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IbeR facilitates stress-resistance, invasion and pathogenicity of avian pathogenic Escherichia coli.

Wang S, Bao Y, Meng Q, Xia Y, Zhao Y, Wang Y, Tang F, ZhuGe X, Yu S, Han X, Dai J, Lu C - PLoS ONE (2015)

Bottom Line: Inactivation of ibeR led to attenuated virulence and reduced invasion capacity towards DF-1 cells, brains and cerebrospinal fluid (CSF) in vitro and in vivo.These virulence-related phenotypes were restored by genetic complementation.Quantitative real-time reverse transcription PCR revealed that IbeR controlled expression of stress-resistance genes and virulence genes, which might led to the associated virulence phenotype.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.

ABSTRACT
Systemic infections by avian pathogenic Escherichia coli (APEC) are economically devastating to poultry industries worldwide. IbeR, located on genomic island GimA, was shown to serve as an RpoS-like regulator in rpoS gene mutation neonatal meningitis E. coli (NMEC) RS218. However, the role of IbeR in pathogenicity of APEC carrying active RpoS has not yet been investigated. We showed that the APEC IbeR could elicit antibodies in infected ducks, suggesting that IbeR might be involved in APEC pathogenicity. To investigate the function of IbeR in APEC pathogenesis, mutant and complementation strains were constructed and characterized. Inactivation of ibeR led to attenuated virulence and reduced invasion capacity towards DF-1 cells, brains and cerebrospinal fluid (CSF) in vitro and in vivo. Bactericidal assays demonstrated that the mutant strain had impaired resistance to environmental stress and specific pathogen-free (SPF) chicken serum. These virulence-related phenotypes were restored by genetic complementation. Quantitative real-time reverse transcription PCR revealed that IbeR controlled expression of stress-resistance genes and virulence genes, which might led to the associated virulence phenotype.

No MeSH data available.


Related in: MedlinePlus

Animal infection experiments.(A) Bacterial enumeration during animal systemic infection. Groups of six 8-week-old ICR mice were infected intraperitoneally with a sublethal dose bacterial suspension of 2.0 × 106 CFUs. Bacteria were recovered from blood, brains, lungs, liver and spleen at 24 h post infection. (B) Bacterial enumeration in rat neonatal meningitis model. At 5 days of age, groups of five SPF Sprague-Dawley rat pups were inoculated intraperitoneally with a bacterial suspension containing 107 CFUs. At 18 h after bacterial inoculation, blood and cerebrospinal fluid (CSF) specimens were obtained for quantitative cultures. Nonparametric Mann-Whitney U-Test was carried out for statistical significance analysis. * p < 0.05.
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pone.0119698.g005: Animal infection experiments.(A) Bacterial enumeration during animal systemic infection. Groups of six 8-week-old ICR mice were infected intraperitoneally with a sublethal dose bacterial suspension of 2.0 × 106 CFUs. Bacteria were recovered from blood, brains, lungs, liver and spleen at 24 h post infection. (B) Bacterial enumeration in rat neonatal meningitis model. At 5 days of age, groups of five SPF Sprague-Dawley rat pups were inoculated intraperitoneally with a bacterial suspension containing 107 CFUs. At 18 h after bacterial inoculation, blood and cerebrospinal fluid (CSF) specimens were obtained for quantitative cultures. Nonparametric Mann-Whitney U-Test was carried out for statistical significance analysis. * p < 0.05.

Mentions: To determine the effect of IbeR in vivo, systemic infection experiments were performed. Bacteria were recovered from blood, brains, lungs, livers and spleens of infected mice at 24 h post inoculation. Recovered ΔibeR compared to wild-type strain DE205B was reduced 1.6-fold in blood, 7.7-fold in brain, 3.4-fold in lung, 4.7-fold in liver, and 1.1-fold in spleen (Fig. 5A). Colonization and invasion capacities in brain and liver were significantly decreased (p < 0.05). Recovered complementation strains in organs were restored with differences between strains DE205B and CΔibeR that were not significant (p > 0.05). Furthermore, the complementation strain CΔibeR showed significantly increased invasion capacity in brain compared to the mutant strain ΔibeR (p < 0.05). These results indicated that IbeR was involved in invasion of the brain of APEC strain DE205B during systemic infection.


IbeR facilitates stress-resistance, invasion and pathogenicity of avian pathogenic Escherichia coli.

Wang S, Bao Y, Meng Q, Xia Y, Zhao Y, Wang Y, Tang F, ZhuGe X, Yu S, Han X, Dai J, Lu C - PLoS ONE (2015)

Animal infection experiments.(A) Bacterial enumeration during animal systemic infection. Groups of six 8-week-old ICR mice were infected intraperitoneally with a sublethal dose bacterial suspension of 2.0 × 106 CFUs. Bacteria were recovered from blood, brains, lungs, liver and spleen at 24 h post infection. (B) Bacterial enumeration in rat neonatal meningitis model. At 5 days of age, groups of five SPF Sprague-Dawley rat pups were inoculated intraperitoneally with a bacterial suspension containing 107 CFUs. At 18 h after bacterial inoculation, blood and cerebrospinal fluid (CSF) specimens were obtained for quantitative cultures. Nonparametric Mann-Whitney U-Test was carried out for statistical significance analysis. * p < 0.05.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4359115&req=5

pone.0119698.g005: Animal infection experiments.(A) Bacterial enumeration during animal systemic infection. Groups of six 8-week-old ICR mice were infected intraperitoneally with a sublethal dose bacterial suspension of 2.0 × 106 CFUs. Bacteria were recovered from blood, brains, lungs, liver and spleen at 24 h post infection. (B) Bacterial enumeration in rat neonatal meningitis model. At 5 days of age, groups of five SPF Sprague-Dawley rat pups were inoculated intraperitoneally with a bacterial suspension containing 107 CFUs. At 18 h after bacterial inoculation, blood and cerebrospinal fluid (CSF) specimens were obtained for quantitative cultures. Nonparametric Mann-Whitney U-Test was carried out for statistical significance analysis. * p < 0.05.
Mentions: To determine the effect of IbeR in vivo, systemic infection experiments were performed. Bacteria were recovered from blood, brains, lungs, livers and spleens of infected mice at 24 h post inoculation. Recovered ΔibeR compared to wild-type strain DE205B was reduced 1.6-fold in blood, 7.7-fold in brain, 3.4-fold in lung, 4.7-fold in liver, and 1.1-fold in spleen (Fig. 5A). Colonization and invasion capacities in brain and liver were significantly decreased (p < 0.05). Recovered complementation strains in organs were restored with differences between strains DE205B and CΔibeR that were not significant (p > 0.05). Furthermore, the complementation strain CΔibeR showed significantly increased invasion capacity in brain compared to the mutant strain ΔibeR (p < 0.05). These results indicated that IbeR was involved in invasion of the brain of APEC strain DE205B during systemic infection.

Bottom Line: Inactivation of ibeR led to attenuated virulence and reduced invasion capacity towards DF-1 cells, brains and cerebrospinal fluid (CSF) in vitro and in vivo.These virulence-related phenotypes were restored by genetic complementation.Quantitative real-time reverse transcription PCR revealed that IbeR controlled expression of stress-resistance genes and virulence genes, which might led to the associated virulence phenotype.

View Article: PubMed Central - PubMed

Affiliation: Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.

ABSTRACT
Systemic infections by avian pathogenic Escherichia coli (APEC) are economically devastating to poultry industries worldwide. IbeR, located on genomic island GimA, was shown to serve as an RpoS-like regulator in rpoS gene mutation neonatal meningitis E. coli (NMEC) RS218. However, the role of IbeR in pathogenicity of APEC carrying active RpoS has not yet been investigated. We showed that the APEC IbeR could elicit antibodies in infected ducks, suggesting that IbeR might be involved in APEC pathogenicity. To investigate the function of IbeR in APEC pathogenesis, mutant and complementation strains were constructed and characterized. Inactivation of ibeR led to attenuated virulence and reduced invasion capacity towards DF-1 cells, brains and cerebrospinal fluid (CSF) in vitro and in vivo. Bactericidal assays demonstrated that the mutant strain had impaired resistance to environmental stress and specific pathogen-free (SPF) chicken serum. These virulence-related phenotypes were restored by genetic complementation. Quantitative real-time reverse transcription PCR revealed that IbeR controlled expression of stress-resistance genes and virulence genes, which might led to the associated virulence phenotype.

No MeSH data available.


Related in: MedlinePlus