1株含H9N2内部基因的H5N1亚型基因重配禽流感病毒的全基因测序及遗传进化分析

Genome Sequencing and Genetic Analysis of a Natural Reassortant H5N1 Subtype Avian Influenza Virus Possessing H9N2 Internal Genes

在对华东地区家养水禽中流感病毒的带毒状况的流行病学监测过程中,从表观健康家鸭体内分离到一株H5N1亚型禽流感病毒A/duck/Shandong/009/2008(简称Dk/SD/009/08)。为了解该毒株的基因组构成,对该分离株进行全基因测序。测序结果显示:该毒株HA裂解位点处的氨基酸序列为PLRERRRK-R/GL,符合高致病性禽流感病毒的分子特征,且参照H5N1国际统一命名准则,Dk/SD/009/08的HA基因属于2.3.4进化支。BLAST结果显示,HA、NA、NP及NS基因均与H5N1亚型病毒的核苷酸一致性最高,而RNA聚合酶基因(PB2、PB1、PA)及M基因则与H9N2亚型病毒的亲缘关系最近,故推测该分离株可能是一株天然重组病毒;遗传进化分析进一步表明,流行于华南地区鹌鹑中的G1-like H9N2亚型病毒可能为该分离株提供部分的内部基因。

One H5N1 subtype avian influenza virus,A/duck/Shandong/009/2008（Dk/SD/009/08）,was isolated from apparently healthy domestic ducks in some live bird market in East China during our epidemiological surveillance.To investigate the genetic composition,Dk/SD/009/08 was subjected to genome sequencing.The amino acid motif of cleavage site was ＂PLRERRRK-R/GL＂,which was consistent with the characterization of the HPAIV.According to the newest unified nomenclature system of H5N1,Dk/SD/009/08 was classified into Clade 2.3.4.The BLAST results showed that four gene segments（HA,NA,NP and NS）had the highest nucleotide identities with H5N1 subtype AIVs whereas the remaining four（PB2,PB1,PA and M）displayed the closest relationship with H9N2 subtype.Therefore,Dk/SD/009/08 might be a natural reassortant virus.The phylogenetic analysis further indicated that G1-like H9N2 subtype AIVs which was prevalent mainly in quails of Southern China might provide the internal genes for Dk/SD/009/08.