title: RstA is required for the virulence of an avian pathogenic Escherichia coli O2 strain E058.
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.
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Gao
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
authors.forename: Zhengqin
authors.initials: Z
authors.lastname: Ye
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Wang
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Mu
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China. Electronic address: gsong@yzu.edu.cn.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.affiliation: Animal Infectious Disease Laboratory, Ministry of Agriculture, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, PR China.
authors.forename: Xiufan
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D002645:Chickens / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006321:Heart / Q000821:virology; D054643:INDEL Mutation; D008099:Liver / Q000821:virology; D008168:Lung / Q000821:virology; D011201:Poultry Diseases / Q000382:microbiology / Q000473:pathology; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; C000600693:RstA protein, E Coli; D037521:Virulence Factors
keywords: Avian pathogenic Escherichia coli; Mutant; RstA; Virulence