BATF regulates progenitor to cytolytic effector CD8+ T cell transition during chronic viral infection.

During chronic viral infection, CD8+ T cells develop into three major phenotypically and functionally distinct subsets: Ly108+TCF-1+ progenitors, Ly108-CX3CR1- terminally exhausted cells and the recently identified CX3CR1+ cytotoxic effector cells. Nevertheless, how CX3CR1+ effector cell differentiation is transcriptionally and epigenetically regulated remains elusive. Here, we identify distinct gene regulatory networks and epigenetic landscapes underpinning the formation of these subsets. Notably, our data demonstrate that CX3CR1+ effector cells bear a striking similarity to short-lived effector cells during acute infection. Genetic deletion of Tbx21 significantly diminished formation of the CX3CR1+ subset. Importantly, we further identify a previously unappreciated role for the transcription factor BATF in maintaining a permissive chromatin structure that allows the transition from TCF-1+ progenitors to CX3CR1+ effector cells. BATF directly bound to regulatory regions near Tbx21 and Klf2, modulating their enhancer accessibility to facilitate the transition. These mechanistic insights can potentially be harnessed to overcome T cell exhaustion during chronic infection and cancer.

CD4+ T Cell Help Is Required for the Formation of a Cytolytic CD8+ T Cell Subset that Protects against Chronic Infection and Cancer.

Although CD4+ T cell "help" is crucial to sustain antiviral immunity, the mechanisms by which CD4+ T cells regulate CD8+ T cell differentiation during chronic infection remain elusive. Here, using single-cell RNA sequencing, we show that CD8+ T cells responding to chronic infection were more heterogeneous than previously appreciated. Importantly, our findings uncovered the formation of a CX3CR1-expressing CD8+ T cell subset that exhibited potent cytolytic function and was required for viral control. Notably, our data further demonstrate that formation of this cytotoxic subset was critically dependent on CD4+ T cell help via interleukin-21 (IL-21) and that exploitation of this developmental pathway could be used therapeutically to enhance the killer function of CD8+ T cells infiltrated into the tumor. These findings uncover additional molecular mechanisms of how "CD4+ T cell help" regulates CD8+ T cell differentiation during persistent infection and have implications toward optimizing the generation of protective CD8+ T cells in immunotherapy.

Glycogen synthase kinase-3ß: A multifaceted player in ischemia-reperfusion injury and its therapeutic prospects.

Ischemia-reperfusion injury (IRI) results in irreversible metabolic dysfunction and structural damage to tissues or organs, posing a formidable challenge in the field of organ implantation, cardiothoracic surgery, and general surgery. Glycogen synthase kinase-3ß (GSK-3ß) a multifunctional serine/threonine kinase, is involved in a variety of biological processes, including cell proliferation, apoptosis, and immune response. Phosphorylation of its tyrosine 216 and serine 9 sites positively and negatively regulates the activation and inactivation of the enzyme. Significantly, inhibition or inactivation of GSK-3ß provides protection against IRI, making it a viable target for drug development. Though numerous GSK-3ß inhibitors have been identified to date, the development of therapeutic treatments remains a considerable distance away. In light of this, this review summarizes the complicated network of GSK-3ß roles in IRI. First, we provide an overview of GSK-3ß's basic background. Subsequently, we briefly review the pathological mechanisms of GSK-3ß in accelerating IRI, and highlight the latest progress of GSK-3ß in multiorgan IRI, encompassing heart, brain, kidney, liver, and intestine. Finally, we discuss the current development of GSK-3ß inhibitors in various organ IRI, offering a thorough and insightful reference for GSK-3ß as a potential target for future IRI therapy.

TNIK in disease: from molecular insights to therapeutic prospects.

TRAF2 and NCK interacting kinase (TNIK), a critical interacting protein kinase, is currently receiving wide attention. TNIK is found in various human body organs and tissues and participates in cell motility, proliferation, and differentiation. On the one hand, its aberrant expression is related to the onset and progression of numerous malignant tumors. On the other hand, TNIK is important in neuronal growth, proliferation, differentiation, and synaptic formation. Thus, the novel therapeutic strategies for targeting TNIK offer a promising direction for cancer, neurological or psychotic disorders. Here, we briefly summarized the biological information of TNIK, reviewed the role and regulatory mechanism in cancer and neuropsychiatric diseases, and introduced the research progress of inhibitors targeting TNIK. Taken together, this review hopes to contribute to the in-depth understanding of the function and regulatory mechanism of TNIK, which is of great significance for revealing the role of TNIK in the occurrence and treatment of diseases.

Extracellular vesicles derived from "serum and glucose" deprived HUCMSCs promoted skin wound healing through enhanced angiogenesis.

Extracellular vesicles (EVs) produced from MSCs were currently considered as a novel therapeutic agent for skin tissue regeneration and repair. Preconditioning stem cells may activate more molecular pathways and release more bioactive agents. In this study, we obtained EVs from normal (N-EVs) and serum- and glucose-deprived (SGD-EVs) human umbilical cord mesenchymal stem cells (HUCMSCs), and showed that SGD-EVs promoted the migration, proliferation, and tube formation of HUVECs in vitro. In vivo experiments utilizing a rat model show that both N-EVs and SGD-EVs boosted angiogenesis of skin defects and accelerated skin wound healing, while treating wounds with SGD-EVs led to faster skin healing and enhanced angiogenesis. miRNA sequencing showed that miR-29a-3p was abundant in SGD-EVs, and overexpressing miR-29a-3p enhanced the angiogenic ability of HUVECs, while inhibiting miR-29a-3p presented the opposite effect. Further studies demonstrated that miR-29a-3p directly targeted CTNNBIP1, which mediated angiogenesis of HUCMSCs-derived EVs through inhibiting CTNNBIP1 to activate Wnt/ß-catenin signaling pathway. Taken together, these findings suggested that SGD-EVs promote angiogenesis via transferring miR-29a-3p, and activation of Wnt/ß-catenin signaling pathway played a crucial role in SGD-EVs-induced VEGFA production during wound angiogenesis. Our results offered a new avenue for modifying EVs to enhance tissue angiogenesis and augment its role in skin repair.

Fluorescent probe based on GO/g-C3N4-PEG@Cu NPs/MIP for the detection of dopamine in banana.

Graphene oxide (GO) and copper nanoparticles (Cu NPs) were incorporated to modulate and enhance the fluorescence properties of pegylated graphite phase carbon nitride (g-C3N4-PEG). Combined with the specific recognition capability of a molecular imprinted polymer (MIP), a highly sensitive and selective fluorescent molecular imprinted probe for dopamine detection was developed. The fluorescent g-C3N4-PEG was synthesized from melamine and modified with GO and Cu NPs to obtain GO/g-C3N4-PEG@Cu NPs. Subsequently, MIP was prepared on the surface of GO/g-C3N4-PEG@Cu NPs using dopamine as the template molecule. Upon elution of the template molecule, a dopamine-specific GO/g-C3N4-PEG@Cu NPs/MIP fluorescence probe was obtained. The fluorescence intensity of the probe was quenched through the adsorption of different concentrations of dopamine by the MIP, thus establishing a novel method for the detection of dopamine. The linear range of dopamine detection was from 5 × 10-11 to 6 × 10-8 mol L-1, with a detection limit of 2.32 × 10-11 mol L-1. The sensor was utilised for the detection of dopamine in bananas, achieving a spiked recovery rate between 90.3% and 101.3%. These results demonstrate that the fluorescence molecular imprinted sensor developed in this study offers a highly sensitive approach for dopamine detection in bananas.

Genome-wide association analysis of kernel nutritional quality in two natural maize populations.

As one of the three staple crops, nutritional traits in maize are important for human and animal nutrition. Grain quality-related traits are closely related to grain commercial value. Understanding the genetic basis of quality-related traits in maize would be helpful for breeding high-quality maize varieties. In this study, two association panels (AM122 and AM180) were subjected to genome-wide association analysis of grain quality-related traits, including protein content, oil content, starch content, and fiber content. In total, 98 SNPs (P < 1 × 10-4) were identified to be significantly associated with these four grain quality-related traits. By integrating two sets of public transcriptome data, 31 genes located in 200 kb regions flanking the associated SNP showed high expression during kernel development and were differentially expressed in two maize inbred lines, KA225 and KB035, with significantly different quality. These genes might regulate maize grain quality by participating in plant hormone processes, autophagy processes, and others. All these results could provide important reference information for breeding high­quality maize varieties. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01360-w.

Radical deuteration.

Deuterated chemicals are becoming irreplaceable in pharmaceutical engineering, material science and synthetic chemistry. Many excellent reviews have discussed acid/base-dependent or metal-catalyzed deuteration reactions, but radical deuterations have been discussed less. With the development of radical chemistry, there has been a rapid growth in radical deuterium-labelling technology. Diverse mild, cheap and efficient strategies for deuterium atom installation have been reported, and this review summarizes the recent achievements of radical deuteration classified by the reaction types.

Interferon Inducer IFI35 regulates RIG-I-mediated innate antiviral response through mutual antagonism with Influenza protein NS1.

Interferon-stimulated genes (ISGs) create multiple lines of defense against viral infection. Here we show that interferon induced protein 35 (IFI35) inhibits swine (H3N2) influenza virus replication by directly interacting with the viral protein NS1. IFI35 binds more preferentially to the effector domain of NS1 (128-207aa) than to the viral RNA sensor RIG-I. This promotes mutual antagonism between IFI35 and NS1, and frees RIG-I from IFI35-mediated K48-linked ubiquitination and degradation. However, IFI35 does not interact with the NS1 encoded by avian (H7N9) influenza virus, resulting in IFI35 playing an opposite virus enabling role during highly pathogenic H7N9 virus infection. Notably, replacing the 128-207aa region of NS1-H7N9 with the corresponding region of NS1-H3N2 results in the chimeric NS1 acquiring the ability to bind to and mutually antagonize IFI35. IFI35 deficient mice accordingly exhibit more resistance to lethal H7N9 infection than their wild-type control exhibit. Our data uncover a novel mechanism by which IFI35 regulates RIG-I-mediated anti-viral immunity through mutual antagonism with influenza protein NS1.IMPORTANCEIAV infection poses a global health threat, and is among the most common contagious pathogens to cause severe respiratory infections in humans and animals. ISGs play a key role in host defense against IAV infection. In line with others, we show IFI35-mediated ubiquitination of RIG-I to be involved in innate immunity. Moreover, we define a novel role of IFI35 in regulating the type I IFN pathway during IAV infection. We found that IFI35 regulates RIG-I mediated antiviral signaling by interacting with IAV-NS1. H3N2 NS1, but notably not H7N9 NS1, interacts with IFI35 and efficiently suppresses IFI35-dependent ubiquitination of RIG-I. IFI35 deficiency protected mice from H7N9 virus infection. Therefore, manipulation of the IFI35-NS1 provides a new approach for the development of anti-IAV treatments.

Gold-Catalyzed Divergent Ring-Opening Rearrangement of Cyclopropenes Enabled by Dichotomous Gold-Carbenes.

The gold-catalyzed ring-opening rearrangement of cyclopropenes affords an efficient route to either polysubstituted naphthols or aryl-substituted furans. Owing to the unique dichotomy of gold-carbenes, this protocol provides a switchable reaction selectivity between naphthols and furans enabled by the use of TFP-Au(MeCN)SbF6 (tri(2-furyl) phosphine) or PNP(AuNTf2 )2 (bis(diphenylphosphino)(isopropyl) amine) as catalysts respectively. It is proposed that the gold-carbene intermediate might be involved in the cyclopropene→naphthol rearrangement while the gold-carbocation is more likely to be involved in the cyclopropene→furan rearrangement.

Nickel-catalyzed Thioester Transfer Reaction with sp2-Hybridized Electrophiles.

We report a thioacylation transfer reaction based on nickel-catalyzed C-C bond cleavage of thioesters with sp2-hybridized electrophiles. Aryl bromides, iodides, and alkenyl triflates can participate in thioester transfer reaction of aryl thioesters, affording a wide range of structurally diverse new thioesters in yields of up to 98% under mild reaction conditions. With this protocol, it is possible to construct alkenyl thioesters from the corresponding ketones through the generation of alkenyl triflates.

Comparison of three sedation models for same-day painless bidirectional endoscopy: A multicenter randomized controlled trial.

BACKGROUND AND AIM: We investigated the most beneficial propofol sedation model for same-day painless bidirectional endoscopy (BDE). METHODS: Asymptomatic participants scheduled for same-day painless BDE examination from October 2020 to September 2021 were randomized to three groups: sedated esophagogastroduodenoscopy followed by unsedated colonoscopy (Group A); sedated esophagogastroduodenoscopy followed by sedated colonoscopy (Group B); and sedated esophagogastroduodenoscopy followed by sedated insertion colonoscopy (Group C). Patient discomfort, colonoscopy performance, doses of propofol, cardiovascular stress, anesthesia resuscitation, and sedation-related adverse events were evaluated. RESULTS: A total of 3200 participants were analyzed. Baseline demographics, patient discomfort, cecal intubation rate, adenoma detection rate and sedation-related adverse events were similar in the three groups. Propofol dose was the lowest in Group A (137.65 ± 36.865 mg) compared with Group B (177.71 ± 40.112 mg, P < 0.05) and Group C (161.63 ± 31.789 mg, P < 0.05). Decline in vital signs was most obvious in Group B during the procedure (P < 0.05). Recovery time was the shortest in Group A (5.01 ± 1.404 min) compared with Group B (9.51 ± 2.870 min, P < 0.05) and Group C (5.83 ± 2.594 min, P < 0.05); discharge time was the shortest in Group A (3.53 ± 1.685 min) compared with Group B (11.29 ± 5.172 min, P < 0.05) and Group C (6.47 ± 2.338 min, P < 0.05). Adenomas per positive patient of Group A (2.29 ± 1.055) and Group C (2.28 ± 0.931) were more than that in Group B (2.11 ± 0.946, P < 0.05). CONCLUSIONS: Sedated esophagogastroduodenoscopy followed by unsedated colonoscopy is the superior model for same-day painless BDE with the benefits of satisfactory patient comfort, reduced sedation dose, less cardiovascular stress, faster recovery, shorter discharge time and high colonoscopy quality.

Isolated Indium Hydrides in CHA Zeolites: Speciation and Catalysis for Nonoxidative Dehydrogenation of Ethane.

The study of the formation, characterization, and functionality of isolated surface hydrides on solid materials is a formidable task because of the complexity of solid surfaces and the difficulty of analyzing structures in solids. Herein, we found the formation of indium (In) hydride species supported by CHA zeolites. The In hydrides were formed by treatment of an In-exchanged CHA zeolite (In-CHA) with H2 at high temperatures (>773 K). In situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations revealed that an [InH2]+ ion on a framework anionic site is a plausible structure. In-CHA exhibited high selectivity and durable catalytic activity for the nonoxidative dehydrogenation of ethane for at least 90 h. Kinetic and in situ spectroscopic studies as well as transition state (TS) calculations suggested that [InH2]+ ions serve as catalytically active sites for selective dehydrogenation using In-CHA.

Speckle tracking for predicting outcomes of balloon pulmonary angioplasty in patients with chronic thromboembolic pulmonary hypertension.

BACKGROUND: Right ventricular (RV) function is a prognostic marker of chronic thromboembolic pulmonary hypertension (CTEPH). We used two-dimensional (2D) speckle-tracking echocardiography (STE) to evaluate the therapeutic effects of balloon pulmonary angioplasty (BPA) in CTEPH patients. METHODS: A total of 46 CTEPH patients who underwent 2D STE before and after BPA were enrolled in this retrospective study. The following RV functional parameters were measured: tricuspid annular plane systolic excursion (TAPSE), right ventricular fractional area change (RVFAC), RV index of myocardial performance (RIMP), and free wall longitudinal strain (RVFWLS). Satisfactory BPA was defined as mean pulmonary arterial pressure (mPAP) <25 mm Hg or improvement in mPAP > 10 mm Hg after BPA. Patients were divided into two groups according to mPAP values: group I had satisfactory BPA outcomes; group Ⅱ had unsatisfactory BPA outcomes. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve was used to determine the optimal cutoff values and the ability of RVFWLS to predict successful BPA outcomes. RESULTS: After BPA, SPAP measured by echocardiography (SPAPecho ) and RIMP decreased, but TAPSE, RVFAC, and RVFWLS increased. Before BPA, group Ⅰ had significantly better RV function than group Ⅱ. Multifactor logistic regression analysis identified RVFWLS as an independent factor associated with satisfactory BPA outcomes. The optimal cutoff value for RVFWLS in predicting satisfactory BPA outcomes was -12.2%. CONCLUSIONS: Balloon pulmonary angioplasty improves RV function in CTEPH patients. RVFWLS is a valuable noninvasive tool with which to assess the treatment effects of BPA. CTEPH patients with lower RVFWLS may have limited benefit from BPA.

Iron status is linked to disease severity after avian influenza virus H7N9 infection.

BACKGROUND AND OBJECTIVES: The high mortality rate of H7N9 strain of avian influenza virus (AIV) infected patients has been a major clinical concern. Iron overload increases the susceptibility of host for several kinds of microbial infection. However, the study on patients' iron and ferritin status associated with clinical outcome of AIVH7N9 virus infection is poorly understood, and in order to explain the linkage we carried out this study. METHODS AND STUDY DESIGN: We retrospectively collected serum from 46 patients infected with H7N9 virus from the hospital in Hangzhou city, Zhejiang province of China in 2013. We measured the level of serum iron and ferritin by Enzyme-Linked Immunosorbent Assay (ELISA). The correlation analysis of iron and ferritin with disease severity was done by SPSS 16.0 and MedCalc Software. RESULTS: After H7N9 infection, there is a reduction in iron level and an increase in ferritin, hepcidin and C-reactive protein (CRP) level in patient's serum compared to those of the control (p<0.001), and there's little correlation between procalcitonin (PCT) level and H7N9 infection. At week 1 and week 2 post-infection, serum iron level is much lower and ferritin level is much higher in the patients who died later than those in the patients who survived. The sensitivity, specificity, and Area Under the Curve (AUC) of the assay was calculated with MedCalc software and they were 85.5%, 65.9% and 0.803 for iron and 84.9%, 80.7% and 0.900 for ferritin, 95.2%, 51.1% and 0.684 for PCT and 100%, 94.6% and 0.988 for CRP, respectively. CONCLUSIONS: Our study found that low serum iron and high serum ferritin levels are correlated with the disease severity of H7N9-infected patients and can predict fatal outcomes.

Copper-catalyzed acylation of pyrazolones with aldehydes to afford 4-acylpyrazolones.

Copper-catalyzed direct acylation of the alkenyl C-H bond in 1,2-dihydro-3H-pyrazol-3-ones has been developed, affording a series of 4-acylpyrazolones in moderate to good yields. Notably, this protocol involves readily accessible substrates and reagents, which have good functional group tolerance leading to pyrazolone derivatives under mild reaction conditions.

Impaired left ventricular mechanics and functional reserve are associated with reduced exercise capacity in patients with hypertrophic cardiomyopathy.

BACKGROUND: Reduced metabolic equivalents (METs) are an indicator of exercise intolerance, which predicts poor prognosis in hypertrophic cardiomyopathy (HCM) patients. We sought to evaluate the changes in left ventricular (LV) mechanics and functional reserves, as well as their association with functional capacity in HCM patients. METHODS: Seventy HCM patients and thirty controls were included in this study. LV mechanics were evaluated at rest and during exercise by echocardiography and two-dimensional speckle-tracking imaging to obtain parameters of functional reserve, LV global longitudinal strain (LVGLS), strain rate (SR), and circumferential strain. RESULTS: Hypertrophic cardiomyopathy (HCM) patients had lower LVGLS, systolic SR, early and late diastolic SR at rest and during exercise, and reduced absolute and relative systolic and diastolic reserve compared to controls. LV circumferential strain was significantly higher at rest but lower during exercise in HCM patients. Exercise capacity was markedly reduced in HCM patients, and peak exercise LVGLS (LVGLS-exe) significantly correlated with exercise capacity. Multivariate regression analyses showed that LVGLS-exe, LV filling pressure during exercise (E/e'-exe), and LV mass index (LVMI) were independent predictors of exercise capacity. Moreover, LVGLS-exe displayed incremental predictive value over E/e'-exe and LVMI for exercise intolerance. Receiver operating characteristic curve analysis showed LVGLS-exe had optimal accuracy for predicting exercise intolerance in HCM patients. CONCLUSIONS: Hypertrophic cardiomyopathy (HCM) patients have reduced LV mechanics at rest and during exercise and impaired mechanical reserve. LVGLS-exe is associated with exercise capacity and is an optimal predictive value for reduced exercise capacity in HCM patients.

Iron deficiency response gene Femu2 plays a positive role in protecting Chlamydomonas reinhardtii against salt stress.

BACKGROUND: Iron deficiency related gene, Femu2, encodes protein homologous to a C2H2-type zinc finger protein, which participates in the regulation of FOX1 gene induced by iron (Fe) deficiency in Chlamydomonas reinhardtii. In this study, we investigate the gene function of Femu2 in response to salt stress in C. reinhardtii. METHODS: Femu2-overexpressing and Femu2-silencing transgenic cells were analyzed under salt stress. Several physiological indices were measured, and global changes in gene expression were investigated via RNA-seq. RESULTS: Compared with that of the non-treated control, the transcript levels of Femu2 were dramatically induced by iron deficiency and can also be significantly induced after algal cell exposure to Tris-acetate-phosphate (TAP) medium with 100 and 150mM NaCl. The promoter also responded to NaCl induction. Femu2-overexpressing transgenic algal cells exhibited significantly enhanced tolerance to salt stress. Conversely, Femu2-silencing cells showed higher sensitivity to salt stress than the control. Physiological analyses revealed that the overexpression of Femu2 increased the contents of proline and soluble sugars in transgenic cells under high salinity and that silencing Femu2 resulted in increased malondialdehyde level and decreased superoxide dismutase activity. RNA-seq results showed that a total of 248 genes have opposite expression profiles and that 5508 and 2120 genes were distinctly up-regulated or down-regulated in Femu2-overexpressing and Femu2-silencing transgenic cells under salt stress, respectively. CONCLUSION: Femu2 may play an important positive role in protecting C. reinhardtii against salt stress. GENERAL SIGNIFICANCE: The results of this study indicated that Femu2 may be useful in improving plant salt tolerance.

Expression, purification, and characterization of mouse nesfatin-1 in Escherichia coli.

Nesfatin-1 is a newly discovered satiety molecule expressed mainly in the hypothalamic nuclei. It suppresses both short-term and long-term appetite. Six synthetic deoxyoligonucleotides overlapped by PCR encoding nesfatin-1 were cloned into a pET28a vector after the hexa-histidine-tagged multiple cloning sites sequence with an enterokinase recognition site incorporated in-between. The recombinant plasmid was transformed into Escherichia coli strain Rosetta to express the fusion protein, which constituted 27% of the total cell proteins. After purified by Ni-sepharose affinity chromatography, the fusion protein was treated with enterokinase to release nesfatin-1. The nesfatin-1 sample was further purified with reverse-phase high performance liquid chromatography (HPLC), and its molecular weight was determined by mass spectrometry. The biological activities of recombinant nesfatin-1 were also assessed using in vivo animal models. The method described here promises to produce about 8 mg biologically active nesfatin-1 with homogeneity over 98% from 1-L shaking flask culture of E. coli, which can be considered as an easy and cost-effective way to synthesize nesfatin-1.

Newly Emergent Highly Pathogenic H5N9 Subtype Avian Influenza A Virus.

UNLABELLED: The novel H7N9 avian influenza virus (AIV) was demonstrated to cause severe human respiratory infections in China. Here, we examined poultry specimens from live bird markets linked to human H7N9 infection in Hangzhou, China. Metagenomic sequencing revealed mixed subtypes (H5, H7, H9, N1, N2, and N9). Subsequently, AIV subtypes H5N9, H7N9, and H9N2 were isolated. Evolutionary analysis showed that the hemagglutinin gene of the novel H5N9 virus originated from A/Muscovy duck/Vietnam/LBM227/2012 (H5N1), which belongs to clade 2.3.2.1. The neuraminidase gene of the novel H5N9 virus originated from human-infective A/Hangzhou/1/2013 (H7N9). The six internal genes were similar to those of other H5N1, H7N9, and H9N2 virus strains. The virus harbored the PQRERRRKR/GL motif characteristic of highly pathogenic AIVs at the HA cleavage site. Receptor-binding experiments demonstrated that the virus binds α-2,3 sialic acid but not α-2,6 sialic acid. Identically, pathogenicity experiments also showed that the virus caused low mortality rates in mice. This newly isolated H5N9 virus is a highly pathogenic reassortant virus originating from H5N1, H7N9, and H9N2 subtypes. Live bird markets represent a potential transmission risk to public health and the poultry industry. IMPORTANCE: This investigation confirms that the novel H5N9 subtype avian influenza A virus is a reassortant strain originating from H5N1, H7N9, and H9N2 subtypes and is totally different from the H5N9 viruses reported before. The novel H5N9 virus acquired a highly pathogenic H5 gene and an N9 gene from human-infecting subtype H7N9 but caused low mortality rates in mice. Whether this novel H5N9 virus will cause human infections from its avian host and become a pandemic subtype is not known yet. It is therefore imperative to assess the risk of emergence of this novel reassortant virus with potential transmissibility to public health.