For intranasal administration, load a micropipette with 20 microliters of the BCG suspension, and place the anesthetized mouse in the supine position inside the hood. Administer the inoculum dropwise between the two nostrils until the entire 20-microliter volume has been deposited, leaving time between the drops to allow the mouse to inhale the suspension. Then, reload the micropipette with another 20 microliters of bacteria and repeat the administration.
For intranasal challenge with the H37Rv Mycobacteriumtuberculosis strain, at the appropriate experimental time point post-vaccination, inoculate the animals with intranasal administration of 40 microliters of the H37Rv bacterial suspension as just demonstrated.