Lipid nanoparticle-encapsulated DNA vaccine confers protection against swine and human-origin H1N1 influenza viruses.

In 2009, a novel swine-origin H1N1 virus emerged, causing a pandemic. The virus, known as H1N1pdm09, quickly displaced the circulating H1 lineage and became the dominant seasonal influenza A virus subtype infecting humans. Human-to-swine spillovers of the H1N1pdm09 have occurred frequently, and each occurrence has led to sustained transmission of the human-origin H1N1pdm09 within swine populations. In the present study, we developed a lipid nanoparticle-based DNA vaccine (LNP-DNA) containing the hemagglutinin gene of a swine-origin H1N1pdm09. In pigs, this LNP-DNA vaccine induced a robust antibody response after a single intramuscular immunization and protected the pigs against challenge infection with the homologous swine-origin H1N1pdm09 virus. In a mouse model, the LNP-DNA vaccine induced antibody and T-cell responses and protected mice against lethal challenge with a mouse-adapted human-origin H1N1pdm09 virus. These findings demonstrate the potential of the LNP-DNA vaccine to protect against both swine- and human-origin H1N1pdm09 viruses. IMPORTANCE: Swine influenza A virus (IAV) is widespread and causes significant economic losses to the swine industry. Moreover, bidirectional transmission of IAV between swine and humans commonly occurs. Once introduced into the swine population, human-origin IAV often reassorts with endemic swine IAV, resulting in reassortant viruses. Thus, it is imperative to develop a vaccine that is not only effective against IAV strains endemic in swine but also capable of preventing the spillover of human-origin IAV. In this study, we developed a lipid nanoparticle-encapsulated DNA plasmid vaccine (LNP-DNA) that demonstrates efficacy against both swine- and human-origin H1N1 viruses. The LNP-DNA vaccines are non-infectious and non-viable, meeting the criteria to serve as a vaccine platform for rapidly updating vaccines. Collectively, this LNP-DNA vaccine approach holds great potential for alleviating the impact of IAV on the swine industry and preventing the emergence of reassortant IAV strains.

Signals from intestinal microbiota mediate the crosstalk between the lung-gut axis in an influenza infection mouse model.

Introduction: Introduction: The influenza virus primarily targets the respiratory tract, yet both the respiratory and intestinal systems suffer damage during infection. The connection between lung and intestinal damage remains unclear. Methods: Our experiment employs 16S rRNA technology and Liquid Chromatography-Mass Spectrometry (LC-MS) to detect the impact of influenza virus infection on the fecal content and metabolites in mice. Additionally, it investigates the effect of influenza virus infection on intestinal damage and its underlying mechanisms through HE staining, Western blot, Q-PCR, and flow cytometry. Results: Our study found that influenza virus infection caused significant damage to both the lungs and intestines, with the virus detected exclusively in the lungs. Antibiotic treatment worsened the severity of lung and intestinal damage. Moreover, mRNA levels of Toll-like receptor 7 (TLR7) and Interferon-b (IFN-b) significantly increased in the lungs post-infection. Analysis of intestinal microbiota revealed notable shifts in composition after influenza infection, including increased Enterobacteriaceae and decreased Lactobacillaceae. Conversely, antibiotic treatment reduced microbial diversity, notably affecting Firmicutes, Proteobacteria, and Bacteroidetes. Metabolomics showed altered amino acid metabolism pathways due to influenza infection and antibiotics. Abnormal expression of indoleamine 2,3-dioxygenase 1 (IDO1) in the colon disrupted the balance between helper T17 cells (Th17) and regulatory T cells (Treg cells) in the intestine. Mice infected with the influenza virus and supplemented with tryptophan and Lactobacillus showed reduced lung and intestinal damage, decreased Enterobacteriaceae levels in the intestine, and decreased IDO1 activity. Discussion: Overall, influenza infection caused damage to lung and intestinal tissues, disrupted intestinal microbiota and metabolites, and affected Th17/Treg balance. Antibiotic treatment exacerbated these effects. Supplementation with tryptophan and Lactobacillus improved lung and intestinal health, highlighting a new understanding of the lung-intestine connection in influenza-induced intestinal disease.

Unraveling Novel Strategies: Targeting Miz1 for Degradation to Enhance Antiviral Defense against Influenza A Virus.

The ubiquitin system has been shown to play an important role in regulation of immune responses during viral infection. In a recent article published in Science Signaling, Wu and colleagues revealed that transcriptional factor Miz1 plays a pro-viral role in influenza A virus (IAV) infection by suppressing type I interferons (IFNs) production through recruiting HDAC1 to ifnb1 promoter. They show that a series of E3 ligases combinatorially regulates Miz1 ubiquitination and degradation and modulates IFNs production and viral replication.

Obesity impairs ciliary function and mucociliary clearance in the murine airway epithelium.

Obesity is a risk factor for increased morbidity and mortality in viral respiratory infection. Mucociliary clearance (MCC) in the airway is the primary host defense against viral infections. However, the impact of obesity on MCC is unclear, prompting this study. Using murine tracheal tissue culture and in vitro influenza A virus (IAV) infection models, we analyzed cilia-driven flow and ciliary beat frequency (CBF) in the airway epithelium to evaluate MCC. Short-term IAV infection increased cilia-driven flow and CBF in control mice, but not in high-fat diet-induced obese mice. Basal cilia-driven flow and CBF were also lower in obese mice than in control mice. Mechanistically, the increase of extracellular adenosine triphosphate (ATP) release during IAV infection, which was observed in the control mice, was abolished in the obese mice, although the addition of ATP increased cilia-driven flow and CBF both in control and obese mice to a similar extent. Additionally, RNA sequencing and reverse transcription-polymerase chain reaction revealed the downregulation of several cilia-related genes, including Dnah1, Dnal1, Armc4, and Ttc12 (the dynein-related genes); Ulk4 (the polychaete differentiation gene); Cep164 (the ciliogenesis and intraflagellar transport gene); Rsph4a, Cfap206, and Ppil6 (the radial spoke structure and assembly gene); and Drc3(the nexin-dynein regulatory complex genes) in obese murine tracheal tissues compared to their control levels. In conclusion, our studies demonstrate that obesity attenuates MCC under basal conditions and during IAV infection by downregulating the expression of cilia-related genes and suppressing the release of extracellular ATP, thereby increasing the susceptibility and severity of IAV infection.

Inhibition of transient receptor potential vanilloid 1 reduces shedding and transmission during Streptococcus pneumoniae co-infection with influenza.

Transmission is the first step for a microorganism to establish colonization in the respiratory tract and subsequent development of infectious disease. Streptococcus pneumoniae is a leading pathogen that colonizes the mucosal surfaces of the human upper respiratory tract and causes subsequent transmission and invasive infections especially in co-infection with influenza A virus. Host factors contributing to respiratory contagion are poorly understood. Transient receptor potential vanilloid (TRPV) channels have various roles in response to microoorganism. Inhibition of TRPV exacerbates invasive infection by Streptococcus pneumoniae, but it is unclear how TRPV channels influence pneumococcal transmission. Here, we describe the effect of inhibition of TRPV1 on pneumococcal transmission. We adopted a TRPV1-deficient infant mouse model of pneumococcal transmission during co-infection with influenza A virus. We also analyzed the expression of nasal mucin or pro-inflammatory cytokines. TRPV1 deficiency attenuated pneumococcal transmission and shedding during co-infection with influenza A virus. TRPV1 deficiency suppressed the expression of nasal mucin. In addition, there were increases in the expression of tumor necrosis factor-α and type I interferon, followed by the suppressed replication of influenza A virus in TRPV1-deficient mice. Inhibition of TRPV1 was shown to attenuate pneumococcal transmission by reducing shedding through the suppression of nasal mucin during co-infection with influenza A virus. Inhibition of TRPV1 suppressed nasal mucin by modulation of pro-inflammatory responses and regulation of replication of influenza A virus. TRPV1 could be a new target in preventive strategy against pneumococcal transmission.

Inhibition of RAN Attenuates Influenza A Virus Replication and Nucleoprotein Nuclear Export.

Nuclear export of the viral ribonucleoprotein (vRNP) is a critical step in the influenza A virus (IAV) life cycle and may be an effective target for the development of anti- IAV drugs. The host factor ras-related nuclear protein (RAN) is known to participates in the life cycle of several viruses, but its role in influenza virus replication remains unknown. In the present study, we aimed to determine the function of RAN in influenza virus replication using different cell lines and subtype strains. We found that RAN is essential for the nuclear export of vRNP, as it enhances the binding affinity of XPO1 toward the viral nuclear export protein NS2. Depletion of RAN constrained the vRNP complex in the nucleus and attenuated the replication of various subtypes of influenza virus. Using in silico compound screening, we identified bepotastine could dissociate the RAN-XPO1-vRNP trimeric complex and exhibit potent antiviral activity against influenza virus both in vitro and in vivo. This study demonstrates the important role of RAN in IAV replication and suggests its potential use as an antiviral agent.

Risk for Waterborne Transmission and Environmental Persistence of Avian Influenza Virus in a Wildlife/Domestic Interface in Mexico.

Aquatic habitats provide a bridge for influenza transmission among wild and domestic species. However, water sources pose highly variable physicochemical and ecological characteristics that affect avian influenza virus (AIV) stability. Therefore, the risk of survival or transmissibility of AIV in the environment is quite variable and has been understudied. In this study, we determine the risk of waterborne transmission and environmental persistence of AIV in a wild/domestic bird interface in the Central Mexico plateau (North America) during the winter season using a multi-criteria decision analysis (MCDA). A total of 13 eco-epidemiological factors were selected from public-access databases to develop the risk assessment. The MCDA showed that the Atarasquillo wetland presents a higher persistence risk in January. Likewise, most of the backyard poultry farms at this wild-domestic interface present a high persistence risk (50%). Our results suggest that drinking water may represent a more enabling environment for AIV persistence in contrast with wastewater. Moreover, almost all backyard poultry farms evidence a moderate or high risk of waterborne transmission especially farms close to water bodies. The wildlife/domestic bird interface on the Atarasquillo wetland holds eco-epidemiological factors such as the presence of farms in flood-prone areas, the poultry access to outdoor water, and the use of drinking-water troughs among multiple animal species that may enhance waterborne transmission of AIV. These findings highlight the relevance of understanding the influence of multiple factors on AIV ecology for early intervention and long-term control strategies.

Exploiting the Affimer platform against influenza A virus.

Influenza A virus (IAV) is well known for its pandemic potential. While current surveillance and vaccination strategies are highly effective, therapeutic approaches are often short-lived due to the high mutation rates of IAV. Recently, monoclonal antibodies (mAbs) have emerged as a promising therapeutic approach, both against current strains and future IAV pandemics. In addition to mAbs, several antibody-like alternatives exist, which aim to improve upon mAbs. Among these, Affimers stand out for their short development time, high expression levels in Escherichia coli, and animal-free production. In this study, we utilized the Affimer platform to isolate and produce specific and potent inhibitors of IAV. Using a monomeric version of the IAV trimeric hemagglutinin (HA) fusion protein, we isolated 12 Affimers that inhibit IAV infection in vitro. Two of these Affimers were characterized in detail and exhibited nanomolar-binding affinities to the target H3 HA protein, specifically binding to the HA1 head domain. Cryo-electron microscopy (cryo-EM), employing a novel spray approach to prepare cryo-grids, allowed us to image HA-Affimer complexes. Combined with functional assays, we determined that these Affimers inhibit IAV by blocking the interaction of HA with the host-cell receptor, sialic acid. Furthermore, these Affimers inhibited IAV strains closely related to the one used for their isolation. Overall, our results support the use of Affimers as a viable alternative to existing targeted therapies for IAV and highlight their potential as diagnostic reagents. IMPORTANCE: Influenza A virus is one of the few viruses that can cause devastating pandemics. Due to the high mutation rates of this virus, annual vaccination is required, and antivirals are short-lived. Monoclonal antibodies present a promising approach to tackle influenza virus infections but are associated with some limitations. To improve on this strategy, we explored the Affimer platform, which are antibody-like proteins made in bacteria. By performing phage-display against a monomeric version of influenza virus fusion protein, an established viral target, we were able to isolate Affimers that inhibit influenza virus infection in vitro. We characterized the mechanism of inhibition of the Affimers by using assays targeting different stages of the viral replication cycle. We additionally characterized HA-Affimer complex structure, using a novel approach to prepare samples for cryo-electron microscopy. Overall, these results show that Affimers are a promising tool against influenza virus infection.

Preventive, safety and control measures against Avian Influenza A(H5N1) in occupationally exposed groups: A scoping review.

Introduction: During the outbreak of avian influenza, A (H5N1) (IA) in wild and domestic birds recorded in January 2023, the epidemiological alert has been extended due to its potential contagion to humans, particularly in those exposed occupational groups. Objective: to identify the primary occupational risk groups, as well as the preventive, safety, and control measures against IA intended or implemented in these positions. Material and methods: A systematic search was conducted in Pubmed, Scopus, Web of science, Scielo and literature databases. Scientific articles, normative documents, and technical reports identifying vulnerable occupational groups and preventive measures against IA were included. Two authors conducted a full-text review, extracting information independently, and findings were summarized narratively. Results: A total of 5518 documents were identified, and 30 reports were included. 20% of the reports were published in 2023, 13/30 were affiliated to a university institution. Occupationally exposed groups were identified both directly and indirectly. 63.3% of reports identified breeders, poultry farmers and sellers as the most concerning occupational group, while 60% identified biosecurity practices (use of PPE, handwashing) as the primary measure against IA, followed by strategies such as education (training and capacity-building). Conclusion: Occupational groups of interest were identified, primarily those involved in sales, commerce, and the handling of bird waste with potential exposure to IA. Furthermore, the maintenance of biosecurity measures, cleaning-disinfection practices, and educational strategies in workplace settings are recommended.

Shufeng Jiedu capsule alleviates influenza A (H1N1) virus induced acute lung injury by regulating the lung inflammatory microenvironment.

Background: Death caused by respiratory tract infection is one of the leading causes of death in the world today. Shufeng Jiedu Capsule (SFJDC) is a traditional Chinese medicine that has been widely used clinically for coronavirus disease 2019 (COVID-19), H1N1 influenza virus pneumonia and other diseases. Its pharmacological effect is to inhibit inflammation and improve the body's ability to clear viruses. However, the mechanism of SFJDC in the treatment of viral pneumonia, especially its effect on the inflammatory-immune microenvironment of lung tissue remains unclear. Methods: Mice with H1N1 influenza virus pneumonia were used as a model to verify the efficacy of SFJDC through death protection, lung index, viral load, and HE staining of lung tissue. The levels of inflammatory cytokines and chemokines in lung tissue were investigated by multi-analyte immunoassay. The number and proportion of cells in peripheral blood were detected by blood routine. The percentage of infiltrating immune cells in lung tissue was detected by flow cytometry and immunofluorescence. Results: SFJDC (2.2 g/kg·d-1 and 1.1 g/kg·d-1) increased survival rate (P＜0.01, P＜0.05), prolonged the survival period of mice, and alleviated the histopathological damage in lung (P＜0.01). SFJDC (2.2 g/kg·d-1, 1.1 g/kg·d-1 and 0.055 g/kg·d-1) increased body weight(P＜0.01, P＜0.05), improved activity status, reduced the lung index (P＜0.01, P＜0.05) and viral load (P＜0.01). SFJDC (2.2 g/kg·d-1 and 1.1 g/kg·d-1) reduced interleukin-1ß (IL-1ß), interleukin-18(IL-18), tumour necrosis factor α (TNF-α), monocyte chemoattractant protein (MCP), chemokine (C-X-C motif) ligand 1 (CXCL1) (P＜0.01, P＜0.05), and SFJDC (2.2 g/kg·d-1) increased IL-10 levels (P＜0.05) to regulate inflammation. SFJDC (2.2 g/kg·d-1) increased the percentages of CD4+ T cells (P＜0.01), CD8+ T cells (P＜0.05), and B cells(P＜0.05), and decreased F4/80+ macrophages (P＜0.05). Conclusion: Our findings indicated that SFJDC could inhibit inflammation and lung injury while maintaining the function of the adaptive immune response mediated by T and B cells, and promote the clearance of the virus, thereby treating influenza A (H1N1) virus-induced pneumonia.

Influenza virus infection activates TAK1 to suppress RIPK3-independent apoptosis and RIPK1-dependent necroptosis.

Many DNA viruses develop various strategies to inhibit cell death to facilitate their replication. However, whether influenza A virus (IAV), a fast-replicating RNA virus, attenuates cell death remains unknown. Here, we report that IAV infection induces TAK1 phosphorylation in a murine alveolar epithelial cell line (LET1) and a murine fibroblastoma cell line (L929). The TAK1-specific inhibitor 5Z-7-Oxzeneonal (5Z) and TAK1 knockout significantly enhance IAV-induced apoptosis, as evidenced by increased PARP, caspase-8, and caspase-3 cleavage. TAK1 inhibition also increases necroptosis as evidenced by increased RIPK1S166, RIPK3T231/S232, and MLKLS345 phosphorylation. Mechanistically, TAK1 activates IKK, which phosphorylates RIPK1S25 and inhibits its activation. TAK1 also activates p38 and its downstream kinase MK2, which phosphorylates RIPK1S321 but does not affect RIPK1 activation. Further investigation revealed that the RIPK1 inhibitor Nec-1 and RIPK1 knockout abrogate IAV-induced apoptosis and necroptosis; re-expression of wild-type but not kinase-dead (KD)-RIPK1 restores IAV-induced cell death. ZBP1 knockout abrogates IAV-induced cell death, whereas RIPK3 knockout inhibits IAV-induced necroptosis but not apoptosis. 5Z treatment enhances IAV-induced cell death and slightly reduces the inflammatory response in the lungs of H1N1 virus-infected mice and prolongs the survival of IAV-infected mice. Our study provides evidence that IAV activates TAK1 to suppress RIPK1-dependent apoptosis and necroptosis, and that RIPK3 is required for IAV-induced necroptosis but not apoptosis in epithelial cells.

Melatonin Rescues Influenza A Virus-Induced Cellular Energy Exhaustion via OMA1-OPA1-S in Acute Exacerbation of COPD.

Although rapid progression and a poor prognosis in influenza A virus (IAV) infection-induced acute exacerbation of chronic obstructive pulmonary disease (AECOPD) are frequently associated with metabolic energy disorders, the underlying mechanisms and rescue strategies remain unknown. We herein demonstrated that the level of resting energy expenditure increased significantly in IAV-induced AECOPD patients and that cellular energy exhaustion emerged earlier and more significantly in IAV-infected primary COPD bronchial epithelial (pDHBE) cells. The differentially expressed genes were enriched in the oxidative phosphorylation (OXPHOS) pathway; additionally, we consistently uncovered much earlier ATP exhaustion, more severe mitochondrial structural destruction and dysfunction, and OXPHOS impairment in IAV-inoculated pDHBE cells, and these changes were rescued by melatonin. The level of OMA1-dependent cleavage of OPA1 in the mitochondrial inner membrane and the shift in energy metabolism from OXPHOS to glycolysis were significantly increased in IAV-infected pDHBE cells; however, these changes were rescued by OMA1-siRNA or melatonin further treatment. Collectively, our data revealed that melatonin rescued IAV-induced cellular energy exhaustion via OMA1-OPA1-S to improve the clinical prognosis in COPD. This treatment may serve as a potential therapeutic agent for patients in which AECOPD is induced by IAV.

Strain-dependent variations in replication of European clade 2.3.4.4b influenza A(H5N1) viruses in bovine cells and thermal inactivation in semi-skimmed or whole milk.

We investigated the thermostability of four European avian influenza A(H5N1) viruses in whole and semi-skimmed milk and their replication in bovine kidney and lung cells amid the current influenza A(H5N1) dairy cattle outbreak in the United States. Results showed strain-dependent differences in thermal inactivation, particularly in whole milk, and variable replication efficacy in lung cells. These findings support assessing the inactivation of European H5N1 viruses in milk and their replication in bovine cells, aiding biosafety protocols and public health measures.

Vagal-α7 nicotinic acetylcholine receptor signaling exacerbates influenza severity by promoting lung epithelial cell infection.

The vagus nerve circuit, operating through the alpha-7 nicotinic acetylcholine receptor (α7 nAChR), regulates the inflammatory response by influencing immune cells. However, the role of vagal-α7 nAChR signaling in influenza virus infection is unclear. In particular, does vagal-α7 nAChR signaling impact the infection of alveolar epithelial cells (AECs), the primary target cells of influenza virus? Here, we demonstrated a distinct role of α7 nAChR in type II AECs compared to its role in immune cells during influenza infection. We found that deletion of Chrna7 (encoding gene of α7 nAChR) in type II AECs or disruption of vagal circuits reduced lung influenza infection and protected mice from influenza-induced lung injury. We further unveiled that activation of α7 nAChR enhanced influenza infection through PTP1B-NEDD4L-ASK1-p38MAPK pathway. Mechanistically, activation of α7 nAChR signaling decreased p38MAPK phosphorylation during infection, facilitating the nuclear export of influenza viral ribonucleoproteins and thereby promoting infection. Taken together, our findings reveal a mechanism mediated by vagal-α7 nAChR signaling that promotes influenza viral infection and exacerbates disease severity. Targeting vagal-α7 nAChR signaling may offer novel strategies for combating influenza virus infections.

A small molecule compound targeting hemagglutinin inhibits influenza A virus and exhibits broad-spectrum antiviral activity.

Influenza A virus (IAV) is a widespread pathogen that poses a significant threat to human health, causing pandemics with high mortality and pathogenicity. Given the emergence of increasingly drug-resistant strains of IAV, currently available antiviral drugs have been reported to be inadequate to meet clinical demands. Therefore, continuous exploration of safe, effective and broad-spectrum antiviral medications is urgently required. Here, we found that the small molecule compound J1 exhibited low toxicity both in vitro and in vivo. Moreover, J1 exhibits broad-spectrum antiviral activity against enveloped viruses, including IAV, respiratory syncytial virus (RSV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human coronavirus OC43 (HCoV-OC43), herpes simplex virus type 1 (HSV-1) and HSV-2. In this study, we explored the inhibitory effects and mechanism of action of J1 on IAV in vivo and in vitro. The results showed that J1 inhibited infection by IAV strains, including H1N1, H7N9, H5N1 and H3N2, as well as by oseltamivir-resistant strains. Mechanistic studies have shown that J1 blocks IAV infection mainly through specific interactions with the influenza virus hemagglutinin HA2 subunit, thereby blocking membrane fusion. BALB/c mice were used to establish a model of acute lung injury (ALI) induced by IAV. Treatment with J1 increased survival rates and reduced viral titers, lung index and lung inflammatory damage in virus-infected mice. In conclusion, J1 possesses significant anti-IAV effects in vitro and in vivo, providing insights into the development of broad-spectrum antivirals against future pandemics.

MEK-inhibitor treatment reduces the induction of regulatory T cells in mice after influenza A virus infection.

Regulatory T cells (Tregs) play a crucial and complex role in balancing the immune response to viral infection. Primarily, they serve to regulate the immune response by limiting the expression of proinflammatory cytokines, reducing inflammation in infected tissue, and limiting virus-specific T cell responses. But excessive activity of Tregs can also be detrimental and hinder the ability to effectively clear viral infection, leading to prolonged disease and potential worsening of disease severity. Not much is known about the impact of Tregs during severe influenza. In the present study, we show that CD4+/CD25+FoxP3+ Tregs are strongly involved in disease progression during influenza A virus (IAV) infection in mice. By comparing sublethal with lethal dose infection in vivo, we found that not the viral load but an increased number of CD4+/CD25+FoxP3+ Tregs may impair the immune response by suppressing virus specific CD8+ T cells and favors disease progression. Moreover, the transfer of induced Tregs into mice with mild disease symptoms had a negative and prolonged effect on disease outcome, emphasizing their importance for pathogenesis. Furthermore, treatment with MEK-inhibitors resulted in a significant reduction of induced Tregs in vitro and in vivo and positively influenced the progression of the disease. Our results demonstrate that CD4+/CD25+FoxP3+ Tregs are involved in the pathogenesis of severe influenza and indicate the potential of the MEK-inhibitor zapnometinib to modulate CD4+/CD25+FoxP3+ Tregs. Thus, making MEK-inhibitors even more promising for the treatment of severe influenza virus infections.

Phylogenetic and mutational analysis of H10N3 avian influenza A virus in China: potential threats to human health.

In recent years, the avian influenza virus has emerged as a significant threat to both human and public health. This study focuses on a patient infected with the H10N3 subtype of avian influenza virus, admitted to the Third People's Hospital of Kunming City on March 6, 2024. Metagenomic RNA sequencing and polymerase chain reaction (PCR) analysis were conducted on the patient's sputum, confirming the H10N3 infection. The patient presented severe pneumonia symptoms such as fever, expectoration, chest tightness, shortness of breath, and cough. Phylogenetic analysis of the Haemagglutinin (HA) and neuraminidase (NA) genes of the virus showed that the virus was most closely related to a case of human infection with the H10N3 subtype of avian influenza virus found in Zhejiang Province, China. Analysis of amino acid mutation sites identified four mutations potentially hazardous to human health. Consequently, this underscores the importance of continuous and vigilant monitoring of the dynamics surrounding the H10N3 subtype of avian influenza virus, utilizing advanced genomic surveillance techniques.

Influenza Virus-Derived CD8 T Cell Epitopes: Implications for the Development of Universal Influenza Vaccines.

The influenza virus poses a global health burden. Currently, an annual vaccine is used to reduce influenza virus-associated morbidity and mortality. Most influenza vaccines have been developed to elicit neutralizing Abs against influenza virus. These Abs primarily target immunodominant epitopes derived from hemagglutinin (HA) or neuraminidase (NA) of the influenza virus incorporated in vaccines. However, HA and NA are highly variable proteins that are prone to antigenic changes, which can reduce vaccine efficacy. Therefore, it is essential to develop universal vaccines that target immunodominant epitopes derived from conserved regions of the influenza virus, enabling cross-protection among different virus variants. The internal proteins of the influenza virus serve as ideal targets for universal vaccines. These internal proteins are presented by MHC class I molecules on Ag-presenting cells, such as dendritic cells, and recognized by CD8 T cells, which elicit CD8 T cell responses, reducing the likelihood of disease and influenza viral spread by inducing virus-infected cell apoptosis. In this review, we highlight the importance of CD8 T cell-mediated immunity against influenza viruses and that of viral epitopes for developing CD8 T cell-based influenza vaccines.

Baicalin reduced injury of and autophagy-related gene expression in RAW264.7 cells infected with H6N6 avian influenza virus.

In the present study, we investigated whether baicalin could reduce the damage caused to RAW264.7 cells following infection with H6N6 avian influenza virus. In addition, we studied the expression of autophagy-related genes. The morphological changes in cells were observed by hematoxylin and eosin (H&E) staining, and the inflammatory factors in the cell supernatant were detected by enzyme-linked immunosorbent assay (ELISA). Transmission electron microscopy (TEM) was used to detect the levels of RAW264.7 autophagosomes, and western blotting and immunofluorescence were used to detect the protein expression of autophagy marker LC3. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the mRNA transcription levels of autophagy key factors. The results showed that different doses of baicalin significantly reduced the H6N6 virus-induced damage of RAW264.7 cells. The contents of interleukin (IL)-1ß, IL-2, IL-6, and tumor necrosis factor (TNF)-α in the cell supernatant significantly decreased. In addition, the protein expression of LC3 and Beclin-1, ATG12, ATG5 the mRNA levels were significantly decreased. This study showed that baicalin can reduce cell damage and affect the H6N6-induced autophagy level of RAW264.7 cells.

Exploring the Efficacy of Peptides and Mimics against Influenza A Virus, Adenovirus, and Murine Norovirus.

The ongoing battle against viral pandemics continues, with the possibility of future outbreaks. The search for effective antiviral compounds that can combat a diverse range of viruses continues to be a focal point of research. This study investigated the efficacy of two natural antimicrobial peptides (AMPs) (lactoferricin and LL-37), two synthetic AMPs (melimine and Mel4), and nine AMP mimics (758, 1091, 1096, 1083, 610, NAPL, 3-BIPL, 4-BIPL, and Sau-22) against influenza A virus strains H1N1 and H3N2, human adenovirus 5 (HAdV-5), and murine norovirus 1 (MNV-1). These compounds were tested using virus pre-treatment, cell pre-treatment, or post-cell entry treatment assays, electron microscopy, and circular dichroism (CD), alongside evaluations of cytotoxicity against the host cells. After virus pre-treatment, the AMP mimics 610 and Sau-22 had relatively low IC50 values for influenza strains H1N1 (2.35 and 6.93 µM, respectively) and H3N2 (3.7 and 5.34 µM, respectively). Conversely, natural and synthetic AMPs were not active against these strains. For the non-enveloped viruses, the AMP Mel4 and mimic 1083 had moderate activity against HAdV-5 (Mel4 IC50 = 47.4 µM; 1083 IC50 = 47.2 µM), whereas all AMPs, but none of the mimics, were active against norovirus (LL-37 IC50 = 4.2 µM; lactoferricin IC50 = 23.18 µM; melimine IC50 = 4.8 µM; Mel4 IC50 = 8.6 µM). Transmission electron microscopy demonstrated that the mimics targeted the outer envelope of influenza viruses, while the AMPs targeted the capsid of non-enveloped viruses. CD showed that Mel4 adopted an α-helical structure in a membrane mimetic environment, but mimic 758 remained unstructured. The diverse activity against different virus groups is probably influenced by charge, hydrophobicity, size, and, in the case of natural and synthetic AMPs, their secondary structure. These findings underscore the potential of peptides and mimics as promising candidates for antiviral therapeutics against both enveloped and non-enveloped viruses.