This study investigates the immune response generated by intranasal administration of a live-attenuated BCG strain of Mycobacterium bovis in mice. The research focuses on the activation of T cells and B cells, which are crucial for long-term immunity against mycobacterial infections.
Start with an anesthetized mouse and administer a live-attenuated BCG strain of Mycobacterium bovis, which has reduced disease-causing ability, through the mouse's nose.
The injected bacteria stimulate an immune response in the lung tissue and nearby lymph node.
This leads to the generation of effector T cells and B cells that enter the mouse's circulation.
The effector B cells produce antibodies against mycobacteria.
Meanwhile, the effector T cells settle in the lung tissue as resident memory T cells or TRM cells, providing long-term immunity.
To assess the effectiveness of immunization, administer live, virulent mycobacteria with disease-causing ability through the mouse's nose.
This triggers the activation of TRM cells in the lung tissue.
Activated TRM cells release cytokines, attracting other immune cells, including effector B cells.
These B cells secrete antibodies that bind to mycobacteria, enhancing their clearance by neutrophils, indicating successful immunization.
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 Mycobacterium tuberculosis 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.
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