Search Results (1,051)

Highly pathogenic avian influenza A virus (HPAIV) H5N1, clade 2.3.4.4b, has emerged as a significant zoonotic threat. H5N1 is widely circulating in wild birds, and an increasing number of spillover events have been observed in a wide range of mammalian species. These cases are primarily reported in countries on the European and American continents. This review describes the likely transmission routes, lesions, and clinical manifestations of HPAIV H5N1 clade 2.3.4.4b in naturally infected mammals, with a focus on the involvement of the central nervous system (CNS). In the analysis, pathological findings were categorized by organ system and host species, which were further divided into terrestrial mammals, marine mammals, and dairy cattle. The most frequently reported clinical manifestations were neurological and respiratory signs in marine mammals and neurological signs and lethargy in terrestrial mammals. Macroscopic and histological lesions were commonly found in the CNS and lungs of terrestrial and marine mammals, while dairy cattle showed mainly gastrointestinal and mammary gland involvement. Immunohistochemistry and reverse transcriptase real-time PCR analyses confirmed high viral loads in brain tissues, indicating a neurological tropism of H5N1 clade 2.3.4.4b. Routes of CNS invasion remain uncertain, though both hematogenous and olfactory nerve pathways are discussed. Recent evidence suggests mammal-to-mammal and vertical transmission, raising concerns for the zoonotic and pandemic potential of this virus. In conclusion, the findings emphasize an urgent need for enhanced surveillance to effectively disclose changes in viral pathogenicity and transmissibility among mammalian hosts. Full article

Human African Trypanosomiasis (HAT; sleeping sickness) and Malaria are life-threatening protozoan infections in tropical regions, with limited treatment options. As part of our ongoing efforts to discover new aminosteroid alkaloids from the Buxaceae family with antiprotozoal activity, which might serve as leads to new drugs against these infections, we investigated the dichloromethane extract from the leaves of Buxus obtusifolia (Mildbr.) Hutch. collected in Kenya, a species native to Kenya and Tanzania. To the best of our knowledge, and based on the most recent comprehensive literature review, this study represents the first phytochemical investigation of this plant. The alkaloid-enriched fraction yielded a total of 24 aminosteroid alkaloids, including 18 hitherto undescribed compounds (2, 3, 5–9, 11, 12, 15–19, and 21–24), along with six known compounds, two of which (1 and 4) are described as constituents of a natural source for the first time. Obtusiaminocyclin (24) represents the first Buxus alkaloid with a novel carbocyclic steroid skeleton with a cyclopropane ring comprising C-9, C-19 and C-11 accompanied by an unprecedented amino bridge between C-3 and C-10. The structures of the isolated compounds were determined using UHPLC/+ESI-QqTOF-MS/MS and NMR spectroscopy. The total crude extract, the alkaloid-enriched fraction, CPC subfractions and all isolated compounds were tested for in vitro antiprotozoal activity against Trypanosoma brucei rhodesiense (Tbr, responsible for East African HAT) and Plasmodium falciparum (Pf, responsible for tropical Malaria) as well as cytotoxicity against mammalian cells (L6 cell line). Deoxycyclovirobuxeine-B (12) (IC₅₀ = 0.8 µmol/L, SI = 108) and 29-trimethoxybenzoyloxy-obtusibuxoline (5) (IC₅₀ = 0.5 µmol/L, SI = 11) showed the highest activities with good selectivity indices against Tbr and Pf, respectively. Consequently, our findings provide valuable aminosteroid candidates that can serve as promising leads in our ongoing search for new drugs against HAT and Malaria. Full article

Influenza A virus (IAV) has a wide range of avian and mammalian hosts, leading to disease outbreaks and increasing the risk of panzootics and pandemics. Subtype H5N1 of clade 2.3.4.4b is causing the current high pathogenicity avian influenza (HPAI) panzootic. Environmental changes are fuelling the spread of HPAI H5N1 in wildlife worldwide, with occasional spillover events from seabirds to cetaceans. Sampling difficulties and limited tests available for diagnosis are a challenge to cetacean virology research. Understanding the risk of HPAI outbreaks in cetaceans requires a comprehensive examination of events of IAV infection. Documented cases relate to IAV subtypes H1N3, H13N2, H13N9, and H5N1 and have been reported in cetaceans sampled in the Pacific, Atlantic, and Arctic Oceans. The number of H5N1 IAV isolated from cetaceans is increasing and affects six host species of the families Delphinidae and Phocoenidae of the suborder Odontoceti. The analysis of 40 molecular markers of viral adaptation to mammals in 21 H5N1 cetacean isolates reveals mutations are present in three viral proteins: hemagglutinin (HA), polymerase basic protein 2 (PB2), and nucleoprotein (NP). Phylogenetic analysis of HA and PB2 sequences isolated from cetaceans and co-occurring cases in seabirds and marine mammals do not support sustained transmission of the virus between cetaceans. IAV H5N1 appears to be reaching cetaceans after spillover from seabirds and other marine mammals. Increasing worldwide surveillance of IAV infection of cetaceans is crucial, as these marine mammals are sentinel species for human pandemic preparedness and key species for marine biodiversity conservation and ecosystem health. Full article

The H3N8 low pathogenic avian influenza virus (LPAIV) exhibits broad host tropism, infecting diverse avian and mammalian species, raising concerns about its zoonotic potential. Following the emergence of human infections with H3N8 LPAIV in China, including a fatal case, we investigated the epidemiological and virological characteristics of this virus in Guangdong Province. In 2022, a serological survey revealed H3N8 seroprevalence rates of 10.85% in farmed chickens and 7.97% in ducks. We isolated three H3N8 viruses, designated as A/chicken/Qingyuan/22/2022 (H3N8); A/chicken/Qingyuan/31/2022 (H3N8); and A/chicken/Qingyuan/15/2022 (H3N8), and found that these chicken isolates, like the human isolate A/Changsha/1000/2022, share the same E190 residue. This residue can synergize with sites such as Q226 and G228 to enhance binding affinity for SAα-2,6-Gal. Additionally, they harbor the three amino acid residues N193, W222, and S227. Among these, N193 has the potential to form hydrogen bonds with α2-6-linked glycans, while W222 and S227 may alter the conformational flexibility of the 220-loop. These two effects collectively endow the H3N8 isolates with dual receptor-binding properties. These findings suggest a shift in receptor specificity, potentially facilitating viral adaptation to mammalian hosts. Characterization of viral genome detection dynamics, and histopathology in animal models further elucidated the viral infection dynamics. Our study provides critical insights into the evolutionary trajectory and zoonotic potential of the H3N8 LPAIV. Full article

Background: Cystic echinococcosis (CE) is a globally distributed zoonosis triggered by the larval stage of Echinococcus granulosus (E. granulosus), impacting humans and an extensive array of mammalian intermediate hosts. EGR-01664 is the major egg antigen of E. granulosus, but almost nothing is currently known about the function of EGR-01664 from E. granulosus. Methods: This study aimed to investigate the E. granulosus EGR-01664 gene (GenBank ID: 36337379), and the recombinant EGR-01664 protein was expressed successfully. Next, the transcription of the EGR-01664 gene across various developmental stages of E. granulosus was analyzed. Its spatial expression patterns in adult worms and protoscoleces were characterized using both quantitative PCR (qPCR) and immunofluorescence assays. Furthermore, the immunomodulatory effects of rEGR-01664 on cell proliferation, nitric oxide production, and cytokine secretion were examined by co-culturing the recombinant protein with canine PBMCs. Results: The rEGR-01664 could be recognized by sera from dogs infected with E. granulosus. Immunofluorescence assay (IFA) localization revealed the protein’s presence in the epidermis of protoscoleces, the adult epidermis, and some parenchymal tissues. qPCR revealed that EGR-01664 mRNA levels were significantly higher in protoscoleces compared to adults (p < 0.0001). At a concentration of 20 μg/mL, rEGR-01664 could significantly activate the transcription and expression of IL-10, TGF-β1, IL-17A, and Bax in canine PBMCs. However, with an increase in concentration, it inhibited the expression of IFN-γ, Bcl-2, GSDMD, IL-18, and IL-1β. These results suggest that the EGR-01664 gene plays a crucial role in the development, parasitism, and reproduction of E. granulosus. In vitro studies have shown that rEGR-01664 protein regulates the immune regulation function of canine PBMCs, suggesting its potential as a vaccine adjuvant or immunotherapy target. Conclusions: EGR-01664 may modulate canine PBMC functions to regulate host immune responses, thereby facilitating our understanding of how E. granulosus EGR-01664 contributes to the mechanism of parasitic immune evasion. Full article

Background/Objectives: In the Brazilian Amazon, which accounts for over 99% of national malaria cases, 34,260 cases were reported as of August 2025, predominantly caused by Plasmodium vivax, responsible for 86.69% of the infections. The increasing resistance of the parasite to conventional therapies highlights the urgent need for novel control strategies, with essential oils and plant-derived substances emerging as promising alternatives. Methods: In this context, we evaluated the anti-Plasmodium potential of Piper alatipetiolatum essential oil and its major constituent 6-ishwarone against P. vivax, including cytotoxicity in Vero and PBMCs, molecular docking on dihydrofolate reductase (DHFR) and lactate dehydrogenase (LDH), and in silico pharmacokinetic profiling. Results: Both the oil and 6-ishwarone inhibited P. vivax dose-dependently (2.1 ± 1 to 100%), with IC₅₀ values of 9.25 µg/mL and 3.93 µg/mL, respectively. Importantly, no cytotoxic effects were observed at 24 h, with cell viability ranging from 94.7% to 98.3%, highlighting the selectivity of these compounds towards the parasite over mammalian cells. Docking studies indicated selective binding of 6-ishwarone to DHFR (−7.7 kcal/mol; Ki = 2.27 µM) with key interactions (Trp816, Lys820, Tyr819, Asn823, Thr865), whereas binding to LDH was weaker (−6.2 kcal/mol; Ki = 28.10 µM), suggesting DHFR as the primary molecular target. In silico ADMET predictions and experimental data indicated favorable drug-like properties: TPSA = 20.23 Ų, moderate lipophilicity (LogP = 3.37), soluble (ESOL Log S = −3.58; Ali Log S = −3.89; Silicos-IT Log S = −2.84), high gastrointestinal absorption, BBB permeability (0.985), not a P-glycoprotein substrate (0.11), and low likelihood of CYP inhibition. Toxicity predictions showed non-mutagenic and non-hepatotoxic effects, low cardiotoxicity (hERG inhibition risk 0.08–0.32), low reproductive toxicity (0.03), moderate neurotoxicity (0.28), low acute toxicity (oral LD₅₀ = 2.061 mol/kg), and low chronic toxicity (LOAEL = 1.995 log mg/kg/day). Conclusions: Together, these findings demonstrate that essential oil and 6-ishwarone of P. alatipetiolatum are selective, bioavailable, and promising natural leads for antimalarial drug development. Full article

Trypanosoma cruzi, the etiological agent of Chagas disease, exhibits remarkable developmental plasticity that enables its survival across distinct environments within the insect vector and mammalian host. This review focuses on two critical differentiation processes—metacyclogenesis and epimastigogenesis—emphasising their environmental triggers, metabolic regulation, and roles in parasite transmission and life cycle progression. Metacyclogenesis, occurring in the hindgut of triatomine vectors, transforms replicative epimastigotes into infective metacyclic trypomastigotes and is tightly controlled by factors such as nutrient starvation, pH, and temperature. In contrast, epimastigogenesis allows trypomastigotes to revert to epimastigote forms, primarily in the vector midgut, as part of the parasite’s adaptation to vector colonisation. We compare these processes through the lens of stress-induced signalling and proteomic reprogramming, highlighting their metabolic divergence and ecological significance. Emerging evidence also suggests that extracellular vesicles (EVs) released by different parasite forms may actively modulate these transitions, supporting parasite communication and immune evasion strategies. A better understanding of these transitions provides novel insight into parasite adaptation and reveals potential molecular targets for disrupting the life cycle of T. cruzi. Full article

Calcineurin (CaN), a Ca²⁺-dependent phosphatase, plays key roles in eukaryotic cell signaling. We investigated whether Leishmania amazonensis’ two infective forms—promastigotes and amastigotes—exhibit differences in CaN expression, localization, and functional impact, using two canonical inhibitors (cyclosporin A, CsA; tracolimus, FK506). At high 40 µM CsA, promastigotes showed reduced viability, whereas amastigotes remained resistant. FK506 had no effect on either form. At a sub-lethal 25 µM CsA, parasite proliferation remained unaffected. In parasite–macrophage co-incubation assays, phosphorylation patterns differed: amastigotes—but not promastigotes—showed increased serine/threonine phosphorylation upon CaN inhibition. Western blotting and in silico data revealed higher CaN catalytic (CaNA2) and regulatory (CaNB) subunit expression in amastigotes than promastigotes. Immunofluorescence localized CaNA prominently in both cytoplasm and nucleus of promastigotes, but predominantly cytoplasmic in amastigotes; CaNB was largely cytoplasmic in both. In silico localization predictions suggested strong membrane associations for CaNA in Leishmania, contrasting with mammalian models. Subcellular fractionation confirmed CaNA enrichment in membrane fractions, with CaNB in cytoplasmic and nuclear fractions. Collectively, these findings reveal form-specific differences in expression, subcellular distribution, and inhibitor responses of CaN in L. amazonensis, highlighting its potential as a stage-specific therapeutic target in leishmaniasis. Full article

Background/Objectives: The rapid emergence of antibiotic-resistant oral pathogens has rendered many conventional therapies increasingly ineffective. Antimicrobial peptides (AMPs) have emerged as a promising therapeutic alternative due to their unique mechanisms of action and low propensity for inducing resistance. The delivery of novel therapeutic AMPs against oral cavity bacterial infections requires effective pharmaceutical dosage formulations. This study investigated the potential of two liposomal formulations for the association and delivery of the antimicrobial peptide (AMP) LL17-32 against the dental bacterial pathogen Porphyromonas gingivalis. Methods: Liposomes composed of either negatively charged soya lecithin (SL) or neutrally charged dioleoyl-phosphatidylcholine (DOPC) phospholipids were formulated and characterized based on their hydrodynamic size distribution, ζ-potential, morphology, membrane fluidity, peptide association efficiency, stability and release of peptide in vitro under physiological conditions. The characterization of their biological activity included efficiency of bacterial killing, bacterial adherence, and mammalian cell cytotoxicity using human gingival keratinocyte (TIGK) cells. Results: Both liposomal formulations exhibited spherical morphology with hydrodynamic diameters smaller than ~170 nm and demonstrated good colloidal stability. LL17-32 showed high association efficiency with both liposomal membranes, with no detectable LL17-32 in vitro release. In biological assays, peptide-loaded DOPC liposomes exhibited dose-dependent bactericidal activity against P. gingivalis, whereas SL liposomes significantly attenuated the bactericidal effect of LL17-32. Both formulations displayed reduced cytotoxicity toward human gingival keratinocyte (TIGK) cells versus free peptide. Conclusions: These findings suggest that DOPC liposomes represent a promising delivery system for LL17-32 by adhering to P. gingivalis and exhibiting minimal cytotoxicity to mammalian cells. This study emphasises the critical role of lipid charge in designing AMP delivery systems for antibacterial applications, while it additionally demonstrates the utility of flow cytometry as a quantitative tool to assess liposome–bacteria association. Full article

Helminth parasites infect mammalian hosts through complex life cycles, mostly triggering T helper type 2 (Th2) immune responses characterized by interleukin-4 (IL4), interleukin-5 (IL5), and interleukin-13 (IL13) production. Environmental chemical exposures may modulate these immune pathways, potentially affecting infection outcomes. Using The Comparative Toxicogenomics Database (CTD), we analyzed chemical–gene interactions affecting IL4, IL5, and IL13 genes to identify chemicals capable of modulating Th2 immunity and their associated expression profiles. Accordingly, a total of 818 chemicals can interact with IL4, IL5 and/or IL13, with 145 chemicals showing the potential of affecting all three genes. These 145 chemicals include air pollutants (8.3%), allergens (2.7%), bioactive molecules (8.3%), industry-related chemicals (14.5%), medicinal drugs (21.4%), metal and metal-containing chemicals (8.3%), pesticides (3.4%), plant compounds (12.4%), and others (20.7%). We observed a greater number of chemicals associated with increased (n = 95) gene expression compared to decreased (n = 14) gene expression, suggesting a Th2 pathway hyperactivation caused by chemicals capable of affecting IL4, IL5 and IL13. Eight classes of parasitic diseases were observed among chemical-associated conditions. Environmental chemicals extensively modulate Th2 immune responses through diverse molecular mechanisms. The trend concerning upregulation of Th2 pathways may enhance antiparasitic protection but, on the other hand, could predispose individuals to allergic diseases, among other Th2-related conditions. These exploratory findings suggest that chemical pollution may influence the susceptibility and pathogenesis of helminth infections and highlight the need for the incorporation of exposome-based approaches in parasitology research. Full article

Archaea, one of the three domains of life, are increasingly recognized as consistent, though often underappreciated, members of the human microbiome, yet their roles in health and disease remain poorly understood. Unlike bacteria, no archaeal species have been conclusively identified as primary mammalian pathogens, but their widespread presence across diverse body sites suggests potential indirect contributions to host physiology and pathology. Current evidence is synthesized on archaeal diversity and habitat specificity across multiple human-associated sites, encompassing the gastrointestinal, aerodigestive, and urogenital tracts as well as the skin. Methanogens dominate the lower gastrointestinal tract (LGT), where they influence fermentation dynamics and methane production, while members of the class Nitrososphaeria are prevalent on the skin and upper aerodigestive tract (UAT), reflecting ecological specialization. Variability in archaeal composition across niches highlights possible links to disease processes: methanogens have been associated with irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), obesity, and colorectal cancer (CRC); Methanobrevibacter oralis is enriched in periodontal disease; and archaea have been detected in the lungs of cystic fibrosis patients. Although archaea lack canonical bacterial virulence factors, they may contribute indirectly through metabolic cross-feeding, immune modulation, synergy in polymicrobial infections, and alteration of host–microbiome network dynamics. This review explores the emerging concept of the human “archaeome”, evaluates current evidence for archaeal involvement in disease, and highlights emerging technologies, such as bacteria-MERFISH and multi-omics profiling, that enable translational applications including microbiome diagnostics, therapeutic targeting, and microbiome engineering. Full article

Background: Mammalian orthoreovirus is a ubiquitous double-stranded RNA virus that causes mild respiratory and enteric infections, primarily in infants and young children. Its significant environmental stability and association with conditions like celiac disease highlight an unmet medical need, as no licensed vaccine or antiviral treatment currently exist. Methods: An immunoinformatics-driven approach was employed to design a multi-epitope vaccine. The highly antigenic inner capsid protein Sigma-2 was used to predict cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and linear B cell epitopes using NetCTL, NetMHCpan, NetMHCIIpan, and IEDB tools. Selected epitopes were fused with appropriate linkers. The construct’s antigenicity, allergenicity, and physicochemical properties were evaluated. The tertiary structure was predicted with AlphaFold2, refined, and validated. Molecular docking with TLR2 and TLR4 was performed using HDOCK, and immune response simulation was conducted with C-ImmSim. Finally, the sequence was codon-optimized for E. coli expression using JCat. Results: The final vaccine construct comprises one CTL, four HTLs, and one B cell epitope. It is antigenic (VaxiJen score: 0.5026), non-allergenic, and non-toxic and possesses favorable physicochemical properties, including stability (instability index: 32.28). Molecular docking revealed exceptionally strong binding to key immune receptors, particularly TLR2 (docking score: −324.37 kcal/mol). Immune simulations predicted robust antibody production (elevated IgM, IgG1, and IgG2) and lasting memory cell formation. Codon optimization yielded an ideal CAI value of 0.952 and a GC content of 57.15%, confirming high potential for recombinant expression. Conclusions: This study presents a novel multi-epitope vaccine candidate against reovirus, designed to elicit broad cellular and humoral immunity. Comprehensive in silico analyses confirm its structural stability, potent interaction with innate immune receptors, and high potential for expression. These findings provide a strong rationale for further wet-lab studies to validate its efficacy and advance it as a promising prophylactic candidate. Full article

African swine fever (ASF), caused by the African swine fever virus (ASFV), is an acute, febrile, highly contagious, and lethal disease that poses a severe threat to the global pig farming industry. Currently, no globally recognized, safe, and effective commercial ASF vaccine has been developed, making vaccination a crucial strategy for outbreak control. The ASFV structural proteins p72, p30, and p54 are key targets for vaccine development. In this study, we developed a novel baculovirus vector-based system for surface display of a recombinant protein comprising epitopes from p72, p30, and p54. Upon infection, the recombinant protein was expressed and anchored on the plasma membrane of Sf-9 cells. Purified virus analysis revealed that the Bac-recombinant protein enhanced gene delivery and transgene expression in mammalian cells compared to the Bac-Wild Type (Bac-WT). In a murine model, the Bac-recombinant protein induced significantly higher IFN-γ and IL-4 levels than Bac-p30 and the negative control. However, further evaluation in swine models is required to confirm its protective potential against ASFV. Furthermore, it also elicited a robust antibody response, generating high-titer Bac-recombinant protein-specific antibodies. Therefore, these findings suggest that the ASFV Bac-recombinant protein is a promising candidate for a vector-based vaccine. Full article

Streptococcus suis (S. suis) is an important zoonotic pathogen that causes severe disease in both humans and pigs, leading to substantial economic losses in the swine industry. Extracellular vesicles (EVs), as critical mediators of host–pathogen interactions, play key roles in bacterial virulence and disease progression. This study aimed to investigate the biological properties of S. suis EVs and elucidate their role in the bacterium’s pathogenesis. We isolated and characterized S. suis EVs, which were found to contain diverse protein molecules. EVs were efficiently internalized by mammalian cells, and concentrations below 50 μg/mL did not affect cell viability. Following uptake, EVs suppressed the production of key pro-inflammatory cytokines (TNF-α, IL-1β, and IL-8) by modulating macrophage metabolism. They also downregulated the expression of major histocompatibility complex class II (MHC-II) and adhesion molecules (VCAM-1 and ICAM-1) during subsequent infections, potentially impairing macrophage-mediated clearance. In addition, EVs served as vectors for efficient cargo delivery and facilitated S. suis adhesion to and invasion of endothelial cells. In infection models, EVs markedly enhanced lethality in Galleria mellonella larvae and promoted tissue colonization in murine models. These findings suggest that S. suis EVs are key mediators of host–pathogen interactions, contributing to colonization and disease pathogenesis. Moreover, they offer novel insights and potential strategies for the prevention and control of S. suis infections. Full article

Background: Borrelia burgdorferi, the causative agent of Lyme disease, releases outer membrane vesicles (OMVs) that may contribute to infection and modulate the host immune response. Although interest in OMVs is growing, few studies have systematically compared methods for isolating OMVs from B. burgdorferi. Methods: In this study, we evaluated two OMV isolation techniques—standard ultracentrifugation and an ion-exchange chromatography-based ExoBacteria™ kit—and examined how serum supplements (rabbit serum vs. exosome-depleted fetal bovine serum, ED-FBS) influence Bb-OMV yield and composition. Gene expression profiles were assessed using RT-PCR, and specific protein content was identified by Western blot analyses. To assess the ability of Bb-OMVs to interact with host cells, Bb-OMVs were co-cultured with MDA-MB-231 triple-negative breast cancer cells. Results: Transmission electron microscopy confirmed that both methods produced spherical Bb-OMVs with intact membrane bilayers. Ultracentrifugation generated larger vesicles (15–180 nm), while the ExoBacteria™ kit yielded smaller vesicles (<50 nm) with a higher double-stranded DNA (dsDNA) content, and protein levels were similar across samples. Cultures grown with rabbit serum produced more Bb-OMVs and had cleaner backgrounds in the TEM images than those grown with ED-FBS. All Bb-OMV samples lacked intracellular markers (DnaK and 16S rRNA) and consistently expressed the outer surface protein OspA, confirming high purity. All isolated Bb-OMVs were taken up by the cells, as indicated by OspA expression, without detectable 16S rRNA, confirming vesicle internalization without bacterial contamination. Conclusions: These findings indicate that isolated OMVs are biologically active and capable of interacting with mammalian cells, highlighting their potential role in host–pathogen interactions and the broader relevance of OMVs in studying bacterial modulation of mammalian cell behavior. Overall, both isolation methods produced high-quality OMVs, with ultracentrifugation yielding slightly more pure vesicles, emphasizing the importance of selecting appropriate isolation methods and culture conditions for functional OMV studies. Full article