Bayesian-frequentist hybrid inference framework for single cell RNA-seq analyses.

BACKGROUND: Single cell RNA sequencing technology (scRNA-seq) has been proven useful in understanding cell-specific disease mechanisms. However, identifying genes of interest remains a key challenge. Pseudo-bulk methods that pool scRNA-seq counts in the same biological replicates have been commonly used to identify differentially expressed genes. However, such methods may lack power due to the limited sample size of scRNA-seq datasets, which can be prohibitively expensive. RESULTS: Motivated by this, we proposed to use the Bayesian-frequentist hybrid (BFH) framework to increase the power and we showed in simulated scenario, the proposed BFH would be an optimal method when compared with other popular single cell differential expression methods if both FDR and power were considered. As an example, the method was applied to an idiopathic pulmonary fibrosis (IPF) case study. CONCLUSION: In our IPF example, we demonstrated that with a proper informative prior, the BFH approach identified more genes of interest. Furthermore, these genes were reasonable based on the current knowledge of IPF. Thus, the BFH offers a unique and flexible framework for future scRNA-seq analyses.

Associations between brain imaging-derived phenotypes and cognitive functions.

We aimed to evaluate the potential causal relationship between brain imaging-derived phenotypes and cognitive functions via Mendelian randomization analyses. Genetic instruments for 470 brain imaging-derived phenotypes were selected from a genome-wide association study based on the UK Biobank (n = 33,224). Statistics for cognitive functions were obtained from the genome-wide association study based on the UK Biobank. We used the inverse variance weighted Mendelian randomization method to investigate the associations between brain imaging-derived phenotypes and cognitive functions, and reverse Mendelian randomization analyses were performed for significant brain imaging-derived phenotypes to examine the reverse causation for the identified associations. We identified three brain imaging-derived phenotypes to be associated with verbal-numerical reasoning, including cortical surface area of the left fusiform gyrus (beta, 0.18 [95% confidence interval, 0.11 to 0.25], P = 4.74 × 10-7), cortical surface area of the right superior temporal gyrus (beta, 0.25 [95% confidence interval, 0.15 to 0.35], P = 6.30 × 10-7), and orientation dispersion in the left superior longitudinal fasciculus (beta, 0.14 [95% confidence interval, 0.09 to 0.20], P = 8.37 × 10-7). The reverse Mendelian randomization analysis indicated that verbal-numerical reasoning had no effect on these three brain imaging-derived phenotypes. This Mendelian randomization study identified cortical surface area of the left fusiform gyrus, cortical surface area of the right superior temporal gyrus, and orientation dispersion in the left superior longitudinal fasciculus as predictors of verbal-numerical reasoning.

Genetic analyses identify brain imaging-derived phenotypes associated with the risk of amyotrophic lateral sclerosis.

Brain imaging-derived phenotypes have been suggested to be associated with amyotrophic lateral sclerosis in observational studies, but whether these associations are causal remains unclear. We aimed to assess the potential bidirectional causal associations between imaging-derived phenotypes and amyotrophic lateral sclerosis using bidirectional 2-sample Mendelian randomization analyses. Summary statistics for 469 imaging-derived phenotypes (33,224 individuals) and amyotrophic lateral sclerosis (20,806 cases and 59,804 controls) were obtained from 2 large-scale genome-wide association studies of European ancestry. We used the inverse-variance weighted Mendelian randomization method in the main analysis to assess the bidirectional associations between imaging-derived phenotypes and amyotrophic lateral sclerosis, followed by several sensitivity analyses for robustness validation. In the forward Mendelian randomization analyses, we found that genetically determined high orientation dispersion index in the right cerebral peduncle was associated with the increased risk of amyotrophic lateral sclerosis (odds ratio = 1.30, 95% confidence interval = 1.16-1.45, P = 2.26 × 10-6). In addition, the reverse Mendelian randomization analysis indicated that amyotrophic lateral sclerosis had no effect on 469 imaging-derived phenotypes. Mendelian randomization-Egger regression analysis showed no directional pleiotropy for the association between high orientation dispersion index in the right cerebral peduncle and amyotrophic lateral sclerosis, and sensitivity analyses with different Mendelian randomization models further confirmed these findings. The present systematic bidirectional Mendelian randomization analysis showed that high orientation dispersion index in the right cerebral peduncle might be the potential causal mediator of amyotrophic lateral sclerosis, which may provide predictive guidance for the prevention of amyotrophic lateral sclerosis. Further studies are warranted to replicate our findings and clarify the underlying mechanisms.

Genetic analyses identify brain imaging-derived phenotypes associated with the risk of intracerebral hemorrhage.

Previous observational studies have reported associations between brain imaging-derived phenotypes (IDPs) and intracerebral hemorrhage (ICH), but the causality between them remains uncertain. We aimed to investigate the potential causal relationship between IDPs and ICH by a two-sample Mendelian randomization (MR) study. We selected genetic instruments for 363 IDPs from a genome-wide association study (GWASs) based on the UK Biobank (n = 33,224). Summary-level data on ICH was derived from a European-descent GWAS with 1,545 cases and 1,481 controls. Inverse variance weighted MR method was applied in the main analysis to investigate the associations between IDPs and ICH. Reverse MR analyses were performed for significant IDPs to examine the reverse causation for the identified associations. Among the 363 IDPs, isotropic or free water volume fraction (ISOVF) in the anterior limb of the left internal capsule was identified to be associated with the risk of ICH (OR per 1-SD increase, 4.62 [95% CI, 2.18-9.81], P = 6.63 × 10-5). In addition, the reverse MR analysis indicated that ICH had no effect on ISOVF in the anterior limb of the left internal capsule (beta, 0.010 [95% CI, -0.010-0.030], P = 0.33). MR-Egger regression analysis showed no directional pleiotropy for the association between ISOVF and ICH, and sensitivity analyses with different MR models further confirmed these findings. ISOVF in the anterior limb of the left internal capsule might be a potential causal mediator of ICH, which may provide predictive guidance for the prevention of ICH. Further studies are warranted to replicate our findings and clarify the underlying mechanisms.

Interfacial Stereoelectronic Effect Induced by Anchoring Orientation.

Heterogeneous interfaces in most devices play a key role in the material performance. Exploring the atomic structure and electronic properties of metal-molecule interfaces is critical for various potential applications, such as surface sensing, molecular recognition, and molecular electronic devices. This study unveils a ubiquitous interfacial stereoelectronic effect in conjugated molecular junctions by combining first-principles simulation and scanning tunneling microscopy break junction technology. Single-molecule junctions with same-side interfacial anchoring (cis configuration) exhibit higher conductance than those with opposite-side interfacial anchoring (trans configuration). The cis and trans configurations can undergo reversible conversions, resulting in a conductance switching. The stability of these configurations can be adjusted by an electric field, achieving precise regulation of conductance states. Our findings provide important insights for designing high-quality materials and enhancing the device performance.

Genetically Determined Plasma Hepatocyte Growth Factor Levels Are Associated With the Risk and Prognosis of Ischemic Stroke.

BACKGROUND: Observational studies suggest that hepatocyte growth factor (HGF) is associated with the risk and prognosis of ischemic stroke, but the causality of these associations remains unclear. Therefore, we conducted Mendelian randomization (MR) analyses to explore the associations of genetically determined plasma HGF levels with the risk and prognosis of ischemic stroke. METHODS: A total of 13 single-nucleotide polymorphisms associated with plasma HGF were selected as genetic instruments based on the data from a genome-wide association study with 21 758 European participants. Summary data about the risk of ischemic stroke were obtained from the MEGASTROKE (Multiancestry Genome-Wide Association Study of Stroke) Consortium with 34 217 ischemic stroke cases and 406 111 controls of European ancestry, and summary data about the prognosis of ischemic stroke were obtained from the GISCOME study (Genetics of Ischaemic Stroke Functional Outcome) with 6165 European patients with ischemic stroke. We conducted an inverse-variance weighted Mendelian randomization analysis followed by a series of sensitivity analyses to evaluate the associations of genetically determined plasma HGF with the risk and prognosis of ischemic stroke. RESULTS: The primary analyses showed that genetically determined high HGF was associated with an increased risk of ischemic stroke (odds ratio per SD increase, 1.11 [95% CI, 1.04-1.19]; P=1.10×10-3) and poor prognosis of ischemic stroke (odds ratio per SD increase, 2.43 [95% CI, 1.76-3.52]; P=6.35×10-8). In the secondary analysis, genetically determined plasma HGF was associated with a high risk of large atherosclerotic stroke (odds ratio per SD increase, 1.39 [95% CI, 1.18-1.63]; P=5.08×10-5) but not small vessel stroke and cardioembolic stroke. Mendelian randomization-Egger regression showed no directional pleiotropy for all associations, and the sensitivity analyses with different Mendelian randomization methods further confirmed these findings. CONCLUSIONS: We found positive associations of genetically determined plasma HGF with the risk and prognosis of ischemic stroke, suggesting that HGF might be implicated in the occurrence and development of ischemic stroke.

High-Serum Brain-Derived Neurotrophic Factor Levels Are Associated With Decreased Risk of Poststroke Cognitive Impairment.

BACKGROUND: BDNF (brain-derived neurotrophic factor) is widely implicated in the pathophysiological process of stroke, but the effect of BDNF on poststroke cognitive impairment (PSCI) remains unclear. We aimed to investigate the association between baseline serum BDNF and the risk of PSCI at 3 months in a multicenter study based on a preplanned ancillary study of the CATIS trial (China Antihypertensive Trial in Acute Ischemic Stroke). METHODS: We examined serum BDNF levels at baseline and used the Mini-Mental State Examination and Montreal Cognitive Assessment to evaluate cognitive function at 3-month follow-up after ischemic stroke. PSCI was defined as Mini-Mental State Examination score <27 or Montreal Cognitive Assessment score <25. Logistic regression analyses were performed to evaluate the association between serum BDNF and the risk of 3-month PSCI. RESULTS: In this ancillary study, a total of 660 patients with ischemic stroke with hypertension were included, and 593 patients (mean age, 59.90±10.44 years; 410 males and 183 females) were finally included in this analysis. According to mini-mental state examination score, after adjustment for age, sex, education, baseline National Institutes of Health Stroke Scale score, APOE ɛ4 carriers, and other potential confounders, the odds ratio of PSCI for the highest tertile of BDNF was 0.60 ([95% CI, 0.39-0.94]; P=0.024) compared with the lowest tertile. Multiple-adjusted spline regression model showed a linear association of serum BDNF levels with PSCI at 3 months (P value for linearity=0.010). Adding serum BDNF to conventional prognostic factors slightly improved the risk reclassification of PSCI (net reclassification improvement: 27.46%, P=0.001; integrated discrimination index: 1.02%, P=0.015). Similar significant findings were observed when PSCI was defined by the Montreal Cognitive Assessment score. CONCLUSIONS: Elevated serum BDNF levels were associated with a decreased risk of PSCI at 3 months, suggesting that serum BDNF might be a potential predictive biomarker for PSCI among patients with ischemic stroke with hypertension.

In Situ Detection of Interfacial Ions at the Single-Bond Level.

Detecting the ionic state at the solid-liquid interface is essential to reveal the various chemical and physical processes that occur at the interface. In this study, the adsorption states of the highly electronegative ions F- and OH- at the solid-liquid interface are detected by using the scanning tunneling microscopy break junction technique. With the active hydrogen atom of the amino group as a probe, the formed ionic hydrogen bonds are successfully detected, thereby enabling in situ monitoring of the ionic state at the solid-liquid interface. Through noise power spectral density analysis and theoretical simulations, we reveal the mechanism by which ionic hydrogen bonds at the interface affect the charge transport properties. In addition, we discover that the ionic state at the solid-liquid interface can be effectively manipulated by electric fields. Under high electric fields, the concentration of the anion near the electrode is higher, and the proportion of hydrogen bonds formed is greater than that under low electric fields. This study of the interfacial ionic state at the single-bond level provides guidance for the design of high-performance materials for energy conversion and environmental purification.

CuO Nanozymes Catalyze Cysteine and Glutathione Depletion Induced Ferroptosis and Cuproptosis for Synergistic Tumor Therapy.

The latest research identifies that cysteine (Cys) is one of the key factors in tumor proliferation, metastasis, and recurrence. The direct depletion of intracellular Cys shows a profound antitumor effect. However, using nanozymes to efficiently deplete Cys for tumor therapy has not yet attracted widespread attention. Here, a (3-carboxypropyl) triphenylphosphonium bromide-derived hyaluronic acid-modified copper oxide nanorods (denoted as MitCuOHA) are designed with cysteine oxidase-like, glutathione oxidase-like and peroxidase-like activities to realize Cys depletion and further induce cellular ferroptosis and cuproptosis for synergistic tumor therapy. MitCuOHA nanozymes can efficiently catalyze the depletion of Cys and glutathione (GSH), accompanied by the generation of H2O2 and the subsequent conversion into highly active hydroxyl radicals, thereby successfully inducing ferroptosis in cancer cells. Meanwhile, copper ions released by MitCuOHA under tumor microenvironment stimulation directly bind to lipoylated proteins of the tricarboxylic acid cycle, leading to the abnormal aggregation of lipoylated proteins and subsequent loss of iron-sulfur cluster proteins, which ultimately triggers proteotoxic stress and cell cuproptosis. Both in vitro and in vivo results show the drastically enhanced anticancer efficacy of Cys oxidation catalyzed by the MitCuOHA nanozymes, demonstrating the high feasibility of such catalytic Cys depletion-induced synergistic ferroptosis and cuproptosis therapeutic concept.

Association of Crohn's disease and ulcerative colitis with the risk of neurological diseases: a large-scale Mendelian randomization study.

Observational studies suggested increased risks of Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS) in patients with Crohn's disease (CD) and ulcerative colitis (UC). We aimed to assess the causality for the associations of CD and UC with the risks of AD, PD, and MS through a two-sample Mendelian randomization (MR) study. Independent single nucleotide polymorphisms associated with CD (17,897 cases and 33,977 controls) and UC (13,768 cases and 33,977 controls) were identified as genetic instruments based on a European-descent genome-wide association study (GWAS) released by the International Inflammatory Bowel Disease Genetics Consortium. Summary statistics for AD (combined: 25,881 cases and 256,837 controls), PD (combined: 35,836 cases and 665,686 controls), and MS (combined: 48,477 cases and 285,515 controls) were obtained from the largest GWASs and FinnGen study of European ancestry, respectively. MR estimates were generated using the inverse-variance weighted method in the main analysis with a series of sensitivity analyses. MR analyses were conducted per outcome database and were subsequently meta-analyzed to generate combined estimates. Genetically predicted UC was significantly associated with increased risks of AD (combined: OR, 1.03; 95% CI, 1.01-1.05; P = 1.80 × 10-3) and MS (combined: OR, 1.37; 95% CI, 1.23-1.53; P = 1.18 × 10-8), while there was no association between genetically predicted UC and the risk of PD. In contrast, no significant associations were observed for genetically predicted CD with AD, PD, and MS. MR-Egger regression showed no directional pleiotropy for the identified associations, and sensitivity analyses with different MR methods further confirmed these findings. This study suggested significant adverse effects of UC on AD and MS, highlighting that UC patients should receive early intervention with optimal adjunctive medical therapy to reduce the risks of AD and MS.

Smad2/3/4 complex could undergo liquid liquid phase separation and induce apoptosis through TAT in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) represents one of the most significant causes of mortality due to cancer-related deaths. It has been previously reported that the TGF-ß signaling pathway may be associated with tumor progression. However, the relationship between TGF-ß signaling pathway and HCC remains to be further elucidated. The objective of our research was to investigate the impact of TGF-ß signaling pathway on HCC progression as well as the potential regulatory mechanism involved. METHODS: We conducted a series of bioinformatics analyses to screen and filter the most relevant hub genes associated with HCC. E. coli was utilized to express recombinant protein, and the Ni-NTA column was employed for purification of the target protein. Liquid liquid phase separation (LLPS) of protein in vitro, and fluorescent recovery after photobleaching (FRAP) were utilized to verify whether the target proteins had the ability to drive force LLPS. Western blot and quantitative real-time polymerase chain reaction (qPCR) were utilized to assess gene expression levels. Transcription factor binding sites of DNA were identified by chromatin immunoprecipitation (CHIP) qPCR. Flow cytometry was employed to examine cell apoptosis. Knockdown of target genes was achieved through shRNA. Cell Counting Kit-8 (CCK-8), colony formation assays, and nude mice tumor transplantation were utilized to test cell proliferation ability in vitro and in vivo. RESULTS: We found that Smad2/3/4 complex could regulate tyrosine aminotransferase (TAT) expression, and this regulation could relate to LLPS. CHIP qPCR results showed that the key targeted DNA binding site of Smad2/3/4 complex in TAT promoter region is -1032 to -1182. In addition. CCK-8, colony formation, and nude mice tumor transplantation assays showed that Smad2/3/4 complex could repress cell proliferation through TAT. Flow cytometry assay results showed that Smad2/3/4 complex could increase the apoptosis of hepatoma cells. Western blot results showed that Smad2/3/4 complex would active caspase-9 through TAT, which uncovered the mechanism of Smad2/3/4 complex inducing hepatoma cell apoptosis. CONCLUSION: This study proved that Smad2/3/4 complex could undergo LLPS to active TAT transcription, then active caspase-9 to induce hepatoma cell apoptosis in inhibiting HCC progress. The research further elucidate the relationship between TGF-ß signaling pathway and HCC, which contributes to discover the mechanism of HCC development.

Mendelian randomization analysis implicates bidirectional associations between brain imaging-derived phenotypes and ischemic stroke.

Brian imaging-derived phenotypes (IDPs) have been suggested to be associated with ischemic stroke, but the causality between them remains unclear. In this bidirectional two-sample Mendelian randomization (MR) study, we explored the potential causal relationship between 461 imaging-derived phenotypes (n = 33,224, UK Biobank) and ischemic stroke (n = 34,217 cases/406,111 controls, Multiancestry Genome-Wide Association Study of Stroke). Forward MR analyses identified five IDPs associated with ischemic stroke, including mean diffusivity (MD) in the right superior fronto-occipital fasciculus (1.22 [95% CI, 1.11-1.34]), MD in the left superior fronto-occipital fasciculus (1.30 [1.17-1.44]), MD in the anterior limb of the right internal capsule (1.36 [1.22-1.51]), MD in the right anterior thalamic radiation (1.17 [1.09-1.26]), and MD in the right superior thalamic radiation (1.23 [1.11-1.35]). In the reverse MR analyses, ischemic stroke was identified to be associated with three IDPs, including high isotropic or free water volume fraction in the body of corpus callosum (beta, 0.189 [95% confidence interval, 0.107-0.271]), orientation dispersion index in the pontine crossing tract (0.175 [0.093-0.257]), and volume of the third ventricle (0.219 [0.138-0.301]). This bidirectional two-sample MR study suggested five predictors and three diagnostic markers for ischemic stroke at the brain-imaging level. Further studies are warranted to replicate our findings and clarify underlying mechanisms.

The bidirectional association between frailty index and cardiovascular disease: A Mendelian randomization study.

BACKGROUND AND AIM: Observational studies have suggested a relationship between frailty and cardiovascular disease (CVD), but the causality is still uncertain. We used bidirectional Mendelian randomization (MR) design to investigate the potential causal associations between frailty and four main CVDs, including hypertension, myocardial infarction (MI), heart failure (HF), and atrial fibrillation (AF). METHODS AND RESULTS: Independent single-nucleotide polymorphisms for frailty index (FI) and CVDs (hypertension, MI, HF, and AF) were selected as genetic instruments based on European-descent genome-wide association studies (GWASs). Summary-level data for outcomes on FI (n = 175,226), hypertension (n = 463,010), MI (n = 171,875), HF (n = 977323), and AF (n = 1,030,836) was derived from five large-scale GWASs of European ancestry. We used the inverse-variance weighted (IVW) method to examine the bidirectional associations between FI and CVDs in the main analyses. In the IVW MR analyses, genetically determined high FI was significantly associated with increased risks of hypertension (odds ratio [OR] per 1-SD increase: 1.07 [95 % confidence interval, 1.05-1.08]), MI (OR per 1-SD increase: 1.74 [1.21-2.51]), HF (OR per 1-SD increase: 1.28 [1.10-1.48]), and AF (OR per 1-SD increase: 1.20 [1.08-1.33]). In addition, genetically determined hypertension (beta: 1.406 [1.225-1.587]), MI (beta: 0.045 [0.023-0.067]), HF (beta: 0.105 [0.066-0.143]) and AF (beta: 0.021 [0.012-0.031]) were significantly associated with high FI. These findings were robustly supported by a series of sensitivity analyses with different MR models. CONCLUSIONS: We found potential bidirectional causal associations between elevated FI and increased risks of CVD, suggesting mutual risk factors between frailty and CVD.

Optimization of AgIO3/Bi4Ti3O12 composite photocatalyst to achieve enhanced photocatalytic performance by adjusting internal electric field via oxygen defect engineering.

The construction of heterojunction is an effective and conventional method to improve the photocatalytic activity of photocatalysts. On this basis, how to further regulate the separation and migration of photogenerated carrier is worthy of further investigation. As a mature and efficient modification method, oxygen defect engineering was used to regulate the S-scheme heterojunction composed of AgIO3 and Bi4Ti3O12 to further enhance the photocatalytic activity of the constructed heterojunction in this study. In addition to improving the visible light absorption of the photocatalyst and providing active sites, the introduction of oxygen vacancies can also strengthen the internal electric field between the two semiconductors by expanding the Fermi level gap, which can be verified by Mott-Schottky experiment and DFT calculations, resulting in more efficient photogenerated carrier separation efficiency. As a result, compared with AgIO3/Bi4Ti3O12, the AgIO3/Bi4Ti3O12 heterojunction modulated by oxygen defect engineering exhibited excellent photocatalytic activity, which proves the feasibility of the regulation of the interfacial electric field. This work provides a new idea for the modulation strategy of the interface electric field.

Asynchronous and error-prone longitudinal data analysis via functional calibration.

In many longitudinal settings, time-varying covariates may not be measured at the same time as responses and are often prone to measurement error. Naive last-observation-carried-forward methods incur estimation biases, and existing kernel-based methods suffer from slow convergence rates and large variations. To address these challenges, we propose a new functional calibration approach to efficiently learn longitudinal covariate processes based on sparse functional data with measurement error. Our approach, stemming from functional principal component analysis, calibrates the unobserved synchronized covariate values from the observed asynchronous and error-prone covariate values, and is broadly applicable to asynchronous longitudinal regression with time-invariant or time-varying coefficients. For regression with time-invariant coefficients, our estimator is asymptotically unbiased, root-n consistent, and asymptotically normal; for time-varying coefficient models, our estimator has the optimal varying coefficient model convergence rate with inflated asymptotic variance from the calibration. In both cases, our estimators present asymptotic properties superior to the existing methods. The feasibility and usability of the proposed methods are verified by simulations and an application to the Study of Women's Health Across the Nation, a large-scale multisite longitudinal study on women's health during midlife.

scRAA: the development of a robust and automatic annotation procedure for single-cell RNA sequencing data.

A critical task in single-cell RNA sequencing (scRNA-Seq) data analysis is to identify cell types from heterogeneous tissues. While the majority of classification methods demonstrated high performance in scRNA-Seq annotation problems, a robust and accurate solution is desired to generate reliable outcomes for downstream analyses, for instance, marker genes identification, differentially expressed genes, and pathway analysis. It is hard to establish a universally good metric. Thus, a universally good classification method for all kinds of scenarios does not exist. In addition, reference and query data in cell classification are usually from different experimental batches, and failure to consider batch effects may result in misleading conclusions. To overcome this bottleneck, we propose a robust ensemble approach to classify cells and utilize a batch correction method between reference and query data. We simulated four scenarios that comprise simple to complex batch effect and account for varying cell-type proportions. We further tested our approach on both lung and pancreas data. We found improved prediction accuracy and robust performance across simulation scenarios and real data. The incorporation of batch effect correction between reference and query, and the ensemble approach improve cell-type prediction accuracy while maintaining robustness. We demonstrated these through simulated and real scRNA-Seq data.

Quantum Interference-Controlled Conductance Enhancement in Stacked Graphene-like Dimers.

Stacking interactions are of significant importance in the fields of chemistry, biology, and material optoelectronics because they determine the efficiency of charge transfer between molecules and their quantum states. Previous studies have proven that when two monomers are π-stacked in series to form a dimer, the electrical conductance of the dimer is significantly lower than that of the monomer. Here, we present a strong opposite case that when two anthanthrene monomers are π-stacked to form a dimer in a scanning tunneling microscopic break junction, the conductance increases by as much as 25 in comparison with a monomer, which originates from a room-temperature quantum interference. Remarkably, both theory and experiment consistently reveal that this effect can be reversed by changing the connectivity of external electrodes to the monomer core. These results demonstrate that synthetic control of connectivity to molecular cores can be combined with stacking interactions between their π systems to modify and optimize charge transfer between molecules, opening up a wide variety of potential applications ranging from organic optoelectronics and photovoltaics to nanoelectronics and single-molecule electronics.

Molecular definition of severe acute respiratory syndrome coronavirus 2 receptor-binding domain mutations: Receptor affinity versus neutralization of receptor interaction.

BACKGROUND: Several new variants of SARS-CoV-2 have emerged since fall 2020 which have multiple mutations in the receptor-binding domain (RBD) of the spike protein. It is unclear which mutations affect receptor affinity versus immune recognition. METHODS: We produced wild type RBD, RBD with single mutations (E484K, K417N, or N501Y) or with all three mutations combined and tested their binding to ACE2 by biolayer interferometry (BLI). The ability of convalescent sera to recognize RBDs and block their interaction with ACE2 was tested as well. RESULTS: We demonstrated that single mutation N501Y increased binding affinity to ACE2 but did not strongly affect its recognition by convalescent sera. In contrast, single mutation E484K had almost no impact on the binding kinetics, but essentially abolished recognition of RBD by convalescent sera. Interestingly, combining mutations E484K, K417N, and N501Y resulted in a RBD with both features: enhanced receptor binding and abolished immune recognition. CONCLUSIONS: Our data demonstrate that single mutations either affect receptor affinity or immune recognition while triple mutant RBDs combine both features.

Intranasal administration of a virus like particles-based vaccine induces neutralizing antibodies against SARS-CoV-2 and variants of concern.

BACKGROUND: The highly contagious SARS-CoV-2 is mainly transmitted by respiratory droplets and aerosols. Consequently, people are required to wear masks and maintain a social distance to avoid spreading of the virus. Despite the success of the commercially available vaccines, the virus is still uncontained globally. Given the tropism of SARS-CoV-2, a mucosal immune reaction would help to reduce viral shedding and transmission locally. Only seven out of hundreds of ongoing clinical trials are testing the intranasal delivery of a vaccine against COVID-19. METHODS: In the current study, we evaluated the immunogenicity of a traditional vaccine platform based on virus-like particles (VLPs) displaying RBD of SARS-CoV-2 for intranasal administration in a murine model. The candidate vaccine platform, CuMVTT -RBD, has been optimized to incorporate a universal T helper cell epitope derived from tetanus-toxin and is self-adjuvanted with TLR7/8 ligands. RESULTS: CuMVTT -RBD vaccine elicited a strong systemic RBD- and spike-IgG and IgA antibodies of high avidity. Local immune response was assessed, and our results demonstrate a strong mucosal antibody and plasma cell production in lung tissue. Furthermore, the induced systemic antibodies could efficiently recognize and neutralize different variants of concern (VOCs). CONCLUSION: Our data demonstrate that intranasal administration of CuMVTT -RBD induces a protective systemic and local specific antibody response against SARS-CoV-2 and its VOCs.

A scalable and highly immunogenic virus-like particle-based vaccine against SARS-CoV-2.

BACKGROUND: SARS-CoV-2 caused one of the most devastating pandemics in the recent history of mankind. Due to various countermeasures, including lock-downs, wearing masks, and increased hygiene, the virus has been controlled in some parts of the world. More recently, the availability of vaccines, based on RNA or adenoviruses, has greatly added to our ability to keep the virus at bay; again, however, in some parts of the world only. While available vaccines are effective, it would be desirable to also have more classical vaccines at hand for the future. Key feature of vaccines for long-term control of SARS-CoV-2 would be inexpensive production at large scale, ability to make multiple booster injections, and long-term stability at 4℃. METHODS: Here, we describe such a vaccine candidate, consisting of the SARS-CoV-2 receptor-binding motif (RBM) grafted genetically onto the surface of the immunologically optimized cucumber mosaic virus, called CuMVTT -RBM. RESULTS: Using bacterial fermentation and continuous flow centrifugation for purification, the yield of the production process is estimated to be >2.5 million doses per 1000-litre fermenter run. We demonstrate that the candidate vaccine is highly immunogenic in mice and rabbits and induces more high avidity antibodies compared to convalescent human sera. The induced antibodies are more cross-reactive to mutant RBDs of variants of concern (VoC). Furthermore, antibody responses are neutralizing and long-lived. In addition, the vaccine candidate was stable for at least 14 months at 4℃. CONCLUSION: Thus, the here presented VLP-based vaccine may be a good candidate for use as conventional vaccine in the long term.