Attenuated Salmonella Typhimurium Lacking the Pathogenicity Island-2 Type 3 Secretion System Grow to High Bacterial Numbers inside Phagocytes in Mice
Figure 5
Phagocyte NADPH oxidase inhibits Salmonella spread in the tissues in the absence of SPI-2 T3SS.
gp91phox−/− mice were infected i.v. with ∼Log10 4.2 CFU ( = 1.45×104 CFU) of S12023 or ∼Log10 4.1 CFU ( = 1.21×104 CFU) of S12023 sseB, C57BL/6 mice were infected i.v. with ∼Log10 4.3 CFU ( = 2.15×104 CFU) of S12023 or ∼Log10 6.4 CFU ( = 2.45×106 CFU) of S12023 sseB. (A) Net bacterial numbers in livers (unbroken lines) and spleens (dotted lines) were determined between 6 and 72 h p.i. inclusive (results are expressed as mean Log10 viable count ± standard deviation), the net bacterial growth of S12023 and S12023 sseB in gp91phox−/− mice was obtained from 3 mice per time point (the data for S12023 and S12023 sseB in C57BL/6 mice is reproduced from Figure 1F. S12023 in C57BL/6 mice – red; S12023 in gp91phox−/− mice – pink; S12023 sseB in C57BL/6 mice – dark blue; S12023 sseB in gp91phox−/− mice – light blue). (B) The proportion of infected phagocytes relative to the numbers of bacteria contained within each phagocyte for S12023 sseB in gp91phox−/− mice and S12023 sseB in C57BL/6 mice at 48 h p.i., based on the counts obtained from 100 infected phagocytes per organ, from tissue obtained from 3 mice per time point. (Livers – fully shaded; Spleens – diagonal shading). (C) Box and whisker plot showing the median, interquartile range and maximum and minimum number of infected cells per field-of-view for S12023 sseB in C57BL/6 mice and S12023 sseB in gp91phox−/− mice at 48 h p.i., from 100 random fields from 3 mice for each strain.