胸腺素及干扰素基因表达对乙型肝炎基因疫苗的免疫增强效应

目的观察胸腺素及干扰素基因表达对乙型肝炎基因疫苗pVAX1-S2S的免疫增强效应。方法从乙型肝炎患者血清中扩增S2S基因，构建表达质粒PVAX1—S2S。从成人外周血白细胞总RNA中，逆转录聚合酶链反应扩增干扰素α基因Ⅰ，将其与S2S相连接，构建重组表达质粒PVAX1—I／S2S；将干扰素α基因Ⅰ与人工合成的胸腺素α基因T相连接，构建重组表达质粒pVAX—T／I。将上述表达质粒分组肌肉接种BALB／c小鼠：单独免疫组接种pVAX1-S2S 100μg；联合免疫组1：接种pVAX1—I／S2S 100μg；联合免疫组2：每只小鼠同时接种pVAX1—T／I与pVAX1-S2S各50μg。上述各组于2、4周后分别加强免疫1次。然后动态检测小鼠血清抗-HBS和前S2抗体。结果接种后3、5、8周，小鼠血清抗-HBS阳转率：联合免疫组1分别为12．5％、12．5％、62．5％；联合免疫组2分别为25％、50％、50％，二者总体上均优于pVAX1—S2S单独免疫组。联合免疫组2的前S2抗体水平则高于其它两组。结论胸腺素α1和(或)干扰素α8基因的表达具有分子免疫佐剂的效应，能够增强乙型肝炎基因疫苗的特异性体液免疫诱生效力。

Immune response enhanced by genes encoding IFN-alpha 8 and T alpha 1 co-inoculated with HBV DNA vaccine

OBJECTIVES: To evaluate if the humoral immune response of hepatitis B DNA vaccine pVAX1-S2S could be enhanced by Talpha1 and/or IFNa expression plasmid co-inoculated. METHODS: The following mammalian expression recombinant plasmids were constructed: the plasmid pVAX1-S2S expressing hepatitis B surface antigen S2S, the plasmid pVAX1-T/I co-expressing thymosin a and IFNalpha, the plasmid pVAX1-I/S2S co-expressing IFNalpha and S2S. These plasmids were inoculated intramuscularly into several BALB/c mice groups in different combinations. In the co-immunization group 1 (pVAX1-I/S2S), each mouse was inoculated with 100 microg of pVAX1-I/S2S; in the co-immunization group 2 (pVAX1-S2S) each mouse was co-inoculated with pVAX1-S2S and 50 microg of pVAX1-TI; in the control group each mouse was inoculated with 100 microg of pVAX1-S2S. All the immunizations were boosted at 2 and 4 week intervals; then the serum samples were collected to detect the anti-HBs and anti-preS2 strengths. RESULTS: 3, 5 and 8 weeks after the first inoculation, the positive rates of anti-HBs were 12.5%, 12.5%, 62.5% respectively in the co-immunization group 1 and 25%, 50%, 50% in the co-immunization group 2, while those in the control group were 0, 25%, 37.5%. The titers of anti-preS2 in co-immunization group 2 was 5 times higher than those in the other two groups. CONCLUSION: The data shows that Talpha1 and/or IFNalpha expression plasmid co-inoculated with pVAX1-S2S might act as an adjuvant to enhance the humoral immune response induced by pVAX1-S2S.