Search Results (3,476)

Understanding the genetic changes that allow avian influenza A viruses (IAVs) to switch their natural hosts and establish productive infection in humans is important for pandemic risk assessment. Adaptations in the IAV polymerase are required to overcome species-specific restrictions imposed by host ANP32 proteins. Notably, avian virus polymerase is generally only poorly supported by human ANP32 proteins due to species-specific differences. Consequently, efficient polymerase adaptation to the binding interface of human ANP32 requires distinct amino acid changes, such as PB2 E627K. A separate adaptation, PB2 M631L, has recently been reported in mammalian-adapted IAV; however, its functional role across divergent viral lineages and its relationship to host ANP32-dependent adaptation remain incompletely defined. Here, we examine PB2 M631L in the polymerases of a 1918 pandemic strain, a recombinant contemporary H1N1pdm09, and a recent clade 2.3.4.4b H5N1 virus. Using polymerase activity and protein-interaction assays, we show that PB2 M631L enhances polymerase activity and ANP32 binding in human—but not avian—contexts, and that this effect is conserved across multiple viral backgrounds. In H1N1pdm09, PB2 M631L also increased virus replication in mammalian cells. These findings indicate that PB2 M631L contributes to enhanced polymerase compatibility with human ANP32 proteins and are consistent with a role in adaptation across multiple influenza virus lineages. Our results highlight how analysis of historical pandemic strains can inform risk assessment for future emerging viruses. Full article

Background/Objectives: Seasonal waves of respiratory viruses—including SARS-CoV-2, influenza A virus (IAV), and respiratory syncytial virus (RSV)—continue to pose a global health burden and highlight the need for antiviral agents that are effective, safe, broadly active, affordable, and widely accessible. Current interventions are limited by the need for their early administration, the risk of resistance, their costs, and the restricted availability in large parts of the world. For certain natural products, such as European black elderberry (Sambucus nigra L.) fruit extract (ElderCraft^®; EC) and the seaweed-derived sulfated polymer iota-carrageenan (IC), antiviral activities against respiratory viruses, particularly IAV and SARS-CoV-2, have previously been shown. Here, we assessed the antiviral activity of IC and an anthocyanin-standardized EC extract against SARS-CoV-2, IAV, and RSV, either as monotherapy or in multiple-dose combinations. Methods: MDCKII cells were infected with IAV_PR8, human Calu-3 lung epithelial cells with the SARS-CoV-2 Omicron variant, and HEp-2 cells with RSV (A2 strain). Inhibitors were administered either by pre-incubation of cell-free virions prior to infection or, in separate time-of-addition experiments, during or post-infection. Viral replication was quantified by qRT-PCR or intracellular immunostaining. Cytotoxicity was evaluated using a neutral red uptake assay. Results: Most intriguingly, both EC and IC are able to neutralize virions derived from SARS-CoV-2, IAV, or RSV extracellularly in a dose-dependent manner. Notably, EC and IC alone exhibited strong anti-RSV activity, which was not reported previously. Most importantly, combined treatment with IC and EC caused a pronounced synergistic antiviral effect against the tested viruses, as confirmed by the Bliss independence model, without any detectable impact on cell viability. Finally, solutions prepared from matrix-standardized mono- or combi-lozenges, containing IC and/or EC in high or low doses, reproduced the antiviral and synergistic combination effects observed with the pure compounds. Conclusions: In summary, these findings support further development of EC and IC as a topically accessible, virion-neutralizing combination (e.g., lozenges) to provide additional protection against major respiratory viruses and potentially strengthen pandemic preparedness. 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

Aerosols are a major transmission route for seasonal influenza infections. Titanium dioxide (TiO₂) photocatalyst has broad-spectrum antiviral activity, including in vitro influenza virus inactivation; however, whether the TiO₂ photocatalyst can effectively inactivate airborne influenza A viruses in vivo under conditions that mimic natural aerosol transmission remains unclear. Here, we evaluated in vivo inactivation of airborne H1N1 seasonal influenza virus by a photocatalyst-equipped air purifier using a mouse model. Influenza virus WSN strain aerosols were sprayed in a 60 L acrylic box with a nebulizer, circulated through a photocatalyst-equipped air purifier, exposed to BALB/c mice for 40 min after circulation, and subsequently collected with an air sampler. Thirty minutes of TiO₂ photocatalyst treatment reduced influenza virus infectivity by 99.97%, and significantly lowered lung viral titer in mice on day 3 post-infection. Over 14 days post-infection, mice showed no >10% weight loss, 100% survival, and disease progression to the PBS (−) aerosol group. This suggests that the photocatalyst-equipped air purifier may reduce H1N1 seasonal influenza onset, preventing viral spread. Full article

Viral infections remain a global public health challenge. Stimulating the innate immune system is a potent therapeutic strategy that promotes pathogen clearance, directly impacting disease severity and clinical outcomes. Interferons and interferon-stimulated genes (ISGs) are critical components of this antiviral defense system. Neomycin, an aminoglycoside antibiotic, can induce ISG expression and help establish an antiviral state. In this study, we demonstrated that neomycin induces the production of pro-inflammatory cytokines (IL1β, TNFα, IL6, GM-CSF, and IFN-γ) in peripheral mononuclear blood cells (PBMCs) and activates key antiviral ISGs, including MxA, OAS1, and IRF7. The protein expression profiles elicited by neomycin were comparable to those induced by poly(I:C). Intranasal delivery of neomycin to CBA and BALB/c mice induced various ISGs in both the respiratory tract and splenic tissues. Prophylactic administration of neomycin significantly inhibited influenza B virus replication in the lung and nasal turbinates of CBA mice in a sublethal infection model. Overall, our data suggest that neomycin, when used prophylactically alone or combined with other antiviral strategies, shows considerable potential for the attenuation of influenza B virus infections. Full article

Influenza viruses are significant causes of acute respiratory infections, often leading to severe health issues and mortality. These viruses undergo continuous mutations and genetic reassortments, resulting in annual epidemics and potential pandemics. The A(H3N2) strains exhibit high genetic and antigenic variability, that influence vaccine efficacy. This study aimed to assess the prevalence of influenza viruses, including A(H3N2) strains, in Kazakhstan during 2020–2025. The study used nasopharyngeal swab and serum samples obtained from patients. The presence of influenza virus antigens in nasopharyngeal swabs was analyzed using real-time polymerase chain reaction. The level of specific antibodies in the blood serum was determined using the hemagglutination inhibition reaction and enzyme-linked immunosorbent assay methods. Influenza A/H1N1, A/H3N2 and B viruses were diagnosed using real-time PCR. Antibodies to A/H1N1pdm09, A/H3N2 and B were detected in serological studies. Our studies revealed a trend toward seasonal patterns in influenza A viruses circulation. Therefore, it was established that the A/H3N2 strains dominated in Kazakhstan during the 2021–2022 and 2023–2024 epidemic seasons. The 2023–2024 strains belong to the specific genetic clade J.2 or 3C.2a1b.2a.2a.3a.1. These studies confirmed the role of influenza viruses in the etiology of respiratory infections and emphasized the need to continue monitoring their spread in Kazakhstan. Full article

Understanding how viruses engage host cell surfaces is fundamental to infection biology and therapeutic development. While vaccines remain central to prevention, recent global crises have emphasized the need for complementary antiviral strategies that can be mobilized rapidly against both known and emerging pathogens. In this context, artificial intelligence (AI) systems for biomolecular structure prediction, culminating in AlphaFold 3, are reshaping what is experimentally and conceptually achievable. Here, we present “Interactys-AI”, a framework designed to exploit AI-based structural modeling to systematically map virus–host protein–protein interactions (PPIs) and connect them to actionable drug repurposing opportunities. Beyond a technical workflow, Interactys-AI reflects a broader transformation toward predictive and anticipatory antiviral discovery. We describe the conceptual foundations of the platform, its implementation, and its application to influenza A H5N1 hemagglutinin. We further discuss how structural AI may redefine preparedness strategies, highlight current limitations, and outline future directions toward real-time therapeutic hypothesis generation. Full article

Background: In complex biological processes, there exists a tipping point (pre-disease state) when the system undergoes a sudden and dramatic shift to a contrasting state. Accurate detection of the pre-disease state is critical for preventive medicine. However, precise detection of the pre-disease state proves challenging due to the clinical single-sample problem. Methods: To address this challenge, in this study, we introduce a novel single-sample pre-disease state detection method based on the change in local network enrichment level. Results: We validated the proposed method on five independent real datasets, including one influenza virus infection time-course dataset and four tumor datasets. Experimental results confirmed that the proposed method can accurately identify the pre-disease state prior to overt disease onset. Further analysis verified key genes identified by the proposed method in pre-disease state are associated with viral infection and immune dysregulation for the influenza dataset, and tumor metastasis for the tumor datasets. Conclusions: These results demonstrate that this method is a robust and biologically interpretable tool for single-sample pre-disease state detection, with great potential for clinical translation in individualized preventive medicine. Full article

Highly pathogenic avian influenza virus (HPAIV) H5N1 has been detected in dairy cattle in the United States, with high viral loads observed in milk from infected animals. This raises public health concerns regarding potential transmission through exposure to raw milk. The sale of raw milk via vending machines represents a well-established distribution model in many European countries, including Switzerland. Although a notice must be posted on these milk vending machines stating that it is raw milk, together with appropriate processing instructions (heating to over 70 °C required, storage below 5 °C, consumption within 3 days), these notices are sometimes missing, and consumers often do not follow these guidelines. Over a four-month period, spanning from June 2025 to September 2025, 124 raw milk samples were collected from vending machines across Switzerland. Samples were screened for influenza A using reverse-transcription quantitative PCR (RT-qPCR). No samples tested positive for influenza A virus. The data from this study demonstrate the feasibility of implementing a sampling and detection system for HPAIV H5N1 in direct-to consumer raw milk samples and highlight the currently very low risk of HPAIV in raw milk samples sold via vending machines in Switzerland. Full article

Background/Objectives: Transmembrane serine proteases such as TMPRSS2 and matriptase have been identified as pivotal host factors in the influenza A infection due to their capacity to cleave the hemagglutinin and thereby facilitate viral activation. The inhibition of these enzymes has the potential to serve as an effective therapeutic strategy against numerous seasonal influenza strains. In our study, four 3-amidinophenylalanine-derived inhibitors were used to elucidate their antiviral efficacy, pharmacokinetic properties and affinities toward certain related trypsin-like serine proteases. Methods: K_i values for TMPRSS2, matriptase, thrombin and factor Xa were determined using enzyme kinetic measurements. Cytochrome P450 3A (CYP3A) inhibitory activity was investigated using human liver microsomes, and protein binding was evaluated with human serum albumin and α₁-acid glycoprotein. In vitro antiviral efficacy and cytotoxicity were determined in MDCK-II cells. Results: All compounds were non-cytotoxic and exhibited a relatively high affinity toward matriptase and bovine thrombin in the 10–30 nM concentration range. Among the inhibitors, MI-441 displayed the lowest K_i value for TMPRSS2 (~60 nM). The weakest CYP3A inhibitory activity was observed for compounds MI-447 and MI-448. In addition, three of the four compounds (MI-441, MI-443 and MI-447) demonstrated significant antiviral activity. Conclusions: This study demonstrates that the investigated inhibitors exhibit a favorable safety profile, low binding to human serum albumin and pronounced antiviral activity against H1N1. Full article

Vaporized free chlorine, primarily present as hypochlorous acid (HOCl), is increasingly used for indoor microbial control; however, virus-dependent susceptibility and its molecular determinants remain unclear. We evaluated virucidal effects under controlled indoor conditions (0–9 ppb) against echovirus 30 (E30), influenza A/H1N1, and human adenovirus type 3 (HAdV3). Infectious titers were quantified by TCID₅₀ assays. Computational fluid dynamics (CFD) simulations and gas-sensor measurements assessed spatial dispersion, and structural analyses examined oxidation-sensitive amino acid residues. Significant reductions in infectivity were observed for E30 (99.0%, p = 0.00727) and influenza A/H1N1 (99.9%, p = 0.000597), whereas no significant reduction was detected for HAdV3 (p = 0.142). Analyses including all data points without outlier exclusion confirmed the robustness of these findings. CFD indicated uniform dispersion, although spatial heterogeneity within the indoor environment cannot be excluded. These findings suggest that viral susceptibility to vaporized HOCl is associated with residue-level composition and structural context; however, this relationship should be interpreted as correlative rather than causal. Moreover, integration of molecular and structural analyses provides a plausible mechanistic framework, although direct biochemical validation remains necessary. Structural analyses showed lower proportions of oxidation-sensitive residues in adenoviral proteins compared with influenza A hemagglutinin (OR = 0.34–0.40, adjusted p < 0.001) and the E30 VP1 intermediate. Residues were clustered in surface-exposed functional domains in susceptible viruses. Full article

The receptor for advanced glycation end-products (RAGE) is a lung-enriched pattern recognition receptor implicated in inflammatory responses. Its role in ferroptosis-mediated lung injury during viral infection, however, remains unclear. Here, we combined bioinformatics analysis with in vitro and in vivo experimental validation to investigate the RAGE–ferroptosis axis in influenza virus infection. Cross-analysis of RAGE- and ferroptosis-related genes identified overlapping candidates, suggesting functional crosstalk. Influenza-infected A549 cells exhibited ferroptotic cell death, characterized by Fe²⁺ accumulation, reactive oxygen species (ROS) elevation, and lipid peroxidation, which was markedly attenuated by the RAGE inhibitor FPS-ZM1. In A/PR/8/34 (H1N1)-infected female C57BL/6J mice, FPS-ZM1 treatment improved survival, reduced lung injury, restored redox balance, and modulated key ferroptosis regulators ACSL4, POR, and GPX4. Moreover, RAGE inhibition decreased M1 macrophage and neutrophil infiltration and reduced pro-inflammatory cytokines. Collectively, these findings reveal that RAGE activation drives ferroptosis and amplifies oxidative stress–associated lung injury, whereas RAGE inhibition mitigates tissue damage via the ACSL4/POR/GPX4 pathway and immunomodulation. This study identifies the RAGE–ferroptosis axis as a potential therapeutic target for severe pulmonary inflammation. Full article

Seasonal influenza A evolves quickly through mutations in haemagglutinin (HA) and neuraminidase (NA), which can reduce vaccine match and lower protection. Many sequence-only models do not link codon-level mutations to three-dimensional (3D) protein context and long-term evolutionary signals within one scoring framework. This study presents TRIAD-Influenza (TRIAD: Token–Residue–Integrated Architecture for Drift), a multi-view transformer that combines (i) codon- and residue-level sequence representations, (ii) structure-derived residue interaction features from predicted HA/NA models, and (iii) an embedding-space phylogeny that captures cluster and drift context. The pipeline curates more than $3\times {10}^5$ paired HA/NA coding sequences from the NCBI Virus resource (2010–2024) using strict quality control and codon-aware alignment and predicts 3D structures for nearly all unique HA and NA proteins to build contact graphs and surface/stability descriptors. TRIAD-Influenza outputs a continuous, structure-aware risk score for each HA/NA pair and produces interpretable mutation hotspot maps using gradient saliency and a contact-weighted mutation risk index (CMRI). On rolling-origin temporal cross-validation and for a temporally held-out internal test window with strong class imbalance (∼3.4% high-risk), the model shows strong ranking performance (AUROC $\approx 0.89$; AUPRC $\approx 0.44$; Brier score $=0.069$) while operating at surveillance speed (median latency $\approx 1.6$ ms per HA/NA pair). External validation on independent GISAID/Nextstrain cohorts (2023–2024; 5000 isolates) preserves discrimination (AUROC $\approx 0.85$–$0.86$). Predicted risk scores correlate with experimental haemagglutination inhibition (HI) antigenic distances (Spearman $\rho$ up to ≈0.82 at the virus-aggregated level), and CMRI hotspots enrich known epitope and deep mutational scanning escape residues (odds ratios $\approx 2.7$–$3.6$). Overall, token–residue–phylogeny coupling enables rapid, structure-aware prioritisation of emerging influenza A HA/NA sequences and delivers compact hotspot maps for expert review and targeted experiments. Full article

The coronavirus disease 19 pandemic disrupted pediatric respiratory infections through non-pharmaceutical interventions and altered contact patterns. Long-term comparisons across the pandemic timeline in children remain limited. In this study, we analyzed 15,657 respiratory specimens from patients ≤ 18 years at Dankook University Hospital (2007–2023) using multiplex polymerase chain reaction assays targeting 15 viruses. Age-stratified positivity rates were compared across pandemic phases. Children ≤ 6 years comprised 88.61% of the study population. Human rhinovirus showed the highest detection rate (24.06%), followed by adenovirus (12.33%), respiratory syncytial virus-subtypes A and B (RSV-A: 11.13%; RSV-B: 8.65%), human parainfluenza virus-type 3 (HPIV-3; 6.21%), human metapneumovirus (HMPV; 5.33%), and enterovirus (2018–2023; EV; 10.96%). Monthly distributions differed (p < 0.001). RSV peaked in late autumn and winter; influenza and seasonal coronaviruses in winter and spring; HMPV, HPIV-3, EV, and human bocavirus in summer and fall. Positivity declined during the pandemic, rebounding in 2023, most prominently among children aged 1–6 years (84.91%). HPIV-3 and EV increased (p < 0.001). RSV-A predominated pre-pandemic, whereas RSV-B showed a non-significant relative increase post-pandemic; no subtype differences occurred during the pandemic. Findings demonstrate pathogen-specific shifts in predominance and seasonality and support ongoing surveillance and pediatric care planning. Full article

Background/Objectives: Vaccination against respiratory viruses—such as respiratory syncytial virus (RSV), pneumococcal disease, influenza, and COVID-19—may reduce the risk of adverse outcomes in older adults with cardiovascular disease. This study conducted a scoping review of the effects of respiratory vaccines in older adults with cardiovascular disease. Methods: We included studies evaluating adults aged ≥ 60 years with cardiovascular disease who received different types of respiratory vaccines. Eligible designs comprised clinical trials, observational cohort studies, and other relevant studies. Editorials, commentaries, and non-original publications were excluded. A comprehensive and targeted literature search was conducted in PubMed, Scopus, EMBASE, and Web of Science from database inception through January 2026. Results: A total of 25 studies were included, encompassing 1,782,787 adults aged ≥ 60 years with cardiovascular disease who received various respiratory vaccines. RSV vaccines were associated with a lower incidence of cardiorespiratory hospitalization and stroke among vaccinated individuals. Pneumococcal vaccines showed that sequential dual vaccination strategies were associated with a lower risk of cardiovascular events. Influenza vaccination was associated with improved cardiovascular outcomes, lower mortality, and reduced adverse events. COVID-19 vaccines were associated with reductions in mortality and hospitalizations. These benefits are particularly relevant in an older population with a high burden of comorbidities; therefore, complete vaccination schedules, including booster doses, should be considered a central strategy for prevention and comprehensive management in this high-risk group. Conclusions: Vaccination against respiratory viruses in older adults with cardiovascular disease demonstrates an overall favorable/acceptable profile of efficacy and safety, with reductions in mortality, hospitalizations, and cardiovascular events, without a significant increase in serious adverse events. Full article