The Molecular Epidemiology Survey Of Avian Influenza Viruses In Poyang Lake Region During 2015-2016

Objectives:To investigate the prevalence of Avian Influenza Viruses(AIVs)in the poultry farms,live poultry markets and migratory birds habitats of Poyang Lake Region during 2015-2016,study the genetic diversity and origin of the detected avian influenza virus in this year,reveal the AIV transmission cycle between poultry farms,live poultry markets and migratory birds habitats,assess the risk of emerging of the novel avian influenza viruses in the region and ultimately provide some basic research data for AIV ecology research.Methods:Environmental samples were collected from poultry farms,live poultry markets and migratory habitats in Poyang Lake Region during 2015-2016.Embryonated chicken eggs were used to isolate AIV from environmental samples.Real-Time RT-PCR and deep sequencing techniques were used to genotyping and get the whole genome sequence of AIVs.Subsequently,the major HA subtypes,NA subtypes and NS genes were analyzed respectively by site mutation analysis and phylogenetic analysis,and the origin and evolution of viruses were further analyzed.Results:(1)During 2015-2016,23 subtypes of avian influenza viruses were identified.In total 1,100 AIVs were isolated from environmental samples of poultry farms and live poultry markets in Poyang Lake Region,and 22 subtypes AIVs were identified in total.Among them,Influenza H1N3,H2N3 and H4N3 subtype virus were first identified in Poyang Lake Region and H12N2 subtype virus was fist detected in China.H7N9 virus was found in environmental samples in poultry farms.In environmental samples of migratory bird's habitats,7 viruses were identified,including H1N1,H3N2/N6,H5N1 and H5N6 subtype virus.(2)Significant AIV gene flow among live poultry market,migratory bird's habitats and poultry farms,expecially between live poultry market and poultry farms,was observed,some avian influenza viruses such as H1N3,H2N3,H6N2,H6N5,H10N3 and H12N2 subtype avian influeanza were firstly detected to be introduced into the poultry environment in the region.(3)Co-circulation of avian influenza viruses with allele A and B NS gene was detected in this year,the proportion of B alleles is low.(4)S3 IN mutation in M2 protein was found in H5N1,H5N2,H5N6,H7N9 and H9N2 subtype which means these viruses has developed resistance to amantadine.Neuraminidase inhibitor resistant related mutations were found in the neuraminidase of H3N6,H4N6,H5N6,H6N6,H7N3 and H7N9 subtype AIVs,Its biological phenotype needs further verification.Conclusions:During 2015-2016,the environment of poultry farms and live poultry markets in Poyang Lake Region were much heavily polluted by avian influenza viruses than previous years.23 subtypes of avian influenza vinuses were detected in this area and some of them were closely related to the avian influenza viruses circulated in migratory birds of East Asian-Australian Flyway or avian influenza viruses circulated in domestic poultry.The significant virus gene flow between poultry farms and migratory birds habitats were observed.H5N6 and H7N9 subtype avian influenza viruses were detected from environmental samples in local poultry farms,so enhanced biosecurity measures should be used in poultry production and continuous avian influenza virus surveillance should be conducted in this region to provide early warning for human infections with avian influenza viruses.Trans-regional,across-national even across continental avian influenza virus gene flow was detected from some avian influenza virus isolated in this year,which means the avian influenza virus surveillance and prevention needs international cooperation.