H9N2亚型禽流感病毒血凝素蛋白分子特征分析及其对小鼠致病力的研究

Analysis of Hemagglutinin Molecular Characterization of H9N2 Avian Influenza Virus and Study on Its Pathogenicity to Mice

旨在了解H9N2禽流感病毒(AIV)山东分离株血凝素(HA)的遗传变异情况及其对哺乳动物的致病性。对5株H9N2AIV山东分离株的HA蛋白的分子特征进行了分析,并以BABL/c小鼠为模型评价其致病性。结果表明:5株AIV均属于CK/Beijing谱系,其中2株病毒的HA具有人样受体结合特征(Leu234),3株病毒具有禽样受体结合特征(Gln234)。裂解位点分析表明,5株病毒均具有低致病性AIV特征;个别病毒的潜在糖基化位点存在增加或缺失现象。攻毒BABL/c小鼠后,2株病毒能够在小鼠肺部复制,病理切片显示间质性肺炎病变,通过免疫组化染色在细支气管上皮细胞检测到病毒。研究表明,H9N2亚型AIV在进化过程中HA基因及其编码的蛋白存在一定的差异性,且5株山东分离株中有2株具备感染哺乳动物的能力。该试验结果为从分子水平上深入研究H9N2亚型AIV HA蛋白氨基酸位点与跨种传播的关系提供了理论依据。

The study was conducted to understand the evolution of hemagglutinin of H9N2subtype avian influenza viruses(AIV)isolated from Shandong province and evaluate their pathogenicity to mammals.We analyzed hemagglutinin amino acids sequences of 5 H9N2AIV isolated from Shandong province,and assessed their pathogenicity to mammals by using BABL/c mice model.The results indicated that all 5strains belonged to CK/Beijing lineage.Two strains of them possessed human-like receptor binding specificity(Leu234),while other three possessed avian-like receptor binding specificity(Gln234).The HA cleavage site showed that all the strains were low pathogenic.Potential glycosylation sites varied among the viruses.Two strains could replicate in mice's lung,caused interstitial pneumonia,and could be detected in bronchial epithelial cells by immunohistochemistry.Our study demonstrated that the HA gene and its coding protein had some difference during the evolution of H9N2subtype AIV,and two of the researched strains could infect mammal.This study provided theoretical basis at molecular level for further studies on amino acids of H9N2subtype AIV HA protein,which relate to cross-species transmission.