An improved protocol to establish experimental tuberculous meningitis in the rabbit

Tuberculous meningitis (TBM), caused by Mycobacterium tuberculosis (Mtb), is the deadliest form of tuberculosis in humans, particularly in children and the geriatric population. However, the host-pathogen interactions underlying TBM is not well understood. Rabbits are a valuable model system to study TB in humans. The rabbit model of TB recapitulates several pathophysiological characteristics, including heterogeneity, architecture, and development of granulomas at the site of infection as observed in Mtb-infected human organs. Previously, our group has established a rabbit model of TBM that has been used to understand the host immune response to Mtb infection and to evaluate novel intervention therapies for TBM. In this model, rabbits infected intracisternally with Mtb showed histopathologic manifestations in the brain and meninges that are hallmarks of TBM in humans, including inflammatory cell accumulation and thickening of the leptomeninges. However, in this model, a helmet made of dental acrylic was attached to rabbit's skull with screws under anesthesia. At 24 h post-procedure, the animals were injected intracisternally with Mtb using a spinal needle. The rabbits were necropsied at various experimental time points up to 2 weeks post-infection. Although this method has been successful in establishing TBM, placement of the dental acrylic helmet on rabbit skull with screws that stays until the experimental endpoint poses stress to the animals and increases the chances of secondary infection. To alleviate these issues, we have developed an improved protocol, in which sedated rabbits are placed on specialised stereotaxic equipment and injected with Mtb intracisternally. This method is less cumbersome, faster, and more efficient in delivering the bacteria. Besides, the animals are not stressed by this method, compared to the previous one.