Monday, November 7, 2011

Rabbit as an Animal Model for Tuberculosis Research

The three main animal models employed for the study of tuberculosis (TB) pathogenesis in humans are rabbits, guinea pigs, and mice. All three of these species have the advantages of closely approximating clinical observations as they can be infected by inhalation, display both innate and adaptive immune responses, and generally control the infection initially before it finally becomes fatal. Human TB pathogenesis is a very complex process and no one animal model represents all aspects of the disease. However, rabbit models of TB have the further advantages of displaying cavitation and arrested infection. [1,2]

Rabbit is the only experimental model in which pulmonary cavitation occurs. Pulmonary cavities in rabbits and humans contain huge populations of TB bacteria (~108), which have access to the bronchial tree and therefore the external environment. Given that the degree of contagiousness of TB in humans is typically judged by bacillary burden in sputum culture, the study of cavitation in rabbits is critical to our understanding of TB transmission in humans. Further, the immune systems of rabbits are capable of arresting infection such that they display a latent, or paucibacillary, state similar to humans and in some cases are capable of controlling TB infection so effectively that the bacilli appear to have been completely cleared. While reactivation from a latent state is spontaneous in humans, rabbit reactivation requires immunosuppression. These features make rabbit an important model for the study of human latent TB. [1,2]

1. Bosze, Z. and Houdebine, L.M. (2006) Application of rabbits in biomedical research: a review. World Rabbit Sci. 14:1-14.
2. Dharmadhikari, A. and Nardell, E.A. (2008) What animal models teach humans about tuberculosis. Am. J. Respir. Cell Mol. Biol. 39:503-508.

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