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Contribution of the type VI secretion system encoded in SPI-19 to chicken colonization by Salmonella enterica serotypes Gallinarum and Enteritidis.

Blondel CJ, Yang HJ, Castro B, Chiang S, Toro CS, Zaldívar M, Contreras I, Andrews-Polymenis HL, Santiviago CA - PLoS ONE (2010)

Bottom Line: Non-polar deletion mutants of SPI-19 and the clpV gene, an essential T6SS component, colonized the ileum, ceca, liver and spleen of White Leghorn chicks poorly compared to the wild-type strain after oral inoculation.In contrast, transfer of SPI-19 from Gallinarum to Enteritidis resulted in transient increase in the colonization of the ileum, liver and spleen at day 1 post-infection, but at days 3 and 5 post-infection a strong colonization defect of the gut and internal organs of the experimentally infected chickens was observed.Our data indicate that SPI-19 and the T6SS encoded in this region contribute to the colonization of the gastrointestinal tract and internal organs of chickens by Salmonella Gallinarum and suggest that degradation of SPI-19 T6SS in Salmonella Enteritidis conferred an advantage in colonization of the avian host.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.

ABSTRACT
Salmonella Gallinarum is a pathogen with a host range specific to poultry, while Salmonella Enteritidis is a broad host range pathogen that colonizes poultry sub-clinically but is a leading cause of gastrointestinal salmonellosis in humans and many other species. Despite recent advances in our understanding of the complex interplay between Salmonella and their hosts, the molecular basis of host range restriction and unique pathobiology of Gallinarum remain largely unknown. Type VI Secretion System (T6SS) represents a new paradigm of protein secretion that is critical for the pathogenesis of many gram-negative bacteria. We recently identified a putative T6SS in the Salmonella Pathogenicity Island 19 (SPI-19) of Gallinarum. In Enteritidis, SPI-19 is a degenerate element that has lost most of the T6SS functions encoded in the island. In this work, we studied the contribution of SPI-19 to the colonization of Salmonella Gallinarum strain 287/91 in chickens. Non-polar deletion mutants of SPI-19 and the clpV gene, an essential T6SS component, colonized the ileum, ceca, liver and spleen of White Leghorn chicks poorly compared to the wild-type strain after oral inoculation. Return of SPI-19 to the DeltaSPI-19 mutant, using VEX-Capture, complemented this colonization defect. In contrast, transfer of SPI-19 from Gallinarum to Enteritidis resulted in transient increase in the colonization of the ileum, liver and spleen at day 1 post-infection, but at days 3 and 5 post-infection a strong colonization defect of the gut and internal organs of the experimentally infected chickens was observed. Our data indicate that SPI-19 and the T6SS encoded in this region contribute to the colonization of the gastrointestinal tract and internal organs of chickens by Salmonella Gallinarum and suggest that degradation of SPI-19 T6SS in Salmonella Enteritidis conferred an advantage in colonization of the avian host.

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Competitive index experiments with ΔSPI-19 and ΔclpV mutants versus the wild-type S. Gallinarum strain 287/91.Four day old White Leghorn chicks were orally infected with ∼109 CFU of an approximately equal mixture of the mutant strains and the wild-type Gallinarum 287/91 strain. After 1, 3 and 5 days post-infection the chicks were humanely euthanized, the ileum, ceca, liver and spleen were recovered. Tissues were homogenized and viable counts were determined after serial dilution of the homogenates and plating on appropriate media. Error bars represent standard error. Statistical significance was determined using a two-tailed Student's t test. Asterisks indicate that normalized output ratios were significantly statistically different from the equivalent ratio in the inoculum. ** P value of <0.001, * P value of <0.05.
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pone-0011724-g003: Competitive index experiments with ΔSPI-19 and ΔclpV mutants versus the wild-type S. Gallinarum strain 287/91.Four day old White Leghorn chicks were orally infected with ∼109 CFU of an approximately equal mixture of the mutant strains and the wild-type Gallinarum 287/91 strain. After 1, 3 and 5 days post-infection the chicks were humanely euthanized, the ileum, ceca, liver and spleen were recovered. Tissues were homogenized and viable counts were determined after serial dilution of the homogenates and plating on appropriate media. Error bars represent standard error. Statistical significance was determined using a two-tailed Student's t test. Asterisks indicate that normalized output ratios were significantly statistically different from the equivalent ratio in the inoculum. ** P value of <0.001, * P value of <0.05.

Mentions: To evaluate the role played by SPI-19 in the colonization of chickens by S. Gallinarum, a ΔSPI-19 derivative of strain 287/91 was constructed and tested in a competitive index experiment. White Leghorn chicks were orally infected with ∼109 CFU of a 1∶1 mixture of the mutant and the parental wild-type strain at four days post-hatch. Birds were euthanized at 1, 3, and 5 days post infection, bacteria were recovered from the ileum, ceca, liver and spleen of infected birds and the ability of the mutant to compete for organ colonization against the wild-type parental isolate was evaluated (Figure 3). The ΔSPI-19 mutant had a deficit in colonization of the intestine immediately after infection that became more severe throughout the duration of the experiment. ΔSPI-19 mutants also had reduced colonization of systemic organs, including the liver and spleen, of chicks at all time points post-infection.


Contribution of the type VI secretion system encoded in SPI-19 to chicken colonization by Salmonella enterica serotypes Gallinarum and Enteritidis.

Blondel CJ, Yang HJ, Castro B, Chiang S, Toro CS, Zaldívar M, Contreras I, Andrews-Polymenis HL, Santiviago CA - PLoS ONE (2010)

Competitive index experiments with ΔSPI-19 and ΔclpV mutants versus the wild-type S. Gallinarum strain 287/91.Four day old White Leghorn chicks were orally infected with ∼109 CFU of an approximately equal mixture of the mutant strains and the wild-type Gallinarum 287/91 strain. After 1, 3 and 5 days post-infection the chicks were humanely euthanized, the ileum, ceca, liver and spleen were recovered. Tissues were homogenized and viable counts were determined after serial dilution of the homogenates and plating on appropriate media. Error bars represent standard error. Statistical significance was determined using a two-tailed Student's t test. Asterisks indicate that normalized output ratios were significantly statistically different from the equivalent ratio in the inoculum. ** P value of <0.001, * P value of <0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908676&req=5

pone-0011724-g003: Competitive index experiments with ΔSPI-19 and ΔclpV mutants versus the wild-type S. Gallinarum strain 287/91.Four day old White Leghorn chicks were orally infected with ∼109 CFU of an approximately equal mixture of the mutant strains and the wild-type Gallinarum 287/91 strain. After 1, 3 and 5 days post-infection the chicks were humanely euthanized, the ileum, ceca, liver and spleen were recovered. Tissues were homogenized and viable counts were determined after serial dilution of the homogenates and plating on appropriate media. Error bars represent standard error. Statistical significance was determined using a two-tailed Student's t test. Asterisks indicate that normalized output ratios were significantly statistically different from the equivalent ratio in the inoculum. ** P value of <0.001, * P value of <0.05.
Mentions: To evaluate the role played by SPI-19 in the colonization of chickens by S. Gallinarum, a ΔSPI-19 derivative of strain 287/91 was constructed and tested in a competitive index experiment. White Leghorn chicks were orally infected with ∼109 CFU of a 1∶1 mixture of the mutant and the parental wild-type strain at four days post-hatch. Birds were euthanized at 1, 3, and 5 days post infection, bacteria were recovered from the ileum, ceca, liver and spleen of infected birds and the ability of the mutant to compete for organ colonization against the wild-type parental isolate was evaluated (Figure 3). The ΔSPI-19 mutant had a deficit in colonization of the intestine immediately after infection that became more severe throughout the duration of the experiment. ΔSPI-19 mutants also had reduced colonization of systemic organs, including the liver and spleen, of chicks at all time points post-infection.

Bottom Line: Non-polar deletion mutants of SPI-19 and the clpV gene, an essential T6SS component, colonized the ileum, ceca, liver and spleen of White Leghorn chicks poorly compared to the wild-type strain after oral inoculation.In contrast, transfer of SPI-19 from Gallinarum to Enteritidis resulted in transient increase in the colonization of the ileum, liver and spleen at day 1 post-infection, but at days 3 and 5 post-infection a strong colonization defect of the gut and internal organs of the experimentally infected chickens was observed.Our data indicate that SPI-19 and the T6SS encoded in this region contribute to the colonization of the gastrointestinal tract and internal organs of chickens by Salmonella Gallinarum and suggest that degradation of SPI-19 T6SS in Salmonella Enteritidis conferred an advantage in colonization of the avian host.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.

ABSTRACT
Salmonella Gallinarum is a pathogen with a host range specific to poultry, while Salmonella Enteritidis is a broad host range pathogen that colonizes poultry sub-clinically but is a leading cause of gastrointestinal salmonellosis in humans and many other species. Despite recent advances in our understanding of the complex interplay between Salmonella and their hosts, the molecular basis of host range restriction and unique pathobiology of Gallinarum remain largely unknown. Type VI Secretion System (T6SS) represents a new paradigm of protein secretion that is critical for the pathogenesis of many gram-negative bacteria. We recently identified a putative T6SS in the Salmonella Pathogenicity Island 19 (SPI-19) of Gallinarum. In Enteritidis, SPI-19 is a degenerate element that has lost most of the T6SS functions encoded in the island. In this work, we studied the contribution of SPI-19 to the colonization of Salmonella Gallinarum strain 287/91 in chickens. Non-polar deletion mutants of SPI-19 and the clpV gene, an essential T6SS component, colonized the ileum, ceca, liver and spleen of White Leghorn chicks poorly compared to the wild-type strain after oral inoculation. Return of SPI-19 to the DeltaSPI-19 mutant, using VEX-Capture, complemented this colonization defect. In contrast, transfer of SPI-19 from Gallinarum to Enteritidis resulted in transient increase in the colonization of the ileum, liver and spleen at day 1 post-infection, but at days 3 and 5 post-infection a strong colonization defect of the gut and internal organs of the experimentally infected chickens was observed. Our data indicate that SPI-19 and the T6SS encoded in this region contribute to the colonization of the gastrointestinal tract and internal organs of chickens by Salmonella Gallinarum and suggest that degradation of SPI-19 T6SS in Salmonella Enteritidis conferred an advantage in colonization of the avian host.

Show MeSH
Related in: MedlinePlus