Aerobic Gram-Positive Rods and Cocci

Austin, Brian; Austin, Dawn A.

doi:10.1007/978-3-319-32674-0_3

Cited by 11 publications

(15 citation statements)

References 307 publications

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“…Further, this reveals that the BKD-dependent response in Atlantic salmon head kidney can be influenced by the level of infection, and fish with different R. salmoninarum levels may have distinct transcriptional response patterns. There was a larger number of DEPs in the L-BKD group (7,729 DEPs) compared to the H-BKD group (6,766 DEPs), and 357 differentially expressed between the H-BKD and L-BKD groups. Since R. salmoninarum has immunomodulatory effects on its host (10), the infection level-dependent BKD responses of Atlantic salmon in this study may be related to host-pathogen interactions.…”

Section: Discussionmentioning

confidence: 88%

“…Renibacterium salmoninarum is a Gram-positive intracellular pathogen that causes Bacterial Kidney Disease (BKD) in Atlantic salmon and other salmonids [e.g., sockeye salmon (Oncorhynchus nerka) and rainbow trout (O. mykiss)] (6). BKD has been reported in Canada, Chile and several other countries worldwide (6,7), and can cause up to 40% cumulative mortality in farmed Atlantic salmon (8, 9).…”

Section: Introductionmentioning

confidence: 99%

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Transcriptomic Profiling of the Adaptive and Innate Immune Responses of Atlantic Salmon to Renibacterium salmoninarum Infection

et al. 2020

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Bacterial Kidney Disease (BKD), which is caused by a Gram-positive, intracellular bacterial pathogen (Renibacterium salmoninarum), affects salmonids including Atlantic salmon (Salmo salar). However, the transcriptome response of Atlantic salmon to BKD remained unknown before the current study. We used a 44K salmonid microarray platform to characterise the global gene expression response of Atlantic salmon to BKD. Fish (∼54 g) were injected with a dose of R. salmoninarum (H-2 strain, 2 × 10 8 CFU per fish) or sterile medium (control), and then head kidney samples were collected at 13 days post-infection/injection (dpi). Firstly, infection levels of individuals were determined through quantifying the R. salmoninarum level by RNA-based TaqMan qPCR assays. Thereafter, based on the qPCR results for infection level, fish (n = 5) that showed no (control), higher (H-BKD), or lower (L-BKD) infection level at 13 dpi were subjected to microarray analyses. We identified 6,766 and 7,729 differentially expressed probes in the H-BKD and L-BKD groups, respectively. There were 357 probes responsive to the infection level (H-BKD vs. L-BKD). Several adaptive and innate immune processes were dysregulated in R. salmoninarum-infected Atlantic salmon. Adaptive immune pathways associated with lymphocyte differentiation and activation (e.g., lymphocyte chemotaxis, T-cell activation, and immunoglobulin secretion), as well as antigen-presenting cell functions, were shown to be differentially regulated in response to BKD. The infection level-responsive transcripts were related to several mechanisms such as the JAK-STAT signalling pathway, B-cell differentiation and interleukin-1 responses. Sixty-five microarray-identified transcripts were subjected to qPCR validation, and they showed the same fold-change direction as microarray results. The qPCRvalidated transcripts studied herein play putative roles in various immune processes including pathogen recognition (e.g., tlr5), antibacterial activity (e.g., hamp and camp), regulation of immune responses (e.g., tnfrsf11b and socs1), T-/B-cell differentiation (e.g., ccl4, irf1 and ccr5), T-cell functions (e.g., rnf144a, il13ra1b and tnfrsf6b), and Eslamloo et al. Atlantic Salmon Response to BKD antigen-presenting cell functions (e.g., fcgr1). The present study revealed diverse immune mechanisms dysregulated by R. salmoninarum in Atlantic salmon, and enhanced the current understanding of Atlantic salmon response to BKD. The identified biomarker genes can be used for future studies on improving the resistance of Atlantic salmon to BKD.

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Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Transcriptomic Profiling of the Adaptive and Innate Immune Responses of Atlantic Salmon to Renibacterium salmoninarum Infection

et al. 2020

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“…Renibacterium salmoninarum , a fastidious Gram-positive bacterium and a member of the Micrococcaceae family ( Fryer and Lannan, 1993 ), is the cause of BKD in salmonids. This bacterium can infect various salmonid species [e.g., sockeye salmon ( Oncorhynchus nerka ) and Atlantic salmon] in both fresh and marine water ( Austin and Austin, 2016 ; Eslamloo et al, 2020a ). Also, R. salmoninarum can be both horizontally and vertically transmitted ( Hall et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin

Emam

Eslamloo

Caballero‐Solares

et al. 2022

Front. Mol. Biosci.

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We investigated the immunomodulatory effect of varying levels of dietary ω6/ω3 fatty acids (FA) on Atlantic salmon (Salmo salar) antibacterial response. Two groups were fed either high-18:3ω3 or high-18:2ω6 FA diets for 8 weeks, and a third group was fed for 4 weeks on the high-18:2ω6 diet followed by 4 weeks on the high-18:3ω3 diet and termed “switched-diet”. Following the second 4 weeks of feeding (i.e., at 8 weeks), head kidney tissues from all groups were sampled for FA analysis. Fish were then intraperitoneally injected with either a formalin-killed Renibacterium salmoninarum bacterin (5 × 107 cells mL−1) or phosphate-buffered saline (PBS control), and head kidney tissues for gene expression analysis were sampled at 24 h post-injection. FA analysis showed that the head kidney profile reflected the dietary FA, especially for C18 FAs. The qPCR analyses of twenty-three genes showed that both the high-ω6 and high-ω3 groups had significant bacterin-dependent induction of some transcripts involved in lipid metabolism (ch25ha and lipe), pathogen recognition (clec12b and tlr5), and immune effectors (znrf1 and cish). In contrast, these transcripts did not significantly respond to the bacterin in the “switched-diet” group. Concurrently, biomarkers encoding proteins with putative roles in biotic inflammatory response (tnfrsf6b) and dendritic cell maturation (ccl13) were upregulated, and a chemokine receptor (cxcr1) was downregulated with the bacterin injection regardless of the experimental diets. On the other hand, an inflammatory regulator biomarker, bcl3, was only significantly upregulated in the high-ω3 fed group, and a C-type lectin family member (clec3a) was only significantly downregulated in the switched-diet group with the bacterin injection (compared with diet-matched PBS-injected controls). Transcript fold-change (FC: bacterin/PBS) showed that tlr5 was significantly over 2-fold higher in the high-18:2ω6 diet group compared with other diet groups. FC and FA associations highlighted the role of DGLA (20:3ω6; anti-inflammatory) and/or EPA (20:5ω3; anti-inflammatory) vs. ARA (20:4ω6; pro-inflammatory) as representative of the anti-inflammatory/pro-inflammatory balance between eicosanoid precursors. Also, the correlations revealed associations of FA proportions (% total FA) and FA ratios with several eicosanoid and immune receptor biomarkers (e.g., DGLA/ARA significant positive correlation with pgds, 5loxa, 5loxb, tlr5, and cxcr1). In summary, dietary FA profiles and/or regimens modulated the expression of some immune-relevant genes in Atlantic salmon injected with R. salmoninarum bacterin. The modulation of Atlantic salmon responses to bacterial pathogens and their associated antigens using high-ω6/high-ω3 diets warrants further investigation.

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“…Renibacterium salmoninarum is a Gram‐positive intracellular pathogen that causes the chronic granulomatous disease known as bacterial kidney disease (BKD), or renibacteriosis, in wild/feral and farmed salmon and trout worldwide (see review by Austin & Austin, 2016; Wiens, 2011). This bacterial pathogen can cause mortality rates as high as 80% (Evenden et al, 1993) in hatchery‐cultured freshwater and seawater salmonids.…”

Section: Introductionmentioning

confidence: 99%

Comparative pan‐genomic analysis of 51 Renibacterium salmoninarum indicates heterogeneity in the principal virulence factor, the 57 kDa protein

Saldarriaga‐Córdoba

Avendaño‐Herrera

2022

Journal of Fish Diseases

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Renibacterium salmoninarum, a Gram‐positive intracellular pathogen, is the causative agent of bacterial kidney disease (BKD), the impacts of which are high mortalities and economic losses for the salmon industry. This study provides novel analyses for the whole‐genome sequences of 50 R. salmoninarum isolates and the reference strain ATCC 33209 using a pan‐genomic approach to elucidate phylogenomic relationships and identify unique and shared genes associated with pathogenicity and infection mechanisms. Genome size varied from 3,061,638 to 3,155,332 bp; gene count from 3452 to 3580; and predicted coding sequences from 3402 to 3527. Comparative analyses revealed an open, but approaching closed, pan‐genome. The pan‐genome analysis recovered 4064 genes, with a core genome containing 3306 genes. Phylogenetic analysis of R. salmoninarum showed high genomic homogeneity, apart from one isolate obtained from Salmo trutta in Norway. All genomes presented the 57‐kDa protein (p57). Strain ATCC 33209 and the Chilean isolates H‐2 and DJ2R presented two copies of the msa gene, while the remaining isolates had one copy. The pan‐genome analysis further identified differences in the number of copies and length of the signalling peptide for p57, the principal virulence factor reported for this bacterium. This heterogeneity could be associated with the secretion levels of p57, potentially influencing virulence. Additionally identified were numerous common genes related to iron uptake, the stress response and regulation, and cell signalling—all of which constitute the pathogenic repertoire of R. salmoninarum. This investigation provides information that is applicable in future studies for identifying therapeutic targets and/or for designing new strategies (e.g., vaccines) to prevent BKD infections in salmon farming.

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Aerobic Gram-Positive Rods and Cocci

Cited by 11 publications

References 307 publications

Transcriptomic Profiling of the Adaptive and Innate Immune Responses of Atlantic Salmon to Renibacterium salmoninarum Infection

Transcriptomic Profiling of the Adaptive and Innate Immune Responses of Atlantic Salmon to Renibacterium salmoninarum Infection

Nutritional immunomodulation of Atlantic salmon response to Renibacterium salmoninarum bacterin

Comparative pan‐genomic analysis of 51 Renibacterium salmoninarum indicates heterogeneity in the principal virulence factor, the 57 kDa protein

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