The Surveillance Several Serious Viral Diseases In The Capture Wild Birds And Tigers And The Molecular Basis Of AIV Infection To Tiger

In recently,the number of captured wildlife still increase under the wildlife preservation strategy.Different from free wildlife,the captured wildlife have more chance to contact with humans.However,the research about captured wildlife infectious diseases is rarely.Therefore,we perform the surveillance of avian influenza virus(AIV),new castle disease(NDV),canine distemper virus(CDV),and feline parvovirus(FPV)in captured wild birds and captured wild tigers in wildlife Zoo.Furthermore,we explore the mechanism of the molecular basis of AIV infection to a tiger.To conduct captured wild bird infectious disease surveillance,we collected 960 swab samples and 80 sera samples from wild birds which have been vaccinated with AIV and NDV.One NDV was isolated from the swab samples,however,no AIV were isolated.The sera-positive rate against were 100%,25%,30% against NDV,H5 AIV and H9 AIV respectively.These results indicated that no AIV shedding from vaccinated captured wild birds,however,the low seropositive rate showed that the wild birds couldn't be completely protected by AIV vaccine.The sequencing result showed that the NDV isolate was an attenuated virus.In order to find out the characterization of NDV in wild bird,7 NDV isolated collected form free wild birds were sequenced.The 1 NDV virus of capture wild bird and 7 NDV virus of free wild birds all belonged to Class II of NDV.All 8 viruses were high homologous with attenuated virus.5 of 8 were genotype I,3 of them were genotype II.We perform the serological survey for serious viral diseases of the captive amur tigers such as CDV,NDV,and AIV in the Siberian Tiger Park of Harbin,Changchun,and Shenyang.Our results showed that the serum CPV antibody positive rate of the captive amur tigers was about 100%,while that of the H5 subtype AIV and CDV was 17.24% and 16% respectively,suggesting that these captive amur tigers have the ability against CPV infection,but with a potential for infection with CDV or AIV,or both.We isolated an H5N1 AIV from the tiger,which shows severe clinical signs including fever and dyspnea.The phylogenetic analysis was showed the AIV strain A/Tiger/nanning/01/2015(H5N1)isolated from White Tiger in Nanningzoo can be categorized 2.3.2.1C branch,and each of the eight gene segments has high homology with other H5N1 subtype AIV,there is no genetic reassortment was found.The HA cleavage site was consisting of multiple basic amino acids which was consistent with the characteristics of highly pathogenic AIV.In addition,the HA had 9 potential glycosylation sites,and the receptor-binding site located in 226 was Q,228 was G,resulting from more easily combined to?-2,3receptor.It was found 20 amino acids was deleted in NA located in 49-68 aa.So this change may contribute to expand its host range.Since the 627 aa and 701 aa of PB2 of protein were still E and Q respectively,it was predicted this AIV strain does not have any risk for interspecies transmission.To analyze the transmission mechanism of AIV to a tiger,the receptor binding specification and transmissibility of A/Tiger/nanning/01/2015(H5N1)virus were evaluated.By using sialic acid modified chicken blood cell and glycan,we found the virus only bind ?-2,3 sialic acids(avian-like receptor).The virus could efficiently infect going pigs,however,could not transmit from infected guina pig to na?ve guinea pig.Above results confirmed that tiger could be directly infected by AIV without receptor binding specificity change.Our results indicated that vaccinated method could efficiently reduce the risk of AIV in captured wild bird.The tiger is treated by H5 and H9 subtype AIV.Tiger could be infected by AIV without adapted.The role of the big cat in AIV transmission should be concerned.