Spatial Segregation of Virulence Gene Expression during Acute Enteric Infection with Salmonella enterica serovar Typhimurium Richard C. Laughlin, Leigh A. Knodler, Roula Barhoumi, H. Ross Payne, Jing Wu, Gabriel Gomez, Roberta Pugh, Sara D. Lawhon, Andreas J. Bäumler, Olivia Steele-Mortimer, L. Garry Adams

Salmonella Typhimurium Gram-negative intracellular bacillus Enterobacteriaceae family Non-host specific World: 1.3 billion cases of enteric salmonellosis each year 3 million deaths USA: 1.5 million 500 deaths Recent outbreaks For every case reported about 38 unreported cases occur

Salmonella Typhimurium Environmental Survival pH 4 to 8+ Temp 8° to 45°C Within soil, water, manure, or amoeba Host Survival Temp ~37°C Through alimentary track

Salmonella Typhimurium Found in Ground beef Sushi Sprouts Pet turtles Pigs Chickens Cows

Descriptive Host:Pathogen Interaction Bovine Model 2 or 8h incubation Conditionally expressing GFP Salmonella Fixed and processed for EM or Confocal Post imaging analysis Early (2h) and late (8h) cellular interactions Single cell temporal and spatial distributions

Early (2h) Invasion Cytokeratin 8 PinvF-GFP DNA fliC PinvF-GFP Actin Laughlin et al. mBio 2014 vol5 no1. e000946-13

Early (2h) Invasion Laughlin et al. mBio 2014 vol5 no1. e000946-13

Early Invasion- Host:Pathogen Laughlin et al. mBio 2014 vol5 no1. e000946-13

Temporal & Spatial Distribution Actin GFP Salmonella DNA 2h 8h Distance of PinvF or PssaG positive tissue associated Salmonella to nearest apical surface at 2h or 8h post-infection 8h Laughlin et al. mBio 2014 vol5 no1. e000946-13

Summary Loss of membrane integrity around some intracellular Salmonella including those in extruding epithelial cells. Robust presence of small membrane vesicles originating from host and pathogen. Distinct segregation between SPI1 and SPI2 profiles. SPI1 Salmonella were primarily tissue associated early in infection; predominantly found in epithelium. SPI2 Salmonella found exclusively in late infection samples within lamina propria. Laughlin et al. mBio 2014 vol5 no1. e000946-13