The influence mechanism of Real-Time Online Education Platform on Learner User Behavior (preprint)

The global outbreak of COVID-19 has triggered revolutionary changes in the field of education, especially the rise of real-time online education platform. The purpose of this paper is to explore the reasons of learner users' satisfaction and how to influence the willingness to continue using. Firstly, this paper combines the success model of information systems to construct a model of influencing factors of learner users' satisfaction about real-time online education platforms. Secondly, a questionnaire survey was conducted on 670 learners of China's real-time online education platform, then the structural equation model was used to analyze the main influencing factors of learners' satisfaction and how to influence the willingness to continue using real-time online education platform. The paper found that the professionalism and honesty of teacher quality, the usefulness, abundance, and appropriateness of content quality, as well as the technical and convenient feature of platform quality that predicted learner satisfaction, which has a positive impact on the willingness to continue using. The research provided a series of design strategies and improvement suggestions to improve the learner experience of real-time online education platform.

Competitive fitness and homologous recombination of SARS-CoV-2 variants of concern (preprint)

SARS-CoV-2 variants continue to emerge and cocirculate in humans and wild animals. The factors driving the emergence and replacement of novel variants and recombinants remain incompletely understood. Herein, we comprehensively characterized the competitive fitness of SARS-CoV-2 wild type (WT) and three variants of concern (VOCs), Alpha, Beta and Delta, by coinfection and serial passaging assays in different susceptible cells. Deep sequencing analyses revealed cell-specific competitive fitness: the Beta variant showed enhanced replication fitness during serial passage in Caco-2 cells, whereas the WT and Alpha variant showed elevated fitness in Vero E6 cells. Interestingly, a high level of neutralizing antibody sped up competition and completely reshaped the fitness advantages of different variants. More importantly, single clone purification identified a significant proportion of homologous recombinants that emerged during the passage history, and immune pressure reduced the frequency of recombination. Interestingly, a recombination hot region located between nucleotide sites 22995 and 28866 of the viral genomes could be identified in most of the detected recombinants. Our study not only profiled the variable competitive fitness of SARS-CoV-2 under different conditions, but also provided direct experimental evidence of homologous recombination between SARS-CoV-2 viruses, as well as a model for investigating SARS-CoV-2 recombination.

Activation of the NLRP1 Inflammasome and Its Role in Transmissible Gastroenteritis Coronavirus Infection.

The inflammasome pathway is a critical early response mechanism of the host that detects pathogens, initiates the production of inflammatory cytokines, and recruits effector cells to the infection site. Nonetheless, the mechanism of inflammasome activation in coronavirus infection and its biological functions in host defense remain unclear. Transmissible gastroenteritis virus (TGEV), a member of the genus Alphacoronavirus, is a significant pathogen that mainly infects piglets and causes intestinal inflammation and inflammatory cell infiltration. Here, we investigated the mechanism of inflammasome activation in intestinal epithelial cells (IECs) infected with TGEV. We observed a substantial increase in interleukin 1ß (IL-1ß) and IL-18 levels in both IECs and TGEV-infected porcine intestinal tissues. Furthermore, TGEV infection resulted in increased activation of caspase-1 and the NLRP1 (NOD-like receptor [NLR]-containing pyrin domain [PYD]) inflammasome. Our findings revealed that TGEV infection impeded the interaction between porcine NLRP1 (pNLRP1) and porcine dipeptidyl peptidases 9 (pDPP9), yet it did not reduce the expression of pDPP9. Importantly, the ZU5 domain, not the function-to-find domain (FIIND) reported in human NLRP1, was identified as the minimal domain of pNLRP1 for pDPP9 binding. In addition, the robust type I IFN expression induced by TGEV infection also upregulated pNLRP1 expression and pNLRP1 itself acts as an interferon-stimulated gene to counteract TGEV infection. Our data demonstrate that pNLRP1 has antiviral capabilities against coronavirus infection, which highlights its potential as a novel therapeutic target for coronavirus antiviral therapy. IMPORTANCE Coronavirus primarily targets the epithelial cells of the respiratory and gastrointestinal tracts, leading to damage in both humans and animals. NLRP1 is a direct sensor for RNA virus infection which is highly expressed in epithelial barrier tissues. However, until recently, the precise molecular mechanisms underlying its activation in coronavirus infection and subsequent downstream events remained unclear. In this study, we demonstrate that the alphacoronavirus TGEV induces the production of IL-1ß and IL-18 and upregulates the expression of pNLRP1. Furthermore, we found that pNLRP1 can serve as an interferon-stimulated gene (ISG) to inhibit the infection of enterovirus TGEV. Our research highlights the crucial role of NLRP1 as a regulator of innate immunity in TGEV infection and shows that it may serve as a potential therapeutic target for the treatment of coronavirus infection.

Glycyrrhizin inhibits swine acute diarrhea syndrome coronavirus infection via the HMGB1/TLR4/JNK signal pathway

Swine acute diarrhea syndrome coronavirus (SADS-CoV), a newly discovered enteric coronavirus, is the etiological agent that causes severe clinical diarrhea and intestinal pathological damage in piglets. In this study, Vero E6 and IPI-2I cells were pretreated with different concentrations of glycyrrhizin (GLY) for 2 hours, and then infected with different concentrations of SADSCoV, aiming to investigate the inhibitory effect of GLY on SADS-CoV. Western blot and TCID50 results revealed a significantly decreased N protein expression and viral titer, indicating that GLY can inhibit the infection of SADS-CoV. Vero E6 and IPI-2I cells were pretreated with different concentrations of GLY for 2 hours and infected with SADS-CoV. Western blot results showed that when the concentration of GLY was 0.8 mmol/L, the expression of N protein decreased significantly, indicating that GLY inhibited the invasion of the virus. At first, cells were treated with 0.4 mmol/L GLY, and cell samples were collected at 2 hours, 6 hours and 12 hours after being infected with SADS-CoV for analysis, and the expression of N protein were found to be significantly reduced at all points, indicating that GLY had a significant inhibitory effect on the replication of the virus. GLY is a competitive inhibitor of high mobility group box 1 (HMGB1), and the receptors of HMGB1 mainly include TLR4 and RAGE. Based on this fact, the mutant plasmid at the key sites of HMGB1 (C45S, C106S, C45/106S) and the siRNA of the RAGE receptor were transfected to Vero E6 cells and infected with SADS-CoV, and the cell supernatant and samples were harvested. The western blot and TCID50 results showed that the expression of N protein and the virus titer were decreased, suggesting that GLY exerts its function by affecting the binding of HMGB1/TLR4/RAGE during SADS-CoV infection. To further explore the signaling pathway through which GLY functions, Vero E6 and IPI-2I cells were inoculated with SADS-CoV, and cell samples were harvested, western blot was used to detect the changes of MAPK proteins. The results showed that the protein expression levels of p-p38, p-JNK and p-ERK were up-regulated in the early and late stages, indicating that the MAPK pathway was activated by SADS-CoV infection. Vero E6 and IPI-2I were pretreated with different concentrations of GLY and TLR4 inhibitor TAK for 2 hours and infected with SADS-CoV. Protein samples were harvested and analysed by western blot which showed a decreased p-JNK and N proteins, while other proteins showed no significant changes. These results indicated that GLY and TAK regulated the phosphorylation of JNK but did not regulate the phosphorylation of p38 and ERK. Also, Vero E6 cells were treated with HMGB1 antibody, the siRNA of HMGB1 and HMGB1 mutants plasmid, and infected with SADS-CoV. Protein samples were harvested, western blot results showed that phosphorylation of JNK decreased, indicating that HMGB1 affected JNK phosphorylation. Finally, Vero E6 and IPI-2I cells were pretreated with different concentrations of JNK inhibitor SP600125 to infect SADS-CoV, western blot, TCID50 and IFA results showed that the expression of N protein and virus titer, as well as virus replication were reduced, indicating that SP600125 inhibited virus replication. In conclusion, our results revealed that GLY can inhibit in vitro replication of SADS- CoV, mainly through the HMGB1/TLR4/JNK signaling pathway. The discovery of this pathway provides theoretical support for the research of novel anti-SADS-CoV drugs.

The dyadic effects of social support on anxiety among family members during COVID-19: The mediating role of perceived family resilience.

Families have been suffering from huge financial loss and psychological distress due to the COVID-19 pandemic. Most existing studies investigated the protective factors for anxiety at the individual level, while understandings from the perspective of family dyadic level were left unknown. Considering that social support could serve as a protective factor to reduce anxiety both at individual level and at dyadic level, the present study adopted dyadic data analysis approach to tackle this puzzle. In total, 2512 Chinese parent-adolescent dyads completed a survey with scales of anxiety, social support, and perceived family resilience on July 31 and August 1 of 2021. Results showed that: (1) adolescents' perceived social support had significant actor and partner effects on their own and parents' anxiety, whereas parents' perceived social support only had a significant actor effect on their own anxiety and (2) the actor mediating effects of social support on anxiety via one's own perceived family resilience were found in both adolescents and parents, and a partner mediating effect of adolescents' social support was significantly associated with parents' anxiety through parents' perceived family resilience. Findings emphasize that interventions aiming at increasing adolescents' support resources could generate a significant effect on reducing anxiety.

Entangling of Peptide Nanofibers Reduces the Invasiveness of SARS-CoV-2.

The viral spike (S) protein on the surface of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to angiotensin-converting enzyme 2 (ACE2) receptors on the host cells, facilitating its entry and infection. Here, functionalized nanofibers targeting the S protein with peptide sequences of IRQFFKK, WVHFYHK and NSGGSVH, which are screened from a high-throughput one-bead one-compound screening strategy, are designed and prepared. The flexible nanofibers support multiple binding sites and efficiently entangle SARS-CoV-2, forming a nanofibrous network that blocks the interaction between the S protein of SARS-CoV-2 and the ACE2 on host cells, and efficiently reduce the invasiveness of SARS-CoV-2. In summary, nanofibers entangling represents a smart nanomedicine for the prevention of SARS-CoV-2.

Octyl gallate targeting the 3C-like protease exhibits highly efficient antiviral activity against swine enteric coronavirus PEDV.

Infection with porcine epidemic diarrhea virus (PEDV) causes severe watery diarrhea in newborn piglets, leading to substantial financial losses for the swine industry. In this study, we screened small molecule drugs targeting 3 C-like protease (3CLpro) by molecular docking, and further evaluated the antiviral activity of the screened drugs against PEDV. Results showed that octyl gallate (OG), a widely used food additive, exhibited strong binding affinity with the 3CLpro active sites of PEDV. Bio-layer interferometry and fluorescence resonance energy transfer revealed that OG directly interacts with PEDV 3CLpro (KD = 549 nM) and inhibits 3CLpro activity (IC50 = 22.15 µM). OG showed a strong inhibition of PEDV replication in vitro. Virus titers were decreased by 0.58 and 0.71 log10 TCID50/mL for the CV777 and HM2017 strains, respectively. In vivo, all piglets in the PEDV-infected group died at 48 h post-infection (hpi), while 75% of piglets in the OG treatment group showed significant relief from the clinical symptoms, pathological damage, and viral loads in the jejunum and ileum. Moreover, the western blotting results showed that OG also has strong antiviral activity against other swine enteric coronaviruses, including transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and swine acute diarrhea syndrome coronavirus (SADS-CoV). Our findings revealed that OG could be developed as a novel antiviral drug against PEDV. The OG exhibited a potential broad-spectrum antiviral drug for control of other swine enteric coronaviruses.

UDCA May Promote COVID-19 Recovery: A Cohort Study with AI-Aided Analysis (preprint)

To investigate the impact of ursodeoxycholic acid (UDCA) treatment on the clinical outcome of mild and moderate COVID-19 cases, a retrospective analysis was conducted to evaluate the efficacy of UDCA on patients diagnosed with COVID-19 during the peak of the Omicron outbreak in China. This study presents promising results, demonstrating that UDCA significantly reduced the time to Body Temperature Recovery after admission and a higher daily dose seems to be associated with a better outcome without observed safety concerns. We also introduced VirtualBody, a physiologically plausible artificial neural network model, to generate an accurate depiction of the drug concentration-time curve individually, which represented the absorption, distribution, metabolism, and excretion of UDCA in each patient. It exhibits exceptional performance in modeling the complex PK-PD profile of UDCA, characterized by its endogenous and enterohepatic cycling properties, and further validates the effectiveness of UDCA as a treatment option from the drug exposure-response perspective. Our work highlights the potential of UDCA as a novel treatment option for periodic outbreaks of COVID-19 and introduces a new paradigm for PK-PD analysis in retrospective studies to provide evidence for optimal dosing strategies.

Cold Exposure-Induced Up-Regulation of Hsp70 Positively Regulates PEDV mRNA Synthesis and Protein Expression In Vitro.

Porcine epidemic diarrhea (PED) is a highly contagious, intestinal infectious disease caused by porcine epidemic diarrhea virus (PEDV). PEDV as an emerging and re-emerging epizootic virus of swine causes substantial economic losses to the pig industry in China and other countries. In China, the occurrence of PED shows significant seasonal variations, usually outbreak during the winter season. The epidemic characteristics of PED may be highly correlated with the changes of ambient temperature. However, molecular mechanism on the seasonal occurrence of PED still remains unclear. It has been widely observed that low ambient temperature up-regulates the expression of host heat shock protein 70 (Hsp70). Here, we showed that nucleotide and protein levels of Hsp70 were up-regulated in the intestinal of cold exposed pig and cold exposed Vero E6 cells. We found that overexpression of Hsp70 could increase PEDV mRNA synthesis and protein expression in Vero E6 and IPEC-J2 cells, while the siRNAs mediated knockdown of Hsp70 and VER155008 mediated inhibition of Hsp70 resulted in inhibition of viral mRNA synthesis and protein expression in Vero E6 cells. These data suggested that Hsp70 positively regulated PEDV mRNA synthesis and protein expression, which being helpful for understanding the seasonality of PED epidemics and development of novel antiviral therapies in the future.

Real-World COPD Management Over 3 Years at the Community Health Service Center of Shanghai During the COVID-19 Pandemic in China.

Objective: To evaluate the real-world situation for the management of chronic obstructive pulmonary disease (COPD) and poorly controlled disease risk factors in the Chinese community. Methods: This retrospective multicentre study analysed data from COPDMICand MICHC in Shanghai Songjiang District, Shanghai, China. The differences in COPD Assessment Test (CAT), the modified Medical Research Council (mMRC) dyspnea scale, and the number of emergency cases, emergency visits, inpatient cases, and hospitalisations from January 2018 to December 2020 were analysed. The impact of coronavirus disease 2019 (COVID-19) on COPD management was also assessed. Results: For 2020 versus 2018, analysis of 468 COPD cases from COPDMIC matched with MICHC data showed significantly more patients with improved mMRC grades, significantly fewer emergency cases and emergency visits, and significantly fewer hospitalisation cases and hospitalisations. Differences in the number of emergency visits and hospitalisations per capita were statistically significant. Compared to GOLD 3-4, GOLD 1-2 patients showed significant improvements in CAT score, mMRC grade, the number of emergency visits and hospitalisations per capita. Treatment adherence from 2018 to 2020 was 25%, 29.1%, and 6.8%, and the proportion of medication regimens consistent with guidelines was 43.44%, 50.98%, and 71.87%, respectively. Higher treatment adherence resulted in significantly improved CAT scores and mMRC grades and fewer emergency department visits and hospitalisations per capita. Conclusion: Combined with remote management tools, patients with COPD achieved continuous improvement in symptoms and exacerbations over 3 years. In the context of COVID-19 prevention/control measures, improvements were significant for patients with GOLD 1-2 COPD but limited with GOLD 3-4. Pharmacologic treatment significantly improved clinical symptoms and reduced emergency visits and hospitalisations. Severe airflow limitation and poor adherence to pharmacologic treatment were important risk factors for lack of disease remission.

Autophagy is induced by swine acute diarrhea syndrome coronavirus through the cellular IRE1-JNK-Beclin 1 signaling pathway after an interaction of viral membrane-associated papain-like protease and GRP78.

Autophagy plays an important role in the infectious processes of diverse pathogens. For instance, cellular autophagy could be harnessed by viruses to facilitate replication. However, it is still uncertain about the interplay of autophagy and swine acute diarrhea syndrome coronavirus (SADS-CoV) in cells. In this study, we reported that SADS-CoV infection could induce a complete autophagy process both in vitro and in vivo, and an inhibition of autophagy significantly decreased SADS-CoV production, thus suggesting that autophagy facilitated the replication of SADS-CoV. We found that ER stress and its downstream IRE1 pathway were indispensable in the processes of SADS-CoV-induced autophagy. We also demonstrated that IRE1-JNK-Beclin 1 signaling pathway, neither PERK-EIF2S1 nor ATF6 pathways, was essential during SADS-CoV-induced autophagy. Importantly, our work provided the first evidence that expression of SADS-CoV PLP2-TM protein induced autophagy through the IRE1-JNK-Beclin 1 signaling pathway. Furthermore, the interaction of viral PLP2-TMF451-L490 domain and substrate-binding domain of GRP78 was identified to activate the IRE1-JNK-Beclin 1 signaling pathway, and thus resulting in autophagy, and in turn, enhancing SADS-CoV replication. Collectively, these results not only showed that autophagy promoted SADS-CoV replication in cultured cells, but also revealed that the molecular mechanism underlying SADS-CoV-induced autophagy in cells.

Gasdermin D Inhibits Coronavirus Infection by Promoting the Noncanonical Secretion of Beta Interferon.

Pyroptosis, a programmed cell death, functions as an innate immune effector mechanism and plays a crucial role against microbial invasion. Gasdermin D (GSDMD), as the main pyroptosis effector, mediates pyroptosis and promotes releasing proinflammatory molecules into the extracellular environment through pore-forming activity, modifying inflammation and immune responses. While the substantial importance of GSDMD in microbial infection and cancer has been widely investigated, the role of GSDMD in virus infection, including coronaviruses, remains unclear. Enteric coronavirus transmissible gastroenteritis virus (TGEV) and porcine deltacoronavirus (PDCoV) are the major agents for lethal watery diarrhea in neonatal pigs and pose the potential for spillover from pigs to humans. In this study, we found that alphacoronavirus TGEV upregulated and activated GSDMD, resulting in pyroptosis after infection. Furthermore, the fragment of swine GSDMD from amino acids 242 to 279 (242-279 fragment) was required to induce pyroptosis. Notably, GSDMD strongly inhibited both TGEV and PDCoV infection. Mechanistically, the antiviral activity of GSDMD was mediated through promoting the nonclassical release of antiviral beta interferon (IFN-ß) and then enhancing the interferon-stimulated gene (ISG) responses. These findings showed that GSDMD dampens coronavirus infection by an uncovered GSDMD-mediated IFN secretion, which may present a novel target of coronavirus antiviral therapeutics. IMPORTANCE Coronaviruses, primarily targeting respiratory and gastrointestinal epithelia in vivo, have a serious impact on humans and animals. GSDMD, a main executioner of pyroptosis, is highly expressed in epithelial cells and involves viral infection pathogenesis. While the functions and importance of GSDMD as a critical regulator of inflammasome activities in response to intracellular bacterial infection have been extensively investigated, the roles of GSDMD during coronavirus infection remain unclear. We here show that alphacoronavirus TGEV triggered pyroptosis and upregulated GSDMD expression, while GSDMD broadly suppressed the infection of enteric coronavirus TGEV and PDCoV by its pore-forming activity via promoting unconventional release of IFN-ß. Our study highlights the importance of GSDMD as a regulator of innate immunity and may open new avenues for treating coronavirus infection.

The TGEV Membrane Protein Interacts with HSC70 To Direct Virus Internalization through Clathrin-Mediated Endocytosis.

Coronavirus membrane protein is a major component of the viral envelope and plays a central role in the viral life cycle. Studies of the coronavirus membrane protein (M) have mainly focused on its role in viral assembly and budding, but whether M protein is involved in the initial stage of viral replication remains unclear. In this study, eight proteins in transmissible gastroenteritis virus (TGEV)-infected cells coimmunoprecipitated with monoclonal antibodies (MAb) against M protein in PK-15 cells, heat shock cognate protein 70 (HSC70), and clathrin were identified by matrix-assisted laser desorption ionization-tandem time of flight mass spectrometry (MALDI-TOF MS). Further studies demonstrated that HSC70 and TGEV M colocalized on the cell surface in early stages of TGEV infection; specifically, HSC70 bound M protein through its substrate-binding domain (SBD) and preincubation of TGEV with anti-M serum to block the interaction of M and HSC70 reduced the internalization of TGEV, thus demonstrating that the M-HSC70 interaction mediates the internalization of TGEV. Remarkably, the process of internalization was dependent on clathrin-mediated endocytosis (CME) in PK-15 cells. Furthermore, inhibition of the ATPase activity of HSC70 reduced the efficiency of CME. Collectively, our results indicated that HSC70 is a newly identified host factor involved in TGEV infection. Taken together, our findings clearly illustrate a novel role for TGEV M protein in the viral life cycle and present a unique strategy used by HSC70 to promote TGEV infection in which the interaction with M protein directs viral internalization. These studies provide new insights into the life cycle of coronaviruses. IMPORTANCE TGEV is the causative agent of porcine diarrhea, a viral disease that economically affects the pig industry in many countries. However, the molecular mechanisms underlying viral replication remain incompletely understood. Here, we provide evidence of a previously undescribed role of M protein in viral replication during early stages. We also identified HSC70 as a new host factor affecting TGEV infection. We demonstrate that the interaction between M and HSC70 directs TGEV internalization in a manner dependent on CME, thus revealing a novel mechanism for TGEV replication. We believe that this study may change our understanding of the first steps of infection of cells with coronavirus. This study should facilitate the development of anti-TGEV therapeutic agents by targeting the host factors and may provide a new strategy for the control of porcine diarrhea.

Intra- vs. inter-host evolution of SARS-CoV-2 driven by uncorrelated selection - The evolution thwarted (preprint)

In viral evolution, a new mutation has to proliferate within the host (Stage I) in order to be transmitted and then compete in the host population (Stage II). We now analyze the intra-host single nucleotide variants (iSNVs) in a set of 79 SARS-CoV-2 infected patients with most transmissions tracked. Here, every mutation has two measures: i) iSNV frequency within each individual host in Stage I; ii) occurrence among individuals ranging from 1 (private), 2-78 (public) to 79 (global) occurrences in Stage II. In Stage I, a small fraction of non-synonymous iSNVs are sufficiently advantageous to rise to a high frequency, often 100%. However, such iSNVs usually fail to become public mutations. Thus, the selective forces in the two stages of evolution are uncorrelated and, possibly, antagonistic. For that reason, successful mutants, including many VOCs (variants of concern), have to avoid being eliminated in Stage I when they first emerge. As a result, they may not have the transmission advantage to outcompete the dominant strains and, hence, are rare in the host population. Few of them could manage to slowly accumulate advantageous mutations to compete in Stage II. When they do, they would appear suddenly as in each of the 6 successive waves of SARS-CoV-2 strains. In conclusion, Stage I evolution, the gate-keeper, may contravene the long-term viral evolution and should be heeded in viral studies.

Interplay between swine enteric coronaviruses and host innate immune.

Swine enteric coronavirus (SeCoV) causes acute diarrhea, vomiting, dehydration, and high mortality in neonatal piglets, causing severe losses worldwide. SeCoV includes the following four members: transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), porcine delta coronavirus (PDCoV), and swine acute diarrhea syndrome coronavirus (SADS-CoV). Clinically, mixed infections with several SeCoVs, which are more common in global farms, cause widespread infections. It is worth noting that PDCoV has a broader host range, suggesting the risk of PDCoV transmission across species, posing a serious threat to public health and global security. Studies have begun to focus on investigating the interaction between SeCoV and its host. Here, we summarize the effects of viral proteins on apoptosis, autophagy, and innate immunity induced by SeCoV, providing a theoretical basis for an in-depth understanding of the pathogenic mechanism of coronavirus.

Compromised skin barrier induced by prolonged face mask usage during the COVID-19 pandemic and its remedy with proper moisturization.

BACKGROUND: Prolonged face mask usage, a daily practice for the public due to the COVID-19 pandemic, creates high levels of humidity underneath the mask, which may cause unexpected skin concerns. OBJECTIVE: To investigate the impact of repeated mask usage on the face by comparing skin properties inside and outside of the mask-covered areas. METHODS: A double-blinded, randomized, split-face clinical study was conducted with 21 healthy female participants who wore face masks at least 6 h every day for 1 week, with one side of their face treated with a moisturizer three times daily. On day 8, after 5 h of wearing the mask, skin properties (sebum, hydration, and trans-epidermal water loss [TEWL]) were evaluated at 15, 60, and 120 min post-mask removal, followed by barrier disruption and recovery assessment. RESULTS: Mask usage weakened stratum corneum (SC) on facial skin compared to uncovered areas, including reduced SC hydration (p < 0.02 at 15 min) and increased TEWL in response to tape stripping challenge (p < 0.03 after stripping). In addition, sebum production also increased after mask removal (p < 0.01 at 15 min). Notably, a daily moisturizer mitigated these effects by increasing SC hydration (p < 0.001) and improving SC resilience against barrier disruption. CONCLUSION: Daily prolonged usage of a facial mask, essential due to the COVID-19 situation, generated a high-humidity microenvironment and led to compromised SC, which was revealed by a barrier challenge technique. Moreover, proper facial moisturization may help to maintain skin homeostasis and prevent the barrier impairment caused by repeated mask usage.

Performance of spiral UTE-MRI of the lung in post-COVID patients.

Patients recovered from COVID-19 may develop long-COVID symptoms in the lung. For this patient population (post-COVID patients), they may benefit from longitudinal, radiation-free lung MRI exams for monitoring lung lesion development and progression. The purpose of this study was to investigate the performance of a spiral ultrashort echo time MRI sequence (Spiral-VIBE-UTE) in a cohort of post-COVID patients in comparison with CT and to compare image quality obtained using different spiral MRI acquisition protocols. Lung MRI was performed in 36 post-COVID patients with different acquisition protocols, including different spiral sampling reordering schemes (line in partition or partition in line) and different breath-hold positions (inspiration or expiration). Three experienced chest radiologists independently scored all the MR images for different pulmonary structures. Lung MR images from spiral acquisition protocol that received the highest image quality scores were also compared against corresponding CT images in 27 patients for evaluating diagnostic image quality and lesion identification. Spiral-VIBE-UTE MRI acquired with the line in partition reordering scheme in an inspiratory breath-holding position achieved the highest image quality scores (score range = 2.17-3.69) compared to others (score range = 1.7-3.29). Compared to corresponding chest CT images, three readers found that 81.5% (22 out of 27), 81.5% (22 out of 27) and 37% (10 out of 27) of the MR images were useful, respectively. Meanwhile, they all agreed that MRI could identify significant lesions in the lungs. The Spiral-VIBE-UTE sequence allows for fast imaging of the lung in a single breath hold. It could be a valuable tool for lung imaging without radiation and could provide great value for managing different lung diseases including assessment of post-COVID lesions.

SMART: A Swing-Assisted Multiplexed Analyzer for Point-of-Care Respiratory Tract Infection Testing.

Respiratory tract infections such as the ongoing coronavirus disease 2019 (COVID-19) has seriously threatened public health in the last decades. The experience of fighting against the epidemic highlights the importance of user-friendly and accessible point-of-care systems for nucleic acid (NA) detection. To realize low-cost and multiplexed point-of-care NA detection, a swing-assisted multiplexed analyzer for point-of-care respiratory tract infection testing (SMART) was proposed to detect multiple respiratory tract pathogens using visible loop-mediated isothermal amplification. By performing hand-swing movements to generate acceleration force to distribute samples into reaction chambers, the design of the SMART system was greatly simplified. By using different format of chips and integrating into a suitcase, this system can be applied to on-site multitarget and multi-sample testing. Three targets including the N and Orf genes of SARS-CoV-2 and the internal control were simultaneously analyzed (limit of detection: 2000 copies/mL for raw sample; 200 copies/mL for extracted sample). Twenty-three clinical samples with eight types of respiratory bacteria and twelve COVID-19 clinical samples were successfully detected. These results indicate that the SMART system has the potential to be further developed as a versatile tool in the diagnosis of respiratory tract infection.

Innate Immune Evasion of Porcine Epidemic Diarrhea Virus through Degradation of the FBXW7 Protein via the Ubiquitin-Proteasome Pathway.

Porcine epidemic diarrhea virus (PEDV) causes a porcine disease associated with swine epidemic diarrhea. Different antagonistic strategies have been identified, and the mechanism by which PEDV infection impairs the production of interferon (IFN) and delays the activation of the IFN response to escape host innate immunity has been determined, but the pathogenic mechanisms of PEDV infection remain enigmatic. Our preliminary results revealed that endogenous F-box and WD repeat domain-containing 7 (FBXW7) protein, the substrate recognition component of the SCF-type E3 ubiquitin ligase, is downregulated in PEDV-infected Vero E6 cells, according to the results from an isobaric tags for relative and absolute quantification (iTRAQ) analysis. Overexpression of FBXW7 in target cells makes them more resistant to PEDV infection, whereas ablation of FBXW7 expression by small interfering RNA (siRNA) significantly promotes PEDV infection. In addition, FBXW7 was verified as an innate antiviral factor capable of enhancing the expression of RIG-I and TBK1, and it was found to induce interferon-stimulated genes (ISGs), which led to an elevated antiviral state of the host cells. Moreover, we revealed that PEDV nonstructural protein 2 (nsp2) interacts with FBXW7 and targets FBXW7 for degradation through the K48-linked ubiquitin-proteasome pathway. Consistent with the results proven in vitro, FBXW7 reduction was also confirmed in different intestinal tissues from PEDV-infected specific-pathogen-free (SPF) pigs. Taken together, the data indicated that PEDV has evolved with a distinct antagonistic strategy to circumvent the host antiviral response by targeting the ubiquitin-proteasome-mediated degradation of FBXW7. Our findings provide novel insights into PEDV infection and pathogenesis. IMPORTANCE To counteract the host antiviral defenses, most viruses, including coronaviruses, have evolved with diverse strategies to dampen host IFN-mediated antiviral response, by interfering with or evading specific host regulators at multiple steps of this response. In this study, a novel antagonistic strategy was revealed showing that PEDV infection could circumvent the host innate response by targeted degradation of endogenous FBXW7 in target cells, a process that was verified to be a positive modulator for the host innate immune system. Degradation of FBXW7 hampers host innate antiviral activation and facilitates PEDV replication. Our findings reveal a new mechanism exploited by PEDV to suppress the host antiviral response.