A mouse model for latent tuberculosis.

The aim of the study was to establish a reproducible murine model for latent tuberculosis. We propose an operational definition of latent murine tuberculosis as a stable Mycobacterium-tuberculosis count in lungs and spleens without clinical signs or obvious histopathological changes in the lungs over a long period of time and without spontaneous reactivation of disease. B6D2F1Bom mice were inoculated with a wide range of Mycobacterium tuberculosis doses intraperitoneally or intravenously and followed for a long period to determine suitable conditions to produce latent infection. No anti-tuberculosis drug treatment was used. Microbiological and histopathological studies were carried out. Corticosterone challenge was used to reactivate the latent infection. Mice infected with 4 x 10(4) and 4 x 10(5) bacilli i.p. were followed up to 107 weeks without spontaneous reactivation. The present model is discussed in comparison with previous latent tuberculosis mouse models as well as the possible mechanisms of shift to stationary phase from multiplying bacilli.