Objective:To compare the infection of respiratory syncytial virus in common BALB/c mice and nude BALB/c mice to establish ideal animal model.Methods: At various time after RSV infection in BALB/c mice and nude mice

viral titers of lung tissue were assayed by plaque forming experiment

total leukocytes and differential subgroup cells in bronchoalveolar lavage fluid(BALF)were counted.RSV antigens were detected by immunofluorescent assay in BALF and immunohistochemistry in situ of lung tissue

lung histologys were identified by light microscope and electronical microscope assay.Results:RSV was isolated from lung tissue of BALB/c mice and nude mice.RSV antigen was detected by immunofluorescent assay in BALF and by immunohistochemistry in situ of lung tissue in both mouse

furthermore the mean light density of RSV antigen was higher in nude mice(0.277±0.085)than in BALB/c mice(0.128±0.031).The viral titers in both mouse peaked at the 3rd day post infection

and higher viral titer in nude mice than BALB/c mice.The viral titers detecting duration in lung tissue of BALB/c mice and nude mice were respectively 6 days and over 9 days after infection.The total leukocyte number in BALF significantly increased in infected BALB/c mice and nude mice compared with the control mice

and the peaks were the 6th day in BALB/c mice and the 9th day in nude mice.The leukocyte subgroups in turn were lymphocyte

macrophage

neutrophil and eosinophil.Interstitial inflammations with vast lymphocytes infiltrating were identified in lung histology of both mouse.On the 6th day

the more severe inflammation was detected than on the 3rd day.Meanwhile the more heavy inflammation was always found in nude mice than BALB/c mice.Conclusions:The similar RSV infectious characteristic exists between BALB/c mice and nude mice.But the more severe infection happens in nude mice

which benefits to assess the effect of anti-RSV drugs and is ideal mice model of RSV infection.