Search Results (2,018)

Yellow fever remains a significant public health concern in endemic regions of South America and Africa, where periodic outbreaks continue to challenge surveillance and control efforts. Despite the widespread use of vaccines and historical YFV strains in experimental settings, there is limited information on the pathogenic behavior of contemporary wild-type isolates in animal models. To address this gap, this study aimed to develop and characterize a murine model infected with a wild-type YFV strain isolated in 2018, from Brazil’s largest sylvatic outbreak in decades. In this study, four-week-old male and female C57BL/6 IFNAR1^−/− mice were subcutaneously infected with WT YFV. Mice exhibited a nearly 50% survival rate and developed several clinical signs. Viral loads were assessed in serum and some tissues, collected either upon euthanasia of moribund animals or at the end point. YFV RNA was detected in all sampled tissues and serum. Infectious viral particles were identified in the brains of both sexes and in the testis. No statistically significant differences were observed between males and females in survival, clinical signs, or viral loads. Altogether, this study provides a robust and reproducible murine model for wild-type YFV infection, offering a valuable platform for investigating viral pathogenesis, host responses, and potential therapeutic interventions. Full article

The bacterial flagellum plays a crucial role in pathogenesis. However, the mechanism by which the flagellum interferes with host energy metabolism remains unclear. In this study, we confirmed that deletion of the fliC gene resulted in a 30% reduction in the virulence of Pseudomonas plecoglossicida against the large yellow croaker (Larimichthys crocea). Compared to the wild-type strain (WT) infection group, the ΔfliC infection group exhibited a 29.54% decrease in the number of vacuolar degeneration hepatocytes and a 50.83% higher liver glycogen content. Furthermore, infection led to decreased mitochondrial complex V activity, a reduced NAD+/NADH ratio, lower levels of reduced glutathione (GSH), and increased lipid peroxide levels; however, these metabolic perturbations were significantly ameliorated in the ΔfliC group compared to the WT group. Proteomic analysis revealed that the dysregulation of the complement cascade and core carbon metabolic pathways observed in the WT infection group liver was significantly alleviated in the ΔfliC infection group. Additionally, in the ΔfliC infection group, pro-inflammatory genes (such as Tlr5, Tnfα, and Il1β) were downregulated, while lipid metabolism-related genes (such as Acox1, Cpt1a, and Pparα) were upregulated, suggesting the suppression of the Tlr5/NF-κB immune signaling axis and enhanced fatty acid β-oxidation. Collectively, fliC may mediate the disruption of host glucose and lipid metabolism homeostasis through a Tlr5-triggered immunometabolic regulatory axis. In conclusion, this study demonstrates that bacterial flagella modulate host energy metabolism, expanding our understanding of flagellum-mediated pathogenesis. Full article

Background/Objectives: Some marine plants and algae are known to exert health benefits. However, the long-term effects and underlying mechanisms of these health benefits are still poorly understood. For this reason, we have investigated an extract from the marsh samphire Salicornia europaea for its life-prolonging potential. Methods: We investigated the effect of an aqueous extract of Salicornia europaea (SEE) on the lifespan of several wild-type strains of Drosophila. In addition, we used deficient flies to elucidate the mechanism of the life-prolonging effects. Finally, we comprehensively phenotyped the treated animals. Results: Supplementing a standard diet with SEE extended the lifespan of different Drosophila laboratory strains by up to a third (37% in w¹¹¹⁸ and 19% in yw). A total of 0.05% of SEE were ineffective, whereas 0.2% induced robust lifespan prolongation. This effect was strictly sex-specific, as the SEE application was completely ineffective in males, while prolonging life in females. We found that the body fat content of SEE-treated female flies was lower compared to controls. The extract also positively impacted the lifespan of flies fed a high-fat diet but not a high-sugar diet. SEE exhibited a lipase-inhibitory activity in vitro. Moreover, SEE counteracted aging-associated loss of intestinal barrier integrity. The sex-specific lifespan extensions induced by the SEE entirely depended on functional Tor signaling in the flies. Tissue-specific silencing of the Tor signaling pathway in different cellular compartments of the intestine reduced, but did not altogether abolish, the lifespan-prolonging effect in females. Conclusions: SEE is a promising candidate for a health-promoting intervention, as it induces lifespan-prolonging and anti-obesogenic effects in a sex-specific manner. These effects depend on functional Tor and partially on FoxO signaling. Future studies should identify the active compounds in the extract. Full article

Background: Uropathogenic Escherichia coli (UPEC) is the number one cause of urinary tract infections (UTIs) in humans. The ability to bind to uroepithelial cells through type 1 pili and ascend the urinary tract via flagella is important in the early stages of a UTI. However, both type 1 pili and flagella can also target the bacteria for elimination via monocytes/macrophages later in a UTI. We hypothesized that the loss of both type 1 pili and flagella on the UPEC cells would make them less likely to be phagocytized by phagocytic cells. Methods: In this study, ΔfimA, ΔfliC, and ΔfimA ΔfliC mutants were compared to the wild type UPEC strain NU149 in phagocytosis assays using human and murine monocytic cell lines. Results: A ΔfimA ΔfliC double mutant was phagocytized significantly less than the wild type strain. Conclusion: The data show that the loss of both type 1 pili and flagella expression on the UPEC cells reduces phagocytosis of the bacteria by human and murine monocytes. Although type 1 pili and flagella are important for establishing a UTI and ascension into the kidneys, the loss of these proteinaceous structures may allow the UPEC cells to evade the innate immune defenses in certain environments within the human body. Full article

Whole-genome sequence (WGS) analysis was used in this study to characterize Shiga toxin-producing Escherichia coli (STEC) isolates in free-ranging red deer from the central Italian Alps. Fecal samples from 92 hunted red deer collected between September and December 2022 were analyzed for the presence of STEC. Single E. coli colonies positive by PCR for stx genes were analyzed by WGS. STEC were isolated from eleven (12%) samples, showing eight stx2b, one stx2a, two stx1c, and one stx1a subtypes. Different serotypes and sequence types were identified (n = 8 each). Three isolates of O27:H30 serotype and ST753 showed no correlation in the cgMLST analysis (AD range 44–98). All strains harbored additional virulence factors. The only isolate harboring stx2a also possessed the eae gene and belonged to serotype O26:H11. Some isolates displayed shuffled virulence features of more than one E. coli pathotype. The high genetic diversity of strains circulating in the red deer population living in the central Italian Alps, including the STEC O26:H11 strain associated with STEC from severe disease in humans, confirms red deer as STEC reservoirs and highlights the need for monitoring the presence of these pathogens in wild ruminants. Full article

Background/Objectives: Aeromonas veronii is a significant pathogen affecting aquatic animals and has the potential to infect humans. Vaccination remains the most effective strategy for preventing infections caused by this bacterial strain. Methods: This study aimed to validate the efficacy of bacterial ghosts as an oral vaccine by administering them to Cyprinus carpio and evaluating the resultant innate and acquired immune responses. Following immunization, the vaccinated Cyprinus carpio were exposed to a lethal dose of the wild-type bacterial strain to assess survival rates and relative protection efficiency. Results: Oral vaccination with bacterial ghosts led to the significant enhancement of lysozyme (LZM) and myeloperoxidase (MPO) activity in koi serum. It also resulted in the upregulation of cytokines, such as IL-2 and TNF-α, as well as an increase in both systemic (IgM) and mucosal (IgZs) antibody responses. The immunized group demonstrated reduced cumulative mortality following bacterial challenge. The relative percent survival in the vaccinated group reached as high as 87.50%. Conclusions: The oral immunization of Cyprinus carpio with A. veronii-derived bacterial ghosts confers substantial immune protection, providing a foundational basis for the development of novel vaccines against A. veronii. Full article

Plant parasitic nematodes are a significant agricultural threat, causing substantial economic losses. Methyl bromide, a commonly used nematicide, has been banned due to its harmful environmental and human health effects. As an alternative, the expression of the programmed cell death (PCD) gene CED4 from Caenorhabditis elegans in transgenic plants has been proposed to control nematode populations. In this study, the interaction between CED4 and other proteins was analyzed, and peptide sequences representing interaction domains were identified. Efficacy assays demonstrated that specific peptides—particularly Peptides 2 and 3 (N-terminal α/β domain) and Peptide 12 (C-terminal HD-2 domain)—induced significant mortality in C. elegans, while other peptides were ineffective. The study further investigated whether these peptides, along with modified CED4-like peptides (2a, 3a, and 12a), induce PCD in C. elegans via the activation of the nematode’s endogenous PCD pathway. Testing was conducted on wild-type and mutant strains of C. elegans (ced-4 and ced-3 mutants). Nematode survival was monitored over 34 days, revealing that c3 mutants survived exposure to CED4-like peptides, suggesting that the peptides trigger PCD through the activation of the endogenous cell death pathway. These findings support the potential use of CED4-based peptides as a novel strategy for nematode control. Full article

The municipalities of Peixe-Boi and Santa Bárbara do Pará, both in the Pará State (eastern Amazon), have more than half of their territory deforested. Understanding the viral diversity in wildlife that inhabits the surroundings of human communities contributes to strengthening surveillance. Samples from eleven bats, seven opossums, and eight rodents from the two locations were screened by high-throughput sequencing for virome analysis. Viral reads were assigned into twenty viral families, from which the most abundant was Retroviridae. Host order, tissue type, and season showed a significant effect on viral composition. Five viral genomes of bat ERVs with intact genes were recovered, showing the need to understand their endogenous nature. In addition, a new Buritiense virus (Hantaviridae) strain was also obtained, supporting its circulation in Santa Bárbara do Pará and expanding its genomic information. Together, these findings reinforce the need for continuous surveillance in wild animals, especially in the Amazon region, to anticipate potential threats to public health. Full article

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to evolve, with mutations leading to the emergence of new variants. JN.1, a subvariant of omicron BA.2.86, has demonstrated marked immune escape and is now included in updated vaccine formulations. While reduced sensitivity has been reported for antibody assays using ancestral spike protein subunits to detect omicron-induced responses, the performance of full-length spike-based assays against omicron sublineages remains unclear. We aimed to compare the sensitivity of ELISA and Luminex assays using full-length spike proteins from the ancestral Wuhan strain and the JN.1 variant. Methods: Wuhan and JN.1 full-length spike protein constructs were designed and expressed in Expi293F mammalian cells. In-house ELISAs based on previously validated protocols were used to measure anti-spike IgG levels. Additionally, a Luminex-based assay for anti-spike antibody detection was developed and validated. Both assays were applied to the following sample groups: pre-pandemic samples (designated “gold standard negatives”); PCR confirmed 2020 positives (“gold standard wildtype positives”); PCR confirmed 2024 positives (“gold standard omicron positives”); 2022 vaccinated individuals with verbal confirmed infection (“gold standard hybrid positives”); and 2024 household samples (“unknowns”). Results: Wuhan spike protein showed a sensitivity of 100% (95% CI: 0.88–1.0) in detecting omicron-specific antibodies using gold standard omicron positives with JN.1 spike protein as a reference assay. Overall, across all samples, in ELISA, the Wuhan antigen had a sensitivity of 0.93 (95% CI: 0.89–0.95) and a specificity of 0.98 (95% CI: 0.94–0.99). The JN.1 antigen showed a sensitivity of 0.91 (95% CI: 0.87–0.94) and a specificity of 0.97 (95% CI: 0.93–0.99). In Luminex, sensitivity was 0.95 (95% CI: 0.91–0.97) for Wuhan and 0.94 (95% CI: 0.91–0.96) for JN.1. Specificity for both antigens in Luminex was 0.98 (95% CI: 0.94–0.99). Conclusions: Both ELISA and Luminex assays showed comparable sensitivity and specificity for both Wuhan and JN.1 antigens, indicating that mutations in the JN.1 variant do not significantly impact assay performance. This suggests preserved antigenic recognition across variants. Full article

Salmonella enterica subsp. enterica serovar Typhimurium is a major foodborne pathogen whose ability to form biofilms contributes to persistent contamination in food-processing and clinical environments. This study investigated the anti-biofilm activity of the biosurfactant surfactin, produced by Bacillus subtilis, against S. Typhimurium wild type (LT2) and its lipopolysaccharide (LPS)-modified mutants on commonly used plastic surfaces such as polypropylene (PP) and polystyrene (PS). Biofilm formation was quantified using the crystal violet assay, revealing significantly higher biomass on PS compared to PP (p < 0.0001). Surfactin at 5 µg/mL was identified as the minimum biofilm inhibitory concentration (MBIC), significantly reducing biofilm formation in the wild-type and LPS mutants rfaL, rfaJ, rfaF (all p < 0.0001), and rfaI (p < 0.01). Further analysis using fluorescence microscopy and SYPRO^® Ruby staining confirmed a significant reduction in extracellular polymeric substances (EPSs) on PP surfaces following surfactin treatment, particularly in strains LT2 (p < 0.0001), rfa (p < 0.01), rfaL (p < 0.0001), rfaG (p < 0.05), and rfaE (p < 0.0001). These findings highlight the influence of LPS structure on biofilm development and demonstrate surfactin’s potential as an eco-friendly antimicrobial agent for controlling S. Typhimurium biofilms on food-contact surfaces. Analysis of mutants revealed that disruption of the rfa gene, which is involved in the biosynthesis of the outermost region of the lipopolysaccharide (LPS), significantly reduced bacterial attachment to polypropylene. This suggests that interactions between the external LPS layer and the plastic surface are important for colonisation. In contrast, mutants in core LPS biosynthesis genes such as rfaE and rfaD did not show any notable differences in attachment compared to the wild-type strain. This highlights the specific importance of outer LPS components, particularly under surfactant conditions, in mediating interactions with plastic surfaces. This work supports the application of biosurfactants in food safety strategies to reduce the risk of biofilm-associated contamination. Full article

Copper contamination in the environment poses significant risks to both soil and human health, making the need for reliable monitoring methods crucial. In this study, we report the use of the EmStat Pico module as potentiostat to develop a portable electrochemical biosensor for copper detection, utilizing yeast Saccharomyces cerevisiae cells immobilized on a polydopamine (PDA)-coated screen-printed electrode (SPE). By optimizing the sensor design with a horizontal assembly and the volume reduction in the electrolyte solution, we achieved a 10-fold increase in current density with higher range of copper concentrations (0–300 µM CuSO₄) compared to traditional (or previous) vertical dipping setups. Additionally, the use of genetically engineered copper-responsive yeast cells further improved sensor performance, with the recombinant strain showing a 1.7-fold increase in current density over the wild-type strain. The biosensor demonstrated excellent reproducibility (R² > 0.95) and linearity over a broad range of copper concentrations, making it suitable for precise quantitative analysis. To further enhance portability and usability, a Bluetooth-enabled electrochemical platform was integrated with a web application for real-time data analysis, enabling on-site monitoring and providing a reliable, cost-effective tool for copper detection in real world settings. This system offers a promising solution for addressing the growing need for efficient environmental monitoring, especially in agriculture. Full article

Fusarium crown rot, a widespread and destructive disease affecting cereal crops (particularly wheat and barley), is primarily caused by the soil-borne fungal pathogen Fusarium pseudograminearum. Secondary metabolites (SMs) play a crucial role in colonization and host tissue invasion by pathogenic fungi. In this study, we investigated the functional role of FpTox2, a secondary metabolite-related gene in F. pseudograminearum. An FpTox2 deletion mutant exhibited significantly reduced radial growth compared to wild-type F. pseudograminearum. Notably, the mutant strain completely lost conidiation capacity under induced conditions. Furthermore, although it showed decreased sensitivity to the cell membrane inhibitor sodium dodecyl sulfate (SDS), the mutant demonstrated enhanced susceptibility to NaCl, a metal ion stressor. Most importantly, the pathogen’s virulence was markedly attenuated in wheat stem base infections following FpTox2 deletion, and we demonstrated that FpTox2 regulates pathogen virulence by influencing deoxynivalenol production. In conclusion, FpTox2 is crucial for vegetative growth, asexual development, abiotic stress responses, and full virulence in F. pseudograminearum. Full article

Ganoderic acid (GA) is a key bioactive component with pharmacological properties that is found in Ganoderma lingzhi, a renowned medicinal mushroom. Currently, the regulatory mechanisms underlying GA biosynthesis in G. lingzhi remain to be further elucidated. In this study, blue light induction was found to significantly enhance the GA content in G. lingzhi. To explore the regulatory mechanism of GA biosynthesis in response to blue light, the blue light receptor WC-2 was identified, and its regulatory role was characterized. The deletion of wc-2 resulted in a significant reduction in both GA content and the accumulation of intermediates compared to the wild-type control strain, largely due to the strong downregulation of key GA biosynthetic genes. Additionally, decreased asexual spore production and reduced expression of sporulation-specific genes were observed with the deletion of wc-2. The overexpression of wc-2 led to greatly enhanced GA accumulation. Under blue light induction, the maximum contents of GA-Mk, GA-T, GA-S, and GA-Me were 2.27-, 2.51-, 2.49-, and 2.08-fold higher, respectively, compared to the control kept in darkness. These results demonstrate that the blue light receptor WC-2 functions as a positive regulator of GA biosynthesis in G. lingzhi, influencing the expression of genes involved in GA biosynthesis and asexual spore production, thereby advancing our understanding of the intricate regulatory network of GA biosynthesis. Full article

The velvet complex is a master regulator of multiple physiological processes in filamentous fungi. In this study, we characterized the functions of velvet gene FpvelC in Fusarium proliferatum, which was the causative agent of rice spikelet rot disease. Compared with the wild-type Fp9 strain, deletion of FpvelC hindered conidiation, leading to a low level of trehalose content but excessive accumulation of chitin in conidia. Lack of FpvelC resulted in increased sensitivity to oxidative stress and decreased expression of antioxidant genes. Notably, ΔFpvelC exhibited attenuated pathogenicity on rice and maize, failure to produce invasive hyphae, and downregulation of genes encoding xylanases and xyloglucanases during infection processes. Nevertheless, disruption of FpvelC enhanced production of fumonisin B1 (FB1) and fusaric acid concomitantly; transcripts of the clustering genes responsible for the two mycotoxins’ biosynthesis were significantly increased. Additionally, the absence of FpvelC was displayed as more sensitive to rapamycin than the Fp9 strain, accompanied with less intracellular glutamine. Overall, FpvelC played versatile roles in conidiation, response to oxidative stress, pathogenicity and mycotoxins production in F. proliferatum. Full article

Background: Tuberculosis (TB) remains a primary global health concern, despite the widespread availability of effective chemotherapeutic interventions. The emergence and dissemination of drug-resistant strains of Mycobacterium tuberculosis, particularly those exhibiting resistance to rifampicin, present significant obstacles to the success of TB control programs. Consequently, there is an urgent need for rapid, sensitive, and specific molecular diagnostic tools to inform timely clinical decision-making and reduce the transmission of disease. Loop-mediated isothermal amplification (LAMP) has gained attention as a promising alternative to conventional polymerase chain reaction (PCR) techniques. This method, which facilitates DNA amplification under constant temperature conditions, offers advantages including high specificity, rapid turnaround time, and operational simplicity—features that render it especially suitable for implementation in resource-limited settings. Methods: In this study, a LAMP assay targeting the rpoB gene was developed, with particular focus on detecting the codon 531 C→T mutation associated with rifampicin resistance. A set of four to six primers was designed to recognize six distinct regions of the target sequence. Allele-specific amplification was achieved by incorporating a deliberate single nucleotide mismatch at the 3′ terminus of the B2 primer to enable precise discrimination between wild-type and mutant alleles. The assay was conducted at an optimized temperature of 61 °C for 60 min, followed by visual detection using a lateral flow dipstick (LFD) within five minutes. Results: The LAMP-LFD assay demonstrated 100% concordance with drug susceptibility testing (DST) and DNA sequencing. No cross-reactivity with wild-type strains was observed, underscoring the assay’s high specificity. Conclusions: This platform offers a robust, field-deployable solution for detecting the codon 531 C→T mutation associated with rifampicin resistance in low-resource settings. Full article