RESUMEN
UNLABELLED: BALB/c mice inoculated intranasally with A/swine/HeBei/012/2008/ (H9N2) virus (SIV), showing acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), were observed for morbidity (lung histopathology, lung coefficient, lung wet/dry weight (W/D) ratio, arterial blood gas characteristics and inflammatory cells in bronchial alveolar lavage fluid (BALF)) and mortality. The results showed that, (1) on days 1-4 post infection (p.i.), mice appeared depressed and showed ruffled fur, reduced food intake, weight loss and hypoxemia with a decreased arterial partial oxygen pressure and an increased partial carbon dioxide pressure. (2) From day 4 p.i., mice began to die and showed pulmonary edema, hemorrhage and inflammatory cells in the alveolar exudate. The lung coefficient and lung W/D ratio significantly increased. (3) On days 3-8 p.i., inflammatory cells, especially alveolar macrophages and polymorphonuclears (PMNs) in BALF significantly increased. (4) The mortality rate reached 62.5%. This study established a successful animal model of ALI induced by infection with H9N2 SIV which may help in further investigations of the pathogenesis of human ALI/ARDS induced by H9N2 SIV infection. KEYWORDS: wine influenza virus; H9N2 subtype; acute lung injury; mouse.