Phylogenetic And Molecular Characterization Of Whole Genome Sequences Of An Bean Goose(Anser Fabalis)H6N2 Avian Influenza Virus From Dongting Lake Natural Reserve

Avian Influenza Viruses(AIV)are widely borne in the wild birds.Wild waterfowls are particularly natural reservoirs of AIV Migration of wild birds plays a crucial role in the prevalence of AIV.In total,921 fresh feces samples were collected in the East Dongting Lake National Natural Reserve in December 2014 and February 2015,from which we isolated 38 viruses.Four virus subtypes including H9N2,H6N2,H11N8 and H12N2 were detected.The hosts are Bean Goose(Anser fabalis),White-fronted Goose(Anser albifrons),Swan Goose(Anser cygnoides)and Falcated Duck(Anas falcate).Reverse transcription-polymerase chain reaction(RT-PCR)were used to amplify the full-length viral cDNAs.In this paper,a H6N2 virus isolated from Bean Goose(Anser fabalis)is selected for further analyzed.H6N2 nucleotide sequences were translated into corresponding amino acid sequences for molecular analysis;These sequences were compared with the corresponding sequence published in GenBank and the panorama phylogenetic trees were drawn.Results show that the HA amino acid sequence of the cleavage site is PQIETRIGLF,which is the same as the characteristics of typical low pathogenic avian influenza virus(LPAIV).The receptor related sites show avian influenza virus feature with 226 Q and 228 G The deletion of neck ring of NA amino acid sequence is not observed.The nucleotide sequence homology analysis of PB2,PA and HA gene shows the highest homologies with those from wild waterfowl,while the highest homologies of PB1,NP,NA,M and NS genes are from domestic ducks.Phylogenetic analysis indicated that the PB1,PA,HA,NP,NA,M and NS genes belonged to the Eurasian Gene pool(Group ?,HN573-like)virus lineage,however,PB2 gene is derived from the Gs/GD-like H5N1 virus lineage.Thus,we isolated a natural recombinant H6N2 influenza virus from Bean Goose(Anser fabalis)that was likely acquired genes from isolates of H6N2 and H5N1 subtypes of AIV.Several H6N2 inner genes belong to the same lineages with some isolates of highly pathogenic avian influenza virus(HPAIV)H5N8 that had risen and caused outbreaks of AIV in poultry since 2013.Our finding shows the complicacy as well as the frequency of gene exchange between viruses of different subtypes and hosts during migratory in the East Dongting Lake wetlands,and extends our knowledge of the ecology of AIVs circulating in wild birds.We emphasize the vital need for further surveillance of AIVs in wild birds and poultry to prepare for and respond to potential influenza pandemics in this area.