Role of the alternative sigma factors σ E and σ S in survival of Salmonella enterica serovar Typhimurium during starvation, refrigeration and osmotic shock

ABSTRACT Toll-like receptors (TLRs) play an important role in the innate immune response, particularly in the initial interaction between the infecting microorganism and phagocytic cells, such as macrophages. We investigated the role of TLR4 during infection of primary murine peritoneal macrophages with Salmonella enterica serovar Typhimurium. We found that macrophages from the C3H/HeJ mouse strain, which carries a functionally inactive Tlr4 gene, exhibit marked impairment of tumor necrosis factor alpha (TNF-α) secretion in response to S. enterica serovar Typhimurium infection. However, activation of extracellular growth factor-regulated kinase and NF-κB signaling pathways was relatively unaffected, as was increased expression of TNF-α mRNA. Furthermore, macrophage tolerance, which is associated with increased expression of the NF-κB p50 and p52 subunits, was induced by S. enterica serovar Typhimurium even in the absence of functional TLR4. These results indicate that during infection of macrophages by S. enterica serovar Typhimurium, TLR4 signals are required at a posttranscriptional step to maximize secretion of TNF-α. Signals delivered by pattern recognition receptors other than TLR4 are sufficient for the increased expression of the TNF-α transcript and at least some genes associated with macrophage tolerance.

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Flagella and Chemotaxis Are Required for Efficient Induction of Salmonella enterica Serovar Typhimurium Colitis in Streptomycin-Pretreated Mice

Infection and Immunity ◽

10.1128/iai.72.7.4138-4150.2004 ◽

2004 ◽

Vol 72 (7) ◽

pp. 4138-4150 ◽

Cited By ~ 210

Author(s):

Bärbel Stecher ◽

Siegfried Hapfelmeier ◽

Catherine Müller ◽

Marcus Kremer ◽

Thomas Stallmach ◽

...

Keyword(s):

Virulence Factors ◽

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Innate Immune ◽

Gastrointestinal Infections ◽

Infection Models ◽

Serovar Typhimurium ◽

Efficient Induction ◽

Toll Like Receptor 5

ABSTRACT Salmonella enterica subspecies 1 serovar Typhimurium is a common cause of gastrointestinal infections. The host's innate immune system and a complex set of Salmonella virulence factors are thought to contribute to enteric disease. The serovar Typhimurium virulence factors have been studied extensively by using tissue culture assays, and bovine infection models have been used to verify the role of these factors in enterocolitis. Streptomycin-pretreated mice provide an alternative animal model to study enteric salmonellosis. In this model, the Salmonella pathogenicity island 1 type III secretion system has a key virulence function. Nothing is known about the role of other virulence factors. We investigated the role of flagella in murine serovar Typhimurium colitis. A nonflagellated serovar Typhimurium mutant (fliGHI) efficiently colonized the intestine but caused little colitis during the early phase of infection (10 and 24 h postinfection). In competition assays with differentially labeled strains, the fliGHI mutant had a reduced capacity to get near the intestinal epithelium, as determined by fluorescence microscopy. A flagellated but nonchemotactic cheY mutant had the same virulence defects as the fliGHI mutant for causing colitis. In competitive infections, both mutants colonized the intestine of streptomycin-pretreated mice by day 1 postinfection but were outcompeted by the wild-type strain by day 3 postinfection. Together, these data demonstrate that flagella are required for efficient colonization and induction of colitis in streptomycin-pretreated mice. This effect is mostly attributable to chemotaxis. Recognition of flagellar subunits (i.e., flagellin) by innate immune receptors (i.e., Toll-like receptor 5) may be less important.

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The enzyme phosphoglucomutase (Pgm) is required by Salmonella enterica serovar Typhimurium for O-antigen production, resistance to antimicrobial peptides and in vivo fitness

Microbiology ◽

10.1099/mic.0.029553-0 ◽

2009 ◽

Vol 155 (10) ◽

pp. 3403-3410 ◽

Cited By ~ 22

Author(s):

G. K. Paterson ◽

D. B. Cone ◽

S. E. Peters ◽

D. J. Maskell

Keyword(s):

Antimicrobial Peptides ◽

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Live Attenuated Vaccine ◽

Antigen Production ◽

O Antigen ◽

Serovar Typhimurium

The enzyme phosphoglucomutase (Pgm) catalyses the interconversion of glucose 1-phosphate and glucose 6-phosphate and contributes to glycolysis and the generation of sugar nucleotides for biosynthesis. To assess the role of this enzyme in the biology of the pathogen Salmonella enterica serovar Typhimurium we have characterized a pgm deletion mutant in strain SL1344. Compared to SL1344, SL1344 pgm had impaired growth in vitro, was deficient in the ability to utilize galactose as a carbon source and displayed reduced O-antigen polymer length. The mutant was also more susceptible to antimicrobial peptides and showed decreased fitness in the mouse typhoid model. The in vivo phenotype of SL1344 pgm indicated a role for pgm in the early stages of infection, most likely through deficient O-antigen production. Although pgm mutants in other pathogens have potential as live attenuated vaccine strains, SL1344 pgm was not sufficiently attenuated for such use.

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Characterization and role of Peptidase N from Salmonella enterica serovar Typhimurium

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2006.12.073 ◽

2007 ◽

Vol 353 (3) ◽

pp. 706-712 ◽

Cited By ~ 9

Author(s):

Anujith Kumar ◽

Dipankar Nandi

Keyword(s):

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Serovar Typhimurium

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Role of SPI-1 Secreted Effectors in Acute Bovine Response to Salmonella enterica Serovar Typhimurium: A Systems Biology Analysis Approach

PLoS ONE ◽

10.1371/journal.pone.0026869 ◽

2011 ◽

Vol 6 (11) ◽

pp. e26869 ◽

Cited By ~ 29

Author(s):

Sara D. Lawhon ◽

Sangeeta Khare ◽

Carlos A. Rossetti ◽

Robin E. Everts ◽

Cristi L. Galindo ◽

...

Keyword(s):

Systems Biology ◽

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Analysis Approach ◽

Serovar Typhimurium

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Arginine-Dependent Acid Resistance in Salmonella enterica Serovar Typhimurium

Journal of Bacteriology ◽

10.1128/jb.00323-06 ◽

2006 ◽

Vol 188 (15) ◽

pp. 5650-5653 ◽

Cited By ~ 59

Author(s):

Jasper Kieboom ◽

Tjakko Abee

Keyword(s):

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Acid Resistance ◽

Arginine Decarboxylase ◽

Acidic Ph ◽

E Coli ◽

Serovar Typhimurium ◽

Microaerobic Conditions ◽

Acid Challenge

ABSTRACT Salmonella enterica serovar Typhimurium does not survive a pH 2.5 acid challenge under conditions similar to those used for Escherichia coli (J. W. Foster, Nat. Rev. Microbiol. 2:898-907, 2004). Here, we provide evidence that S. enterica serovar Typhimurium can display arginine-dependent acid resistance (AR) provided the cells are grown under anoxic conditions and not under the microaerobic conditions used for assessment of AR in E. coli. The role of the arginine decarboxylase pathway in Salmonella AR was shown by the loss of AR in mutants lacking adiA, which encodes arginine decarboxylase; adiC, which encodes the arginine-agmatine antiporter; or adiY, which encodes an AraC-like regulator. Transcription of adiA and adiC was found to be dependent on AdiY, anaerobiosis, and acidic pH.

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Influence of Temperature and Predation on Survival of Salmonella enterica Serovar Typhimurium and Expression of invA in Soil and Manure-Amended Soil

Applied and Environmental Microbiology ◽

10.1128/aem.00628-10 ◽

2010 ◽

Vol 76 (15) ◽

pp. 5025-5031 ◽

Cited By ~ 53

Author(s):

R. GarcÃ¯Â¿Â½a ◽

J. BÃ¯Â¿Â½lum ◽

L. Fredslund ◽

P. Santorum ◽

C. S. Jacobsen

Keyword(s):

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Mrna Levels ◽

Predator Prey ◽

Fast Decrease ◽

Serovar Typhimurium ◽

Prey Interaction ◽

Rna And Dna ◽

Amended Soil

ABSTRACT The effects of three temperatures (5, 15, and 25Ã¯Â¿Â½C) on the survival of Salmonella enterica serovar Typhimurium in topsoil were investigated in small microcosms by three different techniques: plate counting, invA gene quantification, and invA mRNA quantification. Differences in survival were related to the effect of protozoan predation. Tetracycline-resistant Salmonella serovar Typhimurium was inoculated into soil and manure-amended soil at 1.5 Ã¯Â¿Â½ 108 cells g soil−1. Population densities were determined by plate counting and by molecular methods and monitored for 42 days. Simultaneous extraction of RNA and DNA, followed by quantitative PCR, was used to investigate invA gene levels and expression. Analysis by these three techniques showed that Salmonella serovar Typhimurium survived better at 5Ã¯Â¿Â½C. Comparing DNA and CFU levels, significantly higher values were determined by DNA-based techniques. invA mRNA levels showed a fast decrease in activity, with no detectable mRNA after an incubation period of less than 4 days in any of the soil scenarios. A negative correlation was found between Salmonella serovar Typhimurium CFU levels and protozoan most probable numbers, and we propose the role of the predator-prey interaction as a factor to explain the die-off of the introduced strain by both culture- and DNA quantification-based methods. The results indicate that temperature, manure, and protozoan predation are important factors influencing the survival of Salmonella serovar Typhimurium in soil.

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Role of the High-Affinity Zinc Uptake znuABC System in Salmonella enterica Serovar Typhimurium Virulence

Infection and Immunity ◽

10.1128/iai.70.8.4721-4725.2002 ◽

2002 ◽

Vol 70 (8) ◽

pp. 4721-4725 ◽

Cited By ~ 97

Author(s):

Susana Campoy ◽

Mónica Jara ◽

Núria Busquets ◽

Ana M. Pérez de Rozas ◽

Ignacio Badiola ◽

...

Keyword(s):

Salmonella Enterica ◽

Salmonella Enterica Serovar Typhimurium ◽

Lethal Dose ◽

Zinc Uptake ◽

Uptake System ◽

High Affinity ◽

Knockout Mutants ◽

Serovar Typhimurium ◽

Genes Encoding

ABSTRACT The Salmonella enterica serovar Typhimurium znuABC genes encoding a high-affinity zinc uptake system and its regulatory zur gene have been cloned. Salmonella serovar Typhimurium zur and znuC knockout mutants have been constructed by marker exchange. The 50% lethal dose of the znuC mutant increased when either orally or intraperitoneally inoculated in BALB/c mice, while virulence of the zur mutant decreased only when mice were intraperitoneally challenged.

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