Effect of microgravity changes on virus infection in mice.

We have analyzed the effect of stress caused by the exposure of BALB/c mice to microgravity change on the susceptibility to herpes simplex virus type 1 (HSV-1) infection. Mice exposed to microgravity for 10 seconds showed a decreased rate of survival from HSV-1 infection. Murine interferon (MuIFN) administration to mice after exposure to microgravity partly diminished the decrease in survival. After repeated exposure to microgravity, mice showed tolerance to the stress. These results indicate that microgravity-stress leads to a down regulation of resistance to virus infection in relation to the modulation of the central nerve system in mice. Responsibility of the immune system dependent on cytokines, including IFN, for down regulation of the resistance is also suggested. Tail-suspended mice were also less resistant to virus infection.