Genome-wide study reveals how key immune sensors arrive at the front lines of infection

In a healthy immune system, invading pathogens trigger a cascade of alerts and responses to fight off the infection. Sensors called toll-like receptors, or TLRs, act as one of the first lines of defense. Two of these sensors, known as TLR7 and TLR9, specifically recognize and respond to microbial RNA and DNA, respectively. But what determines how these TLRs get where they need to be and sound the alarm for pathogen infection?