| Recently, the waterfowl infection ratio of low pathogenic H9N2avian influenza virus (AIV) has been increased each year. Thus, it is essential to prevent and control H9N2AIV in the waterfowl. However, the absence of functional H9N2AIV vaccine becomes a worldwide problem. The promise to solve this problem is to establish H9N2AIV infection model for waterfowl.Using chicken embryo purification,3H9N2subtype AIVs were selected and identified. These3H9N2AIVs and2H9N2subtype AIVs purified in the previous study intravenously infected5w ducks:106.0EID50/100μL in a dose,100μL/duck,2ducks each virus. At the1-5days post-infection (dpi), pharyngeal swabs and cloacal swabs were collected to isolate viruses. The result demonstrated that the infection ratio of SH441was the highest (100%) compared to those of other H9N2subtype AIVs, and SH441could replicate well in the ducks in vivo; The virus could be dectected in the pharyngeal swabs, but not in the cloacal swabs. Large scale of ducks was infected with SH441. At the3dpi,3ducks were killed and collected8tissues to measure virus titers, including of lung, trachea, heart, liver, spleen, kidney, brain and pancreas. At the1-5dpi, pharyngeal swabs were collected and determined virus titers. The result demonstrated that duck infection ratio was100%, and the same as those in the small quantity of duck experiment. At the1dpi or3dpi, virus could be detected in the pharyngeal swabs, but no virus later. Moreover, SH441could also replicate in vivo, such as lung, trachea and pancreas. Thus, we preliminarily establish H9N2AIV infection model for ducks:intravenously infected with a dose of106.0EID50/100μL,100μL/duck; at the1or3dpi, pharyngeal swabs were collected to isolate virus. This infection model was used to evaluate vaccine immunization effect on ducks.The result demonstrated SH441inactivated vaccine could prevent SH441to infect ducks and the protection ratio was100%. In a word, H9N2AIV infection model for duck is established and could evaluate vaccine assessment successfully. It provides a foundation for the study of effective H9N2AIV vaccines for waterfowl in the future. |
