Efficacy of inactivated vaccine against H5N1 influenza virus infection in mice with type 1 diabetes

We sought to determine susceptibility to highly pathogenic avian influenza (HPAI) H5N1 virus and to explore immune protection of inactivated H5N1 vaccine in streptozotocin-induced type 1 diabetic mice. Susceptibility of diabetic mice to an H5N1 virus was evaluated by comparing the median lethal dose (LD₅₀) and the lung virus titers with those of the healthy after the viral infection. To evaluate the influence of diabetes on vaccination, diabetic and healthy mice were immunized once with an inactivated H5N1 vaccine and then challenged with a lethal dose of H5N1 virus. The antibody responses, survival rates, lung virus titers and body weight changes were tested. Mice with type 1 diabetes had higher lung virus titers and lower survival rates than healthy mice after H5N1 virus infection. Inactivated H5N1 vaccine induced protective antibody in diabetic mice, but the antibody responses were postponed and weakened. In spite of this, diabetic mice could be protected against the lethal virus challenge by a single dose of immunization when the amount of the antigen increased. These results indicated that type 1 diabetic mice were more susceptible to H5N1 influenza virus infection than healthy mice, and can be effectively protected by inactivated H5N1 vaccine with increased antigen.