Pathogen-host adhesion between SARS-CoV-2 spike proteins from different variants and human ACE2 studied at single-molecule and single-cell levels.

The binding of the receptor binding domain (RBD) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein onto human angiotensin-converting enzyme 2 (ACE2) is considered as the first step for the virus to adhere onto the host cells during the infection. Here, we investigated the adhesion of spike proteins from different variants and ACE2 using single-molecule and single-cell force spectroscopy. We found that the unbinding force and binding probability of the spike protein from Delta variant to the ACE2 were the highest among the variants tested in our study at both single-molecule and single-cell levels. As the most popular variants, the Omicron variants have slightly higher unbinding force to the ACE2 than wild type. Molecular dynamics simulation showed that ACE2-RBD (Omicron BA.1) complex is destabilized by the E484A and Y505H mutations and stabilized by S477N and N501Y mutations, when compared with Delta variant. In addition, a neutralizing antibody, produced by immunization with wild type spike protein, could effectively inhibit the binding of spike proteins from wild type, Delta and Omicron variants (BA.1 and BA.5) onto ACE2. Our results provide new insight for the molecular mechanism of the adhesive interactions between spike protein and ACE2 and suggest that effective monoclonal antibody can be prepared using wild type spike protein against different variants.

Electrochemical Detection of a Few Copies of Unamplified SARS-CoV-2 Nucleic Acids by a Self-Actuated Molecular System.

The existing electrochemical biosensors lack controllable and intelligent merit to modulate the sensing process upon external stimulus, leading to challenges in analyzing a few copies of biomarkers in unamplified samples. Here, we present a self-actuated molecular-electrochemical system that consists of a tentacle and a trunk modification on a graphene microelectrode. The tentacle that contains a probe and an electrochemical label keeps an upright orientation, which increases recognition efficiency while decreasing the pseudosignal. Once the nucleic acids are recognized, the tentacles nearby along with the labels are spontaneously actuated downward, generating electrochemical responses under square wave voltammetry. Thus, it detects unamplified SARS-CoV-2 RNAs within 1 min down to 4 copies in 80 µL, 2-6 orders of magnitude lower than those of other electrochemical assays. Double-blind testing and 10-in-1 pooled testing of nasopharyngeal samples yield high overall agreement with reverse transcription-polymerase chain reaction results. We fabricate a portable prototype based on this system, showing great potential for future applications.

Computational design of ultrashort peptide inhibitors of the receptor-binding domain of the SARS-CoV-2 S protein.

Targeting the interaction between severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2)-receptor-binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2) is believed to be an effective strategy for drug design to inhibit the infection of SARS-CoV-2. Herein, several ultrashort peptidase inhibitors against the RBD-ACE2 interaction were obtained by a computer-aided approach based on the RBD-binding residues on the protease domain (PD) of ACE2. The designed peptides were tested on a model coronavirus GX_P2V, which has 92.2 and 86% amino acid identity to the SARS-CoV-2 spike protein and RBD, respectively. Molecular dynamics simulations and binding free energy analysis predicted a potential binding pocket on the RBD of the spike protein, and this was confirmed by the specifically designed peptides SI5α and SI5α-b. They have only seven residues, showing potent antiviral activity and low cytotoxicity. Enzyme-linked immunosorbent assay result also confirmed their inhibitory ability against the RBD-ACE2 interaction. The ultrashort peptides are promising precursor molecules for the drug development of Corona Virus Disease 2019, and the novel binding pocket on the RBD may be helpful for the design of RBD inhibitors or antibodies against SARS-CoV-2.

Alert for non-respiratory symptoms of coronavirus disease 2019 patients in epidemic period: A case report of familial cluster with three asymptomatic COVID-19 patients.

At present, coronavirus disease 2019 (COVID-19) is rampaging around the world. However, asymptomatic carriers intensified the difficulty of prevention and management. Here we reported the screening, clinical features, and treatment process of a family cluster involving three COVID-19 patients. The discovery of the first asymptomatic carrier in this family cluster depends on the repeated and comprehensive epidemiological investigation by disease control experts. In addition, the combination of multiple detection methods can help clinicians find asymptomatic carriers as early as possible. In conclusion, the prevention and control experience of this family cluster showed that comprehensive rigorous epidemiological investigation and combination of multiple detection methods were of great value for the detection of hidden asymptomatic carriers.

Chlorogenic acid, a natural product as potential inhibitor of COVID-19: virtual screening experiment based on network pharmacology and molecular docking.

Chlorogenic acid (CGA) is a potential inhibitor of Coronavirus Disease 2019 (COVID-19). ACE2 and its co-expressed proteins are SARS-CoV-2 receptors, which have been linked to SARS-CoV-2 infection and considered as the key target of SARS-CoV-2 in entering target cells. Here, network pharmacology was used to investigate the mechanism by which CGA affected COVID-19. A total of 70 potential targets related to the treatment of COVID-19 were obtained, among which NFE2L2, PPARG, ESR1, ACE, IL6, and HMOX1 might be the main potential targets. Finally, CGA and potential target proteins were scored by molecular docking, and the prediction results of network pharmacology were preliminarily verified. Moreover, CGA had potential anti-SARS-CoV-2 activity via integrating three common receptors in clinical practice compared with clinical trial drugs registered for the treatment of COVID-19, as shown by molecular docking. The mechanism of CGA against COVID-19 was initially investigated using network pharmacology, followed by molecular docking.

Providing targeted psychological support to frontline nurses involved in the management of COVID-19: An action research.

AIM: To develop and implement a targeted psychological support scheme for frontline nurses involved in the management of coronavirus disease 2019 (COVID-19). BACKGROUND: Nurses play a vital role in managing the ongoing COVID-19 pandemic, while confronting enormous challenges and psychological problems. METHODS: Action research design was adopted to develop and provide a targeted psychological support scheme to 1,496 frontline nurses. Data regarding nurses' feedback were collected from WeChat group chat, letters and comments on theme lectures. Subsequently, qualitative content analysis was conducted using MAXQDA. RESULTS: A targeted psychological support scheme was formed via three action cycles according to nurses' needs. Frontline nurses received psychological assistance from a research team, which offered (1) a sense of belonging, (2) a sense of professional value and pride, and (3) a sense of being protected and confident. CONCLUSION: The researchers successfully provided targeted psychological support to nurses, and nurses were motivated and became more confident when their needs were addressed. IMPLICATIONS FOR NURSING MANAGEMENT: Nurses have various types of psychological needs, which could be addressed by targeted support. It is suggested that nurse managers should identify nurses' needs in real time and provide appropriate support through multidisciplinary collaboration to improve their confidence and enhance their resilience.