口服衣原体减毒活疫苗的评估与机理探讨

Chlamydia trachomatis (C. trachomatis), the leading cause of bacterial sexually transmitted infection (STI). STIs if untreated, can lead to tubal factor hydrosalpinx, pelvic inflammatory disease (PID), and ectopic pregnancy, and all of which can cause severe consequence of infertility in women. No commercial vaccine available due to complexity of serovars and lacking of genetic manipulation system. Studies showed that immunization with plasmid-free Chlamydia could induce immune-protection to upper genital disease but fail to control reinfection. Recently, our lab unexpectedly found that GI tract immunized mice can induce successful genital tract immune-protection to chlamydia reinfection and pathology, which indicates that GI tract may serves as a novel immunization site. In this proposal, we will investigate a live attenuated vaccine, C. muridarum organism with plasmid free mutation (CMUT3G5), evaluated the immunity protection to reinfection and pathologies in the upper genital tract in mice; investigate the mechanisms of immunity protection, and also evaluate the safety of immunization of GI inoculation of live attenuated vaccine, successfully carry out this project will provide a innovative direction for future chlamydia vaccine development.

沙眼衣原体引起的生殖道感染是一种危害严重的性传播疾病。急性感染易治疗，然而大多数女性生殖道衣原体感染呈亚临床症状或隐形感染，发现已对上生殖道造成损伤，引起输卵管病变，慢性盆腔炎，异位妊娠，不孕等，危害十分严重。开发安全有效的疫苗一直是衣原体领 域的研究热点，由于人衣原体血清型众多，加上可操作的遗传学手段匮乏，目前为止仍未有成功 的商业化疫苗面世。利用动物模型，发现生殖道感染质粒缺失的衣原体弱毒苗，可诱导有效的 免疫保护病理损伤，但对再次感染则缺乏保护。我们最新发现，衣原体生殖道感染后可长期定植肠道，并成功诱导有效的跨粘膜免疫，成功保护再次感染和病理损伤，提示肠道可作为一种新型的免疫途径。本课题将以沙眼衣原体质粒缺失株plasmid free(CMUT3)作为弱毒疫苗免疫，研究肠道免疫后对衣原体再次感染和致病的免疫保护及保护机制，安全性等系统评价，为开发新型衣原体疫苗提供依据。

背景：生殖道沙眼衣原体感染危害严重，衣原体疫苗研发势在必行，本研究立足研发减毒衣原体疫苗。质粒和重要质粒蛋白pgp3是重要的毒力因子，生殖道感染pgp3质粒蛋白缺失衣原体，不会引起上生殖道病变，因此用这种减毒衣原体更利于衣原体疫苗临床应用。鼠李糖乳杆菌GG(Lactobacillus rhamnosus GG，LGG)是一种被广泛研究和应用的肠道益生菌，口服LGG不影响Cm阴道感染小鼠病原体生殖道的上行感染、清除及其向肠道的转移和定植，亦未显著影响小鼠血清特异性IgM和IgG水平；口服LGG可减少Cm感染后小鼠脾Th17细胞应答水平，能减轻小鼠Ct感染引起的输卵管纤维化和输卵管积水。.主要研究内容：1.利用质粒缺失衣原体,质粒蛋白pgp3缺失衣原体和突变型衣原体G28.51.1进行灌胃免疫，用野生型衣原体进行生殖道感染攻毒，看是否对下生殖道感染和上生殖道的疾病产生有保护作用。2.口服鼠李糖乳杆菌GG（LGG）后，可以减轻鼠衣原体导致的上生殖道致病。.重要结果：质粒缺失衣原体,质粒蛋白pgp3缺失衣原体和突变型衣原体G28.51.1进行灌胃免疫，对生殖道感染和生殖道致病有保护作用。口服鼠李糖乳杆菌GG减轻鼠衣原体感染引起的上生殖道病变。.关键数据：1.质粒缺失衣原体和质粒蛋白pgp3制备；2.质粒缺失衣原体,质粒蛋白pgp3缺失衣原体和突变型衣原体G28.51.1灌胃免疫，对生殖道感染和上生殖道致病有保护作用。3.口服鼠李糖乳杆菌GG（LGG）后，可以减轻鼠衣原体导致的上生殖道致病。.科学意义：为临床上开发pgp3缺失型减毒沙眼衣原体口服疫苗奠定基础。口服益生菌有助于减轻衣原体导致的上生殖道病变。