Infection by Mycobacterium tuberculosis (Mtb) is soon countered by the host's immune system, the organism is however almost never eradicated; ten per cent of infections will develop into "open tuberculosis", while the other ninety per cent become "latent", a state that can persist for decades until loss of immune control. A third of the world's population is estimated to harbour latent tuberculosis. Latent infection involves the bacterium being internalized by macrophages where it stops and counters the innate immune answer (Russell 2011, Russell et al. 2010). When a status-quo is reached, Mtb enters a non-replicating persistent state (Barry et al. 2009, Boshoff & Barry 2005).