The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection is not limited to the respiratory tract as receptors, including the angiotensin-converting enzyme 2 (ACE2), are expressed across many tissues. This study employed a new conditional mouse model, Rosa26creERT2/chACE2, which expresses human ACE2 (hACE2) across multiple organs, to investigate the effects of SARS-CoV-2 infection beyond the respiratory system. This strain demonstrated susceptibility to SARS-CoV-2 infection in a dose and sex-dependent manner, showing that infected male mice exhibited more severe disease outcomes, including significant weight loss, pronounced lung pathology and dysfunction, and increased mortality, compared to females. In contrast to intratracheal infection, intranasal virus administration facilitated viral spread to the brain, thereby underscoring the nasal route's role in the pathogenesis of neurological manifestations. Intranasal infection also led to increased innate immune system activation as compared to intratracheal virus administration, even though both routes activated the adaptive immune response. This model provides a valuable tool to study SARS-CoV-2 in individual tissues or use a multisystemic approach, and it also advances possibilities for preclinical evaluation of antiviral therapies and vaccine strategies.

• Keywords
• Conditional mouse model, Infection, SARS-CoV-2, hACE2,
• MeSH
• Angiotensin-Converting Enzyme 2 * genetics   metabolism   MeSH
• COVID-19 * pathology   virology   immunology   genetics   MeSH
• Respiratory System virology   pathology   MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Mice, Transgenic MeSH
• Mice MeSH
• Lung virology   pathology   MeSH
• Immunity, Innate MeSH
• SARS-CoV-2 * pathogenicity   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Mice MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ACE2 protein, human MeSH Browser
• Angiotensin-Converting Enzyme 2 * MeSH

Diagnosis of SARS-CoV-2 virus is mainly based on direct detection. Determination of specific antibodies has been used mostly for epidemiological reasons. However, select immunoassays showed good correlation to plaque reduction virus neutralization test (PRNT) in smaller patient cohorts, which suggests their potential as predictors of virus neutralization titer. A total of 3,699 samples from Covid-19 patients were included in the multicentric study performed in the Czech Republic. Anti-SARS-CoV-2 antibody levels were evaluated by 8 commercial antibody assays. Simultaneously, PRNT evaluations were performed with the SARS-CoV-2 B.1.258 variant. All immunoassays showed an overall high true positive diagnostic value ranging from 79.17 to 98.04%. Several commercial EIA methods showed highly positive correlation between the assay results and PRNT levels, e.g., Liaison CoV-2 TrimericS IgG DiaSorin (Spearman r = 0.8833; Architect SASRS-CoV-2 IgG Abbott (r = 0.7298); NovaLisa SARS-CoV-2 IgG NovaTec (r = 0.7103) and Anti-SARS-CoV-2 ELISA IgG Euroimmun (r = 0.7094). While this correlation was less positive for other assays, those, conversely, presented higher true positive values. For most immunoassays, the positive percent agreement of the results was ≥ 95% in sera exhibiting PRNT levels of 1:80 and higher. The assays tested have shown variable correlation to PRNT. Those possessing high positive predictive values serve well as qualitative tests, while others can be utilised as quantitative tests highly predictive of neutralization antibody levels.

• MeSH
• COVID-19 * diagnosis   MeSH
• Immunoglobulin G MeSH
• Humans MeSH
• Neutralization Tests methods   MeSH
• Antibodies, Neutralizing MeSH
• Antibodies, Viral MeSH
• SARS-CoV-2 * MeSH
• Sensitivity and Specificity MeSH
• Serologic Tests methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Immunoglobulin G MeSH
• Antibodies, Neutralizing MeSH
• Antibodies, Viral MeSH

Emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants diminishes the efficacy of vaccines and antiviral monoclonal antibodies. Continued development of immunotherapies and vaccine immunogens resilient to viral evolution is therefore necessary. Using coldspot-guided antibody discovery, a screening approach that focuses on portions of the virus spike glycoprotein that are both functionally relevant and averse to change, we identified human neutralizing antibodies to highly conserved viral epitopes. Antibody fp.006 binds the fusion peptide and cross-reacts against coronaviruses of the four genera, including the nine human coronaviruses, through recognition of a conserved motif that includes the S2' site of proteolytic cleavage. Antibody hr2.016 targets the stem helix and neutralizes SARS-CoV-2 variants. Antibody sd1.040 binds to subdomain 1, synergizes with antibody rbd.042 for neutralization, and, similar to fp.006 and hr2.016, protects mice expressing human angiotensin-converting enzyme 2 against infection when present as a bispecific antibody. Thus, coldspot-guided antibody discovery reveals donor-derived neutralizing antibodies that are cross-reactive with Orthocoronavirinae, including SARS-CoV-2 variants.

• MeSH
• COVID-19 * MeSH
• Epitopes MeSH
• Spike Glycoprotein, Coronavirus MeSH
• Humans MeSH
• Mice MeSH
• Neutralization Tests MeSH
• Antibodies, Neutralizing * MeSH
• Antibodies, Viral MeSH
• SARS-CoV-2 MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH
• Names of Substances
• Epitopes MeSH
• Spike Glycoprotein, Coronavirus MeSH
• Antibodies, Neutralizing * MeSH
• Antibodies, Viral MeSH
• spike protein, SARS-CoV-2 MeSH Browser

UNLABELLED: Emergence of SARS-CoV-2 variants diminishes the efficacy of vaccines and antiviral monoclonal antibodies. Continued development of immunotherapies and vaccine immunogens resilient to viral evolution is therefore necessary. Using coldspot-guided antibody discovery, a screening approach that focuses on portions of the virus spike that are both functionally relevant and averse to change, we identified human neutralizing antibodies to highly conserved viral epitopes. Antibody fp.006 binds the fusion peptide and cross-reacts against coronaviruses of the four genera , including the nine human coronaviruses, through recognition of a conserved motif that includes the S2' site of proteolytic cleavage. Antibody hr2.016 targets the stem helix and neutralizes SARS-CoV-2 variants. Antibody sd1.040 binds to subdomain 1, synergizes with antibody rbd.042 for neutralization and, like fp.006 and hr2.016, protects mice when present as bispecific antibody. Thus, coldspot-guided antibody discovery reveals donor-derived neutralizing antibodies that are cross-reactive with Orthocoronavirinae , including SARS-CoV-2 variants. ONE SENTENCE SUMMARY: Broadly cross-reactive antibodies that protect from SARS-CoV-2 variants are revealed by virus coldspot-driven discovery.

• Publication type
• Journal Article MeSH
• Preprint MeSH

The Czech Republic, a part of the former Czechoslovakia, has been at the forefront of several research directions in virology, genetics and physiology [...].

• MeSH
• Virology * MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH
• Editorial MeSH
• Geographicals
• Czech Republic MeSH

BACKGROUND: The emergence of new SARS-CoV-2 variants of concern B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.617.2 (Delta) that harbor mutations in the viral S protein raised concern about activity of current vaccines and therapeutic antibodies. Independent studies have shown that mutant variants are partially or completely resistant against some of the therapeutic antibodies authorized for emergency use. METHODS: We employed hybridoma technology, ELISA-based and cell-based S-ACE2 interaction assays combined with authentic virus neutralization assays to develop second-generation antibodies, which were specifically selected for their ability to neutralize the new variants of SARS-CoV-2. FINDINGS: AX290 and AX677, two monoclonal antibodies with non-overlapping epitopes, exhibit subnanomolar or nanomolar affinities to the receptor binding domain of the viral Spike protein carrying amino acid substitutions N501Y, N439K, E484K, K417N, and a combination N501Y/E484K/K417N found in the circulating virus variants. The antibodies showed excellent neutralization of an authentic SARS-CoV-2 virus representing strains circulating in Europe in spring 2020 and also the variants of concern B.1.1.7 (Alpha), B.1.351 (Beta) and B.1.617.2 (Delta). In addition, AX677 is able to bind Omicron Spike protein just like the wild type Spike. The combination of the two antibodies prevented the appearance of escape mutations of the authentic SARS-CoV-2 virus. Prophylactic administration of AX290 and AX677, either individually or in combination, effectively reduced viral burden and inflammation in the lungs, and prevented disease in a mouse model of SARS-CoV-2 infection. INTERPRETATION: The virus-neutralizing properties were fully reproduced in chimeric mouse-human versions of the antibodies, which may represent a promising tool for COVID-19 therapy. FUNDING: The study was funded by AXON Neuroscience SE and AXON COVIDAX a.s.

• Keywords
• COVID-19, Escape mutation, Neutralizing antibodies, SARS-CoV-2, Variants of concern,
• MeSH
• Angiotensin-Converting Enzyme 2 chemistry   genetics   metabolism   MeSH
• Antigenic Drift and Shift MeSH
• COVID-19 virology   MeSH
• COVID-19 Drug Treatment MeSH
• Spike Glycoprotein, Coronavirus genetics   immunology   metabolism   MeSH
• Immunodominant Epitopes immunology   MeSH
• Kinetics MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Antibodies, Monoclonal immunology   therapeutic use   MeSH
• Mutation MeSH
• Mice MeSH
• Neutralization Tests MeSH
• Lung pathology   MeSH
• Antineoplastic Agents, Immunological immunology   therapeutic use   MeSH
• SARS-CoV-2 genetics   immunology   isolation & purification   MeSH
• Protein Binding MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• ACE2 protein, human MeSH Browser
• Angiotensin-Converting Enzyme 2 MeSH
• Spike Glycoprotein, Coronavirus MeSH
• Immunodominant Epitopes MeSH
• Antibodies, Monoclonal MeSH
• Antineoplastic Agents, Immunological MeSH
• spike protein, SARS-CoV-2 MeSH Browser