Objective To observe immune responses and heterosubtypic protection elicited by an inactivated influenza H5N1 vaccine with different immunization routes in mice. Methods BALB/c mice were intraperitoneally injected or intranasally immunized with the inactivated H5N1 vaccine, the mice administered with PBS were used as control. Weight loss and survival in mice were observed after PR8 or a H9N2 virus challenge. Serum specific IgG antibody and its subclasses were detected by ELISA kits. Ratios of CD4+ /CD8+ lymphocytes in spleens of mice were assayed. The t-test was used in the comparison of different groups.Results After challenge, weight loss was found in all groups, but the weight of mice in vaccination groups returned to normal later. The mice in PBS groups all died. The vaccinated mice were completely protected against PR8 and partly protected against H9N2 virus. The level of IgG antibody increased significantly after vaccination, and the increase magnitude of IgG2a was higher than that of IgG1. The ratios of CD4+ /CD8+ lymphocytes in spleens of vaccinated mice decreased after challenge (t=6. 8017,P<0. 01) , especially in the intranasal group (t = 3. 9701, P < 0. 05 ). Conclusions Both intraperitoneal injection and intranasal immunization can induce a high level of specific IgG, especially the level of IgG2a, and provide protection against heterosubtypic viruses. Intranasal immunization seems to induce a higher level of CD8+ T cell response.%目的 观察禽流感H5N1灭活疫苗以不同方式免疫后诱导的免疫应答及抗异亚型病毒攻击的保护作用.方法 将H5N1灭活疫苗分别通过腹腔和滴鼻方式免疫BALB/c小鼠,同时以PBS作为对照;免疫后分别以PR8和H9N2病毒攻击,观察小鼠的体重变化和生存情况.采用ELISA对各组小鼠攻毒后不同时间的血清IgG及其亚类水平进行动态检测;流式细胞仪检测脾淋巴细胞亚群情况.采用t检验对各组数据进行比较.结果 PR8和H9N2病毒攻击后,各组小鼠体重均下降,但疫苗组小鼠于后期体重恢复正常,存活率分别为100%和70%-80%,而PBS组小鼠则全部死亡.无论以何种方式免疫,疫苗组的特异性IgG及其亚类水平均明显升高,其中以IgG2a水平升高更为明显.攻毒后疫苗组小鼠脾CD4+与CD8+T淋巴细胞比值出现下降(t=6.8017,P<0.01);滴鼻免疫组与腹腔免疫组相比降低更明显(t=3.9701,P<0.05).结论 H5N1疫苗免疫原性良好,可诱导较高水平的特异性抗体产生,诱导的抗体亚类以IgG2a为主.两种免疫方式均可对小鼠提供很好的异亚型保护,而滴鼻免疫能够诱导更强的CD8+T细胞应答.
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