Search Results (2,328)

Nanoparticles of the aminopolysaccharide chitosan (ChNPs) are effective delivery platforms for biologically active substances for agrobiotechnological applications and hold great promise for solving precision problems in sustainable and efficient agriculture. This review presents an analysis of research publications during the past 20 years examining methods for producing ChNPs through ionotropic gelation using sodium tripolyphosphate for cross-linking macrochains, which are of practical interest for agriculture. Key aspects of the nanostructure formation process are analyzed, including the influence of the physicochemical characteristics of the aminopolysaccharide, the concentration and ratio of reagents, and ionic cross-linking conditions on the average size, size distribution (polydispersity), and zeta potential of nanoparticles. Particular attention is paid to several approaches proposed in the literature for determining optimal gelation conditions to obtain ChNPs with pre-specified size characteristics. Potential applications of nanostructured preparations based on these nanoparticles for agrobiochemical purposes are considered, including the encapsulation of antifungal, antiviral and antimicrobial agents, pesticides, NPK fertilizers, metal ions, plant extracts, essential oils, etc., to develop biodegradable stimulants for seed germination and plant growth, increased crop yields, and improved agricultural product quality. It is concluded that blocking the protonated amino groups of chitosan with tripolyphosphate anions is undesirable due to the reduced biological activity of the macromolecules and the nanostructured preparations obtained therefrom. An alternative approach for producing ChNPs with high biological activity with neither use of cross-linking agents nor encapsulation of agrochemicals is described. Full article

Objectives: The ongoing evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the current treatment limitations—particularly the emergence of drug resistance and the reduced efficacy of some existing drugs against new variants—highlight the need for novel antiviral strategies with novel action mechanisms. Fusion inhibitors that disrupt six-helix bundle (6-HB) formation during viral entry represent a promising approach. Posaconazole, an antifungal agent, has been identified as a weak fusion inhibitor, but suffers from poor membrane permeability and modest activity. This study aimed to enhance its antiviral potency by conjugating it with cell-penetrating polyarginine peptides and to investigate the mechanism of action. Methods: A series of posaconazole-polyarginine conjugates were synthesized via click chemistry. Antiviral activity was evaluated using pseudotyped SARS-CoV-2 Omicron XDV in HEK293T cells. Mechanisms were investigated by circular dichroism, native PAGE, size-exclusion HPLC, molecular docking, and isothermal titration calorimetry. Metabolic stability was assessed using hepatic microsomes. Results: Posa-R8 exhibited potent antiviral activity comparable to the clinical candidate EK1, with minimal cytotoxicity. Mechanistic studies confirmed that Posa-R8 binds the HR2 region of the spike protein, disrupts 6-HB formation, and inhibits membrane fusion. It also showed strong lipid bilayer affinity and improved phase I metabolic stability over EK1. Conclusions: Polyarginine conjugation enhances the membrane-binding affinity and antiviral efficacy of posaconazole. Posa-R8 represents a promising lead for developing next-generation SARS-CoV-2 fusion inhibitors. Full article

Avian orthoreovirus (ARV) has re-emerged as one of the most important viral pathogens affecting modern poultry production worldwide. In China, the epidemiological landscape of ARV has undergone a substantial transformation over the past decade, characterized by increasing genotypic diversity, frequent genome reassortment, an expanding host range, and recurrent vaccine-breakthrough outbreaks. Growing evidence indicates that contemporary ARV populations evolve within a dynamic multispecies transmission network shaped by intensive poultry production, host adaptation, and vaccine-associated selective pressures. Recent molecular studies have revealed extensive genetic heterogeneity among circulating strains and highlighted the limitations of conventional σC-based classification systems for accurately describing viral evolution, pathogenicity, and antigenic diversity. Whole-genome analyses further demonstrate that reassortment among chicken-origin, duck-origin, and goose-origin orthoreoviruses plays a pivotal role in generating novel viral variants with altered biological properties. In parallel, accumulating evidence suggests that ARV exerts broad immunomodulatory effects through the disruption of innate antiviral signaling, impairment of lymphoid organ function, interference with vaccine responsiveness, and the enhancement of susceptibility to secondary infections. These findings indicate that ARV should be regarded not only as an arthrotropic pathogen but also as an important immunopathological agent influencing flock health and productivity. This review summarizes current knowledge of ARV in China, with an emphasis on molecular epidemiology, genomic evolution, reassortment mechanisms, transmission ecology, immune interference, vaccine escape, and integrated prevention strategies. Particular attention is given to the increasing importance of whole-genome surveillance, phylodynamic analysis, and multispecies epidemiological monitoring for understanding contemporary ARV evolution. Future perspectives involving structural vaccinology, precision immunization, metagenomics-assisted surveillance, and predictive evolutionary modeling are also discussed. Collectively, sustainable ARV control will likely require genome-informed and adaptive prevention frameworks integrating virology, immunology, epidemiology, and precision poultry management. Full article

Background: Hepatitis B and C viral infections remain a significant global health challenge, despite the implementation of an effective direct-acting antiviral (DAAs) and nucleos(t)ide analogues (NAs). Current HBV therapy is not curative as stopping therapy usually leads to active disease in most patients requiring long-term treatment. Although current HCV-DAAs are highly effective they fall short due to arising drug-resistance and have limited ability to avert re-infections. Furthermore, current HCV DAA treatments lead to the reactivation of occult HBV infection, compromising the effectiveness of current antiviral therapies, and increasing the risk of severe liver complications like cirrhosis and hepatocellular carcinoma. In addition, current treatments do not restore the immune dysfunction, a characteristic of chronic HBV infection. Given the global burden of disease, there is an urgent need for more effective therapy that can shorten the duration of treatment and achieve high rates of HBsAg reduction. Combining an antiviral to reduce viral antigen burden and an immunomodulator to boost the immune response could provide an effective treatment for HBV/HCV infections. Methods: In this study, we explored the potential of a novel bacterial therapeutic agent, heat-killed Caulobacter crescentus (HKCC), as an alternative and/or adjunct host-based therapy for HCV and HBV infections. Here, we have investigated the antiviral effects of the HKCC-stimulated human PBMCs using in vitro HCV and HBV infection models to assess viral replication, viral relapse responses, protein expression, and cytotoxicity. Results: Our findings reveal that HKCC induced a multi-functional cytokine response (IFN, TNF, IL-2, IL-10, IL-6, IL-17A, and IL-22) in PBMCs obtained from multiple healthy donors. Supernatants collected from these HKCC-stimulated human PBMCs, alone and in combination with antivirals, strikingly inhibited HCV replication and viral relapse responses without inducing any cytotoxic effects on HCV-1a replicon cells. In addition, these PBMC supernatants, with or without antivirals, led to the suppression of HBV DNA replication and inhibited HBsAg and HBeAg production in HepG 2.2.15 cells. Conclusions: In conclusion, HKCC is a promising candidate for eliminating HBV and HCV infections, and warrants further investigation to potentially contribute to the development of a novel host-based immunotherapy. Full article

For nearly a century, since the discovery of penicillin by Alexander Fleming, we have used covalent inhibitors as antimicrobial drugs. The success of penicillin in treating microbial infections led to numerous other antibiotics containing β-lactam, the reactive warhead that forms the covalent adduct, exemplified by later-generation cephalosporins with approvals into 2020. In parallel, early non-β-lactam covalent agents also emerged, extending covalent mechanisms beyond β-lactam antibacterials to antifungal, antiparasitic, and antiviral applications. Despite the successes of covalent mechanisms of action, there are still considerable safety concerns due to the possibility of off-target covalent adducts which may lead to significant side effects. This review provides an overview of non-β-lactam covalent antimicrobials across all major pathogen classes, organized by their warhead class, covalency, and resistance mechanisms, and outlines design and clinical-level mitigation strategies. We trace the field from the serendipitous discovery of penicillin to the intentional design of new drugs, with a discussion of changes in perception and evolution of technology that enable modern covalent drug design. Full article

Machupo virus (MACV) is the causal agent of Bolivian Hemorrhagic fever. It is highly pathogenic, has a high mortality rate, and currently lacks specific treatments or vaccines. MACV belongs to the Arenaviridae family, which uses a cap-snatching mechanism during the transcription process. Its viral polymerase, the L protein, harbors the endonuclease activity required for cap snatching, making it a suitable target for the development of antiviral therapeutics. We combined experimental and computational methods to characterize MACV endonuclease activity and evaluate inhibitors. A fluorescence resonance energy transfer (FRET) assay was used to measure the enzymatic activity of endonuclease and identify potent inhibitors via high-throughput screening. FRET assays identified BW-148, an inhibitor with a 48.4 µM (95% CI: 37.3–59.3 µM; R² = 0.98) IC₅₀, and a K_D of 13.7 µM (95% CI: 8.2–19.2 µM, n = 3). Docking studies reveal that BW-148 may bind near the MACV endonuclease catalytic site, inhibiting enzymatic activities by metal chelating. BW-148 is a useful lead compound for further optimization of Machupo endonuclease inhibitors. Full article

Extensive efforts have been undertaken by numerous researchers to control respiratory viruses across the domains of diagnosis, prevention, and treatment. In this study, we developed a niclosamide–polysaccharide nasal spray (NPNS) formulation based on xanthan gum (XG), a naturally derived polysaccharide, and niclosamide, a conventional anthelmintic agent. We then evaluated its therapeutic efficacy following intranasal administration under influenza virus-infected conditions. NPNS was assessed for cytotoxicity under Good Laboratory Practice (GLP) conditions in accordance with ISO 10993-5, and no cytotoxic effects were observed. In influenza virus-infected human nasal epithelial cells (HNEc), NPNS treatment resulted in at least 92.5% suppression of viral gene expression. Furthermore, NPNS demonstrated significantly greater antiviral activity compared to Placebo 1 and Placebo 2, which were formulated by excluding niclosamide and XG, respectively. Owing to the physicochemical properties conferred by XG, NPNS exhibited prolonged retention on the nasal mucosa in a mouse model. Consistently, NPNS showed potent antiviral efficacy in influenza-infected mice. In addition, NPNS treatment was associated with the downregulation of S-phase kinase-associated protein 2 (SKP2), a host factor known to facilitate intracellular viral replication. Collectively, these findings suggest that NPNS may serve as a first-line protective barrier during the early stage of influenza infection by simultaneously blocking viral entry and suppressing viral replication through its dual physicochemical and molecular mechanisms. Full article

Background/Objectives: Chronic hepatitis C (CHC) infection is an independent risk factor for developing type 2 diabetes mellitus (T2DM). However, it is unknown if antiviral treatment, especially with direct-acting antivirals (DAAs), changes long-term glycemic outcomes. Methods: We conducted a retrospective comparative cohort study of 2489 patients with chronic hepatitis C (CHC) in southern Taiwan between 2005 and 2022 who underwent treatment with either an interferon (IFN)-based or direct-acting antiviral agent (DAA) regimen. Given the distinct treatment eras of IFN and DAA therapies, potential temporal confounding was considered in the analytical design. Patients with existing diabetes or co-infections were excluded. The incidence of new-onset T2DM and longitudinal HbA1c levels were compared between treatment groups over a mean follow-up period of 2.56 years. Results: DAA-treated patients demonstrated a lower crude cumulative incidence of T2DM compared with IFN-treated patients (2.46% vs. 6.91%). However, adjusted analyses did not demonstrate a statistically significant difference between treatment groups. The cumulative risk appeared to plateau after the third year among DAA recipients. Post-therapy, HbA1c levels remained stable in both groups at between 5.5% and 6.5% over as long as five years. Splitting regression revealed that BMI ≥ 30 kg/m², and not treatment type or achieved SVR, was an independent T2DM risk factor. The lowest rates of diabetes incidence were associated with pan-genotypic DAA regimens. Conclusions: DAA-treated patients showed lower crude T2DM incidence than IFN-treated patients; however, this difference was not consistently significant after adjustment for baseline factors. Viral eradication may be associated with favorable metabolic trends; however, the present findings do not establish a causal protective effect against incident T2DM. While increased BMI remained an independent predictor of post-treatment diabetes risk. Full article

Porcine coronavirus is one of the prevalent enteric coronaviruses in pigs, causing watery diarrhea and even death in suckling piglets and resulting in giant losses to the pig industry. However, effective antiviral strategies against PDCoV remain limited. Notoginsenoside R1 (NG-R1), a saponin extracted from Panax notoginseng, exhibits diverse bioactivities, but its antiviral potential has not been fully characterized. Herein, we systematically investigated the anti-PDCoV effect of NG-R1 and its underlying mechanism. NG-R1 showed no cytotoxic effect on LLC-PK1 cells and exerted antiviral ability against PDCoV infection through targeting the whole life cycle of the virus. In addition, network pharmacology analysis identified calcium signaling as a potentially relevant pathway involved in the antiviral activity of NG-R1. Further data demonstrated that PDCoV infection disrupted intracellular calcium homeostasis, whereas NG-R1 treatment partially restored calcium balance and attenuated endoplasmic reticulum (ER) stress. Moreover, NG-R1 modulated the expression of SERCA2, a key regulator of ER calcium transport. Thapsigargin, an inhibitor of SERCA2, showed similar antiviral capacity to NG-R1. Collectively, our findings suggest that NG-R1 exerts antiviral activity against PDCoV, potentially through regulation of calcium homeostasis mediated by SERCA2. This study provides a theoretical basis for the development of novel antiviral agents targeting calcium signaling pathways. Full article

Herpes simplex virus type 1 (HSV-1) remains a significant pathogen, particularly in immunocompromised patients. The emergence of drug-resistant strains necessitates alternative therapeutic agents. Lentinula edodes (LE), Hypsizygus marmoreus, and Pleurotus eryngii are edible mushrooms with recognized medicinal properties. However, their effects on drug-resistant HSV-1 remain unclear. This study characterized metabolites from high-temperature/high-pressure (121 °C) water extracts of fresh and dried fruiting bodies and evaluated anti-HSV-1 activities using in vitro and in silico approaches. Metabolic profiles were analyzed by electrospray ionization–quadrupole time-of-flight mass spectrometry. Antiviral activity against HSV-1 KOS (wild-type) and HSV-1 dxpiii (drug-resistant) strains was assessed by plaque assays and qPCR. Molecular docking and network pharmacology were performed on candidate compounds. LE extract from dried mushroom tended to show the highest levels of selected major bioactive constituents, along with greater antioxidant activities. All extracts significantly inhibited viral infection and gene expression in both strains. LE extract from dried mushroom modulated the expression of NFKB1 and IL6. Molecular docking analysis revealed that eritanidine showed a predicted binding affinity to HSV-1 DNA polymerase (−7.95 kcal/mol). Additionally, eritanidine, 5′-methylthioadenosine, and 3-indoleacrylic acid were predicted to interact with TNF and MAPK1. Several compounds also demonstrated favorable drug-likeness properties. Overall, these mushroom extracts are promising natural sources of antiviral agents against HSV-1, including drug-resistant variants. Full article

Dengue virus infection is a febrile illness caused by the Orthoflavivirus Dengue, which is transmitted by the mosquitoes Aedes aegypti or Aedes albopictus. Despite the fact that Dengue virus (DENV) is present in tropical and subtropical areas, climate change with global warming has been associated with the spread of Aedes aegypti and Aedes albopictus mosquitoes in several other regions worldwide. Notably, as the presence of Aedes albopictus has been confirmed in Southern Europe, already locally transmitted cases of Dengue virus infection have been reported in Europe. Apart from Europe, Australia has reported DENV cases in the 21st century that have been associated with the transmission of Aedes aegypti in the neighboring islands. Climate change, namely increasing temperatures, higher humidity and rainfalls, together with the development of urban heat islands, uncontrollable deforestation and urbanization, travelling and trade, has contributed significantly to the spread of DENV infection. Modern diagnosis based upon the advent of “multi-omics” techniques and machinery learning programs will be of the utmost importance for the early and accurate diagnosis of DENV infection. Finally, preventive measures for controlling Dengue virus infection, such as the use of repellents, educational programs, and improvement in water storage and waste management at the community levels would be very useful. Regarding climate change, the One Health Approach by integrating collaboration of various sectors and raising public awareness seems to be of the utmost importance in this context. Further investigations regarding the development of antiviral agents and vaccines will be an important asset in our armamentarium against DENV infection. Full article

Marburg virus (MARV), a highly pathogenic member of the Filoviridae family, causes severe hemorrhagic fever with a high case fatality rate and currently lacks effective therapeutics. The viral entry process, mediated by the interaction between the MARV glycoprotein (GP) and host receptor C-type lectin domain family 4 member M (CLEC4M) (L-SIGN), represents a critical target for early-stage intervention. The active compounds from BindingDB and the decoy from DUDE were used. The RDKit was used for feature engineering. Machine learning models were trained on an initial dataset consisting of 56 active chemicals and 1232 decoys. Among the tested algorithms, the Random Forest model demonstrated superior performance, achieving the highest discriminative ability (AUC = 0.93, MCC = 0.88) on the test set. Virtual screening of 11,032 phytochemicals resulted in 120 predicted actives, of which 42 compounds satisfied drug-likeness criteria. Subsequent molecular docking identified three lead compounds (PubChem IDs: 42608095, 5281601, and 11243993) with moderate-to-promising binding affinities (−6.3 to −6.5 kcal/mol) toward the CLEC4M binding site. ADMET analysis revealed favorable pharmacokinetic and toxicity profiles for the selected lead compounds. DFT calculations of the three compounds highlighted their electronic stability and reactive nature, indicating that PubChem IDs 42608095 and 5281601 possess particularly stable electronic properties conducive to favorable target interactions. Combining machine learning models with molecular docking and Molecular Dynamics (MD) simulations worked well in finding promising phytochemical inhibitors. The MM/GBSA binding free energy calculations further confirmed binding affinities, with values of −10.83 and −11.08 kcal/mol, respectively, suggesting favorable complex stability. These findings provide a pathway for developing new antiviral agents against MARV, pending further experimental validation and optimization. Full article

Background: Dental caries is a chronic disease mediated by biofilm, which is caused by Streptococcus mutans, and enamel genetics modulates susceptibility. The variants of ENAM might alter the adhesion of enamel and bacteria. One important anti-viral target is sortase A (SrtA), which restricts colonization but does not have an impact on bacterial survival. Aim: The aim of this study was to find out the relationship between ENAM rs3796704 and dental caries vulnerability among adult Iraqi Arab females and to assess the antibiofilm capacity of eugenol and cinnamic acid against S. mutans SrtA using molecular docking, ADMET prediction, and molecular dynamics modeling. Methods: A case–control study was done on 240 women (aged 25–30 years; 120 caries, 120 controls). HRM real-time PCR was done to genotype ENAM rs3796704. An analysis of allelic and genotypic distributions was done using chi-square tests and odds ratios (p < 0.05). An in silico docking analysis aimed at SrtA (PDB: 4TQX) was performed in AutoDock Vina, and this was followed by ADMET profiling and a 50 ns molecular dynamics simulation (OPLS4/TIP3P, NPT 300 K/1 atm). Results: The level of the G allele was found to be lower in the cases than in the controls (60% vs. 70; OR = 0.6429; p = 0.02), but the level of the A allele was found to be higher in the cases (40% vs. 30; OR = 1.5556; p = 0.02). Docking showed a minor difference in binding affinities with eugenol (−4.961 kcal/mol) and cinnamic acid (−4.939 kcal/mol) as compared with chlorhexidine (−4.692 kcal/mol). Both compounds showed stable binding for more than 50 ns as well as desirable predicted pharmacokinetics. Conclusions: The caries vulnerability in this sample was associated with ENAM rs3796704. Eugenol and cinnamic acid undergo stable dissociative interactions with SrtA and were found to have favorable safety profiles in silico. Therefore, they may be considered as adjunctive anti-virulence agents in the prevention of caries. Full article

Fruits of edible plants belonging to the Rosoideae subfamily are widely consumed as foods or utilized as herbs by various traditional medicine systems. Although these plants are mostly known for their rich phenolic content, there are only limited studies exploiting the relationship between their phenolic composition and bioactivities. The present study constitutes an exploratory chemical and bioactivity screening of fruits harvested from the following eight wildly grown edible Rosoideae plant species: Rosa canina, Rosa sempervirens, Rosa pulverulenta, Rosa arvensis, Fragaria vesca, Rubus sanctus, Rubus idaeus and Sanguisorba officinalis. In this context, the total phenolic and flavonoid contents of the investigated fruits were determined, and the presence of selected individual phenolic compounds was quantified. In addition, their antioxidant properties were evaluated by applying the ABTS and DPPH• assays, and their antiproliferative properties were assessed against selected tumor cell lines. Finally, the antiviral properties of fruits were investigated against fourteen common viruses. Respective results highlighted ellagic acid as the prevailing phenolic molecule for six investigated species, whereas several extracts displayed varying levels of antioxidant activities and moderate antiproliferative effects in the tested models. Furthermore, most extracts exhibited an inhibitory effect against Influenza viruses A (H1N1 and H3N2) and B, displaying IC₅₀ values ranging from 0.6 to 4 μg/mL, comparable to currently used antiviral agents. Finally, the Rubus idaeus and Rosa canina fruit extracts were active against adenovirus-2. Since the bioactivities determined herein are based on single biological replicates, they are considered an indicative lead that provides an initial basis for prioritizing these edible Rosoideae species for future studies, which will involve a more detailed characterization of their bioactive phenolic constituents and more extensive, replicated biological experiments. Full article

Nanobodies are characterized by their small size, high specificity, and strong affinity, making them promising antiviral agents. In this study, a dual-plasmid yeast surface display (YSD) system based on the Saccharomyces cerevisiae a-agglutinin (Aga1p-Aga2p) platform was evaluated for the functional presentation of H5-specific nanobody. To investigate the influence of fusion design on display performance, enhanced green fluorescent protein (EGFP) was fused to Aga2p in two different orientations. Both configurations enabled successful surface display, while the EGFP-AGA2 orientation showed significantly higher display efficiency than AGA2-EGFP (p < 0.001). This optimized configuration was subsequently used to display Nb10, a broadly neutralizing nanobody targeting the hemagglutinin (HA) protein of H5 influenza viruses. Indirect ELISA, immunofluorescence, and confocal microscopy confirmed successful surface localization of Nb10, while flow cytometry revealed 22.10% positive cells compared with 0.30% in the negative control (p < 0.001). In hemagglutination inhibition (HI) assays, the YSD-Nb10 strain exhibited an HI titer of 3log2, whereas no detectable HI activity was observed in the control strain. Collectively, these results demonstrate the feasibility of displaying a functional H5-specific nanobody using a dual-plasmid YSD system and highlight the importance of fusion orientation for efficient surface presentation, providing preliminary practical guidance for optimization of YSD applications. Full article