Identification of Potential TMPRSS2 Inhibitors for COVID-19 Treatment in Chinese Medicine by Computational Approaches and Surface Plasmon Resonance Technology.

BACKGROUND: Coronavirus disease-19 (COVID-19) pneumonia continues to spread in the entire globe with limited medication available. In this study, the active compounds in Chinese medicine (CM) recipes targeting the transmembrane serine protease 2 (TMPRSS2) protein for the treatment of COVID-19 were explored. METHODS: The conformational structure of TMPRSS2 protein (TMPS2) was built through homology modeling. A training set covering TMPS2 inhibitors and decoy molecules was docked to TMPS2, and their docking poses were re-scored with scoring schemes. A receiver operating characteristic (ROC) curve was applied to select the best scoring function. Virtual screening of the candidate compounds (CCDs) in the six highly effective CM recipes against TMPS2 was conducted based on the validated docking protocol. The potential CCDs after docking were subject to molecular dynamics (MD) simulations and surface plasmon resonance (SPR) experiment. RESULTS: A training set of 65 molecules were docked with modeled TMPS2 and LigScore2 with the highest area under the curve, AUC, value (0.886) after ROC analysis selected to best differentiate inhibitors from decoys. A total of 421 CCDs in the six recipes were successfully docked into TMPS2, and the top 16 CCDs with LigScore2 higher than the cutoff (4.995) were screened out. MD simulations revealed a stable binding between these CCDs and TMPS2 due to the negative binding free energy. Lastly, SPR experiments validated the direct combination of narirutin, saikosaponin B1, and rutin with TMPS2. CONCLUSIONS: Specific active compounds including narirutin, saikosaponin B1, and rutin in CM recipes potentially target and inhibit TMPS2, probably exerting a therapeutic effect on COVID-19.

Multiple detection of 13 kinds of viruses in 500 children with acute respiratory tract infection in Hami of Xinjiang province

OBJECTIVE: To investigate and analyze multiple detection of 13 kinds of viruses in 500 children with acute respiratory tract infection in Hami of Xinjiang. METHODS: A total of 500 children with acute respiratory tract infection treated in the hospital between Jan 2018 and Jan 2021 were enrolled. Thirteen kinds of respiratory infection viruses including human respiratory syncytial virus(RSV), human rhinovirus(hRV), respiratory adenovirus(AdV), influenza A and B viruses(Inf A, Inf B), parainfluenza virus(PIV 1/2/3), human enterovirus(hEV), human metapneumovirus(hMPV), human coronavirus(hCoV 229E/OC43) and human Boca virus(hBoV) were detected by multiple reverse transcription polymerase chain reaction(RT-PCR) amplification and capillary electrophoresis. And the results were compared with those by direct sequencing method. RESULTS: Of the 500 samples, 379 samples were positive(75.80%), and the top three detection rates were RSV(19.40%), hRV(16.00%) and Inf B(12.60%). The differences in positive rates of the respiratory virus among <1 year group, 1-3 years group and >3 years group were significant(84.97%, 77.47%, 65.45%)(P<0.05). The detection rate of RSV was the highest in <1 year group, and the detection rates of Inf A and Inf B were the highest in >3 years group. The differences in positive rates of respiratory viruses among the spring group, summer group, autumn group and winter group were significant(74.05%, 63.73%, 77.24%, 84.03%)(P<0.05). The detection rates of RSV, PIV 3, and hMPV were the highest in the winter group, and detection rate of AdV was the highest in spring group. CONCLUSION: RSV is the main infection virus in children with acute respiratory infection in Hami of Xinjiang. The distribution of respiratory viruses is related to age and onset season in children.

The city-wide full-scale interactive application of sewage surveillance programme for assisting real-time COVID-19 pandemic control - A case study in Hong Kong.

The paper discusses the implementation of Hong Kong's tailor-made sewage surveillance programme led by the Government, which has demonstrated how an efficient and well-organized sewage surveillance system can complement conventional epidemiological surveillance to facilitate the planning of intervention strategies and actions for combating COVID-19 pandemic in real-time. This included the setting up of a comprehensive sewerage network-based SARS-CoV-2 virus surveillance programme with 154 stationary sites covering 6 million people (or 80 % of the total population), and employing an intensive monitoring programme to take samples from each stationary site every 2 days. From 1 January to 22 May 2022, the daily confirmed case count started with 17 cases per day on 1 January to a maximum of 76,991 cases on 3 March and dropped to 237 cases on 22 May. During this period, a total of 270 "Restriction-Testing Declaration" (RTD) operations at high-risk residential areas were conducted based on the sewage virus testing results, where over 26,500 confirmed cases were detected with a majority being asymptomatic. In addition, Compulsory Testing Notices (CTN) were issued to residents, and the distribution of Rapid Antigen Test kits was adopted as alternatives to RTD operations in areas of moderate risk. These measures formulated a tiered and cost-effective approach to combat the disease in the local setting. Some ongoing and future enhancement efforts to improve efficacy are discussed from the perspective of wastewater-based epidemiology. Forecast models on case counts based on sewage virus testing results were also developed with R2 of 0.9669-0.9775, which estimated that up to 22 May 2022, around 2,000,000 people (~67 % higher than the total number of 1,200,000 reported to the health authority, due to various constraints or limitations) had potentially contracted the disease, which is believed to be reflecting the real situation occurring in a highly urbanized metropolis like Hong Kong.

Genomic evidence for divergent co-infections of co-circulating SARS-CoV-2 lineages.

Co-infection of RNA viruses may contribute to their recombination and cause severe clinical symptoms. However, the tracking and identification of SARS-CoV-2 co-infection persist as challenges. Due to the lack of methods for detecting co-infected samples in a large amount of deep sequencing data, the lineage composition, spatial-temporal distribution, and frequency of SARS-CoV-2 co-infection events in the population remains unclear. Here, we propose a hypergeometric distribution-based method named Cov2Coinfect with the ability to decode the lineage composition from 50,809 deep sequencing data. By resolving the mutational patterns in each sample, Cov2Coinfect can precisely determine the co-infected SARS-CoV-2 variants from deep sequencing data. Results from two independent and parallel projects in the United States achieved a similar co-infection rate of 0.3-0.5 % in SARS-CoV-2 positive samples. Notably, all co-infected variants were highly consistent with the co-circulating SARS-CoV-2 lineages in the regional epidemiology, demonstrating that the co-circulation of different variants is an essential prerequisite for co-infection. Overall, our study not only provides a robust method to identify the co-infected SARS-CoV-2 variants from sequencing samples, but also highlights the urgent need to pay more attention to co-infected patients for better disease prevention and control.

Simultaneous determination of twenty-nine active compounds in fuzhengjiedu granules by HPLC-QQQ-MS/MS.

As an empirical medicine of traditional Chinese medicine, Fuzhengjiedu Granules have shown an effect against COVID-19 in clinical and inflammatory animal models. It is formulated with eight herbs, including Aconiti Lateralis Radix Praeparata, Zingiberis Rhizoma, Glycyrrhizae Radix Et Rhizoma, Lonicerae Japonicae Flos, Gleditsiae Spina, Fici Radix, Pogostemonis Herba, and Citri Reticulatae Pericarpium. This study established a high-performance liquid chromatography-triple quadrupole mass spectrometry (HPLC-QQQ-MS/MS) method by simultaneously determining 29 active compounds in the granules with significant content differences. Separation by gradient elution using acetonitrile and water (0.1% formic acid) as mobile phases was performed on a Waters Acquilty UPLC T3 column (2.1 mm × 100 mm, 1.7 µm). A triple quadrupole mass spectrometer, operating in positive and negative ionization modes, was used for multiple reaction monitoring to detect the 29 compounds. All calibration curves showed good linear regression (r2 > 0.998). RSDs of precision, reproducibility, and stability of active compounds were all lower than 5.0%. The recovery rates were 95.4-104.9%, with RSDs< 5.0%. This method was successfully used to analyze the samples, and the results showed that 26 representative active components from 8 herbs were detected in the granules. While aconitine, mesaconitine, and hypaconitine were not detected, indicating that the existing samples were safe. The granules had the maximum and minimum content of hesperidin (27.3 ± 0.375 mg/g) and benzoylaconine (38.2 ± 0.759 ng/g). To conclude, a fast, accurate, sensitive, and reliable HPLC-QQQ-MS/MS method was established, which can simultaneously detect 29 active compounds that have a considerable difference in the content of Fuzhengjiedu Granules. This study can be used to control the quality and safety of Fuzhengjiedu Granules and provide a basis and guarantee for further experimental research and clinical application.

covSampler: A subsampling method with balanced genetic diversity for large-scale SARS-CoV-2 genome data sets.

Phylogenetic analysis has been widely used to describe, display, and infer the evolutionary patterns of viruses. The unprecedented accumulation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes has provided valuable materials for the real-time study of SARS-CoV-2 evolution. However, the large number of SARS-CoV-2 genome sequences also poses great challenges for data analysis. Several methods for subsampling these large data sets have been introduced. However, current methods mainly focus on the spatiotemporal distribution of genomes without considering their genetic diversity, which might lead to post-subsampling bias. In this study, a subsampling method named covSampler was developed for the subsampling of SARS-CoV-2 genomes with consideration of both their spatiotemporal distribution and their genetic diversity. First, covSampler clusters all genomes according to their spatiotemporal distribution and genetic variation into groups that we call divergent pathways. Then, based on these divergent pathways, two kinds of subsampling strategies, representative subsampling and comprehensive subsampling, were provided with adjustable parameters to meet different users' requirements. Our performance and validation tests indicate that covSampler is efficient and stable, with an abundance of options for user customization. Overall, our work has developed an easy-to-use tool and a webserver (https://www.covsampler.net) for the subsampling of SARS-CoV-2 genome sequences.

Dual ligand-induced photoelectrochemical sensing by integrating Pt/MoS2 heterostructure and Au polyhedra for sensitive detection of SARS-CoV-2.

The continuous evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with discovery of multiple mutants, has caused widespread panic and concern worldwide. The rapid antigen detection method via a single ligand recognition, although currently implemented in many countries, remains challenging for mutated antigens. Herein, we present a novel strategy using a dual recognition by two types of targeted ligands, based on photoelectrochemical (PEC) sensing for detection of SARS-CoV-2 spike protein. To demonstrate this strategy, the specific antibodies are modified onto the photoactive material with a supported nanostructure, created by loading the Pt nanoparticles onto MoS2 nanosheets (Pt/MoS2) to boost photon-to-electricity conversion efficiency. By subsequent binding of the targeted aptamers to the Au polyhedra, which act as a signal amplifier to suppress PEC photocurrent by competing with the Pt/MoS2 for the absorption of excitation light energy, the dual recognition is successfully achieved. The constructed biosensor not only shows satisfactory stability, high sensitivity, and selectivity, but is effective for test of the pseudovirus of SARS-CoV-2. The work provides useful advance for the development of PEC biosensors for sensitive detection of SARS-CoV-2.

Metabolic and Proteomic Profiles Associated with Immune Responses Induced by Different Inactivated SARS-CoV-2 Vaccine Candidates.

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019, the virus has been mutating continuously, resulting in the continuous emergence of variants and creating challenges for epidemic prevention and control. Here, we immunized mice with different vaccine candidates, revealing the immune, protein, and metabolomic changes that take place in vaccines composed of different variants. We found that the prototype strain and Delta- and Omicron-variant inactivated vaccine candidates could all induce a high level of neutralizing antibodies and cellular immunity responses in mice. Next, we found that the metabolic and protein profiles were changed, showing a positive association with immune responses, and the level of the change was distinct in different inactivated vaccines, indicating that amino acid variations could affect metabolomics and proteomics. Our findings reveal differences between vaccines at the metabolomic and proteomic levels. These insights provide a novel direction for the immune evaluation of vaccines and could be used to guide novel strategies for vaccine design.

covSampler: A Subsampling Method with Balanced Genetic Diversity for Large-Scale SARS-CoV-2 Genome Data Sets

Phylogenetic analysis has been widely used to describe, display and infer the evolutionary patterns of viruses. The unprecedented accumulation of SARS-CoV-2 genomes has provided valuable materials for the real-time study of SARS-CoV-2 evolution. However, the large number of SARS-CoV-2 genome sequences also poses great challenges for data analysis. Several methods for subsampling these large data sets have been introduced. However, current methods mainly focus on the spatiotemporal distribution of genomes without considering their genetic diversity, which might lead to postsubsampling bias. In this study, a subsampling method named covSampler was developed for the subsampling of SARS-CoV-2 genomes with consideration of both their spatiotemporal distribution and their genetic diversity. First, covSampler clusters all genomes according to their spatiotemporal distribution and genetic variation into groups that we call divergent pathways. Then, based on these divergent pathways, two kinds of subsampling strategies, representative subsampling and comprehensive subsampling, were provided with adjustable parameters to meet different users’ requirements. Our performance and validation tests indicate that covSampler is efficient and stable, with an abundance of options for user customization. Overall, our work has developed an easy-to-use tool and a webserver (https://www.covsampler.net) for the subsampling of SARS-CoV-2 genome sequences.

Alum/CpG Adjuvanted Inactivated COVID-19 Vaccine with Protective Efficacy against SARS-CoV-2 and Variants.

Since the beginning of the COVID-19 pandemic, numerous variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged, including five variants of concern (VOC) strains listed by the WHO: Alpha, Beta, Gamma, Delta and Omicron. Extensive studies have shown that most of these VOC strains, especially the currently dominant variant Omicron, can escape the host immune response induced by existing COVID-19 vaccines to different extents, which poses considerable risk to the health of human beings around the world. In the present study, we developed a vaccine based on inactivated SARS-CoV-2 and an adjuvant consisting of aluminum hydroxide (alum) and CpG. The immunogenicity and safety of the vaccine were investigated in rats. The candidate vaccine elicited high titers of SARS-CoV-2-spike-specific IgG antibody and neutralizing antibody in immunized rats, which not only neutralize the original SARS-CoV-2, but also showed great cross-neutralization activity against the Beta, Delta and Omicron variants.

Scorpion-Shaped Zinc Porphyrins as Tetrafunctional TAR RNA Predators and HIV-1 Reverse Transcriptase Inhibitors.

HIV-1 reverse transcriptase (RT) inhibitors are fundamental to the discovery and development of anti-HIV drugs. Their main target is RT, and only a tiny number of them can bind to viral RNA. In this paper, five new Zn(II) porphyrin compounds were developed with different characters. ZnTPP4 has both the appearance and the functions of a scorpion with a rigid tail and stinger to selectively hunt HIV-1 TAR RNA based on the molecular recognition of hydrogen bonds, a fierce chelicera to bite RNA by metal coordination, mighty pedipalps to grasp the bound RNA by supramolecular inclusion, and a broad body maintaining the configuration of each functional area so that they can cooperate with each other and providing accommodation space for the bound RNA. This tetrafunctional Zn(II) porphyrin is relatively nontoxic to normal cells and can produce sensitive responses for RNA. Moreover, this work offers practical construction methodologies for medication of AIDS and other diseases closely related to RT like EBOV and SARS-CoV-2.

Detecting Potentially Adaptive Mutations from the Parallel and Fixed Patterns in SARS-CoV-2 Evolution.

Early identification of adaptive mutations could provide timely help for the control and prevention of the COVID-19 pandemic. The fast accumulation of SARS-CoV-2 sequencing data provides important support, while also raising a great challenge for the recognition of adaptive mutations. Here, we proposed a computational strategy to detect potentially adaptive mutations from their fixed and parallel patterns in the phylogenetic trajectory. We found that the biological meanings of fixed substitution and parallel mutation are highly complementary, and can reasonably be integrated as a fixed and parallel (paraFix) mutation, to identify potentially adaptive mutations. Tracking the dynamic evolution of SARS-CoV-2, 37 sites in spike protein were identified as having experienced paraFix mutations. Interestingly, 70% (26/37) of them have already been experimentally confirmed as adaptive mutations. Moreover, most of the mutations could be inferred as paraFix mutations one month earlier than when they became regionally dominant. Overall, we believe that the concept of paraFix mutations will help researchers to identify potentially adaptive mutations quickly and accurately, which will provide invaluable clues for disease control and prevention.

Detecting Potentially Adaptive Mutations from the Parallel and Fixed Patterns in SARS-CoV-2 Evolution

Early identification of adaptive mutations could provide timely help for the control and prevention of the COVID-19 pandemic. The fast accumulation of SARS-CoV-2 sequencing data provides important support, while also raising a great challenge for the recognition of adaptive mutations. Here, we proposed a computational strategy to detect potentially adaptive mutations from their fixed and parallel patterns in the phylogenetic trajectory. We found that the biological meanings of fixed substitution and parallel mutation are highly complementary, and can reasonably be integrated as a fixed and parallel (paraFix) mutation, to identify potentially adaptive mutations. Tracking the dynamic evolution of SARS-CoV-2, 37 sites in spike protein were identified as having experienced paraFix mutations. Interestingly, 70% (26/37) of them have already been experimentally confirmed as adaptive mutations. Moreover, most of the mutations could be inferred as paraFix mutations one month earlier than when they became regionally dominant. Overall, we believe that the concept of paraFix mutations will help researchers to identify potentially adaptive mutations quickly and accurately, which will provide invaluable clues for disease control and prevention.

Evaluation of RT-qPCR Primer-Probe Sets to Inform Public Health Interventions Based on COVID-19 Sewage Tests.

Sewage surveillance is increasingly employed as a supplementary tool for COVID-19 control. Experiences learnt from large-scale trials could guide better interpretation of the sewage data for public health interventions. Here, we compared the performance of seven commonly used primer-probe sets in RT-qPCR and evaluated the usefulness in the sewage surveillance program in Hong Kong. All selected primer-probe sets reliably detected SARS-CoV-2 in pure water at 7 copies per µL. Sewage matrix did not influence RT-qPCR determination of SARS-CoV-2 concentrated from a small-volume sewage (30 mL) but introduced inhibitory impacts on a large-volume sewage (920 mL) with a ΔCt of 0.2-10.8. Diagnostic performance evaluation in finding COVID-19 cases showed that N1 was the best single primer-probe set, while the ORF1ab set is not recommended. Sewage surveillance using the N1 set for over 3200 samples effectively caught the outbreak trend and, importantly, had a 56% sensitivity and a 96% specificity in uncovering the signal sources from new cases and/or convalescent patients in the community. Our study paves the way for selecting detection primer-probe sets in wider applications in responding to the COVID-19 pandemic.

Genetic differentiation and diversity of SARS-CoV-2 Omicron variant in its early outbreak.

The recently emerged Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has quickly spread around the world. Although many consensus mutations of the Omicron variant have been recognized, little is known about its genetic variation during its transmission in the population. Here, we comprehensively analyzed the genetic differentiation and diversity of the Omicron variant during its early outbreak. We found that Omicron achieved more structural variations, especially deletions, on the SARS-CoV-2 genome than the other four variants of concern (Alpha, Beta, Gamma, and Delta) in the same timescale. In addition, the Omicron variant acquired, except for 50 consensus mutations, seven great new non-synonymous nucleotide substitutions during its spread. Three of them are on the S protein, including S_A701V, S_L1081V, and S_R346K, which belong to the receptor-binding domain (RBD). The Omicron BA.1 branch could be divided into five divergent groups spreading across different countries and regions based on these seven novel mutations. Furthermore, we found that the Omicron variant possesses more mutations related to a faster transmission rate than the other SARS-CoV-2 variants by assessing the relationship between the genetic diversity and transmission rate. The findings indicated that more attention should be paid to the significant genetic differentiation and diversity of the Omicron variant for better disease prevention and control.

Conserved Pattern and Potential Role of Recurrent Deletions in SARS-CoV-2 Evolution.

SARS-CoV-2 continues adapting to human hosts during the current worldwide pandemic since 2019. This virus evolves through multiple means, such as single nucleotide mutations and structural variations, which has brought great difficulty to disease prevention and control of COVID-19. Structural variation, including multiple nucleotide changes like insertions and deletions, has a greater impact relative to single nucleotide mutation on both genome structures and protein functions. In this study, we found that deletion occurred frequently in not only SARS-CoV-2 but also in other SARS-related coronaviruses. These deletions showed obvious location bias and formed 45 recurrent deletion regions in the viral genome. Some of these deletions showed proliferation advantages, including four high-frequency deletions (nsp6 Δ106-109, S Δ69-70, S Δ144, and Δ28271) that were detected in around 50% of SARS-CoV-2 genomes and other 19 median-frequency deletions. In addition, the association between deletions and the WHO reported variants of concern (VOC) and variants of interest (VOI) of SARS-CoV-2 indicated that these variants had a unique combination of deletion patterns. In the spike (S) protein, the deletions in SARS-CoV-2 were mainly in the N-terminal domain. Some deletions, such as S Δ144/145 and S Δ243-244, have been confirmed to block the binding sites of neutralizing antibodies. Overall, this study revealed a conservative regional pattern and the potential effect of some deletions in SARS-CoV-2 over the whole genome, providing important evidence for potential epidemic control and vaccine development. IMPORTANCE Mutations in SARS-CoV-2 were studied extensively, while only the structure variations on the spike protein were discussed well in previous studies. To study the role of structural variations in virus evolution, we described the distribution of structure variations on the whole genome. Conserved patterns were found of deletions among SARS-CoV-2, SARS-CoV-2-like, and SARS-CoV-like viruses. There were 45 recurrent deletion regions (RDRs) in SARS-CoV-2 generated through the integration of deleted positions. In these regions, four high-frequency deletions parallelly appeared in multiple strains. Furthermore, in the spike protein, the deletions in SARS-CoV-2 were mainly in the N-terminal domain, blocking the binding sites of some neutralizing antibodies, while the structural variations in SARS-related coronavirus were mainly in the N-terminal domain and receptor binding domain. The receptor binding domain is highly related to hosting recognition. The deletions in the receptor binding domain may play a role in host adaption.

An imidazolium-based zwitterionic polymer for antiviral and antibacterial dual functional coatings.

To reduce the severe health risk and the huge economic impact associated with the fomite transmission of SARS-CoV-2, an imidazolium-based zwitterionic polymer was designed, synthesized, and demonstrated to achieve contact deactivation of a human coronavirus under dry ambient conditions that resemble fomite transmission. The zwitterionic polymer further demonstrated excellent antifouling properties, reducing the adhesion of coronavirus and the formation of bacteria biofilms under wetted conditions. The polymer was synthesized using a substrate-independent and solvent-free process, leveraging an all-dry technique named initiated chemical vapor deposition (iCVD). The broad applicability of this approach was demonstrated by applying the polymer to a range of substrates that are curved and/or with high-aspect-ratio nano/microporous structures, which remained intact after the coating process. The zwitterionic polymer and the synthesis approach reported here present an effective solution to mitigate viral transmission without the need for manual disinfection, reducing the health and economic impact of the ongoing pandemic.

Impact of near-surface turbulence on PM2.5 concentration in Chengdu during the COVID-19 pandemic.

The role of meteorological conditions has long been recognized in modulating regional air quality. The impact of near-surface turbulence, nevertheless, remains poorly understood. To curb the spread of COVID-19, a variety of lockdown measures were implemented, providing us an unprecedented opportunity to examine the joint impact of emission control and meteorology on regional air quality. Here we examined the variations of planetary boundary layer (PBL) height, PM2.5 concentrations, turbulence kinetic energy (TKE), vertical wind shear, and their associations in Chengdu, Sichuan province in Southwest China between January 13 and February 24, 2020, by synergistically using micro pulse lidar, ground-level meteorological and PM2.5 measurements, as well as ultrasonic anemometer observations. During the study period, Sichuan basin was primarily regulated by the straight west wind, with an averaged wind speed of 2-3 m/s at 850 hPa, indicative of a relatively stable atmospheric dispersion condition. TKE was positively correlated with PBL height but negatively correlated with PM2.5. The PM2.5 concentration varied dramatically during pre- and post-lockdown periods but remained near constant at a relatively low level during the lockdown period. Meanwhile, the negative correlation between TKE and PM2.5 was much stronger during the lockdown and post-lockdown periods, when aerosol emissions were significantly reduced. Moreover, the correlation between TKE and PM2.5 exhibited large diurnal variability, with the strongest correlation observed during the daytime when solar radiation and turbulent mixing generally reached their peaks. Overall, the observational results in Chengdu underscore the non-negligible impact of turbulence on regional PM2.5 concentrations, which could help better understand the variation of regional air pollution events.

Recombinant angiopoietin-like protein 4 attenuates intestinal barrier structure and function injury after ischemia/reperfusion.

BACKGROUND: Intestinal barrier breakdown, a frequent complication of intestinal ischemia-reperfusion (I/R) including dysfunction and the structure changes of the intestine, is characterized by a loss of tight junction and enhanced permeability of the intestinal barrier and increased mortality. To develop effective and novel therapeutics is important for the improvement of outcome of patients with intestinal barrier deterioration. Recombinant human angiopoietin-like protein 4 (rhANGPTL4) is reported to protect the blood-brain barrier when administered exogenously, and endogenous ANGPTL4 deficiency deteriorates radiation-induced intestinal injury. AIM: To identify whether rhANGPTL4 may protect intestinal barrier breakdown induced by I/R. METHODS: Intestinal I/R injury was elicited through clamping the superior mesenteric artery for 60 min followed by 240 min reperfusion. Intestinal epithelial (Caco-2) cells and human umbilical vein endothelial cells were challenged by hypoxia/ reoxygenation to mimic I/R in vitro. RESULTS: Indicators including fluorescein isothiocyanate-conjugated dextran (4 kilodaltons; FD-4) clearance, ratio of phosphorylated myosin light chain/total myosin light chain, myosin light chain kinase and loss of zonula occludens-1, claudin-2 and VE-cadherin were significantly increased after intestinal I/R or cell hypoxia/reoxygenation. rhANGPTL4 treatment significantly reversed these indicators, which were associated with inhibiting the inflammatory and oxidative cascade, excessive activation of cellular autophagy and apoptosis and improvement of survival rate. Similar results were observed in vitro when cells were challenged by hypoxia/reoxygenation, whereas rhANGPTL4 reversed the indicators close to normal level in Caco-2 cells and human umbilical vein endothelial cells significantly. CONCLUSION: rhANGPTL4 can function as a protective agent against intestinal injury induced by intestinal I/R and improve survival via maintenance of intestinal barrier structure and functions.

Porous Au@Pt nanoparticles with superior peroxidase-like activity for colorimetric detection of spike protein of SARS-CoV-2.

The development of colorimetric assays for rapid and accurate diagnosis of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is of practical importance for point-of-care (POC) testing. Here we report the colorimetric detection of spike (S1) protein of SARS-CoV-2 based on excellent peroxidase-like activity of Au@Pt nanoparticles, with merits of rapidness, easy operation, and high sensitivity. The Au@Pt NPs were fabricated by a facile seed-mediated growth approach, in which spherical Au NPs were premade as seeds, followed by the Pt growth on Au seeds, producing uniform, monodispersed and porous Au@Pt core-shell NPs. The as-obtained Au@Pt NPs showed a remarkable enhancement in the peroxidase-mimic catalysis, which well abided by the typical Michaelis-Menten theory. The enhanced catalysis of Au@Pt NPs was ascribed to the porous nanostructure and formed electron-rich Pt shells, which enabled the catalytic pathway to switch from hydroxyl radical generation to electron transfer process. On a basis of these findings, a colorimetric assay of spike (S1) protein of SARS-CoV-2 was established, with a linear detection range of 10-100 ng mL-1 of protein concentration and a low limit of detection (LOD) of 11 ng mL-1. The work presents a novel strategy for diagnosis of COVID-19 based on metallic nanozyme-catalysis.