Intracellular survival of virulent Mycobacterium bovis and M-bovis BCG in ferret macrophages

The intracellular survival of virulent Mycobacterium bovis and avirulent M. bovis BCG in ferret alveolar macrophages was investigated. In addition, th e effects of endogenous and exogenous modulators of macrophage oxidative fu nction on bacterial survival and growth in vitro were determined. Ferret ma crophages limited the initial growth of BCG, while virulent M. bovis replic ated within macrophages. Intracellular bacterial survival was unaffected by the addition of specific inhibitors of macrophage oxidative function. A T- cell supernatant (TCS), derived from mitogen-stimulated lymphocyte cultures , activated ferret macrophages for heightened oxidative burst performance. However, macrophages activated by TCS, bacterial LPS or a combination of bo th, failed to control infection, and actually enhanced the intracellular su rvival of M. bovis. These results are discussed in relation to the role of macrophages in mediating tuberculosis-related pathogenesis, with respect to the fact that ferrets are important wildlife vectors of bovine tuberculosi s in New Zealand. (C) 1999 Elsevier Science B.V. All rights reserved.