Epitope Profiling Reveals the Critical Antigenic Determinants in SARS-CoV-2 RBD-Based Antigen.

The ongoing COVID-19 pandemic caused by SARS-CoV-2 is a huge public health crisis for the globe. The receptor-binding domain (RBD) of SARS-CoV-2 spike (S) protein plays a vital role in viral infection and serves as a major target for developing neutralizing antibodies. In this study, the antibody response to the RBD of SARS-CoV-2 S protein was analyzed by a panel of sera from animals immunized with RBD-based antigens and four linear B-cell epitope peptides (R345, R405, R450 and R465) were revealed. The immunogenicity of three immunodominant peptides (R345, R405, R465) was further accessed by peptide immunization in mice, and all of them could induced potent antibody response to SARS-CoV-2 S protein, indicating that the three determinants in the RBD were immunogenic. We further generated and characterized monoclonal antibodies (15G9, 12C10 and 10D2) binding to these epitope peptides, and finely mapped the three immunodominant epitopes using the corresponding antibodies. Neutralization assays showed that all three monoclonal antibodies had neutralization activity. Results from IFA and western blotting showed that 12C10 was a cross-reactive antibody against both of SARS-CoV-2 and SARS-CoV. Results from conservative and structural analysis showed that 350VYAWN354 was a highly conserved epitope and exposed on the surface of SARS-CoV-2 S trimer, whereas 473YQAGSTP479 located in the receptor binding motif (RBM) was variable among different SARS-CoV-2 strains. 407VRQIAP412 was a highly conserved, but cryptic epitope shared between SARS-CoV-2 and SARS-CoV. These findings provide important information for understanding the humoral antibody response to the RBD of SARS-CoV-2 S protein and may facilitate further efforts to design SARS-CoV-2 vaccines and the target of COVID-19 diagnostic.

Correction to: Well­Being Reduces COVID­19 Anxiety: A Three­Wave Longitudinal Study in China.

[This corrects the article DOI: 10.1007/s10902-021-00385-2.].

Well-Being Reduces COVID-19 Anxiety: A Three-Wave Longitudinal Study in China.

The coronavirus disease 2019 (COVID-19) pandemic threatens human beings' livelihoods and mental health, which lowers their well-being and gives rise to anxiety. This study examines whether there is a causal relationship (and, if so, in which direction) between people's well-being and COVID-19 anxiety. Two hundred and twenty-two participants (54.50% female, M age = 31.53, SD = 8.17) from 26 provinces of China completed measures of subjective well-being (SWB) and COVID-19 anxiety at three key nodes of the development of COVID-19 in China. The results showed that people's SWB and COVID-19 anxiety fluctuated with the peak (T1), decline (T2), and trough stages (T3) of the COVID-19 pandemic. Meanwhile, the cross-lagged analysis showed that the participants' SWB at T0 (pre-pandemic stage; the base level of SWB) and T1 could significantly predict their COVID-19 anxiety at T1 and T2 respectively. However, SWB at T2 was not associated with the COVID-19 anxiety at T3. Furthermore, COVID-19 anxiety could not predict subsequent SWB from T1 to T3. The current findings contribute to clarifying the causal relationship between well-being and anxiety through the development of epidemics, as well as finding ways to alleviate people's COVID-19 anxiety. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10902-021-00385-2.

Development of a Colloidal Gold-Based Immunochromatographic Strip for Rapid Detection of Severe Acute Respiratory Syndrome Coronavirus 2 Spike Protein.

The outbreak and worldwide pandemic of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have a significant impact on global economy and human health. In order to reduce the disease spread, 16 monoclonal antibodies (McAbs) again SARS-CoV-2 were generated by immunized mice with the spike protein receptor binding domain (RBD), which was expressed in Chinese hamster ovary cell (CHO). A colloidal gold-based immunochromatographic strip was developed with two McAbs to detect SARS-CoV-2 spike protein, which can play a potential role in monitoring vaccine quality. The strip is highly specific, detecting only SARS-CoV-2 spike protein, and does not show any non-specific reactions with syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and other coronavirus and influenza viruses. The strip detected subunit vaccine in our laboratory with a detection limit of spike protein of 62.5 ng/mL. This strip provides an effective method in monitoring vaccine quality by detecting the antigen content of spike protein.