Identification and Comparison of the Sialic Acid-Binding Domain Characteristics of Avian Coronavirus Infectious Bronchitis Virus Spike Protein.

Infectious bronchitis virus (IBV) infections are initiated by the transmembrane spike (S) glycoprotein, which binds to host factors and fuses the viral and cell membranes. The N-terminal domain of the S1 subunit of IBV S protein binds to sialic acids, but the precise location of the sialic acid binding domain (SABD) and the role of the SABD in IBV-infected chickens remain unclear. Here, we identify the S1 N-terminal amino acid (aa) residues 19 to 227 (209 aa total) of IBV strains SD (GI-19) and GD (GI-7), and the corresponding region of M41 (GI-1), as the minimal SABD using truncated protein histochemistry and neuraminidase assays. Both α-2,3- and α-2,6-linked sialic acids on the surfaces of CEK cells can be used as attachment receptors by IBV, leading to increased infection efficiency. However, 9-O acetylation of the sialic acid glycerol side chain inhibits IBV S1 and SABD protein binding. We further constructed recombinant strains in which the S1 gene or the SABD in the GD and SD genomes were replaced with the corresponding region from M41 by reverse genetics. Infecting chickens with these viruses revealed that the virulence and nephrotropism of rSDM41-S1, rSDM41-206, rGDM41-S1, and rGDM41-206 strains were decreased to various degrees compared to their parental strains. A positive sera cross-neutralization test showed that the serotypes were changed for the recombinant viruses. Our results provide insight into IBV infection of host cells that may aid vaccine design. IMPORTANCE To date, only α-2,3-linked sialic acid has been identified as a potential host binding receptor for IBV. Here, we show the minimum region constituting the sialic acid binding domain (SABD) and the binding characteristics of the S1 subunit of spike (S) protein of IBV strains SD (GI-19), GD (GI-7), and M41 (GI-1) to various sialic acids. The 9-O acetylation modification partially inhibits IBV from binding to sialic acid, while the virus can also bind to sialic acid molecules linked to host cells through an α-2,6 linkage, serving as another receptor determinant. Substitution of the putative SABD from strain M41 into strains SD and GD resulted in reduced virulence, nephrotropism, and a serotype switch. These findings suggest that sialic acid binding has diversified during the evolution of γ-coronaviruses, impacting the biological properties of IBV strains. Our results offer insight into the mechanisms by which IBV invades host cells.

A psychological behavioral survey among medical students during the outbreak of Coronavirus disease 2019

Objective: To evaluate the psychological status of medical students after the outbreak of coronavirus disease 2019 (COV1D - 19) in order to provide necessary psychological assistance. Methods The respondents were medical students from Zhongshan School of Medicine and Affiliated Hospitals of Sun Yat - scn University. A survey platform Wenjuanxing was used to design the questionnaire. The responding time ranged from Feb 1st 2020 to Feb 8th 2020. SPSS 25.0 and performed the binary Logistic multivariate regression analysis were used to investigate how demographic characteristics and other factors influence medical students' psychological status. Results The number of respondents was 1 244, and the valid samples were 1 209.55.1% of medical students checked the epidemic report one to three times per day. Most medical students did not suffer from depression or anxiety. only 0.7%-12.4% had symptoms for "more than half of the time", and 0.2%-5.4% had symptoms "nearly every day". Among students with symptoms, 24.5% relieved within one week, 4.8% within two weeks and 0.8% within three weeks, while only 6.3% had persistent symptoms. Suspending classes had no perceivable influence on psychological status in 37.6% of respondents and had only a little influence on 35.3% of them. The percentage of affected nudes was 32.6%, and that for females was 44.9% (f1/40.05). Undergraduate students had the least proportion (37.4%) of being psychologically influenced, while master students had the most proportion (411.7%), the difference was statistically significant (1/40.05). 56.5% of students with mild anxiety or depression tendency had psychological influence, while the percentage of students with moderate, moderate-severe, severe were 80.0%, 73.7%, and 85.7%, respectively. the difference was statistically significant (11/40.05). During the epidemic period, the active learners were less often affected than the students who did not study, the percentage being 38.0% and 44.5%, respectively, the difference was statistically significant (P<0.05"). Conclusion After the outbreak of COVID-19, the psychological status of medical students is normal, but the psychological behavior of a few medical students has undergone negative changes. High-risk groups need special psychological intervention. Counselors and class teachers should strengthen the contact with this class of students to avoid negative emotions from adversely affecting the psychological behavior of medical students.

Role of Stress Granules in Suppressing Viral Replication by the Infectious Bronchitis Virus Endoribonuclease.

Infectious bronchitis virus (IBV), a γ-coronavirus, causes the economically important poultry disease infectious bronchitis. Cellular stress response is an effective antiviral strategy that leads to stress granule (SG) formation. Previous studies suggested that SGs were involved in the antiviral activity of host cells to limit viral propagation. Here, we aimed to delineate the molecular mechanisms regulating the SG response to pathogenic IBV strain infection. We found that most chicken embryo kidney (CEK) cells formed no SGs during IBV infection and IBV replication inhibited arsenite-induced SG formation. This inhibition was not caused by changes in the integrity or abundance of SG proteins during infection. IBV nonstructural protein 15 (Nsp15) endoribonuclease activity suppressed SG formation. Regardless of whether Nsp15 was expressed alone, with recombinant viral infection with Newcastle disease virus as a vector, or with EndoU-deficient IBV, the Nsp15 endoribonuclease activity was the main factor inhibiting SG formation. Importantly, uridine-specific endoribonuclease (EndoU)-deficient IBV infection induced colocalization of IBV N protein/dsRNA and SG-associated protein TIA1 in infected cells. Additionally, overexpressing TIA1 in CEK cells suppressed IBV replication and may be a potential antiviral factor for impairing viral replication. These data provide a novel foundation for future investigations of the mechanisms by which coronavirus endoribonuclease activity affects viral replication. IMPORTANCE Endoribonuclease is conserved in coronaviruses and affects viral replication and pathogenicity. Infectious bronchitis virus (IBV), a γ-coronavirus, infects respiratory, renal, and reproductive systems, causing millions of dollars in lost revenue to the poultry industry worldwide annually. Mutating the viral endoribonuclease poly(U) resulted in SG formation, and TIA1 protein colocalized with the viral N protein and dsRNA, thus damaging IBV replication. These results suggest a new antiviral target design strategy for coronaviruses.

COVID-19 Shock, Financial Flexibility, and Hotels' Performance Nexus.

This study investigates the nexus of coronavirus disease 2019 (COVID-19) shock, financial flexibility (FF), and firm performance (FP) in Taiwan listed hotel firms. Quantile regression (QR) methods were used to analyze the data from Taiwan Stock Exchange listed hotel firms between 2020 Q1 and 2021 Q2. The results evidence that there is an inversed U-shaped linkage between FF and FP for the hotel industry. Additionally, FF has an inverted U-shaped effect on FP for the asset-light hotel firms for all quantiles except the 50th quantile. In addition, FF also has an inverted U-shaped impact on FP for the asset-heavy hotel firms in the 10th and 90th quantiles. A significant finding in this study is that there is a concave non-linear relationship between FF and FP, consistent with the law of diminishing marginal return. That is, with an increase in FF, the FP is on the rise; when FF exceeds the inflection point level, the FP begins to decline. Thus, a firm must ensure that the FF strategy it adopts must be the most efficient and effective, i.e., it must bring the trade-off between costs and benefits. The empirical results highlight the need for the hotel industry of Taiwan to take the rolling adjustment and optimization of FF after the COVID-19 pandemic for long-term sustainability.

A Gradient pH-Sensitive Polymer-Based Antiviral Strategy via Viroporin-Induced Membrane Acidification.

Lipid-membrane-targeting strategies hold great promise to develop broad-spectrum antivirals. However, it remains a big challenge to identify novel membrane-based targets of viruses and virus-infected cells for development of precision targeted approaches. Here, it is discovered that viroporins, viral-encoded ion channels, which have been reported to mediate release of hydrogen ions, trigger membrane acidification of virus-infected cells. Through development of a fine-scale library of gradient pH-sensitive (GPS) polymeric nanoprobes, the cellular membrane pH transitions are measured from pH 6.8-7.1 (uninfection) to pH 6.5-6.8 (virus-infection). In response to the subtle pH alterations, the GPS polymer with sharp response at pH 6.8 (GPS6.8 ) selectively binds to virus-infected cell membranes or the viral envelope, and even completely disrupts the viral envelope. Accordingly, GPS6.8 treatment exerts suppressive effects on a wide variety of viruses including SARS-CoV-2 through triggering viral-envelope lysis rather than affecting immune pathway or viability of host cells. Murine viral-infection models exhibit that supplementation of GPS6.8 decreases viral titers and ameliorates inflammatory damage. Thus, the gradient pH-sensitive nanotechnology offers a promising strategy for accurate detection of biological pH environments and robust interference with viruses.

Early clinical and CT features of COVID-19 and community-acquired pneumonia from a fever observation ward in Ningbo, China.

INTRODUCTION: We aimed to compare the early clinical manifestations, laboratory results and chest computed tomography (CT) images of COVID-19 patients with those of other community-acquired pneumonia (CAP) patients to differentiate CAP from COVID-19 before reverse transcription-polymerase chain reaction results are obtained. METHODS: The clinical and laboratory data and chest CT images of 51 patients were assessed in a fever observation ward for evidence of COVID-19 between January and February 2020. RESULTS: 24 patients had laboratory-confirmed COVID-19, whereas 27 individuals had negative results. No statistical difference in clinical features was found between COVID-19 and CAP patients, except for diarrhoea. There was a significant difference in lymphocyte and eosinophil counts between COVID-19 and CAP patients. In total, 22 (91.67%) COVID-19 patients had bilateral involvement and multiple lesions according to their lung CT images; the left lower lobe (87.50%) and right lower lobe (95.83%) were affected most often, and all lesions were located in the peripheral zones of the lung. The most common CT feature of COVID-19 was ground-glass opacity, found in 95.83% of patients, compared to 66.67% of CAP patients. CONCLUSION: Diarrhoea, lymphocyte counts, eosinophil counts and CT findings (e.g. ground-glass opacity) could help to distinguish COVID-19 from CAP at an early stage of infection, based on findings from our fever observation ward.

Are You Tired of Working amid the Pandemic? The Role of Professional Identity and Job Satisfaction against Job Burnout.

With the outbreak of novel coronavirus in 2019, most universities changed from traditional offline teaching to online teaching, which brought about a large amount of problems, including teachers' physical and mental problems. Because of teaching on the computer screen for a long period of time, the teacher lacks communication and can act casually. With long-term accumulation, the problem of teachers' job burnout has become increasingly serious. The main purpose of this study was to examine the influence of professional identity on job burnout during the period of the novel coronavirus. At the same time, this study also discussed the moderating effect of job satisfaction on professional identity and job burnout, and its relationship between job satisfaction and job burnout. During the peak period of the COVID-19 epidemic, we conducted an online survey-483 Chinese university teachers with online teaching experience completed the Teacher Professional Identity Scale, Job Satisfaction Scale, and Job Burnout Scale. The results of this study found professional identity and job satisfaction of university teachers to be significantly negative predictors of job burnout, with job satisfaction playing a moderating role between professional identity and job burnout. This study also confirmed that professional identity and job satisfaction are important factors affecting job burnout of university teachers. Therefore, this study proposed that schools should adopt more effective strategies to improve university teachers' professional identity and job satisfaction in order to reduce the practical problems of job burnout, ensure the effectiveness of online teaching, and maintain the sustainable development during the epidemic.