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. 2021 Mar 2;17(3):e1009345. doi: 10.1371/journal.ppat.1009345

Fig 1. Salmonella Typhi Vi capsule expression is elevated after shift from ambient to human body temperature.

Fig 1

A) Immunofluorescence microscopy images of wild-type (WT) or Vi capsule deficient (ΔtviA) S. Typhi Ty2 grown at 23°C (upper panels) or grown at 23°C and shifted to 37°C for 2 hours (lower panels). Bacteria were stained using Vi capsule-specific antibody (red) and DAPI counterstain (blue). Merged images show zoomed in insets of bacteria. Scale bar = 20 μm. B) Vi capsule expression measured by flow cytometry of wild-type (WT) or ΔtviA S. Typhi grown at 23°C or after a 30 minute shift to 37°C. C) Percentage of Vi+ WT or ΔtviA S. Typhi bacteria grown at 23°C or after a 30 minute shift to 37°C as measured by flow cytometry. D) Relative expression levels of tviA mRNA of WT and ΔtviA S. Typhi at ambient temperature (23°C) or following a shift to human body temperature (37°C) for 30 minutes. tviA mRNA levels normalized to 16S mRNA levels. ΔΔCt method used to determine relative expression compared to WT at 23°C. Data shown are representative of 3 (A and B) independent experiments or are the combined results of 3 (C) or 2 (D) independent experiments with triplicate samples for each condition. Symbol shape corresponds with datapoints from different independent experiments. Data are represented as mean ± SD. ND, not detected. NS, not significant. Significance calculated using two-way ANOVA with Tukey’s correction. *** p < 0.001, **** p < 0.0001.