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Virulence Dec 2023Active flavins derived from riboflavin (vitamin B) are essential for life. Bacteria biosynthesize riboflavin or scavenge it through uptake systems, and both mechanisms...
Active flavins derived from riboflavin (vitamin B) are essential for life. Bacteria biosynthesize riboflavin or scavenge it through uptake systems, and both mechanisms may be present. Because of riboflavin's critical importance, the redundancy of riboflavin biosynthetic pathway (RBP) genes might be present. , the aetiological agent of furunculosis, is a pathogen of freshwater and marine fish, and its riboflavin pathways have not been studied. This study characterized the riboflavin provision pathways. Homology search and transcriptional orchestration analysis showed that has a main riboflavin biosynthetic operon that includes , , , and genes. Outside the main operon, putative duplicated genes , and , and a riboflavin importer encoding gene, were found. Monocistronic mRNA , and encode for their corresponding functional riboflavin biosynthetic enzyme. While the product of conserved the RibB function, it lacked the RibA function. Likewise, encodes a functional riboflavin importer. Transcriptomics analysis indicated that external riboflavin affected the expression of a relatively small number of genes, including a few involved in iron metabolism. was downregulated in response to external riboflavin, suggesting negative feedback. Deletion of , and showed that these genes are required for riboflavin biosynthesis and virulence in Atlantic lumpfish (). riboflavin auxotrophic attenuated mutants conferred low protection to lumpfish against virulent . Overall, has multiple riboflavin endowment forms, and duplicated riboflavin provision genes are critical for infection.
Topics: Animals; Aeromonas salmonicida; Gene Duplication; Virulence; Riboflavin; Fishes; Fish Diseases
PubMed: 36895132
DOI: 10.1080/21505594.2023.2187025 -
Frontiers in Microbiology 2017Furunculosis, a serious infection caused by the bacterium subsp. is common in sea-reared rainbow trout production in Denmark. Developing an effective control strategy...
Furunculosis, a serious infection caused by the bacterium subsp. is common in sea-reared rainbow trout production in Denmark. Developing an effective control strategy requires knowledge of the epidemiology, as well as the genomic and virulent variability of the Danish subsp. isolates. To obtain this, the genomes of 101 subsp. , including 99 Danish isolates, one Scottish strain and the type strain NCIMB 1102, were sequenced using the Illumina HiSeq platform. Isolates were assembled, examined for presence of plasmids, virulence and iron acquisition proteins, genomic islands, and antibiotic resistance genes. Single Nucleotide Polymorphisms were aligned and subjected to Bayesian temporal phylogenetic and maximum likelihood tree reconstruction using the published genome of subsp. A449 as reference. Bayesian temporal phylogenetic reconstruction suggests that four major introductions of subsp. into Denmark have occurred. The introductions correlate with the freshwater and subsequent seawater expansion of rainbow trout production. Initial transmission of the bacterium could have been from seawater to freshwater or vice versa, and most minor clades include a mixture of strains from different fresh- and seawater farms. Genomic variation of subsp. mostly appeared to be associated with their plasmids and plasmid encoded virulence factors. Nine subsp. isolates harbored worldwide known antibiotic resistance genes against several antibiotics and there is an indication that 33% of the isolates contained the genomic island AsaGEI1b. These findings not only support the usefulness of whole genome sequencing for genetic studies of homogeneous bacteria in general, but provide novel information about the Danish subsp. population, with implications for vaccine development in efforts to better protect Danish rainbow trout in the future.
PubMed: 29259599
DOI: 10.3389/fmicb.2017.02411 -
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 -
Indian Journal of Microbiology Jun 2019In this study, subsp. was isolated, identified by 16S RNA sequencing and its potential lytic phage (ASP-1) was isolated and characterized. The bacterium was positive...
In this study, subsp. was isolated, identified by 16S RNA sequencing and its potential lytic phage (ASP-1) was isolated and characterized. The bacterium was positive for virulence genes (, , , , , and ) and phenotypic parameters (haemolysis, slime production, lipase activity, DNase test, gelatinase activity and protease activity) were tested. The bacterium was resistant to 27%, intermediate resistant to 14% and susceptible to 59% of tested common antibiotics. Transmission electron microscopy analysis revealed that lytic ASP-1 belongs to the family. The isolated phage was more specific against subsp. (efficiency of plating index = 1), but also had infectivity to lab strain 1. The bacteriolytic effect of ASP-1 was tested at early exponential phase culture of subsp. , and bacteria growth was apparently decreased with time and MOI dependent manner. One-step growth of ASP-1 showed approximately 30 min of latent period, 16 PFU/infected cells of burst size and 40 min of rise period. The adsorption rate was determined as 3.61 × 10 PFU mL min for 3 min, and rate decreased with time. The ASP-1 genome size was estimated to be approximately 55-60 kD. The phage was stable over wide-range of temperatures, pH and salinity, thus could withstand at severe environmental conditions, indicating that ASP-1 has a potential to develop as an alternative antibiotic to use in ornamental and aquaculture industry.
PubMed: 31031430
DOI: 10.1007/s12088-019-00782-5 -
Schweizer Archiv Fur Tierheilkunde Jun 2018
Topics: Aeromonas salmonicida; Animals; Fish Diseases; Furunculosis; Gram-Negative Bacterial Infections; Oncorhynchus mykiss; Skin Diseases, Bacterial
PubMed: 29905164
DOI: 10.17236/sat00167 -
Frontiers in Microbiology 2015Furunculosis, which is caused by Aeromonas salmonicida subsp. salmonicida, is a major salmonid disease in fish farms worldwide. Several plasmids found in this bacterium...
Furunculosis, which is caused by Aeromonas salmonicida subsp. salmonicida, is a major salmonid disease in fish farms worldwide. Several plasmids found in this bacterium confer phenotypes such drug resistance and virulence. Small plasmids (pAsa1, pAsa2, pAsa3, and pAsal1) related to ColE1- and ColE2-type replicons are usually present in its normal plasmidome. In the present study, with the objective to investigate if these plasmids display particularities related to the origin of the isolates bearing them, a total of 153 isolates, including 78 new and 75 previously described, were analyzed for the presence of small plasmids by PCR and DNA restriction fragment profiling. A geographical dichotomy between Canadian and European isolates for their propensity to do not have pAsa3 or pAsal1 was found. In addition, the genotyping analysis led to the identification of two European isolates harboring an unusual pAsal1. An investigation by next-generation sequencing (NGS) of these two isolates shed light on two pAsal1 variants (pAsal1C and pAsal1D). As with pAsal1B, another pAsal1 variant previously described, these two new variants bore a second insertion sequence (ISAS5) in addition to the usual ISAS11. The characterization of these variants suggested that they could predominate over the wild-type pAsal1 in stressful conditions such as growth at temperatures of 25°C and above. To obtain a comprehensive portrait of the mutational pressure on small plasmids, 26 isolates whose DNA had been sequenced by NGS were investigated. pAsa3 and pAsal1 were more prone to mutations than pAsa1 and pAsa2, especially in the mobA gene, which encodes a relaxase and a primase. Lastly, the average copy number of each plasmid per cell was assessed using raw sequencing data. A clear trend with respect to the relative proportion per cell of each plasmid was identified. Our large-scale study revealed a geographical dichotomy in small plasmid repertoire in addition to a clear trend for pAsa3 and pAsal1 to be more frequently altered. Moreover, we present the discovery of two new variants of pAsal1: pAsal1C and pAsal1D.
PubMed: 26635745
DOI: 10.3389/fmicb.2015.01274 -
Bacteriophage 2014Bacteriophages have been proposed as an alternative to antibiotic usage and several studies on their application in aquaculture have been reported. This review... (Review)
Review
Bacteriophages have been proposed as an alternative to antibiotic usage and several studies on their application in aquaculture have been reported. This review highlights progress to date on phage therapies for the following fish and shellfish diseases and associated pathogens: hemorrhagic septicemia (Aeromonas hydrophila) in loaches, furunculosis (Aeromonas salmonicida) in trout and salmon, edwardsiellosis (Edwardsiella tarda) in eel, columnaris disease (Flavobacterium columnare) in catfish, rainbow trout fry syndrome or cold water disease (Flavobacterium psychrophilum) in trout and salmon, lactococcosis (Lactococcus spp.) in yellowtail, ulcerative skin lesions (Pseudomonas aeruginosa) in freshwater catfish, bacterial hemorrhagic ascites disease (Pseudomonas plecoglossicida) in ayu fish, streptococcosis (Streptococcus iniae) in flounder, and luminescent vibriosis (Vibrio harveyi) in shrimp. Information is reviewed on phage specificity, host resistance, routes of administration, and dosing of fish and shellfish. Limitations in phage research are described and recommended guidelines are provided for conducting future phage studies involving fish and shellfish.
PubMed: 26713223
DOI: 10.4161/21597081.2014.975540 -
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 -
Animals : An Open Access Journal From... Sep 2021The aim of the study was to isolate and identify species belonging to the genus and evaluate the antimicrobial resistance and virulence patterns of isolates colonizing...
The aim of the study was to isolate and identify species belonging to the genus and evaluate the antimicrobial resistance and virulence patterns of isolates colonizing European pond turtles () from natural environment of Eastern Poland. In total, 74 turtles and 15 samples of water from their natural environment were examined. More than 40 strains were isolated and identified: ( = 1), ( = 13), ( = 2), ( = 3), and ( = 23). The highest incidence of resistance was noted for ampicillin (100%) and sulfamethoxazole (62.0%), followed by erythromycin and colistin (both 40.5%). Moreover, eight strains were intermediately resistant to meropenem (19%). Most isolates were found to possess more than one virulence gene among A, , and . We showed that the population of free-living European pond turtles was highly colonized by spp. Such strains may be an infectious agent not only for the population of turtles but also for other species of animals inhabiting their natural environment. Moreover, the undesirable properties of water quality caused by the presence of drug-resistant aeromonads could have a negative impact on human health.
PubMed: 34679794
DOI: 10.3390/ani11102772 -
Microorganisms Jan 2022The bacterium has long been known to be one of the most feared pathogens in fish farming. However, the more we discover about this bacterial species, the more we...
The bacterium has long been known to be one of the most feared pathogens in fish farming. However, the more we discover about this bacterial species, the more we question whether it is really exclusively an aquatic pathogen. In recent years, it has become obvious that this bacterial species includes a myriad of strains with various lifestyle and ecological niches, including the well-known strict psychrophiles, the first bacteria known of the species, and the newly described mesophilic strains. The mesophiles are able to grow at low temperatures, but even better at temperatures of approximately 37 °C, which strict psychrophiles cannot do. In this perspective article, we address some aspects surrounding this dual lifestyle in , including the impact of mobile genetic elements, and how future research around this bacterial species may focus on the psychrophilic/mesophilic dichotomy, which makes an increasingly interesting and relevant model for the study of speciation.
PubMed: 35208695
DOI: 10.3390/microorganisms10020240