title: Long-term live-cell imaging reveals new roles for Salmonella effector proteins SseG and SteA.
abstract: Salmonella Typhimurium is an intracellular bacterial pathogen that infects both epithelial cells and macrophages. Salmonella effector proteins, which are translocated into the host cell and manipulate host cell components, control the ability to replicate and/or survive in host cells. Due to the complexity and heterogeneity of Salmonella infections, there is growing recognition of the need for single-cell and live-cell imaging approaches to identify and characterize the diversity of cellular phenotypes and how they evolve over time. Here, we establish a pipeline for long-term (17 h) live-cell imaging of infected cells and subsequent image analysis methods. We apply this pipeline to track bacterial replication within the Salmonella-containing vacuole in epithelial cells, quantify vacuolar replication versus survival in macrophages and investigate the role of individual effector proteins in mediating these parameters. This approach revealed that dispersed bacteria can coalesce at later stages of infection, that the effector protein SseG influences the propensity for cytosolic hyper-replication in epithelial cells, and that while SteA only has a subtle effect on vacuolar replication in epithelial cells, it has a profound impact on infection parameters in immunocompetent macrophages, suggesting differential roles for effector proteins in different infection models.
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: McQuate
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Young
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Silva-Herzog
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Bunker
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Mateo
authors.initials: M
authors.lastname: Hernandez
authors.affiliation: Unité d'Analyse d'Images Quantitative, Institut Pasteur, Paris, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: de Chaumont
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Xuedong
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Corrella S
authors.initials: CS
authors.lastname: Detweiler
authors.affiliation: Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Palmer
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004847:Epithelial Cells / Q000382:microbiology*; D007091:Image Processing, Computer-Assisted; D008264:Macrophages / Q000382:microbiology*; D050296:Microbial Viability; D061848:Optical Imaging; D012486:Salmonella typhimurium / Q000254:growth & development / Q000472:pathogenicity*; D059010:Single-Cell Analysis; D014617:Vacuoles / Q000382:microbiology*; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C000621621:SseG protein, Salmonella typhimurium; C000590973:SteA protein, Salmonella typhimurium; D037521:Virulence Factors