[Immunization efficacy and safety of 104M against aerosol challenge in BALB/c mice].

To evaluate the protective efficacy and safety of 104M against aerosol challenge in BALB/c mice and characterize its immunological effects. Female mice of 6-8 weeks old were immunized with strain 104M by intratracheal aerosol delivery or intranasal instillation or subcutaneous injection route. Six mice of each group were sacrificed at 4, 8, 16, 24 weeks after immunization. At each time point, the clinical manifestations of mice were investigated, the serum, spleen and lung samples of mice were collected, body weight, spleen weight, bacteria loads in spleens, the anti- antibodies titers in serum and the cytokines concentrations of IFN-γ, IL-18 in serum or lung homogenate of the mice were detected. Twenty two weeks after immunization, all the mice were challenged with A19 through intratracheal aerosol delivery. Compared with the control group, neither abnormal clinical symptoms nor significant changes in body weight were found in 104M immunization groups, at each time point when immunized through either nose dropping route, subcutaneous injection or aerosol routes; and the spleen weight of immunization groups were lower than control group after challenge (<0.05): *M1 (0.26±0.16)g