SARS-CoV-2 Delta and Omicron variants evade population antibody response by mutations in a single spike epitope

Population antibody response is thought to be important in selection of virus variants. We report that SARS-CoV-2 infection elicits a population immune response that is mediated by a lineage of VH1-69 germline antibodies. A representative antibody R1-32 from this lineage was isolated. By cryo-EM, we show that it targets a semi-cryptic epitope in the spike receptor-binding domain. Binding to this non-ACE2 competing epitope results in spike destruction, thereby inhibiting virus entry. On the basis of epitope location, neutralization mechanism and analysis of antibody binding to spike variants, we propose that recurrent substitutions at 452 and 490 are associated with immune evasion of the identified population antibody response. These substitutions, including L452R (present in the Delta variant), disrupt interactions mediated by the VH1-69-specific hydrophobic HCDR2 to impair antibody-antigen association, enabling variants to escape. The first Omicron variants were sensitive to antibody R1-32 but subvariants that harbour L452R quickly emerged and spread. Our results provide insights into how SARS-CoV-2 variants emerge and evade host immune responses.

Characterization of Genetic Variants Associated with Rifampicin Resistance Level in Mycobacterium tuberculosis Clinical Isolates Collected in Guangzhou Chest Hospital, China

Objective

Rifampicin (RIF)-resistance, a surrogate marker for multidrug-resistant tuberculosis (TB), is mediated by mutations in the rpoB gene. We aimed to investigate the prevalence of mutations pattern in the entire rpoB gene of Mycobacterium tuberculosis clinical isolates and their association with resistance level to RIF.

Methods

Among 465 clinical isolates collected from the Guangzhou Chest Hospital, drug-susceptibility of 175 confirmed Mtb strains was performed via the proportion method and Bactec MGIT 960 system. GeneXpert MTB/RIF and sanger sequencing facilitated in genetic characterization, whereas the MICs of RIF were determined by Alamar blue assay.

Results

We found 150/175 (85.71%) RIF-resistant strains (MIC: 4 to >64 µg/mL) of which 57 were MDR and 81 pre-XDR TB. Genetic analysis identified 17 types of mutations 146/150 (97.33%) within RRDR (codons 426–452) of rpoB, mainly at L430 (P), D435 (V, E, G, N), H445 (N, D, Y, R, L), S450 (L, F) and L452 (P). D435V 12/146 (8.2%), H445N 16/146 (10.9%), and S450L 70/146 (47.94%) were the most frequently encountered mutations. Mutations Q432K, M434V, and N437D are rarely identified in RRDR. Deletions at (1284–1289 CCAGCT), (1295–1303 AATTCATGG), and insertion at (1300–1302 TTC) were detected within RRDR of three RIF^R strains for the first time. We detected 47 types of mutations and insertions/deletions (indels) outside the RRDR. Four RIF^R strains were detected with only novel mutations/indels outside the RRDR. Two of the four had (K274Q + C897 del + I491M) and (A286V + L494P), respectively. The other two had (G1687del + P454L) and (TT1835-6 ins + I491L) individually. Compared with phenotypic characterization, diagnostic sensitivities of GeneXpert MTB/RIF and sequencing analysis were 95.33% (143/150), and 100% (150/150) respectively.

Conclusion

Our findings underscore the key role of RRDR mutations and the contribution of non-RRDR mutations in rapid molecular diagnosis of RIF^R clinical isolates. Such insights will support early detection of disease and recommend the appropriate anti-TB regimens in high-burden settings.

A Class of Shark-Derived Single-Domain Antibodies can Broadly Neutralize SARS-Related Coronaviruses and the Structural Basis of Neutralization and Omicron Escape

The identification of a novel class of shark-derived single domain antibodies, named vnarbodies that show picomolar affinities binding to the receptor binding domain (RBD) of Wuhan and Alpha, Beta, Kappa, Delta, Delta-plus, and Lambda variants, is reported. Vnarbody 20G6 and 17F6 have broad neutralizing activities against all these SARS-CoV-2 viruses as well as other sarbecoviruses, including Pangolin coronavirus and Bat coronavirus. Intranasal administration of 20G6 effectively protects mice from the challenges of SARS-CoV-2 Wuhan and Beta variants. 20G6 and 17F6 contain a unique "WXGY" motif in the complementary determining region 3 that binds to a hidden epitope on RBD, which is highly conserved in sarbecoviruses through a novel β-sheet interaction. It is found that the S375F mutation on Omicron RBD disrupts the structure of β-strand, thus impair the binding with 20G6. The study demonstrates that shark-derived vnarbodies offer a prophylactic and therapeutic option against most SARS-CoV-2 variants and provide insights into antibody evasion by the Omicron variant.

Engineered disulfide reveals structural dynamics of locked SARS-CoV-2 spike

The spike (S) protein of SARS-CoV-2 has been observed in three distinct pre-fusion conformations: locked, closed and open. Of these, the function of the locked conformation remains poorly understood. Here we engineered a SARS-CoV-2 S protein construct “S-R/x3” to arrest SARS-CoV-2 spikes in the locked conformation by a disulfide bond. Using this construct we determined high-resolution structures confirming that the x3 disulfide bond has the ability to stabilize the otherwise transient locked conformations. Structural analyses reveal that wild-type SARS-CoV-2 spike can adopt two distinct locked-1 and locked-2 conformations. For the D614G spike, based on which all variants of concern were evolved, only the locked-2 conformation was observed. Analysis of the structures suggests that rigidified domain D in the locked conformations interacts with the hinge to domain C and thereby restrains RBD movement. Structural change in domain D correlates with spike conformational change. We propose that the locked-1 and locked-2 conformations of S are present in the acidic high-lipid cellular compartments during virus assembly and egress. In this model, release of the virion into the neutral pH extracellular space would favour transition to the closed or open conformations. The dynamics of this transition can be altered by mutations that modulate domain D structure, as is the case for the D614G mutation, leading to changes in viral fitness. The S-R/x3 construct provides a tool for the further structural and functional characterization of the locked conformations of S, as well as how sequence changes might alter S assembly and regulation of receptor binding domain dynamics.

Spike (S) proteins on the surface of SARS-CoV-2 initiate viral infection by binding to cell receptors and mediating the fusion of virus and cell membranes. Several conformations of S have been identified that are thought to exist at different steps of the virus life cycle, for example assembly, receptor-binding and entry. The function of a conformation termed “locked” has not been clearly understood, due to its transience. Here, we engineered a disulfide bond in SARS-CoV-2 S to stabilise the locked conformation for structural and biochemical studies. This allowed us to distinguish two distinct locked-1 and locked-2 conformations in S from the initial SARS-CoV-2 strain, only the locked-2 conformation still exists after introduction of the D614G mutation. Based on structural and biochemical characterizations, we propose that the locked conformations of S prevent the premature opening of the receptor binding domain during virus assembly and egress through intracellular compartments. Our engineered S provides a useful tool to facilitate structural research, serological research, and design of immunogens.

Microplasma-assisted synthesis of mixed-valence Ce-MOF with enhanced oxidase-like activity for colorimetric sensing of dopamine

Due to the high catalytic activity, stability and low cost, nanozymes with oxidase-like activity have attracted widespread interest in the fields of analytical detection and colorimetric sensing. To further promote...

Vulnerability and resilience in children during the COVID-19 pandemic

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic is having a profound impact on the health and development of children worldwide. There is limited evidence on the impact of COVID-19 and its related school closures and disease-containment measures on the psychosocial wellbeing of children; little research has been done on the characteristics of vulnerable groups and factors that promote resilience.

METHODS

We conducted a large-scale cross-sectional population study of Hong Kong families with children aged 2-12 years. Parents completed an online survey on family demographics, child psychosocial wellbeing, functioning and lifestyle habits, parent-child interactions, and parental stress during school closures due to COVID-19. We used simple and multiple linear regression analyses to explore factors associated with child psychosocial problems and parental stress during the pandemic.

RESULTS

The study included 29,202 individual families; of which 12,163 had children aged 2-5 years and 17,029 had children aged 6-12 years. The risk of child psychosocial problems was higher in children with special educational needs, and/or acute or chronic disease, mothers with mental illness, single-parent families, and low-income families. Delayed bedtime and/or inadequate sleep or exercise duration, extended use of electronic devices were associated with significantly higher parental stress and more psychosocial problems among pre-schoolers.

CONCLUSIONS

This study identifies vulnerable groups of children and highlights the importance of strengthening family coherence, adequate sleep and exercise, and responsible use of electronic devices in promoting psychosocial wellbeing during the COVID-19 pandemic.

Malignant acanthosis nigricans and diseases with extensive oral papillary hyperplasia

Oral papillary lesions represent a variety of developmental and neoplastic conditions. Early diagnoses of different papillary lesions are challenging for oral medicine specialists. Malignant acanthosis nigricans (MAN) is a rare cutaneous disorder and a potential marker of underlying hidden tumours. It is characterized by papillary lesions that always involve the oral mucosa. In oral medicine specialities, MAN is not well understood. When the early signs of MAN are extensive oral lesions and slight cutaneous pigmentation without obvious florid cutaneous papillomatosis, the diagnosis can be incorrect or delayed. Oral medicine specialists should ask affected patients to provide details of their medical history and conduct a timely systemic examination.

Multilevel Factors Affecting Healthcare Workers' Perceived Stress and Risk of Infection During COVID-19 Pandemic

Objectives: This study aimed to identify key factors affecting Healthcare workers (HCWs) perceived stress and risk of contracting COVID-19 among themselves and their family members during the pandemic. Methods: A cross-sectional online questionnaire study was conducted between 19 March and April 5, 2020 in Hong Kong. HCWs from public hospitals and private dentists, and their family members participated. Results: A total of 747 HCWs and 245 family members participated. Higher perceived stress in HCWs was associated with more negative changes in family relationship (p = 0.025). The HCWs' perceived stress, however, was positively associated with family cohesion (p = 0.033) and stress levels of family members (p < 0.001). The level of HCWs' satisfaction toward the hospital policies in response to the COVID-19 outbreak was associated with lower levels of perceived stress and risk of themselves or their family members contracting COVID-19. HCWs' previous frontline experience of SARS was significantly associated with less perceived risk of themselves or their family members contracting COVID-19. Conclusion: Hospital policies addressing HCWs' needs, frontline experience of SARS, and family relationship influenced psychological wellbeing of HCWs during the COVID-19 outbreak.

Transcriptome analysis of oviduct in laying ducks under different stocking densities

1. High stocking densities can lead to animal stress responses and lead to changes in bird behaviour, egg production and the fertility of laying birds. The oviduct plays a crucial role during the process of laying eggs. Therefore, it is essential to know how high stocking density affects oviduct function.2. In this study, a total of 2,115 differentially expressed genes (DEGs) were identified in duck oviduct tissues between different stocking density groups. These genes are mainly enriched in membrane components, calcium ion binding, cytokine-cytokine receptor interaction and focal adhesion. These pathways were closely related to the formation of eggs. This indicated that secretion and material transport functions of the oviduct are affected under high-density stocking. Further analysis showed that a total of 408 genes related to the transportation process were expressed in the oviduct, of which 96 genes were differentially expressed (LogFC≥1, P < 0.05). Forty-two of these DEGs belonged to the solute carrier family. The data showed that the expression of 31 transcripts was different between the two density groups. Expression of KCNJ15, SLC26A8, and TRPM5 was only seen in the high-density group (8/m²), while ATP13A3 and KCNIP2 were only expressed in the low-density group (4/m²).3. Consequently, high stocking density may affect the expression and splicing of genes related to molecular transport in the oviduct.

Hemagglutinin Structure and Activities

Hemagglutinins (HAs) are the receptor-binding and membrane fusion glycoproteins of influenza viruses. They recognize sialic acid-containing, cell-surface glycoconjugates as receptors but have limited affinity for them, and, as a consequence, virus attachment to cells requires their interaction with several virus HAs. Receptor-bound virus is transferred into endosomes where membrane fusion by HAs is activated at pH between 5 and 6.5, depending on the strain of virus. Fusion activity requires extensive rearrangements in HA conformation that include extrusion of a buried "fusion peptide" to connect with the endosomal membrane, form a bridge to the virus membrane, and eventually bring both membranes close together. In this review, we give an overview of the structures of the 16 genetically and antigenically distinct subtypes of influenza A HA in relation to these two functions in virus replication and in relation to recognition of HA by antibodies that neutralize infection.

New structural insights into the multifunctional influenza A matrix protein 1

Influenza A virus matrix protein 1 (M1) is the most abundant protein within virions and functions at multiple steps of the virus life cycle, including nuclear RNA export, virus particle assembly, and virus disassembly. Two recent publications have presented the first structures of full‐length M1 and show that it assembles filaments in vitro via an interface between the N‐ and C‐terminal domains of adjacent monomers. These filaments were found to be similar to those that form the endoskeleton of assembled virions. The structures provide a molecular basis to understand the functions of M1 during the virus life cycle. Here, we compare and discuss the two structures, and explore their implications for the mechanisms by which the multifunctional M1 protein can mediate virus assembly, interact with viral ribonucleoproteins and act during infection of a new cell.

[Analysis of related factors of poor prognosis in children with parenteral nutrition-associated cholestasis]

OBJECTIVE

To explore the related factors affecting the prognosis of children with parenteral nutrition-associated cholestasis (PNAC).

METHODS

Twenty children with PNAC admitted to Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science and Technology from January 2014 to December 2020 were selected as research objects by retrospective study. According to prognosis,children were divided into good (15 cases) and poor prognosis group (5 cases). Clinical data such as general condition, intravenous nutrition duration, related biochemical examination indexes and main treatment methods of children in the two groups were collected. Spearman correlation analysis was used to quantify the correlation between alanine aminotransferase (ALT) and poor prognosis. Univariate analysis was used to analyze the risk factors affecting the prognosis of children with PNAC, and receiver operating characteristic curve (ROC curve) was drawn to evaluate the predictive value of ALT on the prognosis of children.

RESULTS

There were no significant differences in gender, body weight, gestational age, age, feeding mode, duration of intravenous nutrition, direct bilirubin (DBil), aspartate aminotransferase (AST), γ-glutamyltranspeptidase (GGT), total protein (TP), serum albumin (Alb), globulin (GLB), alkaline phosphatase (ALP), platelet count (PLT), white blood cell count (WBC), red blood cell count (RBC), hemoglobin (Hb), lymphocyte count (LYM), urine culture, AST/PLT ratio (APRI) and main treatment methods between the two groups. Total bilirubin (TBil), ALT, neutrophil count (NEU) and monocyte count (MONO) in the good prognosis group were significantly lower than those in the poor prognosis group [TBil (μmol/L): 120.00±48.63 vs. 175.26±29.14, ALT (U/L): 73.25±44.29 vs. 145.30±74.33, NEU (×10⁹/L): 2.55±1.29 vs. 5.08±4.10, MONO (×10⁹/L): 1.23±0.87 vs. 2.13±0.60, all P < 0.05]. Logistic regression analysis showed that ALT was the risk factor affecting the prognosis of children with PNAC, when ALT increased by 1 U/L, the probability of poor prognosis increased by 3.6% [odds ratio (OR) = 1.04, 95% confidence interval (95%CI) was 1.00-1.07, P = 0.04]. Spearman correlation analysis showed that the incidence of poor prognosis was positively correlated with ALT (r = 0.49, P = 0.03). ROC analysis showed that ALT had certain predictive value for the prognosis of children with PNAC [area under ROC cure (AUC) = 0.83, 95%CI was 0.00-1.00, P = 0.03]; when the cut-off value was 121.50 U/L, its sensitivity was 80% and specificity was 93%, suggesting that ALT could be used as the main indicator for clinical prediction of poor prognosis for PNAC.

CONCLUSIONS

ALT is an independent risk factor of poor prognosis in children with PNAC.

SARS-CoV-2 Spike Protein Stabilized in the Closed State Induces Potent Neutralizing Responses

The majority of SARS-CoV-2 vaccines in use or advanced development are based on the viral spike protein (S) as their immunogen. S is present on virions as prefusion trimers in which the receptor binding domain (RBD) is stochastically open or closed. Neutralizing antibodies have been described against both open and closed conformations. The long-term success of vaccination strategies depends upon inducing antibodies that provide long-lasting broad immunity against evolving SARS-CoV-2 strains. Here, we have assessed the results of immunization in a mouse model using an S protein trimer stabilized in the closed state to prevent full exposure of the receptor binding site and therefore interaction with the receptor. We compared this with other modified S protein constructs, including representatives used in current vaccines. We found that all trimeric S proteins induced a T cell response and long-lived, strongly neutralizing antibody responses against 2019 SARS-CoV-2 and variants of concern P.1 and B.1.351. Notably, the protein binding properties of sera induced by the closed spike differed from those induced by standard S protein constructs. Closed S proteins induced more potent neutralizing responses than expected based on the degree to which they inhibit interactions between the RBD and ACE2. These observations suggest that closed spikes recruit different, but equally potent, immune responses than open spikes and that this is likely to include neutralizing antibodies against conformational epitopes present in the closed conformation. We suggest that closed spikes, together with their improved stability and storage properties, may be a valuable component of refined, next-generation vaccines. IMPORTANCE Vaccines in use against SARS-CoV-2 induce immune responses against the spike protein. There is intense interest in whether the antibody response induced by vaccines will be robust against new variants, as well as in next-generation vaccines for use in previously infected or immunized individuals. We assessed the use as an immunogen of a spike protein engineered to be conformationally stabilized in the closed state where the receptor binding site is occluded. Despite occlusion of the receptor binding site, the spike induces potently neutralizing sera against multiple SARS-CoV-2 variants. Antibodies are raised against a different pattern of epitopes to those induced by other spike constructs, preferring conformational epitopes present in the closed conformation. Closed spikes, or mRNA vaccines based on their sequence, can be a valuable component of next-generation vaccines.

An assessment of the mental health of front-line medical staff involved in the COVID-19 outbreak in Chongqing, China

In response to the coronavirus disease 2019 (COVID-19) outbreak in December 2019 in China, medical staff went to work across the country to combat widespread infection. When health workers are suddenly faced with such a serious event, it is important to assess their mental health in order to determine whether they can meet the challenge effectively. Herein, Symptom Checklist-90 (SCL-90) was used to assess the psychological problems of 382 front-line medical staff in Chongqing. The average SCL-90 score was low, and no specific mental health problems were found. With the exception of the phobic-anxiety factor, the scores were close to normal values. A single-factor analysis of variance showed that the SCL-90 scores of male and older staff were higher than those of female and younger staff, implying that they were at greater psychological risk. We found that both gender and age have a significant impact on mental health, and our findings suggest that more attention should be given to the mental health of male and older front-line medical staff.

Germline IGHV3-53-encoded RBD-targeting neutralizing antibodies are commonly present in the antibody repertoires of COVID-19 patients

Monoclonal antibodies (mAbs) encoded by IGHV3-53 (VH3-53) targeting the spike receptor-binding domain (RBD) have been isolated from different COVID-19 patients. However, the existence and prevalence of shared VH3-53-encoded antibodies in the antibody repertoires is not clear. Using antibody repertoire sequencing, we found that the usage of VH3-53 increased after SARS-CoV-2 infection. A highly shared VH3-53-J6 clonotype was identified in 9 out of 13 COVID-19 patients. This clonotype was derived from convergent gene rearrangements with few somatic hypermutations and was evolutionary conserved. We synthesized 34 repertoire-deduced novel VH3-53-J6 heavy chains and paired with a common IGKV1-9 light chain to produce recombinant mAbs. Most of these recombinant mAbs (23/34) possess RBD binding and virus-neutralizing activities, and recognize ACE2 binding site via the same molecular interface. Our computational analysis, validated by laboratory experiments, revealed that VH3-53 antibodies targeting RBD are commonly present in COVID-19 patients’ antibody repertoires, indicating many people have germline-like precursor sequences to rapidly generate SARS-CoV-2 neutralizing antibodies. Moreover, antigen-specific mAbs can be digitally obtained through antibody repertoire sequencing and computational analysis.

Hemagglutinin Traits Determine Transmission of Avian A/H10N7 Influenza Virus between Mammals

In 2014, an outbreak of avian A/H10N7 influenza virus occurred among seals along North-European coastal waters, significantly impacting seal populations. Here, we examine the cross-species transmission and mammalian adaptation of this influenza A virus, revealing changes in the hemagglutinin surface protein that increase stability and receptor binding. The seal A/H10N7 virus was aerosol or respiratory droplet transmissible between ferrets. Compared with avian H10 hemagglutinin, seal H10 hemagglutinin showed stronger binding to the human-type sialic acid receptor, with preferential binding to α2,6-linked sialic acids on long extended branches. In X-ray structures, changes in the 220-loop of the receptor-binding pocket caused similar interactions with human receptor as seen for pandemic strains. Two substitutions made seal H10 hemagglutinin more stable than avian H10 hemagglutinin and similar to human hemagglutinin. Consequently, identification of avian-origin influenza viruses across mammals appears critical to detect influenza A viruses posing a major threat to humans and other mammals.

[Establishment of naive Bayes classifier-based risk prediction model for chemotherapyinduced nausea and vomiting]

OBJECTIVE

To establish a risk prediction model of chemotherapy-induced nausea and vomiting based on naive Bayes classifier.

OBJECTIVE

We collected the basic information, treatment protocols and follow-up data from 300 patients receiving chemotherapy in the Oncology Department of Second Xiangya Hospital from July to September, 2020. Correlation analysis was carried out between the potential factors related to nausea and vomiting in the treatment plan and the individual characteristics of the patients. For the two characteristics with a correlation coefficient greater than 0.8, their contribution to the area under curve (AUC) was calculated, and the characteristic with a smaller contribution was removed. The naive Bayes classifier in the machine learning library scikit-learn was used as the prediction model of chemotherapy-induced nausea and vomiting, and 10-fold stratified-shuffled-split cross-validation was used to obtain the final result of the model. The machine learning model was trained using 70% of the samples, and 30% of the samples were used as the test set to assess the performance of the model.

OBJECTIVE

The sensitivity of the model for predicting the risk of nausea and vomiting due to acute chemotherapy was 0.83±0.04 (95%CI: 0.80-0.86) with a specificity of 0.45±0.03 (95%CI: 0.42-0.47) and an AUC of 0.72±0.04 (95% CI: 0.69-0.75). The sensitivity of the model for predicting the risk of delayed chemotherapy-induced nausea and vomiting was 0.84±0.01 (95%CI: 0.83-0.86) with a specificity of 0.48±0.03 (95%CI: 0.45-0.52) and an AUC of 0.74±0.02 (95%CI: 0.72-0.77).

OBJECTIVE

The naive Bayes classifier model has a good performance in predicting the risk of chemotherapy-induced nausea and vomiting in Chinese cancer patients.

Structural basis for broad coronavirus neutralization

Three highly pathogenic β-coronaviruses crossed the animal-to-human species barrier in the past two decades: SARS-CoV, MERS-CoV and SARS-CoV-2. SARS-CoV-2 has infected more than 64 million people worldwide, claimed over 1.4 million lives and is responsible for the ongoing COVID-19 pandemic. We isolated a monoclonal antibody, termed B6, cross-reacting with eight β-coronavirus spike glycoproteins, including all five human-infecting β-coronaviruses, and broadly inhibiting entry of pseudotyped viruses from two coronavirus lineages. Cryo-electron microscopy and X-ray crystallography characterization reveal that B6 binds to a conserved cryptic epitope located in the fusion machinery and indicate that antibody binding sterically interferes with spike conformational changes leading to membrane fusion. Our data provide a structural framework explaining B6 cross-reactivity with β-coronaviruses from three lineages along with proof-of-concept for antibody-mediated broad coronavirus neutralization elicited through vaccination. This study unveils an unexpected target for next-generation structure-guided design of a pan-coronavirus vaccine.

COVID-19 in children across three Asian cosmopolitan regions

As another wave of COVID-19 outbreak has approached in July 2020, a larger scale COVID-19 pediatric Asian cohort summarizing the clinical observations is warranted. Children confirmed with COVID-19 infection from the Republic of Korea, the Hong Kong Special Administrative Region (HKSAR) and Wuhan, China, during their first waves of local outbreaks were included. Their clinical characteristics and the temporal sequences of the first waves of local paediatric outbreaks were compared. Four hundred and twenty three children with COVID-19 were analyzed. Wuhan had the earliest peak, followed by Korea and HKSAR. Compared with Korea and Wuhan, patients in HKSAR were significantly older (mean age: 12.9 vs. 10.8 vs. 6.6 years, p < 0.001, respectively) and had more imported cases (87.5% vs. 16.5% vs. 0%, p < 0.001, respectively). The imported cases were also older (13.4 vs. 7.6 years, p < 0.001). More cases in HKSAR were asymptomatic compared to Korea and Wuhan (45.5% vs. 22.0% vs. 20.9%, p < 0.001, respectively), and significantly more patients from Wuhan developed fever (40.6% vs. 29.7% vs. 21.6%, p=0.003, respectively). There were significantly less imported cases than domestic cases developing fever after adjusting for age and region of origin (p = 0.046). 5.4% to 10.8% of patients reported anosmia and ageusia. None developed pediatric multisystem inflammatory syndrome temporally associated with SARS-CoV-2 (PMIS-TS). In general, adolescents were more likely to be asymptomatic and less likely to develop fever, but required longer hospital stays. In conclusion, majority patients in this pediatric Asian cohort had a mild disease. None developed PIMS-TS. Their clinical characteristics were influenced by travel history and age.

A thermostable, closed SARS-CoV-2 spike protein trimer

The spike (S) protein of SARS-CoV-2 mediates receptor binding and cell entry and is the dominant target of the immune system. It exhibits substantial conformational flexibility. It transitions from closed to open conformations to expose its receptor-binding site and, subsequently, from prefusion to postfusion conformations to mediate fusion of viral and cellular membranes. S-protein derivatives are components of vaccine candidates and diagnostic assays, as well as tools for research into the biology and immunology of SARS-CoV-2. Here we have designed mutations in S that allow the production of thermostable, disulfide-bonded S-protein trimers that are trapped in the closed, prefusion state. Structures of the disulfide-stabilized and non-disulfide-stabilized proteins reveal distinct closed and locked conformations of the S trimer. We demonstrate that the designed, thermostable, closed S trimer can be used in serological assays. This protein has potential applications as a reagent for serology, virology and as an immunogen.

Combined Point-of-Care Nucleic Acid and Antibody Testing for SARS-CoV-2 following Emergence of D614G Spike Variant

Rapid COVID-19 diagnosis in the hospital is essential, although this is complicated by 30%-50% of nose/throat swabs being negative by SARS-CoV-2 nucleic acid amplification testing (NAAT). Furthermore, the D614G spike mutant dominates the pandemic and it is unclear how serological tests designed to detect anti-spike antibodies perform against this variant. We assess the diagnostic accuracy of combined rapid antibody point of care (POC) and nucleic acid assays for suspected COVID-19 disease due to either wild-type or the D614G spike mutant SARS-CoV-2. The overall detection rate for COVID-19 is 79.2% (95% CI 57.8-92.9) by rapid NAAT alone. The combined point of care antibody test and rapid NAAT is not affected by D614G and results in very high sensitivity for COVID-19 diagnosis with very high specificity.

A Comparison Between Chinese Children Infected with Coronavirus Disease-2019 and with Severe Acute Respiratory Syndrome 2003

OBJECTIVES

To compare the clinical and laboratory features of severe acute respiratory syndrome 2003 (SARS) and coronavirus disease 2019 (COVID-19) in 2 Chinese pediatric cohorts, given that the causative pathogens and are biologically similar.

STUDY DESIGN

This is a cross-sectional study reviewing pediatric patients with SARS (n = 43) and COVID-19 (n = 244) who were admitted to the Princess Margaret Hospital in Hong Kong and Wuhan Children's Hospital in Wuhan, respectively. Demographics, hospital length of stay, and clinical and laboratory features were compared.

RESULTS

Overall, 97.7% of patients with SARS and 85.2% of patients with COVID-19 had epidemiologic associations with known cases. Significantly more patients with SARS developed fever, chills, myalgia, malaise, coryza, sore throat, sputum production, nausea, headache, and dizziness than patients with COVID-19. No patients with SARS were asymptomatic at the time of admission, whereas 29.1% and 20.9% of patients with COVID-19 were asymptomatic on admission and throughout their hospital stay, respectively. More patients with SARS required oxygen supplementation than patients with COVID-19 (18.6 vs 4.7%; P = .004). Only 1.6% of patients with COVID-19 and 2.3% of patients with SARS required mechanical ventilation. Leukopenia (37.2% vs 18.6%; P = .008), lymphopenia (95.4% vs 32.6%; P < .01), and thrombocytopenia (41.9% vs 3.8%; P < .001) were significantly more common in patients with SARS than in patients with COVID-19. The duration between positive and negative nasopharyngeal aspirate and the length in hospital stay were similar in patients with COVID-19, regardless of whether they were asymptomatic or symptomatic, suggesting a similar duration of viral shedding.

CONCLUSIONS

Children with COVID-19 were less symptomatic and had more favorable hematologic findings than children with SARS.

The Roles of Neuropilin 2/VEGF-C Axis in a Series of Recurrent Lymphangioma

INTRODUCTION

 Vascular endothelial growth factor (VEGF) and its receptor act as a major contributor to lymphangioma, but their role on nonrecurrent and recurrent lymphangiomas remain unclear. We aim to investigate those factors in the generation of recurrent lymphangioma.

MATERIALS AND METHODS

 Patients diagnosed with lymphangioma from January 2005 to December 2012 in our hospital were collected and divided into nonrecurrent and recurrent lymphangiomas. The clinical characteristics including age, sex, symptoms, location, and size of lymphangioma were collected. Surgical resection samples were collected for histology, protein and mRNA detection of VEGF-C, VEGF receptor-3 (VEGFR-3), and neuropilin 2 (Nrp2). Follow-ups including lymphangioma recurrent and the local symptoms such as ulcer were reviewed.

RESULTS

 A total of 80 patients aged from 5 months to 12 years were enrolled in this study, 51 patients had no recurrence and other 29 patients suffered from recurrent lymphangioma. There was no significant difference in demographic data and clinical characters between the two groups (p > 0.05). Immunohistochemistry staining showed that VEGFR-3 remained unchanged between nonrecurrent and recurrent lymphangiomas (p > 0.05), and VEGF-C and Nrp2 were significantly increased in recurrent lymphangioma compared with nonrecurrent lymphangioma (p < 0.05). The same expression trend was proved as detected by protein and mRNA levels.

CONCLUSION

 The VEGF-C/Nrp2 axis was significantly increased in the recurrent lymphangioma, indicating that VEGF-C/Nrp2 targeted therapy may serve as a potential therapeutic strategy for recurrent lymphangioma.

Enhancing Neuraminidase Immunogenicity of Influenza A Viruses by Rewiring RNA Packaging Signals

Humoral immune protection against influenza virus infection is mediated largely by antibodies against hemagglutinin (HA) and neuraminidase (NA), the two major glycoproteins on the virus surface. While influenza virus vaccination efforts have focused mainly on HA, NA-based immunity has been shown to reduce disease severity and provide heterologous protection. Current seasonal vaccines do not elicit strong anti-NA responses-in part due to the immunodominance of the HA protein. Here, we demonstrate that by swapping the 5' and 3' terminal packaging signals of the HA and NA genomic segments, which contain the RNA promoters, we are able to rescue influenza viruses that express more NA and less HA. Vaccination with formalin-inactivated "rewired" viruses significantly enhances the anti-NA antibody response compared to vaccination with unmodified viruses. Passive transfer of sera from mice immunized with rewired virus vaccines shows better protection against influenza virus challenge. Our results provide evidence that the immunodominance of HA stems in part from its abundance on the viral surface, and that rewiring viral packaging signals-thereby increasing the NA content on viral particles-is a viable strategy for improving the immunogenicity of NA in an influenza virus vaccine.IMPORTANCE Influenza virus infections are a major source of morbidity and mortality worldwide. Increasing evidence highlights neuraminidase as a potential vaccination target. This report demonstrates the efficacy of rewiring influenza virus packaging signals for creating vaccines with more neuraminidase content which provide better neuraminidase (NA)-based protection.

Small RNA sequencing reveals miRNAs important for hypoxic adaptation in the Tibetan chicken

1. The Tibetan chicken, which is an indigenous breed living on the Tibetan Plateau, exhibits hypoxic adaptations to its high-altitude environment. However, the molecular mechanism behind this hypoxic adaptation is still unclear. This study aimed to investigate differentially expressed miRNAs involved in hypoxic adaptation through high-throughput RNA sequencing. 2. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to verify the differentially expressed miRNAs and their target genes in chicken embryonic heart tissues and fibroblasts. Luciferase reporter assays were performed to confirm the relationship between miRNAs and target genes. 3. The study identified 37 differentially expressed miRNAs in Tibetan chicken embryonic heart tissues, including 20 up- and 17 down-regulated miRNAs, compared to those found in lowland chickens. Differentially expressed miRNAs were mainly involved in biological processes, such as cell cycle arrest, toll-like receptor signalling pathways, and I-kappa B kinase/NF-kappa B signalling. The data showed that gga-miR-34 c-5p was significantly upregulated in Tibetan chicken tissues and hypoxic fibroblasts, while EHHADH, a target gene of gga-miR-34 c-5p, was downregulated. Moreover, gga-miR-34 c-5p dramatically decreased the luciferase activity of the wild EHHADH, whereas no effect on the mutational EHHADH was found. 4. This study identified miRNA expression profiles in the Tibetan chicken and suggested that miR-34 c-5p acts as a novel miRNA associated with hypoxic adaptation. This facilitates the understanding of molecular mechanisms that underlie long-term exposure to hypoxia.

Haematological and immunological data of Chinese children infected with coronavirus disease 2019

Haematological and immunological data of children with COVID-19 infection is lacking. Between 21st January and 20th March 2020, 244 children who were confirmed to have COVID-19 infection and admitted to the Wuhan Children's Hospital, China were retrospectively reviewed. 193 children were considered as symptomatic, which was defined as having either the presence of clinical symptoms or the presence of CT thorax abnormalities. Their haematological and immunological profiles, including complete blood counts, lymphocyte subsets (T, B and NK cell counts), immunoglobulin (Ig) profiles (IgG, IgA and IgM) and cytokine profiles were analysed and compared between the symptomatic and asymptomatic groups. The median values and the interquartile ranges were calculated. Comparison was made using the Mann–Whitney U test. Children with symptomatic COVID-19 infection had significantly lower haemoglobin levels, but higher absolute lymphocyte and monocyte counts, IgG and IgA levels, as well as interleukin 6 (IL-6), IL-10, tumour necrosis factor alpha and interferon gamma levels. The obtained data will be utilized for further studies in comparing children and adults with COVID-19 infections in other parts of the world and with different severity .

[Effect of pedicled thoracodorsal artery perforator flap on the repair of moderate to severe axillary scar contracture deformity]

Objective: To investigate the effect of pedicled thoracodorsal artery perforator (TDAP) flap on the repair of axillary moderate to severe scar contracture deformity. Methods: From January 2012 to January 2017, 29 patients with axillary moderate to severe scar contracture deformity were admitted to the the Second Xiangya Hospital of Central South University, including 18 females and 11 males, aged 14-42 years. There were 3 patients with cicatricial contracture deformity of bilateral axillas and 26 patients with cicatricial contracture deformity of unilateral axilla. After relevant preoperative examinations were completed and basic diseases were controlled, axillary scar was removed or released under the anesthesia of endotracheal intubation. The areas of wounds ranged from 7.5 cm×5.0 cm to 21.0 cm×8.5 cm after the operation. The pedicled TDAP flaps were used to repair the defects, which were thinned based on demand of the recipient sites before being transferred. The areas of flaps ranged from 9.0 cm×6.0 cm to 22.0 cm×10.0 cm. The donor sites were sutured directly. The status of thinned flaps, the survival of flaps after the operation and during follow-up, and the shoulder joint function during follow-up were observed. Results: Thirty-two pedicled TDAP flaps were harvested for repairing the defects. Among them, 14 flaps were transferred directly without thinning and the thickness of the flaps ranged from 9.0 mm to 15.0 mm, with average thickness of 13.6 mm.While the other 18 flaps were thinned, and the thickness of the thinned flaps ranged from 5.0 mm to 8.0 mm, with average thickness of 7.5 mm. The distal parts of 3 flaps in 3 patients showed small size of blackening or necrosis within 72 hours after the operation, and 2 of them were thinned and the other one was not. Finally, the 3 flaps were healed after hyperbaric oxygen therapy, dressing change, or other treatments. One flap occurred vein congestion 8 hours after the operation caused by pressure on the pedicle, and the color of the flap turned back to normal after the pressure was relieved. The rest of the flaps survived well. All the patients were followed up for 9 to 36 months, with an average of 18 months. All the flaps survived well, the color of the flaps was nearly the same as the recipient sites, and none of the flaps developed obvious contraction. The shoulder joint function of all patients was significantly improved compared with that before operation, with abduction angles of shoulder joints ranged from 90.0-145.0°, with an average of 130.0°. Conclusions: Pedicled TDAP flap is an relatively ideal choice for the repair of moderate to severe axillary scar contracture deformity, and better results will be achieved if the flaps are thinned to a appropriate thickness according to the condition of axillary defects.

[The value of analysis of quantitative radiomics based on DTI in predicting astrocytoma IDH1 mutation]

Objective: Non-invasive prediction of IDH1 mutations by establishing a quantitative radiographic model based on DTI-based whole-tumor texture analysis. Methods: Preoperative MRI images of patients with surgically confirmed astrocytoma were collected in the First Affiliated Hospital of Soochow University from February 2016 to June 2019, including T(1)WI, T(2)WI, DTI, and T(1)-contrast enhancement images.A total of 38 patients were included, consisting of 12 mutants and 26 wilds, 20 males and 18 females, the average age was (49±15) years old.The ROIs were drawn on each level of the T(2)WI image using MaZda software and copied to the ADC and FA maps to extract texture feature parameters. The LASSO regression was used to determine the best radiomics features, radiological scores were calculated, and binary Logistic regression was used to construct a prediction model, then the ROC curve was used to analyze the diagnostic efficiency and the calibration curve was used to evaluate model prediction performance. Results: The four most valuable radiomics features were determined by LASSO regression, and then the radiomics scores and Logistic regression models of each patient were established. The radiomics scores of the wild and mutant groups were 2.3±0.3 and 1.8±0.4. There were significant differences between the groups (P<0.05). The ROC curve analysis showed an AUC of 0.837 with sensitivity and specificity of 91.7% and 61.5%, respectively. The Logistic regression model had good predictive performance with AUC of 0.907, sensitivity and specificity of 91.7% and 84.6%. Conclusions: DTI-based whole tumor radiomics model is benefit for predicting astrocytoma IDH1 mutations.

One-step fabrication of trimetallic alloy nanozyme catalyzer for luminol-H2O2 chemiluminescence and its application for miRNA-21 detection coupled with miRNA walking machine

PtCuCo trimetallic alloys (PtCuCo-TAs) are synthesized by one-step reduction. The chemiluminescence (CL) properties of PtCuCo-TAs are studied systemically. PtCuCo-TAs show good catalyzing for luminol-H₂O₂ system. A CL platform is developed for the detection of miRNA-21 using PtCuCo-TAs as nanozyme catalyzer. In the CL detection platform, H1 (Hairpin DNA1) is immobilized onto magnetic beads (MBs) firstly. In the presence of miRNA-21, H1 is opened. H2 (Hairpin DNA2) then hybridizes with H1. Meanwhile, a "cleat" in the end of miRNA-21 with a fewer bases complementary is formed to prevent miRNA-21 dissociating from H1. This miRNA-21 hybridizes to another H1. When cpDNA-PtCuCo-TAs which consisted with cDNA (Complementary strand of probe DNA) and pDNA-PtCuCo-TAs (PtCuCo-TAs labeled with probe DNA) are added, the ssDNA region of H1 reacts with the toehold domain of probe DNA and cDNA is released resulting pDNA-PtCuCo-TAs being captured. With this process repeatedly, a lot of pDNA-PtCuCo-TAs are captured onto MBs. After separation and washing, the precipitate and H₂O₂ are put into the 96-well and luminol solution is injected. The CL signal is produced by PtCuCo-TAs catalyzing luminol-H₂O₂ system. The amount of miRNA-21 is detected with CL signal. This CL platform performs with limit of detection 0.167 fM and has good selectivity over other RNA.

Current updates on the role of reactive oxygen species in bladder cancer pathogenesis and therapeutics

Bladder cancer (BCa) is the fourth most common urological malignancy in the world, it has become the costliest cancer to manage due to its high rate of recurrence and lack of effective treatment modalities. As a natural byproduct of cellular metabolism, reactive oxygen species (ROS) have an important role in cell signaling and homeostasis. Although up-regulation of ROS is known to induce tumorigenesis, growing evidence suggests a number of agents that can selectively kill cancer cells through ROS induction. In particular, accumulation of ROS results in oxidative stress-induced apoptosis in cancer cells. So, ROS is a double-edged sword. A modest level of ROS is required for cancer cells to survive, whereas excessive levels kill them. This review summarizes the up-to-date findings of oxidative stress-regulated signaling pathways and transcription factors involved in the etiology and progression of BCa and explores the possible therapeutic implications of ROS regulators as therapeutic agents for BCa.

Five Constituents in Psoralea corylifolia L. Attenuate Palmitic Acid-Induced Hepatocyte Injury via Inhibiting the Protein Kinase C-α/Nicotinamide-Adenine Dinucleotide Phosphate Oxidase Pathway

Psoralea corylifolia L. (PC) is a traditional Chinese herb used to treat yang deficiency of the spleen and kidney in pediatric disease. Our previous studies have found that PC can alleviate the liver oxidative stress of juvenile mice with nonalcoholic steatohepatitis (NASH), and its mechanism is related to the inhibition of the protein kinase C-α (PKC-α)/nicotinamide-adenine dinucleotide phosphate oxidase (NOX) signaling pathway. The aim of this study was to confirm the aforementioned drug target in vitro and to conduct preliminary screening for some effective compounds of PC on the treatment of NASH. A primary hepatocyte model of non alcoholic fatty liver disease was established by palmitic acid. The existence of Psoralen, Isopsoralen, Neobavaisoflavone, Isobavachalcone, and Bakuchiol were identified by ultra-performance liquid chromatography. Then, five PC compounds were administered. Intracellular triglyceride and total cholesterol content, the cell supernatant alanine aminotransferase and aspartate aminotransferase, and hepatocellular superoxide anion were examined. The changes of PKC-α/NOX signaling pathways in hepatocytes were also determined. Furthermore, PKC-α activator phorbol 12-myristate 13-acetate was administered for 4 h before Psoralen intervention was conducted again to detect the changes of PKC-α/NOX signaling pathways. Our data demonstrated that Psoralen, Isopsoralen, and Isobavachalcone decreased intracellular content of triglyceride while all five PC compounds improved hepatocellular total cholesterol accumulation and hepatocyte damage in palmitic acid-induced primary hepatocyte model of non alcoholic fatty liver disease. All five PC compounds could also reduce hepatocytic superoxide anion levels, nicotinamide-adenine dinucleotide phosphate/reduced nicotinamide-adenine dinucleotide phosphate ratio, NOX activity as well as p47^phox protein expression and PKCα activation in hepatocytes. Psoralen exhibited the best efficacy but the effectiveness was lost when pre-stimulated by phorbol 12-myristate 13-acetate. The results suggest that Psoralen, Isopsoralen, and Isobavachalcone could improve hepatocyte steatosis; five PC compounds could ameliorate hepatocyte injury, relieve oxidative stress, and downregulate the PKC-α/NOX signaling pathway of hepatocytes. In addition, Psoralen exhibits the best efficacy and a prospective PKC-α inhibitor pharmaceutical activity.

Photoelectric current as a highly sensitive readout for potentiometric sensors

The photocurrent at a working electrode coated with a ZnSe/r-GO composite can be modulated by a polymeric membrane ion-selective electrode that works as a reference electrode.

MicroRNAs in the Intestine: Role in Renewal, Homeostasis, and Inflammation

The mammalian intestine is not only an organ for food digestion and nutrient absorption but also an integral part of the immune and endocrine systems. The intestinal epithelium under stressful environments requires epithelial cells to rapidly elicit changes in gene expression patterns to regulate their survival, adapt to stress, and maintain epithelial homeostasis. Recently, miRNAs have emerged as a novel class of posttranscriptional gene regulators that are fundamentally involved in many aspects of intestinal epithelial differentiation, architecture, and barrier function. In this review, we highlight the critical roles of miRNAs in both the crypt-villus axis of cellular self-renewal and inflammation in the mammalian intestinal mucosa and their impact on the microbiota. We also discuss the functions of specific miRNAs within the intestine to better understand the cellular mechanisms that promote intestinal homeostasis, and the influence of dietary components in the regulation of endogenous miRNA in the study of nutrition and gene regulation in intestinal health.

Boron Phosphide Nanoparticles: A Nonmetal Catalyst for High-Selectivity Electrochemical Reduction of CO2 to CH3 OH

Electrocatalysis has emerged as an attractive way for artificial CO₂ fixation to CH₃ OH, but the design and development of metal-free electrocatalyst for highly selective CH₃ OH formation still remains a key challenge. Here, it is demonstrated that boron phosphide nanoparticles perform highly efficiently as a nonmetal electrocatalyst toward electrochemical reduction of CO₂ to CH₃ OH with high selectivity. In 0.1 m KHCO₃ , this catalyst achieves a high Faradaic efficiency of 92.0% for CH₃ OH at -0.5 V versus reversible hydrogen electrode. Density functional theory calculations reveal that B and P synergistically promote the binding and activation of CO₂ , and the rate-determining step for the CO₂ reduction reaction is dominated by *CO + *OH to *CO + *H₂ O process with free energy change of 1.36 eV. In addition, CO and CH₂ O products are difficultly generated on BP (111) surface, which is responsible for the high activity and selectivity of the CO₂ -to-CH₃ OH conversion process.