胃癌特异性纳米疫苗的制备及其生物学活性的研究

Preparation of Gastric Cancer Specific Nanovaccine and Study of Its Immuno-competence

目的:以胃癌特异性多肽抗原MG7为靶点研制胃癌特异性纳米疫苗,并观察其对小鼠的免疫效能。方法:人工合成胃癌MG7-Ag的模拟表位多肽,用磁力超声法将其包封于纳米乳剂中,通过透析纯化,HPLC检测其包封效率。用包封有MG7抗原肽的纳米疫苗免疫健康Balb/c小鼠,以空白纳米疫苗和PBS作为对照,测定其免疫活性,通过ELISA测定血清中抗MG7抗体的效价;ELISPOT测定小鼠脾CTL活性。同时,用表达MG7-Ag的小鼠艾氏腹水瘤细胞进行肿瘤攻击2周,观察疫苗对小鼠的保护作用。结果:成功制备了胃癌MG7-Ag的纳米疫苗,并具有较好的包封率和较好的稳定性,小鼠产生MG7抗体,ELISPOT检测包封组与对照组相比分泌IFN-γ的活性淋巴细胞数量明显增高。疫苗免疫组8只小鼠中有2只未见肿瘤形成,而对照组8只小鼠则全部成瘤。结论:胃癌MG7-Ag表位纳米疫苗具有免疫原性,可以诱导小鼠产生抗肿瘤免疫。

Objective: To develop a peptide vaccine based on MG7-Ag mimotope of gastric cancer using new nano-technology and valuate its efficacy and protective effect. Methods: Encapsulate synthesized MG7 mimotope peptide into nanoemulsion using magnetic and ultrasonic technique. Dialyse method was used to sterilize, HPLC to determine encapsulation efficiency. Select CpG motif as immune adjuvant, Balb/c mice were immunized intravenously with MG7 nanovaccine , with empty nanoemulsion and phosphate buffered saline (PBS) as control. Serum titer of MG7 antibody was determined by ELISA assay. ELISPOT was performed to test the cytotoxicity of spleen cells. The protective effect of the nanovaccine was evaluated by tumor cell challenge assay. Results: MG7 nanovaccine was successfully constructed with high stability and encapsulation efficiency. It could induce both cellular and humour immune response to MG7-Ag in mice. Tumor cell challenge shown that the tumor masses formed in the mice immunized with nanovaccine markedly smaller than those formed in the mice of control groups. 2 out of 8 immunized mice were tumor free, while none in the control groups was protected. Conclusion; Nanovaccine based on the MG7-Ag mimotope is immunogenic which can induce specific immunity response against tumor in mice. And the vaccine is partially protective.