蓝鹇源H9N2亚型禽流感病毒HA和NA基因序列分析

Sequence Analysis of the Neuraminidase Gene and the Hemagglutinin Gene of H9N2 Subtype Avian Influenza Viruses from Swinhoe's Pheasant( Lophura swinhoii)

为了探查禽流感病毒H9N2在圈养蓝鹇中的流行规律及变异情况,从圈养蓝鹇(Lophura swinhoii)分离1株H9N2亚型禽流感病毒,对其HA及NA基因进行PCR扩增并进行序列分析。本分离株的HA基因序列与Genbank中广西鸡源2014年分离株A/chicken/Guangxi/CLB02/2014(H9N2)(KT023046)的核苷酸序列相似性最高,为99%;而NA基因与登录号为KM455874,2013人源分离株A/Lengshuitan/11197/2013(H9N2)的NA核苷酸序列相似性最高,为97%。HA蛋白序列分析显示:HA的226位氨基酸残基为亮氨酸(Leu),具有哺乳动物SAα2-6受体结合的特性,裂解位点处的基序PSRSSR↓GL,明显发生1个碱性氨基酸的变异。HA蛋白具有9个潜在N-糖基化位点,分别位于29、82、141、218、298、305、313、492、551位;HA受体结合位点氨基酸变异明显。NA蛋白序列分析显示:NA蛋白颈部63~65位氨基酸缺失,具有7个潜在的糖基化位点,分别位于69、86、146、200、234、264、368位;NA蛋白红细胞结合位点、抗原决定簇区域氨基酸变异活跃。HA、NA基因进化树分析显示该分离株属于欧亚分支中Y280-Like小进化分支,与疫苗株虽属于同一进化分支中,但亲缘关系较远。蓝鹇源H9N2亚型禽流感病毒(LS/GD/P29/16)HA和NA基因发生一定程度的变异,需要加强流行病学监测。

We studied genetic mutations of the genes for neuraminidase and hemagglutinin and the molecular epidemiology of H9N2 subtype Avian Influenza Virus（ AIV） in captive swinhoe＇s pheasant （ Lophura swinhoii）. H9N2 AIV strain was isolated from captive swinhoe＇s pheasant in Guangdong province. The entire NA and HA gene fragments of the strain were amplified by PCR and sequences were analyzed. The similarity of the strain HA gene was 99% compared with H9N2 AIV A/chicken/Guangxi/CLB02/2014（ H9N2 ） （KT023046）which was the most similar sequence in Genbank. The similarity of the strain NA gene was 97% compared with H9N2 AIV A/Lengshuitan/ 11197/2013（H9N2） （KM455874）which was the most similar sequence in Genbank. The sequence analysis of the strain HA protein showed that the amino residue at site 226 was leucine. It had the characteristics of the mammal SAa2 -6 receptor binding, namely one basic amino had obvious variation in the cleavage site motif PSRSSR ↓ GL. The HA protein contained 9 potential glycosylation sites at sites 29, 82, 141, 218, 298, 305, 313, 492, and 551. The amino acids at the HA receptor binding sites varied widely. The sequence analysis of the strain NA protein showed that the NA neck protein lost amino acids at site 63 -65, and contained 7 potential glycosylation sites at sites 69, 86, 146, 200, 234, 264 and 368. It showed, amino acid residues at hemadsorbing sites and antigenic determinants of NA protein varied. The HA and NA phylogeny analysis showed the isolated strain belonging to a small evolutionary branch of Y280 - Like in the Eurasian clade which was in the same branch with the AIV vaccine strain but had a distant genetic relationship with it. The HA and NA genes of the H9N2 AIV strain（LS/GD/P29/16） from swinhoe＇s pheasant showed some variation and attention should be paid to strengthen epidemiological surveillance.