H9N2亚型猪源性流感病毒对C57BL/6小鼠致病性的研究

Pathogenicity of H9N2 Subtype Influenza Virus in C57BL/6 Mice

目的探讨A/swine/heBei/012/2008/(H9N2)猪源性流感病毒(H9N2-SIV)对C57BL/6近交系小鼠的致病特征,为进一步利用该品系瞬时电位受体M2基因(transient receptor potential melastatin 2,TRPM2)敲除小鼠模型研究H9N2-SIV致血管内皮细胞损伤的作用机制奠定基础。方法经鼻腔接种途径感染C57BL/6小鼠,观测临床症状、采食量及体质量变化、死亡率、组织病理学变化;测定病毒在组织内的复制滴度及半数致死量(50%lethal dose,LD50)。结果感染后2~8d,感染小鼠精神高度沉郁,采食量降低、体质量严重下降并出现严重的呼吸困难。5~8d内60%小鼠死亡;肺脏严重水肿、出血;病理组织学变化以肺严重水肿、出血、坏死和炎性细胞渗出为主;病毒分离显示包括脑在内的所有肺外器官均分离出H9N2病毒,但肺组织病毒滴度最高,第3天和第7天分别为5.2log2和8.1log2;该毒株的LD50为10-2.5/0.1mL。结论H9N2-SIV在未经预先适应的情况下能够引起C57BL/6小鼠以肺部损伤为主的致死性全身感染,证实以C57BL/6小鼠为基础构建TRPM2基因敲除模型可作为进一步研究H9N2-SIV致血管内皮细胞损伤作用机制的动物模型。

Objective To explore the pathogenicity of A/swine/heBei/012/2008/（H9 N2）swine influenza virus（H9 N2-SIV）in C57 BL/6 inbred mice,and lay foundations for researching mechanisms of H9 N2-SIV in vascular endothelial cell damage through transient receptor potential melastatin 2（TRPM2）gene knockout mouse model.Methods C57 BL/6 mice were infected by nasal inoculation,and the changes of clinical symptoms,food intake and body mass,mortality and histopathology were observed.Replicative titers and half lethal dose（LD50）of the virus in tissues were measured.Results 2~8 days after infection,the infected mice were highly depressed,the intake of food reduced,and the weight seriously decreased along with the serious respiratory difficulty.5~8 days after infection,60% mice died;the lung had severe edema and bleeding;the pathological changes mainly included pulmonary edema,hemorrhage,necrosis and inflammatory cell exudation;the virus isolation showed that H9 N2 virus was isolated from all the extrapulmonary organs including the brain,but the titer of lung tissue was the highest,which viral titer was 5.2 log2 and 8.1 log2 on 3 rd day and 7 th day after infection,respectively.LD50 of the strain was 10-2.5/0.1 mL.Conclusion H9 N2-SIV can cause fatal systemic infection in C57 BL/6 mice with lung injury without prior adaptation.It is proved that the construction of TRPM2 gene knockout model based on C57 BL/6 mice can be used as an animal model to further study the mechanism of vascular endothelial cell injury induced by H9 N2-SIV.