H9N2 AIV灭活疫苗免疫SPF鸡攻毒后肺组织免疫相关基因表达变化研究.

[Objectives]The aim of this experiment was to explore the effect of H9N2 subtype avian influenza virus attack on the respiratory system of SPF chicken immunized with H9 inactivated vaccine. [Methods]36 SPF chickens were selected and randomly divided into the control group(Con),the challenge group(Flu)and the immunization followed challenge group(Vac+Flu). Chickens were immunized with H9 inactivated vaccine at a dose of 0.4 mL per chicken, and after 3 weeks, they were challenged at a dose of 10~6 EID50 of virus. The swabs, serum, trachea, lung and other samples were collected. Hemagglutination inhibition(HI)antibody titer, the genomes copies of influenza virus M gene and the expression levels of immune related genes CD4,CD8,GATA3,T-bet,IL-4,IL-13,TNF-α,IFN-γ,Perforin,Granzyme,FasL,Fas were separately detected by HI assay, RT-PCR and quantitative PCR(qPCR). And the pathological changes and distribution of virus specific antigen NP protein of trachea and lung were individually observed by hematoxylin-eosin staining and immunohistochemistry. [Results]The results of HI assay showed that SPF chicken could produce high H9N2 AIV antibody titer after immunization. The results of immune protection test and RT-PCR showed that the virus shedding and the expression of influenza virus M gene in lung tissue could still be detected after SPF chickens were immunized with vaccine and followed by viral infection. The result of hematoxylin-eosin staining and immunohistochemistry showed that inoculating the H9N2 AIV inactivated vaccine significantly alleviated the pathological damage of trachea and lung and significantly reduced the viral load of trachea and lung. Quantitative PCR showed that inoculating the H9N2 AIV inactivated vaccine significantly up-regulated the secretion of Th1 and Th2 cytokines and promoted the expression of perforin/granzyme pathway related genes to enhance cytotoxicity in the lung. [Conclusions]Although chickens inoculated with H9N2 vaccine were infected with H9 virus, there was still a phenomenon of virus shedding. Their antiviral immune system was active and the viral load of main organs was reduced. It is recommended to carry out vaccination according to the influenza vaccine immunization procedure to improve the level of influenza prevention. [ABSTRACT FROM AUTHOR]