Draft Genome Sequence of the Fish Pathogen Piscirickettsia salmonis

Eppinger, Mark; McNair, Katelyn; Zogaj, Xhavit; Dinsdale, Elizabeth A.; Edwards, Robert A.; Klose, Karl E.

doi:10.1128/genomea.00926-13

Cited by 18 publications

(14 citation statements)

References 13 publications

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“…1). Moreover, we have demonstrated that all characterized P. salmonis strains have flagellar genes and share the same genetic organization (Eppinger et al 2013, Bohle et al 2014, Yañez et al 2014, Pulgar et al 2015. Our results suggest that P. salmonis has the potential to develop a flagellum controlled by this transcriptional cascade.…”

Section: Discussionmentioning

confidence: 56%

“…Once the genes were confirmed, the CLC Main Workbench 5 software (www.clcbio.com) was used to complement sequence analysis, specifically for accurate alignments, and to determine the putative operon organization of flagellar genes in P. salmonis. Finally, flagellar gene organization was compared between different P. salmonis strains using recently reported genomes (Eppinger et al 2013, Bohle et al 2014, Yañez et al 2014, Pulgar et al 2015.…”

Section: Screening Of the Piscirickettsia Salmonis Genomementioning

confidence: 99%

“…Secondly, 2 different functional chromosomal toxinantitoxin modules are particularly upregulated under stress, with distinctive features contributing to the bacterium's adaptation to environmental cues (Gó -mez et al 2011, Marshall et al 2012. The search for new pathogenic features has been facilitated by the recent genome sequencing of P. salmonis isolates (Eppinger et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Carril

Gómez²,

Marshall³

2017

Dis. Aquat. Org.

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The Piscirickettsia salmonis genome was screened to evaluate potential flagellarelated open reading frames, as well as their genomic organization and eventual expression. A complete and organized set of flagellar genes was found for P. salmonis, although no structural flagellum has ever been reported for this bacterium. To gain further understanding, the hierarchical flagellar cascade described for Legionella pneumophila was used as a reference model for putative analysis in P. salmonis. Specifically, 5 of the most relevant genes from this cascade were chosen, including 3 regulatory genes (fleQ, triggers the cascade; fliA, regulates the σ28-coding gene; and rpoN, an RNA polymerase-dependent gene) and 2 terminal structural genes (flaA and flaB, flagellin and a flagellin-like protein, respectively). Kinetic experiments evaluated gene expressions over time, with P. salmonis assessed in 2 liquid, cell-free media and during infection of the SHK-1 fish cell line. Under all conditions, the 5 target genes were primarily expressed during early growth/infection and were differentially expressed when bacteria encountered environmental stress (i.e. a high-salt concentration). Intriguingly, the flagellin monomer was fully expressed under all growth conditions and was located near the bacterial membrane. While no structural flagellum was detected under any condition, the recombinant flagellin monomer induced a proinflammatory response in SHK-1 cells, suggesting a possible immunomodulatory function. The potential implications of these observations are discussed in the context of P. salmonis biology and pathogenic potential.

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Section: Discussionmentioning

confidence: 56%

Section: Screening Of the Piscirickettsia Salmonis Genomementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Expression of flagellin and key regulatory flagellar genes in the non-motile bacterium Piscirickettsia salmonis

Carril

Gómez²,

Marshall³

2017

Dis. Aquat. Org.

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Section: Discussionmentioning

confidence: 99%

“…Most crucial would be a formal polyphasic approach comparing TRLO, P. salmonis and, if possible, P. salmonis-like organisms (Chen et al 2000a,b, Mauel et al 2003, McCarthy et al 2005 incorporating methods secondary to 16S rDNA or multilocus sequence analysis such as DNA:DNA hybridisations (Rosselló-Mora & Amann 2001, Stackebrandt et al 2002, Tindall et al 2010 or whole genome sequence comparison (Whitman 2015). The latter is now very realistic given that 2 P. salmonis genomes have already been sequenced and published (Eppinger et al 2013, Yañez et al 2014.In summary, evidence is presented showing that TRLO comprises a serotypically diverse group of novel bacteria capable of in vitro growth in an intracellular or extracellular environment. Evidence of phylogenetic, phenotypic and antigenic differences justifies the sustained use of the TRLO name and separation from P. salmonis, but further detailed analyses are required for formal taxonomic placement of TRLO.…”

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confidence: 99%

Isolation of Tasmanian Rickettsia-like organism (RLO) from farmed salmonids: identification of multiple serotypes and confirmation of pathogenicity

Morrison¹,

Young²,

Knowles³

et al. 2016

Dis. Aquat. Org.

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Atlantic salmon Salmo salar L. farmed in south-east Tasmania, Australia, are susceptible to infection by the Tasmanian Rickettsia-like organism (TRLO), a Gram-negative bacterium. Here, we report the first isolation of TRLO from south-east Tasmania in pure culture and show that the bacterium is culturable on both specialised enriched agar and in cell culture using the CHSE-214 cell line. In vitro cultured TRLO was used to reproducibly elicit disease in Atlantic salmon parr held in fresh water. In inoculated fish, TRLO was observed intracytoplasmically in peripheral blood leucocytes, suggesting that these cells are responsible for haematogenous dispersal of the bacterium within the host. Fish with experimentally induced disease presented with gross and histopathological changes similar to TRLO-infected fish at commercial marine farms. TRLO was also isolated in culture from farmed Atlantic salmon in the Tamar River and Macquarie Harbour production areas in Tasmania, both of which have no history of TRLO-associated disease. These TRLO isolates appear to be serologically distinct from each other as well as from isolates obtained from south-east Tasmania, linking each serotype to a specific geographical location within Tasmania. Despite the lack of clinical evidence of TRLO-linked disease in fish grown in the Tamar River and Macquarie Harbour, experimental infection trials demonstrably showed the pathogenic potential of these TRLO serovars. Together, these data provide evidence that TRLO is a fastidious, facultative intracellular bacterium and confirm TRLO as a pathogen of Atlantic salmon, causing a disease designated Tasmanian salmonid rickettsiosis.KEY WORDS: Rickettsia-like organism · TRLO · Atlantic salmon · Salmo salar · Culture · Pathogenicity · Tasmania Resale or republication not permitted without written consent of the publisherDis Aquat Org 122: [85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103] 2016 RLO (Khoo et al. 1995, Athanassopoulou et al. 2004, Corbeil et al. 2005, Wu et al. 2005 or P. salmonis-like organism (Antonio et al. 2000, Chen et al. 2000a,b, Mauel et al. 2003 until their taxonomic status can be formally resolved. This includes the Tasmanian RLO (TRLO), a bacte rium detected in Atlantic salmon Salmo salar L. farmed on the south-east coast of Tasmania, Austra lia (Corbeil et al. 2005).TRLO is an intracellular, Gram-negative coccoid bacterium that emerged in the summer of 2001 (Department of Primary Industries, Parks, Water and Environment [DPIPWE] unpublished data). Since then, TRLO has been implicated in minor sporadic outbreaks of disease which have typically coincided with the annual peak in water temperature. The disease is characterised by a high morbidity rate which results in significant production loss through reduced feed intake but relatively low mortality, less than 10% of affected stock. During outbreaks, affected fish are commonly co-infected with the Tasmanian Atlantic salmon reovirus (TSRV; Zainathan et al. 2015), and it is not known wh...

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