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H-NS is a repressor of major virulence gene loci in Vibrio parahaemolyticus.

Sun F, Zhang Y, Qiu Y, Yang H, Yang W, Yin Z, Wang J, Yang R, Xia P, Zhou D - Front Microbiol (2014)

Bottom Line: Vibrio parahaemolyticus, a leading cause of seafood-associated diarrhea and gastroenteritis, harbors three major virulence gene loci T3SS1, Vp-PAI (T3SS1+tdh2) and T6SS2.H-NS appears to act as a major repressor of the virulence of this pathogen.Date presented here would promote us to gain a deeper understanding of H-NS-mediated silencing of horizontally acquired virulence loci in V. parahaemolyticus.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, Southwest Hospital, Third Military Medical University Chongqing, China.

ABSTRACT
Vibrio parahaemolyticus, a leading cause of seafood-associated diarrhea and gastroenteritis, harbors three major virulence gene loci T3SS1, Vp-PAI (T3SS1+tdh2) and T6SS2. As showing in this study, the nucleoid-associated DNA-binding regulator H-NS binds to multiple promoter-proximal regions in each of the above three loci to repress their transcription, and moreover H-NS inhibits the cytotoxicitiy, enterotoxicity, hemolytic activity, and mouse lethality of V. parahaemolyticus. H-NS appears to act as a major repressor of the virulence of this pathogen. Date presented here would promote us to gain a deeper understanding of H-NS-mediated silencing of horizontally acquired virulence loci in V. parahaemolyticus.

No MeSH data available.


Related in: MedlinePlus

Involvement of H-NS in virulence. The cytotoxicity against cultured RAW 264.7 cells (A) was evaluated in terms of the release of LDH. The hemolytic activity against RECs (B) was evaluated by detecting the release of hemoglobin. The enterotoxicity was evaluated by determining the fluid accumulation in the ileal loop (C). The murine survival rate after the intraperitoneal infection was measured to determine the lethality in mice (D).
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Figure 1: Involvement of H-NS in virulence. The cytotoxicity against cultured RAW 264.7 cells (A) was evaluated in terms of the release of LDH. The hemolytic activity against RECs (B) was evaluated by detecting the release of hemoglobin. The enterotoxicity was evaluated by determining the fluid accumulation in the ileal loop (C). The murine survival rate after the intraperitoneal infection was measured to determine the lethality in mice (D).

Mentions: WT/pBAD33, Δhns/pBAD33, and Δhns/pBAD33-hns were employed in all the phenotype assays, which would normalize the effects of chloramphenicol and rabinose, when added in cell cultures, on bacterial growth and physiology. First, V. parahaemolyticus-induced cytotoxic activity against the macrophage-like cell line RAW 264.7 was evaluated in terms of the release of cytosolic LDH from cultured cells (Figure 1A). When RAW 264 cells were infected with Δhns/pBAD33, the cytotoxicitiy was significantly enhanced compared with that of WT/pBAD33 or Δhns/pBAD33-hns. Second, the hemolytic activities against RECs were compared between the above three strains (Figure 1B). The hemolytic activity of Δhns/pBAD33 was significantly higher than that of WT/pBAD33 or Δhns/pBAD33-hns. Third, the fluid accumulating activities of the above three strains in rabbit ileal loops were compared to investigate the enterotoxicities of these strains (Figure 1C). Δhns/pBAD33 showed a significant increase in fluid accumulation compared with WT/pBAD33 and Δhns/pBAD33-hns. Finally, the survival rates of mice infected intraperitoneally with each of the above three strains were determined (Figure 1D), and the lethality in mice for Δhns/pBAD33 was significantly elevated relative to WT. Δhns/pBAD33-hns exhibited a curve of murine survival rates similar to that of Δhns/pBAD33 (data not shown), which might be due to lack of arabinose for efficiently inducing expression of H-NS or that of antibiotics for maintaining replication of pBAD33-hns (for in trans complementation) during infection in mice. Taken together, H-NS inhibits the cytotoxicitiy, enterotoxicity, hemolytic activity, and mouse lethality of V. parahaemolyticus.


H-NS is a repressor of major virulence gene loci in Vibrio parahaemolyticus.

Sun F, Zhang Y, Qiu Y, Yang H, Yang W, Yin Z, Wang J, Yang R, Xia P, Zhou D - Front Microbiol (2014)

Involvement of H-NS in virulence. The cytotoxicity against cultured RAW 264.7 cells (A) was evaluated in terms of the release of LDH. The hemolytic activity against RECs (B) was evaluated by detecting the release of hemoglobin. The enterotoxicity was evaluated by determining the fluid accumulation in the ileal loop (C). The murine survival rate after the intraperitoneal infection was measured to determine the lethality in mice (D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4264476&req=5

Figure 1: Involvement of H-NS in virulence. The cytotoxicity against cultured RAW 264.7 cells (A) was evaluated in terms of the release of LDH. The hemolytic activity against RECs (B) was evaluated by detecting the release of hemoglobin. The enterotoxicity was evaluated by determining the fluid accumulation in the ileal loop (C). The murine survival rate after the intraperitoneal infection was measured to determine the lethality in mice (D).
Mentions: WT/pBAD33, Δhns/pBAD33, and Δhns/pBAD33-hns were employed in all the phenotype assays, which would normalize the effects of chloramphenicol and rabinose, when added in cell cultures, on bacterial growth and physiology. First, V. parahaemolyticus-induced cytotoxic activity against the macrophage-like cell line RAW 264.7 was evaluated in terms of the release of cytosolic LDH from cultured cells (Figure 1A). When RAW 264 cells were infected with Δhns/pBAD33, the cytotoxicitiy was significantly enhanced compared with that of WT/pBAD33 or Δhns/pBAD33-hns. Second, the hemolytic activities against RECs were compared between the above three strains (Figure 1B). The hemolytic activity of Δhns/pBAD33 was significantly higher than that of WT/pBAD33 or Δhns/pBAD33-hns. Third, the fluid accumulating activities of the above three strains in rabbit ileal loops were compared to investigate the enterotoxicities of these strains (Figure 1C). Δhns/pBAD33 showed a significant increase in fluid accumulation compared with WT/pBAD33 and Δhns/pBAD33-hns. Finally, the survival rates of mice infected intraperitoneally with each of the above three strains were determined (Figure 1D), and the lethality in mice for Δhns/pBAD33 was significantly elevated relative to WT. Δhns/pBAD33-hns exhibited a curve of murine survival rates similar to that of Δhns/pBAD33 (data not shown), which might be due to lack of arabinose for efficiently inducing expression of H-NS or that of antibiotics for maintaining replication of pBAD33-hns (for in trans complementation) during infection in mice. Taken together, H-NS inhibits the cytotoxicitiy, enterotoxicity, hemolytic activity, and mouse lethality of V. parahaemolyticus.

Bottom Line: Vibrio parahaemolyticus, a leading cause of seafood-associated diarrhea and gastroenteritis, harbors three major virulence gene loci T3SS1, Vp-PAI (T3SS1+tdh2) and T6SS2.H-NS appears to act as a major repressor of the virulence of this pathogen.Date presented here would promote us to gain a deeper understanding of H-NS-mediated silencing of horizontally acquired virulence loci in V. parahaemolyticus.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacy, Southwest Hospital, Third Military Medical University Chongqing, China.

ABSTRACT
Vibrio parahaemolyticus, a leading cause of seafood-associated diarrhea and gastroenteritis, harbors three major virulence gene loci T3SS1, Vp-PAI (T3SS1+tdh2) and T6SS2. As showing in this study, the nucleoid-associated DNA-binding regulator H-NS binds to multiple promoter-proximal regions in each of the above three loci to repress their transcription, and moreover H-NS inhibits the cytotoxicitiy, enterotoxicity, hemolytic activity, and mouse lethality of V. parahaemolyticus. H-NS appears to act as a major repressor of the virulence of this pathogen. Date presented here would promote us to gain a deeper understanding of H-NS-mediated silencing of horizontally acquired virulence loci in V. parahaemolyticus.

No MeSH data available.


Related in: MedlinePlus