番鸭源H6N6亚型禽流感病毒全基因组的分子特征

Characterizations of avian influenza virus H6N6 subtype isolated from domestic Muscovy duck

【目的】为了丰富水禽源禽流感病毒的分子流行病学资料,明确我国国内首次分离的番鸭源H6N6亚型禽流感（Avian influenza virus,AIV）病毒A/Muscovy Duck/Fujian/FZ01/2008（H6N6）（以下简称MD/FJ/F1/08）全基因组的分子特征,弄清该病毒的遗传进化特点。【方法】对其8个基因片段分别进行扩增和序列测定,并利用分子生物学软件对测序结果进行序列分析。【结果】MD/FJ/F1/08的HA裂解位点附近的氨基酸序列为PSMKVIV↓GL,为非连续的碱性氨基酸,其静脉接种指数（the intravenoys pathogenicity index,IVPI）为0.15,推测其为一株低致病力AIV。其HA基因、NP基因、M基因和PB2基因均与我国台湾分离株A/duck/Kingmen/E322/04（H6N2）该基因的核苷酸同源性最高,分别高达94.2%、95.7%、97.2%和95.6%,均处于同一遗传进化分支。其NA基因和我国远东分离株A/duck/Eastern China/01/2007（H4N6）同源性最高,达97.1%;其颈部有11个氨基酸的缺失（TNSTTTIINNN）,为N6亚型神经氨酸酶基因中首次报道,在遗传进化上和H4N6亚型AIV的NA基因处于相同的分支。NS基因和香港地区分离株A/duck/HongKong/3600/99（H6N2）同源性最高,达96.1%;PB1和PA均与高致病性禽流感病毒株A/duck/HongKong/140/1998（H5N1）同源性最高,达95.6%和96.7%。且MD/FJ/F1/08的8基因与H6N6亚型流感病毒北美洲分离代表株均不处在同一遗传进化分支上,相互之间遗传关系较远。【结论】MD/FJ/F1/08可能是由H6N2、H4N6和H5N1等多亚型AIV基因重组而成。

[Objective]To enrich the epidemiologic data of the waterfowl origin avian influenza virus（AIV）.[Methods] The full genome of A/Muscovy Duck/Fujian/FZ01/2008（H6N6）,which was first isolated from domestic Muscovy duck in Fujian Province in southern China at 2008,was cloned and sequenced by reverse transcription polymerase chain reaction（RT-PCR）.[Results]The motif of hemagglutinin（HA） cleavage site was PSMKVIV↓GL,which is a molecular characteristic of low pathogenic AIV,and the intravenoys pathogenicity index（IVPI） was 0.15.The HA gene,NP gene,M gene and PB2 gene nucleotide sequences had similarity highest with A/duck/Kingmen/E322/04（H6N2） at 94.2%,95.7%,97.2% and 95.6%,shared the same phylogenetic lineage.The neuraminidase（NA） gene had similarity highest with A/duck/Eastern China/01/2007（H4N6） at 97.1 per cent,and also had 11 continuous amino acids（TNSTTTIINNN） deletion in the NA gene stalk region,which was first reported had deletion 11 amino acids in N6 subtype AIV NA genes＇ORF.The NA gene had familiar phylogenetic relationship with H4N6 subtype AIV.The NS gene、PB1 gene and the PA gene had genetically close relationships with the H5N1 high pathogenic AIV strains isolated in Hong Kong at 1997.The eight genes also showed any immediate ancestor with other H6N6 subtype avian influenza viruses isolated in North America.[Conclusion]These data showed that A/Muscovy Duck/Fujian/FZ01/2008（H6N6） was possibly a reassortant virus derived from H6N2 subtype、H4N6 subtype and H5N1 subtype AIV.