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Virulence Characterization of Salmonella enterica by a New Microarray: Detection and Evaluation of the Cytolethal Distending Toxin Gene Activity in the Unusual Host S. Typhimurium.

Figueiredo R, Card R, Nunes C, AbuOun M, Bagnall MC, Nunez J, Mendonça N, Anjum MF, da Silva GJ - PLoS ONE (2015)

Bottom Line: Increased mortality of Galleria was detected on infection with Sal199 compared to LT2.This work demonstrates that the use of suitable screening methods for Salmonella virulence can help assess the potential risk associated with certain Salmonella to humans.Incorporation of such methodology into surveillance could help reduce the risk of emergence of epidemic Salmonella strains.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Pharmacy and Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.

ABSTRACT
Salmonella enterica is a zoonotic foodborne pathogen that causes acute gastroenteritis in humans. We assessed the virulence potential of one-hundred and six Salmonella strains isolated from food animals and products. A high through-put virulence genes microarray demonstrated Salmonella Pathogenicity Islands (SPI) and adherence genes were highly conserved, while prophages and virulence plasmid genes were variably present. Isolates were grouped by serotype, and virulence plasmids separated S. Typhimurium in two clusters. Atypical microarray results lead to whole genome sequencing (WGS) of S. Infantis Sal147, which identified deletion of thirty-eight SPI-1 genes. Sal147 was unable to invade HeLa cells and showed reduced mortality in Galleria mellonella infection model, in comparison to a SPI-1 harbouring S. Infantis. Microarray and WGS of S. Typhimurium Sal199, established for the first time in S. Typhimurium presence of cdtB and other Typhi-related genes. Characterization of Sal199 showed cdtB genes were upstream of transposase IS911, and co-expressed with other Typhi-related genes. Cell cycle arrest, cytoplasmic distension, and nuclear enlargement were detected in HeLa cells infected by Sal199, but not with S. Typhimurium LT2. Increased mortality of Galleria was detected on infection with Sal199 compared to LT2. Thus, Salmonella isolates were rapidly characterized using a high through-put microarray; helping to identify unusual virulence features which were corroborated by further characterisation. This work demonstrates that the use of suitable screening methods for Salmonella virulence can help assess the potential risk associated with certain Salmonella to humans. Incorporation of such methodology into surveillance could help reduce the risk of emergence of epidemic Salmonella strains.

No MeSH data available.


Related in: MedlinePlus

(A) Effect of the CdtB toxin in HeLa cells, 72h after S. Typhimurium Sal199 infection. On top, untreated HeLa cells, in middle, HeLa cells infected with S. Typhimurium LT2, and on bottom, HeLa cells infected with S. Typhimurium Sal199. The cells were examined at same magnification (40x) by light microscope, and the cell cycle arrest measured by flow cytometry. The peaks corresponding to cells in G1, S and G2/M are indicated. (B) Ratio G0/G1/G2/M of cell cycle profiles from at least three independent experiments.
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pone.0135010.g002: (A) Effect of the CdtB toxin in HeLa cells, 72h after S. Typhimurium Sal199 infection. On top, untreated HeLa cells, in middle, HeLa cells infected with S. Typhimurium LT2, and on bottom, HeLa cells infected with S. Typhimurium Sal199. The cells were examined at same magnification (40x) by light microscope, and the cell cycle arrest measured by flow cytometry. The peaks corresponding to cells in G1, S and G2/M are indicated. (B) Ratio G0/G1/G2/M of cell cycle profiles from at least three independent experiments.

Mentions: Cytolethal distending intracellular tripartite toxin causes cell arrest in G2 / M transition phase, and consequently a nucleus enlargement and an increase in the amount of DNA can be observed in eukaryotic cells. S. Typhimurium Sal199 was examined using flow cytometry for its ability to block cell cycle arrest by analysing the DNA content of HeLa cells. HeLa cells infected with S. Typhimurium LT2 were essentially identical to the control (no infected cells), with a large accumulation of cells in the G0 / G1. In contrast, HeLa cells infected with Sal199 become arrested in G2 / M phase after 72 h in comparison to un-infected cells (Fig 2A). The ratio G0 / G1 to G2 / M of cell cycle profiles is shown in Fig 2B. The results from profiles of the DNA content suggest that S. Typhimurium Sal199 exhibited G2 / M arrest.


Virulence Characterization of Salmonella enterica by a New Microarray: Detection and Evaluation of the Cytolethal Distending Toxin Gene Activity in the Unusual Host S. Typhimurium.

Figueiredo R, Card R, Nunes C, AbuOun M, Bagnall MC, Nunez J, Mendonça N, Anjum MF, da Silva GJ - PLoS ONE (2015)

(A) Effect of the CdtB toxin in HeLa cells, 72h after S. Typhimurium Sal199 infection. On top, untreated HeLa cells, in middle, HeLa cells infected with S. Typhimurium LT2, and on bottom, HeLa cells infected with S. Typhimurium Sal199. The cells were examined at same magnification (40x) by light microscope, and the cell cycle arrest measured by flow cytometry. The peaks corresponding to cells in G1, S and G2/M are indicated. (B) Ratio G0/G1/G2/M of cell cycle profiles from at least three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4526557&req=5

pone.0135010.g002: (A) Effect of the CdtB toxin in HeLa cells, 72h after S. Typhimurium Sal199 infection. On top, untreated HeLa cells, in middle, HeLa cells infected with S. Typhimurium LT2, and on bottom, HeLa cells infected with S. Typhimurium Sal199. The cells were examined at same magnification (40x) by light microscope, and the cell cycle arrest measured by flow cytometry. The peaks corresponding to cells in G1, S and G2/M are indicated. (B) Ratio G0/G1/G2/M of cell cycle profiles from at least three independent experiments.
Mentions: Cytolethal distending intracellular tripartite toxin causes cell arrest in G2 / M transition phase, and consequently a nucleus enlargement and an increase in the amount of DNA can be observed in eukaryotic cells. S. Typhimurium Sal199 was examined using flow cytometry for its ability to block cell cycle arrest by analysing the DNA content of HeLa cells. HeLa cells infected with S. Typhimurium LT2 were essentially identical to the control (no infected cells), with a large accumulation of cells in the G0 / G1. In contrast, HeLa cells infected with Sal199 become arrested in G2 / M phase after 72 h in comparison to un-infected cells (Fig 2A). The ratio G0 / G1 to G2 / M of cell cycle profiles is shown in Fig 2B. The results from profiles of the DNA content suggest that S. Typhimurium Sal199 exhibited G2 / M arrest.

Bottom Line: Increased mortality of Galleria was detected on infection with Sal199 compared to LT2.This work demonstrates that the use of suitable screening methods for Salmonella virulence can help assess the potential risk associated with certain Salmonella to humans.Incorporation of such methodology into surveillance could help reduce the risk of emergence of epidemic Salmonella strains.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Pharmacy and Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Department of Bacteriology, Animal and Plant Health Agency, Weybridge, New Haw, Addlestone, Surrey, KT15 3NB, United Kingdom.

ABSTRACT
Salmonella enterica is a zoonotic foodborne pathogen that causes acute gastroenteritis in humans. We assessed the virulence potential of one-hundred and six Salmonella strains isolated from food animals and products. A high through-put virulence genes microarray demonstrated Salmonella Pathogenicity Islands (SPI) and adherence genes were highly conserved, while prophages and virulence plasmid genes were variably present. Isolates were grouped by serotype, and virulence plasmids separated S. Typhimurium in two clusters. Atypical microarray results lead to whole genome sequencing (WGS) of S. Infantis Sal147, which identified deletion of thirty-eight SPI-1 genes. Sal147 was unable to invade HeLa cells and showed reduced mortality in Galleria mellonella infection model, in comparison to a SPI-1 harbouring S. Infantis. Microarray and WGS of S. Typhimurium Sal199, established for the first time in S. Typhimurium presence of cdtB and other Typhi-related genes. Characterization of Sal199 showed cdtB genes were upstream of transposase IS911, and co-expressed with other Typhi-related genes. Cell cycle arrest, cytoplasmic distension, and nuclear enlargement were detected in HeLa cells infected by Sal199, but not with S. Typhimurium LT2. Increased mortality of Galleria was detected on infection with Sal199 compared to LT2. Thus, Salmonella isolates were rapidly characterized using a high through-put microarray; helping to identify unusual virulence features which were corroborated by further characterisation. This work demonstrates that the use of suitable screening methods for Salmonella virulence can help assess the potential risk associated with certain Salmonella to humans. Incorporation of such methodology into surveillance could help reduce the risk of emergence of epidemic Salmonella strains.

No MeSH data available.


Related in: MedlinePlus