Search Results (954)

Influenza A virus (IAV) infection triggers excessive activation of PANoptosis—a coordinated form of programmed cell death integrating pyroptosis, apoptosis, and necroptosis—which contributes to severe immunopathology and acute lung injury. However, the molecular regulators that drive PANoptosis during IAV infection remain poorly understood. In this study, we integrated bulk and single-cell RNA sequencing (scRNA-seq) datasets to dissect the cellular heterogeneity and transcriptional dynamics of PANoptosis in the influenza-infected lung. PANoptosis-related gene activity was quantified using the AUCell, ssGSEA, and AddModuleScore algorithms. Machine learning approaches, including Support Vector Machine (SVM), Random Forest (RF), and Least Absolute Shrinkage and Selection Operator (LASSO) regression, were employed to identify key regulatory genes. scRNA-seq analysis revealed that PANoptosis activity was primarily enriched in macrophages and neutrophils. Integration of transcriptomic and computational data identified cathepsin B (CTSB) as a central regulator of PANoptosis. In vivo validation in an IAV-infected mouse model confirmed elevated expression of PANoptosis markers and upregulation of CTSB. Mechanistically, CTSB may facilitate NLRP3 inflammasome activation and promote lysosomal dysfunction-associated inflammatory cell death. These findings identify CTSB as a critical mediatoCTSBr linking lysosomal integrity to innate immune-driven lung injury and suggest that targeting CTSB could represent a promising therapeutic strategy to alleviate influenza-associated immunopathology. Full article

H5N1 Influenza A virus continues to pose a significant zoonotic threat, with increasing evidence of interspecies transmission and genetic adaptation. Previous studies primarily focused on avian or human isolates, with limited comprehensive analysis of H5N1 evolution across multiple mammalian hosts. Existing molecular surveillance often lags behind viral evolution; this study underscores the necessity for real-time monitoring of ongoing mutations affecting pathogenicity and transmissibility. Our goals are (1) to retrieve and analyze HA, NP and NA gene sequences of H5N1 Influenza A virus from diverse hosts, including humans, poultry and multiple mammalian species, to assess genetic diversity and evolutionary patterns and (2) to evaluate positive selection sites across the three major genes (HA, NP and NA) to determine adaptive mutations linked to host adaptation and viral survival. To achieve these goals, in this study, we considered (78 HA), (62 NP) and (61 NA) gene sequences from diverse hosts, including humans, poultry and multiple mammalian species, retrieved from the NCBI database. Phylogenetic analysis revealed distinct clade formations, indicating regional spread and cross-species transmission events, particularly from avian sources to mammals and humans. Selection pressure analysis identified positive selection across all three genes, suggesting adaptive mutations contributing to host adaptation and viral survival. Homology modeling and molecular dynamics simulations were performed to generate high-quality structural models of HA, NP and NA proteins, which were subsequently validated using multiple stereochemical parameters. Domain analysis confirmed conserved functional motifs, while protein–ligand docking demonstrated stable interactions at conserved binding sites, despite observed residue substitutions in recent isolates. Earlier research concentrated on HA alone; this study integrates HA, NP and NA genes for a broader understanding of viral evolution and adaptation. These findings highlight ongoing evolutionary changes in H5N1 genes that may enhance viral adaptability and pathogenicity, underscoring the need for continuous molecular surveillance and updated antiviral strategies. Full article

Background: Influenza A virus (IAV) is a major human pathogen, contributing to substantial morbidity and mortality during seasonal outbreaks and pandemics. Human infection with IAV can lead to pneumonia and acute respiratory distress syndrome (ARDS), and numerous clinical and basic research studies have established an association between IAV and pulmonary fibrosis (PF). However, the treatment of IAV-induced PF fibrosis has not been studied and discussed. Methods: An IAV-induced PF mouse model was established. Herbacetin (HBT) was identified as the most effective compound in the in vitro study of seven components of Rhodiola rosea L. (R. rosea L.). The effect of HBT on IAV-induced lung injury and PF was evaluated in vivo and in vitro. The binding between HBT and neuraminidase (NA) protein was investigated by biological layer interferometry (BLI) and cell thermal shift assay (CETSA). Results: Following IAV infection, the TGF-β/Smad3 pathway is activated, leading to the upregulation of fibrosis-related proteins that promote fibrosis. HBT exhibited a significant ability to reduce influenza virus-induced lung injury and fibrosis both in vitro and in vivo. Mechanistically, HBT binds to the NA protein of the influenza virus, reducing viral infection and the activation of the TGF-β/Smad3 pathway, thereby mitigating the formation of lung injury and PF. Conclusions: HBT represents a promising therapeutic agent for modulating influenza virus-induced lung injury and PF, marking a significant step toward the development of effective treatments for influenza-induced PF. Full article

Background/Objectives: Avian influenza represents a major threat to both animal and public health. Our group has tracked avian influenza viruses circulating in wild birds in Peru during the last 20 years. While most of these viruses are low-pathogenic avian influenza strains, some exhibit genetic changes that significantly diverge from common circulating viruses. We selected a highly divergent hemagglutinin H2 gene from a genetically characterized avian influenza virus to develop a recombinant protein using a baculovirus system. Methods: We administered 5 µg and 20 µg doses of the recombinant H2 protein (rH2) into 3-week-old chickens using an abdominal cavity inoculation model to evaluate the activation of innate immune responses. Chickens were euthanized at 24 and 72 h post inoculation and an abdominal lavage was performed to harvest the abdominal cavity content. Results: Infiltrating cells were counted and their cell viability was measured using an Annexin V/PI staining. At 24 h, a large proportion of infiltrating leukocytes were identified as heterophils, monocyte/macrophages and lymphocytes. These proportions changed at 72 h, with a decrease in heterophils and increase in monocyte and lymphocyte pools. We observed strong cellular activity in abdominal leukocytes at 24 h, with a decline in activation levels at 72 h. Cytokine expression suggested a tightly regulated immune response during the 72 h period, while a more sustained response was observed at the 20 µg dose. Antibody levels demonstrated the capacity of the rH2 protein to induce long-term responses. Conclusions: These results revealed that the baculovirus-expressed rH2 protein induces a controlled immune activation, a long-term immune response, holding promise as a potential vaccine candidate for animal health. Full article

Background: Haemophilus influenzae (Hi), a Gram-negative bacterium, is divided into two broad categories: encapsulated and non-capsulated isolates, also called non-typeable Hi isolates (NTHi). NTHi has become prevalent since the introduction of the vaccine against Hi of serotype b. Hi can cause local infections on respiratory mucosal surfaces and urogenital infections, which can lead to septic abortion in pregnant women. It can also cause invasive infections such as meningitis and septicemia. Moreover, NTHi isolates are becoming increasingly resistant to antibiotics. Vaccines targeting NTHi are not yet available. As these NTHi isolates are not encapsulated, vaccines should target proteins at the bacterial surface. However, vaccine development is hindered by the high variability of these proteins. We aimed to identify conserved outer membrane proteins (OMPs) for vaccines against NTHi. Methods: We analyzed core-genome multilocus sequence typing (cgMLST) of 1144 genomes of Hi collected between 2017 and 2022 and, of these, identified 514 conserved genes that encoded OMPs. We focused on two specific OMPs: Haem1295, encoding the protein P5 (P5), and Haem1040, encoding the protein 26 (P26). P5 is known to bind human complement regulatory protein factor H (FH), while both P5 and P26 are involved in enhancing immune responses. The genes encoding these proteins were cloned, overexpressed, purified, and tested in both active and passive protection models using systemic infection in mice. Results: P5 and P26 were found to be immunogenic during human infections. Vaccination with these proteins conferred protection against both homologous and heterologous NTHi isolates in mice, suggesting broad cross-protection. Conclusions: P5 and P26 are promising vaccine candidates showing cross-protection against NTHi and offering the additional benefit of targeting bacterial virulence factors, enhancing vaccine efficacy against NTHi isolates. Full article

Background and Objectives: Kumazasa extract (KZExt) is a food product obtained by steam extraction of Kumazasa (Sasa senanensis and Sasa kurilensis) leaves under high temperature and pressure. It contains abundant polyphenols, including trans-p-coumaric acid and ferulic acid, as well as xylooligosaccharides. In this study, we investigated the antibacterial, anti-viral, and anti-inflammatory effects of KZExt in vitro and in vivo. Materials and Methods: The anti-oxidant, antibacterial, and anti-viral effects of KZExt were assessed in vitro. Anti-oxidant activity was evaluated based on the scavenging of •OH, •O₂⁻ and ¹O₂. Antibacterial effects were assessed by determining the minimum inhibitory concentration (MIC) using a microdilution method. Anti-influenza activity was measured via plaque formation in MDCK cells. Anti-inflammatory effects were assessed by measuring interleukin (IL)-1β inhibition in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. In vivo, KZExt was administered once (30 min before) in a formalin-induced inflammation model to evaluate pain-related behavior. In the LPS-induced inflammation model, KZExt was administered for five days before LPS injection. Behavioral changes and cytokine levels were assessed 24 h later via the open field test and cytokine quantification. Results: In vitro, KZExt showed antibacterial, anti-influenza, and anti-oxidant effects, and suppressed LPS-induced IL-1β production. In vivo, it significantly reduced the second phase of formalin-induced pain behavior. In the LPS model, although behavioral changes were unaffected, KZExt suppressed IL-6 and interferon-γ production. Conclusions: The antibacterial, anti-viral, and anti-inflammatory effects of KZExt were confirmed in vitro and in vivo. Notably, the anti-inflammatory effect suggests potential immunomodulatory activity. These findings indicate that KZExt may help suppress smoldering inflammation and inflammation associated with various diseases through its combined antibacterial, anti-viral, and immunomodulatory actions. Full article

Objective: This study aims to investigate the pharmacodynamic effects and underlying mechanisms of the Chinese herbal formula RuHaoDaShi (RHDS) granules against the influenza virus in experimental models. Methods: This study aims to employ network pharmacology to identify the active components of RHDS and its potential targets and mechanisms of action against H1N1. The molecular docking approach validated the interactions between the core targets and the RHDS compounds. In vitro, the antiviral activity of RHDS was assessed by therapeutic, prophylactic, and premixed administration to H1N1-infected A549 cells. An in vivo experiment was conducted using a mouse H1N1 pneumonia model. The model was treated with a dose of 1.04, 2.08, and 4.16 g/kg of RHDS, administered via gavage daily. The study’s objective was to evaluate the antiviral activity and mechanism of action of RHDS in mice. Mice were evaluated on day 6 by assessing survival, viral load (RT-qPCR), lung pathology (HE staining), inflammatory cytokines (ELISA, immunohistochemistry), and ferroptosis markers (WB, qPCR). Results: Network pharmacology identified 77 biologically active RHDS compounds (e.g., quercetin and kaempferol) and 32 core targets common to RHDS, H1N1, and ferroptosis. Molecular docking was used to verify a high affinity for binding between the core targets HIF-1α, MAPK3, and key RHDS compounds. In vitro studies demonstrated that RHDS exhibited protective properties against H1N1-infected cells, with the therapeutic delivery method proving the most efficacious. In vivo studies have shown that RHDS reduces mortality, lung index, and viral load in mice while attenuating histopathological damage. The study demonstrated a reduction in the release of inflammatory cytokines, including IL-6, IFN-γ, and IL-17A, and decreased expression levels of MPO and F4/80 proteins in lung tissue. Mechanistically, the administration of RHDS resulted in the up-regulation of the expression levels of GPX4, SLC7A11, and Nrf2 proteins while concomitantly inhibiting the expression of HIF-1α, COX2, and ACSL4. These findings confirm the modulatory effect of RHDS on the GPX4/SLC7A11/Nrf2 pathway. Conclusions: RHDS demonstrated a protective effect against H1N1-induced cytopathy in vitro and was effective in attenuating H1N1-induced pneumonia in murine models. The study suggests that RHDS has antiviral potential to treat H1N1 viral pneumonia by modulating inflammatory cytokines and the GPX4/SLC7A11/Nrf2 pathway. Full article

Background: Influenza vaccine and pneumococcal vaccine are essential to protect the health of older adults. This study focuses on the impact of family physicians’ recommendations on influenza and pneumococcal vaccine uptake among urban Chinese older adults and makes recommendations for improving vaccination rates. Methods: A cross-sectional survey on influenza vaccination and pneumonia vaccination was conducted in December 2024 in six cities in China among adults aged ≥60 years. Marginal effects as well as logistic regression models were adopted to measure the relationship between family physician recommendation and influenza vaccination and pneumonia vaccination. Results: The overall influenza vaccination rate was 34.05% and pneumococcal vaccination rate was 22.79%. City, educational level, monthly income, health status, and family physician vaccination recommendation had significant impacts on influenza and pneumococcal vaccination (p < 0.05). Among the investigated elderly population, 48.78% and 28.56% had received recommendations from family physicians regarding influenza and pneumococcal vaccination, respectively. Analysis of marginal effects models revealed that physicians’ recommendations were significantly able to boost influenza and pneumococcal vaccination rates by 26.3% (average marginal effect = 0.263, 95% CI = 0.249–0.277) and 23.7% (average marginal effect = 0.237, 95% CI = 0.225–0.248), respectively (p < 0.001). In the adjusted model, family physician recommendation, compared with no family physician recommendation, was also associated with vaccine policy, monthly income, and age in influenza vaccine and pneumococcal vaccine uptake. Conclusions: Older adults’ influenza and pneumococcal vaccination rates need to be improved. Family physicians’ recommendations show a more significant impact on older adults. Family physician recommendations had the greatest boosting effect on vaccination among individuals aged 70–79. Healthcare providers should adopt different vaccine recommendation strategies based on the characteristics of older adults. Full article

Avian influenza (AI), particularly the H5 subtypes, poses a significant and persistent threat globally. While the influence of environmental factors on AI seasonality is recognized, a comprehensive understanding of the hierarchical and interactive effects of multi-scale drivers in a vast and ecologically diverse country like China remains limited. We developed an interpretable machine learning framework (XGBoost with SHAP) to analyze the spatiotemporal risk of 1800 H5 AI outbreaks in mainland China from 2000 to 2023. We integrated multi-source data, including dynamic poultry density, Köppen climate classifications, Important Bird and Biodiversity Areas (IBAs), and daily meteorological variables, to identify key drivers and quantify their nonlinear and synergistic effects. The model demonstrated high predictive accuracy (5-fold cross-validation $R^2$ = 0.776). Our analysis revealed that macro-scale ecological contexts, particularly poultry density and specific Köppen climate zones (e.g., Cwa), and strong seasonality were the most dominant drivers of AI risk. We identified significant nonlinear relationships, such as a strong inverse relationship with temperature, and a critical synergistic interaction where high temperatures substantially amplified risk in areas with high poultry density. The final predictive map identified high-risk hotspots primarily concentrated in eastern and southern China. Our findings indicate that H5 AI risk is governed by a hierarchical interplay of multi-scale environmental drivers. This interpretable modeling approach provides a valuable tool for developing targeted surveillance and early warning systems to mitigate the threat of avian influenza. Full article

Clinical evidence has associated H1N1 influenza with liver impairment, yet the underlying mechanisms remain poorly understood. Here, we investigated H1N1-induced liver damage and its potential mechanisms using a BALB/c mouse infection model. Pathological examination and serum aspartate transaminase (AST) and alanine transaminase (ALT) were assessed. Messenger ribonucleic acid-sequence was used to analyze the transcriptomic changes in tissues. Multiple inflammatory cytokines in tissues and inflammatory cells in the blood were detected on the fifth day post-infection. Our results showed that H1N1 infection caused significant liver pathology and elevated serum AST/ALT levels. Transcriptomic analysis revealed significant alterations in liver gene expression profiles following H1N1 infection, particularly in genes associated with inflammatory responses, including those involved in monocyte adhesion/activation and neutrophil/macrophage infiltration. Marked increases in inflammatory mediators were observed in lungs, serum, and liver, accompanied by systemic changes in circulating inflammatory cells, indicating H1N1 triggered a robust systemic inflammatory response. These findings suggest that H1N1-induced liver damage may be associated with the systemic inflammatory response induced by H1N1 and changes in liver gene regulation. Full article

Influenza viruses are major threats to global health, with potential to cause widespread disease in both humans and animals. Cattle, once considered resistant, are susceptible hosts for multiple influenza viruses, including influenza A, C and D, while no evidence currently supports infection with influenza B virus. Cattle serve not only as natural reservoirs for influenza D virus but also as emerging spillover hosts for highly pathogenic avian influenza A strains like H5N1. Their role in sustaining viral circulation, facilitating interspecies transmission, and potentially contributing to viral evolution raises significant concerns about future global outbreaks. As host immunity controls viral clearance and spread, understanding how cattle respond to influenza is essential. While most research has focused on antibody-mediated immunity, T cells play indispensable roles in controlling influenza infections by regulating antibody response, clearing infected cells, and providing long-term protection. However, bovine T cell responses to influenza remain poorly characterized. Given that most research has focused on mice and humans, this review outlines current knowledge of bovine T cell responses to influenza viruses in comparison to these well-characterized models. Cross-species comparative studies are essential to identify species-specific immunity, guide cattle vaccine development, and build predictive models to evaluate future pandemic potential. Full article

Background/Objectives: Influenza represents a significant burden on global public health, and vaccination is the most effective strategy to reduce it. The large investment in vaccination programs and the need for adjustments in vaccine serotypes are important reasons for evaluating the influenza vaccine’s efficacy every year. Establishing a relationship between immunogenicity data and efficacy is also crucial for predicting the efficacy of a vaccine during its development. Antibody response measurement is one of the most common methods for evaluating immunogenicity, particularly in vaccines and biologics. The aim of this systematic review was to define a model that relates the immunogenicity of a given vaccine to its efficacy, based on hemagglutination inhibition titer levels. Methods: To achieve this goal, information was gathered from articles linking immunogenicity with the efficacy of the influenza vaccine in the Medline and Scopus databases. Different mathematical models were developed and applied to assess the relationship between HAI titers and the effectiveness of the flu vaccine. This analysis was conducted for the various existing vaccines, for the different influenza virus strains, and for their efficacy in paediatric populations. Results: The r² obtained ranged from 0.2579 to 0.966, which points to the importance of this immunological factor in the efficacy of the influenza vaccine. Conclusions: The efficacy values for titer level 40 confirm the validity of the data provided by Hobson. Full article

In this paper we aimed to compare seasonality, clinical characteristics, and outcomes of Influenza A and COVID-19 in the context of influenza reemergence and ongoing Omicron circulation. We performed a retrospective comparative analysis at the Teaching Hospital of Infectious Diseases in Cluj-Napoca, Romania. We included adult patients hospitalized with Influenza A or COVID-19 between 1 November 2022 and 31 March 2024. Data were collected on demographics, clinical presentation, complications, and in-hospital mortality. We included 899 COVID-19 and 423 Influenza A patients. The median age was 74 years for COVID-19 and 65 for Influenza A (p < 0.001). The age-adjusted Charlson comorbidity index was higher in COVID-19 patients (5 vs. 3, p < 0.001). Despite this age gap, acute respiratory failure was more common in Influenza A (62.8% vs. 55.7%, p = 0.014), but ventilation rates did not differ significantly. Multivariate models showed Influenza A was associated with increased risk of intensive-care unit (ICU) admission or ventilation, whereas older COVID-19 patients had higher in-hospital mortality (5.67% vs. 3.3%, p = 0.064). Omicron COVID-19 disproportionately affected older patients with comorbidities, contributing to higher in-hospital mortality. However, Influenza A remained a significant driver of respiratory failure and ICU admission, underscoring the importance of preventive measures in high-risk groups. Full article

Highly pathogenic avian influenza (HPAI) remains a persistent threat to global poultry production and public health. Current vaccine platforms show limited cross-clade efficacy and often fail to induce mucosal immunity. Recent advances in microbiome research reveal critical roles for gut commensals in modulating vaccine-induced immunity, including enhancement of mucosal IgA production, CD8⁺ T-cell activation, and modulation of systemic immune responses. Engineered commensal bacteria such as Lactococcus lactis, Bacteroides ovatus, Bacillus subtilis, and Staphylococcus epidermidis have emerged as promising live vectors for antigen delivery. Postbiotic and synbiotic strategies further enhance protective efficacy through targeted modulation of the gut microbiota. Additionally, artificial intelligence (AI)-driven tools enable predictive modeling of host–microbiome interactions, antigen design optimization, and early detection of viral antigenic drift. These integrative technologies offer a new framework for mucosal, broadly protective, and field-deployable vaccines for HPAI control. However, species-specific microbiome variation, ecological safety concerns, and scalable manufacturing remain critical challenges. This review synthesizes emerging evidence on microbiome–immune crosstalk, commensal vector platforms, and AI-enhanced vaccine development, emphasizing the urgent need for One Health integration to mitigate zoonotic adaptation and pandemic emergence. Full article

Avian influenza A viruses (IAVs) pose a persistent threat to the poultry industry, causing substantial economic losses. Although traditional vaccines have helped reduce the disease burden, they typically rely on multivalent antigens, emphasize humoral immunity, and require intensive production. This study aimed to establish a genetically matched host–cell system to evaluate antigen-specific immune responses and identify conserved CD8+ T cell epitopes in avian influenza viruses. To this end, we developed an MHC class I genotype (B21)-matched host (Lohmann VALO SPF chicken) and cell vector (DF-1 cell line) model. DF-1 cells were engineered to express the hemagglutinin (HA) gene of clade 2.3.4.4b H5N1 either transiently or stably, and to stably express the matrix 1 (M1) and nucleoprotein (NP) genes of A/chicken/South Korea/SL20/2020 (H9N2, Y280-lineage). Following prime-boost immunization with HA-expressing DF-1 cells, only live cells induced strong hemagglutination inhibition (HI) and virus-neutralizing (VN) antibody titers in haplotype-matched chickens. Importantly, immunization with DF-1 cells transiently expressing NP induced stronger IFN-γ production than those expressing M1, demonstrating the platform’s potential for differentiating antigen-specific cellular responses. CD8+ T cell epitope mapping by mass spectrometry identified one distinct MHC class I-bound peptide from each of the HA-, M1-, and NP-expressing DF-1 cell lines. Notably, the identified HA epitope was conserved in 97.6% of H5-subtype IAVs, and the NP epitope in 98.5% of pan-subtype IAVs. These findings highlight the platform’s utility for antigen dissection and rational vaccine design. While limited by MHC compatibility, this approach enables identification of naturally presented epitopes and provides insight into conserved, functionally constrained viral targets. Full article