Animal Model of Respiratory Syncytial Virus Infection in Nude Mice
Abstract: Respiratory syncytial virus ( RSV) is a worldwide leading viral cause of lower respiratory tract infection in children. Immunodeficient individuals are vulnerable to severe RSV infection. No ideal animal model is available at the present time. To establish an ideal murine model, RSV was dripped in tranasally into cellular immunodeficient nude mice, then pulmonary virus was isolated and viral antigen in bronchi-alveolar lavage fluid was identified by direct immunofluorescent assay. Pulmonary viral titers detected by plaque forming assay, peaked on the 3rd day post infection, and were still detectable by the 9th day post infection. RSV antigen was mainly localized in cytoplasm of alveolus and bronchioles by immunohistochemistry assay. RSV infected nude mice developed interstitial pneumonia with prominent lymphocyte infiltration; meanwhile the virus destroyed the air-blood barrier and viral inclusions were found by electron microscopy. The numbers of leukocyte in bronchi-alveolar lavage fluid increased significantly and peaked at the 9th day post infection. All these results indicated that RSV infected nude mice showed similar patterns of viral replication and pulmonary histopathology as with infected humans, and had a high level, durative viral replication. Therefore, RSV infected nude mice appears to be a workable murine model for assessing the effect of antiviral agents against RSV.