Comparison Of Several Terrestrial Birds To Infections H9N2 Virus

1.Backgroud and ObjectAvian influenza viruses H5N1, H7N9,H9N2 have been circulating in multiple terrestril birds and repeatedly infecting humans, posing a significant threat human health to public health potential in the past ten years. Previous studies sugested that all influenza virus subtypes originated in waterfowl and terrestrial birds might have become intermediate in ecosystems of influenza viruses.After the virus transmitted from waterfowl to land birds, the avain influenza virus adapted to and develop stable lineage and even prevalent in the new host (terrestrial birds).Some studies showed that both SAa2,6Gal and SAa2,3Gal were expressed in terrestrial birds. These findings suggest that terrestrial birds themselves may also act as important intermediate host in ecosystems of influenza viruses to facilitate gene evolution and generate an influenza virus with infecting humans potential.The H9N2 avian influenza virus had become the most widely distributed subtype in china. H9N2 virus transmission route was representative and practical significance, and even played a key role in generation a new avian influenza virus. On the basis of previous study, comparison the difference of replication between chukar and turkey infected by waterfowl duck origin avian and quail-derived avian influenza virus of H9N2. The aim of the study was to explore terrestrial birds played in the role of the evolution and transmission of avian influenza virus, and to provide experimental basis for further screening of the new intermediate host.2 Methods2.1 Experiment in infection of animial:The influenza virus H9N2 was inoculated by the nares, mouth, and eyes in chukar and chicken.2.2 Isolation and identification of influenza virus:The birds were observed daily, and tracheal and cloacal swabs were obtained on days 3,5,7, and detect virus. And then the specimens were inoculated into chicken embryos.The allantoic fluid were collected to detecte the avain influenza virus by hemagglutination test.2.3 TCID50:Specimens of throat swab and cloaca swabs were inoculated in MDCK. The cytopathic effect (CPE) and TCID5o were observed under the microscope to determine whether the samples contain virus and virus virulence.2.4 Pathological changes with the virus infection:Animals infected with viruses was sacrificed. Trachea, bronchus, lung and colon tissue of chukar and chicken were fixed in 10% formalin for 24 hours. Then tissue dehydration, embedding, sectioning, dewaxing to water, H.E. staining and microscopic observation was performed.2.5 Immunohistochemical test to detection of viral antigen:Tissue sections were deparaffinized to the above water, antigen retrieval, seroprotection, then labeled influenza virus antigen.3 Result3.1 H9N2 avain influenza virus DK/ST/3208/2012,which origined from aquatic birds, can replicate in the respiratory tract of chukar,but not to replicate in the chicken.3.2 H9N2 avain influenza virus QA/GX/3139/2012,which origined from terrestrial birds, can replicate in the respiratory tract of chukars,but not to replicate in the chicken.3.3 Chukar inoculated with H9N2 avain influenza virus DK/ST/3208/2012 and QA/GX/3139/2012 can generate inflammation in trachea, bronchus and lung.4 Conclusion4.1 The fact that H9N2 avain influenza virus DK/ST/3208/2012,which origined from aquatic birds, can replicate and generate inflammation in the respiratory tract of chukar show that chukar susceptible to infection avian influenza virus derived from waterfowl.This suggests that the chukar play a important role of intermediate hosts in ecosystems of influenza virus.4.2 The fact that H9N2 avain influenza virus QA/GX/3139/2012, which origined from terrestrial, can replicate and generate inflammation in the respiratory tract of chukar show that chuka susceptible to infection avian influenza virus derived from terrestrial birds. This suggests that the chukar may facilitate viral gene evolution and mutation and generate an influenza virus with infecting mammal and humans potential.4.3 The mainlly replicated site of H9N2 avian influenza virus was in the respiratory tract of chukar.