Cells within cells: Rickettsiales and the obligate intracellular bacterial lifestyle

The Rickettsiales are a group of obligate intracellular vector-borne Gram-negative bacteria that include many organisms of clinical and agricultural importance, including Anaplasma spp., Ehrlichia chaffeensis, Wolbachia, Rickettsia spp. and Orientia tsutsugamushi. This Review provides an overview of the current state of knowledge of the biology of these bacteria and their interactions with host cells, with a focus on pathogenic species or those that are otherwise important for human health. This includes a description of rickettsial genomics, bacterial cell biology, the intracellular lifestyles of Rickettsiales and the mechanisms by which they induce and evade the innate immune response.

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Acknowledgements

The author apologizes to colleagues whose work could not be cited due to space limitations. J.S. is grateful to the reviewers for their time and effort in carefully reviewing the manuscript, and to past and current laboratory members for scientific contributions. J.S. was funded by a Dorothy Hodgkin Fellowship from the Royal Society and by National Institutes of Health (NIH)/National Institute of Allergy and Infectious Diseases (NIAID) grant 1R21AI144385-01A1.