Some pathogens use temperature as a trigger and activate virulence only after entering the warmer environment of a host. A research team from Ruhr University Bochum, Germany, and the University of Münster, Germany, investigated how a diarrheal pathogen suppresses its virulence outside of the human body. Their study focused on the DNA-binding protein Fis, which is more abundant at cooler ambient temperatures of about 25°C.