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Fish & Shellfish Immunology May 2024In mammals, β-catenin participates in innate immune process through interaction with NF-κB signaling pathway. However, its role in teleost immune processes remains...
In mammals, β-catenin participates in innate immune process through interaction with NF-κB signaling pathway. However, its role in teleost immune processes remains largely unknown. We aimed to clarify the function of β-catenin in the natural defense mechanism of Qi river crucian carp (Carassius auratus). β-catenin exhibited a ubiquitous expression pattern in adult fish, as indicated by real-time PCR analysis. Following lipopolysaccharide (LPS), Polyinosinic-polycytidylic acid (polyI: C) and Aeromonas hydrophila (A. hydrophila) challenges, β-catenin increased in gill, intestine, liver and kidney, indicating that β-catenin likely plays a pivotal role in the immune response against pathogen infiltration. Inhibition of the β-catenin pathway using FH535, an inhibitor of Wnt/β-catenin pathway, resulting in pathological damage of the gill, intestine, liver and kidney, significant decrease of innate immune factors (C3, defb3, LYZ-C, INF-γ), upregulation of inflammatory factors (NF-κB, TNF-α, IL-1, IL-8), and downregulation of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) activities, increase of Malondialdehyde (MDA) content. Following A. hydrophila invasion, the mortality rate in the FH535 treatment group exceeded that of the control group. In addition, the diversity of intestinal microflora decreased and the community structure was uneven after FH535 treatment. In summary, our findings strongly suggest that β-catenin plays a vital role in combating pathogen invasion and regulating intestinal flora in Qi river crucian carp.
Topics: Animals; Goldfish; Carps; Gastrointestinal Microbiome; NF-kappa B; Rivers; beta Catenin; Qi; Immunity, Innate; Antioxidants; Aeromonas hydrophila; Fish Diseases; Fish Proteins; Gram-Negative Bacterial Infections; Mammals; Sulfonamides
PubMed: 38552889
DOI: 10.1016/j.fsi.2024.109521 -
Journal of Global Antimicrobial... Jun 2024Herein, we detected one multidrug-resistant Aeromonas hydrophila strain K522 co-carrying two bla genes together with a novel chromosomal integrative and mobilizable...
Coexistence of a novel chromosomal integrative and mobilizable element Tn7548 with two bla-carrying plasmids in a multidrug-resistant Aeromonas hydrophila strain K522 from China.
OBJECTIVES
Herein, we detected one multidrug-resistant Aeromonas hydrophila strain K522 co-carrying two bla genes together with a novel chromosomal integrative and mobilizable element (IME) Tn7548 from China. To reveal the genetic characteristics of the novel reservoir of bla and IME in Aeromonas, a detailed genomic characterization of K522 was performed, and a phylogenetic analysis of Tn7412-related IMEs was carried out.
METHODS
Carbapenemases were detected by using the immunocolloidal gold technique and antimicrobial susceptibility was tested by using VITEK 2. The whole-genome sequences of K522 were analysed using phylogenetics, detailed dissection, and comparison.
RESULTS
Strain K522 carried a Tn7412-related chromosomal IME Tn7548 and three resistance plasmids pK522-A-KPC, pK522-B-KPC, and pK522-MOX. A phylogenetic tree of 82 Tn7412-related IMEs was constructed, and five families of IMEs were divided. These IMEs shared four key backbone genes: int, repC, and hipAB, and carried various profiles of antimicrobial resistance genes (ARGs). pK522-A-KPC and pK522-B-KPC carried bla and belonged to IncG and unclassified type plasmid, respectively. The bla regions of these two plasmids were the truncated version derived from Tn6296, resulting in the carbapenem resistance of K522.
CONCLUSION
We first reported A. hydrophila harbouring a novel Tn7412-related IME Tn7548 together with two bla carrying plasmids and a MDR plasmid. Three of these four mobile genetic elements (MGEs) discovered in A. hydrophila K522 were novel. The emergence of novel MGEs carrying ARGs indicated the rapid evolution of the resistance gene vectors in A. hydrophila under selection pressure and would contribute to the further dissemination of various ARGs in Aeromonas.
Topics: Aeromonas hydrophila; Plasmids; Drug Resistance, Multiple, Bacterial; China; beta-Lactamases; Phylogeny; Humans; Bacterial Proteins; Microbial Sensitivity Tests; Anti-Bacterial Agents; Whole Genome Sequencing; Gram-Negative Bacterial Infections; DNA Transposable Elements; Chromosomes, Bacterial
PubMed: 38552873
DOI: 10.1016/j.jgar.2024.03.006 -
PloS One 2024Aeromonas hydrophila is one of the major pathogenic bacteria responsible for causing severe outbreaks at fish farms and is also a major global public health concern....
Aeromonas hydrophila is one of the major pathogenic bacteria responsible for causing severe outbreaks at fish farms and is also a major global public health concern. This bacterium harbors many virulence genes. The current study was designed to evaluate the antidrug and virulence potential of A. hydrophila by amplifying its antimicrobial resistance and virulence genes using PCR and examining their effects on fish tissues and organs. A total of 960 fish samples of Channa marulius and Sperata sarwari were collected from four sites of the rivers of the Punjab, Pakistan. A. hydrophila isolates were subjected to biochemical identification and detection of virulence and antimicrobial resistance (AMR) genes by PCR. We retrieved 181 (6.46%) A. hydrophila isolates from C. marulius and 177 (6.25%) isolates from S. sarwari. Amplification through PCR revealed the incidence of virulence genes in 95.7% of isolates in C. marulius and 94.4% in S. sarwari. Similarly, amplification through PCR also revealed occurrence of AMR genes in 87.1% of isolates in C. marulius and 83.9% in S. sarwari. Histopathological examination revealed congestion (5.2%) and hepatocyte necrosis (4.6%) in liver, lamellar fusion (3.3%) and the presence of bacterial colonies (3.7%) in gills, fin erosion (6%), and the presence of biofilms (3.5%) in tail fins of infected fish. Phylogenetic tree analysis of 16S rRNA and gyrB gene of A. hydrophila revealed 100% and 97% similarity, respectively, with 16S rRNA gene and gyrB of A. hydrophila isolated in previous studies. The results of antimicrobial susceptibility testing showed that all isolates demonstrated resistance to sulfamethoxazole, ampicillin, neomycin, and norfloxacin, while susceptibility to gentamicin, chloramphenicol, and tetracycline, and intermediate resistance was observed against cefotaxime. The results concluded that examined fish samples were markedly contaminated with virulent and multidrug strains of A. hydrophila which may be of a potential health risk. The study emphasizes the responsible antimicrobial use in aquaculture and the urgent need for effective strategies to control the spread of virulence and antimicrobial resistance genes in A. hydrophila.
Topics: Animals; Aeromonas hydrophila; Phylogeny; Pakistan; RNA, Ribosomal, 16S; Anti-Bacterial Agents; Catfishes; Aeromonas; Gram-Negative Bacterial Infections
PubMed: 38551906
DOI: 10.1371/journal.pone.0297979 -
PloS One 2024Aeromonas spp. are the opportunistic pathogens that infect both aquatic and terrestrial homeotherms. They were commonly present in aquatic environments, including...
Aeromonas spp. are the opportunistic pathogens that infect both aquatic and terrestrial homeotherms. They were commonly present in aquatic environments, including effluent, tap water, marine, river, and lake, where they are often isolated from aquatic animals, including fish, molluscs, and crustaceans. The Aeromonas infections can cause sepsis, ulcer, and other symptoms, resulting in the death of massive aquatic animals. Therefore, the prevention and control of Aeromonas is of great significance for the healthy development of aquaculture. In this study, we used modern molecular methods to enhance disease control of Aeromonas isolates from freshwater fish in Hebei Province. A total of 130 Aeromonas spp. isolates were isolated from freshwater fish farms in Hengshui, Handan, and Shijiazhuang and all 130 Aeromonas spp. isolates were sequenced for species identification. Of the 130 Aeromonas spp. isolates, 104 isolates were successfully sequenced, and BLAST analysis showed that Aeromonas veronii was predominant in freshwater fish farms in Hebei Province. In addition, 26 antibiotic resistance profiles were obtained from 102 fully cultured isolates among the 104 Aeromonas spp. isolates whose species was primarily identified, and 44 multidrug-resistant bacteria among the 102 isolates were identified using an antibiotic susceptibility test. Using the Multilocus Sequence Typing (MLST) method, 33 out of 44 multidrug-resistant isolates with 14 non-Aeromonas reference strains were selected for phylogenetic and MLST analysis, and all 33 multidrug-resistant isolates were A. veronii. A total of 30 new Sequence Types (STs) were obtained by comparing concatenated sequences (gyrB-groL-gltA-metG-ppsA-recA) on PubMLST website. Furthermore, recombination event analysis detected using RDP5 and ClonalFrameML software 42 and 49 recombination events, respectively, and 22 recombination events were validated by four or more algorithms. Since mutation and recombination events increase clonal diversity and single housekeeping gene sequence alignments are limited for identifying species, we propose the use of multiple concatenated sequence loci to increase discriminatory power. In addition, we propose that the MLST method is an appropriate technique to study and develop the resistance mechanisms of multidrug-resistant Aeromonas and to identify Aeromonas systematically in complex samples obtained from the environment.
Topics: Animals; Aeromonas; Multilocus Sequence Typing; Anti-Bacterial Agents; Phylogeny; Fishes; Drug Resistance, Multiple, Bacterial; Fresh Water
PubMed: 38536889
DOI: 10.1371/journal.pone.0298745 -
The ISME Journal Jan 2024Intestinal microbial disturbance is a direct cause of host disease. The bacterial Type VI secretion system (T6SS) often plays a crucial role in the fitness of pathogenic...
Intestinal microbial disturbance is a direct cause of host disease. The bacterial Type VI secretion system (T6SS) often plays a crucial role in the fitness of pathogenic bacteria by delivering toxic effectors into target cells. However, its impact on the gut microbiota and host pathogenesis is poorly understood. To address this question, we characterized a new T6SS in the pathogenic Aeromonas veronii C4. First, we validated the secretion function of the core machinery of A. veronii C4 T6SS. Second, we found that the pathogenesis and colonization of A. veronii C4 is largely dependent on its T6SS. The effector secretion activity of A. veronii C4 T6SS not only provides an advantage in competition among bacteria in vitro, but also contributes to occupation of an ecological niche in the nutritionally deficient and anaerobic environment of the host intestine. Metagenomic analysis showed that the T6SS directly inhibits or eliminates symbiotic strains from the intestine, resulting in dysregulated gut microbiome homeostasis. In addition, we identified three unknown effectors, Tse1, Tse2, and Tse3, in the T6SS, which contribute to T6SS-mediated bacterial competition and pathogenesis by impairing targeted cell integrity. Our findings highlight that T6SS can remodel the host gut microbiota by intricate interplay between T6SS-mediated bacterial competition and altered host immune responses, which synergistically promote pathogenesis of A. veronii C4. Therefore, this newly characterized T6SS could represent a general interaction mechanism between the host and pathogen, and may offer a potential therapeutic target for controlling bacterial pathogens.
Topics: Type VI Secretion Systems; Gastrointestinal Microbiome; Aeromonas veronii; Symbiosis; Ecosystem; Bacterial Proteins
PubMed: 38531781
DOI: 10.1093/ismejo/wrae053 -
Journal of Fish Diseases Jul 2024Aeromonas salmonicida, a widely distributed aquatic pathogen causing furunculosis in fish, exhibits varied virulence, posing challenges in infectious disease and...
Aeromonas salmonicida, a widely distributed aquatic pathogen causing furunculosis in fish, exhibits varied virulence, posing challenges in infectious disease and immunity studies, notably in vaccine efficacy assessment. Lumpfish (Cyclopterus lumpus) has become a valuable model for marine pathogenesis studies. This study evaluated several antigen preparations against A. salmonicida J223, a hypervirulent strain of teleost fish, including lumpfish. The potential immune protective effect of A. salmonicida bacterins in the presence and absence of the A-layer and extracellular products was tested in lumpfish. Also, we evaluated the impact of A. salmonicida outer membrane proteins (OMPs) and iron-regulated outer membrane proteins (IROMPs) on lumpfish immunity. The immunized lumpfish were intraperitoneally (i.p.) challenged with 10 A. salmonicida cells/dose at 8 weeks-post immunization (wpi). Immunized and non-immunized fish died within 2 weeks post-challenge. Our analyses showed that immunization with A. salmonicida J223 bacterins and antigen preparations did not increase IgM titres. In addition, adaptive immunity biomarker genes (e.g., igm, mhc-ii and cd4) were down-regulated. These findings suggest that A. salmonicida J223 antigen preparations hinder lumpfish immunity. Notably, many fish vaccines are bacterin-based, often lacking efficacy evaluation. This study offers crucial insights for finfish vaccine approval and regulations.
Topics: Animals; Aeromonas salmonicida; Fish Diseases; Adaptive Immunity; Gram-Negative Bacterial Infections; Bacterial Vaccines; Furunculosis; Perciformes; Antigens, Bacterial
PubMed: 38523320
DOI: 10.1111/jfd.13944 -
Developmental and Comparative Immunology Jul 2024Low-oxygen levels (hypoxia) in aquatic habitats are becoming more common because of global warming and eutrophication. However, the effects on the health/disease status...
Low-oxygen levels (hypoxia) in aquatic habitats are becoming more common because of global warming and eutrophication. However, the effects on the health/disease status of fishes, the world's largest group of vertebrates, are unclear. Therefore, we assessed how long-term hypoxia affected the immune function of sablefish, an ecologically and economically important North Pacific species, including the response to a formalin-killed Aeromonas salmonicida bacterin. Sablefish were held at normoxia or hypoxia (100% or 40% air saturated seawater, respectively) for 6-16 weeks, while we measured a diverse array of immunological traits. Given that the sablefish is a non-model organism, this involved the development of a species-specific methodological toolbox comprised of qPCR primers for 16 key immune genes, assays for blood antibacterial defences, the assessment of blood immunoglobulin (IgM) levels with ELISA, and flow cytometry and confocal microscopy techniques. We show that innate immune parameters were typically elevated in response to the bacterial antigens, but were not substantially affected by hypoxia. In contrast, hypoxia completely prevented the ∼1.5-fold increase in blood IgM level that was observed under normoxic conditions following bacterin exposure, implying a serious impairment of adaptive immunity. Since the sablefish is naturally hypoxia tolerant, our results demonstrate that climate change-related deoxygenation may be a serious threat to the immune competency of fishes.
Topics: Animals; Adaptive Immunity; Climate Change; Aeromonas salmonicida; Fish Diseases; Hypoxia; Immunity, Innate; Immunoglobulin M; Fishes; Oxygen; Gram-Negative Bacterial Infections; Antigens, Bacterial
PubMed: 38521379
DOI: 10.1016/j.dci.2024.105161 -
Microbiology Spectrum May 2024Hospital sewage serves as a crucial reservoir for antibiotic resistance genes. As colistin and carbapenems are the last-resort antibiotics, the emergence of their...
Hospital sewage serves as a crucial reservoir for antibiotic resistance genes. As colistin and carbapenems are the last-resort antibiotics, the emergence of their resistance genes has become a significant concern in clinical settings. In this study, we found that two novel alleles (.43 and .2) with two carbapenemase genes ( and ) were encoded in a single strain isolated from hospital sewage. Our phylogenetic analysis revealed that the gene clustered with (with 95.55% amino acid identity), while the gene clustered with (with 68.68% amino acid identity). BLAST search against GenBank showed that was exclusively detected in spp. Mobile genetic elements were not found in the genetic context of , suggesting that the dissemination of in spp. may be dependent on vertical transfer or recombination. The was adjacent to a recombinase gene and flanked by two IS elements, indicating a potential mobilization mechanism mediated by recombination and/or ISs. The gene was located on an IncU plasmid and adjacent to an IS. In summary, our study provides evidence for spp. as one of the potential reservoirs of colistin and carbapenem resistance genes.IMPORTANCEThe study discovered two novel genes ( and ) and two carbapenemase genes ( and ) in a single strain retrieved from hospital sewage. Using phylogenetic analysis and comparative data evaluation, the study revealed the genetic relatedness and dissemination potential of the detected resistance genes. With the exclusive discovery that is only present in spp. and the lack of mobile genetic elements in its genetic context, there is a strong indication of limited dissemination. The identification of these four resistance genes in a single strain of provided valuable insights into their potential presence in this genus. This study revealed that hospital sewage functions as a significant reservoir for antibiotic resistance genes, including colistin and carbapenem resistance genes.
Topics: beta-Lactamases; Bacterial Proteins; Anti-Bacterial Agents; Drug Resistance, Multiple, Bacterial; Phylogeny; Aeromonas caviae; Microbial Sensitivity Tests; Sewage; Colistin; Carbapenems; Humans; Plasmids
PubMed: 38511954
DOI: 10.1128/spectrum.03685-23 -
Frontiers in Cellular and Infection... 2024This investigation delves into elucidating the mechanism by which resveratrol (Res), a natural polyterpenoid renowned for its antimicrobial properties, exerts its...
This investigation delves into elucidating the mechanism by which resveratrol (Res), a natural polyterpenoid renowned for its antimicrobial properties, exerts its effects on , a ubiquitous waterborne pathogen. Our findings underscore the dose-dependent manifestation of resveratrol in exhibiting antibacterial and antibiofilm formation activities against . Employing a Data-independent acquisition (DIA) based quantitative proteomics methodology, we systematically compared differentially expressed proteins in subjected to varying concentrations of Res. Subsequent bioinformatics analyses revealed key proteins and pathways pivotal in resveratrol's antimicrobial action, encompassing oxidative stress, energy metabolism, and cell membrane integrity. Validation of the proteomics outcomes was meticulously conducted using the qPCR method at the mRNA level. Dynamic trend analysis unveiled alterations in biological processes, notably the correlation between the cell division-related protein ZapC and resveratrol content. Furthermore, scanning electron microscopy corroborated a significant elongation of cells, affirming resveratrol's capability to inhibit cell division. In concert, resveratrol emerges as a participant in the cell membrane integrity pathway, biofilm formation, and potentially, the regulation of genes associated with cell division, resulting in morphological elongation. These revelations position resveratrol as a promising natural alternative to conventional antibiotics for treating infections.
Topics: Humans; Aeromonas hydrophila; Resveratrol; Proteomics; Bacterial Proteins; Anti-Bacterial Agents
PubMed: 38510959
DOI: 10.3389/fcimb.2024.1378094 -
Fish & Shellfish Immunology May 2024Aeromonas hydrophila is a commonly pathogenic bacterium in cultivated eels, but its pathogenicity to American eel (Anguilla rostrata) and the molecular mechanism of host...
Aeromonas hydrophila is a commonly pathogenic bacterium in cultivated eels, but its pathogenicity to American eel (Anguilla rostrata) and the molecular mechanism of host anti-A. hydrophila infection remains uncertain. In this study, LD of A. hydrophila to American eels was determined and bacterial load in the liver and kidney of eels was assessed post 2.56 doses of LD of A. hydrophila infection. The results showed that the LD of A. hydrophila to American eels was determined to be 3.9 × 10 cfu/g body weight (7.8 × 10 cfu/fish), and the bacterial load peaked at 36 h post the infection (hpi) in the liver. Then, the histopathology was highlighted by congestion in splenic blood vessels, atrophied glomeruli, and necrotic hepatocytes. Additionally, the results of qRT-PCR revealed that 18 host immune-related genes showed significantly up or downregulated post-infection compare to that of pre-infection. Finally, results of the RNA-seq revealed 10 hub DEGs and 7 encoded proteins play essential role to the anti-A. hydrophila infection in American eels. Pathogenicity of A. hydrophila to American eels and RNA-seq of host anti-A. hydrophila infection were firstly reported in this study, shedding new light on our understanding of the A. hydrophila pathogenesis and the host immune response to the A. hydrophila infection strategies in gene transcript.
Topics: Animals; Aeromonas hydrophila; Anguilla; Virulence; Bacterial Outer Membrane Proteins; Gene Expression Profiling; Fish Diseases
PubMed: 38508539
DOI: 10.1016/j.fsi.2024.109504