Search Results (201)

Avian influenza (AI) significantly threatens poultry health and causes major economic losses in the poultry industry. Vaccination remains crucial for AI prevention and control. The major protective epitopes of influenza viruses are located on hemagglutinin (HA), a surface glycoprotein essential for viral infection. Most influenza vaccines induce neutralizing antibodies against HA to block viral entry. HA maturation requires the HA0 precursor to be proteolytically cleaved at a conserved site by host proteases to yield HA1 and HA2 subunits. A subsequent acidic condition triggers HA conformational changes, enabling viral–host membrane fusion. However, whether HA conformational variations affect immunogenicity remains unclear. In this study, the cleavage site of the HA gene from an H9N2 avian influenza virus was modified to block the proteolytic cleavage of the HA protein. Our results revealed distinct proteolytic patterns of certain mutants, which exhibited either increased or decreased cleavage efficiencies compared to the wild-type (WT) HA. However, none of the mutants exhibited completely abolished HA0 cleavage. To assess the immunogenicity of these variants, BALB/c mice were immunized with DNA vaccines expressing either WT or mutant HA proteins. Strikingly, the mutant HA protein with a 19-amino-acid deletion Dlt5 (P6~P1, P1’~P′13) at the cleavage site exhibited reduced cleavage efficiency and induced significantly higher HI antibody titers compared to the WT. These results offer valuable perspectives for enhancing avian influenza vaccine efficacy through strategic modification of HA cleavage properties. Full article

Snakebite envenoming remains a critical public health issue, and the molecular variability of venoms limits the cross-species efficacy of conventional antivenoms. Here, we conducted a comparative proteomic analysis of Bitis arietans venom to identify conserved peptide regions derived from enzymatic toxins and evaluate their potential relevance for complementary immunotherapeutic applications. Enzyme-enriched venom fractions were isolated through sequential affinity and ion-exchange chromatography and were subsequently characterized using fluorogenic FRET substrates and inhibitor assays. LC–MS/MS analysis identified 1099 proteins and revealed 36 conserved peptides within snake venom metalloproteinases (SVMPs), serine proteases (SVSPs), and phospholipase A₂ (PLA₂), particularly located near catalytic residues and structurally essential motifs such as the HExxHxxGxxH zinc-binding site in SVMPs, the His-Asp-Ser catalytic triad in SVSPs, and the Ca²⁺-binding loop in PLA₂, across Viperidae venoms. These conserved regions were also observed in homologous toxin isoforms from additional Viperidae genera, supporting the evolutionary conservation of key functional domains. While sequence conservation alone does not guarantee neutralization capacity, the identified regions represent strong candidates for structural epitope mapping and targeted antibody development. This study provides a peptide-level framework for advancing complementary antibody-based therapies designed to broaden cross-species toxin recognition, reduce antivenom dosage requirements, and improve clinical outcomes in snakebite envenoming. Full article

The saw-scaled viper Echis carinatus, one of the “Big Four” causes of snakebites in India, is found from Sri Lanka to eastern Iraq. To investigate clinical reports regarding the limited efficacy of Indian polyvalent antivenom (IPAV) against envenomation in Echis carinatus sochureki (ECS) in northwestern India, we obtained 22 snakes from three locations in Rajasthan and identified 148–174 toxin isoforms belonging to 21–25 toxin families in their venom using a bottom-up proteomics approach. All samples showed a high abundance of snake venom metalloproteinases (SVMPs), particularly SVMP class III. Other major components were phospholipases A₂, L-amino-acid oxidases, snake venom serine proteases and snaclecs (C-type lectins). Variation in venom composition among locations in Rajasthan, compared to E. c. carinatus (ECC) from southern India, was primarily due to differences in the relative abundance of these toxin families. Recognition of all venom components by IPAV was poor at lower antivenom concentrations. Notably, SVMP classes II and III were poorly recognized at all venom-to-antivenom ratios in all ECS venoms, and a plasma clotting assay revealed poor neutralization of procoagulant activity. This collaborative study highlights the need for the development of regional antivenoms to effectively treat snakebites in northwestern India. Full article

Prostate cancer (PCa) metastasis is reliant on the activity of proteases, such as matrix metalloproteinase-2 (MMP-2). While increased extracellular heat shock protein 90α (eHSP90α) has been linked to increased MMP-2 activity, this has not been examined in the context of cellular stress. We examined stress-induced eHSP90α in human prostate cell lines by immunoblot. Fluorometric gelatin dequenching and zymography assays measured MMP activity. Wound healing and Matrigel drop invasion assays were used to quantify cell motility. HSP90α knockout (KO) cells were established with CRISPR/Cas9. Proteases were profiled with molecular inhibitors and protein arrays and validated by siRNA knockdown, immunoblot, and motility assays. Stress increased eHSP90 in four out of four human prostate cell lines examined. Surprisingly, it concurrently decreased MMP-2 activity. The functional relevance of this was demonstrated when conditioned media from stressed cells decreased the motility of non-stressed cells. Screening for protease inhibitors that would rescue stress-induced decreases in MMP-2 activity identified a single serine protease inhibitor: aprotinin. Yet rescue with aprotinin was lost in HSP90α KO cells. A protease array identified stress-induced increases in kallikrein-related peptidase 6 (KLK6). Knockdown of KLK6 rescued stress-induced MMP-2 activity and cell motility. In conclusion, we identify a novel stress-induced extracellular network that regulates MMP-2 activity and cell motility. We identified KLK6 as a stress-induced extracellular protease leading to decreased MMP-2 activity and cellular invasion, while eHSP90α is required for the rescue of MMP-2 activity once KLK6 is neutralized. Full article

To address the soil degradation and growth inhibition caused by long-term monoculture of the medicinal plant Chrysanthemum morifolium Ramat. (Hangju), we conducted a controlled experiment comparing a monoculture (control) with seven different intercropping combinations. The intercropping treatments consisted of the main crop paired with pepper, schizonepeta, edible amaranth, dandelion, maize, soya, and purple perilla. Comprehensive assessments were conducted, encompassing plant growth parameters and rhizospheric soil properties. The soil properties included physicochemical characteristics, enzyme activities, and phenolic acid content (4-hydroxybenzoic acid, vanillic acid, and ferulic acid). The results indicated that intercropping significantly altered the rhizosphere environment of Hangju (p < 0.05). Purple perilla and maize emerged as particularly effective companion plants. Intercropping with purple perilla enhanced the aboveground biomass accumulation of Hangju and increased the activities of rhizosphere catalase, sucrase, β-glucosidase, and neutral phosphatase, although it also elevated the contents of three autotoxic phenolic acids. In contrast, intercropping with maize improved Hangju biomass and enhanced the activities of sucrase, urease, neutral phosphatase, and protease, while concurrently reducing the concentrations of all three phenolic acids. Overall, maize demonstrated optimal performance in comprehensively improving soil health by modulating enzyme activities, whereas purple perilla showed a distinct advantage in directly promoting plant growth. Full article

Extraintestinal pathogenic Escherichia coli (ExPEC) is a major cause of infections of the urinary tract, the bloodstream, and other non-intestinal sites in humans. ExPEC often resists the bactericidal action of human immune defenses including complement, antimicrobial peptides, antibodies, and cell-mediated killing. This review provides an overview of the main host defense strategies, and the mechanisms and molecules ExPEC engages to resist these human immune responses. Surface-exposed polysaccharides, outer membrane proteins, cytotoxins, and proteases are all part of the bacterial arsenal of defenses that can neutralize many of the host’s immune defenses. These factors work in concert to enable ExPEC to survive and thrive in extraintestinal environments of the human body. Full article

Sea cucumber peptides have been shown to possess a number of functions, including antioxidant, anti-inflammatory, anti-tumor, and anti-fatigue effects, as well as immune regulation and promotion of collagen synthesis. Among these, high F-value oligopeptides are a promising natural active ingredient demonstrating excellent anti-fatigue effects. This study utilized fresh sea cucumbers as the primary raw material, employing membrane separation technology to investigate the simultaneous separation of sea cucumber polysaccharides and peptides. The process for removing aromatic amino acids during the preparation of high F-value oligopeptides from sea cucumbers was optimized, and the mechanism underlying their anti-fatigue effects was explored. A two-step enzymatic hydrolysis method using neutral protease and composite flavor protease was employed, followed by membrane separation using a 10,000 Da molecular weight ultrafiltration membrane, yielding a sea cucumber peptide yield of 45.00 ± 0.12% and a sea cucumber polysaccharide yield of 51.28 ± 0.63%. Following the removal of aromatic amino acids by means of activated carbon adsorption, the F-value of the high-F-value oligopeptides attained 23.82, with a yield of 24.56%. The experimental findings demonstrated that high-F-value oligopeptides exhibited a substantial increase in the swimming duration of mice and a notable enhancement in their grip strength. These observations signified their substantial anti-fatigue potential. Furthermore, studies have indicated that sea cucumber high-F-value oligopeptides reduce metabolites produced by exercise, enhance muscle protection, increase the activity of antioxidant enzymes in the body, and alleviate fatigue, thereby achieving an anti-fatigue effect. Full article

The ongoing COVID-19 pandemic, caused by SARS-CoV-2, continues to pose major global health challenges despite extensive vaccination efforts. Variant escape, waning immunity, and reduced vaccine efficacy in immunocompromised populations underscore the urgent need for complementary antiviral therapeutics. Here, we report the design, synthesis, and biological evaluation of precision-engineered dermatan sulfate (DS)-mimetic glycopolymers as multi-targeted inhibitors of SARS-CoV-2. Guided by molecular docking and virtual screening, sulfation at the C2 and C4 positions of iduronic acid was identified as critical for binding to the viral spike protein and inhibiting host and viral enzymes, including heparanase (HPSE) and main protease (M^pro). Chemically synthesized DS disaccharides were covalently grafted onto polymer scaffolds via a post-modification strategy, yielding glycopolymers with well-defined assembly that form uniform nanoparticles under physiological conditions. Surface plasmon resonance and pseudovirus assays revealed strong binding to the viral spike protein (K_D ≈ 177 nM), potent viral neutralization, and minimal cytotoxicity. Cellular uptake studies further demonstrated efficient internalization of nanoparticles and intracellular inhibition of HPSE and M^pro. These results establish a modular, non-anticoagulant, and glycosaminoglycan-mimetic platform for the development of broad-spectrum antiviral agents to complement vaccination and enhance preparedness against emerging coronavirus variants. Full article

Long-term fertilization profoundly influences soil biochemical processes and microbial functionality, yet the coupling mechanisms between soil enzyme activities and functional genes in nutrient cycling remain unclear. This study investigated the effects of different fertilization regimes—nitrogen alone (N), nitrogen–phosphorus–potassium fertilizer (NPK), organic fertilizer (M), and combined organic–inorganic fertilizer (MNPK)—on soil properties, enzyme activities, N- and P-cycling-related functional gene abundances, and faba bean (Vicia faba L.) yield in a 45-year ongoing field experiment in subtropical eastern China. Results showed that long-term fertilization significantly affected soil pH, electrical conductivity, nutrient contents, and crop yield. Organic fertilizer addition (M and MNPK) markedly improved soil organic matter, total and available nutrients, and enhanced faba bean grain yield by 75.07–92.79% compared with NPK, whereas NPK had limited benefits on total and available soil nutrients compared with N-only application. Soil enzyme activity analysis revealed that the MNPK treatment achieved the highest urease and neutral protease activities, while acid and alkaline protease activities responded inconsistently. Phosphorus-related enzymes (acid, neutral, and alkaline phosphatases) were strongly stimulated by organic inputs, reflecting enhanced P mineralization potential. Functional gene analysis showed that N-fixation and assimilatory nitrate reduction genes increased under M and MNPK, while N assimilation, N mineralization, anammox, nitrification, denitrification, and dissimilatory nitrate reduction genes were enriched under N treatment. Phosphate uptake and transport genes were upregulated under NPK, M, and MNPK, whereas inorganic P solubilization genes were highest under N. Significant positive correlations were observed among soil enzyme activities, nutrient contents, and faba bean yield, whereas acid and alkaline protease activities showed opposite trends. The relative abundances of N- and P-cycling functional genes exhibited distinct yet coordinated relationships with soil fertility indicators and enzyme activities. These findings provide mechanistic insights into the long-term regulation of soil–microbe interactions and nutrient cycling, offering a scientific basis for sustainable fertilization strategies in agroecosystems. Full article

The composition of the lipophilic components of Centaurea scabiosa L. has been studied. The raw material was subjected to extraction with hexane and methyl tert-butyl ether (MTBE) using both exhaustive and sequential schemes for a detailed characterization. The resulting extracts were fractionated into acidic and neutral components via treatment with alkali solutions. The acidic compounds were converted into methyl esters for subsequent gas chromatography–mass spectrometry (GC-MS) analysis, while the neutral unsaponifiable fractions were separated into groups of different polarities using column chromatography on silica gel. This approach enabled the identification of a complex profile of lipophilic substances. In the acidic fractions, aliphatic acids with chain lengths from C₁₀ to C₃₂, including unsaturated variants, were characterized. The neutral fractions revealed over compounds, encompassing n-alkanes, substantial levels of the unsaturated branched hydrocarbon squalene, and a diverse array of oxygenated terpenoids. The latter were mainly represented by highly active triterpene alcohols and ketones belonging to the ursane, oleanane, lupane, and cycloartane types. The sterol composition was dominated by β-sitosterol and accompanied by cholesterol, campesterol, stigmasterol, stigmast-7-en-3-β-ol, fucosterol, and stigmastan-3-β-ol. Bioactivity screening demonstrated that several of the obtained lipophilic extracts, particularly those of lower polarity, exhibited high inhibitory activity against the main protease of SARS-CoV-2, underscoring the potential of C. scabiosa as a valuable source of anti-coronavirus agents. Full article

Protein fibrils are highly ordered structures. Mung bean protein (MBP) fibrils were fabricated after heating under acidic condition. The formation mechanism, structural variety and antioxidant capacities of mung bean protein fibrils were investigated under different pH conditions. The fibrillation process was characterized by extensive hydrolysis of MBP into low-molecular-weight peptides, which subsequently self-assembled into fibrils with increasing contour length over time. The formed fibrils exhibited a dominant β-sheet structure but demonstrated high sensitivity to pH changes. Upon adjustment to pH 7.0, the fibrils changed into amorphous aggregates, accompanied by a structural transition to random coils. Pretreatment of MBP with neutral protease and chymotrypsin yielded hydrolysates with distinct peptide profiles, leading to the formation of fibrils with varied morphologies upon acidic heating. Furthermore, the antioxidant activity of MBP and its fibrillar aggregates was highly dependent on pH and structural state. While fibril formation at pH 2.0 led to a reduction in radical scavenging activity of MBP, the subsequent pH-shifted aggregates at pH 7.0 resulted in a significant enhancement of antioxidant capacity. These findings provide fundamental insights into the formation, stability, and bioactive properties of MBP fibrils, emphasizing their pH-dependent behavior. Full article

Objectives: This experiment investigated the response of carcass composition, digestive function, hepatic lipid metabolism, intestinal microbiota, and serum metabolomics to excessive or restrictive dietary energy in Ningxiang pigs. Methods: A total of 36 Ningxiang pigs (210 ± 2 d, 43.26 ± 3.21 kg) were randomly assigned to three treatments (6 pens of 2 piglets each) and fed a control diet (CON, digestive energy (DE) 13.02 MJ/kg,), excessive energy diet (EE, 15.22 MJ/kg), and restrictive energy diet (RE, DE 10.84 MJ/kg), respectively. Results: Results showed that EE significantly increased the apparent digestibility of crude protein and total energy (p < 0.01), as well as the activities of jejunum neutral protease and ileal lipase (p < 0.05). With the increase in energy level, the apparent digestibility of ash, dry matter, and ether extract significantly increased (p < 0.01). RE significantly increased high-density lipoprotein cholesterol (HDL-C) content, significantly decreased triglycerides (TG), free fatty acid (NEFA), and total cholesterol (TC) contents, and up-regulated lipoprotein lipase (LPL) mRNA expression in the liver (p < 0.05). EE significantly increased the hepatosomatic index, the contents of low-density lipoprotein cholesterol (LDL-C) and total bile acids (TBA), and significantly up-regulated the mRNA expression of lipogenic genes acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and sterol regulatory element-binding protein-1C (SREBP-1C) in the liver (p < 0.05). The abundance of p_Firmicutes was significantly increased and the abundance of p_Bacteroidetes was significantly decreased in test groups, while the ratio of the two was significantly increased in the RE group (p < 0.05). EE also significantly increased the abundance of g_Clostridium_sensu_stricto_1 (p < 0.05). The identical serum differential metabolites between the EE and RE group belong to phosphatidylcholine (PC), mostly being up-regulated in the EE group and down-regulated in the RE group (p < 0.05), one of which was mapped to the pathway of glycerophospholipid metabolism (KEGG ID: C00157). The relative content of serum trimethylamine N-oxide (TMAO, a microbial metabolite) was significantly decreased in the EE group (p < 0.05). Conclusions: The findings suggest RE had no obvious negative effect on carcass traits of Ningxiang pigs. Apart from exacerbated body fat deposition, EE promoted fat accumulation in the liver by up-regulating the expression of lipogenic genes. Dietary energy changes affect hepatic bile acid metabolism, which may be mediated through the glycerophospholipid metabolism pathway, as well as disturbances in the gut microbiota. Full article

Chronic inflammation constitutes a significant characteristic of sustained infections caused by viral and fungal pathogens, with a strong correlation to the development of cancer, autoimmune disorders, and tissue fibrosis. Viral proteins such as HIV-1 Tat, HBV X (HBx), HPV E6/E7, and EBV LMP1 modulate the host’s immune signaling pathways, primarily through the activation of the NF-κB signaling cascade and the disruption of cytokine equilibrium. These molecular interactions result in a pro-inflammatory microenvironment that facilitates viral persistence, immune evasion, and the process of oncogenesis. Structural investigations have elucidated the mechanisms by which these viral proteins interact with host signaling complexes, thereby highlighting their potential as viable therapeutic targets. Similarly, fungal proteins, including secreted aspartyl proteases (Saps), ribotoxin Asp f1, and chitin-binding proteins, incite chronic inflammation by activating pattern recognition receptors and triggering inflammasome activation. Despite the limited structural information of these fungal proteins, emerging models and bioinformatic analyses identified conserved motifs that are crucial for host interactions. Biologic therapies, encompassing antiviral and antifungal peptides as well as monoclonal antibodies, are currently under development to disrupt these protein-host interactions and modulate inflammatory responses. This review provides structural and functional insight into viral and fungal inflammatory proteins and evaluates the potential of biologics as targeted therapeutic interventions for chronic inflammation associated with infections. We discuss the ongoing clinical trials involving neutralizing antibodies targeting HIV, peptide vaccines aimed at HPV and other promising molecules. Finally, we discuss the current limitations of biologics and possible solutions to translate these promising therapeutics into clinical practice. Full article

Roughly 25% of abalone viscera generated during processing is currently discarded, resulting in substantial protein wastage and environmental contamination. In the present study, abalone viscera served as the raw material; four commercial proteases—papain, bromelain, neutral protease and trypsin—were comparatively evaluated. Among them, the neutral-protease hydrolysate of abalone viscera (AVZH) exhibited the strongest suppression of nitric oxide (NO) release from lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis ultimately led to the identification of 18 novel peptides. Integrating bioinformatic prediction with solid-phase synthesis, two sequences—GYSFTTTAER and IKKPPQDEWGTGL—were further screened and confirmed to possess excellent cytocompatibility and pronounced anti-inflammatory potency. Mechanistic investigations revealed that both peptides dose-dependently attenuated the secretion and mRNA expression of IL-1β, IL-6 and TNF-α and concurrently blocked mitogen-activated protein kinase (MAPK) signaling by down-regulating the phosphorylation of ERK, JNK and p38. These findings demonstrate that abalone viscera represent an abundant reservoir of anti-inflammatory peptides, offering both a theoretical framework and a technological roadmap for the valorisation of marine waste proteins and the development of next-generation natural anti-inflammatory agents. Full article

Osteoarthritis (OA) lacks disease-modifying therapies, in part because key features of the joint microenvironment remain underappreciated. One such feature is localized acidosis, characterized by sustained reductions in extracellular pH within the cartilage, meniscus, and the osteochondral interface despite near-neutral bulk synovial fluid. We synthesize current evidence on the origins, sensing, and consequences of joint acidosis in OA. Metabolic drivers include hypoxia-biased glycolysis in avascular cartilage, cytokine-driven reprogramming in the synovium, and limits in proton/lactate extrusion (e.g., monocarboxylate transporters (MCTs)), with additional contributions from fixed-charge matrix chemistry and osteoclast-mediated acidification at the osteochondral junction. Acidic niches shift proteolysis toward cathepsins, suppress anabolic control, and trigger chondrocyte stress responses (calcium overload, autophagy, senescence, apoptosis). In the nociceptive axis, protons engage ASIC3 and sensitize TRPV1, linking acidity to pain. Joint cells detect pH through two complementary sensor classes: proton-sensing GPCRs (GPR4, GPR65/TDAG8, GPR68/OGR1, GPR132/G2A), which couple to G_s, G_q/11, and G_12/13 pathways converging on MAPK, NF-κB, CREB, and RhoA/ROCK; and proton-gated ion channels (ASIC1a/3, TRPV1), which convert acidity into electrical and Ca²⁺ signals. Therapeutic implications include inhibition of acid-enabled proteases (e.g., cathepsin K), pharmacologic modulation of pH-sensing receptors (with emerging interest in GPR68 and GPR4), ASIC/TRPV1-targeted analgesia, metabolic control of lactate generation, and pH-responsive intra-articular delivery systems. We outline research priorities for pH-aware clinical phenotyping and imaging, cell-type-resolved signaling maps, and targeted interventions in ‘acidotic OA’ endotypes. Framing acidosis as an actionable component of OA pathogenesis provides a coherent basis for mechanism-anchored, locality-specific disease modification. Full article