中文摘要：

为研究两株H7亚型流感病毒A／chicken／Jilin／SD020／2014（H7N2）（简称JL／020）和A／Anhui／1／2013（H7N9）（简称AH／1）受体结合特异性差异的影响机制，本实验利用反向遗传操作技术，构建一系列重配病毒和HA基因点突变病毒，检测其对受体结合特性的影响。固相ELISA检测结果表明血凝素蛋白（HA）中的57和312位氨基酸不影响流感病毒的受体结合特性，而神经氨酸酶蛋白（NA）使r-JL／020fAH／1骨架1结合SAa2，3Gal受体的结合能力高于r-AH／1（R57K／R312K），表明NA影响了流感病毒受体结合特性；同源建模进一步发现HA中的57和312位点与流感病毒受体结合结构域相距较远；交叉血凝抑制试验（HI）结果表明，H7单因子血清和H7N9全病毒血清对拯救的JL／020和AH／1病毒株的抑制价没有差异，而N2单因子血清对病毒的抑制能力存在差异。以上结果表明，NA蛋白影响了流感病毒的受体结合特性。本研究表明，除HA以外，NA也能够影响流感病毒的受体结合特性，该实验为进一步研究流感病毒受体结合特性提供了实验依据。

英文摘要：

Two H7 subtype influenza viruses, A/chicken/Jilin/SD020/2014 （H7N2） （JL/020） and A/Anhui/1/2013 （H7N9） （AWl）, were selected to study the mechanism of receptor-binding specificity in this study. To investigate which factor influences the receptor-binding property, a series of reassortants and mutant viruses were constructed by using 8 plasmid-based reverse genetics. Solid-phase ELISA assay showed that the receptor-binding specificity of AH/1 was not affected by the R57K and RInK mutations in HA, while N2 NA increased the binding affinity against SAet2,3Gal of r-JL/020（AH/1 backbone）, indicating that NA influenced the receptor-binding property. Homologous modeling further showed that the aa57 and aa312 in HA were not located in the receptor-binding domains. The hemagglutination inhibition （HI） antibody titers of the H7 HA single factor and H7N9 whole virus sera against JL/020 and AH/1 virus were both 4 and 7, respectively, while the HI titers of the N2 NA sera against the two viruses were different. All these results indicated that NA protein influenced the receptor-binding properties. This study demonstrates that, in addition to HA, NA has also an important role on receptor-binding specificity of influenza A virus, which provides a basis for further study of receptor-binding properties.