Infection of respiratory syncytial virus in BALB/c mice and nude mice

Objective To compare respiratory syncytial virus(RSV)infection and inflammatory responses between immunocompetent BALB/c mice and immanodeficient nude mice.Methods At various time points after BSV infection of BALB/c mice and nude mice,pulmonary viral titers were assayed.Leukocvtes in bronchoalveolar lavage fluid(BALF)and pulmonary histology were identified.F4/80+cells and CD49b+cells in lung tissue were examined by immunohistochemistry,and the cytokines of TNF-α,IL-12,IFN-r and IL-10 in BALF were assayed by ELISA.Results RSV titers in infected BALB/c mice and nude mice peaked on the 3rd day postinoculation,and nude mice had higher-level and more durative viral replication than BALB/c mice.RSV infection induced more severe pulmonary histopathology and larger number of leukocytes in airway in nude mice than in BALB/c mice.RSV infection enhanced more pulmonary F4/80+macrophages,CD49b+ NK cells in both mice.Furthermore infected nude mice had larger amount of pulmonary macrophages and NK cells than infected BALB/c mice.RSV infected BALB/c mice secreted more TNF-α,IL-12,IFN-r and IL-10 as compared with control BALB/c mice,and infected nude mice had hisher level of TNF-α.IL-12 and IL-10 than infected BALB/c mice.Conclusion Nude mice are good model for severe and pemistent RSV infection in immunocomprised hosts.The inflammation induced by RSV infection is not parallel with the immune response of T cells,and macrophages and NK cells are potent immunocytes and inflammatory cells in RSV infection especially when T lymphocytes are absent. Key words: Respiratory syncytial virus; Inflammation; Immunity