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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

Percentage survival in G. mellonella 24h post-infection in different strains.
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pone.0135010.g004: Percentage survival in G. mellonella 24h post-infection in different strains.

Mentions: To further assess the virulence potential of S. Typhimurium Sal199 and S. Infantis Sal147 strains, in vivo assays were performed using the larvae of the Greater wax moth G. mellonella. The mean rate of survival of Galleria at this bacterial dose was strain and growth time dependent. Sal147 strain, grown for 24h, showed a higher percentage of survival, at an average of 50% (range 40–60%) than S. Typhimurium Sal199 that presented a mean survival of 10% (range 0–20%). S. Typhimurium LT2 and S. Infantis Sal280 presented a survival rate of 16.7% (range 10–20%) (Fig 4). Therefore, the mean rate of survival for Sal147 infected larvae was up to 3 times higher when compared to Sal280; while the mortality rate of Sal199 infected larvae was 1.6 times higher compared to LT2. A colour change was observed in some larvae following 24 h incubation. Those killed following infection were black or dark brown while surviving larvae were white and looked identical to the uninfected and PBS controls.


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)

Percentage survival in G. mellonella 24h post-infection in different strains.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0135010.g004: Percentage survival in G. mellonella 24h post-infection in different strains.
Mentions: To further assess the virulence potential of S. Typhimurium Sal199 and S. Infantis Sal147 strains, in vivo assays were performed using the larvae of the Greater wax moth G. mellonella. The mean rate of survival of Galleria at this bacterial dose was strain and growth time dependent. Sal147 strain, grown for 24h, showed a higher percentage of survival, at an average of 50% (range 40–60%) than S. Typhimurium Sal199 that presented a mean survival of 10% (range 0–20%). S. Typhimurium LT2 and S. Infantis Sal280 presented a survival rate of 16.7% (range 10–20%) (Fig 4). Therefore, the mean rate of survival for Sal147 infected larvae was up to 3 times higher when compared to Sal280; while the mortality rate of Sal199 infected larvae was 1.6 times higher compared to LT2. A colour change was observed in some larvae following 24 h incubation. Those killed following infection were black or dark brown while surviving larvae were white and looked identical to the uninfected and PBS controls.

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