流感病毒NA蛋白糖基化修饰对病毒出芽及致病性影响与分子机制

流感病毒表面糖蛋白血凝素（HA）与神经氨酸酶（NA）在受体识别与病毒出芽中发挥重要作用。糖基化修饰是糖蛋白重要的翻译后修饰，影响蛋白的折叠与功能发挥。研究证明流感病毒HA糖基化修饰在病毒感染过程中发挥重要作用，然而NA蛋白糖基化修饰的功能研究较少。本研究前期结果发现流感病毒NA蛋白N-链接糖基化修饰对病毒的出芽与复制能力发挥重要作用。NA糖基化修饰位点突变后，NA蛋白的出芽能力降低，导致突变病毒复制能力也明显降低，但造成这种现象的分子机制不清楚。本研究将通过神经氨酸酶活性、病毒出芽、小鼠致病性等试验，研究N-链接糖基化对NA蛋白功能、病毒出芽及致病性的影响。并通过免疫印迹等方法研究糖基化对NA四聚体形成及NA蛋白胞内运输的影响，并深入研究NA蛋白糖基化修饰缺失后对内质网应激激活的影响，及内质网应激情况下对病毒复制的影响，从而进一步揭示NA蛋白糖基化修饰影响病毒出芽、复制及致病性的分子机制。

The HA and NA proteins of influenza A virus play an essential role in recognition of viral receptors and release of progeny viruses as glycoproteins. Glycosylation is an important post-translational modification of membrane proteins, which affects folding and function of proteins. Glycosylation modification of HA protein of influenza virus is one of the most important mode to evade the host innate immunity, which can effectively cover the important antigenic sites of the protein. However, the function of glycosylation modification in NA protein remains unclear. Our study indicated that the glycosylation of NA protein plays an important role in replication, budding, and pathogenicity of influenza viruses. Removing glycosylation sites of NA protein attenuated the virus budding and replication, however the molecular mechanism of this phenomenon is unclear. The neuraminidase activity assay, NA budding assay, and pathogenicity study in mice will be conducted to address the effect of glycosylation modification on the function of NA protein, virus budding, and pathogenicity. Moreover, to further elucidate the molecular mechanism of the role of NA protein glycosylation sites in virus replication and pathogenicity, the effect of NA glycosylation modification on tetramer formation and intracellular transportation of NA protein will be evaluated