Fig. 2.

(A) Detection of Vi antigen expression in vivo by immunofluorescence in the liver at 30 min postinfection. The panels represent different channels: green, GFP⁺ Salmonella; red, Vi; blue, nucleic acid (indicated by DAPI staining). A merged image is shown at bottom right. Bars, 7.5 μm. (B) Percentages of C5.507 GFP⁺ bacteria expressing Vi antigen in vivo in livers (black bars) and spleens (white bars) at 0.5 h, 6 h, 24 h, and 96 h p.i. Results are expressed as mean percentages of C5.507 GFP⁺ bacteria expressing Vi antigen ± standard deviations (n = 4 mice per group; a total of 200 bacteria were counted per organ and per time point). (C) Means and adjusted 95% CIs for the differences between the percentages of Vi⁺ bacteria at consecutive time points (shown in panel B). If the CIs do not cross zero, then they are equivalent to ascertaining statistical significance. Gray lines correspond to increments of 20%.