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Microorganisms Oct 2023is the causative agent of septicemia in fish, and it is associated with significant economic losses in the aquaculture industry. While piscine infections are mainly...
is the causative agent of septicemia in fish, and it is associated with significant economic losses in the aquaculture industry. While piscine infections are mainly treated with antibiotics, the emergence of resistance in bacterial populations requires the development of alternative methods of treatment. The use of phages can be one of them. A novel jumbo phage, AerS_266, was isolated and characterized. This phage infects only mesophilic strains and demonstrates a slow lytic life cycle. Its genome contains 243,674 bp and 253 putative genes: 84 encode proteins with predicted functions, and 3 correspond to tRNAs. Genes encoding two multisubunit RNA polymerases, chimallin and PhuZ, were identified, and AerS_266 was thus defined as a phiKZ-like phage. While similar phages with genomes >200 kb specific to and have been previously described, AerS_266 is the first phiKZ-like phage found to infect .
PubMed: 38004661
DOI: 10.3390/microorganisms11112649 -
Virulence Dec 2022Carbohydrates can both protect against infection and act as targets promoting infection. Mucins are major components of the slimy mucus layer covering the fish...
Carbohydrates can both protect against infection and act as targets promoting infection. Mucins are major components of the slimy mucus layer covering the fish epithelia. Mucins can act as decoys for intimate pathogen interaction with the host afforded by binding to glycosphingolipids in the host cell membrane. We isolated and characterized glycosphingolipids from Atlantic salmon skin, gill, stomach, pyloric caeca, and intestine. We characterized the glycosphingolipids using liquid chromatography - mass spectrometry and tandem mass spectrometry and the glycan repertoire was compared with the glycan repertoire of mucins from the same epithelia. We also investigated binding using chromatogram and microtiter well based binding assays. We identified 29 glycosphingolipids. All detected acid glycans were of the ganglio-series (unless shorter) and showed a high degree of polysialylation. The non-acid glycans were mostly composed of the neolacto, globo, and ganglio core structures. The glycosphingolipid repertoire differed between epithelia and the proportion of the terminal moieties of the glycosphingolipids did not reflect the terminal moieties on the mucins from the same epithelia. did not bind the Atlantic salmon glycosphingolipids. Instead, we identified that binding to sialic acid occurred to α2-6 Neu5Ac but not to α2-3 Neu5Ac. α2-6 Neu5Ac was present on mucins whereas mainly α2-3 Neu5Ac was found on the glycosphingolipids, explaining the difference in binding ability between these host glycoconjugates. ability to bind to Atlantic salmon mucins, but not the glycosphingolipids, is likely part of the host defence against this pathogen.
Topics: Aeromonas salmonicida; Animals; Cecum; Gills; Glycosphingolipids; Intestines; Mucins; N-Acetylneuraminic Acid; Polysaccharides; Stomach; Tandem Mass Spectrometry
PubMed: 36205522
DOI: 10.1080/21505594.2022.2132056 -
FEMS Microbiology Reviews Jun 1997Although S-layers are being increasingly identified on Bacteria and Archaea, it is enigmatic that in most cases S-layer function continues to elude us. In a few... (Comparative Study)
Comparative Study
Although S-layers are being increasingly identified on Bacteria and Archaea, it is enigmatic that in most cases S-layer function continues to elude us. In a few instances, S-layers have been shown to be virulence factors on pathogens (e.g. Campylobacter fetus ssp. fetus and Aeromonas salmonicida), protective against Bdellovibrio, a depository for surface-exposed enzymes (e.g. Bacillus stearothermophilus), shape-determining agents (e.g. Thermoproteus tenax) and nucleation factors for fine-grain mineral development (e.g. Synechococcus GL 24). Yet, for the vast majority of S-layered bacteria, the natural function of these crystalline arrays continues to be evasive. The following review up-dates the functional basis of S-layers and describes such diverse topics as the effect of S-layers on the Gram stain, bacteriophage adsorption in lactobacilli, phagocytosis by human polymorphonuclear leukocytes, the adhesion of a high-molecular-mass amylase, outer membrane porosity, and the secretion of extracellular enzymes of Thermoanaerobacterium. In addition, the functional aspect of calcium on the Caulobacter S-layer is explained.
Topics: Abortion, Veterinary; Amino Acid Sequence; Animals; Archaea; Bacteria; Bacterial Adhesion; Bacterial Outer Membrane Proteins; Bacterial Physiological Phenomena; Campylobacter Infections; Cell Membrane; Cell Wall; Crystallization; Eukaryota; Female; Humans; Molecular Sequence Data; Phagocytosis; Pregnancy; Sequence Alignment; Sequence Homology, Amino Acid; Sheep; Sheep Diseases; Species Specificity; Virulence
PubMed: 9276929
DOI: 10.1111/j.1574-6976.1997.tb00305.x -
Antibiotics (Basel, Switzerland) Aug 2022subsp. is a pathogenic bacterium responsible for furunculosis in salmonids. Following an outbreak of furunculosis, the infection can be treated with antibiotics, but...
subsp. is a pathogenic bacterium responsible for furunculosis in salmonids. Following an outbreak of furunculosis, the infection can be treated with antibiotics, but it is common to observe ineffective treatment due to antibiotic resistance. This bacterium has a wide variety of plasmids responsible for this resistance. Among them, pRAS3 carries a tetracycline resistance gene. Several variants of this plasmid have been discovered over the years (pRAS3-3432 and pRAS3.1 to 3.4). During the present study, two new variants of the plasmid pRAS3 were identified (pRAS3.5 and pRAS3-3759) in strains of subsp. . Plasmid pRAS3-3759, which has been found in many strains from the same region over the past three years, has an additional genetic element identical to one found in pRAS3-3432. This genetic element was also found in , a swine pathogen. In this study, we analyzed the bacteria's resistance to tetracycline, the number of copies of the plasmids, and the growth of the strains that carry five of the pRAS3 variants (pRAS3.3 to 3.5, pRAS3-3432, and pRAS3-3759). The results show no particular trend despite the differences between the plasmids, except for the resistance to tetracycline when analyzed in an isogenic background. Blast analysis also revealed the presence of pRAS3 plasmids in other bacterial species, which suggests that this plasmid family has widely spread. This study once again highlights the ability of subsp. to adapt to furunculosis antibiotic treatments, and the still-growing family of pRAS3 plasmids.
PubMed: 36009916
DOI: 10.3390/antibiotics11081047 -
International Journal of Molecular... Jan 2022Rainbow trout () serves as one of the most important commercial fish with an annual production of around 800,000 tonnes. However, infectious diseases, such as...
Rainbow trout () serves as one of the most important commercial fish with an annual production of around 800,000 tonnes. However, infectious diseases, such as furunculosis caused by infection, results in great economic loss in trout culture. The brain and kidney are two important organs associated with "sickness behaviors" and immunomodulation in response to disease. Therefore, we worked with 60 trout and investigated transcriptional responses and enrichment pathways between healthy and infected trout. We observed that furunculosis resulted in the activation of toll-like receptors with neuroinflammation and neural dysfunction in the brain, which might cause the "sickness behaviors" of infected trout including anorexia and lethargy. We also showed the salmonid-specific whole genome duplication contributed to duplicated colony stimulating factor 1 () paralogs, which play an important role in modulating brain immunomodulation. Enrichment analyses of kidneys showed up-regulated immunomodulation and down-regulated neural functions, suggesting an immune-neural interaction between the brain and kidney. Moreover, the kidney endocrine network was activated in response to infection, further convincing the communications between endocrine and immune systems in regulating internal homeostasis. Our study provided a foundation for pathophysiological responses of the brain and kidney in response to furunculosis and potentially offered a reference for generating disease-resistant trout strains.
Topics: Aeromonas salmonicida; Animals; Brain; Fish Diseases; Fish Proteins; Furunculosis; Gene Expression; Gene Expression Profiling; Gram-Negative Bacterial Infections; Kidney; Oncorhynchus mykiss; Transcriptome
PubMed: 35163263
DOI: 10.3390/ijms23031340 -
Microorganisms Dec 2023Furunculosis, caused by , poses a significant threat to both salmonid and non-salmonid fish in diverse aquatic environments. This study explores the genomic intricacies...
Furunculosis, caused by , poses a significant threat to both salmonid and non-salmonid fish in diverse aquatic environments. This study explores the genomic intricacies of re-emergent outbreaks in Atlantic salmon (). Previous clinical cases have exhibited pathological characteristics, such as periorbital hemorrhages and gastrointestinal abnormalities. Genomic sequencing of three Chilean isolates (ASA04, ASA05, and CIBA_5017) and 25 previously described genomes determined the pan-genome, phylogenomics, insertion sequences, and restriction-modification systems. Unique gene families have contributed to an improved understanding of the psychrophilic and mesophilic clades, while phylogenomic analysis has been used to identify mesophilic and psychrophilic strains, thereby further differentiating between typical and atypical psychrophilic isolates. Diverse insertion sequences and restriction-modification patterns have highlighted genomic structural differences, and virulence factor predictions can emphasize exotoxin disparities, especially between psychrophilic and mesophilic strains. Thus, a novel plasmid was characterized which emphasized the role of plasmids in virulence and antibiotic resistance. The analysis of antibiotic resistance factors revealed resistance against various drug classes in Chilean strains. Overall, this study elucidates the genomic dynamics of re-emergent and provides novel insights into their virulence, antibiotic resistance, and population structure.
PubMed: 38257891
DOI: 10.3390/microorganisms12010064 -
Viruses Nov 2021Aquaculture is a rapidly growing food production sector. Fish farmers are experiencing increasing problems with antibiotic resistance when fighting against pathogenic...
Aquaculture is a rapidly growing food production sector. Fish farmers are experiencing increasing problems with antibiotic resistance when fighting against pathogenic bacteria such as subsp. , the causative agent of furunculosis. Phage therapy may provide an alternative, but effective use must be determined. Here, we studied the inhibition of subsp. strains by five phages (HER98 [44RR2.8t.2], HER110 [65.2], SW69-9, L9-6 and Riv-10) used individually or as combinations of two to five phages. A particular combination of four phages (HER98 [44RR2.8t.2], SW69-9, Riv-10, and HER110 [65.2]) was found to be the most effective when used at an initial multiplicity of infection (MOI) of 1 against the subsp. strain 01-B526. The same phage cocktail is effective against other strains except those bearing a prophage (named Prophage 3), which is present in 2/3 of the strains from the province of Quebec. To confirm the impact of this prophage, we tested the effectiveness of the same cocktail on strains that were either cured or lysogenized with Prophage 3. While the parental strains were sensitive to the phage cocktail, the lysogenized ones were much less sensitive. These data indicate that the prophage content of subsp. can affect the efficacy of a cocktail of virulent phages for phage therapy purposes.
Topics: Aeromonas; Animals; Aquaculture; Bacteriophages; Furunculosis; Genomic Islands; Host Specificity; Lysogeny; Phage Therapy; Prophages
PubMed: 34835047
DOI: 10.3390/v13112241 -
Frontiers in Immunology 2022(sea lice) and bacterial co-infection threatens wild and farmed Atlantic salmon performance and welfare. In the present study, pre-adult -infected and non-infected...
(sea lice) and bacterial co-infection threatens wild and farmed Atlantic salmon performance and welfare. In the present study, pre-adult -infected and non-infected salmon were intraperitoneally injected with either formalin-killed bacterin (ASAL) or phosphate-buffered saline (PBS). Dorsal skin samples from each injection/infection group (PBS/no lice, PBS/lice, ASAL/no lice, and ASAL/lice) were collected at 24 h post-injection and used for transcriptome profiling using a 44K salmonid microarray platform. Microarray results showed no clear inflammation gene expression signatures and revealed extensive gene repression effects by pre-adult lice (2,189 down and 345 up-regulated probes) in the PBS-injected salmon (PBS/lice . PBS/no lice), which involved basic cellular (e.g., RNA and protein metabolism) processes. Lice repressive effects were not observed within the group of ASAL-injected salmon (ASAL/lice . ASAL/no lice); on the contrary, the observed skin transcriptome changes -albeit of lesser magnitude (82 up and 1 down-regulated probes)- suggested the activation in key immune and wound healing processes (e.g., neutrophil degranulation, keratinocyte differentiation). The molecular skin response to ASAL was more intense in the lice-infected (ASAL/lice . PBS/lice; 272 up and 11 down-regulated probes) than in the non-infected fish (ASAL/no lice . PBS/no lice; 27 up-regulated probes). Regardless of lice infection, the skin's response to ASAL was characterized by the putative activation of both antibacterial and wound healing pathways. The transcriptomic changes prompted by ASAL+lice co-stimulation (ASAL/lice . PBS/no lice; 1878 up and 3120 down-regulated probes) confirmed partial mitigation of lice repressive effects on fundamental cellular processes and the activation of pathways involved in innate (e.g., neutrophil degranulation) and adaptive immunity (e.g., antibody formation), as well as endothelial cell migration. The qPCR analyses evidenced immune-relevant genes co-stimulated by ASAL and lice in an additive (e.g., , ) and synergistic (e.g., , ) manner. These results provided insight on the physiological response of the skin of -infected salmon 24 h after ASAL stimulation, which revealed immunostimulatory properties by the bacterin with potential applications in anti-lice treatments for aquaculture. As a simulated co-infection model, the present study also serves as a source of candidate gene biomarkers for sea lice and bacterial co-infection.
Topics: Aeromonas salmonicida; Animals; Bacterial Vaccines; Coinfection; Copepoda; Fish Diseases; Formaldehyde; Phthiraptera; Salmo salar; Transcriptome
PubMed: 35401509
DOI: 10.3389/fimmu.2022.804987 -
Proteome Science Oct 2013Aeromonas salmonicida subsp. salmonicida, the etiologic agent of furunculosis, is a major pathogen of fisheries worldwide. Despite the identification of several...
BACKGROUND
Aeromonas salmonicida subsp. salmonicida, the etiologic agent of furunculosis, is a major pathogen of fisheries worldwide. Despite the identification of several virulence factors the pathogenesis is still poorly understood. We have used high-throughput proteomics to display the differences between in vitro secretome of A. salmonicida wild-type (wt, hypervirulent, JF5054) and T3SS-deficient (isogenic ΔascV, extremely low-virulent, JF2747) strains in exponential (GP) and stationary (SP) phases of growth.
RESULTS
Among the different experimental conditions we obtained semi-quantitative values for a total of 2136 A. salmonicida proteins. Proteins of specific A. salmonicida species were proportionally less detected than proteins common to the Aeromonas genus or those shared with other Aeromonas species, suggesting that in vitro growth did not induce the expression of these genes. Four detected proteins which are unidentified in the genome of reference strains of A. salmonicida were homologous to components of the conjugative T4SS of A. hydrophila pRA1 plasmid. Polypeptides of three proteins which are specific to the 01-B526 strain were also discovered. In supernatants (SNs), the number of detected proteins was higher in SP (326 for wt vs 329 for mutant) than in GP (275 for wt vs 263 for mutant). In pellets, the number of identified proteins (a total of 1536) was approximately the same between GP and SP. Numerous highly conserved cytoplasmic proteins were present in A. salmonicida SNs (mainly EF-Tu, EF-G, EF-P, EF-Ts, TypA, AlaS, ribosomal proteins, HtpG, DnaK, peptidyl-prolyl cis-trans isomerases, GAPDH, Enolase, FbaA, TpiA, Pgk, TktA, AckA, AcnB, Mdh, AhpC, Tpx, SodB and PNPase), and several evidences support the theory that their extracellular localization was not the result of cell lysis. According to the Cluster of Orthologous Groups classification, 29% of excreted proteins in A. salmonicida SNs were currently poorly characterized.
CONCLUSIONS
In this part of our work we elucidated the whole in vitro exoproteome of hypervirulent A. salmonicida subsp. salmonicida and showed the secretion of several highly conserved cytoplasmic proteins with putative moonlighting functions and roles in virulence. All together, our results offer new information about the pathogenesis of furunculosis and point out potential candidates for vaccine development.
PubMed: 24127837
DOI: 10.1186/1477-5956-11-44 -
Marine Biotechnology (New York, N.Y.) Mar 2022Aeromonas salmonicida is a global fish pathogen. Aeromonas salmonicida subsp. masoucida (ASM) is classified as atypical A. salmonicida and caused huge losses to salmonid...
Comparative Transcriptome Analysis of Spleen Reveals Potential Regulation of Genes and Immune Pathways Following Administration of Aeromonas salmonicida subsp. masoucida Vaccine in Atlantic Salmon (Salmo salar).
Aeromonas salmonicida is a global fish pathogen. Aeromonas salmonicida subsp. masoucida (ASM) is classified as atypical A. salmonicida and caused huge losses to salmonid industry in China. Hence, it is of great significance to develop ASM vaccine and explore its protection mechanism in salmonids. In this regard, we conducted RNA-seq analysis with spleen tissue of Atlantic salmon after ASM vaccination to reveal genes, their expression patterns, and pathways involved in immune protections. In our results, a total of 441.63 million clean reads were obtained, and 389.37 million reads were mapped onto the Atlantic salmon reference genome. In addition, 1125, 2126, 1098, 820, and 1351 genes were significantly up-regulated, and 747, 2626, 818, 254, and 908 genes were significantly down-regulated post-ASM vaccination at 12 h, 24 h, 1 month, 2 months, and 3 months, respectively. Subsequent pathway analysis revealed that many differentially expressed genes (DEGs) following ASM vaccination were involved in cytokine-cytokine receptor interaction (TNFRSF11b, IL-17RA, CCR9, and CXCL11), HTLV-I infection (MR1 and HTLV-1), MAPK signaling pathway (MAPK, IL8, and TNF-α-1), PI3K-Akt signaling pathway (PIK3R3, THBS4, and COL2A1), and TNF signaling pathway (PTGS2, TNFRSF21-l, and CXCL10). Finally, the results of qRT-PCR showed a significant correlation with RNA-seq results, suggesting the reliability of RNA-seq for gene expression analysis. This study provided insights into regulation of gene expression and their involved pathways in Atlantic salmon spleen in responses to vaccine, and set the foundation for further study on the vaccine protective mechanism in Atlantic salmon as well as other teleost species.
Topics: Aeromonas; Aeromonas salmonicida; Animals; Fish Diseases; Gene Expression Profiling; Phosphatidylinositol 3-Kinases; Reproducibility of Results; Salmo salar; Spleen; Vaccines
PubMed: 35084599
DOI: 10.1007/s10126-021-10089-6