【作者】 孙静；

【导师】 刘振生； 柴洪亮；

【作者基本信息】 东北林业大学 ， 野生动植物保护与利用， 2020， 博士

【摘要】 禽流感(Avian Influenza,AI),是由禽流感病毒(Avian Influenza Virus,AIV)引起的家禽和野禽的一种传染病,表现为从呼吸系统到全身败血症等多种综合征。AIV已在全球范围内多种禽类物种中传播,给家禽养殖业造成了巨大的经济损失,同时,能够感染人类的AIV亚型越来越多,主要以H5和H7为主。候鸟被认为是AIV的天然贮存库和遗传多样性的基因库,候鸟感染后通常不发病,通过迁徙的方式将AIV传播扩散至其他地区,在传播过程中,经过持续不断的基因突变或重组,可能产生新的高致病性毒株,因此候鸟对AIV的持续存在、进化和不断传播具有重要作用。通过对候鸟AIV的主动监测研究,了解掌握候鸟携带AIV的情况、AIV的遗传变异规律,继而阐明候鸟与AIV的时空分布关系,可对禽流感疫情的跨境扩散进行预警指示,为禽流感预警、防控提供科学的依据,意义重大。本研究于2015年5月至2019年8月,在青藏高原斑头雁的繁殖期和越冬期持续对斑头雁等候鸟样品进行采集,进而1、对青藏高原斑头雁等候鸟AIV感染状况进行监测,2、对代表性分离株进行全基因克隆和全基因组序列的遗传进化分析,3、进行斑头雁与青藏高原AIV的时空分布相关性分析。一、青藏高原斑头雁等候鸟AIV的监测研究及代表性分离株的遗传进化分析2015年5月至2019年8月,我们在青藏高原共采集野鸟样品28692份,分离到87株AIV,平均病毒分离率为0.3%。亚型鉴定结果显示,分离到多种亚型的AIV,其中HA优势亚型为H5(90.8%),NA优势亚型为N1(45.9%)和N8(50.6%)。遗传进化分析结果显示,同一种亚型AIV存在不同的基因型,青藏高原候鸟中流行的AIV间存在广泛的基因重组,部分基因在北美大陆和欧亚大陆之间、在欧亚大陆和非洲大陆之间存在基因交流,青藏高原H5N1和H5N8亚型AIV与斑头雁迁徙路线上其他栖息地AIV高度同源。二、斑头雁与青藏高原AIV的时空分布相关性分析在遗传进化分析的基础上,我们进一步进行谱系地理发生学分析。结果显示,2015年青藏高原候鸟H5N1亚型高致病性禽流感疫情可能来源于印度家禽源H5N1亚型HPAIV:2016年青藏高原候鸟H5N8亚型高致病性禽流感疫情可能经斑头雁等候鸟迁徙由西藏传播扩散至俄罗斯,再由俄罗斯可能扩散至印度等南亚国家。由于中国周边国家缺少流感早期监测数据,因此青藏高原病毒来源尚不清楚;H5N1和H5N8禽流感疫情扩散或病毒传播的时空节点与斑头雁等已知的候鸟迁徙时空节律均一致,揭示斑头雁可能携带H5N1和H5N8亚型HPAIV进行长距离的迁徙,在迁徙过程中可与其他候鸟相互传播病毒,并发生基因重组;病毒的传播不仅发生于候鸟的某一迁徙通道上,而且不同迁徙通道的重叠、不同候鸟的混群交汇加速了 AIV的传播和扩散。更多还原

【Abstract】 Avian influenza is an infectious disease of poultry and wild birds,caused by avian influenza virus(AIV),manifested in a variety of syndromes from respiratory system to systemic sepsis.AIV has spread in a variety of poultry species worldwide,causing huge economic losses to the poultry industry.At the same time,more and more subtypes of AIV have acquired the ability to infect people,mainly H5 and H7.Migratory birds were considered to be the natural reservoir of AIV and the gene pool of genetic diversity.Migratory birds usually do not develop disease after infection,and spread AIV to other areas through migration.During the transmission process,new highly pathogenic virus may be generated through genetic mutation or reassortment,so migratory birds play an important role in the continuous existence,evolution and transmission of AIV.Through active surveillance and research on AIV in migratory birds,then to understand the situation of migratory birds carrying AIV and the genetic variation rule of AIV,and then to clarify the temporal and spatial distribution relationship between the migratory birds and AIVs.It could provide an early warning indicator for the cross-border spread of AIV and a scientific evidence for early warning,prevention and control of avian influenza.In this study,we collected samples of bar-headed geese and other wild birds in the breeding season and overwintering season of the bar-headed goose on the Qinghai-Tibet plateau from May 2015 to August 2019,and the following studies were conducted.A.Surveillance of AIV in bar-headed goose on Qinghai-Tibet plateau and the phylogenetic analysis of representative isolatesFrom May 2015 to August 2019,a total of 28,692 samples were collected from wild bird on the Qinghai-Tibet plateau,and 87 AIV strains were isolated,with an average virus isolation rate of 0.3%.The results of subtupe identification suggested diverse subtypes of AIV were isolated,and the dominant subtype of HA is H5 subtype(90.8%),for NA being N1(45.9%)and N8 subtype(50.6%).Phylogenetic analysis showed that there were different genotypes of the same subtype of AIV and multiple reassortments occurred in AIVs circulating in migratory birds on the Qinghai-Tibet plateau.Some genes could flow between North America and Eurasia,and between Eurasia and Africa.H5N1 and H5N8 AIV circulated on Qinghai-Tibet plateau shared high nucleotide homology with other AIVs circulated in other habitats along the migration route of bar-headed goose.B.Correlation analysis of temporal and spatial distribution of bar-headed goose and AIV on Qinghai-Tibet plateauOn the phylogenetic analysis,we have gone ahead the phylogeographic analysis.The results showed that the outbreak of H5N1 HPAIV in wild bird,occurred on Qinghai-Tibet plateau in 2015,may be caused by poultry-derived H5N1 HPAIV in India.The outbreak of H5N8 HPAIV in wild birds on Qinghai-Tibet plateau in 2016 maybe spread to Russia through the migration of bar-headed goose;subsequently spread to South Aisa countries such as India from Russia.The source of the H5N8 HPAIV on the Qinghai-Tibet Plateau remains unclear because of the lack of early surveillance data for influenza virus in neighboring countries.The temporal and spatial nodes of H5N1 and H5N8 outbreaks and spread of virus was consistent with the known migratory routes of migratory birds,such as bar-headed goose.Bar-headed geese maybe carry H5N1 and H5N8 HPAIV for long-distance migration,and during the migration,other migratory birds could be infected by virus,and genetic reassortant could also occur.The spread of AIV not only occurred in a certain migratory routes,but the overlapping of different migration route and the confluence of different migratory birds accelerated the spread of AIV.更多还原