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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 -
Pathogens (Basel, Switzerland) Nov 2023We studied the phenotypic and genomic characteristics related to the virulence and antibiotic resistance of two strains, which were co-isolated before an outbreak of...
We studied the phenotypic and genomic characteristics related to the virulence and antibiotic resistance of two strains, which were co-isolated before an outbreak of among diseased seabass on Agathonisi Island, Greece, in April 2015. The first strain, AG2.13.2, is a potentially pathogenic mesophilic variant of , and the second, AG2.13.5, corresponds to an related to KN-Mc-11N1 with an ANI value of 97.32%. AG2.13.2 lacks the type III secretion system just like other mesophilic strains of . This characteristic has been associated with lower virulence. However, the genome of AG2.13.2 contains other important virulence factors such as type II and type VI secretion systems, and toxins such as , aerolysin /, and different types of hemolysins. The strain also carries several genes associated with antibiotic resistance such as the efflux pump, and exhibits resistance to tetracycline, ampicillin, and oxolinic acid. In an in vivo challenge test with gilthead seabream larvae, the bv strain AG5.28.6 exhibited the highest virulence among all tested strains. Conversely, both and showed minimal virulence when administered alone. Interestingly, when bv AG5.28.6 was co-administered with , the larvae survival probability increased compared to those exposed to bv AG5.28.6 alone. This finding indicates an antagonistic interaction between bv AG5.28.6 and AG2.13.5. The co-administration of bv AG5.28.6 with did not yield distinct survival probabilities. Our results validate that the primary pathogen responsible for European seabass aeromoniasis is bv .
PubMed: 38003801
DOI: 10.3390/pathogens12111337 -
Cellular and Molecular Biology... Oct 2023The present study was designed to assess the influence of dietary supplementation with chestnut bee pollen at various levels in rainbow trout, Oncorhynchus mykiss. For...
Dietary chestnut bee pollen as an immunostimulant for rainbow trout (Oncorhynchus mykiss): Effects on the growth, haematological values, immune response, oxidant/antioxidant status, and survival against Aeromonas salmonicida subsp. achromogenes.
The present study was designed to assess the influence of dietary supplementation with chestnut bee pollen at various levels in rainbow trout, Oncorhynchus mykiss. For two weeks feeding period, a total of 300 fish were allocated into 12 fiberglass tanks and divided into four equal groups, three replicates each, with chestnut bee pollen (BP) dietary inclusion as follows; the fish group was given a basal diet (C); fish group fed a diet supplemented with BP 1% (BP-1); fish group fed a diet supplemented with BP 2% (BP-2); and fish group fed a diet supplemented with BP 4% (BP-3). At the end of the experiment, growth, haematological values, immune status, antioxidant status, and survival rate against Aeromonas salmonicida subsp. achromogenes were evaluated. Dietary supplementation with chestnut bee pollen significantly improves growth performance. Fish fed the diets containing chestnut bee pollen had higher the haematological values than those fed the control diet. The results showed that all the immunological parameters in the groups fed with chestnut bee pollen were significantly higher when compared to the control group. Moreover, dietary chestnut bee pollen increased disease resistance against Aeromonas salmonicida subsp. achromogenes compared to the control group. The tissue SOD, CAT and GSH-Px activities of groups fed with chestnut bee pollen significantly enhanced when compared with the control groups. In contrast, the tissue MDA levels in all groups fed with chestnut bee pollen were significantly decreased. The best values for the antioxidant parameters were determined in the groups fed with 2 and 4% of chestnut bee pollen. Overall, these findings suggest that dietary chestnut bee pollen enhances the growth, the haematological values, the immune and antioxidant response and increases disease resistance against rainbow trout.
Topics: Animals; Bees; Antioxidants; Oncorhynchus mykiss; Disease Resistance; Oxidants; Adjuvants, Immunologic; Dietary Supplements; Diet; Pollen; Animal Feed; Fish Diseases
PubMed: 37953565
DOI: 10.14715/cmb/2023.69.10.26 -
Journal of Fish Diseases Feb 2024Here, we provide evidence that the freshwater parasitic copepod, Salmincola californiensis, acts as a vector for Aeromonas salmonicida. While investigating the effects...
Here, we provide evidence that the freshwater parasitic copepod, Salmincola californiensis, acts as a vector for Aeromonas salmonicida. While investigating the effects of S. californiensis on Chinoook salmon (Oncorhynchus tshawytscha), we tangentially observed that fish infected with the copepod developed furunculosis, caused by A. salmonicida. This occurred despite being reared in pathogen-free well water in a research facility with no prior history of spontaneous infection. We further investigated the possibility of S. californiensis to serve as a vector for the bacterium via detection of fluorescently labelled A. salmonicida inside the egg sacs from copepods in which the fish hosts were experimentally infected with GFP-A449 A. salmonicida. We then evaluated copepod egg sacs that were collected from adult Chinook salmon from a freshwater hatchery with A. salmonicida infections confirmed by either culture or PCR. The bacterium was cultured on tryptic soy agar plates from 75% of the egg sacs, and 61% were positive by PCR. These three separate experiments indicate an alternative tactic of transmission in addition to direct transmission of A. salmonicida in captivity. The copepod may play an important role in transmission of the bacterium when fish are more dispersed, such as in the wild.
Topics: Animals; Furunculosis; Salmonidae; Aeromonas salmonicida; Copepoda; Fish Diseases; Salmon; Fresh Water; Gram-Negative Bacterial Infections; Aeromonas
PubMed: 37947250
DOI: 10.1111/jfd.13885 -
Comparative Biochemistry and... 2024The caspase, functioning as a proteinase, plays a crucial role in eukaryotic cell apoptosis, regulation of apoptosis, cellular growth, differentiation, and immunity. The...
The caspase, functioning as a proteinase, plays a crucial role in eukaryotic cell apoptosis, regulation of apoptosis, cellular growth, differentiation, and immunity. The identification of caspase gene family in Sebastes schlegelii is of great help to understand its antimicrobial research. In S. schlegelii, we totally identified nine caspase genes, including four apoptosis initiator caspases (caspase 2, caspase 8, caspase 9 and caspase 10), four apoptosis executioners (caspase 3a, caspase 3b, caspase 6, and caspase 7) and one inflammatory executioner (caspase 1). The duplication of caspase 3 genes on chr3 and chr8 may have been facilitated by whole genome duplication (WGD) events or other complex evolutionary processes. In general, the number of caspase genes relatively conserved in high vertebrates, while exhibiting variation in teleosts. Furthermore, syntenic analysis and phylogenetic relationships analysis supported the correct classification of these caspase gene family in S. schlegelii, especially for genes with duplicated copies. Additionally, the expression patterns of these caspase genes in different tissues of S. schlegelii under healthy conditions were assessed. The results revealed that the expression levels of most caspase genes were significantly elevated in the intestine, spleen, and liver. To further investigate the potential immune functions of these caspase genes in S. schlegelii, we challenged individuals with A. salmonicida and V. anguillarum, respectively. After infection with A. salmonicida, the expression levels of caspase 1 in the liver and spleen of S. schlegelii remained consistently elevated throughout the infection time points. The expression levels of most caspase family members in the intestine exhibited significant divergence following V. anguillarum infection. This study provides a comprehensive understanding of the caspase gene families in S. schlegelii, thereby establishing a solid foundation for further investigations into the functional roles of these caspase genes.
Topics: Humans; Animals; Aeromonas salmonicida; Fish Proteins; Caspases; Phylogeny; Caspase 1; Amino Acid Sequence; Perciformes; Vibrio; Vibrio Infections; Fish Diseases
PubMed: 37913865
DOI: 10.1016/j.cbpb.2023.110913 -
Natural Product Research Oct 2023A series of 6 novel ester derivatives of natural product geodin were designed and semi-synthesized through one mild step reaction with high yield. Compounds showed...
A series of 6 novel ester derivatives of natural product geodin were designed and semi-synthesized through one mild step reaction with high yield. Compounds showed strong inhibitory activities against in the range of 2.35-9.41 M. Compounds and showed very strong inhibitory activities against antifouling bacteria with MICs of 2.42 M and 4.56 M respectively. Most notably compounds showed potent antifungal activities against in the range of 0.59-2.44 M. Particularly, compound showed the highest antifungal activity against with a MIC value of 0.59 M. The preliminary structure activity relationship of these derivatives showed that replacement of 4-OH group with benzoyl substituents could enhance the antibacterial and antifungal activities of geodin .
PubMed: 37865972
DOI: 10.1080/14786419.2023.2272022 -
Fish & Shellfish Immunology Dec 2023Turbot (Scophthalmus maximus) is a commercially important marine flatfish for global aquaculture. With intensive farming, turbot production is limited by several...
Turbot (Scophthalmus maximus) is a commercially important marine flatfish for global aquaculture. With intensive farming, turbot production is limited by several diseases, in which Aeromonas salmonicida and Edwardsiella tarda are two main causative agents. Vaccination is an effective and safe alternative to disease prevention compared to antibiotic treatment. In the previous study, we developed an inactivated bivalent vaccine against A. salmonicida and E. tarda with relative percent survival (RPS) of 77.1 %. To understand the protection mechanism in molecular basis of the inactivated bivalent vaccine against A. salmonicida and E. tarda, we use RNA-seq to analyze the transcriptomic profile of the kidney tissue after immunization. A total of 391,721,176 clean reads were generated in nine libraries by RNA-seq, and 96.35 % of the clean reads were mapped to the reference genome of S. maximus. 1458 (866 upregulated and 592 downregulated) and 2220 (1131 upregulated and 1089 downregulated) differentially expressed genes (DEGs) were obtained at 2 and 4 weeks post-vaccination, respectively. The DEGs were enriched in several important immune-related GO terms, including cytokine activity, immune response, and defense response. In addition, the analysis of several immune-related genes showed upregulation and downregulation, including pattern recognition receptors, complement system, cytokines, chemokines and immune cell surface markers. Eight DEGs (ccr10, calr, casr, mybpha, cd28, thr18, cd20a.3 and c5) were randomly selected for qRT-PCR analysis, which confirmed the validity of the RNA-seq. Our results provide valuable insight into the immune mechanism of inactivated bivalent vaccine against A. salmonicida and E. tarda in Scophthalmus maximus.
Topics: Animals; Edwardsiella tarda; Aeromonas salmonicida; Fish Diseases; Flatfishes; Vaccines, Inactivated; Gene Expression Profiling; Transcriptome; Kidney; Vaccines, Combined
PubMed: 37858783
DOI: 10.1016/j.fsi.2023.109174 -
Microbial Pathogenesis Dec 2023Zebrafish (Danio rerio) is an excellent model to study bacterial infections in fish and their treatment. We used zebrafish as a model of infection for Aeromonas...
Zebrafish (Danio rerio) is an excellent model to study bacterial infections in fish and their treatment. We used zebrafish as a model of infection for Aeromonas salmonicida subsp. salmonicida (hereinafter A. salmonicida), the causative agent of fish furunculosis. The infection process of A. salmonicida was studied by immersion of zebrafish larvae in 2 different doses of the bacteria and the fish mortality was monitored for three days. The bacterium caused a high mortality (65 %) in zebrafish larvae only when they were exposed to a high bacterial concentration (10 bacterial cells/mL). To evaluate the use of fluorescence microscopy to follow A. salmonicida infection in vivo, two different fluorescent strains generated by labeling an A. salmonicida strain with either, the green fluorescent protein (GFP), or with a previously reported siderophore amonabactin-sulforhodamine B conjugate (AMB-SRB), were used. The distribution of both labeled bacterial strains in the larvae tissues was evaluated by conventional and confocal fluorescence microscopy. The fluorescent signal showed a greater intensity with the GFP-labeled bacteria, so it could be observed using conventional fluorescence microscopy. Since the AMB-SRB labeled bacteria showed a weaker signal, the larvae were imaged using a laser scanning confocal microscope after 48 h of exposure to the bacteria. Both fluorescent signals were mainly observed in the larvae digestive tract, suggesting that this is the main colonization route of zebrafish for waterborne A. salmonicida. This is the first report of the use of a siderophore-fluorophore conjugate to study a bacterial infection in fish. The use of a siderophore-fluorophore conjugate has the advantage that it is a specific marker and that does not require genetic manipulation of the bacteria.
Topics: Animals; Siderophores; Zebrafish; Fluorescent Dyes; Green Fluorescent Proteins; Aeromonas salmonicida; Fish Diseases
PubMed: 37858632
DOI: 10.1016/j.micpath.2023.106394 -
Microbiology Resource Announcements Nov 2023, a Gram-negative bacterium, causes the disease furunculosis in multiple fish species. We present the complete genome sequence of the atypical strain T30, which was...
, a Gram-negative bacterium, causes the disease furunculosis in multiple fish species. We present the complete genome sequence of the atypical strain T30, which was isolated from furunculosis in sablefish in Manchester, WA, USA. Analyzing this genome will help to identify the bacterium's role in marine aquaculture.
PubMed: 37855633
DOI: 10.1128/MRA.00535-23 -
Environmental Research Dec 2023The overuse of antibiotics in aquaculture drives the emergence of multi-drug-resistant bacteria, and antibiotic-resistant genes (ARGs) can be disseminated to other...
The overuse of antibiotics in aquaculture drives the emergence of multi-drug-resistant bacteria, and antibiotic-resistant genes (ARGs) can be disseminated to other bacteria through vertical- and horizontal gene transfer (VGT and HGT) under selective pressure. Profiling the antibiotic resistome and understanding the global distribution of ARGs constitutes the first step in developing a control strategy. Hence, this study utilized extensive genomic data from hundreds of Aeromonas strains in aquaculture to profile resistome patterns and explores their association with isolation year, country, and species characteristics. Overall, ∼400 Aeromonas genomes were used to predict the ARGs from A. salmonicida, A. hydrophila, A. veronii, A. media, and A. sobria. ARGs such as sul1, tet(A), and tet(D), which display a similar proportion of positive strains among species, were subjected to phylodynamic and phylogeographic analyses. More than a hundred ARGs were identified, some of which exhibited either species-specific or non-species-specific patterns. A. salmonicida and A. media were found to have a higher proportion of species-specific ARGs than other strains, which might lead to more distinct patterns of ARG acquisition. Overall, ∼25% of strains have either sul1, tet(A), or tet(D) gene(s), but no significant difference was observed in the proportion of positive strains by species. Phylogeographic analysis revealed that the abundant numbers of sul1, tet(A), and/or tet(D) introduced in a few East Asian and North American countries could spread to both adjacent and faraway countries. In recent years, the proportions of these ARGs have dramatically increased, particularly in strains sourced from aquatic environments, suggesting control is required of the overuse of antibiotics in aquaculture. The findings of this research offer significant insights into the global dissemination of ARGs.
Topics: Aeromonas; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Aquaculture; North America; Genes, Bacterial
PubMed: 37805184
DOI: 10.1016/j.envres.2023.117273