Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) is a common cause of enterocolitis in humans and cattle but causes a systemic, typhoid-like, disease in susceptible mice. This facultative intracellular pathogen invades non-phagocytic cells, particularly intestinal epithelial cells. Interactions with epithelial cells are largely mediated by two type III secretion systems (T3SS1 and T3SS2), which translocate distinct cohorts of bacterial effector proteins into the host cell. Following internalization, which is mediated effectors translocated by T3SS1, the bacteria are localized within a modified phagosome, known as the Salmonella-containing vacuole (SCV). Maturation of the SCV is mediated by effectors translocated by T3SS2. Intracellular replication occurs within the SCV and within the cytosol, bacterial growth rates and transcriptional status within these two intracellular niches are quite different. In particular, the T3SS1 is functionally active in the cytosolic bacteria whereas the T3SS2 is functionally active in the vacuolar bacteria. Thus, each of the T3SS systems are functional in the intracellular environment albeit in different niches. We are dissecting the roles of these two secretion systems both in vitro and in vivo.

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Lathrop, Stephanie K; Cooper, Kendal G; Binder, Kelsey A et al. (2018) Salmonella Typhimurium Infection of Human Monocyte-Derived Macrophages. Curr Protoc Microbiol 50:e56
Finn, Ciaran E; Chong, Audrey; Cooper, Kendal G et al. (2017) A second wave of Salmonella T3SS1 activity prolongs the lifespan of infected epithelial cells. PLoS Pathog 13:e1006354
Cooper, Kendal G; Chong, Audrey; Starr, Tregei et al. (2017) Predictable, Tunable Protein Production in Salmonella for Studying Host-Pathogen Interactions. Front Cell Infect Microbiol 7:475
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Sridhar, Sushmita; Steele-Mortimer, Olivia (2016) Inherent Variability of Growth Media Impacts the Ability of Salmonella Typhimurium to Interact with Host Cells. PLoS One 11:e0157043
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Knodler, Leigh A; Nair, Vinod; Steele-Mortimer, Olivia (2014) Quantitative assessment of cytosolic Salmonella in epithelial cells. PLoS One 9:e84681
Jolly, Carrie; Winfree, Seth; Hansen, Bryan et al. (2014) The Annexin A2/p11 complex is required for efficient invasion of Salmonella Typhimurium in epithelial cells. Cell Microbiol 16:64-77
Steele-Mortimer, Olivia; Subtil, Agathe (2014) Editorial overview: Host-microbe interactions: bacteria. War and peace: the fragile equilibrium between bacteria and host. Curr Opin Microbiol 17:v-vii
Malik-Kale, Preeti; Winfree, Seth; Steele-Mortimer, Olivia (2012) The bimodal lifestyle of intracellular Salmonella in epithelial cells: replication in the cytosol obscures defects in vacuolar replication. PLoS One 7:e38732

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