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Independent bottlenecks characterize colonization of systemic compartments and gut lymphoid tissue by salmonella.

Lim CH, Voedisch S, Wahl B, Rouf SF, Geffers R, Rhen M, Pabst O - PLoS Pathog. (2014)

Bottom Line: We established a next generation sequencing based method to characterize the composition of tagged Salmonella strains which offers a fast and reliable method to characterise the composition of genome-tagged Salmonella strains.Colonization of Peyer's patches fuels the sustained spread of bacteria into mesenteric lymph nodes via dendritic cells.Vaccination only moderately reduced invasion of Peyer's patches but potently uncoupled bacterial populations present in different systemic compartments.

View Article: PubMed Central - PubMed

Affiliation: Institute of Immunology, Hannover Medical School, Hannover, Germany.

ABSTRACT
Vaccination represents an important instrument to control typhoid fever in humans and protects mice from lethal infection with mouse pathogenic serovars of Salmonella species. Mixed infections with tagged Salmonella can be used in combination with probabilistic models to describe the dynamics of the infection process. Here we used mixed oral infections with tagged Salmonella strains to identify bottlenecks in the infection process in naïve and vaccinated mice. We established a next generation sequencing based method to characterize the composition of tagged Salmonella strains which offers a fast and reliable method to characterise the composition of genome-tagged Salmonella strains. We show that initial colonization of Salmonella was distinguished by a non-Darwinian selection of few bacteria setting up the infection independently in gut associated lymphoid tissue and systemic compartments. Colonization of Peyer's patches fuels the sustained spread of bacteria into mesenteric lymph nodes via dendritic cells. In contrast, infection of liver and spleen originated from an independent pool of bacteria. Vaccination only moderately reduced invasion of Peyer's patches but potently uncoupled bacterial populations present in different systemic compartments. Our data indicate that vaccination differentially skews the capacity of Salmonella to colonize systemic and gut immune compartments and provide a framework for the further dissection of infection dynamics.

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Vaccination modulates routes of S. Typhimurium dissemination.Mice were vaccinated with a SL1344ΔaroA strain 40–50 days or left untreated before infection with the WITS library. WITS composition was determined as described in Fig. 3A. (A) Pie diagrams depict representative examples of WITS composition in pooled PP, mLN, liver and spleen of one non-vaccinated and one vaccinated mouse. (B) Similarity of WITS composition was compared between various compartments. Numbers indicate MHI for the various comparisons and line width/style depicts MHI as indicated in Fig. 4B. 2-way ANOVA reveals that the effect of vaccination on the similarity between compartments (determined by MHI) is significant (p<0.001). Mann-Whitney t test revealed significant effects on distinct compartments. Vaccination significantly affected similarity of the WITS composition between PP and mLN (p = 0.016), mLN and liver (p = 0.026), mLN and spleen (p = 0.016) and liver and spleen (p = 0.004). Vaccination had no significant effect on the similarity in WITS composition observed for the comparison of PP and liver or PP and spleen. (C) Vaccination only moderately reduced invasion of PP. Symbols indicate TSU predicted for individual PP, mLN, liver and spleen of non-vaccinated and vaccinated mice pooled from 3 or more independent experiments. Horizontal bars indicate the mean.
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ppat-1004270-g006: Vaccination modulates routes of S. Typhimurium dissemination.Mice were vaccinated with a SL1344ΔaroA strain 40–50 days or left untreated before infection with the WITS library. WITS composition was determined as described in Fig. 3A. (A) Pie diagrams depict representative examples of WITS composition in pooled PP, mLN, liver and spleen of one non-vaccinated and one vaccinated mouse. (B) Similarity of WITS composition was compared between various compartments. Numbers indicate MHI for the various comparisons and line width/style depicts MHI as indicated in Fig. 4B. 2-way ANOVA reveals that the effect of vaccination on the similarity between compartments (determined by MHI) is significant (p<0.001). Mann-Whitney t test revealed significant effects on distinct compartments. Vaccination significantly affected similarity of the WITS composition between PP and mLN (p = 0.016), mLN and liver (p = 0.026), mLN and spleen (p = 0.016) and liver and spleen (p = 0.004). Vaccination had no significant effect on the similarity in WITS composition observed for the comparison of PP and liver or PP and spleen. (C) Vaccination only moderately reduced invasion of PP. Symbols indicate TSU predicted for individual PP, mLN, liver and spleen of non-vaccinated and vaccinated mice pooled from 3 or more independent experiments. Horizontal bars indicate the mean.

Mentions: When infecting vaccinated and non-vaccinated mice with the WITS library and probing proportions of WITS 2 days post infection, uneven WITS composition and holes in the WITS library were observed in mLN, liver and spleen of both vaccinated and non-vaccinated mice (Fig. 6A and S4). When comparing the WITS composition between various compartments in non-vaccinated mice, the highest MHI were observed at PP to mLN and liver to spleen comparisons (Fig. 6B and S4). In contrast, the WITS composition in PP and mLN was largely dissimilar to the composition noted for the liver and spleen. This indicates that S. Typhimurium colonizing systemic compartments did not originate from PP or mLN. Consistently, we observed that depletion of CD11c-expressing cells resulted in decreased TSU in mLN but not in liver and spleen (Fig. S5). Depletion of CD11c-expressing cells foremost affects dendritic cell (DC) numbers. Thus, reduced TSU after DC depletion in mLN but not systemic compartments supports our previous suggestion that dissemination from gut/PP to mLN but not to liver and spleen relies on DC-mediated transport of Salmonella[22]. Instead, colonization of liver and spleen seems to originate from an independent pool of bacteria.


Independent bottlenecks characterize colonization of systemic compartments and gut lymphoid tissue by salmonella.

Lim CH, Voedisch S, Wahl B, Rouf SF, Geffers R, Rhen M, Pabst O - PLoS Pathog. (2014)

Vaccination modulates routes of S. Typhimurium dissemination.Mice were vaccinated with a SL1344ΔaroA strain 40–50 days or left untreated before infection with the WITS library. WITS composition was determined as described in Fig. 3A. (A) Pie diagrams depict representative examples of WITS composition in pooled PP, mLN, liver and spleen of one non-vaccinated and one vaccinated mouse. (B) Similarity of WITS composition was compared between various compartments. Numbers indicate MHI for the various comparisons and line width/style depicts MHI as indicated in Fig. 4B. 2-way ANOVA reveals that the effect of vaccination on the similarity between compartments (determined by MHI) is significant (p<0.001). Mann-Whitney t test revealed significant effects on distinct compartments. Vaccination significantly affected similarity of the WITS composition between PP and mLN (p = 0.016), mLN and liver (p = 0.026), mLN and spleen (p = 0.016) and liver and spleen (p = 0.004). Vaccination had no significant effect on the similarity in WITS composition observed for the comparison of PP and liver or PP and spleen. (C) Vaccination only moderately reduced invasion of PP. Symbols indicate TSU predicted for individual PP, mLN, liver and spleen of non-vaccinated and vaccinated mice pooled from 3 or more independent experiments. Horizontal bars indicate the mean.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4117638&req=5

ppat-1004270-g006: Vaccination modulates routes of S. Typhimurium dissemination.Mice were vaccinated with a SL1344ΔaroA strain 40–50 days or left untreated before infection with the WITS library. WITS composition was determined as described in Fig. 3A. (A) Pie diagrams depict representative examples of WITS composition in pooled PP, mLN, liver and spleen of one non-vaccinated and one vaccinated mouse. (B) Similarity of WITS composition was compared between various compartments. Numbers indicate MHI for the various comparisons and line width/style depicts MHI as indicated in Fig. 4B. 2-way ANOVA reveals that the effect of vaccination on the similarity between compartments (determined by MHI) is significant (p<0.001). Mann-Whitney t test revealed significant effects on distinct compartments. Vaccination significantly affected similarity of the WITS composition between PP and mLN (p = 0.016), mLN and liver (p = 0.026), mLN and spleen (p = 0.016) and liver and spleen (p = 0.004). Vaccination had no significant effect on the similarity in WITS composition observed for the comparison of PP and liver or PP and spleen. (C) Vaccination only moderately reduced invasion of PP. Symbols indicate TSU predicted for individual PP, mLN, liver and spleen of non-vaccinated and vaccinated mice pooled from 3 or more independent experiments. Horizontal bars indicate the mean.
Mentions: When infecting vaccinated and non-vaccinated mice with the WITS library and probing proportions of WITS 2 days post infection, uneven WITS composition and holes in the WITS library were observed in mLN, liver and spleen of both vaccinated and non-vaccinated mice (Fig. 6A and S4). When comparing the WITS composition between various compartments in non-vaccinated mice, the highest MHI were observed at PP to mLN and liver to spleen comparisons (Fig. 6B and S4). In contrast, the WITS composition in PP and mLN was largely dissimilar to the composition noted for the liver and spleen. This indicates that S. Typhimurium colonizing systemic compartments did not originate from PP or mLN. Consistently, we observed that depletion of CD11c-expressing cells resulted in decreased TSU in mLN but not in liver and spleen (Fig. S5). Depletion of CD11c-expressing cells foremost affects dendritic cell (DC) numbers. Thus, reduced TSU after DC depletion in mLN but not systemic compartments supports our previous suggestion that dissemination from gut/PP to mLN but not to liver and spleen relies on DC-mediated transport of Salmonella[22]. Instead, colonization of liver and spleen seems to originate from an independent pool of bacteria.

Bottom Line: We established a next generation sequencing based method to characterize the composition of tagged Salmonella strains which offers a fast and reliable method to characterise the composition of genome-tagged Salmonella strains.Colonization of Peyer's patches fuels the sustained spread of bacteria into mesenteric lymph nodes via dendritic cells.Vaccination only moderately reduced invasion of Peyer's patches but potently uncoupled bacterial populations present in different systemic compartments.

View Article: PubMed Central - PubMed

Affiliation: Institute of Immunology, Hannover Medical School, Hannover, Germany.

ABSTRACT
Vaccination represents an important instrument to control typhoid fever in humans and protects mice from lethal infection with mouse pathogenic serovars of Salmonella species. Mixed infections with tagged Salmonella can be used in combination with probabilistic models to describe the dynamics of the infection process. Here we used mixed oral infections with tagged Salmonella strains to identify bottlenecks in the infection process in naïve and vaccinated mice. We established a next generation sequencing based method to characterize the composition of tagged Salmonella strains which offers a fast and reliable method to characterise the composition of genome-tagged Salmonella strains. We show that initial colonization of Salmonella was distinguished by a non-Darwinian selection of few bacteria setting up the infection independently in gut associated lymphoid tissue and systemic compartments. Colonization of Peyer's patches fuels the sustained spread of bacteria into mesenteric lymph nodes via dendritic cells. In contrast, infection of liver and spleen originated from an independent pool of bacteria. Vaccination only moderately reduced invasion of Peyer's patches but potently uncoupled bacterial populations present in different systemic compartments. Our data indicate that vaccination differentially skews the capacity of Salmonella to colonize systemic and gut immune compartments and provide a framework for the further dissection of infection dynamics.

Show MeSH
Related in: MedlinePlus