Search Results (811)

Seasonal human coronaviruses (HCoVs) continue to undergo adaptive evolution under structural and immune-mediated constraints. We investigated the molecular epidemiology and spike (S) protein structural variation of circulating coronaviruses in Riyadh, Saudi Arabia, during the 2025–2026 winter season, with particular emphasis on genotype persistence and glycosylation architecture in HCoV-OC43. Among 293 nasopharyngeal aspirates (NPAs) collected from hospitalized patients with acute respiratory illness, HCoV-OC43 was detected in 26 cases (8.87%), whereas other seasonal coronaviruses were not identified. Partial sequencing of the S gene revealed 97.84–98.23% nucleotide identity relative to the prototype strain VR-759, with amino acid substitutions distributed at discrete positions rather than within extended variable domains, indicating structural conservation. Phylogenetic reconstruction demonstrated that all Riyadh isolates clustered within genotype C, together with previously circulating local strains, supporting sustained endemic persistence and in situ evolution. In silico analysis of the S protein glycosylation landscape identified four invariant N-linked glycosylation motifs (N-X-S/T) at residues 46, 121, 134, and 190, reflecting strong structural constraints on glycan-dependent folding and antigenic configuration. A genotype-associated K68N substitution generated an additional N-glycosylation motif (68NGTD) in multiple Riyadh isolates, potentially modifying local glycan shielding without disrupting the overall glycosylation framework. The preservation of core glycosylation sites alongside selective motif acquisition suggests evolutionary fine-tuning of S surface topology rather than large-scale structural remodeling. Collectively, these findings indicate that genotype C persistence in Riyadh is accompanied by conserved S architecture and subtle glycosylation adjustments that may modulate immune recognition while maintaining structural integrity. Continued high-resolution molecular surveillance will be critical for defining the functional consequences of S microevolution in endemic HCoVs. Full article

Intestinal infections caused by Salmonella enterica serovar Typhi (S. Typhi) remain a global health concern, making preventive strategies and diagnostic tools essential. This study aimed to identify mimotope peptides of the Vi antigen using phage display and assess their recognition by rabbit and 46 human sera, as well as their potential for diagnosis and immunogen design. Rabbits were immunized with the Vi antigen (AgVi) from S. Typhi ATCC 6539, and sera-derived IgG was used for phage biopanning. DNA sequences from selected phagotopes were synthesized as Salmonella mimotope peptides (SMPs), either linear or KLH-conjugated. Their reactivity was tested with ELISAs against AgVi and SMPs, using both rabbit sera and 46 human serum samples. Ten phagotopes were identified, with a consensus motif (D/G–A/V–x–P–x–x–G–x–x–x–x–x), suggesting α-helix structures. Immunization with KLH-conjugated peptides generated specific antibodies, particularly SMPVi/5 and SMPVi/10, which recognized AgVi and their respective peptides. Competitive inhibition assays confirmed that SMPVi/5 reduced the anti-AgVi binding in a dose-dependent manner. In human sera, AgVi recognition occurred in 52% of samples, while SMPVi/5 and SMPVi/10 were recognized in 45%. Overall, SMPVi/5 demonstrated immunogenicity and functional mimicry, supporting its use as a synthetic reagent for serological assays and as a candidate for immunogen design. Full article

Avian influenza infections cause substantial economic losses in the poultry industry and raise public health concerns due to viral adaptation and cross-species transmission. The frequent antigenic drift of influenza viruses further complicates the prevention and treatment of avian respiratory infections. In this study, we generated high-affinity heavy-chain variable domain (VHH) nanobodies from naïve alpaca/camelid VHH libraries using phage display combined with H9N2 influenza A virus (IAV)-infected Madin-Darby Canine Kidney (MDCK) cells. Based on binding affinity and neutralization potential, we identified seven hemagglutinin (HA)-specific and two neuraminidase (NA)-specific VHHs. Molecular docking predicted the interaction sites of HA-specific VHHs (L1-2, L1-4, A5) and NA-specific VHHs (L1-3, L2-2), providing mechanistic insights. Notably, the three HA-specific VHHs (L1-2, L1-4, A5) showed cross-reactivity to representative HA subtypes (H1, H3, and influenza B), indicating recognition of conserved epitopes across divergent influenza strains. For the first time, these camelid nanobodies were fused to the chicken IgY Fc domain, and the expression cassette was integrated into the Saccharomyces cerevisiae genome, achieving a secretion yield of 15–20 mg/L of VHH-Fc antibodies. Experimental validation confirmed that the three HA-specific VHHs-Fc constructs effectively blocked viral infection, while the two NA-specific VHH-Fc constructs (L1-3, L2-2) inhibited NA activity, demonstrating the functional efficacy of the yeast-secreted VHH–IgY Fc platform. This novel IgY Fc fusion approach offers a scalable platform with enhanced stability, extended circulation potential, and applicability in poultry. Full article

Glioblastoma (GBM) remains among the most treatment-refractory human malignancies. It is characterized by profound radioresistance and a highly immunosuppressive tumor microenvironment, limiting the durable efficacy of radiotherapy. Beyond direct cytotoxicity, ionizing radiation can induce immunogenic cell death and the release of damage-associated molecular patterns (DAMPs), including surface-exposed calreticulin, HMGB1, extracellular ATP/adenosine, and tumor-derived DNA. These signals engage pattern-recognition receptors and cGAS–STING–type I interferon pathways, transiently promoting antigen presentation and immune activation. In GBM, however, DAMP signaling frequently evolves toward chronic inflammation and immune suppression, characterized by myeloid cell recruitment, adenosine accumulation, and immune checkpoint upregulation, thereby contributing to tumor regrowth and radioresistance. This dual immune-regulatory role of DAMPs highlights the importance of temporal and contextual interpretation of radiation-induced immune responses. In this review, we summarize current mechanistic and translational evidence on DAMP-mediated immunomodulation in GBM radiotherapy; discuss modality-dependent considerations across photon, proton, and high-LET irradiation; and evaluate the emerging potential of DAMPs as dynamic biomarkers of treatment response. We further outline how integration of DAMP profiling with liquid biopsy, imaging, and nanotheranostic platforms may support biologically informed and adaptive radiotherapy strategies for glioblastoma. Full article

Members of the genus Brucella are bacterial pathogens of global importance, and their increasing detection in marine mammals has raised concerns for wildlife conservation and public health. In this study, we evaluated the biological and pathogenic characteristics of two Brucella sp. sequence type 27 (ST27) isolates obtained from a dwarf sperm whale (Kogia sima). We compared them with terrestrial and marine Brucella reference strains. We assessed resistance to polymyxin B and human serum complement, intracellular infection dynamics in HeLa epithelial cells, persistence in a murine model, and associated hematological and histopathological changes, and analyzed lipopolysaccharide (LPS) profiles. The Kogia isolates exhibited resistance to polymyxin B and serum complement, comparable to that of B. abortus 2308W and marine mammal Brucella strains. In HeLa cells, the isolates displayed distinct, strain-specific intracellular infection dynamics. In the murine model, both isolates persisted in the spleen and induced granulomatous lesions. However, splenic bacterial loads and histopathological scores were generally lower than those observed with B. abortus 2308W, which exhibited the highest virulence among the strains evaluated. Hematological alterations associated with Kogia isolates were also less pronounced than those induced by B. abortus 2308W, indicating an intermediate and strain-dependent virulence phenotype without evidence of enhanced virulence relative to the terrestrial reference strain. Western blot analyses showed that Brucella sp. ST27 isolates were not recognized by anti-B. abortus or anti-O-antigen monoclonal antibodies, while exhibiting a distinct recognition pattern with anti-B. canis serum, indicating differences in surface antigen composition. Comparative whole-genome analysis identified a limited number of isolate-specific variants affecting coding and intergenic regions. Collectively, these findings highlight phenotypic and genetic features of Brucella sp. ST27 from Kogia sima, which distinguishes it from other marine and terrestrial Brucella strains and supports further investigation into its biological behavior and potential public health relevance. Full article

The antigen presentation machinery processes proteins for presentation to T cells, thereby controlling activation of the adaptive cellular immune response. Perturbation of this machinery has been linked to the development of various diseases. This review describes the function of the Major Histocompatibility Complex class I antigen presentation machinery and highlights how its perturbation can lead to compromised immune function and disease progression in the context of cancer. We categorize these perturbations into four distinct mechanistic levels: peptide generation, peptide loading, MHC class I integrity, and epigenetic regulation. This enables an integrated view of their functional impact on immune recognition, supporting therapeutic efforts to target antigen presentation or exploit these alterations in cancer. Full article

Background: Crimean-Congo hemorrhagic fever (CCHF) is a severe tick-borne viral disease with a high fatality rate, and no licensed vaccines are currently available. The nucleoprotein (NP) of the Crimean-Congo hemorrhagic fever virus (CCHFV) plays a critical role in viral replication and immune recognition, making it a promising target for vaccine development. This study aimed to design and evaluate a multiepitope recombinant DNA vaccine targeting the NP of CCHFV. Methods: Cytotoxic T lymphocyte (CTL) epitopes from the NP were predicted via immunoinformatics approaches and systematically assessed for antigenicity, allergenicity, toxicity, hydrophobicity, and global population coverage. The selected epitopes were incorporated into four DNA vaccine constructs driven by a cytomegalovirus promoter, adjuvanted with human β-defensin 3 (hBD3), and fused to the reporter protein mRuby3. The constructs were evaluated in vitro using a fluorescent reporter system designed to provide a readout of TCR signaling upon the co-culture of T lymphocytes with differentiated monocytic cells expressing antigens. In vivo immunogenicity and protective efficacy were assessed in BALB/c (exploratory pilot) and IFNAR^−/− mice, a highly susceptible model for viral infection. Cytokine responses were measured to assess immunogenicity. Results: In vitro assays showed predominantly antigen-independent T-cell activation, suggesting that nonspecific stimulation inherent to the reporter co-culture system likely obscured the detection of antigen-specific TCR signaling. In vivo analyses in BALB/c mice revealed that the constructs elicited only modest systemic cytokine profiles while CCHFV-specific IgG and IFN-γ secretion remained undetectable, indicating that antigen-specific T-cell and antibody responses were limited. In the IFNAR^−/− challenge model, several peptide groups achieved significant 2–3 log reductions in tissue viral RNA and infectious titers (p < 0.05 vs. sham). However, the observed viral modulations were insufficient to reach the protective threshold and did not translate to a survival benefit (0%). Conclusion: Despite a rational in silico foundation, the multiepitope DNA vaccine constructs demonstrated limitations in inducing potent, antigen-specific immunity across both mouse models. The lack of antigen-specific responses indicates limitations in epitope selection, construct design, and delivery strategies, requiring optimization of next-generation epitope-based vaccines. These findings highlight the complexity of translating computational epitope predictions into functional vaccines, and provide benchmark data as a framework to guide future optimizations. Full article

Canine parvovirus (CPV) is a major pathogen causing severe gastroenteritis in dogs. Since its emergence, CPV has undergone continuous evolution, leading to the predominance of variants such as CPV-2a, CPV-2b, and CPV-2c. To characterize the genetic features and evolutionary trends of CPV-2 at a regional level, 775 fecal samples were collected from domestic and stray dogs with suspected CPV-2 infection in Shanghai between 2016 and 2025. The overall positivity rate was 23.2% (180/775); incidence was substantially higher in stray dogs (30.2%) than in domestic dogs (15.9%). Thirty-one CPV-2 strains were successfully isolated. Temporal analysis revealed a pronounced genotype shift: isolates from 2016 to 2020 were predominantly New CPV-2a, whereas CPV-2c became the dominant genotype from 2021 through 2025. Sequence analysis identified the polymorphism of VP2 gene and characteristic mutations F267Y, Y324I, N426E, Q370R and A440T in CPV-2c strains. A novel I447M mutation was detected in several isolates. Phylogenetic analysis showed that Shanghai isolates formed distinct clusters; CPV-2c strains were closely related to the Asian lineage. Structural modeling indicated that mutations at residues L87M, T101I, Y267F, A297S, G300A, Y305D, I324Y, Q370R, N426E, A440T, and I447M may alter the tertiary structure of the VP2 protein, potentially affecting antigenicity and receptor recognition. Collectively, these results demonstrate the complete genotype replacement of CPV-2 in Shanghai; CPV-2c is now predominant. Identification of the novel I447M mutation and structural analysis of key amino acid substitutions provide insight into CPV molecular evolution. These findings suggest that vaccines primarily based on older CPV-2 or CPV-2b genotypes offer suboptimal protection, highlighting the need for updated vaccine strategies targeting prevalent CPV-2c variants. Full article

As a non-invasive mucosal immunization strategy, intranasal vaccines are highly promising for preventing respiratory infectious diseases. Among them, recombinant subunit vaccines represent a safe and ideal option, as they induce targeted mucosal immunity without the safety risks associated with live-vectored or nucleic acid vaccines. However, nasal mucosal defenses rapidly clear antigens before immune activation, limiting protective efficacy. Therefore, intranasal vaccine adjuvants—key regulators of immune response intensity, duration, and type—are essential to overcome mucosal tolerance and improve immunogenicity. Based on a systematic search and analysis of 127 peer-reviewed articles (2010–2026) in PubMed, Web of Science, and Embase, this study comprehensively summarizes the mechanisms, applications, and limitations of existing and candidate adjuvants for intranasal vaccines. This review systematically categorizes and discusses the nasal mucosal barrier, major adjuvant types (e.g., pattern recognition receptor agonists, cytokine adjuvants, and carrier adjuvants), and their mechanisms of action. It also identifies key bottlenecks: insufficient mucosal targeting, inconsistent global safety evaluation standards for adjuvants, and interference from pre-existing antibodies in humans. Furthermore, this review highlights future development directions, including biomimetic adjuvants, pH-responsive nanoadjuvants, and thermostable vaccine formulations. This systematic review clarifies key scientific and technical barriers in intranasal vaccine adjuvant development. The findings provide valuable references for advancing the translation of intranasal vaccines from emergency countermeasures to routine, accessible preventive tools for respiratory infectious diseases. Full article

Porcine reproductive and respiratory syndrome (PRRS) remains one of the most economically devastating diseases in global swine production. The causative agent, PRRS virus (PRRSV), comprises two genetically distinct species—PRRSV-1 and PRRSV-2—that differ substantially in antigenic composition and immune recognition. Despite widespread use of modified live vaccines (MLVs), protection against heterologous and cross-species strains remains inconsistent and difficult to predict. This review synthesizes current knowledge of homologous, heterologous, and cross-species protection, with emphasis on humoral and cellular immune responses and the viral determinants that constrain breadth of immunity. Neutralizing antibodies can confer near-sterilizing homologous protection under controlled conditions; however, their delayed induction and narrow specificity limit efficacy against heterologous strains. T-cell-mediated responses are generally broader but remain highly strain- and context-dependent. Structural features of PRRSV envelope glycoproteins, including glycan shielding and immunodominant decoy epitopes, further restrict antibody-mediated cross-protection while providing targets for rational vaccine design. We also examine potential drawbacks of preexisting immunity, including antigenic mismatch and non-neutralizing antibody-dominated responses that may contribute to suboptimal outcomes following heterologous exposure. Collectively, these findings highlight the multifactorial nature of PRRSV protection and the need for next-generation vaccines capable of inducing broader and more durable immunity. Full article

Scavenger Receptors (SRs) comprise a structurally diverse group of pattern recognition receptors (PRRs) involved in sensing non-self (microbial-associated molecular patterns) or altered-self ligands. CD5 and CD6 are class I SRs (SR-I) preferentially expressed by lymphoid cells and characterized by the presence of several tandem scavenger receptor cysteine-rich (SRCR) domain repeats. Both receptors interact with diverse microbial structures, including tegumental antigens from Echinococcus granulosus sensu lato (s.l.), the cestode parasite responsible for cystic echinococcosis (CE). This is notable as very few PRRs are currently known to detect parasitic helminths and because the infusion of recombinant soluble CD5 and CD6 proteins has shown prophylactic effects in murine secondary CE. Herein, the role of CD5 and CD6 in early immune responses to E. granulosus s.l. tegumental antigens (PSEx) was analyzed using CD5 (Cd5^−/−) and CD6 (Cd6^−/−)-deficient mice. Peritoneal B cells and macrophages from wild-type mice displayed specific and dose-dependent PSEx binding, which was impaired in those from Cd5^−/− and Cd6^−/− mice, supporting direct and/or indirect roles in parasite recognition. Additionally, in vivo exposure of peritoneal exudate cells (PECs) from Cd5^−/− and Cd6^−/− mice to PSEx showed altered activation profiles, including changes in CD80/CD86 expression, impaired early production of natural polyreactive antibodies, and cytokine shift from a Th1/Th17 to a Th2 profile. These findings strongly support the involvement of CD5 and CD6 receptors in the early immune recognition of E. granulosus s.l. antigens by PECs and influence immune responses critical for host resistance, highlighting their relevance in host–parasite interactions. Full article

Influenza A virus remains a major cause of respiratory disease worldwide and poses a persistent challenge to vaccine development due to its rapid genetic evolution and antigenic variability. T-cell-based immunity has therefore gained increasing importance, as it can provide broader and more durable protection by targeting conserved viral regions. Accurate identification of T-cell epitopes (TCEs) is a fundamental requirement for epitope-based vaccine design and immunological research. Although numerous computational methods have been proposed, many existing approaches rely on handcrafted physicochemical features, which offer limited ability to capture contextual sequence dependencies. In this study, a transformer-based viroinformatics framework is proposed for the binary prediction of TCEs from Influenza A virus peptide sequences. The framework employs a pretrained Evolutionary Scale Modeling-2 (ESM-2) protein language model (PLM) to generate rich, contextualized embeddings directly from raw amino acid sequences, eliminating the need for manual feature engineering. These embeddings are processed using a lightweight attention-based transformer classifier to learn epitope-specific sequence patterns. The model achieves strong and stable predictive performance, attaining an accuracy of approximately 97% and an AUC close to 0.99 under stratified cross-validation. Ablation analysis further confirms that protein language model representations and self-attention contribute substantially to performance gains over classical machine learning baselines. To enhance practical reliability, Monte Carlo dropout is incorporated during inference to provide uncertainty-aware predictions, enabling differentiation between high-confidence and ambiguous peptide candidates. In addition, attention-based interpretability is used to identify residue-level contributions to model decisions, offering biologically meaningful insights into epitope recognition. Overall, this study demonstrates that PLMs combined with Transformer architectures provide an effective, interpretable, and a promising computational framework for Influenza A TCE discovery and vaccine research. Full article

Infectious diseases remain a major cause of mortality and disability worldwide. This burden is driven, in part, by antimicrobial resistance (AMR) and the re-emergence of epidemic and pandemic threats, underscoring the need for translational research to address knowledge gaps exposed by recent pandemics. Despite significant advances enabled by antibiotics and antivirals, their effectiveness is increasingly constrained by resistance development, limited pathogen spectra, and prolonged development timelines that fail to keep pace with rapidly shifting epidemiology. Diagnostic limitations impede timely pathogen identification and hinder the development of treatment regimens informed by pathogen mechanisms of action. Severe infections frequently involve dysregulated host responses, including hyperinflammation, inflammasome activation, and endothelial or immunothrombotic injury, which may progress to sepsis, immunoparalysis, or chronic sequelae, highlighting the limitations of pathogen-centered paradigms. Conventional biomarkers and culture-based microbiology are often slow or nonspecific, while molecular assays may not reliably distinguish colonization from active infection or capture host-response heterogeneity shaped by age, immune competence, and disease stage. This review synthesizes mechanistic and translational insights across three interrelated axes: (i) host–pathogen interactions, with a focus on innate immune sensing networks (e.g., Toll-like receptors, inflammasomes, RIG-I-like receptors, and cGAS-STING) and microbial replication and immune evasion strategies; (ii) clinical and public health implications, spanning acute organ dysfunction syndromes, post-acute infection syndromes, and AMR-driven health system strain; and (iii) emerging therapeutics along a continuum of pathogen-, virulence-, host-, and immune-directed approaches. Emphasis is placed on anti-virulence therapeutics, bacteriophage therapy, monoclonal antibodies, and engineered immune modalities within frameworks of quantitative translational pharmacology and implementation science. Finally, an integrative conceptual framework encompassing mechanistic phenotypes, host-response diagnostics, and stage-adapted therapeutic combinations is proposed to guide rational intervention across endemic infections and future pandemic preparedness. Full article

Francisella tularensis, the causative agent of tularemia, is a highly infectious Category A biothreat agent characterized by an exceptionally low infectious dose and diverse transmission routes. Due to the pathogen’s fastidious growth requirements and the high risk of laboratory-acquired infections, traditional cultivation methods are often protracted and hazardous. Consequently, the development of rapid and sensitive diagnostic tools is paramount. This manuscript provides a comprehensive overview of the current landscape of immunoassays, with a specific focus on the evolution from standard laboratory techniques to advanced biosensors. We detail the critical phases of antigen preparation, including high-pressure homogenization and sonication, and the generation of high-affinity polyclonal and monoclonal antibodies. Furthermore, we evaluate the implementation of novel biosensor-like devices, such as electrochemiluminescence and Surface-Enhanced Raman Scattering platforms, designed for point-of-care and field-ready scenarios. By synthesizing recent advancements in nanomaterial-enhanced recognition and microfluidic integration, this review emphasizes the pivotal role of these technologies in achieving early detection and mitigating the impact of both natural outbreaks and potential deliberate misuse of F. tularensis. Full article

Background: Pancreatic ductal adenocarcinoma (PDAC) has one of the poorest prognoses among malignant tumors, mainly due to the difficulty of early diagnosis. Therefore, it is crucial to identify reliable blood markers for a highly sensitive diagnostic system. We previously developed a highly sensitive extracellular vesicle (EV)-counting system, which can quantify the absolute number of specific EVs in serum. In this study, a multiplex assay using lectins that recognize specific glycans on EVs in the serum of PDAC patients was performed to select the optimal lectin combination. Methods: The glycan alteration signature of serum EVs from patients with PDAC was analyzed using a lectin-based multiplex assay combined with the EV-counting system. The optimal lectin combination that recognizes PDAC-specific changes was selected using machine learning analyses (support vector machine) for high diagnostic performance across independent patient cohorts. Results: An optimal lectin combination, Jacalin and Agaricus bisporus agglutinin (ABA), for PDAC detection was identified using machine learning analysis. This lectin-based system, reflecting changes in Jacalin/ABA binding, showed significantly higher diagnostic performance (area under the curve [AUC] = 0.890 and 0.971) than that of the conventional diagnostic marker carbohydrate antigen 19-9 (CA19.9; AUC = 0.752). Notably, the system achieved an AUC of 0.870 in patients with the stage I disease. Conclusions: These findings highlight the potential of a serum EV-based diagnostic system leveraging Jacalin and ABA glycan recognition for the early detection of PDAC. Full article