Potential COVID-19 remedies from repurposed drugs and herbal small RNAs.

To date, SARS-CoV-2 has caused millions of deaths, but the choice of treatment is limited. We previously established a platform for identifying Food and Drug Administration (FDA)-approved repurposed drugs for avian influenza A virus infections that could be used for coronavirus disease 2019 (COVID-19) treatment. In this study, we analyzed blood samples from two cohorts of 63 COVID-19 patients, including 19 patients with severe disease. Among the 39 FDA-approved drugs we identified for COVID-19 therapy in both cohorts, 23 drugs were confirmed by literature mining data, including 14 drugs already under COVID-19 clinical trials and 9 drugs reported for COVID-19 treatments, suggesting the remaining 16 FDA-approved drugs may be candidates for COVID-19 therapy. Additionally, we previously reported that herbal small RNAs (sRNAs) could be effective components in traditional Chinese medicine (TCM) for treating COVID-19. Based on the abundance of sRNAs, we screened the 245 TCMs in the Bencao (herbal) sRNA Atlas that we had previously established, and we found that the top 12 TCMs for COVID-19 treatment was consistent across both cohorts. We validated the efficiency of the top 30 sRNAs from each of the top 3 TCMs for COVID-19 treatment in poly(I:C)-stimulated human non-small cell lung cancer cells (A549 cells). In conclusion, our study recommends potential COVID-19 remedies using FDA-approved repurposed drugs and herbal sRNAs from TCMs.

Oral administration of herbal oligonucleotide drug JGL-sRNA-h7 ameliorates hyperglycemia in db/db mice and beagle dogs.

Type 2 diabetes mellitus is a prevalent metabolic disease, posing a considerable threat to public health. Oligonucleotide drugs have proven to be a promising field of therapy for the diseases. In this study, we reported that a herbal small RNA (sRNA), JGL-sRNA-h7 (B34735529, F1439.L002444.A11), could exhibit potent hypoglycemic effects by targeting glucose-6-phosphatase. Oral administration of sphingosine (d18:1)-JGL-sRNA-h7 bencaosomes ameliorated hyperglycemia and diabetic kidney injury better than metformin in db/db mice. Furthermore, glucose tolerance was also improved in sphingosine (d18:1)-JGL-sRNA-h7 bencaosomes-treated beagle dogs. Our study indicates that JGL-sRNA-h7 could be a promising hypoglycemic oligonucleotide drug.

Ambient atmospheric PM worsens mouse lung injury induced by influenza A virus through lysosomal dysfunction.

BACKGROUND: Particulate matter (PM) air pollution poses a significant risk to respiratory health and is especially linked with various infectious respiratory diseases such as influenza. Our previous studies have shown that H5N1 virus infection could induce alveolar epithelial A549 cell death by enhancing lysosomal dysfunction. This study aims to investigate the mechanisms underlying the effects of PM on influenza virus infections, with a particular focus on lysosomal dysfunction. RESULTS: Here, we showed that PM nanoparticles such as silica and alumina could induce A549 cell death and lysosomal dysfunction, and degradation of lysosomal-associated membrane proteins (LAMPs), which are the most abundant lysosomal membrane proteins. The knockdown of LAMPs with siRNA facilitated cellular entry of both H1N1 and H5N1 influenza viruses. Furthermore, we demonstrated that silica and alumina synergistically increased alveolar epithelial cell death induced by H1N1 and H5N1 influenza viruses by enhancing lysosomal dysfunction via LAMP degradation and promoting viral entry. In vivo, lung injury in the H5N1 virus infection-induced model was exacerbated by pre-exposure to silica, resulting in an increase in the wet/dry ratio and histopathological score. CONCLUSIONS: Our findings reveal the mechanism underlying the synergistic effect of nanoparticles in the early stage of the influenza virus life cycle and may explain the increased number of respiratory patients during periods of air pollution.

Identification of oxidative stress and Toll-like receptor 4 signaling as a key pathway of acute lung injury.

Multiple lung pathogens such as chemical agents, H5N1 avian flu, or SARS cause high lethality due to acute respiratory distress syndrome. Here we report that Toll-like receptor 4 (TLR4) mutant mice display natural resistance to acid-induced acute lung injury (ALI). We show that TLR4-TRIF-TRAF6 signaling is a key disease pathway that controls the severity of ALI. The oxidized phospholipid (OxPL) OxPAPC was identified to induce lung injury and cytokine production by lung macrophages via TLR4-TRIF. We observed OxPL production in the lungs of humans and animals infected with SARS, Anthrax, or H5N1. Pulmonary challenge with an inactivated H5N1 avian influenza virus rapidly induces ALI and OxPL formation in mice. Loss of TLR4 or TRIF expression protects mice from H5N1-induced ALI. Moreover, deletion of ncf1, which controls ROS production, improves the severity of H5N1-mediated ALI. Our data identify oxidative stress and innate immunity as key lung injury pathways that control the severity of ALI.

CLIP-Driven Prototype Network for Few-Shot Semantic Segmentation.

Recent research has shown that visual-text pretrained models perform well in traditional vision tasks. CLIP, as the most influential work, has garnered significant attention from researchers. Thanks to its excellent visual representation capabilities, many recent studies have used CLIP for pixel-level tasks. We explore the potential abilities of CLIP in the field of few-shot segmentation. The current mainstream approach is to utilize support and query features to generate class prototypes and then use the prototype features to match image features. We propose a new method that utilizes CLIP to extract text features for a specific class. These text features are then used as training samples to participate in the model's training process. The addition of text features enables model to extract features that contain richer semantic information, thus making it easier to capture potential class information. To better match the query image features, we also propose a new prototype generation method that incorporates multi-modal fusion features of text and images in the prototype generation process. Adaptive query prototypes were generated by combining foreground and background information from the images with the multi-modal support prototype, thereby allowing for a better matching of image features and improved segmentation accuracy. We provide a new perspective to the task of few-shot segmentation in multi-modal scenarios. Experiments demonstrate that our proposed method achieves excellent results on two common datasets, PASCAL-5i and COCO-20i.

A Single-Enantiomer Emitter Enabled Superstructural Helix Inversion for Upconverting and Downshifting Luminescence with Bidirectional Circular Polarization.

The helical twisting tendency of liquid crystals (LCs) is generally governed by the inherent configuration of the chiral emitter. Here, we introduce the multistage inversion of supramolecular chirality as well as circularly polarized luminescence (CPL) by manipulating the ratio of single enantiomeric emitters (R-PCP) to LC monomers (5CB). Increasing the content of R-PCP from 1 wt % to 3 wt % inverted the helix of LCs from left-handed to right-handed, accompanying a CPL sign changed from positive to negative. The biaxiality of chiral emitters, as well as the steric effect of chiral-chiral and chiral-achiral interaction, were identified as the reasons for helical sense inversion. Due to the strong helical twisting power, 4 wt % R-PCP drove the photonic band gap (PBG) of chiral LCs to match up with their emission range, leading to an inversion of the CPL again with a high dissymmetry factor (≈1.2). Directly adjusting the PBG using chiral emitters is seldom achieved in cholesteric LCs. On this basis, an achiral sensitizer PtTPBP was assembled into the helical superstructure. The generation of triplet-triplet annihilation-induced upconverted CPL from R-PCP and the downshifting CPL from PtTPBP with opposite rotation was achieved in a single chiral LC system by tuning the position of the PBG.

Identification of amitriptyline HCl, flavin adenine dinucleotide, azacitidine and calcitriol as repurposing drugs for influenza A H5N1 virus-induced lung injury.

Infection with avian influenza A H5N1 virus results in acute lung injury (ALI) and has a high mortality rate (52.79%) because there are limited therapies available for treatment. Drug repositioning is an economical approach to drug discovery. We developed a method for drug repositioning based on high-throughput RNA sequencing and identified several drugs as potential treatments for avian influenza A H5N1 virus. Using high-throughput RNA sequencing, we identified a total of 1,233 genes differentially expressed in A549 cells upon H5N1 virus infection. Among these candidate genes, 79 drug targets (corresponding to 59 approved drugs) overlapped with the DrugBank target database. Twenty-two of the 41 commercially available small-molecule drugs reduced H5N1-mediated cell death in cultured A549 cells, and fifteen drugs that protected A549 cells when administered both pre- and post-infection were tested in an H5N1-infection mouse model. The results showed significant alleviation of acute lung injury by amitriptyline HCl (an antidepressant drug), flavin adenine dinucleotide (FAD; an ophthalmic agent for vitamin B2 deficiency), azacitidine (an anti-neoplastic drug) and calcitriol (an active form of vitamin D). All four agents significantly reduced the infiltrating cell count and decreased the lung injury score in H5N1 virus-infected mice based on lung histopathology, significantly improved mouse lung edema by reducing the wet-to-dry weight ratio of lung tissue and significantly improved the survival of H5N1 virus-infected mice. This study not only identifies novel potential therapies for influenza H5N1 virus-induced lung injury but also provides a highly effective and economical screening method for repurposing drugs that may be generalizable for the prevention and therapy of other diseases.

Herbal inhibitors of SARS-CoV-2 Mpro effectively ameliorate acute lung injury in mice.

Coronavirus disease 2019, a newly emerging serious infectious disease, has spread worldwide. To date, effective drugs against the disease are limited. Traditional Chinese medicine was commonly used in treating COVID-19 patients in China. Here we tried to identify herbal effective lipid compounds from the lipid library of 92 heat-clearing and detoxication Chinese herbs. Through virtual screening, enzymatic activity and inhibition assays, and surface plasmon resonance tests, we identified lipid compounds targeting the main protease (Mpro ) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and verified their functions. Here, we found that natural lipid compounds LPC (14:0/0:0) and LPC (16:0/0:0) could target SARS-CoV-2 Mpro , recover cell death induced by SARS-CoV-2, and ameliorate acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) induced by bacterial lipopolysaccharides and virus poly (I:C) mimics in vivo and in vitro. Our results suggest that LPC (14:0/0:0) and LPC (16:0/0:0) might be potential pan remedy against ARDS.

Nuclear translocation of RIG-I promotes cellular apoptosis.

Cell death is important in the elimination of damaged cells such as virus-infected cells and also is closely involved in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). The retinoic acid-inducible gene-I (RIG-I), one cytosolic RNA innate sensor, can trigger antiviral innate response by inducing production of type I interferons (IFN-I). However, the function of RIG-I, once translocated from cytoplasm to nucleus at the late stage of viral infection when IFN-I production is almost terminated, remains poorly understood. Here, we reported that RIG-I is accumulated in the nucleus of macrophages and fibroblasts after virus infection, and nuclear RIG-I is present in peripheral blood mononuclear cells (PBMCs) from SLE patients. We found that nuclear RIG-I interacts with the first 20 amino acids of apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) and attenuates the anti-apoptotic properties of APEX1, therefore promoting apoptosis of virus-infected cells to suppress viral infection through an IFN-I-independent way at the late stage of viral infection. Together, our findings reveal a non-canonical role of nuclear RIG-I in the induction of cellular apoptosis, besides its activation of IFN-I expression as the cytosolic innate sensor. This study provides new insight to the regulation of infection, IFN-I and autoimmune diseases by nuclear RIG-I-APEX1 interaction.

Associations between ambient temperature and adult asthma hospitalizations in Beijing, China: a time-stratified case-crossover study.

BACKGROUND: Studies on the associations between ambient temperature and asthma hospitalizations are limited, and the results are controversial. We aimed to assess the short-term effects of ambient temperature on the risk of asthma hospitalizations and quantify the hospitalization burdens of asthma attributable to non-optimal temperature in adults in Beijing, China. METHODS: We collected daily asthma hospitalizations, meteorological factors and air quality data in Beijing from 2012 to 2015. We applied a time-stratified case-crossover design and fitted a distributed lag non-linear model with a conditional quasi-Poisson regression to explore the association between ambient temperature and adult asthma hospitalizations. The effect modifications of these associations by gender and age were assessed by stratified analyses. We also computed the attributable fractions and numbers with 95% empirical confidence intervals (eCI) of asthma hospitalizations due to extreme and moderate temperatures. RESULTS: From 2012 to 2015, we identified a total of 18,500 hospitalizations for asthma among adult residents in Beijing, China. Compared with the optimal temperature (22 °C), the cumulative relative risk (CRR) over lag 0-30 days was 2.32 with a 95% confidence interval (CI) of 1.57-3.42 for extreme cold corresponding to the 2.5th percentile (- 6.5 °C) of temperature distribution and 2.04 (95% CI 1.52-2.74) for extreme heat corresponding to the 97.5th percentile (29 °C) of temperature distribution. 29.1% (95% eCI 17.5-38.0%) of adult asthma hospitalizations was attributable to non-optimum temperatures. Moderate cold temperatures yielded most of the burdens, with an attributable fraction of 20.3% (95% eCI 9.1-28.7%). The temperature-related risks of asthma hospitalizations were more prominent in females and younger people (19-64 years old). CONCLUSIONS: There was a U-shaped association between ambient temperature and the risk of adult asthma hospitalizations in Beijing, China. Females and younger patients were more vulnerable to the effects of non-optimum temperatures. Most of the burden was attributable to moderate cold. Our findings may uncover the potential impact of climate changes on asthma exacerbations.

18:0 Lyso PC, a natural product with potential PPAR-γ agonistic activity, plays hypoglycemic effect with lower liver toxicity and cardiotoxicity in db/db mice.

Rosiglitazone, a specific agonist of peroxisome proliferator-activated receptor-γ (PPAR-γ), displays a robust hypoglycemic action in patients with type 2 diabetes mellitus (T2DM) and elicits serious adverse reactions, especially hepatotoxicity and cardiotoxicity. Here, we aims to find a new natural PPAR-γ agonist with less adverse reactions than rosiglitazone in db/db mice. The method of virtual screening was used to identify a PPAR-γ agonist 18:0 Lyso PC from an in-house natural product library. We verified its pharmacological effects and adverse reactions comparing with rosiglitazone in vivo and in vitro. 18:0 Lyso PC exhibited pharmacological effects similar to those of rosiglitazone in db/db mice. Moreover, 18:0 Lyso PC showed a lower extent of liver injury and cardiotoxicity in db/db mice. The mechanism, by which this natural compound alleviates metabolic syndrome, involves a reduction in fatty acid synthesis mediated by activation of the phosphorylation of adenosine 5'-monophosphate (AMP)-activated protein kinase-alpha (AMPKα) and acetyl-CoA carboxylase (ACC) and an increase expression of uncoupled protein 1 (UCP1) and PPAR-γ coactivator-1 alpha (PGC1-α). 18:0 Lyso PC, a natural compound, can show a similar hypoglycemic effect to rosiglitazone by activating PPAR-γ, while eliciting markedly fewer adverse reactions than rosiglitazone.

Plasma IP-10 and MCP-3 levels are highly associated with disease severity and predict the progression of COVID-19.

BACKGROUND: The outbreak of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 was first reported in Wuhan, December 2019, and continuously poses a serious threat to public health, highlighting the urgent need of identifying biomarkers for disease severity and progression. OBJECTIVE: We sought to identify biomarkers for disease severity and progression of COVID-19. METHODS: Forty-eight cytokines in the plasma samples from 50 COVID-19 cases including 11 critically ill, 25 severe, and 14 moderate patients were measured and analyzed in combination with clinical data. RESULTS: Levels of 14 cytokines were found to be significantly elevated in COVID-19 cases and showed different expression profiles in patients with different disease severity. Moreover, expression levels of IFN-γ-induced protein 10, monocyte chemotactic protein-3, hepatocyte growth factor, monokine-induced gamma IFN, and macrophage inflammatory protein 1 alpha, which were shown to be highly associated with disease severity during disease progression, were remarkably higher in critically ill patients, followed by severe and then the moderate patients. Serial detection of the 5 cytokines in 16 cases showed that continuously high levels were associated with deteriorated progression of disease and fatal outcome. Furthermore, IFN-γ-induced protein 10 and monocyte chemotactic protein-3 were excellent predictors for the progression of COVID-19, and the combination of the 2 cytokines showed the biggest area under the curve of the receiver-operating characteristics calculations with a value of 0.99. CONCLUSIONS: In this study, we report biomarkers that are highly associated with disease severity and progression of COVID-19. These findings add to our understanding of the immunopathologic mechanisms of severe acute respiratory syndrome coronavirus 2 infection, and provide potential therapeutic targets and strategies.

Separation of phenolics from peony flowers and their inhibitory activities and action mechanism on bacterial biofilm.

Separation and enrichment of phenolics from peony flowers were performed to improve the anti-biofilm and antibacterial activities for the first time. Through several times of separation, the purity of phenolics components increased significantly, and the anti-biofilm and antibacterial activities of phenolics components against E. coli and S. aureus were also significantly improved. Finally, the phenolics of peony flowers in the eluent of silica gel column chromatography (PPF-ESGCC) were found to exhibit the highest anti-biofilm and antibacterial activities. The inhibition rates of PPF-ESGCC on biofilms of E. coli and S. aureus were 77.93%, and 87.03% respectively, at a very low concentration (1/2 MIC, 0.235 mg/mL). It was found that the biofilm inhibition was achieved by inhibiting their swimming, swarming, twitching motilities, exopolysaccharide (EPS) production, and quorum sensing (QS). Moreover, there was a positive dose-dependent relationship (r = 0.75 to 1) between the inhibition rates and concentrations of PPF-ESGCC during the critical biofilm-formation stage (1-3 days). Chemical composition analysis showed the PPF-ESGCC comprised of gallic acid, kaempferol-7-O-glucoside, and apigenin-7-O-glucoside. In conclusion, PPF-ESGCC exhibited strong inhibitory effect on biofilm formation and gallic acid, kaempferol-7-O-glucoside, and apigenin-7-O-glucoside might play a crucial role in inhibiting biofilm formation. Meanwhile, this study indicated that PPF-ESGCC, a new natural QS inhibitor and biofilm inhibitor, could be used as a novel intervention strategy to enhance the safety and quality of food.

Highly Sensitive Flow Sensor Based on Flexible Dual-Layer Heating Structures.

Hot film sensors detect the flow shear stress based on the forced convection heat transfer to the fluid. Current hot film sensors have been significantly hindered by the relatively low sensitivity due to the massive heat conduction to the substrate. This paper describes the design, fabrication, simulation, and testing of a novel flow sensor with dual-layer hot film structures. More specifically, the heat conduction was insulated from the sensing heater to the substrate by controlling both sensing and guarding heaters working at the same temperature, resulting in a higher sensitivity. The experiment and simulation results showed that the sensitivity of the dual-layer hot film sensor was significantly improved in comparison to the single-layer sensor. Additionally, the dual-layer sensor was designed and fabricated in an integrated, flexible, and miniaturized manner. Its small size makes it an excellent candidate for flow detection.

Clinical and Immunological Characteristics of Human Infections With H5N6 Avian Influenza Virus.

BACKGROUND: H5N6 avian influenza virus (AIV) has caused sporadic, recurring outbreaks in China and Southeast Asia since 2013, with 19 human infections and 13 deaths. Seventeen of these infections occurred since December 2015, indicating a recent rise in the frequency of H5N6 cases. METHODS: To assess the relative threat of H5N6 virus to humans, we summarized and compared clinical data from patients infected with H5N6 (n = 19) against data from 2 subtypes of major public health concern, H5N1 (n = 53) and H7N9 (n = 160). To assess immune responses indicative of prognosis, we compared concentrations of serum cytokines/chemokines in patients infected with H5N6, H5N1, H7N9, and 2009 pandemic H1N1 and characterized specific immune responses from 1 surviving and 2 nonsurviving H5N6 patients. RESULTS: H5N6 patients were found to have higher incidences of lymphopenia and elevated alanine aminotransferase and lactate dehydrogenase levels compared with H5N1 and H7N9 patients. Hypercytokinemia was detected at substantially higher frequencies from H5N6 patients compared to those infected with other AIV subtypes. Evaluation of adaptive immunity showed that both humoral and cellular responses could be detected in the H5N6-infected survivor, but cellular responses were absent in the nonsurvivors. In addition, the surviving patient had lower concentrations of both pro- and anti-inflammatory cytokines/chemokines compared to the nonsurvivors. CONCLUSIONS: Our results support that H5N6 virus could potentially be a major public health threat, and suggest it is possible that the earlier acquisition of cellular immunity and lower concentrations of cytokines/chemokines contributed to survival in our patient. Analysis of more patient samples will be needed to draw concrete conclusions.

Probing the influence of SIBLING proteins on collagen-I fibrillogenesis and denaturation.

Bone tissue is comprised of collagen, non-collagenous proteins, and hydroxyapatite and the SIBLING (small integrin binding, N-linked glycoprotein) family of proteins is the primary group of non-collagenous proteins. By replicating the native interactions between collagen and the SIBLING proteins at the interface of an implant, it is believed that a bone scaffold will more easily integrate with the surrounding tissue. In this work, bone sialoprotein, osteopontin (OPN), dentin sialoprotein (DSP), dentin phosphoprotein (DPP), C-terminal fragment of dentin matrix protein 1 (DMP1-C), and proteoglycan versions of DSP (DSP-PG) and DMP1 (DMP1-PG) were tested individually to determine their roles in collagen fibrillogenesis and the prevention of denaturation. It was shown that DSP and DPP slowed down fibrillogenesis, while other SIBLINGs had limited impact. In addition, the denaturation time was faster in the presence of DSP and OPN, indicating a negative impact. The role of calcium ions in these processes was also investigated. The presence of calcium ions sped up fibrillogenesis in all scenarios tested, but it had a negative impact by reducing the extent. Calcium also sped up the denaturation in most cases, with the exception of DMP1-C and DSP where the opposite was seen. Calcium had a similar effect on the proteoglycan variants in the fibrillogenesis process, but had no impact on the denaturation process in the presence of these two. It is believed that incorporating DMP1-C or DSP on the surface of a bone implant may improve the collagen interactions with the implant, thereby facilitating improved osteointegration.

FAT10 Is Critical in Influenza A Virus Replication by Inhibiting Type I IFN.

The H5N1 avian influenza virus causes severe disease and high mortality, making it a major public health concern worldwide. The virus uses the host cellular machinery for several steps of its life cycle. In this report, we observed overexpression of the ubiquitin-like protein FAT10 following live H5N1 virus infection in BALB/c mice and in the human respiratory epithelial cell lines A549 and BEAS-2B. Further experiments demonstrated that FAT10 increased H5N1 virus replication and decreased the viability of infected cells. Total RNA extracted from H5N1 virus-infected cells, but not other H5N1 viral components, upregulated FAT10, and this process was mediated by the retinoic acid-induced protein I-NF-κB signaling pathway. FAT10 knockdown in A549 cells upregulated type I IFN mRNA expression and enhanced STAT1 phosphorylation during live H5N1 virus infection. Taken together, our data suggest that FAT10 was upregulated via retinoic acid-induced protein I and NF-κB during H5N1 avian influenza virus infection. And the upregulated FAT10 promoted H5N1 viral replication by inhibiting type I IFN.

In Situ Observation of Dynamic Wetting Transition in Re-Entrant Microstructures.

Re-entrant microstructures exhibit excellent wetting stability under different pressure levels, but the underlying mechanism determined by wetting transition behavior at the microscale level remains unclear. We propose the "wetting chip" method for in situ assessment of the dynamic behavior of wetting transition in re-entrant microstructures. High sag and transverse depinning were observed in re-entrant microstructures. Analysis indicated that high sag and transverse depinning mainly influenced the stability of the structures. The threshold pressure and longevity of wetting transition were predicted and experimentally verified. The design criteria of wetting stability, including small geometry design, hydrophobic material selection, and sidewall condition, were also presented. The proposed method and model can be applied to different shapes and geometry microstructures to elucidate wetting stability.

Nosocomial Co-Transmission of Avian Influenza A(H7N9) and A(H1N1)pdm09 Viruses between 2 Patients with Hematologic Disorders.

A nosocomial cluster induced by co-infections with avian influenza A(H7N9) and A(H1N1)pdm09 (pH1N1) viruses occurred in 2 patients at a hospital in Zhejiang Province, China, in January 2014. The index case-patient was a 57-year-old man with chronic lymphocytic leukemia who had been occupationally exposed to poultry. He had co-infection with H7N9 and pH1N1 viruses. A 71-year-old man with polycythemia vera who was in the same ward as the index case-patient for 6 days acquired infection with H7N9 and pH1N1 viruses. The incubation period for the second case-patient was estimated to be <4 days. Both case-patients died of multiple organ failure. Virus genetic sequences from the 2 case-patients were identical. Of 103 close contacts, none had acute respiratory symptoms; all were negative for H7N9 virus. Serum samples from both case-patients demonstrated strong proinflammatory cytokine secretion but incompetent protective immune responses. These findings strongly suggest limited nosocomial co-transmission of H7N9 and pH1N1 viruses from 1 immunocompromised patient to another.

Neuraminidase of Influenza A Virus Binds Lysosome-Associated Membrane Proteins Directly and Induces Lysosome Rupture.

UNLABELLED: As a recycling center, lysosomes are filled with numerous acid hydrolase enzymes that break down waste materials and invading pathogens. Recently, lysosomal cell death has been defined as "lysosomal membrane permeabilization and the consequent leakage of lysosome contents into cytosol." Here, we show that the neuraminidase (NA) of H5N1 influenza A virus markedly deglycosylates and degrades lysosome-associated membrane proteins (LAMPs; the most abundant membrane proteins of lysosome), which induces lysosomal rupture, and finally leads to cell death of alveolar epithelial carcinoma A549 cells and human tracheal epithelial cells. The NA inhibitors peramivir and zanamivir could effectively block the deglycosylation of LAMPs, inhibit the virus cell entry, and prevent cell death induced by the H5N1 influenza virus. The NA of seasonal H1N1 virus, however, does not share these characteristics. Our findings not only reveal a novel role of NA in the early stage of the H5N1 influenza virus life cycle but also elucidate the molecular mechanism of lysosomal rupture crucial for influenza virus induced cell death. IMPORTANCE: The integrity of lysosomes is vital for maintaining cell homeostasis, cellular defense and clearance of invading pathogens. This study shows that the H5N1 influenza virus could induce lysosomal rupture through deglycosylating lysosome-associated membrane proteins (LAMPs) mediated by the neuraminidase activity of NA protein. NA inhibitors such as peramivir and zanamivir could inhibit the deglycosylation of LAMPs and protect lysosomes, which also further interferes with the H5N1 influenza virus infection at early stage of life cycle. This work is significant because it presents new concepts for NA's function, as well as for influenza inhibitors' mechanism of action, and could partially explain the high mortality and high viral load after H5N1 virus infection in human beings and why NA inhibitors have more potent therapeutic effects for lethal avian influenza virus infections at early stage.