Surviving the Macrophage: Tools and Tricks Employed by Mycobacterium tuberculosis

Mycobacterium tuberculosis has evolved to withstand one of the most inhospitable cells within the human body, namely the macrophage, a cell that is normally geared toward the destruction of any invading microbe. How M. tuberculosis achieves this is still incompletely understood; however, a number of mechanisms are now known that provide advantages to M. tuberculosis for its survival and proliferation inside the macrophage. While some of these mechanisms are mediated by factors released by M. tuberculosis, others rely on host components that are being hijacked to benefit survival of M. tuberculosis within the macrophage as well to avoid the generation of an effective immune response. Here, we describe several of these mechanisms, also pointing out the potential usage of this knowledge toward the development of novel strategies to treat tuberculosis. Furthermore, we attempt to put the 'macrophage niche' into context with other intracellular pathogens and discuss some of the generalities as well as specializations that M. tuberculosis employs to survive.