Fig. 1.

Modeling S. Typhi Infection: Human intestinal biopsies are susceptible to Salmonella enterica serovar Typhi infection.

(A) A cartoon schematic detailing the microsnapwell model for infection of human intestinal biopsies. Biopsies are mounted between plastic inserts to preserve orientation by placing the basolateral surface down and the lumen-facing enterocytes in the apical opening. Biopsies are apically treated for 2 h (either media control, STY or STM).

(B) An overview of known STY gene expression prior to and during early invasion. For reference: fliC is the major subunit of flagellin used prior to invasion to facilitate epithelial cell homing and Vi antigen genes tviA and tviB are expressed during invasion.

(C) qPCR gene expression of STY bacteria in our pro-invasion inoculum relative to bacteria grown under traditional laboratory conditions.

(D) Hematoxylin & Eosin and Periodic Acid Schiff images of fixed biopsies. Scale bars represent 500 pixels, “L” indicates the lumen.

(E) Gentamicin protection assay showing the distribution of internalized STY across three donors. Invasion rates varied by donor, data presented represent counts for two separate biopsies from three distinct donors. Invasion rates for STM are 2-3× higher than STY (data not shown).

(F)Invading and intracellular STY are observed by TEM, green arrows. Cytoskeletal rearrangements are denoted by *. Microvillus destruction is marked by red arrows. M cells are marked “M cell,” enterocytes are labeled with “E,” and goblet cells are marked with “G.’ Scale bar is 2um for all TEM images.