多重基因重组型HH9N2亚型AIV福建分离株全基因组的分子特征

Molecular Characterization of Genomes of Multiplex Recombinant H9N2 Subtype AIV Isolated from Fujian

为从分子水平上了解福建省活禽市场H9N2亚型禽流感病毒的遗传演化情况及其与其他亚型禽流感病毒之间的遗传进化关系,对2015年分离自福州市某活禽市场的一株鸡源H9N2亚型禽流感病毒A/chicken/Fujian/05/2015(H9N2)进行了全基因组扩增、克隆、测序,并对所获得的全序列与参考株进行了8个基因片段的同源性比较和遗传进化分析。结果显示:该分离株的HA基因与鸡源病毒A/chicken/Zhejiang/SIC40/2015(H9N2)的核苷酸同源性最高,裂解位点处氨基酸序列为-PSRSSR↓GLF-,符合低致病性裂解位点序列特征,其226位氨基酸为L,具有与哺乳动物唾液酸α,2~6受体结合的特性;NA基因颈部63、64和65位点氨基酸有缺失,与鸡源病毒A/chicken/Zhejiang/SIC32/2014(H9N2)的核苷酸同源性最高;M2基因的31位氨基酸为N,表明该病毒已经对金刚烷胺类药物产生耐药性;分离株的基因组由3个亚系的基因重组产生,其中HA和NA基因来源于BJ/94亚系,PB2和M基因来源于G1亚系,PB1、PA、NP和NS基因来源于F98亚系;该分离株的6个内部基因PB2、PB1、PA、NP、M、NS与H7N9、H10N8、H5N6亚型禽流感病毒的内部基因存在复杂的交叉重组现象。因此需加强对H9N2亚型禽流感病毒的流行病学监测。

In order to understand the genetic evolution of H9N2 subtype avian influenza virus in live poultry marketin Fujian province and its genetic relationship with other subtype avian influenza viruses at the molecular level, genomic amplification, cloning and sequencing of the chicken H9N2 subtype avian influenza virus A/chicken/Fujian/05/2015 （H9N2） were performed and the homology and phylogenic characterization of the 8 complete sequences were analyzed with the reference strains. The results showed that the HA gene of this isolate had the highest nucleotide homology with the virus A/chicken/Zhejiang/SIC40/2015 （H9N2）. The cleavage site of HA gene was -PSRSSR GLF-, which was a low-pathogenic cleavage site sequence characteristic. The amino acid sequence at the cleavage site was -PSRSSR ,↓ GLF-, which was consistent with the sequence of the low-pathogenic cleavage site. The amino acid at position 226 was L, which had the property of binding to the mammalian sialic acid α, 2 to 6 receptor. The amino acid at 63, 64 and 65 of NA gene was deleted. The NA gene of this isolate had the highest nucleotide homology with the virus A/chicken/ Zhejiang/SIC32/2014 （H9N2）. The amino acid at position 31 of the M2 gene was N, indicating that the virus had become resistant to amantadine. The genome of the isolate was produced by recombination in three sublineages. HA and NA genes were derived from BJ/94 sublineage, and PB2 and M genes were derived from GI sublineage, while PB1, PA, NP and NS genes were derived from the F98 sublineage. The internal genes PB2, PB1, PA, NP, M and NS of the isolate had complex cross-recombination with the internal genes of H7N9, H10N8 and H5N6 subtype avian influenza viruses. Therefore, epidemiological surveillance of H9N2 subtype of avian influenza virus should be strengthened.