Microbial pathogenesis最新文献

Infectious Bronchitis (IB) is an acute contagious disease of poultry caused by the infectious bronchitis virus (IBV), genus Gammacoronavirus of the family Coronaviridae. The objective of this study was to characterize the genotypic and pathological features of IBV circulating in chickens in major poultry-producing states of India from 2022-2024. A total of 1685 representative carcasses from 272 IB-suspected flocks were examined with the help of conventional and advanced diagnostic techniques. All the flocks under study were vaccinated with live/inactivated IB vaccines. A total of 33 flocks (12.2%) out of 272 showed PCR positivity for IBV. A total of 22 field isolates were successfully adapted in embryonated chicken eggs. Clinical signs, gross and histopathological lesions relevant to a respiratory/renal/reproductive system ailment were apparent in all IB cases. Thirty selected S1 gene PCR products were sequenced, and phylogenetic analysis revealed that all the study sequences were clustered with the Genotype I-1 (GI-1). Three consistent mutations were identified in the S1 protein from Northern India isolates: Ile131Leu, Asn306Asp, and Gly376Arg. Similarly, all the IBV isolates from Southern India had a consistent Glu179Ala substitution. S1 epitope analysis predicted one amino acid variation in a potential linear B-cell epitope in the IBV 376Arg variant, located within HVR3, alters the local charge, which may potentially influence antigenicity and vaccine efficacy, however confirmation will require neutralization assays and reverse-genetics experiments. This comprehensive study provides valuable insights into IBV evolution and its implications for disease control in the Indian poultry sector.

Background: Xin-Jia-Tong-Xie-Yao-Fang (XJTXYF) is a proven prescription for managing diarrhea-predominant irritable bowel syndrome (IBS-D), which is a prevalent functional gastrointestinal disorder. However, the underlying mechanism of XJTXYF remains unclear. This study aims to explore the material basis and potential mechanisms of XJTXYF against IBS-D.

Methods: The constituents of XJTXYF were identified by UPLC-Q-TOF-MS/MS, and potential targets and pathways were screened by network pharmacology. Changes in the intestinal microbiome and fecal butyric acid levels after XJTXYF administration were analyzed through 16S rRNA sequencing and HPLC respectively. The abdominal withdrawal reflex score, serum levels of FITC-D and the expression of intestinal epithelial tight junction proteins, as well as the activity of the PI3K/Akt pathway were assessed. In-vitro experiments involved silencing GPR109A using small interfering RNA and inducing barrier damage with LPS pre-treatment in the Caco-2 cell line. Barrier function was evaluated by FITC-D permeability and tight junction protein expressions. The activity of the PI3K/Akt pathway was determined through Western blotting analysis.

Results: The major active compounds of XJTXYF identified by UPLC-Q-TOF-MS/MS include Saikosaponin C, Hesperetin, Neohesperidin, Albiflorin, Quercetin and so on. The PI3K/Akt signaling pathway was predicted by network pharmacology as a potential target of XJTXYF in treating IBS-D. Animal experiments demonstrated that XJTXYF could increase body weight, improve visceral hypersensitivity, rebalance gut flora dysbiosis and upregulate fecal butyric acid content in IBS mice. The XJTXYF also showed the abilities of intestinal barrier repairment and PI3K/Akt pathway suppression. Fecal microbiota transplantation and the positive controls (NaB and Clostridium Butyricum) verified that a causal relationship existed between gut microbiome changes and IBS-D improvement after XJTXYF treatment. In-vitro experiments revealed the role of butyrate in barrier protection via PI3K/Akt inhibition.

Conclusion: Overall, in this study, we revealed that XJTXYF could restore intestinal barrier function through microbial butyrate mediated PI3K/Akt inhibition and improve IBS-D symptoms.

Proteus mirabilis is a uropathogen frequently implicated in catheter-associated urinary tract infections (CAUTIs), largely due to its ability to form biofilms and express multiple virulence factors. The limitations of conventional antibiotics, along with increasing resistance rates, necessitate the exploration of natural compounds with broader antimicrobial mechanisms against such pathogens. This study investigated the antibiofilm and anti-virulence potential of Juglone, a phytochemical derived from Juglans regia, against P. mirabilis. A series of in vitro assays demonstrated that Juglone not only inhibited bacterial proliferation in a dose- and time-dependent manner but also significantly restricted biofilm formation, as visualized by FE-SEM, while simultaneously impairing motility and reducing the secretion of critical virulence-associated enzymes. Membrane depolarization and altered membrane fluidity indicated compromised bacterial envelope integrity. Gene expression analysis using RT-qPCR further revealed the downregulation of multiple adherence- and virulence-associated genes. Complementing these findings, molecular docking and molecular dynamics simulations confirmed stable interactions between Juglone and the MrpH adhesin protein, highlighting its potential to interfere with host attachment mechanisms. Importantly, untargeted LC-MS-based metabolomic profiling revealed widespread metabolic reprogramming in Juglone-treated P. mirabilis, characterized by enhanced oxidative stress, redox imbalance, and suppression of core biosynthetic and energy-generating pathways. Taken together, these findings establish Juglone as a promising multi-target antimicrobial agent against P. mirabilis, with potential applications in the prevention of catheter-associated infections.

Aim of the study: The aim of this study was to characterise the volatile compounds of Juniperus phoenicea L. essential oil, to evaluate its antibacterial and antifungal properties and to explore its potential interaction with sodium chloride.

Materials and methods: Essential oil was extracted from Juniperus phoenicea L. by hydrodistillation, and volatile compounds were analysed by headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) to determine its composition. Agar-based disc diffusion and broth dilution methods were used to evaluate the antimicrobial activity of extracted oils. In addition, the impact of different sodium chloride concentrations in conjunction with the essential oil was assessed to determine their effect on microbial inhibition.

Results: The major volatile compounds of J. phoenicea were α-pinene (26.09%), γ-elemene (7.84%), α-copaene (7.68%), terpinyl acetate (6.65%), trans-caryophyllene (6.48%), δ-cadinene (6.4%), and α-humulene (5.04%). The antimicrobial activity of juniper EO was evaluated using the disc diffusion method. The EO exhibited antibacterial and antifungal activity, with inhibition zones ranging from 9 to 25 mm for four pathogenic bacteria (E. faecalis, E. coli, S. aureus, and L. monocytogenes); in contrast, K. pneumoniae showed complete resistance to the EO, with no detectable inhibition zone (0 mm), and between 8 and 25 mm for four fungi (Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, and Trichoderma sp.). The MBC/MIC and MFC/MIC ratios indicated that the essential oil exhibited bactericidal and fungicidal activity against the tested microbial strains. The MIC values ranged from 1.56 to 3.12 μL/mL for bacteria and from 12.5 to 100 μL/mL for fungi, while MBC values ranged from 3.12 to 6.25 μL/mL and MFC values from 25 to 100 μL/mL. The use of salt doses over 4 to 10% for bacteria and over 5 to 15% for fungi potentiated the inhibition effects, except for S. aureus, which showed salt tolerance.

Conclusions: Our findings indicate that juniper EO with sodium chloride possesses high antibacterial and antifungal activities, which render it a potent traditional remedy for preparing 'Djeld of Bouhezza'.

Non-typhoidal Salmonella (NTS), a zoonotic pathogen, is associated with food-borne illness in humans. Contaminated food such as milk and meat are major reservoir of Salmonella enterica, which is associated with salmonellosis in humans. In this work, we isolated and characterized a broad-spectrum lytic bacteriophage (fBSPA4) from chicken intestine that inhibits the growth of antibiotic resistance NTS isolates from several Indian poultry farms. fBSPA4 shows large burst size, a very short latent period, a strong tolerance to high temperatures (5-65 °C) and unnatural pH (3.0-11.0). Transmission electron microscopy (TEM) revealed that phage fBSPA4 possesses an icosahedral head (77 nm in diameter) and non-contractile tail (120 nm), characteristic of members of the class Caudoviricetes. Genome sequencing revealed a single contig of 87,179 base pairs with G+C content of 38.91%. The fBSPA4 has 123 codon-determining sequences (CDS) that are devoid of detrimental genes related to lysogeny, antibiotic resistance, virulence factors, or toxins. Further, ex vivo infection model showed that fBSPA4 significantly decreased Salmonella enterica levels in the buttermilk and yoghurt. In summary, this research highlights the potential use of fBSPA4 as a biocontrol agent to prevent contamination in milk products.

Background and aim: Rabies remains a major public health and veterinary concern worldwide, underscoring the need for improved vaccine immunogenicity. Nanomaterials are being looked at for their role in shaping early immune reactions, along with boosting targeted responses to antigens. In this work, particles made of cerium were tested as possible helpers in a vet-approved dead rabies vaccine using mice. Using a method that formed cerium oxide nanoparticles, scientists checked how they looked and behaved. These tiny particles were tested to understand their makeup plus shape.

Materials and methods: CeNPs were synthesized and characterized for their physical and chemical properties. Subsequently, a mouse model using a standard veterinary rabies vaccine was evaluated for its capacity to elicit a booster response. Animals were immunized with inactivated rabies vaccine formulations with or without CeNPs, and immune responses were assessed by rabies virus neutralizing antibody (RVNA) titers (RFFIT) and serum cytokine levels (IL-4 and IFN-γ).

Results: The Rapid Fluorescent Focus Inhibition Test (RFFIT) revealed that NAb titers in the primary cohort (CRV-CeNPs) showed greater variability than those in the reference cohorts (A and B) (P < 0.001). A marked distinction was observed in the levels of interleukin-4 (IL-4) and Interferon gamma (IFN-γ) within the primary cohort (CRV-CeNPs) in contrast to the reference cohorts (P ≤ 0.05).

Conclusion: CeNP co-formulation was associated with higher RVNA titers than vaccine alone and modulated systemic cytokine levels. Within the scope of this study, CeNPs demonstrate adjuvant-like activity in an inactivated veterinary rabies vaccine formulation. Safety conclusions are limited to clinical monitoring and survival outcomes; mechanistic and histopathological assessments warrant further dedicated studies.

Antifungal resistance is an emerging global health concern, particularly in opportunistic fungal pathogens like Candida. While environmental factors such as atmospheric temperature fluctuations have been linked to antimicrobial resistance in bacteria, their impact on fungal resistance remains underexplored. This study investigates the relationship between atmospheric temperature variations and antifungal resistance as well as virulence factors in Candida isolated from a forest ecosystem. A total of 30 fecal samples were collected from the Margalla Hills region, and Candida isolates were identified using culture-based and biochemical assays. Antifungal susceptibility was assessed using the Kirby-Bauer disk diffusion method, testing the efficacy of amphotericin B, fluconazole, ketoconazole, and voriconazole. Biofilm formation was analyzed using the Congo Red Assay, while enzymatic virulence factors (phospholipase and esterase activity) were evaluated using Tween-80 and egg yolk media, respectively. The results revealed a significant temperature-dependent increase in resistance to different antifungals. Biofilm formation was also significantly influenced by temperature, whereas phospholipase and esterase activities showed no meaningful variation. Statistical analysis indicated weak but positive correlations between temperature and resistance as well as biofilm formation, but not statistically significant. These findings suggest that rising global temperatures could contribute to increased antifungal resistance and enhanced biofilm formation in Candida, potentially making infections more persistent and difficult to treat. The stability of phospholipase and esterase activity indicates that not all virulence factors are temperature-sensitive, emphasizing the complexity of fungal adaptation. This study highlights the critical need for further research on the influence of climate change on fungal pathogenicity and treatment efficacy.

Monkeypox is a zoonotic disease caused by the monkeypox virus (MPXV), which has garnered significant attention due to its global spread since its identification in 1970. In recent years, there has been a notable increase in cases outside Africa, particularly in 2022, when the World Health Organization (WHO) declared it a public health emergency. The clinical presentation of monkeypox resembles that of smallpox, although it is atypical, especially concerning the sexually transmitted patterns that have prompted extensive academic investigation. MPXV primarily spreads through direct contact with the skin lesions, bodily fluids, or respiratory secretions of infected individuals, with a significant increase in transmission observed within the men who have sex with men (MSM) community. The transmission capability of MPXV is closely linked to its genetic variability, particularly in the context of globalization and ecological changes. Additionally, the host's immune response plays a crucial role in controlling the infection, as MPXV employs various mechanisms to evade immune surveillance, MPXV infection can also be prevented through research into vaccines,thereby enhancing its survival capacity. Although progress has been made in developing antiviral drugs for MPXV, there remains a lack of specific effective treatments. Therefore, rapid drug development for mutations in MPXV is essential.

Inflammation serves as a crucial feedback mechanism in response to external stimuli, with severe inflammatory reactions leading to significant damage in the body. Evidence indicates that Lactobacillus plantarum can suppress inflammatory responses, effectively maintaining intestinal balance and stability, and are widely used in pig farming. Prebiotics, when compared to live bacteria, demonstrate a more pronounced probiotic function. In this study, lipopolysaccharides (LPS) was utilized as a stimulus for an inflammation model. Through in vitro cell experiments and in vivo pig trials, it was observed that oral administration of Lactobacillus plantarum prebiotics effectively inhibited inflammation. Moreover, the anti-inflammatory effect was improved with higher doses of prebiotics, without any observed intestinal damage. Additionally, flow cytometry analysis of peripheral blood mononuclear cells (PBMCs) and Peyer's patches (PPs) revealed alterations in various immune cell populations, including T cells, B cells, dendritic cells (DCs), and natural killer (NK) cells. Overall, the results showed an increase in T cell proportion during inflammation and a decrease upon resolution. B cells and DCs were suppressed during both inflammation and recovery periods. NK cells were unaffected by inflammation but their proportion decreased during the recovery phase. This study, for the first time, highlights that while Lactobacillus plantarum prebiotics alleviate clinical symptoms of inflammation, immune responses involving B cells and DCs are also suppressed, in addition to T cell immune responses. This finding not only enhances our understanding of the mechanisms of action of Lactobacillus plantarum prebiotics but also provides fundamental data for future therapeutic interventions and immunological applications.

Rho-associated kinase 1 (ROCK1) is a host kinase involved in the regulation of cytoskeletal dynamics, vesicle trafficking, and cell cycle control; however, its role in parvoviral infection remains largely unexplored. Building on our previous finding that minute virus of canines (MVC) activates the ROCK1/MLC2 signaling pathway to disrupt tight junction integrity and expose the Occludin coreceptor, we further investigated the role of ROCK1 signaling in MVC entry and replication. We demonstrate that ROCK1 exerts distinct, stage-specific roles during MVC infection. At the early stage of MVC infection, ROCK1 activation triggers the ROCK1/LIMK1/CFL1 pathway and NHE1-mediated intracellular alkalinization, promoting cytoskeletal remodelling and facilitating viral entry. Treatment with a ROCK inhibitor or siRNA-mediated ROCK1 knockdown disrupted cytoskeletal rearrangements, reduced NHE1 expression and CFL1 phosphorylation, and impaired viral internalisation. However, during later stages of infection, selective ROCK1 knockdown enhanced MVC replication and viral protein expression. ROCK1 was found to translocate into the nucleus and colocalize with MVC nonstructural proteins NS1 and NP1. Mechanistically, ROCK1 suppression was associated with altered G1/S regulators, including reduced p53/p21/cyclin D1 and increased cyclin E expression, leading to prolonged S-phase progression. Collectively, these findings indicate that ROCK1 exerts stage functions during MVC infection, promoting viral entry while limiting viral replication through regulation of cell-cycle progression. This dual role underscores the complex interplay between viral infection and host signaling pathways and provides mechanistic insights that may inform the development of host-directed antiviral strategies targeting ROCK1 signaling.