Irina Franco - Synopsis

"Legionella pneumophila and its host cell targets - what’s the microbiome got to do with it?"

Legionella pneumophila is a facultative intracellular pathogen responsible for Legionnaires’ Disease, a severe type of pneumonia which can develop after the inhalation of contaminated aerosols and infection of lung macrophages.

L. pneumophila is found ubiquitously in freshwater habitats where it parasitizes amoebae, its environmental host. In man-made habitats, these interactions with the surrounding environmental microbiota provide a source of dissemination and trigger virulence traits that aid in subsequent infection of human hosts.

Along millions of years of co-evolution, L. pneumophila has also acquired from this microbiome numerous genetic regions that remain present in the bacterial genome.

These regions evolved to encode effector proteins, which are injected into amoebae and macrophages and play a fundamental role in infection by disrupting the phagolysosomal route that would lead to bacterial degradation. Interestingly, some of these effectors have diverged in function between L. pneumophila strains, such as the recently discovered outbreak strain effector LetN.