PMID:25487442

Citation	de Paiva, JB, Leite, JL, da Silva, LP, Rojas, TC, de Pace, F, Conceição, RA, Sperandio, V and da Silveira, WD (2015) Influence of the major nitrite transporter NirC on the virulence of a Swollen Head Syndrome avian pathogenic E. coli (APEC) strain. Vet. Microbiol. 175:123-31
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.
Links	PubMed Online version:10.1016/j.vetmic.2014.11.015
Keywords	Animals; Anion Transport Proteins/genetics; Anion Transport Proteins/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Cell Adhesion; Chickens/microbiology; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli/pathogenicity; Escherichia coli Infections/microbiology; Fibroblasts; Gene Expression Profiling/veterinary; Gene Expression Regulation, Bacterial; Macrophages; Nitrites/metabolism; Oligonucleotide Array Sequence Analysis/veterinary; Poultry Diseases/microbiology; Sequence Deletion; Virulence; Virulence Factors
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLX:E2QFM3		GO:0009405: pathogenesis	ECO:0000315:		P		Fig. S2. Survival rate of one-day-old chickens challenged with either Avian Pathogenic Escherichia coli (Strain: SCI-07 strain) nirC (major nitrite transporter) mutant, complemented or wild-type strains showed lower initial mortality rate; indicative of delayed or decreased pathogenicity.	complete CACAO 12446
ECOK1:A0A0H2Z3A5		GO:0044650: adhesion of symbiont to host cell	ECO:0000315:		P		Fig. 3. Quantification of the adhesion of Avian Pathogenic Escherichia coli (Strain: SCI-07 strain) nirC (major nitrite transporter) mutant, complemented or wild-type strains showed lower initial mortality rate; indicative of delayed or decreased pathogenicity.	complete CACAO 12450

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