A vaccine targeting the RBD of the S protein of SARS-CoV-2 induces protective immunity.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a respiratory disease called coronavirus disease 2019 (COVID-19), the spread of which has led to a pandemic. An effective preventive vaccine against this virus is urgently needed. As an essential step during infection, SARS-CoV-2 uses the receptor-binding domain (RBD) of the spike protein to engage with the receptor angiotensin-converting enzyme 2 (ACE2) on host cells1,2. Here we show that a recombinant vaccine that comprises residues 319-545 of the RBD of the spike protein induces a potent functional antibody response in immunized mice, rabbits and non-human primates (Macaca mulatta) as early as 7 or 14 days after the injection of a single vaccine dose. The sera from the immunized animals blocked the binding of the RBD to ACE2, which is expressed on the cell surface, and neutralized infection with a SARS-CoV-2 pseudovirus and live SARS-CoV-2 in vitro. Notably, vaccination also provided protection in non-human primates to an in vivo challenge with SARS-CoV-2. We found increased levels of RBD-specific antibodies in the sera of patients with COVID-19. We show that several immune pathways and CD4 T lymphocytes are involved in the induction of the vaccine antibody response. Our findings highlight the importance of the RBD domain in the design of SARS-CoV-2 vaccines and provide a rationale for the development of a protective vaccine through the induction of antibodies against the RBD domain.

Structural and functional basis of low-affinity SAM/SAH-binding in the conserved MTase of the multi-segmented Alongshan virus distantly related to canonical unsegmented flaviviruses.

Alongshan virus (ALSV), a newly discovered member of unclassified Flaviviridae family, is able to infect humans. ALSV has a multi-segmented genome organization and is evolutionarily distant from canonical mono-segmented flaviviruses. The virus-encoded methyltransferase (MTase) plays an important role in viral replication. Here we show that ALSV MTase readily binds S-adenosyl-L-methionine (SAM) and S-adenosyl-L-homocysteine (SAH) but exhibits significantly lower affinities than canonical flaviviral MTases. Structures of ALSV MTase in the free and SAM/SAH-bound forms reveal that the viral enzyme possesses a unique loop-element lining side-wall of the SAM/SAH-binding pocket. While the equivalent loop in flaviviral MTases half-covers SAM/SAH, contributing multiple hydrogen-bond interactions; the pocket-lining loop of ALSV MTase is of short-length and high-flexibility, devoid of any physical contacts with SAM/SAH. Subsequent mutagenesis data further corroborate such structural difference affecting SAM/SAH-binding. Finally, we also report the structure of ALSV MTase bound with sinefungin, an SAM-analogue MTase inhibitor. These data have delineated the basis for the low-affinity interaction between ALSV MTase and SAM/SAH and should inform on antiviral drug design.

Development of a bispecific nanobody conjugate broadly neutralizes diverse SARS-CoV-2 variants and structural basis for its broad neutralization.

The continuous emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with increased transmissibility and profound immune-escape capacity makes it an urgent need to develop broad-spectrum therapeutics. Nanobodies have recently attracted extensive attentions due to their excellent biochemical and binding properties. Here, we report two high-affinity nanobodies (Nb-015 and Nb-021) that target non-overlapping epitopes in SARS-CoV-2 S-RBD. Both nanobodies could efficiently neutralize diverse viruses of SARS-CoV-2. The neutralizing mechanisms for the two nanobodies are further delineated by high-resolution nanobody/S-RBD complex structures. In addition, an Fc-based tetravalent nanobody format is constructed by combining Nb-015 and Nb-021. The resultant nanobody conjugate, designated as Nb-X2-Fc, exhibits significantly enhanced breadth and potency against all-tested SARS-CoV-2 variants, including Omicron sub-lineages. These data demonstrate that Nb-X2-Fc could serve as an effective drug candidate for the treatment of SARS-CoV-2 infection, deserving further in-vivo evaluations in the future.

Surgical treatment of multiple magnet ingestion by children: A single-center experience from China.

BACKGROUND: The incidence of magnet ingestion in children has escalated concurrent with the rise in popularity of magnetic playthings, bearing the capacity to induce substantial morbidity. AIM: The objective of this study was to encapsulate our accumulated expertise in handling pediatric cases featuring multiple magnetic foreign bodies within the gastrointestinal tract sometimes necessitating surgical intervention, as well as to formulate a clinical management algorithm. METHODS: This was a retrospective review of patients with multiple magnetic foreign bodies in the digestive tract, admitted to Shenzhen Children's Hospital, between January 2018 and December 2022. RESULTS: A total of 100 cases were included in this study, including 66 males and 34 females. The main clinical manifestation ns were abdominal pain and vomiting. All patients had abdominal x-ray, all of which indicated foreign bodies in the digestive tract. 33 patients had to undergo a surgical intervention. Among these cases, the gastrointestinal complications occurred in 31 patients, including gastric rupture (n = 9), intestinal obstruction (n = 11) and intestinal perforation (n = 30). Postoperative intestinal obstruction occurred in 6 children. There was no statistical significant difference in age and gender between the Surgical group and Non-surgical group, but the Surgical group had a higher number of magnets ([7.5(2-44) vs 4(2-20)], p = 0.009), a longer interval between time of misingestion to clinical visit ([48(7.2-480) vs 5(2-336)]hours, p < 0.001), and a longer length of hospital stay ([10(6-19) vs 2(1-8)]days, p < 0.001). CONCLUSIONS: Multiple magnet ingestion in children can lead to serious complications and carry severe risks. Timely diagnosis and effective treatment are crucial for managing such patients.

Crystal structure of SARS-CoV-2 nsp10 bound to nsp14-ExoN domain reveals an exoribonuclease with both structural and functional integrity.

The emergence of SARS-CoV-2 infection has posed unprecedented threat to global public health. The virus-encoded non-structural protein 14 (nsp14) is a bi-functional enzyme consisting of an exoribonuclease (ExoN) domain and a methyltransferase (MTase) domain and plays a pivotal role in viral replication. Here, we report the structure of SARS-CoV-2 nsp14-ExoN domain bound to its co-factor nsp10 and show that, compared to the SARS-CoV nsp10/nsp14-full-length complex, SARS-CoV-2 nsp14-ExoN retains an integral exoribonuclease fold and preserves an active configuration in the catalytic center. Analysis of the nsp10/nsp14-ExoN interface reveals a footprint in nsp10 extensively overlapping with that observed in the nsp10/nsp16 structure. A marked difference in the co-factor when engaging nsp14 and nsp16 lies in helix-α1', which is further experimentally ascertained to be involved in nsp14-binding but not in nsp16-engagement. Finally, we also show that nsp10/nsp14-ExoN is enzymatically active despite the absence of nsp14-MTase domain. These data demonstrate that SARS-CoV-2 nsp10/nsp14-ExoN functions as an exoribonuclease with both structural and functional integrity.

Possible Role of Docosahexaenoic Acid in Response to Diarrhetic Shellfish Toxins in the Mussel Perna viridis.

Marine bivalves are rich in docosahexaenoic acid (DHA), a polyunsaturated fatty acid known to be beneficial for human health; however, the potential role of DHA in protecting shellfish from the toxicity of diarrhetic shellfish toxins (DSTs) remains poorly understood. Here, we aimed to study the effect of DHA on the response of the bivalve, Perna viridis, to DSTs by using LC-MS/MS, RT-qPCR, and histological examination. In this study, we observed that the DHA content decreased significantly with esterification of DSTs in the digestive gland of the mussel P. viridis after 96 h of exposure to Prorocentrum lima, a DST-producing dinoflagellate. The addition of DHA significantly increased the esterification level of DSTs and increased the expression of Nrf2 signaling pathway-related genes and enzyme activities, alleviating the damage of DSTs to digestive glands. These results suggested that DHA may mediate the esterification of DSTs and activation of the Nrf2 signaling pathway in P. viridis to protect mussels from the toxic effects of DSTs. This study may provide new insights regarding the response of bivalves to DSTs and lay the foundation for uncovering the role of DHA in environmental adaptation of bivalves.

N-Cyanation of Primary and Secondary Amines with Cyanobenzio-doxolone (CBX) Reagent.

An efficient electrophilic N-cyanation of amines with a stable and less-toxic cyanobenziodoxole reagent towards the synthesis of cyanamides is disclosed. This synthetically practicable strategy allows the construction of a wide variety of cyanamides under very mild and simple conditions with a broad functional group compatibility, and showcases a huge potential in late-stage modification of complex molecules.

Aminoacylase 1 (ACY-1) Mediates the Proliferation and Migration of Neuroblastoma Cells in Humans Through the ERK/Transforming Growth Factor ß (TGF-ß) Signaling Pathways.

BACKGROUND Aminoacylase 1 (ACY-1) is a cytosolic enzyme that catalyzes amino acid deacylation and has been reported to participate in various human diseases. However, the role and mechanism of ACY-1 in neuroblastoma (NB) are not completely understood. The aim of this study was to elucidate the role of ACY-1 in NB. MATERIAL AND METHODS Overexpression and knockdown of ACY-1 in human NB cells were performed, and the transfection efficiency was assessed through fluorescence microscopy, real-time PCR, and western blotting. The effect of ACY-1 on tumorigenesis and metastasis was determined by cell counting, colony formation, wound healing, flow cytometry, and transwell invasion assays in vitro, and the signaling pathway was examined using western blotting. RESULTS ACY-1 overexpression inhibited proliferation and induced apoptosis in human NB cells. ACY-1 inhibited the colony formation ability, migration, and invasion of SH-SY5Y cell lines. Moreover, the ERK1/2 and TGF-ß1 signaling pathways were more active when ACY-1 was overexpressed in NB cells. However, the knockdown of ACY-1 in SH-SY5Y cell lines showed the opposite effects. CONCLUSIONS ACY-1 regulates the proliferation, migration, and invasion of human NB cells through the ERK1/2 and TGF-ß1 signaling pathways, implying that ACY-1 may serve as a therapeutic target for patients with NB.

The novel regulators CheP and CheQ control the core chemotaxis operon cheVAW in Campylobacter jejuni.

Campylobacter jejuni is the leading cause of foodborne gastrointestinal illness worldwide, and chemotaxis plays an important role in its host colonization and pathogenesis. Although many studies on chemotaxis have focused on the physical organization and signaling mechanism of the system's protein complex, much less is known about the transcriptional regulation of its components. Here, we describe two novel regulators, CJJ81176_0275 and CJJ81176_0276 (designated as CheP and CheQ), which specifically activate the transcription of the chemotaxis core genes cheV, cheA and cheW in C. jejuni and they are also essential for chemotactic responses. CheP has a single HD-related output domain (HDOD) domain and can promote CheQ binding to the cheVAW operon promoter through a protein-protein interaction. Mutagenesis analyses identified key residues critical for CheP function and/or interaction with CheQ. Further structural characterization of CheQ revealed a novel fold with strong positive surface charges that allow for its DNA binding. These findings reveal the gene regulatory mechanism of the chemotaxis system in an important bacterial pathogen and provide potential anti-virulence targets for campylobacteriosis treatment. In addition, ChePQ is an example of how proteins with the widespread but functionally obscure HDOD can coordinate with a signal output DNA-binding protein/domain to regulate the expression of important signaling pathways.

Selective 1,2-Aryl-Aminoalkylation of Alkenes Enabled by Metallaphotoredox Catalysis.

A highly chemo- and regioselective intermolecular 1,2-aryl-aminoalkylation of alkenes by photoredox/nickel dual catalysis is described here. This three-component conjunctive cross-coupling is highlighted by its first application of primary alkyl radicals, which were not compatible in previous reports. The readily prepared α-silyl amines could be transferred to α-amino radicals by photo-induced single electron transfer step. The radical addition/cross-coupling cascade reaction proceeds under mild, base-free and redox-neutral conditions with good functional group tolerance, and importantly, provides an efficient and concise method for the synthesis of structurally valuable α-aryl substituted γ-amino acid derivatives motifs.

Crystal structure of PA0833 periplasmic domain from Pseudomonas aeruginosa reveals an unexpected enlarged peptidoglycan binding pocket.

PA0833 of Pseudomonas aeruginosa is recently identified as an OmpA C-like protein that is able to interact with bacterial peptidoglycan (PGN). In this study, we reported the biochemical and structural characterization of the PGN-binding periplasmic-domain of PA0833 (PA0833-PD). Via mutagenesis, key residues responsible for engaging PGN were identified, which also enables us to localize the PGN-binding pocket in a 2.0 Šcrystal structure solved in this study. In contrast to its homologous proteins (as represented by AbOmpA-PD of Acinetobacter baumannii) that interact with PGN by directly engaging the DAP (diaminopimelate) moiety, PA0833-PD exhibits an enlarged PGN-binding pocket due to residue insertions and the formation of an extra α-helix in one lateral side of the pocket. Accordingly, single DAP molecule does not show detectable interactions with PA0833-PD in solution, highlighting that other PGN-components, in addition to DAP, are also required to restore the full binding capacity observed between PA0833 and PGN.

Suppressing microRNA-29c promotes biliary atresia-related fibrosis by targeting DNMT3A and DNMT3B.

This study was designed to investigate the potential role of microRNA-29c (miR-29c) in biliary atresia-related fibrosis. The expression of miR-29c was determined in 15 pairs of peripheral blood samples from infants with biliary atresia (BA) and infants with non-BA neonatal cholestasis using quantitative real-time PCR. EMT was established by induction with TGF-ß1 in HIBEpiC cells. MiR-29c was inhibited by lipofectamine transfection. The expressions of proteins related to epithelial-mesenchymal transition (EMT), i.e., E-cadherin, N-cadherin and vimentin, were determined using quantitative real-time PCR and western blotting. Direct interaction between miR-29c and DNMT3A and DNMT3B was identified using a luciferase reporter assay. The expressions of DNMT3A and DNMT3B were suppressed by treatment with SGI-1027. Patients with BA showed significantly lower miR-29c levels in peripheral blood samples than the control subjects. In vitro, TGF-ß1-induced EMT significantly decreased the expression of miR-29c. Downregulation of miR-29c had a promotional effect on BA-related fibrosis in HIBEpiC cells, as confirmed by the decrease in E-cadherin and increase in N-cadherin and vimentin levels. MiR-29c was found to target the 3'UTR of DNMT3A and DNMT3B and inhibit their expression. Suppression of DNMT3A and DNMT3B reversed the effects of miR-29c downregulation on BA-related fibrosis in HIBEpiC cells. These data suggest that BA-related fibrosis is closely associated with the occurrence of EMT in HIBEpiC cells. MiR-29c might be a candidate for alleviating BA-related fibrosis by targeting DNMT3A and DNMT3B.

High mobility indium tin oxide thin film and its application at infrared wavelengths: model and experiment.

In this work, high mobility indium tin oxide (ITO) thin films with uniform crystallographic orientation are prepared. These films present a wide-range transmittance window and could be used as transparent electrodes at ultraviolet-visible-infrared wavelengths. In particular, the ITO thin film is characterized by low resistivity (5.1 × 10-4 Ωcm) and high infrared transmittance (88.5% at 2.5 µm) due to the improved mobility, achieving higher infrared performance than other transparent conductive materials. A model based on carrier's transport theory and Lorentz-Drude dielectric function is proposed to quantitatively calculate the optical performance of conductive thin films under the influence of plasma effect. The calculation demonstrates that ITO is a suitable electrode material for near/middle infrared optoelectronic applications.

Crystal structure of Usutu virus envelope protein in the pre-fusion state.

BACKGROUND: Usutu virus (USUV) is a mosquito-born flavivirus that can infect multiple avian and mammalian species. The viral surface envelope (E) protein functions to initiate the viral infection by recognizing cellular receptors and mediating the subsequent membrane fusion, and is therefore a key virulence factor involved in the pathogenesis of USUV. The structural features of USUV-E, however, remains un-investigated thus far. FINDINGS: Using the crystallographic method, we determined the structure of USUV-E in the pre-fusion state at 2.0 angstrom. As expected, the overall fold of USUV-E, with three ß-barrel domains (DI, DII, and DIII), resembles those of other flaviviral E proteins. In comparison to other pre-fusion E structures, however, USUV-E exhibits an apparently enlarged inter-domain angle between DI and DII, leading to a more extended conformation. Using our structure and other reported pre-fusion E structures, the DI-DII domain-angle difference was analyzed in a pairwise manner. The result shows a much higher degree of variations for USUV-E, indicating the potential for remarkable DI-DII domain angle plasticity among flaviviruses. CONCLUSION: We report the crystal structure of USUV-E and show that its pre-fusion structure has an enlarged DI-DII domain-angle which has not been observed in other reported flaviviral E-structures.

Creating a Learning Culture for Medical Consortia in China.

In China's recent health care reforms, both individuals and organizations have shown an ever-growing desire and demand for new knowledge and skills. A health care delivery system (HCDS) should explore new ways for creating a learning organization (LO) and should organically combine HCDS culture construction with the LO construction to build a cultural atmosphere that is conducive to the development of the LO. This article describes the implementation phase, characteristics, and realization strategy of an HCDS construction for the ultimate purpose of enhancing HCDS cohesion, solidarity, and sustainable development.

Evolutionary patterns and microscopic mechanisms of strength in mine tailings backfilled with waste glass.

In order to promote the sustainable use of resources and reduce the waste of waste glass and tailings resources. The present study focuses on a fluorite mine as the research subject, utilizing coarse tailings, fine tailings, cement substitute-curing agent, and recycled waste glass as the primary raw materials. It investigates the changes in compressive strength of coarse tailing with varying sand- binder ratios and glass content at 3-day, 7-day, and 28-day intervals when the filling slurry concentration is set at 77% and the ratio of coarse tailings to fine tailings is maintained at 2:1. The findings indicate that there is minimal impact on the compressive strength of test blocks when using a sand binder ratio of 4:1 and a glass sand content below 10%. However, once the glass sand content exceeds 10%, a significant decline in compressive strength occurs. Scanning electron microscope (SEM) images reveal ettringite crystal formation in test blocks with both 0% and 25% glass sand content due to high levels of Na2O in the glass sand. This leads to internal expansion within test blocks resulting in reduced strength. Notably, when using a sand-binder ratio of 8:1 along with a glass sand content of 25%, early strength characteristics are observed for test blocks. Furthermore, incorporating glass sand has little influence on late-stage strength for backfill when employing either an 8:1 or 12:1 sand-binder ratio. Based on this experiment conducted under conditions including mass concentration of 77%, the optimal waste-glass-to-mine-tailings-filling-sand-binder-ratio is determined as 8:1with a corresponding glass content of 25%.

Response of garlic (Allium sativum L.) to the combined toxicity of microplastics and arsenic.

The extensive utilization of mulch films in agricultural settings, coupled with the persistence of microplastic remnants in soil following the natural degradation of plastics, has given rise to detrimental microplastic impacts on crops. Arsenic (As) contamination in the environment is known to accumulate in crops through aquatic pathways or soil. Garlic (Allium sativum L.), a globally popular crop and seasoning, contains alliin, a precursor of its flavor compounds with medicinal properties. While alliin exhibits antimicrobial and antioxidant effects in garlic, its response to microplastics and arsenic has not been thoroughly investigated, specifically in terms of microplastic or As uptake. This study aimed to explore the impact of varied stress concentrations of microplastics on the toxicity, migration, and accumulation of As compounds. Results demonstrated that polystyrene (PS) fluorescent microspheres, with an 80 nm diameter, could permeate garlic bulbs through the root system, accumulating within vascular tissues and intercellular layers. Low concentrations of PS (10 and 20 mg L-1) and As (2 mg L-1) mitigated the production and accumulation of reactive oxygen species (ROS) and antioxidant enzymes in garlic. Conversely, garlic exhibited reduced root vigor, substance uptake, and translocation when treated with elevated As concentrations (4 mg L-1) in conjunction with PS concentrations of 40 and 80 mg L-1. An escalation in PS concentration facilitated As transport into bulbs but led to diminished As accumulation and biomass in the root system. Notably, heightened stress levels weakened garlic's antioxidant defense system, encompassing sulfur allicin and phytochelatin metabolism, crucial for combating the phytotoxicity of PS and As. In summary, PS exerted a detrimental influence on garlic, exacerbating As toxicity. The findings from this study offer insights for subsequent investigations involving Liliaceae plants.

The impact of microplastics on sulfur REDOX processes in different soil types: A mechanism study.

Microplastics can potentially affect the physical and chemical properties of soil, as well as soil microbial communities. This could, in turn, influence soil sulfur REDOX processes and the ability of soil to supply sulfur effectively. However, the specific mechanisms driving these effects remain unclear. To explore this, soil microcosm experiments were conducted to assess the impacts of polystyrene (PS) and polyphenylene sulfide (PPS) microplastics on sulfur reduction-oxidation (REDOX) processes in black, meadow, and paddy soils. The findings revealed that PS and PPS most significantly decreased SO42- in black soil by 9.4%, elevated SO42- in meadow soil by 20.8%, and increased S2- in paddy soil by 20.5%. PS and PPS microplastics impacted the oxidation process of sulfur in soil by influencing the activity of sulfur dioxygenase, which was mediated by α-proteobacteria and γ-proteobacteria, and the oxidation process was negatively influenced by soil organic matter. PS and PPS microplastics impacted the reduction process of sulfur in soil by influencing the activity of adenosine-5'-phosphosulfate reductase, sulfite reductase, which was mediated by Desulfuromonadales and Desulfarculales, and the reduction process was positively influenced by soil organic matter. In addition to their impacts on microorganisms, it was found that PP and PPS microplastics directly influenced the structure of soil enzymes, leading to alterations in soil enzyme activity. This study sheds light on the mechanisms by which microplastics impact soil sulfur REDOX processes, providing valuable insights into how microplastics influence soil health and functioning, which is essential for optimizing crop growth and maximizing yield in future agricultural practices.

Flexible, Transparent and Conductive Metal Mesh Films with Ultra-High FoM for Stretchable Heating and Electromagnetic Interference Shielding.

Despite the growing demand for transparent conductive films in smart and wearable electronics for electromagnetic interference (EMI) shielding, achieving a flexible EMI shielding film, while maintaining a high transmittance remains a significant challenge. Herein, a flexible, transparent, and conductive copper (Cu) metal mesh film for EMI shielding is fabricated by self-forming crackle template method and electroplating technique. The Cu mesh film shows an ultra-low sheet resistance (0.18 Ω â–¡-1), high transmittance (85.8%@550 nm), and ultra-high figure of merit (> 13,000). It also has satisfactory stretchability and mechanical stability, with a resistance increases of only 1.3% after 1,000 bending cycles. As a stretchable heater (ε > 30%), the saturation temperature of the film can reach over 110 °C within 60 s at 1.00 V applied voltage. Moreover, the metal mesh film exhibits outstanding average EMI shielding effectiveness of 40.4 dB in the X-band at the thickness of 2.5 µm. As a demonstration, it is used as a transparent window for shielding the wireless communication electromagnetic waves. Therefore, the flexible and transparent conductive Cu mesh film proposed in this work provides a promising candidate for the next-generation EMI shielding applications.