Amoebas are free-living, single-celled organisms, but they have some things in common with some cells of our immune system (macrophages). For example, certain bacterial pathogens can infect both in similar ways. So it can be useful to study the interactions of amoebas and bacteria to learn about our own immune defenses.

In this study, the amoeba Acanthamoeba castellanii has another bacterial symbiont that helps it resist killing by the bacterial pathogen Legionella pneumophila. Once the amoebas recovered from the infection, they were more resistant to future challenges. Even better, the symbiont prevented the pathogen from transforming into a more spreadable form like it does when infecting amoebas alone.

König L, Wentrup C, Schulz F, Wascher F, Escola S, Swanson MS, Buchrieser C, Horn M. 2019. Symbiont-Mediated Defense against Legionella pneumophila in Amoebae. mBio 10:e00333-19.