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From hot dogs to host cells: how the bacterial pathogen Listeria monocytogenes regulates virulence gene expression

Nancy E Freitag

University of Washington, Seattle Biomedical Research Institute and the Departments of Pathobiology and Microbiology, 307 Westlake Avenue N., WA 98109-5219, USA.

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Email the corresponding author at nancy.freitag@sbri.org

Published Online:26 Jun 2006https://doi.org/10.2217/17460913.1.1.89

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Abstract

Environmental pathogens are organisms that normally spend a substantial part of their lifecycle outside of human hosts, but when introduced into humans are capable of causing disease. Such organisms are often able to transition between disparate environments ranging from the soil to the cytosol of host cells. The food-borne bacterial pathogen Listeria monocytogenes serves as a model system for understanding how an environmental organism makes the transition into mammalian hosts. A transcriptional regulatory protein known as PrfA appears to serve as a critical switch, enabling L. monocytogenes to transition from the outside environment to life within the host cell cytosol. PrfA is required for the expression of many L. monocytogenes gene products associated with virulence, and multiple mechanisms serve to regulate the expression and activity of PrfA. Increasing evidence suggests that specific environmental stresses help prime L. monocytogenes for life within the host, and cross-talk between the stress response regulator σ-B and PrfA may mediate the transition from outside environment to cytosol. Once within the host cytosol, multiple changes in bacterial metabolism and gene expression help to complete the transformation of L. monocytogenes from soil dweller to intracellular pathogen.

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Published online 26 June 2006

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Acknowledgements

The author would like to acknowledge the excellent work carried out by many laboratories in the field of L. monocytogenes virulence gene regulation and apologize for any work not mentioned as a result of space considerations. Appreciation is also expressed for excellent comments provided by the reviewers of this manuscript and to Nicholas Cianciotto for helpful discussions. Work was supported by Public Health Service grants AI41816 and AI055651.

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