Host-pathogen interactions in latent Mycobacterium tuberculosis infection: identification of new targets for...

Mycobacterium tuberculosis (M. tuberculosis) is one of the worlds' most successful and sophisticated pathogens. It is estimated that over 2 billion people today harbour latent M. tuberculosis infection without any clinical symptoms. Since most new cases of active tuberculosis (TB) arise from this (growing) number of latently infected individuals, urgent measures to control TB reactivation are required, including more effective drugs and new TB vaccines. The currently widely used BCG vaccines, as well as most new generation TB-vaccines that are being developed are designed as prophylactic or as BCG-booster vaccines. Unfortunately, many of these vaccines are unlikely to be effective in individuals already latently infected with M. tuberculosis. Here we argue that detailed analysis of M. tuberculosis genes that are switched on predominantly during the latent stage of infection may lead to the identification of new M. tuberculosis targets for drug and vaccine development. First, we will describe essential host-pathogen interactions in TB with particular emphasis on TB latency and persistent infection. Subsequently, we will focus on a novel group of late-stage specific genes, encoded by the M. tuberculosis dormancy (dosR) regulon, and summarize recent studies describing human T-cell recognition of these dormancy antigens in relation to (latent) M. tuberculosis infection. We will discuss the possible relevance of these new classes of antigens for new TB intervention strategies.