New paper in mBio: Symbiont-mediated defense against Legionella in amoebae


Lena König and Cecilia Wentrup with members of the symbiosis group headed by Matthias Horn and with researchers from Institut Pasteur and the University of Michigan revealed how chlamydial symbionts protect free-living amoeba from infection with Legionella pneumophila.

Legionella pneumophila is an important human respiratory pathogen that survives and multiplies in biofilms or intracellularly within protists, such as amoebae. Importantly, transmission to humans occurs from these environmental sources. Legionella infection generally leads to rapid host cell lysis. It was therefore surprising to observe that amoebae, including fresh environmental isolates, were well protected during Legionella infection when the bacterial symbiont Protochlamydia amoebophila was also present. Legionella was not prevented from invading amoebae but was impeded in its ability to develop fully virulent progeny and were ultimately cleared in the presence of the symbiont. This study highlights how ecology and virulence of an important human pathogen is affected by a defensive amoeba symbiont, with possibly major consequences for public health.