Difference in genes between a high virulence strain G4 and a low virulence strain G18 of Flavobacterium columnare by using suppression subtractive hybridization

Li, N; Zhang, Jiaolong; Zhang, L Q; Nie, Pin

doi:10.1111/j.1365-2761.2009.01132.x

Cited by 12 publications

(5 citation statements)

References 38 publications

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“…As an important component of the iron uptake system, several TonB-dependent receptors were reported to have relevance in pathogen pathogenicity (Alvarez et al 2008, Tauseef et al 2011. In a comparative study of Flavobacterium columnare strains with high and low virulence, Li et al (2010) identified 3 tdr genes in the high virulence strain but not in the low virulence strain. In a study of Bordetella pertussis, inactivation of a TonB-dependent receptor gene, fauA, was found to have a profound impact on in vivo growth and survival (Brickman & Armstrong 2007).…”

Section: Discussionmentioning

confidence: 99%

Identification and analysis of three virulence-associated TonB-dependent outer membrane receptors of Pseudomonas fluorescens

Zhang

Lu²,

Sun³

2014

Dis. Aquat. Org.

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Pseudomonas fluorescens is a Gram-negative bacterium that can infect a wide range of farmed fish. However, very little is known about the virulence mechanism of P. fluorescens as a fish pathogen. In this study, we identified and analyzed 3 TonB-dependent outer membrane receptors (TDRs) from a pathogenic P. fluorescens strain isolated from fish. In silico analysis revealed that all 3 proteins (named Tdr1 to 3) possess structural domains typical of TDRs. Quantitative real time RT-PCR analysis showed that tdr1, tdr2, and tdr3 expressions were upregulated under iron-depleted conditions. Compared to the wild type, mutants defective in tdr1, tdr2, and tdr3 were retarded in growth to different extents. Infection in a turbot Scophthalmus maximus model showed that all 3 mutants were impaired in their ability to desseminate into and colonize host tissues. In addition, the tdr1 and tdr3 mutants exhibited significantly reduced virulence. When used as subunit vaccines, purified recombinant proteins of Tdr1, Tdr2, and, in particular, Tdr3 elicited significant protection in turbot against lethal P. fluorescens challenge. The vaccinated fish produced specific serum antibodies, which, when incubated with P. fluorescens, blocked infection of P. fluorescens in fish cells. Together these results indicate that Tdr1, Tdr2, and Tdr3 are iron-regulated factors that participate in bacterial virulence and induce protective immunity as subunit vaccines.

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Section: Discussionmentioning

confidence: 99%

Identification and analysis of three virulence-associated TonB-dependent outer membrane receptors of Pseudomonas fluorescens

Zhang

Lu²,

Sun³

2014

Dis. Aquat. Org.

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“…Earlier studies using subtractive hybridization documented variation in transcripts related to iron transport between two F. columnare strains with different virulence levels in grass carp (Li et al . ). More recently, one study identified the presence of iron uptake machinery, determined that iron levels in media were found to be crucial for growth in vitro , and found that F. columnare can synthesize siderophores which chelate and facilitate iron uptake (Guan et al .…”

Section: Introductionmentioning

confidence: 97%

A comparison of high‐ and low‐virulence Flavobacterium columnare strains reveals differences in iron acquisition components and responses to iron restriction

Beck

Farmer

et al. 2015

Journal of Fish Diseases

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Flavobacterium columnare, the causative agent of columnaris disease causes substantial mortality worldwide in numerous freshwater finfish species. Due to its global significance, an improved understanding of the factors that contribute to virulence is urgently needed. In a laboratory challenge, we found that significantly greater mortality was observed in channel catfish Ictalurus punctatus (Rafinesque) challenged with isolate LSU-066-04 (LSU) as compared to fish challenged with isolate LV-359-01 (LV). Strikingly, mortality was 100% in LSU-challenged fish, with all fish dying within the first 24 h after challenge, while mortality in the LV-challenged group was significantly lower with 26.7% of fish dying on days 1-4 post-challenge. There were no differences in initial bacterial adhesion between the isolates at 1-2 h post-challenge; however, by 4 h LSU-challenged fish had a greater bacterial load on the gill. Next, to better understand this variation in virulence, we examined transcriptional and functional attributes related to iron acquisition. The isolates were differentially sensitive to iron restriction both in vitro and in vivo and the basal expression of TonB family member genes and a ferroxidase gene differed significantly. Our findings provide new insight into iron uptake and pathogen virulence, and offer promising new targets for columnaris prevention and treatment.

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“…For example, in low‐iron conditions, E. coli will synthesize outer membrane proteins for upregulation and Pseudomonas fluorescens will increase TonB‐dependent OMR (TdrA; Hu et al., 2012; Sigel & Payne, 1982). The outer membrane proteins and TonB‐dependent receptors are targets for new antibiotic therapies, and changes to these proteins may lead to avirulent pathogens (Li et al., 2010; Moeck & Coulton, 2002).…”

Section: Introductionmentioning

confidence: 99%

Quantification and comparison of gene expression associated with iron regulation and metabolism in a virulent and attenuated strain of Flavobacterium psychrophilum

Bruce

Sudheesh

et al. 2021

Journal of Fish Diseases

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Iron is essential for growth and virulence in most pathogenic bacterial strains. In some cases, the hosts for these pathogenic bacteria develop specialized strategies to sequester iron and limit infectivity. This in turn may result in the invading pathogens utilizing high‐affinity iron transport mechanisms, such as the use of iron‐chelating siderophores, to extend beyond the host defences. Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease (BCWD) in salmonids, relies on iron metabolism for infectivity, and the genome of the model CSF‐259‐93 strain has recently been made available. Further, this strain serves as a parent strain for a live‐attenuated vaccine strain, B.17, which has been shown to provide rainbow trout with protection against BCWD. To elucidate specific gene expression responses to iron metabolism and compare strain differences, both F. psychrophilum strains were grown under iron‐limiting conditions and 26 genes related to iron metabolism were mapped for 96 hr in culture via qPCR analyses. Results indicate increased production of the ferrous iron transport protein B (FITB; p =.008), and ferric receptor CfrA (FR 1; p =.012) in the wild‐type CSF‐259‐93 strain at 72 hr and 96 hr post‐exposure to iron‐limiting media. In the B.17 vaccine strain, siderophore synthase (SS) expression was found to be downregulated at 72 hr, in comparison with 0h (p =.018). When strains were compared, FITB (p =.021), FR1 (p =.009) and SS (p =.016) were also elevated in B.17 at 0 hr and TonB outer protein membrane receptor 1 (TBomr1; p =.005) had a lower expression at 96 hr. Overall, this study demonstrated strain‐related gene expression changes in only a fraction of the iron metabolism genes tested; however, results provide insight on potential virulence mechanisms and clarification on iron‐related gene expression for F. psychrophilum.

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Difference in genes between a high virulence strain G₄ and a low virulence strain G₁₈ of Flavobacterium columnare by using suppression subtractive hybridization

Cited by 12 publications

References 38 publications

Identification and analysis of three virulence-associated TonB-dependent outer membrane receptors of Pseudomonas fluorescens

Identification and analysis of three virulence-associated TonB-dependent outer membrane receptors of Pseudomonas fluorescens

A comparison of high‐ and low‐virulence Flavobacterium columnare strains reveals differences in iron acquisition components and responses to iron restriction

Quantification and comparison of gene expression associated with iron regulation and metabolism in a virulent and attenuated strain of Flavobacterium psychrophilum

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