Bacterial Puppeteering: How the Stealth Bacterium Coxiella Pulls the Cellular Strings

Coxiella burnetii, the causative agent of Q fever, is a highly infectious pathogen capable of invading diverse cell types, from alveolar macrophages to trophoblasts. Within host cells, it establishes a replicative niche named Coxiella-containing vacuole (CCV). This is driven by effector proteins secreted by the bacterium into the host cell cytoplasm via a Type 4b Secretion System (T4SS). Advances in axenic culture and mutagenesis allowed the characterization of Coxiella effector proteins, revealing their host targets and strategies of cellular subversion. This review highlights recent insights into Coxiella effector proteins and their manipulation of host processes, from vesicular trafficking to innate immunity.