Vaccination with Span, an antigen guided by SARS-CoV-2 S protein evolution, protects against challenge with viral variants in mice

SARS-CoV-2 continues to accumulate mutations to evade immunity, leading to breakthrough infections after vaccination. How researchers can anticipate the evolutionary trajectory of the virus in advance in the design of next-generation vaccines requires investigation. Here, we performed a comprehensive study of 11,650,487 SARS-CoV-2 sequences, which revealed that the SARS-CoV-2 spike (S) protein evolved not randomly but into directional paths of either high infectivity plus low immune resistance or low infectivity plus high immune resistance. The viral infectivity and immune resistance of variants are generally incompatible, except for limited variants such as Beta and Kappa. The Omicron variant has the highest immune resistance but showed high infectivity in only one of the tested cell lines. To provide cross-clade immunity against variants that undergo diverse evolutionary pathways, we designed a new pan-vaccine antigen (Span). Span was designed by analyzing the homology of 2675 SARS-CoV-2 S protein sequences from the NCBI database before the Delta variant emerged. The refined Span protein harbors high-frequency residues at given positions that reflect cross-clade generality in sequence evolution. Compared with a prototype wild-type (Swt) vaccine, which, when administered to mice, induced serum with decreased neutralization activity against emerging variants, Span vaccination of mice elicited broad immunity to a wide range of variants, including those that emerged after our design. Moreover, vaccinating mice with a heterologous Span booster conferred complete protection against lethal infection with the Omicron variant. Our results highlight the importance and feasibility of a universal vaccine to fight against SARS-CoV-2 antigenic drift.

Comparison of Online and face-to-face Learning Experience: A Case Study of Higher Vocational Hospitality Education in China

Online learning has attracted attention from academics and educators for several decades. Online learning plays a significant role in many educational institutions, including higher vocational hospitality colleges, especially during the COVID-19 outbreak. However, students' learning experience of online and face-to-face higher vocational hospitality courses is scarcely understood. To fill this research gap, a higher vocational college in China is selected as a case study to conduct a comparative study. Results show that students scored higher in face-to-face hospitality course learning experience than in online courses. Theoretical and practical implications are provided accordingly.

Establishment and validation of competitive ELISA for detecting blocking activity of monoclonal antibody against SARS-CoV-2 RBD

Objective: To establish and verify a competitive ELISA method for the detection of blocking activity of monoclonal antibody against SARS-CoV-2 RBD, and to compare the results by correlation analysis with that of live virus neutralization activity measured by the plaque reduction neutralization test (PRNT). Methods: Using RBD-Fc as coating antigen, ACE2-His and anti-SARS-CoV-2 RBD monoclonal antibodies were added to competitively bind to RBD. Anti-6×his antibody labeled with horseradish peroxidase was used as the secondary antibody. The competitive ELISA method detecting the ability of McAb to block the binding of RBD to ACE2 was established. The specificity, relative accuracy, precision, linearity and range of the method were verified. Seven monoclonal antibodies against SARS-CoV-2 RBD were detected by this method. The results were compared with PRNT method, and correlation analysis was performed. Results: The blocking activity of the relevant anti-SARS-CoV-2 RBD monoclonal antibody on RBD and ACE2 protein can be effectively detected using the established competitive ELISA method. The blocking ability of McAb was dose-dependent and conformed to the four-parameter equation. The samples with theoretical titers of 64%, 80%, 100%, 125% and 156% were determined for 10 times, and the relative bias was within ±20%. The logarithm (abscissa) of theoretical potency value was used for linear regression to the logarithm (ordinate) of the corresponding titer determination value. The regression equation was y=1.156x-0.021 3, in which the slope was between 0.8 and 1.25, meaning good relative accuracy. The geometric coefficient of variation (GCV%) of the relative titers of each titer level were 2.6%, 5.2%, 3.6%, 3.4% and 10.2%, respectively, all of which were less than 20% with good precision. The correlation coefficient of linear regression equation was 0.985, meeting the requirements. The relative accuracy, intermediate precision and linearity of the method all met the requirements of the titer level range was 64%~156%. The detection results of the blocking activity of the 7 RBD monoclonal antibodies showed good correlation with the results of the live virus neutralization activity measured by the PRNT method. Conclusion: A competitive ELISA method for the detection of anti-SARS-CoV-2 RBD monoclonal antibody has been successfully established. The method has satisfied specificity, accuracy, precision and linearity. The results had a good correlation with that by PRNT method. It can be used to indirectly evaluate the neutralizing activity of related SARS-CoV-2 monoclonal antibodies against the live viruses.

[Suggestions for thoracic surgery clinical practice in non-epidemic area of 2019 coronavirus disease].

In this paper, the mechanism of destroying human alveolar epithelial cells and pulmonary tissue by 2019 novel coronavirus (2019-nCoV) was discussed firstly. There may be multiple mechanisms including killing directly the target cells and hyperinflammatory responses. Secondly, the clinical features, CT imaging, short-term and long-term pulmonary function damage of the 2019 coronavirus disease (COVID-19) was analyzed. Finally, some suggestions for thoracic surgery clinical practice in non-epidemic area during and after the epidemic of COVID-19 were provided, to help all the thoracic surgery patients receive active and effective treatment.

[Epidemiological investigation on a cluster epidemic of COVID-19 in a collective workplace in Tianjin].

Objective: To investigate and analysis the epidemiological characteristics of a cluster epidemic of COIVD-19 in a collective workplace in Tianjin, evduate the prevention and control measures based on limited evidence and experience in early period of COVID-19 epidemic. Methods: Descriptive research method was used to describe the distribution and other epidemiological characteristics of the cluster cases of COVID-19. Results: Since the onset of the first index case on January 15, ten confirmed COVID-19 cases had occurred in the workplace, and the epidemic had spread from the workplace to 4 families, infecting 7 family members. The median age of 17 cases was 55 (19-79) years. All the 10 employee cases were males, and in the family cases, 3 were males and 4 were females. Of the employee cases, 8 worked in CW workshop and 2 worked in administrative office building. The median exposure-onset interval of all the cases was 4 days, and the median exposure-onset interval was 4.5 days in the employee cases and 4 days in the family cases. The median onset-medical care seeking interval was 4 days in the non-isolated cases, 2.5 days in the cases with home isolation after onset, and 0.5 day in the cases with home isolation before onset. Conclusions: The clustering of COVID-19 cases was observed in this workplace in Tianjin, which affected 4 families. In the early stage of the epidemic, accurate and rapid blocking and control measures can completely prevent the large-scale spread of COVID-19.