Bacteria induce global inhibition of mRNA translation, which raises the question of how infected cells can launch an effective immune response. In eLife, Vance and colleagues provide support for one possible solution to this conundrum in a model of Legionella infection of macrophages. Through simultaneous measurement of transcriptional activity and translational activity, the authors find that Legionella blocks mainly translation elongation but also, to a lesser extent, translation initiation. In response, the host macrophage undergoes superinduction of mRNA encoding inflammatory mediators such as cytokines, without any obvious evidence for selective gene translation. Certain mRNAs encoding inflammatory molecules can be induced more than 1,000-fold. Collectively, this massive induction of mRNAs has the effect of 'saturating the system' and potentially provides an effective countermeasure to the interference, by bacteria, of host translation.

eLife (6 April 2017) doi:10.7554/eLife.22707