白CT143保护小鼠抵抗衣原体生殖道感染

Chlamydia trachomatis type Ⅲ secretion system effector protein CT143 protects mice against chlamydial urogenital tract infection

目的:探讨沙眼衣原体(Ct)Ⅲ型分泌系统效应蛋白CT143免疫小鼠后,对小鼠抵抗衣原体生殖道感染的保护作用。方法:分别用重组CT143蛋白、CT143+CpG或CPG佐剂滴鼻免疫BALB/c小鼠3次,末次免疫30 d后,用鼠衣原体(Cm)进行阴道感染攻击;ELISA法检测血清CT143特异性IgG抗体水平及亚类;CT143蛋白体外刺激脾细胞,ELISA试剂盒检测脾细胞因子IFN-γ和IL-5产生情况;阴道接种感染衣原体后,每隔4 d,间接免疫荧光法监测小鼠阴道脱落上皮中的衣原体含量;阴道感染60 d后,分离小鼠完整生殖道,肉眼评估生殖道病变,并用HE染色观察输卵管的组织结构改变及炎症细胞浸润情况。结果:CT143+CpG滴鼻免疫可诱导小鼠产生高滴度的特异性IgG抗体,抗体亚类以IgG2a为主;CT143+CpG免疫组小鼠脾细胞Th1型细胞因子IFN-γ较CT143免疫组显著升高,Th2型细胞因子IL-5较CT143免疫组显著降低;CT143+CpG免疫组小鼠下生殖道排菌量较对照组减少、排菌时间缩短,输卵管积水程度轻,积水主要发生于单侧,镜下结构清晰,炎症细胞浸润少。结论:CtⅢ型分泌系统效应蛋白CT143与佐剂CpG滴鼻免疫可保护小鼠抵抗衣原体的生殖道感染,其保护机制与诱导的Th1型细胞免疫应答有关。

Objective:To investigate the protection effects of Chlamydia trachomatis(Ct)type Ⅲ secretion system effector protein CT143 against genital Chlamydial infection in mice.Methods:BALB/c mice were immunized intranasally for 3 times with recombinant CT143,CT143 plus CpG adjuvant,or CpG alone. 30 d after last immunization,mice were challenged intravaginally with Chlamydia muridarum(Cm). Serum anti-CT143 specific IgG level and its subclasses were analyzed by ELISA. Splenocytes were collected for in vitro re-stimulation with CT143 and the culture supernatants were assayed to determine the levels of IFN-γ and IL-5 using ELISA kits. To monitor live organism shedding,vaginal swabs were collected every 4 d after intravaginal infection,and the total number of IFUs per swab were detected using indirect immunofluorescence assay. 60 d after infection,the intact reproductive tracts were isolated and the lesions were first evaluated by naked eyes,then HE staining was used to observe changes of tissue structure and inflammatory cell infiltration of fallopian tubes.Results:CT143+CpG intranasally immunized mice exhibited significantly enhanced titers of antiCT143 total antibody and IgG2 a antibody. Compared with CT143 immunized group,Th1 cytokine IFN-γ production in CT143+CpG immunized group was significantly increased while Th2 cytokine IL-5 was significantly decreased. Compared with control group,CT143+CpG immunized mice had less feculent amount and shorter feculent time in lower reproductive tract,and the degree of hydrosalpinx was mild. Hydrosalpinx mainly occurred on one side,with clear structure and less inflammatory cell infiltration under microscope.Conclusion:Ct type Ⅲ secretion system effector protein CT143 plus adjuvant CpG intranasal immunization can protect mice against chlamydia genital tract infection,the protection mechanism is related to Th1 dominant cellular immune response.