The haemagglutinin-neuraminidase protein of velogenic Newcastle disease virus enhances viral infection through NF-κB-mediated programmed cell death.

The haemagglutinin-neuraminidase (HN) protein, a vital membrane glycoprotein, plays a pivotal role in the pathogenesis of Newcastle disease virus (NDV). Previously, we demonstrated that a mutation in the HN protein is essential for the enhanced virulence of JS/7/05/Ch, a velogenic variant NDV strain originating from the mesogenic vaccine strain Mukteswar. Here, we explored the effects of the HN protein during viral infection in vitro using three viruses: JS/7/05/Ch, Mukteswar, and an HN-replacement chimeric NDV, JS/MukHN. Through microscopic observation, CCK-8, and LDH release assays, we demonstrated that compared with Mukteswar and JS/MukHN, JS/7/05/Ch intensified the cellular damage and mortality attributed to the mutant HN protein. Furthermore, JS/7/05/Ch induced greater levels of apoptosis, as evidenced by the activation of caspase-3/8/9. Moreover, JS/7/05/Ch promoted autophagy, leading to increased autophagosome formation and autophagic flux. Subsequent pharmacological experiments revealed that inhibition of apoptosis and autophagy significantly impacted virus replication and cell viability in the JS/7/05/Ch-infected group, whereas less significant effects were observed in the other two infected groups. Notably, the mutant HN protein enhanced JS/7/05/Ch-induced apoptosis and autophagy by suppressing NF-κB activation, while it mitigated the effects of NF-κB on NDV infection. Overall, our study offers novel insights into the mechanisms underlying the increased virulence of NDV and serves as a reference for the development of vaccines.

Metabolic Syndrome and the Risk of Kidney Stones: a Large-scale Cohort Study from 487,860 UK Biobank participants.

OBJECTIVE: While some studies have suggested an association between metabolic syndrome and kidney stones, the quality and level of evidence in these studies vary. Whether some individual characteristics and clustering of metabolic syndrome traits increase the risk of kidney stones has not been examined in a large-scale prospective cohort. MATERIALS: We conducted a retrospective analysis of data from a prospective cohort of 487,860 UK Biobank participants who were free from kidney stones at baseline. The presence of metabolic syndrome was based on five criteria: abdominal obesity, high triglyceride levels, low high-density lipoprotein (HDL) cholesterol levels, high blood pressure (HBP), and type 2 diabetes mellitus (T2DM). Cox proportional hazards regression models were used to evaluate the association between metabolic syndrome and risk of kidney stones. RESULTS: After an average follow-up period of 12.6 years, a total of 5,213 of the 487,860 participants included in the UK Biobank study developed kidney stones. The partial traits of metabolic syndrome, including waist circumference (HR: 1.15, 95% CI: 1.10-1.20), HDL cholesterol (0.66, 0.55-0.79), HBP (1.11, 1.03-1.19) and T2DM (1.14, 1.04-1.21), were independently associated with the occurrence of kidney stones. The clustering of metabolic syndrome is significantly associated with kidney stone formation, and as the number of metabolic syndrome traits increases, the risk of kidney stones gradually increases. CONCLUSION: Metabolic syndrome is a significant and independent risk factor for the development of kidney stones. This association suggests that kidney stones may represent a systemic disorder influenced by the interplay of various metabolic risk factors.

Clathrin light chains negatively regulate plant immunity by hijacking the autophagy pathway.

The crosstalk between clathrin-mediated endocytosis (CME) and the autophagy pathway has been reported in mammals; however, the interconnection of CME with autophagy has not been established in plants. Here, we report that the Arabidopsis CLATHRIN LIGHT CHAIN (CLC) subunit 2 and 3 double mutant, clc2-1 clc3-1, phenocopies Arabidopsis AUTOPHAGY-RELATED GENE (ATG) mutants in both autoimmunity and nutrient sensitivity. Accordingly, the autophagy pathway is significantly compromised in the clc2-1 clc3-1 mutant. Interestingly, multiple assays demonstrate that CLC2 directly interacts with ATG8h/ATG8i in a domain-specific manner. As expected, both GFP-ATG8h/GFP-ATG8i and CLC2-GFP are subjected to autophagic degradation, and degradation of GFP-ATG8h is significantly reduced in the clc2-1 clc3-1 mutant. Notably, simultaneous knockout of ATG8h and ATG8i by CRISPR-Cas9 results in enhanced resistance against Golovinomyces cichoracearum, supporting the functional relevance of the CLC2-ATG8h/8i interactions. In conclusion, our results reveal a link between the function of CLCs and the autophagy pathway in Arabidopsis.

Dual N-linked glycosylation at residues 133 and 158 in the hemagglutinin are essential for the efficacy of H7N9 avian influenza virus like particle vaccine in chickens and mice.

H7N9 subtype avian influenza virus (AIV) poses a great challenge to poultry industry. Virus-like particle (VLP) is a prospective alternative for the traditional egg-based influenza vaccines. N-linked glycosylation (NLG) regulates the efficacy of influenza vaccines, whereas the impact of NLG modifications on the efficacy of influenza VLP vaccines remains unclear. Here, H7N9 VLPs were assembled in insect cells through co-infection with the baculoviruses expressing the NLG-modified hemagglutinin (HA), neuraminidase and matrix proteins, and the VLP vaccines were assessed in chickens and mice. NLG modifications significantly enhanced hemagglutination-inhibition and virus neutralization antibody responses in mice, rather than in chickens, because different immunization strategies were used in these animal models. The presence of dual NLG at residues 133 and 158 significantly elevated HA-binding IgG titers in chickens and mice. The VLP vaccines conferred complete protection and significantly suppressed virus replication and lung pathology post challenge with H7N9 viruses in chickens and mice. VLP immunization activated T cell immunity-related cytokine response and inhibited inflammatory cytokine response in mouse lung. Of note, the presence of dual NLG at residues 133 and 158 optimized the capacity of the VLP vaccine to stimulate interleukin-4 expression, inhibit virus shedding or alleviate lung pathology in chickens or mice. Intriguingly, the VLP vaccine with NLG addition at residue 133 provided partial cross-protection against the H5Nx subtype AIVs in chickens and mice. In conclusion, dual NLG at residues 133 and 158 in HA can be potentially used to enhance the efficacy of H7N9 VLP vaccines in chickens and mammals.

Research overview on the genetic mechanism underlying the biosynthesis of polysaccharide in tuber plants.

Tuber plants are of great significance in the world as human food crops. Polysaccharides, important metabolites in tuber plants, also serve as a source of innovative drugs with significant pharmacological effects. These drugs are particularly known for their immunomodulation and antitumor properties. To fully exploit the potential value of tuber plant polysaccharides and establish a synthetic system for their targeted synthesis, it is crucial to dissect their metabolic processes and genetic regulatory mechanisms. In this article, we provide a comprehensive summary of the basic pathways involved in the synthesis of various types of tuber plant polysaccharides. We also outline the key research progress that has been made in this area in recent years. We classify the main types and functions of tuber plant polysaccharides and analyze the biosynthetic processes and genetic regulation mechanisms of key enzymes involved in the metabolic pathways of starch, cellulose, pectin, and fructan in tuber plants. We have identified hexokinase and glycosyltransferase as the key enzymes involved in the polysaccharide synthesis process. By elucidating the synthesis pathway of polysaccharides in tuber plants and understanding the underlying mechanism of action of key enzymes in the metabolic pathway, we can provide a theoretical framework for enhancing the yield of polysaccharides and other metabolites in plant culture cells. This will ultimately lead to increased production efficiency.

Partially knocking out NtPDK1a/1b/1c/1d simultaneously in Nicotiana tabacum using CRISPR/CAS9 technology results in auxin-related developmental defects.

The eukaryotic AGC protein kinase subfamily (protein kinase A/ protein kinase G/ protein kinase C-family) is involved in regulating numerous biological processes across kingdoms, including growth and development, and apoptosis. PDK1(3-phosphoinositide-dependent protein kinase 1) is a conserved serine/threonine kinase in eukaryotes, which is both a member of AGC kinase and a major regulator of many other downstream AGC protein kinase family members. Although extensively investigated in model plant Arabidopsis, detailed reports for tobacco PDK1s have been limited. To better understand the functions of PDK1s in tobacco, CRISPR/CAS9 transgenic lines were generated in tetraploid N. tabacum, cv. Samsun (NN) with 5-7 of the 8 copies of 4 homologous PDK1 genes in tobacco genome (NtPDK1a/1b/1c/1d homologs) simultaneously knocked out. Numerous developmental defects were observed in these NtPDK1a/1b/1c/1d CRISPR/CAS9 lines, including cotyledon fusion leaf shrinkage, uneven distribution of leaf veins, convex veins, root growth retardation, and reduced fertility, all of which reminiscence of impaired polar auxin transport. The severity of these defects was correlated with the number of knocked out alleles of NtPDK1a/1b/1c/1d. Consistent with the observation in Arabidopsis, it was found that the polar auxin transport, and not auxin biosynthesis, was significantly compromised in these knockout lines compared with the wild type tobacco plants. The fact that no homozygous plant with all 8 NtPDK1a/1b/1c/1d alleles being knocked out suggested that knocking out 8 alleles of NtPDK1a/1b/1c/1d could be lethal. In conclusion, our results indicated that NtPDK1s are versatile AGC kinases that participate in regulation of tobacco growth and development via modulating polar auxin transport. Our results also indicated that CRISPR/CAS9 technology is a powerful tool in resolving gene redundancy in polyploidy plants.

The HN protein of Newcastle disease virus induces cell apoptosis through the induction of lysosomal membrane permeabilization.

Lysosomes are acidic organelles that mediate the degradation and recycling of cellular waste materials. Damage to lysosomes can cause lysosomal membrane permeabilization (LMP) and trigger different types of cell death, including apoptosis. Newcastle disease virus (NDV) can naturally infect most birds. Additionally, it serves as a promising oncolytic virus known for its effective infection of tumor cells and induction of intensive apoptotic responses. However, the involvement of lysosomes in NDV-induced apoptosis remains poorly understood. Here, we demonstrate that NDV infection profoundly triggers LMP, leading to the translocation of cathepsin B and D and subsequent mitochondria-dependent apoptosis in various tumor and avian cells. Notably, the released cathepsin B and D exacerbate NDV-induced LMP by inducing the generation of reactive oxygen species. Additionally, we uncover that the viral Hemagglutinin neuraminidase (HN) protein induces the deglycosylation and degradation of lysosome-associated membrane protein 1 (LAMP1) and LAMP2 dependent on its sialidase activity, which finally contributes to NDV-induced LMP and cellular apoptosis. Overall, our findings elucidate the role of LMP in NDV-induced cell apoptosis and provide novel insights into the function of HN during NDV-induced LMP, which provide innovative approaches for the development of NDV-based oncolytic agents.

Carbon dot enhanced peroxidase-like activity of platinum nanozymes.

As one of the most intriguing nanozymes, the platinum (Pt) nanozyme has attracted tremendous research interest due to its various catalytic activities but its application is still limited by its poor colloidal stability and low affinity to substrates. Here, we design a highly stable Pt@carbon dot (Pt@CD) hybrid nanozyme with enhanced peroxidase (POD)-like activity (specific activity of 1877 U mg-1). The Pt@CDs catalyze the decomposition of hydrogen peroxide (H2O2) to produce singlet oxygen and hydroxyl radicals and exhibit high affinity to H2O2 and high specificity to 3,3',5,5'-tetramethyl-benzidine. We reveal that both the hydroxyl and carbonyl groups of CDs could coordinate with Pt2+ and then regulate the charge state of the Pt nanozyme, facilitating the formation of Pt@CDs and improving the POD-like activity of Pt@CDs. Colorimetric detection assays based on Pt@CDs for H2O2, dopamine, and glucose with a satisfactory detection performance are achieved. Moreover, the Pt@CDs show a H2O2-involving antibacterial effect by destroying the cell membrane. Our findings provide new opportunities for designing hybrid nanozymes with desirable stability and catalytic performance by using CDs as nucleating templates and stabilizers.

Knocking out NtSARD1a/1b/1c/1d by CRISPR/CAS9 technology reduces the biosynthesis of salicylic acid (SA) and compromises immunity in tetraploid Nicotiana tabacum.

Salicylic acid (SA) is a key phyto-hormone that is essential for plant immunity. SARD1 (SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1), a member of the CBP60 (CALMODULIN-BINDING PROTEIN60) gene family, is one of the major transcription factors regulating the expression of the genes in SA biosynthesis. SARD1 has been extensively studied in model plant Arabidopsis. However, the function of SARD1 homologues in SA biosynthesis and immune responses have rarely been investigated in other plant species. In this study, the CRISPR/CAS9 (Clustered Regularly Interspersed Short Palindromic Repeats/CAS9) technology was used in creating transgenic tobacco mutant lines with 6-8 alleles of four NtSARD1 homologous genes (NtSARD1a/1b/1c/1d) knocked out. No significant difference in morphological phenotype was observed between the transgenic knockout lines and the wild type tobacco plants, indicating that knocking out NtSARD1s does not affect the growth and development in tobacco. However, knocking out or partially knocking out of NtSARD1a/b/c/d resulted in a significantly reduced expression of NtICS1, the key gene in SA biosynthesis pathway, and thus the subsequently decreased SA/SAG accumulations in response to Pst DC3000 (Pseudomonas syrangae pv.tomato DC3000) infection, indicating a key role of NtSARD1 genes in SA biosynthesis in tobacco. As a consequence of reduced SA/SAG accumulation, the Pst DC3000-induced expression of NtPR genes as well as the resistance to Pst DC3000 were both significantly reduced in these knockout lines compared with the wild type tobacco plants. Interestingly, the reductions in the SA/SAG level, NtPR gene induction and Pst DC3000 resistance were positively correlated with the number of alleles being knocked out. Furthermore, LUC reporter gene driven by the promoter of NtICS1 containing two G(A/T)AATT(T/G) motifs could be activated by NtSARD1a, suggesting that NtSARD1a could bind to the core G(A/T)AATT(T/G) motifs and thus activate the expression of LUC reporter. Taken together, our results demonstrated that the NtSARD1 proteins play essential roles in SA biosynthesis and immune responses in tobacco. Our results also demonstrated that the CRISPR/CAS9 technology can overcome gene redundancy and is a powerful tool to study gene functions in polyploid plant species.

The NP protein of Newcastle disease virus dictates its oncolytic activity by regulating viral mRNA translation efficiency.

Newcastle disease virus (NDV) has been extensively studied as a promising oncolytic virus for killing tumor cells in vitro and in vivo in clinical trials. However, the viral components that regulate the oncolytic activity of NDV remain incompletely understood. In this study, we systematically compared the replication ability of different NDV genotypes in various tumor cells and identified NP protein determines the oncolytic activity of NDV. On the one hand, NDV strains with phenylalanine (F) at the 450th amino acid position of the NP protein (450th-F-NP) exhibit a loss of oncolytic activity. This phenotype is predominantly associated with genotype VII NDVs. In contrast, the NP protein with a leucine amino acid at this site in other genotypes (450th-L-NP) can facilitate the loading of viral mRNA onto ribosomes more effectively than 450th-F-NP. On the other hand, the NP protein from NDV strains that exhibit strong oncogenicity interacts with eIF4A1 within its 366-489 amino acid region, leading to the inhibition of cellular mRNA translation with a complex 5' UTR structure. Our study provide mechanistic insights into how highly oncolytic NDV strains selectively promote the translation of viral mRNA and will also facilitate the screening of oncolytic strains for oncolytic therapy.

Magnetic Microbead-Based Herringbone Chip for Sensitive Detection of Human Immunodeficiency Virus.

The microfluidic chip-based nucleic acid detection method significantly improves the sensitivity since it precisely controls the microfluidic flow in microchannels. Nonetheless, significant challenges still exist in improving the detection efficiency to meet the demand for rapid detection of trace substances. This work provides a novel magnetic herringbone (M-HB) structure in a microfluidic chip, and its advantage in rapid and sensitive detection is verified by taking complementary DNA (cDNA) sequences of human immunodeficiency virus (HIV) detection as an example. The M-HB structure is designed based on controlling the magnetic field distribution in the micrometer scale and is formed by accumulation of magnetic microbeads (MMBs). Hence, M-HB is similar to a nanopore microstructure, which has a higher contact area and probe density. All of the above is conducive to improving sensitivity in microfluidic chips. The M-HB chip is stable and easy to form, which can linearly detect cDNA sequences of HIV quantitatively ranging from 1 to 20 nM with a detection limit of 0.073 nM. Compared to the traditional herringbone structure, this structure is easier to form and release by controlling the magnetic field, which is flexible and helps in further study. Results show that this chip can sensitively detect the cDNA sequences of HIV in blood samples, demonstrating that it is a powerful platform to rapidly and sensitively detect multiple nucleic acid-related viruses of infectious diseases.

Lack of causal association between epilepsy and dementia: A Mendelian randomization analysis.

OBJECTIVE: Epidemiological studies have reported an association between epilepsy and dementia. However, the causal relationship between epilepsy and the risk of dementia is not clear. We aimed to inspect the causal effect of epilepsy on memory loss and dementia. METHODS: We analyzed summary data of epilepsy, memory loss, and dementia from the genome-wide association study (GWAS) using the two-sample Mendelian randomization (MR) method. We used the estimated odds ratio of memory loss and dementia associated with each of the genetically defined traits to infer evidence for a causal relationship with the following exposures: all epilepsy, focal epilepsy (including focal epilepsy with hippocampal sclerosis, lesion-negative focal epilepsy, and focal epilepsy with other lesions), and genetic generalized epilepsy (including childhood absence epilepsy, generalized tonic-clonic seizures alone, Juvenile absence epilepsy, and Juvenile myoclonic epilepsy). RESULTS: According to the result of MR using the inverse variance weighted method (IVW), we found that genetically predicted epilepsy did not causally increase the risk of memory loss and dementia (p > 0.05). Results of the MR-Egger and weighted median method were consistent with the IVW method. CONCLUSIONS: No evidence has been found to support the notion that epilepsy can result in memory loss and dementia. The associations observed in epidemiological studies could be attributed, in part, to confounding or nongenetic determinants.

Nitrogen-bridged Fe-Cu Atomic Pair Sites for Efficient Electrochemical Ammonia Production and Electricity Generation with Zn-NO2 Batteries.

The development of environmentally sustainable and highly efficient technologies for ammonia production is crucial for the future advancement of carbon-neutral energy systems. The nitrite reduction reaction (NO2 RR) for generating NH3 is a promising alternative to the low-efficiency nitrogen reduction reaction (NRR), owing to the low N=O bond energy and high solubility of nitrite. In this study, we designed a highly efficient dual-atom catalyst with Fe-Cu atomic pair sites (termed FeCu DAC), and the as-developed FeCu DAC was able to afford a remarkable NH3 yield of 24,526 µg h-1 mgcat. -1 at -0.6 V, with a Faradaic Efficiency (FE) for NH3 production of 99.88 %. The FeCu DAC also exhibited exceptional catalytic activity and selectivity in a Zn-NO2 battery, achieving a record-breaking power density of 23.6 mW cm-2 and maximum NH3 FE of 92.23 % at 20 mA cm-2 . Theoretical simulation demonstrated that the incorporation of the Cu atom changed the energy of the Fe 3d orbital and lowered the energy barrier, thereby accelerating the NO2 RR. This study not only demonstrates the potential of galvanic nitrite-based cells for expanding the field of Zn-based batteries, but also provides fundamental interpretation for the synergistic effect in highly dispersed dual-atom catalysts.

Hemagglutinin affects replication, stability and airborne transmission of the H9N2 subtype avian influenza virus.

H9N2 subtype avian influenza virus (AIV) can transmit by direct as well as airborne contacts. It has been widespread in poultry and continued to contribute to zoonotic spillover events by providing its six internal genes for the reassortment of novel influenza viruses (eg, H7N9) that infect poultry and humans. Compared to H7N9, H9N2 virus displays an efficient airborne transmissibility in poultry, but the mechanisms of transmission difference have been insufficiently studied. The Hemagglutinin (HA) and viral polymerase acidic protein (PA) have been implicated in the airborne transmission of influenza A viruses. Accordingly, we generated the reassortant viruses of circulating airborne transmissible H9N2 and non-airborne transmissible H7N9 viruses carrying HA and/or PA gene. The introduction of the PA gene from H7N9 into the genome of H9N2 virus resulted in a reduction in airborne transmission among chickens, while the isolated introduction of the HA gene segment completely eliminated airborne transmission among chickens. We further showed that introduction of HA gene of non-transmissible H7N9 did not influence the HA/NA balance of H9N2 virus, but increased the threshold for membrane fusion and decreased the acid stability. Thus, our results indicate that HA protein plays a key role in replication, stability, and airborne transmission of the H9N2 subtype AIV.

Phosphorylation of PB2 at serine 181 restricts viral replication and virulence of the highly pathogenic H5N1 avian influenza virus in mice.

Influenza A virus (IAV) continues to pose a pandemic threat to public health, resulting a high mortality rate annually and during pandemic years. Posttranslational modification of viral protein plays a substantial role in regulating IAV infection. Here, based on immunoprecipitation (IP)-based mass spectrometry (MS) and purified virus-coupled MS, a total of 89 phosphorylation sites distributed among 10 encoded viral proteins of IAV were identified, including 60 novel phosphorylation sites. Additionally, for the first time, we provide evidence that PB2 can also be acetylated at site K187. Notably, the PB2 S181 phosphorylation site was consistently identified in both IP-based MS and purified virus-based MS. Both S181 and K187 are exposed on the surface of the PB2 protein and are highly conserved in various IAV strains, suggesting their fundamental importance in the IAV life cycle. Bioinformatic analysis results demonstrated that S181E/A and K187Q/R mimic mutations do not significantly alter the PB2 protein structure. While continuous phosphorylation mimicked by the PB2 S181E mutation substantially decreases viral fitness in mice, PB2 K187Q mimetic acetylation slightly enhances viral virulence in mice. Mechanistically, PB2 S181E substantially impairs viral polymerase activity and viral replication, remarkably dampens protein stability and nuclear accumulation of PB2, and significantly weakens IAV-induced inflammatory responses. Therefore, our study further enriches the database of phosphorylation and acetylation sites of influenza viral proteins, laying a foundation for subsequent mechanistic studies. Meanwhile, the unraveled antiviral effect of PB2 S181E mimetic phosphorylation may provide a new target for the subsequent study of antiviral drugs.

The Drosophila NPY-like system protects against chronic stress-induced learning deficit by preventing the disruption of autophagic flux.

Chronic stress may induce learning and memory deficits that are associated with a depression-like state in Drosophila melanogaster. The molecular and neural mechanisms underlying the etiology of chronic stress-induced learning deficit (CSLD) remain elusive. Here, we show that the autophagy-lysosomal pathway, a conserved cellular signaling mechanism, is associated with chronic stress in Drosophila, as indicated by time-series transcriptome profiling. Our findings demonstrate that chronic stress induces the disruption of autophagic flux, and chronic disruption of autophagic flux could lead to a learning deficit. Remarkably, preventing the disruption of autophagic flux by up-regulating the basal autophagy level is sufficient to protect against CSLD. Consistent with the essential role of the dopaminergic system in modulating susceptibility to CSLD, dopamine neuronal activity is also indispensable for chronic stress to induce the disruption of autophagic flux. By screening knockout mutants, we found that neuropeptide F, the Drosophila homolog of neuropeptide Y, is necessary for normal autophagic flux and promotes resilience to CSLD. Moreover, neuropeptide F signaling during chronic stress treatment promotes resilience to CSLD by preventing the disruption of autophagic flux. Importantly, neuropeptide F receptor activity in dopamine neurons also promotes resilience to CSLD. Together, our data elucidate a mechanism by which stress-induced excessive dopaminergic activity precipitates the disruption of autophagic flux, and chronic disruption of autophagic flux leads to CSLD, while inhibitory neuropeptide F signaling to dopamine neurons promotes resilience to CSLD by preventing the disruption of autophagic flux.

Silencing GmATG7 Leads to Accelerated Senescence and Enhanced Disease Resistance in Soybean.

Autophagy plays a critical role in nutrient recycling/re-utilizing under nutrient deprivation conditions. However, the role of autophagy in soybeans has not been intensively investigated. In this study, the Autophay-related gene 7 (ATG7) gene in soybeans (referred to as GmATG7) was silenced using a virus-induced gene silencing approach mediated by Bean pod mottle virus (BPMV). Our results showed that ATG8 proteins were highly accumulated in the dark-treated leaves of the GmATG7-silenced plants relative to the vector control leaves (BPMV-0), which is indicative of an impaired autophagy pathway. Consistent with the impaired autophagy, the dark-treated GmATG7-silenced leaves displayed an accelerated senescence phenotype, which was not seen on the dark-treated BPMV-0 leaves. In addition, the accumulation levels of both H2O2 and salicylic acid (SA) were significantly induced in the GmATG7-silenced plants compared with the BPMV-0 plants, indicating an activated immunity. Consistently, the GmATG7-silenced plants were more resistant against both Pseudomonas syringae pv. glycinea (Psg) and Soybean mosaic virus (SMV) compared with the BPMV-0 plants. However, the activated immunity in the GmATG7-silenced plant was not dependent upon the activation of MPK3/MPK6. Collectively, our results demonstrated that the function of GmATG7 is indispensable for autophagy in soybeans, and the activated immunity in the GmATG7-silenced plant is a result of impaired autophagy.

Mutations in HA and PA affect the transmissibility of H7N9 avian influenza virus in chickens.

Low pathogenic (LP) H7N9 avian influenza virus (AIV) emerged in 2013 and had spread widely over several months in China, experienced a noteworthy reduction in isolation rate in poultry and human since 2017. Here, we examined the transmission of H7N9 viruses to better understand viral spread and dissemination mechanisms. Three out of four viruses (2013-2016) could transmit in chickens through direct contact, and airborne transmission was confirmed in the JT157 (2016) virus. However, we did not detect the transmission of the two 2017 viruses, WF69 and AH395, through either direct or airborne exposure. Molecular analysis of genome sequence of two viruses identified eleven mutations located in viral proteins (except for matrix protein), such as PA (K362R and S364N) and HA (D167N, H7 numbering), etc. We explored the genetic determinants that contributed to the difference in transmissibility of the viruses in chickens by generating a series of reassortants in the JT157 background. We found that the replacement of HA gene in JT157 by that of WF69 abrogated the airborne transmission in recipient chickens, whereas the combination of HA and PA replacement led to the loss of airborne and direct contact transmission. Failure with contact transmission of the viruses has been associated with the emergence of the mutations D167N in HA and K362R and S364N in PA. Furthermore, the HA D167N mutation significantly reduced viral attachment to chicken lung and trachea tissues, while mutations K362R and S364N in PA reduced the nuclear transport efficiency and the PA protein expression levels in both cytoplasm and nucleus of CEF cells. The D167N substitution in HA reduced the H7N9 viral acid stability and avian-like receptor binding, while enhanced human-like receptor binding. Further analysis revealed these mutants grew poorly in vitro and in vivo. To conclude, H7N9 AIVs that contain mutations in the HA and PA protein reduced the viral transmissibility in chicken, and may pose a reduced threat for poultry but remain a heightened public health risk.