PMID:25461694

Citation	Gao, Q, Ye, Z, Wang, X, Mu, X, Gao, S and Liu, X (2015) RstA is required for the virulence of an avian pathogenic Escherichia coli O2 strain E058. Infect. Genet. Evol. 29:180-8
Abstract	Certain strains of avian pathogenic Escherichia coli (APEC) cause severe extraintestinal infections in poultry, including acute fatal septicemia, subacute pericarditis, and airsacculitis. These bacteria contain an RstA/RstB regulatory system, a two-component system that may help APEC strains adapt to the extra-intestinal environment and survive under stressful conditions. Whether RstA correlates with APEC pathogenesis or acts as an APEC virulence factor has not been established. Here we provide the first evidence for an important role of rstA in APEC virulence. We generated an rstA-deficient mutant from the highly virulent APEC strain E058. Virulence of the mutant strain was evaluated in vivo and in vitro through bird infection assays, a cytotoxicity assay on chicken macrophage cell line HD-11, and a bactericidal assay to serum complement. Based on lethality assays in 1-day-old birds, rstA deletion from APEC E058 reduced the bacterial virulence in birds. The deletion also deeply impaired the capacity of APEC E058 to colonize deeper tissues of 5-week-old specific pathogen free chickens. No obvious gross or histopathological lesions were observed in the visceral organs of chickens challenged with the rstA-deficient strain. Also, rstA inactivation reduced the survival of APEC E058 within chicken macrophages. However, no significant differences were observed between the mutant and the wild-type strain in resistance to serum. Our data collectively show that the rstA gene functions in the pathogenesis of diseases caused by avian pathogenic E. coli.
Links	PubMed Online version:10.1016/j.meegid.2014.11.022
Keywords	Animals; Chickens/microbiology; Escherichia coli/genetics; Escherichia coli/pathogenicity; Escherichia coli Infections/microbiology; Escherichia coli Infections/pathology; Escherichia coli Infections/veterinary; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Heart/virology; INDEL Mutation; Liver/virology; Lung/virology; Poultry Diseases/microbiology; Poultry Diseases/pathology; Virulence Factors/genetics; Virulence Factors/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLX:A0A152UJI2		GO:0009405: pathogenesis	ECO:0000315:		P		Fig. 4 Colonization of the Escherichia coli (E058 strain) ∆rstA mutant was significant lower than those of the wild-type E058 strain in the internal organs of chickens.	complete CACAO 12376

References

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