title: The virulence factor ychO has a pleiotropic action in an Avian Pathogenic Escherichia coli (APEC) strain.
abstract: BACKGROUND
  Avian pathogenic Escherichia coli strains cause extraintestinal diseases in birds, leading to substantial economic losses to the poultry industry worldwide. Bacteria that invade cells can overcome the host humoral immune response, resulting in a higher pathogenicity potential. Invasins are members of a large family of outer membrane proteins that allow pathogen invasion into host cells by interacting with specific receptors on the cell surface.
  
  
  RESULTS
  An in silico analysis of the genome of a septicemic APEC strain (SEPT362) demonstrated the presence of a putative invasin homologous to the ychO gene from E. coli str. K-12 substr. MG1655. In vitro and in vivo assays comparing a mutant strain carrying a null mutation of this gene, a complemented strain, and its counterpart wild-type strain showed that ychO plays a role in the pathogenicity of APEC strain SEPT362. In vitro assays demonstrated that the mutant strain exhibited significant decreases in bacterial adhesiveness and invasiveness in chicken cells and biofilm formation. In vivo assay indicated a decrease in pathogenicity of the mutant strain. Moreover, transcriptome analysis demonstrated that the ychO deletion affected the expression of 426 genes. Among the altered genes, 93.66% were downregulated in the mutant, including membrane proteins and metabolism genes.
  
  
  CONCLUSIONS
  The results led us to propose that gene ychO contributes to the pathogenicity of APEC strain SEPT362 influencing, in a pleiotropic manner, many biological characteristics, such as adhesion and invasion of in vitro cultured cells, biofilm formation and motility, which could be due to the possible membrane location of this protein. All of these results suggest that the absence of gene ychO would influence the virulence of the APEC strain herein studied.
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology (P.O.Box: 6109), State University of Campinas - UNICAMP (ZIP Code 13083-970), Campinas, São Paulo, Brazil.
authors.forename: Livia
authors.initials: L
authors.lastname: Pilatti
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology (P.O.Box: 6109), State University of Campinas - UNICAMP (ZIP Code 13083-970), Campinas, São Paulo, Brazil.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Boldrin de Paiva
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology (P.O.Box: 6109), State University of Campinas - UNICAMP (ZIP Code 13083-970), Campinas, São Paulo, Brazil.
authors.forename: Thaís Cabrera Galvão
authors.initials: TC
authors.lastname: Rojas
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology (P.O.Box: 6109), State University of Campinas - UNICAMP (ZIP Code 13083-970), Campinas, São Paulo, Brazil.
authors.forename: Janaína Luisa
authors.initials: JL
authors.lastname: Leite
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology (P.O.Box: 6109), State University of Campinas - UNICAMP (ZIP Code 13083-970), Campinas, São Paulo, Brazil.
authors.forename: Rogério Arcuri
authors.initials: RA
authors.lastname: Conceição
authors.affiliation: Department of Microbiology, Center of Biological Sciences, State University of Londrina (UEL), Londrina, Paraná, Brazil.
authors.forename: Gerson
authors.initials: G
authors.lastname: Nakazato
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology (P.O.Box: 6109), State University of Campinas - UNICAMP (ZIP Code 13083-970), Campinas, São Paulo, Brazil. wds@unicamp.br.
authors.forename: Wanderley
authors.initials: W
authors.lastname: Dias da Silveira
mesh_terms: D000818:Animals; D002645:Chickens; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011201:Poultry Diseases / Q000382:microbiology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D037521:Virulence Factors; C000611539:YchO protein, E coli
keywords: APEC; Escherichia coli; Pathogenicity; Virulence; ychO