[Protective immunity against Mycobacterium tuberculosis].

Mycobacterium tuberculosis (MTB) is an intracellular pathogen that has evolved strategies to enable growth in macrophages. The bacterium is able to inhibit fusion of phagosome with lysosome through secretion of some bacterial components and modulation of host cell intracellular signaling pathways. On the other hand, the complex system of protective immunity is expressed to control bacterial burden in host upon MTB infection. However, virulent MTB is capable of surviving in macrophages in vivo and persists in host even after acquired immunity has developed. These data suggest that MTB has developed a sophisticated immune evasion mechanism. In this issue, host protective response and the strategies of MTB for intracellular survival and immune evasion, which have been unraveled so far, are shown and the mechanisms are discussed.