日本血吸虫TPI DNA疫苗基因密码子优化增强免疫保护作用的研究

目的　 研究日本血吸虫中国大陆株磷酸丙糖异构酶基因（TPI基因）密码子优化后的DNA疫苗增强免疫保护作用的效果。 方法　 60只BALB/c雌性小鼠随机均分为A（pcDNA3.1空质粒对照组）、B（pcDNA3.1-TPI组）、C （pcDNA3.1-TPI-mHSP70组）、D（pcDNA3.1-TPI.opt组）、E（pcDNA3.1-TPI.opt-mHSP70组）等5组。每鼠肌肉注射相应的纯化质粒DNA 100 μg，每隔3周免疫1次，共3次。末次免疫后4周，每鼠经腹部皮肤攻击感染日本血吸虫尾蚴（40±1）条，42 d后剖杀，计数成虫及肝脏虫卵数。首次免疫前2 d及感染前2 d经尾静脉采血，检测IgG及IgG₁、IgG_2a的水平。攻击感染前2 d取脾脏，制备单个脾细胞，用流式细胞仪检测白细胞介素2（IL-2）、IL-4、IL-5、γ干扰素（IFN-γ）及肿瘤坏死因子（TNF）的水平。 结果　 B、C、D、E组小鼠血清均检测到特异性IgG及IgG_2a与IgG₁抗体，IgG_2a/IgG₁的比值分别为1.73、2.06、2.44、3.09。D、E组的IL-2、IFN-γ、TNF含量较B、C组均有不同程度地升高。D、E组减虫率分别为36.03%、39.03%，减卵率分别为41.71%、46.85%，均显著高于B、C组（P<0.01）。 结论 TPI基因密码子优化后的DNA疫苗相对于未优化TPI DNA疫苗能诱导小鼠产生较高的免疫保护作用，且诱导宿主产生较强的，及以Th1为主的免疫应答。

Enhancing Protective Immunity Effects of TPI DNA Vaccine against Schistosoma japonicum through Codon Optimization

Objective To study the protective effect of codon optimized TPI DNA vaccine against Schistosoma japonicum infection. Methods Sixty female BALB/c mice were randomly divided into 5 groups. The mice were injected through musculus quadriceps fexoris with 100 μg pcDNA 3.1 control（Group A），pcDNA3.1-TPI（Group B），pcDNA 3.1-TPI-mHSP70（Group C），pcDNA3.1-TPI.opt（Group D），and pcDNA3.1-TPI.opt-mHSP70（Group E）respectively. All mice were immunized for three times with an interval of two weeks. The mice were challenged with（40±1） cercariae of S. japonicum per mouse by abdominal skin penetration 4 weeks after the last immunization，and sacrificed at 42 days post-challenge，the number of worms or hepatic eggs was counted. Blood was taken for the detection of IgG，IgG₁，and IgG_2a 2 days before immunization and before challenge，respectively. Spleen cells of 2 mice from each group were cultured and stimulated with ConA and rSjCTPI peptide，and the supernatant was collected for detection of IL-2，IL-4，IL-5，IFN-γ，and TNF by flow cytometry. Results ELISA showed that the mice in groups B，C，D，and E produced specific IgG and IgG₁，IgG_2a antibody isotypes，and the ratio of IgG_2a/IgG₁ was 1.73，2.06，2.44，and 3.09，respectively. The levels of IL-2，IFN-γ and TNF in groups D and E were higher than that of groups B and C. The worm reduction rate and hepatic egg reduction rate in groups D（36.03%，41.7%） and E（39.03%，46.85%）were higher than those of groups B（26.28%，28.35%） and C（28.38%，31.39%）（P＜0.01）. Conclusions The codon optimized TPI DNA vaccine induces higher level of protective effect and Th1-biased cellular immune response than those of non-optimized TPI DNA vaccine.