Study On Temporal And Spatial Relationship Between Bar-headed Goose And Avian Influenza Virus On Qinghai-Tibet Plateau

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.