目的    检测H9N2禽流感病毒血凝素（hemagglutinin, HA）和神经氨酸酶（neuraminidase, NA）DNA疫苗保护小鼠抵抗致死量同源病毒感染的能力。方法  通过小鼠肺对肺传代，建立禽流感病毒A/chicken/Jiangsu/07/2002(H9N2) 小鼠适应株。同时，构建病毒HA和NA DNA疫苗，以不同剂量电击法免疫小鼠1或2次，在初次免疫后4周或加强免疫后1周用致死量（40 LD50）鼠适应型病毒攻击小鼠。通过测定小鼠血清抗体滴度、小鼠存活率和肺部病毒滴度来评价疫苗的效果。 结果  HA 或NA DNA 10 μg免疫1次或3 μg免疫2次均可保护小鼠抵抗致死量H9N2病毒的感染。 结论  低剂量HA或NA DNA可为抗H9N2禽病毒感染提供有效的免疫保护。

Objective  To test the protective ability of avian H9N2 virus hemagglutinin (HA) and neuraminidase (NA) DNA against lethal virus challenge in mice model.  Methods  Viral lung-to-lung passages in mice were used to obtain a mouse-adapted strain for avian H9N2 isolate A/chicken /Jiangsu/07/2002. DNA vaccines expressing H9N2 HA and NA respectively were constructed to immunize mice by electroporation. Mice were immunized once or twice (at a 3-week interval) with various dosages of DNA vaccine and were then challenged with a lethal dose (40 LD50) of mouse-adapted virus. The effectiveness of the two DNAs was evaluated by serum specific antibody titers of mice, survival rates and lung virus titers.  Results  Immunization once with HA or NA DNA at a dosage of 10 μg or twice at a dosage of 3μg provided protection for mice against lethal virus challenge. Conclusion  Either H9N2 virus HA or NA DNA can be effective in defending avian influenza virus infection.