Inactivation of the Pst System Reduces the Virulence of an Avian Pathogenic Escherichia coli O78 Strain
| Autor: | Martin G. Lamarche, Charles M. Dozois, France Daigle, Mélissa Caza, Roy Curtiss, J. Daniel Dubreuil, Josée Harel |
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| Rok vydání: | 2005 |
| Předmět: |
Blood Bactericidal Activity
Operon Immunology Mutant Virulence Biology medicine.disease_cause Microbiology Phosphates Bacterial Proteins Pathogenic Escherichia coli Escherichia coli medicine Animals Polymyxins Adenosine Triphosphatases Strain (chemistry) Escherichia coli Proteins fungi food and beverages Phosphate-Binding Proteins biology.organism_classification Molecular Pathogenesis Enterobacteriaceae Infectious Diseases Regulon Periplasmic Binding Proteins ATP-Binding Cassette Transporters Parasitology Chickens |
| Zdroj: | Infection and Immunity. 73:4138-4145 |
| ISSN: | 1098-5522 0019-9567 |
| DOI: | 10.1128/iai.73.7.4138-4145.2005 |
| Popis: | Escherichia coli O78 strains are frequently associated with extraintestinal diseases, such as airsacculitis and septicemia, in poultry, livestock, and humans. To understand the influence of the pst operon in the virulence of E. coli , we introduced mutations into the pst genes of the avian pathogenic E. coli (APEC) O78:K80 strain χ7122 by allelic exchange. The mutation of pst genes led to the constitutive expression of the Pho regulon. Furthermore, the virulence of APEC strain χ7122 in a chicken infection model was attenuated by inactivation of the Pst system. The pst mutant caused significantly fewer extraintestinal lesions in infected chickens, and bacterial numbers isolated from different tissues after infection were significantly lower for the mutant than for the wild-type strain. Moreover, resistance to the bactericidal effects of rabbit serum and acid shock was impaired in the pst mutant, in contrast to the wild-type strain. In addition, the MIC of polymyxin was twofold lower for the mutant than for the wild-type strain. Although the pst mutant demonstrated an increased susceptibility to rabbit serum, this strain was not killed by chicken serum, suggesting the presence of differences in host innate immune defenses and complement-mediated killing. In APEC O78 strain χ7122, a functional Pst system is required for full virulence and resistance to acid shock and polymyxin. Our results suggest that the mutation of pst genes induces a deregulation of phosphate sensing and changes in the cell surface composition that lead to decreased virulence, indicating the importance of the Pst system for the virulence of pathogenic E. coli strains from different hosts. |
| Databáze: | OpenAIRE |
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