H9N2禽流感病毒M2 DNA疫苗初免-蛋白加强免疫的保护效果研究

流感病毒M2(基质蛋白2)是A型流感病毒的一个高度保守的蛋白。由于其免疫原性较弱,本研究采用M2 DNA疫苗初免-蛋白加强的策略来考察M2的免疫保护效果。制备A/Chicken/Jiangsu/07/2002(H9N2)流感病毒的M2 DNA疫苗以及经大肠杆菌表达的去除M2跨膜区的M2蛋白即sM2。以SPF级BALB/c小鼠为模型,电击法免疫M2 DNA疫苗,滴鼻法免疫sM2蛋白,免疫间隔三周,并于末次免疫后三周以致死量5LD50流感病毒H9N2攻击小鼠,通过检测小鼠存活率、体重丢失率、肺部病毒滴度及IgG抗体水平等指标来评价免疫的保护效果。实验结果表明,基于M2的疫苗采用DNA疫苗初免蛋白加强免疫二次的免疫程序能诱导较高的特异性抗体,明显减轻小鼠流感病症,提供完全的保护。

Immune Effect of DNA Prime-Protein Boost Immune Strategy Based on H9N2 Avian Influenza Virus Matrix Protein 2

Influenza matrix protein 2 （ M2 ） is highly conserved in influenza A viruses. Considering the low immunoge- nicity of M2, DNA prime-protein boost immunization strategy was explored to improve the immune effect in our study. The M2 DNA plasmid and the sM2 protein （i. e. M2 protein without transmembrane domain expressed in E. coli） from avian influenza virus A/Chicken/Jiangsu/7/2002 （H9N2） were prepared. The M2 DNA was intramuscularly injected in- to BALB/c mice by electroporation, and the sM2 protein was administered to mice by nasal dropping. The immunization interval was 3 weeks. Three weeks after the last immunization, the mice were challenged with lethal （ 5LDs0 ） homolo- gous virus. The effects of various immune strategies were evaluated by survival rate, body weight change, lung virus titer and the M2-specific IgG antibody levels in mice. The results showed that, compared with the unimmunized mice, M2 DNA prime ＋ protein boost twice could provide complete protection for mice against lethal homologous virus challenge.