Search Results (103)

Furunculosis caused by Aeromonas salmonicida is one of the most common diseases in aquaculture, leading to significant economic losses. This study comprehensively investigated the dynamics of pathophysiological and histopathological disorders in rainbow trout (Oncorhynchus mykiss) infected with the moderately virulent strain A. salmonicida SL0n. Whole-genome analysis showed that strain SL0n belongs to the A. salmonicida species complex, possessing a single circular chromosome. The genome encodes a wide range of virulence factors, including adhesion systems (type IV pili, fimbriae), toxins (aerolysin, hemolysins), and a type II secretion system (T2SS), but notably lacks plasmids and a type III secretion system (T3SS). This genomic profile likely dictates a pathogenic mechanism reliant on secreted exotoxins (via T2SS), explaining the observed systemic cytotoxic damage. In an acute experiment, the 4-day LD₅₀ was determined to be 1.63 × 10⁶ CFU/fish. In a prolonged experiment, fish were injected with a sublethal dose (1.22 × 10⁶ CFU/fish—75% of LD50). The disease progressed through three consecutive stages. The early stage (1–2 DPI) was characterized by maximal bacterial load and activation of nonspecific immunity. The acute stage (4 DPI) manifested as severe septicemia and anemia, associated with systemic organ damage, which correlated with peak AST and ALT enzyme activity. The recovery stage (6 DPI) was marked by partial regression of inflammation, key biochemical and histological parameters indicated persistent liver and kidney dysfunction, signifying an incomplete recovery. These results demonstrate the pathogenesis of acute furunculosis and reveal that the genomic profile of the SL0n strain causes a sequential, systemic infection characterized by severe organ dysfunction. Full article

Background/Objectives: The renin–angiotensin system (RAS) is well-established as a moderator of cardiovascular equilibrium and blood pressure. Nevertheless, growing evidence indicates that angiotensin II (Ang II), the principal RAS effector peptide, together with additional constituents, is involved in various malignancies. Since the immune system is an important aspect in tumor development, this study sought to investigate the role of Ang II in the crosstalk between tumor-associated macrophages (TAMs) and breast cancer cells in the tumor microenvironment (TME). Methods: We treated THP-1-like macrophages with 100 nM Ang II for 24 h. The culture media thus obtained was used as conditioned media and applied at 50% on MCF-7 and MDA-MB-231 breast cancer cell lines. The effects of the conditioned media on cancer cell lines were then investigated by various methods such as a cell proliferation assay, migration assay, polarization assay, and by the detection of apoptosis and reactive oxygen species (ROS) generation. Results: We demonstrated that in vitro Ang II promotes macrophage polarization toward proinflammatory M1-like macrophages and anti-inflammatory M2-like macrophages. Interestingly, Ang II, through macrophages, showed varied effects on different breast cancer cell lines, promoting tumor growth and progression in MCF-7 while inhibiting tumor growth and progression in MDA-MB-23. Conclusions: This study has provided clear evidence that Ang II in the TME modulates TAM polarization and secretions, leading to different effects based on the type of breast cancer. Full article

The genus Xanthomonas (family Xanthomonadaceae) comprises 39 validly published species and is associated with a broad host range, infecting hundreds of monocot and dicot plants worldwide. While many Xanthomonas species are notorious for causing leaf spot and blight diseases in major agricultural crops, less attention has been given to their impact on ornamental plants. In Hawaii and other key production regions, xanthomonads have posed persistent threats to popular ornamentals in the Araceae and Araliaceae families. This review synthesizes the evolving phylogenetic and taxonomic framework of Xanthomonas strains isolated from Araceae and Araliaceae, highlighting recent advances enabled by multilocus sequence analysis and whole genome sequencing. We discuss the reclassification of key pathovars, unresolved phylogenetic placements, and the challenges of pathovar delineation within these plant families. Additionally, we examine current knowledge of molecular determinants of pathogenicity, including gene clusters involved in exopolysaccharide and lipopolysaccharide biosynthesis, flagellar assembly, cell-wall-degrading enzymes, and secretion systems (types II, III, and VI). Comparative genomics and functional studies reveal that significant gaps remain in our understanding of the genetic basis of host adaptation and virulence in these xanthomonads. Addressing these knowledge gaps will be crucial for developing effective diagnostics and management strategies for bacterial diseases in ornamental crops. Full article

The strain A-9^T, isolated from Oncorhynchus mykiss (rainbow trout) in a Turkish aquaculture facility, was characterized through integrated phenotypic, phylogenetic, and genomic analyses. Whole-genome sequencing revealed a 5.21 Mb circular chromosome (GC content: 58.16%) and three plasmids encoding proteins for mobilization and toxin–antitoxin systems. Multilocus phylogenetic analysis (MLPA) using seven housekeeping genes supported the distinct lineage of A-9^T. Digital DNA–DNA hybridization (77.6–78.6%) and average nucleotide identity values (96.59–97.58%) confirmed taxonomic divergence from all currently recognized A. salmonicida subspecies. Comparative proteomic and pangenomic analyses identified 328 strain-specific genes, including virulence factors, secretion system components (Type II and Type VI), and efflux-related proteins. Although genes encoding Type III secretion systems and biofilm formation were absent, A-9^T harbored a broad virulence gene repertoire and resistance determinants, including OXA-956, cphA5, and FOX-20, supporting a multidrug-resistant phenotype. Based on its genomic, phenotypic, and functional distinctiveness, we propose the novel taxon Aeromonas salmonicida subsp. oncorhynchi subsp. nov. (type strain A-9^T = LMG 33538^T = DSM 117494^T), expanding the taxonomic landscape of the A. salmonicida complex and offering insights into fish-associated bacterial evolution. Full article

Iron is essential for vital biological processes, with its metabolism closely linked to host–pathogen interactions. Pseudomonas donghuensis HYS, with its superior iron uptake capacity, demonstrates pronounced virulence toward Caenorhabditis elegans. However, the virulence mechanisms remain unexplored. Ferric uptake regulator (Fur) regulates iron homeostasis and pathogenicity in bacteria, yet its role in HYS-mediated C. elegans pathogenesis requires systematic investigation. In this study, comparing the pathogenic processes of HYS and P. aeruginosa PA14 revealed that HYS causes stronger, irreversible toxicity via distinct mechanisms. Transcriptomics revealed that HYS infection disrupts C. elegans iron metabolism pathways, specifically iron transport, and iron–sulfur cluster utilization. Fur was identified as a pivotal regulator in HYS virulence and was indispensable for its colonization. Specifically, Fur was critical for disrupting nematode iron metabolism, as fur deletion eliminated this effect. While Fur regulated two HYS siderophores, neither of them mediated in the iron metabolism disruption of C. elegans. Screening identified Fur-regulated virulence factors to further investigate the function of Fur in HYS virulence, particularly alkaline proteases, and type II secretion system components. This study highlight that HYS can disrupt the iron metabolism pathway in C. elegans; Fur serves as a pivotal positive regulator in HYS-induced damage, particularly in disrupting iron metabolism through a siderophore-independent pathway. These findings expand the understanding of Pseudomonas pathogenicity and Fur-mediated virulence regulation. Full article

Secreted protein acidic rich in cysteine (SPARC), one of the extracellular matrix proteins, is highly induced during inflammation. We investigated the pathophysiological regulation and role of SPARC in vascular inflammation in a rat model of hypertension created using deoxycorticosterone acetate (DOCA, 40 mg/kg/week, s.c.) and salt (1% in drinking water). DOCA–salt administration time-dependently increased systolic blood pressure during the 3-week treatment period, blunted endothelium-dependent vasodilation, and increased monocyte chemoattractant protein-1 (MCP-1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) expression in the aorta. SPARC expression transiently increased until week 2 in the DOCA–salt rat aorta. Interestingly, aortic SPARC levels correlated with blood pressure and the levels of MCP-1 and LOX-1 during 0–2 weeks. The AT₁ receptor blocker, losartan, suppressed the overexpression of SPARC, and in vitro treatment with angiotensin II enhanced the production of SPARC in rat aortic endothelial cells. Exposure to recombinant SPARC protein induced overexpression of MCP-1 and LOX-1 mRNA in endothelial cells. Bioactive forms of a disintegrin and metalloproteinase with thrombospondin type 1 motif (ADAMTS1), excessive activation of which contributes to pathological states and overexpression of which is reported to be induced by SPARC, were increased in the DOCA–salt rat aorta. These results suggest that SPARC is induced by the vascular renin–angiotensin system and causes inflammation in the early stages of hypertensive vascular injury, and that activation of ADAMTS1 might be related to the proinflammatory effects of SPARC. Full article

Cadmium (Cd) is a toxic, non-essential metal that primarily enters animal bodies through the digestive and respiratory systems, leading to damage to multiple organs and tissues. Cd can accumulate in cartilage and induce damage to chondrocytes. Procyanidins (PAs), also known as concentrated tannic acid or oligomeric proanthocyanidins (OPCs), exhibit diverse biological and pharmacological activities. However, the mechanism of OPCs alleviates Cd-induced damage to chondrocytes in chickens remains to be further explored in vitro. Chondrocytes were isolated from both ends of the tibia of 17-day-old SPF chicken embryos, and then subsequently treated with various concentrations of Cd (0, 1, 2.5, 5, and 10 μmol/L) or OPCs (0, 5, 10, 20, and 40 μmol/L) to investigate the mechanism underlying extracellular matrix (ECM) degradation and damage. Cd reduced cell viability, glycosaminoglycan (GAG) secretion, and ECM degradation in chondrocytes by decreasing the expression of type II collagen alpha 1 (COL2A1) and aggrecan (ACAN) while increasing the release of cartilage oligomeric matrix protein (COMP), along with elevated levels of matrix-degrading enzymes, such as matrix metalloproteinases 1 (MMP1), MMP10, and MMP13, and a disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS4) and ADAMTS5. Cd induced phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2) and the expression of matrix-degrading enzymes, impairing ECM synthesis, an effect that could be alleviated by ERK1/2 inhibitor U0126. Chondrocytes were treated with 5 μmol/L Cd and 10 μmol/L OPCs, and it was found that OPCs inhibited the activation of the ERK1/2 signaling pathway and the expression of matrix-degrading enzymes, while promoting ECM synthesis and alleviating Cd-induced ECM damage in chickens. This study provides a theoretical basis for clinical research on OPCs with respect to the prevention and treatment of Cd-induced chondrogenic diseases in poultry. Full article

Interferon-γ (IFN-γ), a member of the Type II IFN family, is a crucial cytokine in the immune system and serves as an important indicator of immune response. Intracellular cytokine staining (ICS) is a technique used to analyze the production of cytokines within individual cells, and it has a wide range of applications in the fields of immunological monitoring, vaccine trials, and the study of infectious diseases. This study aimed to prepare monoclonal antibodies against duck IFN-γ protein and to establish an ICS protocol for detecting the duck IFN-γ protein. The duIFN-γ-His or duIFN-γ-Fc gene was cloned into the pEE12.4 expression vector and expressed as a recombinant protein of size 20.2 KDa or 54.9 KDa in 293F cells. The purified recombinant proteins were inoculated into BALB/c mice to generate splenic lymphocytes capable of secreting anti-duIFN-γ antibodies, and hybridoma cells were obtained after fusion with SP2/0 cells. A new hybridoma cell line named 24H4, which stably secreted IgG3 κ subtype antibody against duck IFN-γ, was established. This monoclonal antibody (mAb) was identified by Western blot to recognize duck IFN-γ antibodies, and the indirect ELISA results showed that its ability to recognize IFN-γ protein reached 0.001 μg/mL. The established ICS method was used to stain PBMCs after Concanavalin A (ConA) stimulation, and duck IFN-γ protein was successfully detected by flow cytometry, indicating that the ICS method was successful. In this study, we provide a crucial tool for subsequent research on duck cellular immune responses by using the monoclonal antibody 24H4. Full article

Exosomes, spherical lipid-bilayered particles secreted by cells, have recently emerged as a novel and highly promising drug delivery system, attracting extensive attention in the field of biomedical research. Dendritic-cell-derived exosomes (DC-Exos) possess surface protein and ligands characteristic of DC cells, such as functional MHC-I and MHC-II, CD80, CD86. These components play a crucial role in immune responses, facilitating antigen uptake, presentation, and the activation of antigen-specific CD4 and CD8 T cells. These properties make them striking and excellent drug delivery vehicles for use in various immune diseases and cancer therapy. This review summarizes and discusses the characteristics, current methods and types of drug loading of DC-Exos. Its surface modifications and application in disease treatment were also discussed, aiming to motivate the development of exosome-based theranostic nanoplatforms and nanotechnology for improved healthcare treatments. Full article

Campylobacter is one of the leading bacterial causes of gastroenteritis worldwide. It frequently contaminates poultry and other raw meat products, which are the primary sources of Campylobacter infections in humans. Plasmids, known as important mobile genetic elements, often carry genes for antibiotic resistance, virulence, and self-mobilization. They serve as the main vectors for transferring genetic material and spreading resistance and virulence among bacteria. In this study, we identified 34 new plasmids from 43 C. jejuni and C. coli strains isolated from retail meat using long-read and short-read genome sequencing. Pangenomic analysis of the plasmid assemblies and reference plasmids from GenBank revealed five distinct groups, namely, pTet, pVir, mega plasmids (>80 kb), mid plasmids (~30 kb), and small plasmids (<6 kb). Pangenomic analysis identified the core and accessory genes in each group, indicating a high degree of genetic similarity within groups and substantial diversity between the groups. The pTet plasmids were linked to tetracycline resistance phenotypes in host strains. The mega plasmids carry multiple genes (e.g., aph(3’)-III, type IV and VI secretion systems, and type II toxin–antitoxin systems) important for plasmid mobilization, virulence, antibiotic resistance, and the persistence of Campylobacter. Together, the identification and comprehensive genetic characterization of new plasmids from Campylobacter food isolates contributes to understanding the mechanisms of gene transfer, particularly the spread of genetic determinants of virulence and antibiotic resistance in this important pathogen. Full article

Vibrio vulnificus is a significant opportunistic pathogen with the highest fatality rate among foodborne microbes. However, due to a lack of comprehensive surveillance, the characteristics of isolates in China remain poorly understood. This study analyzed 60 strains of V. vulnificus isolated from diverse sources in Shanghai, including shellfish, crabs, shrimps, throat swabs of migratory birds, as well as seafood farming water and seawater. Identification of the genotypes was performed using PCR, and cytotoxicity was determined using an LDH assay. DNA was sequenced using Illumina NovaSeq followed by a bioinformatic analysis. The results demonstrated that a majority of the strains belonged to the 16S rRNA B-vcgC genotype. All strains carried five antibiotic resistance genes (ARGs), with some strains carrying over ten ARGs, mediating resistance to multiple antibiotics. Five strains possessed a highly abundant effector delivery system, which further investigations revealed to be a type III secretion system II (T3SS2), marking the first description of T3SS2 in V. vulnificus. Phylogenetic analysis indicated that it belonged to a different genetic lineage from T3SS2α and T3SS2β of V. parahaemolyticus. Bacteria with T3SS2 sequences were concentrated in coastal areas and mostly within the genus Vibrio in the global prevalence survey. Our study provides essential baseline information for non-clinical V. vulnificus and discovers the existence of T3SS2 in several strains which may be more virulent, thereby posing a new threat to human health. Full article

Extensively drug-resistant P. aeruginosa (XDR-PA) has been highlighted as a serious public health threat. The present study aimed to explore the genomic characteristics of two Vietnamese extended-spectrum β-lactamase-9 (VEB-9)-producing XDR-PA isolates from Bulgaria in comparison to all bla_VEB-9-positive strains with available genomes. The isolates designated Pae51 and Pae52 were obtained from tracheobronchial aspirates of intensive care unit (ICU) patients. Antimicrobial susceptibility testing, whole-genome sequencing, RT-qPCR, and phylogenomic analysis were performed. Pae51 and Pae52 were resistant to most antipseudomonal β-lactams including carbapenems, aminoglycosides, and fluoroquinolones but remained susceptible to colistin and cefiderocol. Numerous resistance determinants were detected: bla_VEB-9, bla_PDC-3, bla_OXA-10, bla_OXA-50, aac(6′)-II, ant(2″)-Ia, ant(3″)-IIa, aph(3′)-IIb, cprP, catB7, dfrB2, sul1, fosA, and tet(A). Both isolates carried complex integrons with bla_VEB-9 and tet(A) embedded next to the conservative 3′ end sequences. A variety of virulence factors were also identified, including the type III secretion system exotoxin U. Pae51 and Pae52 differed by only four SNPs and belonged to the high-risk clone ST357. To our knowledge, this is the first report of bla_VEB-9-positive XDR-PA isolates in Bulgaria presenting a detailed genomic analysis. The development of novel antimicrobial strategies for such pathogens should be an essential part of infection control stewardship practices in ICU wards. Full article

Plesiomonas shigelloides, a Gram-negative bacillus, is the only member of the Enterobacteriaceae family able to produce polar and lateral flagella and cause gastrointestinal and extraintestinal illnesses in humans. The flagellar transcriptional hierarchy of P. shigelloides is currently unknown. In this study, we identified FlaK, FlaM, FliA, and FliA_L as the four regulators responsible for polar and lateral flagellar regulation in P. shigelloides. To determine the flagellar transcription hierarchy of P. shigelloides, the transcriptomes of the WT and ΔflaK, ΔflaM, ΔfliA, and ΔfliA_L were carried out for comparison in this study. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and luminescence screening assays were used to validate the RNA-seq results, and the Electrophoretic Mobility Shift Assay (EMSA) results revealed that FlaK can directly bind to the promoters of fliK, fliE, flhA, and cheY, while the FlaM protein can bind directly to the promoters of flgO, flgT, and flgA. Meanwhile, we also observed type VI secretion system (T6SS) and type II secretion system 2 (T2SS-2) genes downregulated in the transcriptome profiles, and the killing assay revealed lower killing abilities for ΔflaK, ΔflaM, ΔfliA, and ΔfliA_L compared to the WT, indicating that there was a cross-talk between the flagellar hierarchy system and bacterial secretion system. Invasion assays also showed that ΔflaK, ΔflaM, ΔfliA, and ΔfliA_L were less effective in infecting Caco-2 cells than the WT. Additionally, we also found that the loss of flagellar regulators causes the differential expression of some of the physiological metabolic genes of P. shigelloides. Overall, this study aims to reveal the transcriptional hierarchy that controls flagellar gene expression in P. shigelloides, as well as the cross-talk between motility, virulence, and physiological and metabolic activity, laying the groundwork for future research into P. shigelloides’ coordinated survival in the natural environment and the mechanisms that infect the host. Full article

Coxiella burnetii is an obligate intracellular Gram-negative bacterium that causes Q fever, a life-threatening zoonotic disease. C. burnetii replicates within an acidified parasitophorous vacuole derived from the host lysosome. The ability of C. burnetii to replicate and achieve successful intracellular life in the cell cytosol is vastly dependent on the Dot/Icm type 4B secretion system (T4SSB). Although several T4SSB effector proteins have been shown to be important for C. burnetii virulence and intracellular replication, the role of the icmE protein in the host–C. burnetii interaction has not been investigated. In this study, we generated a C. burnetii Nine Mile Phase II (NMII) mutant library and identified 146 transposon mutants with a single transposon insertion. Transposon mutagenesis screening revealed that disruption of icmE gene resulted in the attenuation of C. burnetii NMII virulence in SCID mice. ELISA analysis indicated that the levels of pro-inflammatory cytokines, including interleukin-1β, IFN-γ, TNF-α, and IL-12p70, in serum from Tn::icmE mutant-infected SCID mice were significantly lower than those in serum from wild-type (WT) NMII-infected mice. Additionally, Tn::icmE mutant bacteria were unable to replicate in mouse bone marrow-derived macrophages (MBMDM) and human macrophage-like cells (THP-1). Immunoblotting results showed that the Tn::icmE mutant failed to activate inflammasome components such as IL-1β, caspase 1, and gasdermin-D in THP-1 macrophages. Collectively, these results suggest that the icmE protein may play a vital role in C. burnetii virulence, intracellular replication, and activation of inflammasome mediators during NMII infection. Full article

Wolbachia, a group of Gram-negative symbiotic bacteria, infects nematodes and a wide range of arthropods. Diaphorina citri Kuwayama, the vector of Candidatus Liberibacter asiaticus (CLas) that causes citrus greening disease, is naturally infected with Wolbachia (wDi). However, the interaction between wDi and D. citri remains poorly understood. In this study, we performed a pan-genome analysis using 65 wDi genomes to gain a comprehensive understanding of wDi. Based on average nucleotide identity (ANI) analysis, we classified the wDi strains into Asia and North America strains. The ANI analysis, principal coordinates analysis (PCoA), and phylogenetic tree analysis supported that the D. citri in Florida did not originate from China. Furthermore, we found that a significant number of core genes were associated with metabolic pathways. Pathways such as thiamine metabolism, type I secretion system, biotin transport, and phospholipid transport were highly conserved across all analyzed wDi genomes. The variation analysis between Asia and North America wDi showed that there were 39,625 single-nucleotide polymorphisms (SNPs), 2153 indels, 10 inversions, 29 translocations, 65 duplications, 10 SV-based insertions, and 4 SV-based deletions. The SV-based insertions and deletions involved genes encoding transposase, phage tail tube protein, ankyrin repeat (ANK) protein, and group II intron-encoded protein. Pan-genome analysis of wDi contributes to our understanding of the geographical population of wDi, the origin of hosts of D. citri, and the interaction between wDi and its host, thus facilitating the development of strategies to control the insects and huanglongbing (HLB). Full article