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Background: Because patients infected with respiratory syncytial virus (RSV) have been reported to be older than patients infected with influenza virus, the more frequent incidence of complications in RSV-infected patients may be age-related. This study compared clinical characteristics and outcomes in hospitalized adults infected with RSV with findings in age- and sex-matched adults infected with influenza virus., Methods: The medical records of hospitalized adult patients infected with RSV or influenza virus at two university hospitals from 2013 to 2022 were retrospectively analyzed. Virus infection was confirmed by real-time polymerase chain reaction. Each RSV-infected patient was matched by age and sex with two influenza virus-infected patients, and their clinical symptoms, laboratory parameters and hospital courses were compared., Results: The study cohort consisted of 552 patients, 184 infected with RSV and 368 infected with influenza virus. Fever (71.2% vs. 79.9%, p  = .022) and cough (70.1% vs. 80.4%, p  = .007) were significantly less frequent in the RSV than in the influenza group, whereas white blood cell counts (9132/mm 3 vs. 7616/mm 3 , p  < .001) and C-reactive protein concentrations (10.25 vs. 8.88 mg/dL, p  = .029) were significantly higher in the RSV group. The frequency of oxygen therapy was higher (60.3% vs. 48.6%, p  = .010) and hospital stay was longer (8 vs. 6 days, p  = .003) in RSV than in influenza virus-infected patients., Conclusions: Clinical symptoms were less frequent, but disease was more severe, in hospitalized adult patients infected with RSV than in age- and sex-matched patients infected with influenza. Greater attention should be paid to diagnosing and preventing RSV infection in adults.

Aim: Backyard production systems (BPS) represent an interface of contact between people, domestic and wild animals. Studies conducted in Chile during the last decade have provided extensive evidence of influenza A virus (IAV) circulation in backyard poultry and swine. The aim of this study was to investigate exposure practices of humans to animal-origin IAV within backyards., Methods and Results: Backyard farmers and household members of a total of 101 BPS in the proximity of wetlands located throughout Chile were interviewed between 2021 and 2022. Data were collected on the nature of human-animal contacts through participation in productive activities conducted within backyards, which was used to estimate participants' exposure risk to animal-origin IAV. Additionally, RT-qPCR and serologic IAV active surveillance was carried out in backyard animals. Multilinear regression was used to identify factors associated with exposure risk. Overall, IAV prevalence was 10.1% (95% CI: 4.7%-15.5%) and seroprevalence was 43.5% (95% CI: 29.7%-54.2%), both at the BPS level. Of 180 interviewees, 86% reported participating regularly in poultry or swine exposure activities within the backyard. A greater participation of male participants was observed when evaluating swine exposure activities, while female participation was greater for some activities related to poultry handling. Handwashing was a very extended hygiene practice; however, the use of personal protective equipment was uncommon. Different factors related to participants, households and backyards were associated with an increased exposure risk of participants to animal-origin IAV: (i) older age, (ii) less years of education, (iii) no off-farm work, (iv) greater backyard production value and (v) greater household consumption of backyard products., Conclusion: These results indicate the circulation of IAV in BPS and the frequent human-animal contact at this interface, highlighting the need for awareness campaigns and educational programmes aimed at backyard farmers on prevention and biosecurity measures in the management of backyard animals., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Background: To evaluate the influenza-like illness (ILI) and acute respiratory infection (ARI) case definitions in the diagnosis of COVID-19 and influenza in healthcare personnel (HCP)., Methods: We followed a cohort of 5752 HCP from November 2022 to May 2023. Symptomatic HCP were tested for SARS-CoV-2 and influenza by real-time PCR and/or rapid antigen detection test. ILI was defined as the sudden onset of ≥1 systemic symptom and ≥1 respiratory symptom. ARI was defined as the sudden onset of ≥1 respiratory symptom. Patients with respiratory symptoms were grouped either as ILI or as ARI based on the presence of fever, malaise, headache and/or myalgia., Results: Overall, 466 ILI cases and 383 ARI cases occurred. HCP with ILI had an adjusted odds ratio (aOR) of 22.05 [95% confidence interval (CI): 6.23-78.04] to be diagnosed with influenza. HCP with ARI had an aOR of 2.70 (95% CI: 1.88-3.88) to be diagnosed with COVID-19. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of ILI for influenza were 96.6%, 49.9%, 18.2%, and 99.2%, respectively. The sensitivity, specificity, PPV, and NPV of ARI for COVID-19 were 51.7%, 73.6%, 84.9%, and 34.8%, respectively. ILI and ARI had an overall correct classification rate of 89.6% and 74.1%, respectively., Conclusion: Our findings support the use of both ILI and ARI case definitions in the diagnosis of influenza and COVID-19 in HCP., Competing Interests: Declaration of competing interest Dr Maltezou received an honorarium from Novavax to participate in a symposium. The authors have no conflict of interest to declare., (Copyright © 2024 Australasian College for Infection Prevention and Control. Published by Elsevier B.V. All rights reserved.)

Objectives: To evaluate the efficacy and safety of ZX-7101A: an inhibitor of influenza viral cap-dependent endonuclease, in adults with uncomplicated influenza and explore treatment-emergent resistance., Methods: We conducted a randomized, double-blind, placebo-controlled, adaptive-design phase 2 and phase 3 studies (ZX-7101A-202) in adults with uncomplicated influenza. Eligible patients were randomized 1:1:1 to receive a single dose of 40 or 80 mg ZX-7101A or placebo, stratified by body weight and baseline composite symptom score. The primary efficacy endpoint was time to alleviation of influenza symptoms (TTAS) in intention-to-treat infected population., Results: The phase 2 trial suggested significantly shorter TTAS for ZX-7101A compared with placebo: the median TTAS of 40 or 80 mg ZX-7101A groups were 34.7 hours (95% CI, 22.8-43.4; p 0.005) and 45.8 hours (95% CI, 32.0-66.3; p 0.020), compared with 63.6 hours (95% CI, 43.9-93.4) in the placebo group. In the phase 3 trial, the TTAS of both ZX-7101A dose groups was significantly shortened relative to the that of placebo group: the median TTAS was shortened to 48.4 hours (95% CI, 40.5-55.6) for 40 mg group and 39.4 hours (95% CI, 35.8-49.3) for 80 mg group, compared with 62.9 hours (95% CI, 56.4-69.3) for placebo group (p 0.003 and p < 0.001, respectively). In the safety population, ZX-7101A treatment was associated with fewer adverse events, with 41.8% (100/239) in the 40 mg group, 44.2% (106/240) in the 80 mg group, and 53.8% (129/240) in the placebo group. The majority of adverse events were mild or moderate. Emergence of resistance to ZX-7101A through I38T amino acid substitution was detected in 5/278 (1.8%) patients., Discussion: ZX-7101A was an effective treatment for influenza with a single dose of either 40 mg or 80 mg, with more rapid alleviation of influenza symptoms vs. placebo. No safety concerns were identified with single dose treatment of ZX-7101A., (Copyright © 2024 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Studies have indicated the potential importance of the human nasal and respiratory microbiomes in health and disease. However, the roles of these microbiomes in the pathogenesis of influenza and its complications are not fully understood. Therefore, the objective of this systematic review and analysis is to identify the patterns of nasal and respiratory microbiome dysbiosis and to define the unique signature bacteria associated with influenza compared with other respiratory tract infections. We compared the respiratory microbiome composition between influenza patients and healthy controls; across different influenza severities; in adult versus pediatric influenza patients; as well as influenza versus other respiratory infections. The desired outcomes include the signature bacteria in each cohort and the Shannon index to reflect the alpha diversity. Of the 2269 articles identified, 31 studies fulfilled the inclusion criteria. These studies investigated the respiratory tract microbiomes of patients with influenza, COVID-19, pneumonia, other respiratory infections, and chronic rhinosinusitis (CRS). Our review revealed that the phylum Firmicutes and Actinobacteria , genus Actinomyces , Streptococcus and Granulicatella , and species Neisseria are more prominent in severe influenza than mild to moderate influenza. Reduced microbiome alpha diversity is noted in influenza patients compared to healthy controls. There are some similarities and differences between the signature bacteria in pediatric and adult influenza patients, e.g., Streptococcus is common in both age groups, whereas Pseudomonas is associated with adults. Intriguingly, there is a common predominance of Streptococcus and Firmicutes among influenza and pneumonia patients. COVID-19 patients exhibit an increased abundance of Firmicutes as well as Pseudomonas . In CRS patients, Proteobacteria and Haemophilus are found in high abundance. This review highlights some similarities and differences in the respiratory microbiomes and their signature organisms in influenza of varying severity and in different age groups compared with other respiratory infections. The dysbiosis of the respiratory microbiomes in these respiratory infections enhances our understanding of their underlying pathogenic mechanisms.

Background: Influenza virus is a contagious respiratory pathogen that can cause severe acute infections with long-term adverse outcomes. For paediatric patients at high risk of severe influenza, the readmission and the associated risk factors remain unclear., Methods: Children discharged with a diagnosis of severe or critical influenza from October 2021 to March 2022 were included. The disease severity was categorized according to the "2020 edition of the Chinese expert consensus on the diagnosis and treatment of influenza in children". Demographic data, clinical characteristics, underlying medical conditions, microbiology, treatment outcomes, and 90-day readmissions were retrieved and retrospectively analyzed. Those who tested positive for COVID-19 were excluded. Risk factors independently associated with readmission were identified using multiple logistic regression models., Results: During the study period, 225 children with severe influenza were hospitalized and 14.7% (33/225) of them were readmitted within 90 days. The median length of readmission was 62 (IQR, 31-76) days, and the most common cause of readmission was pneumonia. M. pneumoniae and influenza virus are the most common infections for readmission The children who were readmitted were more likely to have critical influenza and neurological comorbidities compared to patients without readmission. The readmitted children had a significantly higher proportion of natural killer cells and a shorter febrile duration and length of stay on their first admission, compared with those who were not readmitted. Rhinosinusitis (OR = 30.085, p = .008) and high level of natural killer cells (OR = 1.107, p = .012) were independent risk factors and febrile duration (OR, 0.748, p = .018) was a protective factor for 90-day readmission., Conclusions: Our findings suggest that, to reduce the potential readmission of children with severe influenza, a sustained focus on the risk factors including rhinosinusitis and over-activated host immune response during the index hospitalization is needed., Competing Interests: Declarations. Ethics approval and consent to participate: This study was approved by the Clinical Research Ethics Committee of the Children’s Hospital of Hebei (CHH) in accordance with the principles of the Declaration of Helsinki and the Code of Ethics of the World Medical Association. As the data in this collected from inpatient electronic medical records, there was no need to collect new specimens, and all patients were de-identified, so the informed consent was waived by Clinical Research Ethics Committee of CHH. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Wild birds are one of the main natural reservoirs for avian influenza viruses, and their migratory behavior significantly influences the transmission of avian influenza. To better describe the migratory behavior of wild birds, a system of reaction-advection-diffusion equations is developed to characterize the interactions among wild birds, poultry, and humans. By the next-generation operator, the basic reproduction number of the model is formulated. Then the threshold dynamic of the model is explored by some techniques including the theory of uniform persistence, internally chain transitive sets, and so on. Subsequently, the sensitivity analysis of parameters associated with the basic reproduction number is implemented. According to the temporal and spatial overlapping relationship between wild blue-winged ducks and poultry in North America, the effect of this relationship on the characteristic of spatial-temporal distribution of the viruses is well studied. Additionally, the risk of virus transmission from wild birds to poultry and humans is evaluated. The main results highlight that the basic reproduction number is more significantly affected by the parameters related to wild birds. Interestingly, the model output regarding the spatial distribution of poultry infections is consistent with the actual findings. Moreover, the risk of virus spillover from wild birds into poultry and humans varies with wild bird behavior and has a more substantial impact on poultry. Throughout this study, the critical risk points in the transmission process are identified, providing a theoretical basis for the prevention and control of avian influenza., Competing Interests: Declarations. Conflict of interest: Both authors declare that there is no conflict of interest in this study., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Influenza A viruses (IAVs) are highly contagious pathogens that cause zoonotic disease with limited availability of antiviral therapies, presenting ongoing challenges to both public health and the livestock industry. Unveiling host proteins that are crucial to the IAV life cycle can help clarify mechanisms of viral replication and identify potential targets for developing alternative host-directed therapies. Using a four-dimensional (4D), label-free methodology coupled with bioinformatics analysis, we analyzed the expression patterns of cellular proteins that changed following H9N2 virus infection. Compared to the control group, the H9N2 infected group displayed 732 differentially expressed proteins (DEPs), with 298 proteins showing upregulation and 434 proteins showing downregulation. Gene Ontology (GO) functional analysis showed that DEPs were catalog in 11 biological processes, three cellular components, and eight molecular functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that DEPs were involved in processes including cytokine signaling pathways induced by virus infection and protein digestion and absorption. Proteins including TP53, DDX58, and STAT3 were among the top hub proteins in the protein-protein interaction (PPI) analysis, suggesting that these signaling cascades could be essential for the propagation of IAVs. Furthermore, the host protein SNAPIN was chosen to ascertain the accuracy of expression changes identified through a proteomic analysis. The results indicated that SNAPIN was downregulated following infection with IAVs both in vitro and in vivo, which is consistent with the proteomics results, suggesting that SNAPIN may serve as a key regulatory factor in the viral life cycle of IAVs. Our research delineates an extensive interaction map of IAV infection within the A549 cells, facilitating the discovery of pivotal proteins that contribute to the virus's propagation, potentially offering target candidates to screen for antiviral therapeutics.

Galectins are β-galactosyl-binding lectins with key roles in early development, immune regulation, and infectious disease. Influenza A virus (IAV) infects the airway epithelia, and in severe cases may lead to bacterial superinfections and hypercytokinemia, and eventually, to acute respiratory distress syndrome (ARDS) through the breakdown of airway barriers. The detailed mechanisms involved, however, remain poorly understood. Our prior in vivo studies in a murine model system revealed that upon experimental IAV and pneumococcal primary and secondary challenges, respectively, galectin-1 and galectin-3 (Gal-3) are released into the airway and bind to the epithelium that has been desialylated by the viral neuraminidase, contributing to secondary bacterial infection and hypercytokinemia leading to the clinical decline and death of the animals. Here we report the results of in vitro studies that reveal the role of the extracellular Gal-3 in additional detrimental effects on the host by disrupting the integrity of the airway epithelial barrier. IAV infection of the human airway epithelia cell line A549 increased release of Gal-3 and its binding to the A549 desialylated cell surface, notably to the transmembrane signaling receptors CD147 and integrin-β1. Addition of recombinant Gal-3 to A549 monolayers resulted in enhanced expression and release of matrix metalloproteinases, leading to disruption of cell-cell tight junctions, and a significant increase in paracellular permeability. This study reveals a critical mechanism involving Gal-3 that may significantly contribute to the severity of IAV infections by promoting disruption of tight junctions and enhanced permeability of the airway epithelia, potentially leading to lung edema and ARDS., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Influenza remains a persistent global health challenge, largely due to the virus' continuous antigenic drift and occasional shift, which impede the development of a universal vaccine. To address this, the identification of broadly neutralizing antibodies and their epitopes is crucial. Nanobodies, with their unique characteristics and binding capacity, offer a promising avenue to identify such epitopes. Here, we isolate and purify a hemagglutinin (HA)-specific nanobody that recognizes an H7 subtype of influenza A virus. The nanobody, named E10, exhibits broad-spectrum binding, cross-group neutralization and in vivo protection across various influenza A subtypes. Through phage display and in vitro characterization, we demonstrate that E10 specifically targets an epitope on HA head which is part of the conserved lateral patch and is highly immunodominant upon H7 infection. Importantly, immunization with a peptide including the E10 epitope elicits cross-reactive antibodies and mediates partial protection from lethal viral challenge. Our data highlights the potential of E10 and its associated epitope as a candidate for future influenza prevention strategies., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Despite extensive experience with influenza surveillance in humans in Senegal, there is limited knowledge about the actual situation and genetic diversity of avian influenza viruses (AIVs) circulating in the country, hindering control measures and pandemic risk assessment. Therefore, as part of the "One Health" approach to influenza surveillance, we conducted active AIV surveillance in two live bird markets (LBMs) in Dakar to better understand the dynamics and diversity of influenza viruses in Senegal, obtain genetic profiles of circulating AIVs, and assess the risk of emergence of novel strains and their transmission to humans. Cloacal swabs from poultry and environmental samples collected weekly from the two LBMs were screened by RT-qPCR for H5, H7, and H9 AIVs. Subsequently, a subset of H9-positive samples was selected for whole sequencing. From December 2023 to October 2024, 499 samples were tested, and AIV was detected in 58.3% of them. Among these, A/H9N2 was the only subtype detected in both markets, with a detection rate of 47.7% (82/172) in Thiaroye and 35.3% (42/119) in Tilene, resulting in an overall positivity rate of 42.6% (124/291). Genome sequencing of 22 A/H9N2 isolates, including 11 poultry drinking water samples, 7 carcass wash water samples, 3 fecal samples, and 1 cloacal swab, yielded 7 complete and 15 partial genomic sequences. Phylogenetic analyses of the resulting sequences showed that the A/H9N2 isolates obtained in this study formed a monophyletic cluster and were closely related to the Senegalese human strain (A/Senegal/0243/2019) identified through the national influenza sentinel surveillance program. These strains were also closely related to the A/H9N2 viruses of the G1 lineage circulating in neighboring countries, suggesting cross-border transmission. The A/H9N2 strains carried the low pathogenicity RSSR/GLF motif at the HA cleavage site and possessed several key amino acid mutations, including HA-I155T and HA-Q226L, which are associated with human host adaptation, PB2-T105V, PB2-A661T, and PB2-A588V, which are linked to the human-to-human transmission and increased polymerase activity, NS2-T14M, NS2-M100I, NS1-I106M, NS1-V222M, NS1-E223A, NS1-I226V, NS1-E227G, and NS1-P228S, which are known to alter virulence (increased or reduced) in humans or mice, and M2-S31N, which promotes drug resistance. Seven potential N-glycosylation sites were predicted in the HA protein and six in the NA protein. The selection pressure analysis revealed that the A/H9N2 isolates were primarily under neutral evolution or purifying selection pressure. Overall, our findings highlight the potential for cross-species transmission of Senegalese A/H9N2 viruses, emphasizing the need for sustained monitoring of these viruses in both animal and human populations.

Background: The morbidity and mortality associated with influenza viruses are a significant public health challenge. Annual vaccination against circulating influenza strains reduces hospitalisations and increases survival rates but requires a yearly redesign of vaccines against prevalent subtypes. The complex genetics of influenza viruses with high antigenic drift create an ongoing challenge in vaccine development to address dynamic influenza epidemiology. Understanding the evolution of influenza viruses and the vaccine's effectiveness against different types and subtypes is pivotal to designing public health measures against influenza., Methods: We conducted a systematic review and meta-analysis of 192 705 patients, collecting information on the incidence and severity of the disease. The results of this meta-analysis were further validated using data from 6 594 765 patients from TriNetX. We analysed the prevalence of the most common influenza A virus (IAV) subtypes (H1N1 and H3N2) and influenza B virus (IBV), as well as vaccination effectiveness against them in three age groups, given that age is associated with influenza disease severity., Results: Our analysis reflects that overall vaccination against H1N1 IAV and IBV is effective in reducing infection and influenza-related complications in children aged <5 years old, individuals between 5 and 65 years old and older adults aged >65 years old. By contrast, while vaccination against H3N2 IAV is effective in protecting against infection in infants <5 years old, it provides reduced protection against infection in older individuals., Conclusions: Despite higher infection rates, vaccination against H3N2 remains as highly effective as vaccination against H1N1 and IBV in reducing influenza-related morbidity and mortality in all age groups. Detailing vaccine effectiveness in terms of infection protection and disease burden across different age groups is necessary for understanding vaccine impacts in terms of other outcomes, e.g. hospitalisations, mortality and disease severity; for improving vaccine formulations and public awareness; and for enhancing vaccination campaigns to improve coverage and public acceptance., Competing Interests: Conflict of interest: All authors have nothing to disclose., (Copyright ©The authors 2025.)

Long non-coding RNAs (lncRNAs) are essential components of innate immunity, maintaining the functionality of immune systems that control virus infection. However, how lncRNAs engage immune responses during influenza A virus (IAV) infection remains unclear. Here, we show that lncRNA USP30-AS1 is up-regulated by infection of multiple different IAV subtypes and is required for tuning inflammatory and antiviral response in IAV infection. Genetically inactivation of USP30-AS1 enhances viral protein synthesis and viral growth. USP30-AS1 is an interferon-stimulated gene, and the induction of USP30-AS1 can be achieved by JAK-STAT mediated signaling activation. The immune regulation of USP30-AS1 is independent of its proximal protein-coding gene USP30. In IAV infection, deletion of USP30-AS1 unleashes high systemic inflammatory responses involving a broad range of pro-inflammatory factors, suggesting USP30-AS1 as a critical modulator of immune responses in IAV infection. Furthermore, we established a database providing well-annotated host gene expression profiles IAV infection or immune stimulation., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Cao et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Identifying broadly reactive B precursor cells and conserved epitopes is crucial for developing a universal flu vaccine. In this study, using influenza neuraminidase (NA) mutant probes, we find that human pre-existing NA-specific memory B cells (MBCs) account for ∼0.25% of total MBCs, which are heterogeneous and dominated by class-unswitched MBCs. In addition, we identify three NA broad-inhibition monoclonal antibodies (mAbs) (BImAbs) that block the activity of NA derived from different influenza strains, including the recent cow H5N1. The cryoelectron microscopy (cryo-EM) structure shows that the BImAb targets the conserved NA enzymatic pocket and a separate epitope in the neighboring NA monomer. Furthermore, the NA BImAbs protect mice from the lethal challenge of the human pandemic H1N1 and H5N1. Our work demonstrates that the NA broad-inhibition precursor MBCs exist in healthy adults and could be targeted by the NA-based universal flu vaccine., Competing Interests: Declaration of interests Westlake University has filed for patent protection for NA antibodies discovered in this study., (Copyright © 2024 Elsevier Inc. All rights reserved.)

East, South, and Southeast Asia (together referred to as Southeastern Asia hereafter) have been recognized as critical areas fuelling the global circulation of seasonal influenza. However, the seasonal influenza migration network within Southeastern Asia remains unclear, including how pandemic-related disruptions altered this network. We leveraged genetic, epidemiological, and airline travel data between 2007-2023 to characterise the dispersal patterns of influenza A/H3N2 and B/Victoria viruses both out of and within Southeastern Asia, including during perturbations by the 2009 A/H1N1 and COVID-19 pandemics. During the COVID-19 pandemic, consistent autumn-winter movement waves from Southeastern Asia to temperate regions were interrupted for both subtype/lineages, however the A/H1N1 pandemic only disrupted A/H3N2 spread. We find a higher persistence of A/H3N2 than B/Victoria circulation in Southeastern Asia and identify distinct pandemic-related disruptions in A/H3N2 antigenic evolution between two pandemics, compared to interpandemic levels; similar patterns are observed in B/Victoria using genetic distance. The internal movement structure within Southeastern Asia markedly diverged during the COVID-19 pandemic season, and to a lesser extent, during the 2009 A/H1N1 pandemic season. Our findings provide insights into the heterogeneous impact of two distinct pandemic-related disruptions on influenza circulation, which can help anticipate the effects of future pandemics and potential mitigation strategies on influenza dynamics., Competing Interests: Competing interests: H.Y. received research funding from Sanofi Pasteur, GlaxoSmithKline, Yichang HEC Changjiang, Shanghai Roche Pharmaceutical Company, and SINOVAC Biotech Ltd. None of these funds are related to this work. All other authors declare no competing interests., (© 2025. The Author(s).)

Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) is one of hundreds of host-cell factors involved in the propagation of type A influenza virus (IAV), although its mechanism of action is unknown. Here, we identified CaMKII inhibitory peptide M3 by targeting its kinase domain using affinity-based screening of a tailored random peptide library. M3 inhibited IAV cytopathicity and propagation in cells by specifically inhibiting the acute-phase activation of retinoic acid-inducible gene I (RIG-I), which is uniquely regulated by CaMKII. Downstream of the RIG-I pathway activated TBK1 and then IRF3, which induced small but sufficient amounts of transcripts of the genes for IFN α/β to provide the capped 5'-ends that were used preferentially as primers to synthesize viral mRNAs by the cap-snatching mechanism. Importantly, knockout of RIG-I in cells almost completely inhibited the expression of IFN mRNAs and subsequent viral NP mRNA early in infection (up to 6 h after infection), which then protected cells from cytopathicity 24 h after infection. Thus, CaMKII-dependent acute-phase activation of RIG-I promoted IAV propagation, whereas the canonical RIG-I pathway stimulated antiviral activity by inducing large amounts of mRNA for IFNs and then for antiviral proteins later in infection. Co-administration of M3 with IAV infection rescued mice from the lethality and greatly reduced proinflammatory cytokine mRNA expression in the lung, indicating that M3 is highly effective against IAV in vivo . Thus, regulation of the CaMKII-dependent non-canonical RIG-I pathway may provide a novel host-factor-directed antiviral therapy.IMPORTANCEThe recent emergence of IAV strains resistant to commonly used therapeutic agents that target viral proteins has exacerbated the need for innovative strategies. Here, we originally identified CaMKII-inhibitory peptide M3, which efficiently inhibits IAV-lethality in vitro and in vivo . M3 specifically inhibited the acute-phase activation of RIG-I, which is a novel pathway to promote IAV propagation. Thus, this pathway acts in an opposite manner compared with the canonical RIG-I pathway, which plays essential roles in antiviral innate immune response later in infection. The CaMKII-dependent non-canonical RIG-I pathway can be a promising and novel drug target for the treatment of infections., Competing Interests: The authors declare no conflict of interest.

Lack of Herpes Simplex Virus (HSV) vaccine, low vaccination rates of Influenza viruses, waning immunity and viral transmission after vaccination underscore the need to reduce viral loads at their transmission sites. Oral virus transmission is several orders of magnitude higher than nasal transmission. Therefore, in this study, we evaluated neutralization of viruses using a natural viral trap protein (FRIL) formulated in clinical-grade chewing gum. FRIL is highly stable in the lablab bean powder (683 days) and in chewing gum (790 days), and fully functional (794 days) when stored at ambient temperature. They passed the bioburden test with no aerobic bacteria, yeasts/molds, with minimal moisture content (1.28-5.9%). Bean gum extracts trapped HSV-1/HSV-2 75-94% in a dose-dependent manner through virus self-aggregation. Mastication simulator released >50% release of FRIL within 15 min of chewing the bean gum. In plaque reduction assays, >95% neutralization of H1N1 and H3N2 required ∼40 mg/mL, HSV-1 160 mg/mL, and HSV-2 74 mg/mL of bean gum for 1,000 copies/mL virus particles. Therefore, a 2000 mg bean gum tablet has more than adequate potency for clinical evaluation and is safe with no detectable levels of glycosides. These observations augur well for evaluating bean gum in human clinical studies to minimize virus infection/transmission., Competing Interests: Declaration of interests HD is a patentee in plant-based oral and topical drug delivery and was previously funded by Novo Nordisk, Bayer, Shire and Takeda. Several industry discussions for advancing clinical trials in oral or topical delivery are in progress. Complete list of patents is available in the Google Scholar or ScholarGPS links below: http://scholar.google (in PBS buffer).com/citations?user = 7sow4jwAAAAJ&hl = en https://scholargps.com/scholars/82094026790000/henry-daniell., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

TMPRSS2, a human transmembrane protease enzyme, plays a crucial role in the spread of certain viruses, including influenza and coronaviruses. This enzyme promotes viral infection by cleaving viral glycoproteins, which helps viruses like SARS-CoV-2 and influenza A enter cells more effectively. Genetic differences in TMPRSS2 may affect people's susceptibility to COVID-19, underscoring the need for studies that consider diverse populations. Beyond infectious diseases, TMPRSS2 has also been linked to some cancers, suggesting it could be a valuable target for drug development. This review provides a summary of TMPRSS2 inhibitors currently under study, with some already in clinical trials to test their effectiveness against viral infections. As we uncover more about TMPRSS2's role in pathogenesis, it could open new doors for therapies to combat future outbreaks.

The discovery of long non-coding RNAs (lncRNAs) has provided a new perspective on the centrality of RNA in gene regulation and genome organization. Here, we screened for lncRNAs with putative functions in the host response to single-stranded RNA respiratory viruses. We identify CARINH as a conserved cis-acting lncRNA up-regulated in three respiratory diseases to control the expression of its antisense gene IRF1 , a key transcriptional regulator of the antiviral response. CARINH and IRF1 are coordinately increased in the circulation of patients infected with human metapneumovirus, influenza A virus, or SARS-CoV-2, and in macrophages in response to viral infection or TLR3 agonist treatment. Targeted depletion of CARINH or its mouse ortholog Carinh in macrophages reduces the expression of IRF1/Irf1 and their associated target gene networks, increasing susceptibility to viral infection. Accordingly, CRISPR-mediated deletion of Carinh in mice reduces antiviral immunity, increasing viral burden upon sublethal challenge with influenza A virus. Together, these findings identify a conserved role of lncRNA CARINH in coordinating interferon-stimulated genes and antiviral immune responses., (© 2025 Cyr et al.)

Crocodilians are susceptible to a range of virus infection including influenza A virus (IAV). However, little is known about the ecology and epidemiology of IAV in crocodile species. This study aimed to investigate IAV infection in farmed Siamese crocodiles in central Thailand. We collected plasma samples and pharyngeal swab samples from Siamese crocodiles residing in 13 crocodile farms in 9 provinces of central Thailand during 2019. Additional archival plasma samples of Siamese crocodiles collected in 2012 and 2018 were also included in the study. Plasma samples were screened for influenza A antibodies by a hemagglutination inhibition (HI) assay and positive were evaluated by a cytopathic effect/hemagglutination based-microneutralization (MN) assay. Swab samples were tested for influenza viral RNA by a real-time RT-PCR assay targeting the influenza matrix (M) gene. Among 246 tested plasma samples, the overall seroprevalence of antibodies against IAV in farmed Siamese crocodiles was 17.5% (43/246). The most common hemagglutinin (HA) subtype was H2 (46.5%, 20/43) followed by H9 (39.5%, 17/43), human H1 (14%, 6/43) and H1 (7%, 3/43). Multiple HA subtypes were also detected in 7% (3/43) of infected crocodiles with combination of H1 and H2 subtypes. All 126 tested swab samples were negative for influenza viral RNA. In addition, we demonstrated the ability of wild-type IAV subtypes (H1, H2, H9 and human H1) to infect primary Siamese crocodile fibroblast cells. To our knowledge, this is the first report of serological evidences of avian and human IAV infection in Siamese crocodiles. Our findings highlighted the role of crocodile species in the ecology of IAV particularly the potential to serve as the reservoir or mixing vessel for the viruses that significantly threaten both human and animal health., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2025 Thongdee et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Human bocavirus-1 (HBoV-1) has been associated with respiratory infections in both children and adults, often presenting symptoms similar to those of influenza. Understanding the prevalence and molecular characteristics of HBoV-1 in individuals with influenza-like illness (ILI) is essential for enhancing the diagnosis and treatment of respiratory infections in Kunming, Southwest China. Between December 2017 and December 2023, demographic and clinical data, along with respiratory tract specimens from individuals aged 0 to 97 years with ILI, were collected at three sentinel hospitals in Kunming. Each specimen was tested for 18 respiratory viruses, and the positive rates of HBoV-1 across different age groups were analyzed. Amplification of the near-complete HBoV genome was achieved through three overlapping fragments, followed by next-generation sequencing (NGS) and phylogenetic analysis. A total of 20,181 respiratory samples were collected from patients aged 1 month to 97 years presenting with ILI symptoms between December 2017 and December 2023, with HBoV detected in 0.8% of the samples. The prevalence was 1.0% (165/16,406) in children and 0.1% (3/3,775) in adults, with a significantly higher detection rate in pediatric patients (<18 years old) compared to adults (≥18 years old) ( P < 0.001). Among the 168 HBoV-positive participants, 165 (98.2%) were children under 18 years, while 3 (1.8%) were adults. Genome-wide phylogenetic analyses indicated that HBoV-1 was the predominant genotype, showing that the HBoV-1 strains circulating in Kunming are closely related to strains from other regions of China and globally. Our findings confirm the prevalence of HBoV-1 in individuals with ILI in Kunming and provide valuable insights into the molecular characteristics of HBoV-1 in this region. Further studies are necessary to explore the clinical implications of HBoV-1 infection and its role in respiratory illnesses.IMPORTANCEViral respiratory infections are a leading cause of morbidity- and mortality-associated influenza-like illness (ILI) cases. It is estimated that there are several billion cases of ILI globally each year. Monitoring data from China in 2023 indicate that there are approximately 17 million cases of ILI nationwide. In the United States, the annual incidence of ILI ranges from 9 to 49 million cases. Human bocavirus-1 (HBoV-1) has been identified as a causative agent of ILI. The global prevalence of HBoV-1 respiratory infections varies from 1% to 56.8%, with the majority of studies focusing on pediatric populations; however, research including a broader age range is limited. Currently, the prevalence of HBoV-1 in the Kunming area is not well characterized, and its molecular features remain inadequately described. This study aims to analyze the prevalence of HBoV-1 among ILI cases in Kunming, encompassing both pediatric and adult patients. We present 107 complete genomic sequences of HBoV-1 strains obtained from three ILI sentinel hospitals in the region. Furthermore, we conducted phylogenetic analysis, homology comparisons, and assessments of nucleotide and amino acid substitution site variations. These findings provide important insights for further investigations into HBoV-1 and its epidemiological significance., Competing Interests: The authors declare no conflict of interest.

The I38T substitution in the influenza virus polymerase-acidic (PA) subunit is a resistance marker of concern for treatment with the antiviral baloxavir marboxil (BXM). Thus, monitoring PA/I38T mutations is of clinical importance. Here, we developed three rapid and sensitive assays for the detection and monitoring of the PA/I38T mutation. In addition, we updated our previously developed methods to monitor the D197N mutation in the neuraminidase (NA) of influenza B virus, which is associated with resistance to oseltamivir. Real-time PCR high-resolution melting analysis (HRMA) was developed for the rapid detection of the PA/I38T and NA/D197N mutations using oligonucleotides with substitutions of interest and influenza viruses isolated in our laboratory. HRMA was subsequently performed on 94 clinical samples that were positive for A/H1N1pdm09, A/H3N2, and type-B influenza viruses and on viruses that were selected in vitro to grow in the presence of BXA (baloxavir acid, BXM active compound). The HRMAs were able to discriminate PA/I38 from the PA/I38T mutation and NA substitutions in synthetic oligonucleotides. However, the I38T mutation and NA mutations were not detected in any of our clinical samples, indicating the absence of these resistance markers in the circulating viruses examined. Only one out of 43 A/H3N2 clinical samples analyzed contained a virus with mutations associated with resistance to oseltamivir. All the HRMA results were confirmed by sequencing. Finally, HRMA was performed on A/H1N1pdm09 and A/H3N2 influenza viruses following BXA selection in vitro. The presence of the I38T mutation in the BXA-selected A/H3N2 variant, but not in the A/H1N1pdm09 variant, was identified by HRMA after 12 passages. Overall, these findings indicate that HRMA could be a powerful tool for rapidly monitoring BXM resistance in influenza viruses during seasonal circulation., Competing Interests: Declarations. Conflict of interest: The authors declare that they have no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The seasonality and epidemiology of viral acute respiratory infections (ARIs) have changed since the coronavirus disease 2019 pandemic. However, molecular-based ARI surveillance has not been conducted in Japan. We developed a regional surveillance program to define the local epidemiology of ARIs. Between December 2023 and March 2024, 2,992 upper respiratory samples collected from patients suspected of having ARIs at five facilities in Kyoto City, Japan, were tested for SARS-CoV-2, influenza virus, and respiratory syncytial virus (RSV) using RT‒PCR. Samples negative for these viruses were randomly selected for testing with the FilmArray Respiratory Panel, and the detection rates of other viruses were estimated. SARS-CoV-2, influenza virus, and RSV were detected in 598 (20.3%), 165 (5.6%), and 40 (1.4%) of the 2,949 samples with valid RT‒PCR results, respectively. The most prevalent viruses in the < 6, 6-17, 18-64, and ≥ 65 year age groups were rhinovirus/enterovirus, RSV, and SARS-CoV-2; influenza virus, seasonal coronavirus, and rhinovirus/enterovirus; SARS-CoV-2, seasonal coronavirus, and influenza virus; and SARS-CoV-2, seasonal coronavirus, and influenza virus, respectively. Significant differences in the detection rates of these viruses were detected between the age groups. This study highlights the importance of age-stratified molecular-based surveillance for a comprehensive understanding of the epidemiology of ARIs., Competing Interests: Declarations. Competing interests: YM received research funds from Beckman Coulter, Precision System Science, and Toyobo. MN received research funds from Beckman Coulter and Precision System Science. MY, Y.Tsuda, KS, Y.Tsuchido, SY, TN, and KT declare no potential conflict of interest. Ethical approval: This study was performed in accordance with the principles of the Declaration of Helsinki. The Ethics Committee of Kyoto University Graduate School and the Faculty of Medicine approved this study (R4195), and the need to obtain informed consent from each patient was waived., (© 2025. The Author(s).)

To battle seasonal outbreaks of influenza B virus infection, which continue to pose a major threat to world health, new and improved vaccines are urgently needed. In this article, we discuss the current state of next-generation influenza B vaccine development, including both advancements and challenges. This review covers the shortcomings of existing influenza vaccines and stresses the need for more-effective and broadly protective vaccines and more-easily scalable manufacturing processes. New possibilities for vaccine development have emerged due to recent technical developments such as virus-like particle (VLP) platforms, recombinant DNA technologies, and reverse genetics. By using these methods, vaccines can be developed that elicit stronger and longer-lasting immune responses against various strains of influenza B virus. Vaccines may be more effective and immunogenic when adjuvants and new delivery mechanisms are used. Progress has been made in the development of influenza B vaccine mRNA vaccines, nanoparticle-based vaccines, and vector-based vaccines. However, there are still several obstacles to overcome before next-generation influenza B vaccines can be widely used, including the challenge of antigenic drift, the extinction of the B/Yamagata lineage, and difficulties in strain selection. There are also other challenges related to public acceptance, vaccine distribution, manufacturing complexity, and regulations. To overcome these challenges, scientists, politicians, and pharmaceutical firms must work together to expedite the development and licensing of vaccines and the establishment of immunization programs. The need for constant monitoring and quick adaptation of vaccines to match the currently circulating strains is further highlighted by the appearance of novel influenza B virus variants. To be ready for future pandemics and influenza B outbreaks, we need better vaccines and better monitoring systems., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: Respiratory viral infections are a major public health challenge and the most diagnosed medical condition, particularly for individuals living in close proximity, like military personnel. We compared the sensitivity and specificity of the Biomeme Franklin TM and Truelab ® RT-PCR thermocyclers to determine which platform is more sensitive and specific at detecting SARS-CoV-2 and influenza A and B viruses., Methodology: RNA extracted from nasopharyngeal swabs of infected and uninfected individuals was tested on the Biomeme Franklin TM at Lackland and the Truelab ® at Wright Patterson Air Force bases., Results: We found an 88% and 71% positivity rate in SARS-CoV-2-infected samples tested on Biomeme and Truelab ® , respectively. Likewise, we found a 49% and 80% positivity rate in influenza-positive samples tested on Biomeme and Truelab ® , respectively. One hundred percent of uninfected swab samples tested negative for SARS-CoV-2 on both platforms. Conversely, 91% and 100% of uninfected swabs tested negative for flu on Biomeme and Truelab ® , respectively., Significance: Differences in specificity and sensitivity in detection of SARS-CoV-2 and influenza between Biomeme and Truelab ® suggest that Truelab ® is a more promising and potentially deployable diagnostic platform for SARS-CoV-2 and influenza viruses' detection in an austere environment.

Exposure to infected animals and their contaminated environments may be the primary cause of human infection with the H7N9 avian influenza virus. However, the transmission characteristics and specific role of various influencing factors in the spread of the epidemic are not clearly understood. Therefore, it is of great significance for scientific research and practical application to explore the influencing factors related to the epidemic. Based on the data of relevant influencing factors and case sample points, this study used the MaxEnt model to test the correlation between human infection with H7N9 avian influenza and influencing factors in China from 2013 to 2017, and scientifically simulated and evaluated the potential risk areas of human infection with H7N9 avian influenza in China. The simulation results show that the epidemic risk is increasing year by year, and the eastern and southeastern coasts have always been high-risk areas. After verification, the model simulation results are generally consistent with the actual outbreak of the epidemic. Population density was the main influencing factor of the epidemic, and the secondary influencing factors included vegetation coverage, precipitation, altitude, poultry slaughter, production value, and temperature. The study revealed the spatial distribution and diffusion rules of the H7N9 epidemic and clarified the key influencing factors. In the future, more variables need to be included to improve the model and provide more accurate support for prevention and control strategies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2025 Yang, Ren, Wang and Dong.)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus are primarily transmitted through droplets or aerosols from patients. The inactivation effects of existing virus control techniques may vary depending on the environmental factors. Therefore, it is important to establish a suitable evaluation system for assessing virus control techniques against airborne viruses for further real-world implementation. This study aimed to assess the inactivating effects of chemical substances on SARS-CoV-2 and influenza A virus in the air using an established evaluation system. A mixture containing SARS-CoV-2 and influenza A virus in diluted saliva was nebulized into the designed 1 m 3 chamber, and the virucidal effects of hypochlorous acid, chlorine dioxide, and ozone in the air samples at 23 ± 1 °C with 50 ± 5% relative humidity were determined using the plaque assay. Both viral infectivity titers decreased depending on chemical substance concentration and exposure time. The concentrations of hypochlorous acid, chlorine dioxide, and ozone in the air reached an approximately 2-log reduction of SARS-CoV-2 infectivity titer within 10 min at 0.02, 1.0, and 1.0 ppm, respectively. SARS-CoV-2 persisted in the air even under conditions where the influenza A virus was inactivated below the detection limits. These findings demonstrate that hypochlorous acid, chlorine dioxide, and ozone are effective in inactivating SARS-CoV-2 and influenza A virus in the air., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s).)

We isolated three genotypes of highly pathogenic avian influenza virus (HPAIV) clade 2.3.4.4b from wild birds infected with H5N1 (n = 12) and H5N8 (n = 1) in Hong Kong SAR 2021-2024. Viruses from two spoonbills from late 2022 were genetically related to a virus from a human in China. Four tested viruses exhibited variable virulence in mice but were susceptible to approved antivirals. No neutralising antibody was detected in 63 age-stratified human sera, suggesting potential risk should the virus adapt to humans.

Introduction. Apolipoprotein E (ApoE), especially the ApoE4 isotype, is suggested to influence the severity of respiratory viral infections; however, this association is still unclear. Hypothesis. The presence of allele ε4 impacts the development of flu-like syndromes. Aim. This study aimed to evaluate the impact of the Apo E4 isoform on the severity and duration of flu-like syndromes, including the coronavirus disease COVID-19. Methodology. This study comprised 280 individuals presenting flu-like symptoms, all genotyped for ApoE isoforms. Data were collected on clinical course, comorbidities, nutritional status, biochemical and inflammatory markers, SARS-CoV-2 reverse transcription PCR results and disease severity (mild, moderate or severe) according to the World Health Organization criteria. The individuals were analysed as a whole and within subgroups based on the SARS-CoV-2-positive (COVID-19 group) or SARS-CoV-2-negative (flu-like syndrome group) test. Results. The frequency of the ε4 allele was similar across the whole population and in both the COVID-19 and flu-like syndrome subgroups (17 and 18%, respectively). No differences were seen in sex, age range, self-reported skin colour, body mass index (BMI), number of comorbidities, vaccination status, biochemical, cytokine and lipid profiles (except for total cholesterol) in the flu-like group when ε4 allele carriers and non-carriers were compared. In the COVID-19 group, the ε4 allele did not correlate with disease severity or duration, number of comorbidities or inflammatory biomarkers. While gender distribution was equal in the overall COVID-19 population, male gender strongly correlated with COVID-19 severity. Multivariate analysis showed that older individuals, male gender, higher BMI and the presence of comorbidities were linked to increased chances of developing moderate and severe disease. IL-4 was the only factor found to reduce the risk of severe COVID-19. Conclusion. The presence of one ɛ4 allele showed no association with the duration and severity of flu-like syndromes, including COVID-19. Nonetheless, SARS-CoV-2-positive individuals tend to be older men with a higher BMI and a tendency to be overweight or with obesity. Regarding COVID-19 severity, BMI, male sex and the number of associated comorbidities were the factors that increased the chance of developing a more severe form of COVID-19.

To evaluate the performance of three rapid influenza diagnostic tests (RIDTs) for detecting influenza A and B viruses compared to RT-PCR. A total of 291 subjects with acute respiratory infections were enrolled. Respiratory specimens were collected and tested for influenza A and B viruses using three RIDTs. The results were compared with those obtained using an RT-PCR assay from Shanghai Berger Medical Technology Co. Ltd. as the reference method. Among the 291 subjects, 119 (40.9%) tested positive for influenza A virus and 38 (13.1%) for influenza B virus by RT-PCR. The sensitivities of the three RIDTs for influenza A virus were 92.4%, 89.1%, and 79.8%, respectively, while their specificities were 98.8%, 98.8%, and 100%, respectively. For influenza B virus, the sensitivities of the three RIDTs were 92.1%, 92.1%, and 73.7%, respectively, and their specificities were 100%, 100%, and 100%, respectively. The positive predictive values (PPVs) for influenza A virus were 98.2%, 98.1%, and 100%, respectively, while the negative predictive values (NPVs) were 94.5%, 92.4%, and 86.9%, respectively. For influenza B virus, the PPVs were all 100%, and the NPVs were 99.2%, 99.2%, and 97.7%, respectively. The three evaluated RIDTs demonstrated high specificity but varied sensitivity for detecting influenza A and B viruses. Negative results from RIDTs should be confirmed by RT-PCR, especially during peak influenza seasons. The high PPVs suggest that positive RIDT results are reliable for influenza diagnosis, while the high NPVs indicate that negative results are more likely to be true negatives., (© 2025 The Author(s). Journal of Medical Virology published by Wiley Periodicals LLC.)

Three hospitals implemented molecular point-of-care tests (POCTs) to screen patients for SARS-CoV-2 infection upon admission during the 2021/2022 influenza season, which in Belgium lasted from January to April 2022. The samples were simultaneously tested for influenza A/B. Influenza positivity at admission was examined in relation to patient characteristics and symptomatology. Influenza POCTs were performed on all patients requiring urgent hospitalization, regardless of the admission reason. A total of 9327 patients were included in the study, of which 411 (4.4%) tested positive for influenza A/B. Asymptomatic infection and mild illness accounted for respectively 11.2% (95% CI: 8.5%-14.6%), and 43.3% (95% CI: 38.6%-48.1%) of the cases. A total of 66% (95% CI: 60%-72%) of all patients in these symptom categories (asymptomatic and mild illness) showed a high viral load (cycle threshold [Ct] < 24). Only in 30 (7.3%, 95% CI: 5.2%-10.2%) of all cases and in two (4.4%, 95% CI: 1.2%-14.5%) of the asymptomatic cases, the symptomatology worsened during hospital stay. Coinfections with both influenza and SARS-CoV-2 occurred in 35 patients (8.5% of all influenza positive patients). There was no difference in symptomatology between patients with co-infections and those with an influenza mono-infection. Patients could not be reliably categorized into carriers with low versus high viral loads based on symptomatology, age, and vaccination status. More than half of the influenza-positive individuals were either asymptomatic or had mild symptoms upon admission, while often carrying high viral loads. Our results show that without screening of patients at hospital admission, a considerable number of patients with a high viral load may be incorrectly classified as being not infectious., (© 2025 Wiley Periodicals LLC.)

The resurgence of influenza viruses as a significant global threat emphasizes the urgent need for innovative antiviral strategies beyond existing treatments. Here, we present the development and evaluation of a novel super-multivalent sialyllactosylated filamentous phage, termed t-6SLPhage, as a potent entry blocker for influenza A viruses. Structural variations in sialyllactosyl ligands, including linkage type, valency, net charge, and spacer length, were systematically explored to identify optimal binding characteristics against target hemagglutinins and influenza viruses. The selected SLPhage equipped with optimal ligands, exhibited exceptional inhibitory potency in in vitro infection inhibition assays. Furthermore, in vivo studies demonstrated its efficacy as both a preventive and therapeutic intervention, even when administered post-exposure at 2 days post-infection, under 4 lethal dose 50% conditions. Remarkably, co-administration with oseltamivir revealed a synergistic effect, suggesting potential combination therapies to enhance efficacy and mitigate resistance. Our findings highlight the efficacy and safety of sialylated filamentous bacteriophages as promising influenza inhibitors. Moreover, the versatility of M13 phages for surface modifications offers avenues for further engineering to enhance therapeutic and preventive performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Highly pathogenic avian influenza (HPAI) clade 2.3.4.4b H5Nx viruses continue to cause episodic incursions and have been detected in more than 12 taxonomic orders encompassing more than 80 avian species, terrestrial and marine mammals, including lactating dairy cows. HPAI H5N1 spillover to dairy cattle creates a new interface for human exposure and raises food safety concerns. The presence of H5N1 genetic material in one out of five retail pasteurized milk samples in the USA has prompted the evaluation of the pasteurization processes for the inactivation of influenza viruses. Our study examined whether pasteurization could effectively inactivate HPAI H5N1 spiked into raw whole milk. First, we heated 1 mL of non-homogenized cow milk samples to attain an internal temperature of 63°C or 72°C and spiked with 6.3 log 10 EID 50 of clade 2.3.4.4b H5N1 virus. Complete inactivation was achieved after incubation of the H5N1 spiked raw milk at 63°C for 30 min. In addition, viral inactivation was observed in seven of eight experimental replicates when treated at 72°C for 15s. In one of the replicates, a 4.44 log 10 virus reduction was achieved, which is about 1 log higher than the average viral quantities detected in bulk milk in affected areas. Therefore, we conclude that pasteurization of milk is an effective strategy for mitigation of the risk of human exposure to milk contaminated with H5N1 virus., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Crown Copyright © 2024. Published by Elsevier Ltd. All rights reserved.)

An increase in spillover events of highly pathogenic avian influenza A(H5N1) viruses to mammals suggests selection of viruses that transmit well in mammals. Here we use air-sampling devices to continuously sample infectious influenza viruses expelled by experimentally infected ferrets. The resulting quantitative virus shedding kinetics data resembled ferret-to-ferret transmission studies and indicated that the absence of transmission observed for earlier A(H5N1) viruses was due to a lack of infectious virus shedding in the air, rather than the absence of necessary mammalian adaptation mutations. Whereas infectious human A(H1N1 pdm ) virus was efficiently shed in the air, infectious 2005 zoonotic and 2024 bovine A(H5N1) viruses were not detected in the air. By contrast, shedding of infectious virus was observed for 1 out of 4 ferrets infected with a 2022 European polecat A(H5N1) virus and a 2024 A(H5N1) virus isolated from a dairy farm worker., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

We report highly pathogenic avian influenza A(H5N1) virus clade 2.3.2.1a in a child traveler returning to Australia from India. The virus was a previously unreported reassortant consisting of clade 2.3.2.1a, 2.3.4.4b, and wild bird low pathogenicity avian influenza gene segments. These findings highlight surveillance gaps in South Asia.

Wastewater-based estimation of infectious disease prevalence in real-time assists public health authorities in developing effective responses to current outbreaks. However, wastewater-based estimation for IAV remains poorly demonstrated, partially because of a lack of knowledge about temporal variation in shedding amount of an IAV-infected person. In this study, we applied two mathematical models to previously collected wastewater and clinical data from four U.S. states during the 2022/2023 influenza season, dominated by the H3N2 subtype. First, we modeled the relationship between the detection probability of IAV in wastewater and FluA case counts, using a logistic function. The model revealed that a 50 % probability of IAV detection in wastewater corresponds to 0.53 (95 % CrI: 0.35-0.78) cases per 100,000 people, as observed in clinical surveillance over two weeks. Next, we applied the previously developed PRESENS model to IAV wastewater concentration data from California, revealing rapid and prolonged virus shedding patterns. The estimated shedding model was incorporated into an extended version of the PRESENS model to assess the variability in the relationship between IAV concentrations and case numbers across other states, including Massachusetts, New Jersey, and Utah. As a result, our analysis demonstrated the effectiveness of normalizing IAV concentrations with PMMoV (Pepper mild mottle virus) to accurately understand spatial distribution patterns of IAV prevalence. We successfully estimated FluA case counts from wastewater concentrations within a factor of two for 80 % of data from a state where 34 % of the state population was monitored by wastewater surveillance. Importantly, wastewater-based estimates provided real-time or leading insights (0-2 days) compared to clinical case detection in the three states, enabling early understanding of the incidence trends by limiting delays in data publication. These findings highlight the potential of wastewater surveillance to detect IAV outbreaks in near real-time and enhance efficiency of the infectious disease management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

A term baby underwent unexpected, fatal resuscitation in the delivery room. The mother suffered from a common cold during her last trimester of pregnancy. All other examinations throughout gestation were normal. Despite immediate, extended and effective resuscitation, heart rate did not exceed 15-20 beats/minute. In the autopsy, fetal myocarditis due to influenza A infection was detected., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Avian influenza A viruses (IAVs) pose a persistent threat to poultry industry worldwide, despite the presence of vaccines. Additionally, reverse-zoonosis transmission potentially introduces human-originated IAVs into poultry and complicates the efforts to control the spread of influenza. Current avian influenza vaccines are primarily based upon the rapidly mutating hemagglutinin (HA) and neuraminidase (NA) glycoproteins, which limit their efficacy against diverse strains of IAVs. Hence, the highly conserved ectodomains of matrix 2 protein (M2e) of IAVs are widely studied as alternatives to the HA and NA. However, the differences in the M2e amino acid sequences between avian and human IAVs generate antibodies that do not cross-react reciprocally with IAVs from other origins. To broaden and enhance the immunogenicity of M2e, we fused two copies each of the M2e derived from avian and human IAVs at the C-terminal end of the Macrobrachium rosenbergii nodavirus (MrNV) capsid protein (NvC). Transmission electron microscopic and dynamic light scattering analyses revealed that the chimeric protein self-assembled into virus-like particles (VLPs). Immunization of chickens with the chimeric VLPs demonstrated a robust induction of broadly reactive immune responses against both the M2e of avian and human IAVs. Additionally, the chimeric VLPs elicited the production of cytotoxic T lymphocytes (CTL), macrophages, as well as a well-balanced Th1 and Th2 population, indicating their potential in activating cell-mediated immune responses in chickens. Furthermore, the chimeric VLPs triggered the production of both Th1- and Th2-cytokines, attesting their potential in mounting a robust and balanced immune response in avian species. This study demonstrated the potential of these chimeric VLPs in stimulating and broadening cross-reactive immune responses in chickens against both avian and human IAVs., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: Avian influenza (AI) H5N6 has replaced H5N1 as the predominant strain, and the increasing number of cases and complex recombination patterns pose significant threats to human health., Methods: The data were collected on human cases of AI H5N6 from the National Surveillance of Notifiable Infectious Disease Programme in Guangxi and used MEGA software to conduct phylogenetic analysis with published reference strains obtained from the GISAID database., Results: Between January 1 and December 31, 2021, 11 cases of human AI H5N6 infection were reported in Guangxi. All HA genes belonged to clade 2.3.4.4, with only one virus belonging to 2.3.4.4h and the remaining viruses falling into 2.3.4.4b. Phylogenetic analysis of the genes was conducted, and some substitutions were detected in the HA gene, M1 protein, and NS1 protein. A close relationship between Guangxi viruses and AI viruses of poultry origin has been observed., Conclusion: Given the contamination of live poultry markets and backyard poultry, AI H5N6 variants and genotypes will continuously emerge; therefore, enhancing surveillance is crucial for pandemic preparedness., Competing Interests: Declarations of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Mammalian membrane sialic acid is the key receptor for influenza virus. Sialidases, the main type of enzyme that can hydrolyze membrane sialic acids in mammalian cells, have the potential to affect the invasion process of influenza viruses, including H1N1. For the first time, this study focused on the regulation mechanism of sialidase NEU1 expression, and revealed that swine-origin influenza (H1N1) virus infection can promote NEU1 expression through histone H3 acetylation, which is regulated by HDAC2 in host cells. This study not only provides evidence for the regulatory mechanisms of mammalian sialase NEU1 expression, but also provides new insights into the host immune defense response against influenza virus infection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Influenza A viruses have caused more documented global pandemics in human history than any other pathogen 1,2 . High pathogenicity avian influenza viruses belonging to the H5N1 subtype are a leading pandemic risk. Two decades after H5N1 'bird flu' became established in poultry in Southeast Asia, its descendants have resurged 3 , setting off a H5N1 panzootic in wild birds that is fuelled by: (1) rapid intercontinental spread, reaching South America and Antarctica for the first time 4,5 ; (2) fast evolution via genomic reassortment 6 ; and (3) frequent spillover into terrestrial 7,8 and marine mammals 9 . The virus has sustained mammal-to-mammal transmission in multiple settings, including European fur farms 10,11 , South American marine mammals 12-15 and US dairy cattle 16-19 , raising questions about whether humans are next. Historically, swine are considered optimal intermediary hosts that help avian influenza viruses adapt to mammals before jumping to humans 20 . However, the altered ecology of H5N1 has opened the door to new evolutionary pathways. Dairy cattle, farmed mink or South American sea lions may have the potential to serve as new mammalian gateways for transmission of avian influenza viruses to humans. In this Perspective, we explore the molecular and ecological factors driving the sudden expansion in H5N1 host range and assess the likelihood of different zoonotic pathways leading to an H5N1 pandemic., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

We show that human myxovirus resistance protein 1 (MxA) suppresses replication of highly pathogenic avian influenza A(H5N1) viruses isolated from mammals in vitro and in MxA-transgenic mice. However, H5N1 can evade MxA restriction through replacement of individual viral polymerase complex components from a human-adapted MxA-resistant strain in vitro.

The severity of the influenza virus infection is largely determined by its ability to invade the human host receptor. This critical step is conducted by utilizing hemagglutinin (HA) due to its binding with sialic acid 2,6 (SA). Though 18 subtypes (H1-H18) of HA have been identified, the most efficient one for conducting the host entry has not yet been resolved. This study aims to assess the severity of infections for HA variants by conducting a comparative docking of H1-H18 with the human SA receptor. Eighteen viral 3D structures were retrieved, minimized, and optimized for docking with human SA. In all retrieved structures, five conserved amino acid residues were selected for docking with human SA. Special protein grids were prepared by locating these five residues in the 18 selected subtypes. Results showed that H3 and H8 exerted the highest standard precision and extra precision docking scores, and the highest binding affinities with the human SA, respectively. Phylogenetic analyses confirmed the actual positioning of the selected 3D structures and showed these docked structures belonged to their usual classes due to the extremely close distances found in each docked subtype compared with its corresponding non-docked structures. H8-SA showed slightly better RMSD and SASA values than H3-SA, while H3-SIA showed more favourable radius of gyration scores than H8-SIA in the majority of the simulation period. Due to the highest affinity of binding of H3 and H8 with the human receptor, special caution should be exercised regarding any possible outbreak mediated by these subtypes in human populations. However, it is important to acknowledge a limitation inherent to the computational approach; it may hold relative rather than absolute significance. Further research is needed to deepen our understanding of the intricate interplay between HA variants and the host receptor, taking into account the broader context of viral infection dynamics.Communicated by Ramaswamy H. Sarma.

Objectives: To analyze the molecular epidemiological characteristics of influenza viruses in influenza-like cases in Chongqing Hi-Tech Zone, China, to provide data support and a scientific basis for optimizing influenza prevention and control strategies in the region., Materials and Methods: A retrospective analysis was conducted on the molecular epidemiological characteristics of influenza viruses in influenza-like cases at a hospital in Chongqing Hi-Tech Zone from 2021 to 2024. Colloidal gold detection of viral antibodies, fluorescent PCR detection of nucleic acids, and gene sequencing were used to identify the different subtypes., Results: Among 39,986 ILI specimens tested using the immunocolloid gold method, 6,616 influenza viruses were detected, with a detection rate of 16.54%. Infections included 4,464 influenza A viruses (67.50%), 2,033 influenza B viruses (30.73%), and 119 co-infections of influenza A and B viruses (1.77%).In this region, H3N2 was the predominant subtype of influenza A, and Victoria was the main subtype of influenza B., Conclusion: Influenza epidemics in the winter and spring seasons in Chongqing Hi-Tech Zone were predominantly caused by influenza A, with influenza B also circulating. Influenza A strains were mainly H3N2, while influenza B strains were primarily Victoria., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

To optimize seasonal influenza control and prevention programs in regions with potentially complicated seasonal patterns. Descriptive epidemiology was used to analyze the etiology of influenza, and chi-square tests were used to compare the epidemic patterns among different influenza virus types and subtypes/lineages. From January 2010 to December 2019, a total of 63,626 ILI cases were reported in Chongqing and 14,136 (22.22%) were laboratory-confirmed influenza cases. The proportions of specimens positive for influenza A and influenza B were 13.32% (8,478/63,626) and 8.86% (5,639/63,626), respectively. The proportion of positive specimens for influenza A reached the highest in winter (23.33%), while the proportion of positive specimens for influenza B reached the highest in spring (11.88%). Children aged 5-14 years old had the highest proportion of positive specimens for influenza. The influenza virus types/subtypes positive was significantly different by seasons and age groups ( P <.001), but not by gender ( p  = .436). The vaccine strains were matched to the circulating influenza virus strains in all other years except for 2018 (vaccine strain was B/Colorado/06/2017; circulating strain was B/Yamagata). The study showed significant variations in epidemic patterns, including seasonal epidemic period and age distributions, among different influenza types, subtypes/lineages in Chongqing. Influenza vaccines matched to the circulating influenza virus strain in nine of the ten years. To prevent and mitigate the influenza outbreaks in this area, high risk population, especially children aged 5-14 years, are encouraged to get vaccinated against influenza before the epidemic seasons.

Imbalance of airway proteases and antiproteases has been implicated in diseases such as COPD and environmental exposures including cigarette smoke and ozone. To initiate infection, endogenous proteases are commandeered by respiratory viruses upon encountering the airway epithelium. The airway proteolytic environment likely contains redundant antiproteases and proteases with diverse catalytic mechanisms, however a proteomic profile of these enzymes and inhibitors in airway samples has not been reported. The objective of this study was to first profile extracellular proteases and antiproteases using human airway epithelial cell cultures and ex vivo nasal epithelial lining fluid (NELF) samples. Secondly, we present an optimized method for probing the proteolytic environment of airway surface liquid samples (in vitro and ex vivo) using fluorogenic peptides modeling the cleavage sites of respiratory viruses. We detected 48 proteases in the apical wash of cultured human nasal epithelial cells (HNECs) (n = 6) and 57 in NELF (n = 13) samples from healthy human subjects using mass-spectrometry based proteomics. Additionally, we detected 29 and 48 antiproteases in the HNEC apical washes and NELF, respectively. We observed large interindividual variability in rate of cleavage of an Influenza H1 peptide in the ex vivo clinical samples. Since protease and antiprotease levels have been found to be altered in the airways of smokers, we compared proteolytic cleavage in ex vivo nasal lavage samples from male/female smokers and non-smokers. There was a statistically significant increase in proteolysis of Influenza H1 in NLF from male smokers compared to female smokers. Furthermore, we measured cleavage of the S1/S2 site of SARS-CoV, SARS-CoV-2, and SARS-CoV-2 Delta peptides in various airway samples, suggesting the method could be used for other viruses of public health relevance. This assay presents a direct and efficient method of evaluating the proteolytic environment of human airway samples in assessment of therapeutic treatment, exposure, or underlying disease., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Brocke et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: In Europe, the age indication for the MF59-adjuvanted quadrivalent influenza vaccine (aQIV) has recently been extended from ≥65 to ≥50 years. Considering that the earliest approval of its trivalent formulation (aTIV) in Italy was for people aged ≥12 years, we aimed to systematically appraise data on the immunogenicity, efficacy, and safety of aTIV/aQIV in non-elderly adults., Methods: A systematic literature review was conducted according to the available guidelines and studies were searched in MEDLINE, Biological Abstracts, Web of Science, Cochrane Library and clinical trial registries. Studies on absolute and relative immunogenicity, efficacy, effectiveness, and safety of aTIV/aQIV in non-elderly adults (<65 years) were potentially eligible. These endpoints were analyzed by virus (sub)types and characteristics of vaccinees. Fixed- and random-effects meta-analyses were performed for data synthesis. Protocol registration: CRD42024512472., Results: Twenty-four publications were analyzed. aTIV/aQIV was more immunogenic than non-adjuvanted vaccines towards vaccine-like strains: the absolute differences in seroconversion rates were 8.8% (95% CI: 3.7%, 14.0%), 13.1% (95% CI: 6.7%, 19.6%) and 11.7% (95% CI: 7.2%, 16.2%) for A(H1N1), A(H3N2), and B strains, respectively. This immunogenicity advantage was more pronounced in immunosuppressed adults. Additionally, aTIV/aQIV was more immunogenic than non-adjuvanted counterparts towards heterologous A(H3N2) strains with a 10.7% (95% CI: 3.2%, 18.2%) difference in seroconversion rates. Data on antibody persistence and efficacy were limited and inconclusive. Overall, aTIV/aQIV was judged safe and well tolerated, although reactogenic events were more frequent in aTIV/aQIV recipients versus comparators. Serious adverse events were uncommon and no difference (risk ratio 1.02; 95% CI: 0.64, 1.63) between aTIV/aQIV and non-adjuvanted formulations was found., Conclusions: In non-elderly adults, aTIV/aQIV is safe and generally more immunogenic than non-adjuvanted standard-dose vaccines., Competing Interests: EF and MS are employees Seqirus S.r.L. AD was previously an employee of Seqirus S.r.L. AD and CST received a fee from Seqirus S.r.L. for conducting this systematic review. This does not alter our adherence to PLOS ONE policies on sharing data and materials. There are no patents, products in development or marketed products associated with this research to declare., (Copyright: © 2024 Domnich et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Respiratory interventions including noninvasive ventilation, continuous positive airway pressure and high-flow nasal oxygen generated infectious aerosols may increase risk of airborne disease (SARS-CoV-2, influenza virus) transmission to healthcare workers. We developed and tested a prototype portable UV-C 254 device to sterilize high flows of viral-contaminated air from a simulated patient source at airflow rates of up to 100 l/m. Our device consisted of a central quartz tube surrounded 6 high-output UV-C 254 lamps, within a larger cylinder allowing recirculation past the UV-C 254 lamps a second time before exiting the device. Testing was with nebulized A/PR/8/34 (H1N1) influenza virus. RNA extraction and qRT-PCR showed virus transited through the prototype. Turning on varying numbers of lamps controlled the dose of UVC. Viability experiments at low, medium and high (100 l/min) flows of contaminated gas were conducted with 6, 4, 2 and 1 lamp activated (single-pass and recirculation were tested). Our data show 5-log reduction in plaque forming units from a single lamp (single- pass and recirculated conditions) at high and low flows. UVC dose at 100 l/m was calculated at 11.6 mJ/cm 2 single pass and 104 mJ/cm 2 recirculated. The protype device shows high efficacy in killing nebulized influenza virus in a high flow of contaminated air., Competing Interests: Declarations. Competing interests: The A.G.-S laboratory has received research support from GSK, Pfizer, Senhwa Biosciences, Kenall Manufacturing, Blade Therapeutics, Avimex, Johnson & Johnson, Dynavax, 7Hills Pharma, Pharmamar, ImmunityBio, Accurius, Nanocomposix, Hexamer, N-fold LLC, Model Medicines, Atea Pharma, Applied Biological Laboratories and Merck, outside of the reported work. A.G.-S. has consulting agreements for the following companies involving cash and/or stock: Castlevax, Amovir, Vivaldi Biosciences, Contrafect, 7Hills Pharma, Avimex, Pagoda, Accurius, Esperovax, Farmak, Applied Biological Laboratories, Pharmamar, CureLab Oncology, CureLab Veterinary, Synairgen, Paratus, Pfizer and Prosetta, outside of the reported work. A.G.-S. has been an invited speaker in meeting events organized by Seqirus, Janssen, Abbott and Astrazeneca. A.G.-S. is inventor on patents and patent applications on the use of antivirals and vaccines for the treatment and prevention of virus infections and cancer, owned by the Icahn School of Medicine at Mount Sinai, New York. The MS laboratory received unrelated research support as sponsored research agreements from ArgenX BV, Phio Pharmaceuticals, 7Hills Pharma LLC and Moderna, Inc. All other authors did not have a competing interest., (© 2024. The Author(s).)

Zoonotic infections (swine-human) caused by influenza A viruses (IAVs) have been reported and linked to close contact between these species. Here, we describe eight human IAV variant infections (6 mild and 2 severe cases, including 1 death) detected in Paraná, Brazil, during 2020-2023. Genomes recovered were closely related to Brazilian swIAVs of three major lineages (1 A.3.3.2/pdm09, 1B/human-like, and H3.1990.5), including three H1N1v, two H1N2v, two H3N2v and one H1v. Five H1v were closely related to pdm09 lineage, one H1v (H1N2v) grouped within 1B.2.3 clade, and the two H3v grouped within a clade composed exclusively of Brazilian H3 swIAV (clade H3.1990.5.1). Internal gene segments were closely related to H1N1pdm09 isolated from pigs. IAV variant rarely result in sustained transmission between people, however the potential to develop such ability is of concern and must not be underestimated. This study brings into focus the need for continuous influenza surveillance and timely risk assessment., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Human ANP32A/B (huANP32A/B) poorly support the polymerase activity of avian influenza viruses (AIVs), thereby limiting interspecies transmission of AIVs from birds to humans. The SUMO-interacting motif (SIM) within NS2 promotes the adaptation of AIV polymerase to huANP32A/B via a yet undisclosed mechanism. Here we show that huANP32A/B are SUMOylated by the E3 SUMO ligase PIAS2α, and deSUMOylated by SENP1. SUMO modification of huANP32A/B results in the recruitment of NS2, thereby facilitating huANP32A/B-supported AIV polymerase activity. Such a SUMO-dependent recruitment of NS2 is mediated by its association with huANP32A/B via the SIM-SUMO interaction module, where K68/K153-SUMO in huANP32A or K68/K116-SUMO in huANP32B interacts with the NS2-SIM. The SIM-SUMO-mediated interactions between NS2 and huANP32A/B function to promote AIV polymerase activity by positively regulating AIV vRNP-huANP32A/B interactions and AIV vRNP assembly. Our study offers insights into the mechanism of NS2-SIM in facilitating AIVs adaptation to mammals., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)