Microbial pathogenesis最新文献

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.

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.

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.

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.

To investigate the effects of host species and altitude differences on the rumen fungal community (RFC), this study selected Zhongdian yellow cattle and Zhongdian yaks from high-altitude regions (Shangri-La, 3600 m) and Jiangcheng yellow cattle and Jiangcheng water buffalo from low-altitude regions (Jiangcheng, 1100 m) in Yunnan Province as research subjects. The ITS2 high-throughput sequencing (HTS) technology was applied to analyze the composition and diversity of their rumen fungi. The results showed no significant differences in the RFC between different host species within the same altitude environment (P > 0.05), whereas significant differences were observed in the fungal community structure between different altitude groups (P < 0.01). This indicates that under consistent dietary conditions, altitude is the primary factor driving differences in the RFC, while the influence of host species is relatively limited. Our study provides a theoretical basis at the fungal level for understanding the mechanisms of interaction between plateau ruminants and microorganisms.

Objective: This study aimed to investigate the antimicrobial and anti-inflammatory effects of Yinhuapinggan Granules (YHPG) in combination with cefotaxime (CTX) against extended-spectrum beta-lactamase-producing Escherichia fergusonii (ESBL-EF), focusing on how YHPG enhances antibiotic efficacy and modulates inflammatory pathways associated with acute lung injury (ALI).

Methods: The antimicrobial activity of YHPG and CTX was assessed by measuring the minimum inhibitory concentration (MIC) of CTX in the presence of YHPG. qRT-PCR was used to detect the expression of bacterial resistance genes, including acrA, acrB, tolC, OXA-2, TEM-1, and outer membrane porins ompC and ompF. Outer membrane permeability was evaluated using AKP and Bradford assays, while biofilm disruption was analyzed by laser confocal microscopy. In vivo, the effects of YHPG were evaluated in a mouse pneumonia model induced by ESBL-EF infection, including lung index, histopathological changes, and inflammatory cytokine levels. Inflammatory cytokine levels were measured in serum, and the expression of key genes in the NLRP3 inflammasome pathway was analyzed by qRT-PCR.

Results: The combination of YHPG and CTX significantly inhibited the growth of ESBL-EF and enhanced its outer membrane permeability. Additionally, YHPG modulated the expression of key bacterial resistance genes, including acrA, acrB, tolC, OXA-2, and TEM-1, as well as the outer membrane porins ompC and ompF. YHPG also effectively disrupted the biofilm structure of ESBL-EF, reducing its protective barrier. In vivo, YHPG treatment alleviated pulmonary inflammation and tissue damage in mice. Serum levels of pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, were significantly reduced, indicating a potent anti-inflammatory effect. Furthermore, YHPG inhibited the activation of the NLRP3-ASC-CASP1-GSDMD signaling pathway, further mitigating inflammation and tissue damage associated with ESBL-EF infection.

Conclusion: YHPG enhances the antibacterial activity of CTX against ESBL-EF by increasing membrane permeability, disrupting biofilms, and modulating the inflammatory response. This study suggests that YHPG could serve as an adjunctive treatment for antibiotic-resistant infections, offering a promising approach to combat bacterial resistance and inflammation associated with ESBL-EF infections.

Bacterial wilt caused by Ralstonia pseudosolanacearum remains one of the most destructive diseases threatening brinjal production worldwide, as effective management options are limited, resistance in cultivated varieties is often unstable, and chemical control measures are largely ineffective and environmentally unsustainable. In this study, we profiled the rhizobacterial microbiomes of wilt-susceptible Solanum melongena and wilt-resistant S. torvum cultivated in contrasting soils from Cameroon and India representing non-endemic and endemic regions of bacterial wilt. A combined culture-dependent methodology together with 16 S rRNA amplicon sequencing was used to elucidate the structure and functional attributes of the microbial communities. Soil origin was the principal factor influencing microbiome composition (PERMANOVA R² = 0.34, p = 0.001), followed by host genotype (R² = 0.21) and root niche (R² = 0.14). The wilt-resistant S. torvum consistently supported higher bacterial diversity and was enriched with core taxa, including Bacillus and Methanocella. Fourteen rhizobacterial isolates, mainly Bacillus spp., showed strong antagonistic activity against R. pseudosolanacearum. Metabolomic analyses using LC-QTOF-MS/MS and GC-MS indicated the production of lipopeptides and polyketides by Bacillus spp., while Pseudomonas plecoglossicida produced phenazine derivatives and indole-3-acetic acid. In greenhouse experiments, Bacillus cereus, B. velezensis, and Priestia megaterium significantly improved seed germination and seedling vigor at inoculum densities of 10⁶-10⁸ CFU mL^-1. Together, these results show that brinjal-associated rhizobacteria, particularly Bacillus spp. and P. plecoglossicida, contribute to bacterial wilt suppression and offer potential for sustainable disease management.

Staphylococcus aureus is a major human pathogen mainly involved in chronic biofilm-related infections, especially at epithelial surfaces and wound sites, owing to its ability to form antibiotic-resistant biofilms and release virulence factors. Conventional antibiotics often fail to eradicate established biofilms and may contribute to the emergence of drug resistance, underscoring the urgent need for alternative biofilm-inhibiting and antivirulence strategies. Herein, we synthesized several dicyclic peptides, including cyclo(L-Phe, L-Hyp) and its stereoisomers cyclo(L-Phe, D-Hyp) and cyclo(D-Phe, L-Hyp), to evaluate their ability to inhibit S. aureus biofilm formation. All cyclic dipeptides exhibited a minimum inhibitory concentration (MIC) of 1 mg/mL. Biofilm inhibition was assessed via crystal violet staining and confocal laser scanning microscopy. At 0.5 mg/mL (1/2 MIC), the compounds exhibited superior inhibition of 24 h biofilm formation compared with vancomycin, with cyclo(L-Phe, D-Hyp) showing the most profound inhibitory activity. qRT-PCR revealed that at 0.25 mg/mL (1/4 MIC), cyclo(L-Phe, D-Hyp) significantly downregulated the expression of the Agr-quorum-sensing system (RNAIII: -75.7%; hla: -61.7%; psm-α: -73.3%), the ica operon (icaA: -71%; icaD: -76.7%), and sarA (-69.3%) (P < 0.0001). Notably, cyclo(L-Phe, D-Hyp) showed low cytotoxicity (CC₅₀ = 5.13 ± 0.27 mg/mL) and negligible hemolysis (<1 %) at twice its MIC, indicating a favorable safety margin for antimicrobial use. These cyclo dipeptides can be formulated for topical delivery to sites such as skin, mucosa, or open wounds, providing a practical approach for localized treatment of biofilm-associated infections. These findings identify cyclo(L-Phe, D-Hyp) as a promising lead for the development of topical anti-infective agents targeting chronic S. aureus biofilm-associated infections.