title: Influence of the major nitrite transporter NirC on the virulence of a Swollen Head Syndrome avian pathogenic E. coli (APEC) strain.
abstract: Avian Pathogenic Escherichia coli (APEC) strains are extra-intestinal E. coli that infect poultry and cause diseases. Nitrite is a central branch-point in bacterial nitrogen metabolism and is used as a cytotoxin by macrophages. Unlike nitric oxide (NO), nitrite cannot diffuse across bacterial membrane cells. The NirC protein acts as a specific channel to facilitate the transport of nitrite into Salmonella and E. coli cells for nitrogen metabolism and cytoplasmic detoxification. NirC is also required for the pathogenicity of Salmonella by downregulating the production of NO by the host macrophages. Based on an in vitro microarray that revealed the overexpression of the nirC gene in APEC strain SCI-07, we constructed a nirC-deficient SCI-07 strain (ΔnirC) and evaluated its virulence potential using in vivo and in vitro assays. The final cumulative mortalities caused by mutant and wild-type (WT) were similar; while the ΔnirC caused a gradual increase in the mortality rate during the seven days recorded, the WT caused mortality up to 24h post-infection (hpi). Counts of the ΔnirC cells in the spleen, lung and liver were higher than those of the WT after 48 hpi but similar at 24 hpi. Although similar number of ΔnirC and WT cells was observed in macrophages at 3 hpi, there was higher number of ΔnirC cells at 16 hpi. The cell adhesion ability of the ΔnirC strain was about half the WT level in the presence and absence of alpha-D-mannopyranoside. These results indicate that the nirC gene influences the pathogenicity of SCI-07 strain.
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas-UNICAMP, PO Box 6109, Campinas, SP, Brazil. Electronic address: jackboldrin@hotmail.com.
authors.forename: Jacqueline Boldrin
authors.initials: JB
authors.lastname: de Paiva
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas-UNICAMP, PO Box 6109, Campinas, SP, Brazil.
authors.forename: Janaína Luisa
authors.initials: JL
authors.lastname: Leite
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas-UNICAMP, PO Box 6109, Campinas, SP, Brazil.
authors.forename: Livia Pilatti Mendes
authors.initials: LP
authors.lastname: da Silva
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas-UNICAMP, PO Box 6109, Campinas, SP, Brazil.
authors.forename: Thais Cabrera Galvão
authors.initials: TC
authors.lastname: Rojas
authors.affiliation: Department of Clinical Medicine, Faculty of Medical Sciences, State University of Campinas-UNICAMP, Campinas, SP, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: de Pace
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas-UNICAMP, PO Box 6109, Campinas, SP, Brazil.
authors.forename: Rogério Arcuri
authors.initials: RA
authors.lastname: Conceição
authors.affiliation: University of Texas Southwestern Medical Center, Dallas, TX 75390-9048, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Sperandio
authors.affiliation: Department of Genetics, Evolution and Bioagents, Institute of Biology, State University of Campinas-UNICAMP, PO Box 6109, Campinas, SP, Brazil. Electronic address: wds@unicamp.br.
authors.forename: Wanderley Dias
authors.initials: WD
authors.lastname: da Silveira
mesh_terms: D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion; D002645:Chickens / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D005347:Fibroblasts; D020869:Gene Expression Profiling / Q000662:veterinary; D015964:Gene Expression Regulation, Bacterial; D008264:Macrophages; D009573:Nitrites / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D011201:Poultry Diseases / Q000382:microbiology*; D017384:Sequence Deletion; D014774:Virulence; D037521:Virulence Factors
chemical_list: D027321:Anion Transport Proteins; D001426:Bacterial Proteins; C088104:NirC protein, Bacteria; D009573:Nitrites; D037521:Virulence Factors; C077481:Crl protein, Bacteria
keywords: APEC; Escherichia coli; Pathogenicity; Virulence; nirC