Non‐pigment‐producing isolates of Aeromonas salmonicida subspecies salmonicida: isolation, identification, transmission and pathogenicity in Atlantic salmon, Salmo salar L.

Koppang, Erling Olaf; Fjølstad, Morten; Melgård, B; Vigerust, M; ørum, H S.

doi:10.1046/j.1365-2761.2000.00205.x

Cited by 17 publications

(9 citation statements)

References 21 publications

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“…salmonicida isolates lacking pigment production (Wiklund, Lönnström & Niiranen ; Koppang et al . ) and oxidase‐negative atypical isolates (Wiklund & Bylund ; Pedersen et al . ) have been reported, both of which contradict established diagnostic criteria (Fig.…”

Section: Discussionmentioning

confidence: 99%

vapA (A‐layer) typing differentiates Aeromonas salmonicida subspecies and identifies a number of previously undescribed subtypes

Gulla

Lund

Kristoffersen

et al. 2015

Journal of Fish Diseases

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Sequence variation in a region of the virulence array protein gene (vapA; A-layer) was assessed in 333 ('typical' and 'atypical') isolates of the fish pathogenic bacterium Aeromonas salmonicida. Resulting similarity dendrograms revealed extensive heterogeneity, with nearly all isolates belonging to either of 14 distinct clusters or A-layer types. All acknowledged A. salmonicida subspecies (except ssp. pectinolytica, from which no vapA sequence could be obtained) were clearly separated, and notably, all isolates phenotypically identified as ssp. salmonicida formed a distinct and exclusive A-layer type. Additionally, an array of un-subspeciated atypical strains formed several equally prominent clusters, demonstrating that the concept of typical/atypical A. salmonicida is inappropriate for describing the high degree of diversity evidently occurring outside ssp. salmonicida. Most representatives assessed in this study were clinical isolates of spatiotemporally diverse origins, and were derived from a variety of hosts. We observed that from several fish species or families, isolates predominantly belonged to certain A-layer types, possibly indicating a need for host-/A-layer type-specific A. salmonicida vaccines. All in all, A-layer typing shows promise as an inexpensive and rapid means of unambiguously distinguishing clinically relevant A. salmonicida subspecies, as well as presently un-subspeciated atypical strains.

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Section: Discussionmentioning

confidence: 99%

vapA (A‐layer) typing differentiates Aeromonas salmonicida subspecies and identifies a number of previously undescribed subtypes

Gulla

Lund

Kristoffersen

et al. 2015

Journal of Fish Diseases

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“…Phenotypical variation amongst subsp. salmonicida isolates is rare but has been described [ 31 ]. The increased resolution of M-CGH compared to phenotypic typing can be illustrated on consideration of strain N4705 which was considered an atypical strain on phenotypical grounds.…”

Section: Discussionmentioning

confidence: 99%

Comparative genomics profiling of clinical isolates of Aeromonas salmonicida using DNA microarrays

et al. 2006

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Background: Aeromonas salmonicida has been isolated from numerous fish species and shows wide variation in virulence and pathogenicity. As part of a larger research program to identify virulence genes and candidates for vaccine development, a DNA microarray was constructed using a subset of 2024 genes from the draft genome sequence of A. salmonicida subsp. salmonicida strain A449. The microarray included genes encoding known virulence-associated factors in A. salmonicida and homologs of virulence genes of other pathogens. We used microarray-based comparative genomic hybridizations (M-CGH) to compare selected A. salmonicida sub-species and other Aeromonas species from different hosts and geographic locations.

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“…The brownish melanin-like pigments formed by several microorganisms are believed to be a protective mechanism against oxidative radicals of the oxidative burst (de Cassia & Pombeiro-Sponchiado 2005); hence, it is likely that aeration induces their production. D-glucose may repress pigment formation (Altmann et al 1992, Koppang et al 2000, but as all the experiments were performed in LB 5 broth, which does not contain glucose, this has not influenced the results. The majority of the atypical strains in this study have been examined for caseinolytic activity by Gudmundsdóttir (1996); except for 3 strains, our reporting of positive and negative strains corresponds to the earlier finding.…”

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confidence: 99%

Quorum sensing signals are produced by Aeromonas salmonicida and quorum sensing inhibitors can reduce production of a potential virulence factor

Rasch¹,

Kastbjerg²,

Bruhn³

et al. 2007

Dis. Aquat. Org.

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Many pathogens control production of virulence factors by self-produced signals in a process called quorum sensing (QS). We demonstrate that acyl homoserine lactone (AHL) signals, which enable bacteria to express certain phenotypes in relation to cell density, are produced by a wide spectrum of Aeromonas salmonicida strains. All 31 typical strains were AHL producers as were 21 of 26 atypical strains, but on a strain population basis, production of virulence factors such as protease, lipase, A-layer or pigment did not correlate with the production and accumulation of AHLs in the growth medium. Pigment production was only observed in broth under highly aerated conditions. Quorum sensing inhibitors (QSIs) are compounds that specifically block QS systems without affecting bacterial growth and 2 such compounds, sulphur-containing AHL-analogues, reduced production of protease in a typical strain of Aeromonas salmonicida. The most efficient compound N-(heptylsulfanylacetyl)-L-homoserine lactone (HepS-AHL), reduced protease production by a factor of 10. Five extracellular proteases were detected on gelatin-containing sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) gels and 3 of these were completely down regulated by HepS-AHL. Hence, QSIs can curb virulence in some strains and could potentially be pursued as bacterial disease control measures in aquaculture.KEY WORDS: Acylated homoserine lactones · Aeromonas salmonicida · Pigment · Protease · Quorum sensing inhibitors Resale or republication not permitted without written consent of the publisherDis Aquat Org 78: [105][106][107][108][109][110][111][112][113] 2007 2005). QS controls several of the putative virulence factors in aquatic bacteria, such as protease in V. anguillarum (Croxatto et al. 2002) and A. hydrophila (Swift et al. 1999), siderophores in V. harveyi (Lilley & Bassler 2000), and haemolysin in V. vulnificus (Kim et al. 2003). However, the role of the QS systems in expression of virulence in fish pathogenic bacteria is not at present fully understood.Quorum sensing inhibitors (QSIs) are compounds that antagonise bacterial QS systems without affecting growth of the bacteria (Smith et al. 2003, Castang et al. 2004, Rasmussen et al. 2005a. QSIs reduce production of toxin from Vibrio harveyi (Manefield et al. 2000) and treatment with a QSI, the halogenated furanone C-30, reduced accumulated mortality in rainbow trout infected with V. anguillarum (Rasch et al. 2004). However higher concentrations of furanone C-30 resulted in rapid fish death (Rasch et al. 2004), which stressed the need to explore less toxic QSI compounds for treatment. Sulfonated analogues of AHL compounds are such less toxic compounds ) and can inhibit several QS systems (Koch et al. 2005). In the present study, we address the possible involvement of QS systems in expression of virulence factors of Aeromonas salmonicida and determine to what extent QSI compounds affect production of virulence factors.Aeromonas salmonicida is the bacterial agent associated with ...

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Non‐pigment‐producing isolates of Aeromonas salmonicida subspecies salmonicida: isolation, identification, transmission and pathogenicity in Atlantic salmon, Salmo salar L.

Cited by 17 publications

References 21 publications

vapA (A‐layer) typing differentiates Aeromonas salmonicida subspecies and identifies a number of previously undescribed subtypes

vapA (A‐layer) typing differentiates Aeromonas salmonicida subspecies and identifies a number of previously undescribed subtypes

Comparative genomics profiling of clinical isolates of Aeromonas salmonicida using DNA microarrays

Quorum sensing signals are produced by Aeromonas salmonicida and quorum sensing inhibitors can reduce production of a potential virulence factor

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