H5亚型禽流感病毒（AIV）是重要的人兽共患病病原，在自然选择条件下NA基因部分缺失的H5N1亚型AIV演变为优势流行株，但其成为优势流行株的理论依据未见报道。我们前期研究发现NA茎部缺失的禽流感病毒增强了其拮抗干扰素的能力，且比NS1基因缺失拮抗干扰素的作用更强，相关机制更是不清楚。本研究的主要内容包括（1）利用反向遗传技术构建出NA基因茎部不同模式缺失的H5N1亚型重组AIV；（2）测定重组病毒的生物学特性；（3）检测NA基因部分缺失对神经氨酸酶活性的影响；（4）检测NA基因部分缺失对抗干扰素作用的影响；（5）构建真核表达不同长度NA茎部的NA蛋白，检测NA基因部分缺失对神经氨酸酶活性和抗干扰素作用的影响。研究结果可有助于阐明NA基因部分缺失在生物进化过程中的作用。

H5 subtype avian influenza virus (AIV) is an important zoonotic pathogen, which becomes the dominant strain with partial deletion in neuraminidase(NA) gene under the natural selection. However the mechanism of evolution for the virus has not yet been studied and reported. Viral replication capacity in recombinant human IFN-β pretreated Vero cells revealed that both the mutant of H5N1 subtype AIV with amino acids deletion in the NA gene and/or NS gene were required for the interferon resistance of H5N1 subtype AIVs, and the reassortment of H5N1 subtype AIV with amino acids deletion in the NA gene play more important role in the interferon resistance in our previous study, and the mechanism of evolution for the virus has not yet been studied and reported. In this project, we will perform the following experiments:(1)A group of reassortment H5N1 subtype AIVs with partial deletion in NA gene were generated by reverse genetics technology. (2)The biological characteristics of the reassortment virus es were determined. (3)The neuraminidase activity of the reassortment viruses were detected.(4) The anti-interferon ability of the reassortment viruses were detected and compared. (5) Eukaryotic expression plasmids with amino acids deletion in the NA gene were constructed and transfected, the neuraminidase activity and the anti-interferon ability of NA proteins were detected. The results may help us to understand the role of partial deletion in NA gene in the process of viral evolution.