Induction of Broadly Cross-Reactive Antibodies by Displaying Receptor Binding Domains of SARS-CoV-2 on Virus-like Particles.

The impact of the COVID-19 pandemic has been reduced since the application of vaccination programs, mostly shown in the reduction of hospitalized patients. However, the emerging variants, in particular Omicron, have caused a steep increase in the number of infections; this increase is, nevertheless, not matched by an increase in hospitalization. Therefore, a vaccine that induces cross-reactive antibodies against most or all variants is a potential solution for the issue of emerging new variants. Here, we present a vaccine candidate which displays receptor-binding domain (RBD) of SARS-CoV-2 on virus-like particles (VLP) that, in mice, not only induce strong antibody responses against RBD but also bind RBDs from other variants of concern (VOCs). The antibodies induced by wild-type (wt) RBD displayed on immunologically optimized Cucumber mosaic virus incorporated tetanus toxin (CuMVTT) VLPs bind to wt as well as RBDs of VOCs with high avidities, indicating induction of strongly cross-reactive IgG antibodies. Interestingly, similar cross-reactive IgA antibodies were induced in immunized mice. Furthermore, these cross-reactive antibodies demonstrated efficacy in neutralizing wt (Wuhan) as well as SARS-CoV-2 VOCs (Beta, Delta, and Gamma). In summary, RBDs displayed on VLPs are capable of inducing protective cross-reactive IgG and IgA antibodies in mice, indicating that it may be possible to cover emerging VOCs with a single vaccine based on wt RBD

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

Homoisoflavonoids are potent glucose transporter 2 (GLUT 2) inhibitors–a potential mechanism for the glucose-lowering properties of Polygonatum odoratum

Foods of high carbohydrate content such as sucrose or starch increase postprandial blood glucose concentrations. The glucose absorption system in the intestine comprises two components: sodium-dependent glucose transporter-1 (SGLT1) and glucose transporter 2 (GLUT2). Here five sappanin-type (SAP) homoisoflavonoids were identified as novel potent GLUT2 inhibitors, with three of them isolated from the fibrous roots of Polygonatum odoratum (Mill.) Druce. SAP homoisolflavonoids had a stronger inhibitory effect on 25 mM glucose transport (41.6 ± 2.5, 50.5 ± 7.6, 47.5 ± 1.9, 42.6 ± 2.4, and 45.7 ± 4.1% for EA-1, EA-2, EA-3, MOA, and MOB) than flavonoids (19.3 ± 2.2, 11.5 ± 3.7, 16.4 ± 2.4, 5.3 ± 1.0, 3.7 ± 2.2, and 18.1 ± 2.4% for apigenin, luteolin, quercetin, naringenin, hesperetin, and genistein) and phloretin (28.1 ± 1.6%) at 15 μM. SAP homoisoflavonoids and SGLT1 inhibitors were found to synergistically inhibit the uptake of glucose using an in vitro model comprising Caco-2 cells. This observed new mechanism of the glucose-lowering action of P. odoratum suggests that SAP homoisoflavonoids and their combination with flavonoid monoglucosides show promise as naturally functional ingredients for inclusion in foods and drinks designed to control postprandial glucose levels

Characterization of two immunomodulating homogalacturonan pectins from green tea

Two natural homogalacturonan (HG) pectins (MW ca. 20 kDa) were isolated from green tea based on their immunomodulatory activity. The crude tea polysaccharides (TPS1 and TPS2) were obtained from green tea leaves by hot water extraction and followed by 40% and 70% ethanol precipitation, respectively. Two homogenous water soluble polysaccharides (TPS1-2a and TPS1-2b) were obtained from TPS1 after purification with gel permeation, which gave a higher phagocytic effect than TPS2. A combination of composition, methylation and configuration analyses, as well as NMR (nuclear magnetic resonance) spectroscopy revealed that TPS1-2a and TPS1-2b were homogalacturonan (HG) pectins consisting of a backbone of 1,4-linked α-d-galacturonic acid (GalA) residues with 28.4% and 26.1% of carboxyl groups as methyl ester, respectively. The immunological assay results demonstrated that TPS1-2, which consisted mainly of HG pectins, showed phagocytosis-enhancing activity in HL-60 cells

School Climate, Loneliness, and Problematic Online Game Use Among Chinese Adolescents: The Moderating Effect of Intentional Self-Regulation

Evidently, the school climate is important in reducing adolescent problematic online game use (POGU); however, the mechanism accounting for this association remains largely unknown. This study examined whether loneliness mediated the link between school climate and adolescent POGU and whether this mediating process was moderated by adolescent intentional self-regulation. To this end, self-report questionnaires were distributed. Participants were 500 12–17-years-old Chinese adolescents (Meanage = 13.59 years, 50.60% male). After controlling for adolescents' gender, age, family socioeconomic status, and self-esteem, the results showed that the negative association between school climate and adolescent POGU was partially mediated by loneliness. Moreover, this indirect link was stronger for adolescents with low intentional self-regulation than for those with high intentional self-regulation. These findings highlight loneliness as a potential mechanism linking school climate to adolescent POGU and provide guidance for the development of effective interventions for addressing the adverse effects of a negative school climate

AP205 VLPs based on dimerized capsid proteins accommodate RBM domain of SARS-CoV-2 and serve as an attractive vaccine candidate

COVID-19 is a novel disease caused by SARS-CoV-2 which has conquered the world rapidly resulting in a pandemic that massively impacts our health, social activities, and economy. It is likely that vaccination is the only way to form “herd immunity” and restore the world to normal. Here we developed a vaccine candidate for COVID-19 based on the virus-like particle AP205 displaying the spike receptor binding motif (RBM), which is the major target of neutralizing antibodies in convalescent patients. To this end, we genetically fused the RBM domain of SARS-CoV-2 to the C terminus of AP205 of dimerized capsid proteins. The fused VLPs were expressed in E. coli, which resulted in insoluble aggregates. These aggregates were denatured in 8 M urea followed by refolding, which reconstituted VLP formation as confirmed by electron microscopy analysis. Importantly, immunized mice were able to generate high levels of IgG antibodies recognizing eukaryotically expressed receptor binding domain (RBD) as well as spike protein of SARS-CoV-2. Furthermore, induced antibodies were able to neutralize SARS-CoV-2/ABS/NL20. Additionally, this vaccine candidate has the potential to be produced at large scale for immunization programs

Exploring atherosclerosis imaging with contrast-enhanced MRI using PEGylated ultrasmall iron oxide nanoparticles

Plaque rupture is a critical concern due to its potential for severe outcomes such as cerebral infarction and myocardial infarction, underscoring the urgency of noninvasive early diagnosis. Magnetic resonance imaging (MRI) has gained prominence in plaque imaging, leveraging its noninvasiveness, high spatial resolution, and lack of ionizing radiation. Ultrasmall iron oxides, when modified with polyethylene glycol, exhibit prolonged blood circulation and passive targeting toward plaque sites, rendering them conducive for MRI. In this study, we synthesized ultrasmall iron oxide nanoparticles of approximately 3 nm via high-temperature thermal decomposition. Subsequent surface modification facilitated the creation of a dual-modality magnetic resonance/fluorescence probe. Upon intravenous administration of the probes, MRI assessment of atherosclerotic plaques and diagnostic evaluation were conducted. The application of Flash-3D sequence imaging revealed vascular constriction at lesion sites, accompanied by a gradual signal amplification postprobe injection. T1-weighted imaging of the carotid artery unveiled a progressive signal ratio increase between plaques and controls within 72 h post-administration. Fluorescence imaging of isolated carotid arteries exhibited incremental lesion-to-control signal ratios. Additionally, T1 imaging of the aorta demonstrated an evolving signal enhancement over 48 h. Therefore, the ultrasmall iron oxide nanoparticles hold immense promise for early and noninvasive diagnosis of plaques, providing an avenue for dynamic evaluation over an extended time frame

Change of temperature field around different drainage structures in cold region tunnel based on model testing

Abstract Improper layout of drainage structures and inadequate insulation measures in cold tunnels can result in varying degrees of frost formation during operation. This study focuses on the Hongtoushan highway tunnel as an example, where the distribution characteristics of the temperature field around the lower drainage structure under different arrangements are investigated through indoor model testing. The results indicate that there is a significant hysteresis phenomenon in temperature changes across the cross-section as the burial depth increases. With an increase in the burial depth of the surrounding rock, the hysteresis time of temperature changes gradually elongates. The temperature variation pattern can be approximated by a cubic polynomial. In the vertical section, as the tunnel depth increases, the temperature of the surrounding rock in the lower part of the tunnel gradually rises while the amplitude of temperature change diminishes. The temperature near the centerline is relatively lower compared to the sides, where the temperature gradually increases moving away from the centerline