Cryoelectron microscopy structures of a human neutralizing antibody bound to MERS-CoV spike glycoprotein.

Neutralizing monoclonal antibodies (mAbs) against highly pathogenic coronaviruses represent promising candidates for clinical intervention. Here, we isolated a potent neutralizing monoclonal antibody, MERS-S41, from a yeast displayed scFv library using the S protein as a bait. To uncover the neutralization mechanism, we determined structures of MERS-S41 Fab in complex with the trimeric spike glycoprotein by cryoelectron microscopy (cryo-EM). We observed four distinct classes of the complex structure, which showed that the MERS-S41 Fab bound to the "up" receptor binding domain (RBD) with full saturation and also bound to an accessible partially lifted "down" RBD, providing a structural basis for understanding how mAbs bind to trimeric spike glycoproteins. Structure analysis of the epitope and cell surface staining assays demonstrated that virus entry is blocked predominantly by direct competition with the host receptor, dipeptidyl peptidase-4 (DPP4).

Cryoelectron microscopy structures of a human neutralizing antibody bound to MERS-CoV spike glycoprotein

Neutralizing monoclonal antibodies (mAbs) against highly pathogenic coronaviruses represent promising candidates for clinical intervention. Here, we isolated a potent neutralizing monoclonal antibody, MERS-S41, from a yeast displayed scFv library using the S protein as a bait. To uncover the neutralization mechanism, we determined structures of MERS-S41 Fab in complex with the trimeric spike glycoprotein by cryoelectron microscopy (cryo-EM). We observed four distinct classes of the complex structure, which showed that the MERS-S41 Fab bound to the “up” receptor binding domain (RBD) with full saturation and also bound to an accessible partially lifted “down” RBD, providing a structural basis for understanding how mAbs bind to trimeric spike glycoproteins. Structure analysis of the epitope and cell surface staining assays demonstrated that virus entry is blocked predominantly by direct competition with the host receptor, dipeptidyl peptidase-4 (DPP4).

The spike glycoprotein of highly pathogenic human coronaviruses: structural insights for understanding infection, evolution and inhibition.

Highly pathogenic human coronaviruses (CoV) including SARS-CoV, MERS-CoV and SARS-CoV-2 have emerged over the past two decades, resulting in infectious disease outbreaks that have greatly affected public health. The CoV surface spike (S) glycoprotein mediates receptor binding and membrane fusion for cell entry, playing critical roles in CoV infection and evolution. The S glycoprotein is also the major target molecule for prophylactic and therapeutic interventions, including neutralizing antibodies and vaccines. In this review, we summarize key studies that have revealed the structural basis of S-mediated cell entry of SARS-CoV, MERS-CoV and SARS-CoV-2. Additionally, we discuss the evolution of the S glycoprotein to realize cross-species transmission from the viewpoint of structural biology. Lastly, we describe the recent progress in developing antibodies, nanobodies and peptide inhibitors that target the SARS-CoV-2 S glycoprotein for therapeutic purposes.

RBD trimer mRNA vaccine elicits broad and protective immune responses against SARS-CoV-2 variants.

With the rapid emergence and spread of SARS-CoV-2 variants, development of vaccines with broad and potent protectivity has become a global priority. Here, we designed a lipid nanoparticle-encapsulated, nucleoside-unmodified mRNA (mRNA-LNP) vaccine encoding the trimerized receptor-binding domain (RBD trimer) and showed its robust capability in inducing broad and protective immune responses against wild-type and major variants of concern (VOCs) in the mouse model of SARS-CoV-2 infection. The protectivity was correlated with RBD-specific B cell responses especially the long-lived plasma B cells in bone marrow, strong ability in triggering BCR clustering, and downstream signaling. Monoclonal antibodies isolated from vaccinated animals demonstrated broad and potent neutralizing activity against VOCs tested. Structure analysis of one representative antibody identified a novel epitope with a high degree of conservation among different variants. Collectively, these results demonstrate that the RBD trimer mRNA vaccine serves as a promising vaccine candidate against SARS-CoV-2 variants and beyond.

Anxiety, home blood pressure monitoring, and cardiovascular events among older hypertension patients during the COVID-19 pandemic.

The global coronavirus disease 2019 (COVID-19) pandemic has led to a health crisis. It remains unclear how anxiety affects blood pressure (BP) and cardiovascular risk among older patients with hypertension. In this study, we extracted longitudinal data on home BP monitored via a smartphone-based application in 3724 elderly patients with hypertension from a clinical trial (60-80 years; 240 in Wuhan and 3484 in non-Wuhan areas) to examine changes in morning BP during the COVID-19 outbreak in China. Anxiety was evaluated using Generalized Anxiety Disorder-7 item scores. Changes in morning systolic BP (SBP) were analyzed for five 30-day periods during the pandemic (October 21, 2019 to March 21, 2020), including the pre-epidemic, incubation, developing, outbreak, and plateau periods. Data on cardiovascular events were prospectively collected for one year. A total of 262 individuals (7.0%) reported an increased level of anxiety, and 3462 individuals (93.0%) did not. Patients with anxiety showed higher morning SBP than patients without anxiety, and the between-group differences in SBP change were +1.2 mmHg and +1.7 mmHg during the outbreak and plateau periods (P < 0.05), respectively. The seasonal BP variation in winter among patients with anxiety was suppressed during the pandemic. Anxious patients had higher rates of uncontrolled BP. During the 1-year follow-up period, patients with anxiety had an increased risk of cardiovascular events with a hazard ratio of 2.47 (95% confidence interval, 1.10-5.58; P = 0.03). In summary, COVID-19-related anxiety was associated with a short-term increase in morning SBP among older patients and led to a greater risk of cardiovascular events. (ClinicalTrials. gov number, NCT03015311).

A Potent and Protective Human Neutralizing Antibody Against SARS-CoV-2 Variants.

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to emerge and spread around the world, antibodies and vaccines to confer broad and potent neutralizing activity are urgently needed. Through the isolation and characterization of monoclonal antibodies (mAbs) from individuals infected with SARS-CoV-2, we identified one antibody, P36-5D2, capable of neutralizing the major SARS-CoV-2 variants of concern. Crystal and electron cryo-microscopy (cryo-EM) structure analyses revealed that P36-5D2 targeted to a conserved epitope on the receptor-binding domain of the spike protein, withstanding the three key mutations-K417N, E484K, and N501Y-found in the variants that are responsible for escape from many potent neutralizing mAbs, including some already approved for emergency use authorization (EUA). A single intraperitoneal (IP) injection of P36-5D2 as a prophylactic treatment completely protected animals from challenge of infectious SARS-CoV-2 Alpha and Beta. Treated animals manifested normal body weight and were devoid of infection-associated death up to 14 days. A substantial decrease of the infectious virus in the lungs and brain, as well as reduced lung pathology, was found in these animals compared to the controls. Thus, P36-5D2 represents a new and desirable human antibody against the current and emerging SARS-CoV-2 variants.

Changes in Home Blood Pressure Monitored Among Elderly Patients With Hypertension During the COVID-19 Outbreak: A Longitudinal Study in China Leveraging a Smartphone-Based Application.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has impacted clinical care worldwide. Evidence of how this health crisis affected common conditions like blood pressure (BP) control is uncertain. METHODS: We used longitudinal BP data from an ongoing randomized clinical trial to examine variations in home BP monitored via a smartphone-based application (app) in a total of 7394 elderly patients with hypertension aged 60 to 80 years stratified by their location in Wuhan (n=283) compared with other provinces of China (n=7111). Change in morning systolic BP (SBP) was analyzed for 5 30-day phases during the pandemic, including preepidemic (October 21 to November 20, 2019), incubation (November 21 to December 20, 2019), developing (December 21, 2019 to January 20, 2020), outbreak (January 21 to February 20, 2020), and plateau (February 21 to March 21, 2020). RESULTS: Compared with non-Wuhan areas of China, average morning SBP (adjusted for age, sex, body mass index) in Wuhan patients was significantly higher during the epidemic growth phases, which returned to normal at the plateau. Between-group differences in ΔSBP were +2.5, +3.0, and +2.1 mm Hg at the incubation, developing, and outbreak phases of COVID-19 (P<0.001), respectively. Sensitivity analysis showed a similar trend in trajectory pattern of SBP in both the intensive and standard BP control groups of the trial. Patients in Wuhan also had an increased regimen change in antihypertensive drugs during the outbreak compared with non-Wuhan patients. Expectedly, Wuhan patients were more likely to check their BP via the app, while doctors were less likely to monitor the app for BP control during the pandemic. CONCLUSIONS: Our data demonstrate that the COVID-19 pandemic was associated with a short-term increase in morning SBP among elderly patients with hypertension in Wuhan but not other parts of China. Further study will be needed to understand if these findings extended to other parts of the world substantially affected by the virus. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03015311.

Structural basis for bivalent binding and inhibition of SARS-CoV-2 infection by human potent neutralizing antibodies.

Neutralizing monoclonal antibodies (nAbs) to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) represent promising candidates for clinical intervention against coronavirus disease 2019 (COVID-19). We isolated a large number of nAbs from SARS-CoV-2-infected individuals capable of disrupting proper interaction between the receptor binding domain (RBD) of the viral spike (S) protein and the receptor angiotensin converting enzyme 2 (ACE2). However, the structural basis for their potent neutralizing activity remains unclear. Here, we report cryo-EM structures of the ten most potent nAbs in their native full-length IgG-form or in both IgG-form and Fab-form bound to the trimeric S protein of SARS-CoV-2. The bivalent binding of the full-length IgG is found to associate with more RBDs in the "up" conformation than the monovalent binding of Fab, perhaps contributing to the enhanced neutralizing activity of IgG and triggering more shedding of the S1 subunit from the S protein. Comparison of a large number of nAbs identified common and unique structural features associated with their potent neutralizing activities. This work provides a structural basis for further understanding the mechanism of nAbs, especially through revealing the bivalent binding and its correlation with more potent neutralization and the shedding of S1 subunit.

Bat and pangolin coronavirus spike glycoprotein structures provide insights into SARS-CoV-2 evolution.

In recognizing the host cellular receptor and mediating fusion of virus and cell membranes, the spike (S) glycoprotein of coronaviruses is the most critical viral protein for cross-species transmission and infection. Here we determined the cryo-EM structures of the spikes from bat (RaTG13) and pangolin (PCoV_GX) coronaviruses, which are closely related to SARS-CoV-2. All three receptor-binding domains (RBDs) of these two spike trimers are in the "down" conformation, indicating they are more prone to adopt the receptor-binding inactive state. However, we found that the PCoV_GX, but not the RaTG13, spike is comparable to the SARS-CoV-2 spike in binding the human ACE2 receptor and supporting pseudovirus cell entry. We further identified critical residues in the RBD underlying different activities of the RaTG13 and PCoV_GX/SARS-CoV-2 spikes. These results collectively indicate that tight RBD-ACE2 binding and efficient RBD conformational sampling are required for the evolution of SARS-CoV-2 to gain highly efficient infection.

Complete and enduring response in an elderly patient with repeated recurrent gingival squamous cell carcinoma treated by combined toripalimab and single agent chemotherapy: a case report.

Combined immune checkpoint inhibitor with platinum-based doublet chemotherapy brought about significant improvement in overall survival as the first line treatment in metastatic and recurrent head and neck cancer patients. However, in elderly patients with relatively poor performance status, these regimens might not be well tolerated. Therefore, we evaluated the safety and effect of combined immunotherapy and single agent chemotherapy in an elderly patient with recurrent head and neck squamous cell carcinoma. A 78-year-old male patients with a repeatedly recurrent gingival squamous cell carcinoma was admitted in our institute. Previously this patient underwent two consecutive surgical resections of recurrent tumors before the second rapid recurrence that resulted in extended tumor mass and lymph node metastasis. As the patient was in a relatively poor performance status (performance status =2), immunotherapy with PD-1 antibody (Toripalimab) combined with single agent chemotherapy (two cycle with albumin-bound paclitaxel and then six cycles with gemcitabine) was administrated, which led to clinical complete response after 8 cycles of treatment. The patient continued 4 cycles of maintenance immunotherapy with Toripalimab until the outbreak of the coronavirus disease 2019. The treatment was well tolerated and the patient remained free from disease until the last follow up by June 2020, 16 months after the initiation of treatment. The success in this case indicated that the combination of anti-PD-1 antibody and single chemotherapy agent may also be effective as well as safe in elderly patients with recurrent head and neck squamous cell carcinoma.