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Annals of the New York Academy of... Mar 2021High-throughput genomic sequencing has helped to reveal the plasmidome of Aeromonas salmonicida. This literature review provides an overview of A. salmonicida's rich... (Review)
Review
High-throughput genomic sequencing has helped to reveal the plasmidome of Aeromonas salmonicida. This literature review provides an overview of A. salmonicida's rich plasmidome by presenting all the plasmids identified so far, addressing their biological importance and the functional links between them. The plasmids of A. salmonicida, especially those bearing antibiotic resistance genes, can provide clues about interactions of this species with other pathogens (animals and humans), as is the case for pRAS3-3432 and Chlamydia suis or pSN254b and Salmonella enterica. In addition to antibiotic resistance, plasmids play an important role in the virulence of A. salmonicida, particularly for the subspecies salmonicida and the plasmid pAsa5, which carries genes for the type-three secretion system, a virulence factor essential for the bacterium. The A. salmonicida plasmidome also has many cryptic plasmids with no known biological function, but which can be used for the acquisition of new genetic elements. Striking examples are pAsa7 and pAsaXII that provide, respectively, resistance to chloramphenicol and formaldehyde and are derivatives of cryptic pAsa2.
Topics: Aeromonas salmonicida; Animals; Drug Resistance, Microbial; Evolution, Molecular; Genetic Variation; Genome, Bacterial; Humans; Plasmids
PubMed: 33040386
DOI: 10.1111/nyas.14503 -
Diseases of Aquatic Organisms Jun 2016Aeromonas salmonicida is the oldest known infectious agent to be linked to fish disease and constitutes a major bacterial pathogen of fish, in particular of salmonids.... (Review)
Review
Aeromonas salmonicida is the oldest known infectious agent to be linked to fish disease and constitutes a major bacterial pathogen of fish, in particular of salmonids. This bacterium can be found almost worldwide in both marine and freshwater environments and has been divided into several sub-species. In this review, we present the most recent developments concerning our understanding of this pathogen, including how the characterization of new isolates from non-salmonid hosts suggests a more nuanced picture of the importance of the so‑called 'atypical isolates'. We also describe the clinical presentation regarding the infection across several fish species and discuss what is known about the virulence of A. salmonicida and, in particular, the role that the type 3 secretion system might play in suppressing the immune response of its hosts. Finally, isolates have displayed varied levels of antibiotic resistance. Hence, we review a number of solutions that have been developed both to prevent outbreaks and to treat them once they occur, including the application of pre- and probiotic supplements.
Topics: Aeromonas salmonicida; Animals; Fish Diseases; Fishes; Furunculosis; Gram-Negative Bacterial Infections
PubMed: 27304870
DOI: 10.3354/dao03006 -
Microbial Biotechnology Sep 2014Aeromonas salmonicida subsp. salmonicida is an important pathogen in salmonid aquaculture and is responsible for the typical furunculosis. The type-three secretion... (Review)
Review
Aeromonas salmonicida subsp. salmonicida is an important pathogen in salmonid aquaculture and is responsible for the typical furunculosis. The type-three secretion system (T3SS) is a major virulence system. In this work, we review structure and function of this highly sophisticated nanosyringe in A. salmonicida. Based on the literature as well as personal experimental observations, we document the genetic (re)organization, expression regulation, anatomy, putative functional origin and roles in the infectious process of this T3SS. We propose a model of pathogenesis where A. salmonicida induces a temporary immunosuppression state in fish in order to acquire free access to host tissues. Finally, we highlight putative important therapeutic and vaccine strategies to prevent furunculosis of salmonid fish.
Topics: Aeromonas salmonicida; Animals; Bacterial Infections; Bacterial Secretion Systems; Fish Diseases; Gene Expression Regulation, Bacterial; Gene Order; Immune Evasion; Immune Tolerance; Macromolecular Substances; Salmonidae; Virulence Factors
PubMed: 24119189
DOI: 10.1111/1751-7915.12091 -
Journal of Microbiology and... Oct 2020The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the... (Review)
Review
The emergence and spread of antimicrobial resistance in pathogenic bacteria of fish and shellfish have caused serious concerns in the aquaculture industry, owing to the potential health risks to humans and animals. Among these bacteria, , which is one of the most important primary pathogens in salmonids, is responsible for significant economic losses in the global aquaculture industry, especially in salmonid farming because of its severe infectivity and acquisition of antimicrobial resistance. Therefore, interest in the use of alternative approaches to prevent and control infections has increased in recent years, and several applications of bacteriophages (phages) have provided promising results. For several decades, and phages infecting this fish pathogen have been thoroughly investigated in various research areas including aquaculture. The general overview of phage usage to control bacterial diseases in aquaculture, including the general advantages of this strategy, has been clearly described in previous reviews. Therefore, this review specifically focuses on providing insights into the phages infecting , from basic research to biotechnological application in aquaculture, as well as recent advances in the study of .
Topics: Aeromonas salmonicida; Animals; Aquaculture; Bacterial Infections; Bacteriophages; Fish Diseases; Fishes
PubMed: 32807762
DOI: 10.4014/jmb.2005.05040 -
Journal of Fish Diseases Nov 2019Aeromonas salmonicida subsp. salmonicida (hereafter A. salmonicida) is the aetiological agent of furunculosis in marine and freshwater fish. Once A. salmonicida invade...
Aeromonas salmonicida subsp. salmonicida (hereafter A. salmonicida) is the aetiological agent of furunculosis in marine and freshwater fish. Once A. salmonicida invade the fish host through skin, gut or gills, it spreads and colonizes the head kidney, liver, spleen and brain. A. salmonicida infects leucocytes and exhibits an extracellular phase in the blood of the host; however, it is unknown whether A. salmonicida have an intraerythrocytic phase. Here, we evaluate whether A. salmonicida infects Atlantic salmon (Salmo salar) erythrocytes in vitro and in vivo. A. salmonicida did not kill primary S. salar erythrocytes, even in the presence of high bacterial loads, but A. salmonicida invaded the S. salar erythrocytes in the absence of evident haemolysis. Naïve Atlantic salmon smolts intraperitoneally infected with A. salmonicida showed bacteraemia 5 days post-infection and the presence of intraerythrocytic A. salmonicida. Our results reveal a novel intraerythrocytic phase during A. salmonicida infection.
Topics: Aeromonas salmonicida; Animals; Erythrocytes; Furunculosis; Gram-Negative Bacterial Infections; Salmo salar
PubMed: 31456227
DOI: 10.1111/jfd.13077 -
FEMS Microbiology Letters Aug 2022Worldwide, Aeromonas salmonicida is a major bacterial pathogen of fish in both marine and freshwater environments. Despite psychrophilic growth being common for this...
Worldwide, Aeromonas salmonicida is a major bacterial pathogen of fish in both marine and freshwater environments. Despite psychrophilic growth being common for this species, the number of characterized mesophilic strains is increasing. Thus, this species may serve as a model for the study of intraspecies lifestyle diversity. Although bacteria are preyed upon by protozoan predators, their interaction inside or outside the phagocytic pathway of the predator can provide several advantages to the bacteria. To correlate intraspecies diversity with predation outcome, we studied the fate of psychrophilic and mesophilic strains of A. salmonicida cocultured with the ciliate Tetrahymena pyriformis. A total of three types of outcome were observed: digestion, resistance to phagocytosis, and pathogenicity. The psychrophilic strains are fully digested by the ciliate. In contrast, the mesophilic A. salmonicida subsp. pectinolytica strain is pathogenic to the ciliate. All the other mesophilic strains display mechanisms to resist phagocytosis and/or digestion, which allow them to survive ciliate predation. In some cases, passage through the phagocytic pathway resulted in a few mesophilic A. salmonicida being packaged inside fecal pellets. This study sheds light on the great phenotypic diversity observed in the complex range of mechanisms used by A. salmonicida to confront a predator.
Topics: Aeromonas; Aeromonas salmonicida; Animals; Fish Diseases; Fishes; Tetrahymena pyriformis; Virulence
PubMed: 35883218
DOI: 10.1093/femsle/fnac067 -
Genome May 2023All the 36 known species to date of the genus are mesophilic except the species , which includes both psychrophilic and mesophilic subspecies. For 20 years, more and...
All the 36 known species to date of the genus are mesophilic except the species , which includes both psychrophilic and mesophilic subspecies. For 20 years, more and more mesophilic strains have been discovered. Only subsp. has officially been classified as a mesophilic subspecies. Most mesophiles have been isolated in hot countries. We present, for the first time, the characterization of two new mesophilic isolates from Quebec (Canada). Phenotypic and genomic characterizations were carried out on these strains, isolated from dead fish from a fish farm. Isolates 19-K304 and 19-K308 are clearly mesophiles, virulent to the amoeba , a surrogate host, and close to strain Y577, isolated in India. To our knowledge, this is the first time that mesophilic strains isolated from different countries are so similar. The major difference between the isolates is the presence of plasmid pY47-3, a cryptic plasmid that sometimes presents in mesophilic strains. More importantly, our extensive phylogenetic analysis reveals two well-defined clades of mesophilic strains with psychrophiles associated with one of these clades. This helps to have a better understanding of the evolution of this species and the apparition of psychrophilic subspecies.
Topics: Animals; Aeromonas salmonicida; Phylogeny; Dictyostelium; Canada; Cluster Analysis
PubMed: 36780641
DOI: 10.1139/gen-2022-0086 -
Fish & Shellfish Immunology Sep 2020Effective vaccine programs against Aeromonas salmonicida have been identified as a high priority area for the sablefish (Anoplopoma fimbria) aquaculture. In this study,...
Effective vaccine programs against Aeromonas salmonicida have been identified as a high priority area for the sablefish (Anoplopoma fimbria) aquaculture. In this study, we established an A. salmonicida infection model in sablefish to evaluate the efficacy of commercial vaccines and an autogenous vaccine preparation. Groups of 40 fish were intraperitoneally (ip) injected with different doses of A. salmonicida J410 isolated from infected sablefish to calculate the median lethal dose (LD). Samples of blood, head kidney, spleen, brain, and liver were also collected at different time points to determine the infection kinetics. The LD was estimated as ~3 × 10 CFU/dose. To evaluate the immune protection provided by an autogenous vaccine and two commercial vaccines in a common garden experimental design, 140 fish were PIT-tagged, vaccinated and distributed equally into 4 tanks (35 fish for each group, including a control group). Blood samples were taken every 2 weeks to evaluate IgM titers. At 10 weeks post-immunization, all groups were ip challenged with 100 times the calculated LD for A. salmonicida J410. A. salmonicida was detected after 5 days post-infection (dpi) in all collected tissues. At 30 days post-challenge the relative percentage survival (RPS) with respect to the control group was calculated for each vaccine. The RPS for the bacterin mix was 65.22%, for Forte Micro 4® vaccine was 56.52% and for Alpha Ject Micro 4® was 30.43%, and these RPS values were reflected by A. salmonicida tissue colonization levels at 10 days post-challenge. Total IgM titers peaked at 6-8 weeks post-immunization, where the autogenous vaccine group showed the highest IgM titers and these values were consistent with the RPS data. Also, we determined that the A. salmonicida A-layer binds to immunoglobulins F(ab)' in a non-specific fashion, interfering with immune assays and potentially vaccine efficacy. Our results indicate that vaccine design influences sablefish immunity and provide a guide for future sablefish vaccine programs.
Topics: Aeromonas salmonicida; Animals; Fish Diseases; Fishes; Furunculosis; Gram-Negative Bacterial Infections; Immunity, Innate; Injections, Intraperitoneal; Perciformes; Random Allocation; Vaccination
PubMed: 32592927
DOI: 10.1016/j.fsi.2020.06.005 -
Frontiers in Immunology 2019In contrast to other teleosts, Atlantic cod () has an expanded repertoire of MHC-I and TLR components, but lacks the MHC-II, the invariant chain/CD74, and CD4 T cell...
In contrast to other teleosts, Atlantic cod () has an expanded repertoire of MHC-I and TLR components, but lacks the MHC-II, the invariant chain/CD74, and CD4 T cell response, essential for production of antibodies and prevention of bacterial infectious diseases. The mechanisms by which fight bacterial infections are not well understood. subsp. is a recurrent pathogen in cultured and wild fish, and has been reported in Atlantic cod. Macrophages are some of the first responders to bacterial infection and the link between innate and adaptive immune response. Here, we evaluated the viability, reactive oxygen species (ROS) production, cell morphology, and gene expression of cod primary macrophages in response to infection. We found that infects cod primary macrophages without killing the cod cells. Likewise, infected Atlantic cod macrophages up-regulated key genes involved in the inflammatory response (e.g., β and ) and bacterial recognition (e.g., ). Nevertheless, our results showed a down-regulation of genes related to antimicrobial peptide and ROS production, suggesting that utilizes its virulence mechanisms to control and prevent macrophage anti-bacterial activity. Our results also indicate that Atlantic cod has a basal ROS production in non-infected cells, and this was not increased after contact with . Transmission electron microscopy results showed that was able to infect the macrophages in a high number, and release outer membrane vesicles (OMV) during intracellular infection. These results suggest that Atlantic cod macrophage innate immunity is able to detect and trigger an anti-inflammatory response, however controls the cell immune response to prevent bacterial clearance, during early infection.
Topics: Aeromonas salmonicida; Animals; Biomarkers; Cell Survival; Fish Diseases; Gadus morhua; Gene Expression Regulation; Gram-Negative Bacterial Infections; Host-Pathogen Interactions; Macrophages; Reactive Oxygen Species
PubMed: 31231379
DOI: 10.3389/fimmu.2019.01237 -
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