福建省鸭禽流感病毒分离株(A/Duck/Fujian/FQ107/2007〔H9N2〕)全基因测序及遗传进化分析

GENOME SEQUENCING AND PHYLOGENETIC ANALYSIS OF AN AVIAN INFLUENZA VIRUS A/DUCK /FUJIAN/FQ107/2007(H9N2) ORIGIN OF FUJIAN PROVINCE

为了解一株可引起产蛋鸭产蛋异常的H9N2亚型禽流感病毒A/Duck/Fujian/FQ107/2007(H9N2)(以下简称Dk/FQ107/07)分离株的分子特性及其遗传进化地位,运用RT-PCR方法对其基因组进行扩增,克隆至pMD18-T载体后测序。结果显示,Dk/FQ107/07病毒株的血凝素(haemagglutini,HA)蛋白裂解位点的氨基酸组成为-PARSSR↓GLF-,其静脉接种指数(intravenous pathogenicity index,IVPI)为0.04,符合低致病性禽流感病毒特征;Dk/FQ107/07株HA基因与A/chicken/Shantou/5269/2005(H9N2)同源性最高,为98.9%,和我国首次哺乳动物流感病毒分离株A/Swine/HongKong/9/98(H9N2)有较近的遗传进化关系,三者均属于经典的H9N2/Y280群系;神经氨酸酶(neuraminidase,NA)基因与中国大陆首次分离株A/chicken/Beijing/1/1994(H9N2)相比,在63、64、65位点上缺失3个氨基酸(T、E、I);核蛋白(nucleoprotein,NP)基因与高致病性鸭源禽流感分离株A/Duck/Fujian/1734/05(H5N1)和A/Duck/Fujian/9713/2005(H5N1)在同一遗传进化分支上,而从聚合酶(polymerase PA,PA)基因的遗传进化分析发现其基因属于H9N2/Y439群系。由此可见,Dk/FQ107/07可能是由不同禽流感病毒基因亚群间发生自然重排的产物。

The full genome of H9N2 subtype avian influenza virus A/Duck/Fujian/FQ107/2007（Dk/FQ107/07） isolated from Fujian province was amplified by reverse transcription-polymerase chain reaction（RT-PCR） for molecular characterization and phylogenetic analysis.The PCR products were cloned into pMD18-T vectors and sequenced.The Dk/FQ107/07 strain belonged to low pathogenic avian influenza virus（LPAIV） as the cleavage site of its hemagglutinin（HA） was-PSKSSR↓GLF-and the intravenous pathogenicity index（IVPI） was 0.04.Sequence analysis showed that Dk/FQ107/07 strain shared the highest homology（98.9%） with A/chicken/Shantou/5269/2005（H9N2） and had a close relationship with the first mammal influenza virus of A/Swine/HongKong/9/98（H9N2）.These 3 influenza viruses belonged to the H9N2/Y280 sublineage.The neuraminidase（NA） gene of Dk/FQ107/07 strain had deletion mutations at aa 63,64 and 65 when compared with the first H9N2 subtype AIV strain A/Chicken/Beijing/1/94（H9N2）.The phylogenetic analysis of the nucleoprotein（NP） gene revealed that Dk/FQ107/07,A/Duck/Fujian/1734/05（H5N1） and A/Duck/Fujian/9713/2005（H5N1） were in the same evolutionary branch.On the other hand,analysis based on the polymerase PA（PA） revealed that Dk/FQ107/07 belonged to the H9N2/Y439 sublineage.The present study concluded that A/Duck/Fujian/FQ107/2007（H9N2） might have emerged through natural reassortment among avian influenza viruses of different sublineages.