Surface Spike Protein Research Articles

Distinguishing common SARS-CoV2 omicron and recombinant variants with high resolution mass spectrometry.

A selected ion monitoring (SIM) approach combined with high resolution mass spectrometry is employed to identify and distinguish common SARS-CoV2 omicron and recombinant variants in clinical specimens. Mutations within the receptor binding domain (RBD) within the surface spike protein of the virus result in a combination of peptide segments of unique sequence and mass that were monitored to detect BA.2.75 (including CH.1.1) and XBB (including 1.5) variants prevalent in the state's population in early 2023. SIM detection of pairs of peptides unique to each variant were confidently detected and differentiated in 57.3% of the specimens, with a further 10 or 17.5% (for a total of 74.8%) detected based on a single peptide biomarker. The BA.2.75 sub-variant was detected in 18.7%, while recombinant variants XBB and XBB.1.5 were detected in 13.3% and 25.3% of the specimens respectively, consistent with circulating levels in the population characterised by RT-PCR. Virus was detected in 75 SARS-CoV2 positive specimens by mass spectrometry down to the low or mid 104 copy level, with a single false positive and no false negative identified. This article is the first paper to characterise recombinant strains of the SARS-CoV2 virus by this, or any other, MS method.

Spike protein receptor-binding domains from SARS-CoV-2 variants of interest bind human ACE2 more tightly than the prototype spike protein

Several SARS-CoV-2 variants of interest (VOI) have emerged since this virus was first identified as the etiologic agent responsible for COVID-19. Some of these variants have demonstrated differences in both virulence and transmissibility, as well as in evasion of immune responses in hosts vaccinated against the original strain of SARS-CoV-2. There remains a lack of definitive evidence that identifies the genetic elements that are responsible for the differences in transmissibility among these variants. One factor affecting transmissibility is the initial binding of the surface spike protein (SP) of SARS-CoV-2 to human angiotensin converting enzyme-2 (hACE2), the widely accepted receptor for SP. This step in the viral replication process is mediated by the receptor binding domain (RBD) of SP that is located on the surface of the virus. This current study was conducted with the aim of assessing potential differences in binding affinity between recombinant hACE2 and the RBDs of emergent SARS-CoV-2 WHO VOIs. Mutations that affect the binding affinity of SP play a dominant initial role in the infectivity of the virus.

The prevalence of inverse health consequences of COVID-19 vaccines: A post-vaccination study

BackgroundCOVID-19 vaccinations are intended to help produce neutralizing antibodies which target surface spike protein to combat the SARS-Cov-2 virus. Similarly, COVID-19 recovered patients exhibit high levels of SARS-CoV-2 neutralizing antibodies, which predominantly target the surface spike protein and are associated with the occurrence of health consequences in survivors. ObjectiveThe aim of the study is to explore the long-term health consequences of the COVID-19 vaccines. MethodologyA prospective, exploratory observational study conducted both online and offline using various questionnaires with all immunized individuals who had been inoculated for at least a month following their last COVID-19 vaccine either AZD1222® or BBV152® vaccines. ResultsWe evaluated 258 individuals who had taken the COVID vaccine and found that females made up the majority (54.3%) and that the mean age was 24 years. Post-vaccination long-term health issues were reported by 36.05% (93) of the participants, with 37.86% (53) of females and 33.9% (40) of males (p = 0.292). Myalgia was reported by 20.15% (52), fatigue was 13.95% (36), paresthesia was 1.16% (3), ageusia was 0.77% (2), sadness/irritability was 2.31% (6), and lack of concentration/excessive worry was 3.1% (8). ConclusionsMyalgia, fatigue, paresthesia, ageusia, coughs and colds, dyspnea, sadness/irritability, and lack of concentration/excessive worry are health consequences related to the COVID-19 vaccination which follow a similar pattern of post-COVID syndrome.

Nanodiamond conjugated SARS-CoV-2 spike protein: electrochemical impedance immunosensing on a gold microelectrode.

A promising immunosensing strategy in diagnosing SARS-CoV-2 is proposed using a 10-µm gap-sized gold interdigitated electrode (AuIDE) to target the surface spike protein (SP). The microelectrode surface was modified by (3-glycidyloxypropyl) trimethoxysilane to enforce the epoxy matrix, which facilitates the immobilization of the anti-SP antibody. The immunosensing performance was evaluated by integrating a nanosized (~ 10 nm) diamond-complexed SP as a target. The proposed immunoassay was quantitatively evaluated through electrochemical impedance spectroscopy (EIS) with the swept frequency from 0.1 to 1 MHz using a 100 mVRMS AC voltage supply. The immunoassay performed without diamond integration showed low sensitivity, with the lowest SP concentration measured at 1 pM at a determination coefficient of R2 = 0.9681. In contrast, the nanodiamond-conjugated SP on the immunosensor showed excellent sensitivity with a determination coefficient of R2 = 0.986. SP detection with a nanodiamond-conjugated target on AuIDE reached the low limit of detection at 189 fM in a linear detection range from 250 to 8000 fM. The specificity of the developed immunosensor was evaluated by interacting influenza-hemagglutinin and SARS-CoV-2-nucleocapsid protein with anti-SP. In addition, the authentic interaction of SP and anti-SP was validated by enzyme-linked immunosorbent assay.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00604-022-05320-7.

Transient production of receptor-binding domain of SARS-CoV-2 in Nicotiana benthamiana plants induces specific antibodies in immunized mice.

BackgroundThe COVID-19 pandemic caused by the SARS-CoV-2 coronavirus has currently affected millions of people around the world. To combat the rapid spread of COVID-19 there is an urgent need to implement technological platforms for the production of vaccines, drugs and diagnostic systems by the scientific community and pharmaceutical companies. The SARS-CoV-2 virus enters the cells by the interaction between the receptor-binding domain (RBD) present in the viral surface spike protein and its human receptor ACE2. The RBD protein is therefore considered as the target for potential subunit-based vaccines.Methods and resultsWe evaluate the use of Nicotiana benthamiana plants as the host to transiently-producing recombinant RBD (RBDr) protein. The identity of the plant-produced RBDr was confirmed by immune assays and mass spectrometry. Immunogenicity was confirmed through the specific antibodies generated in all of the immunized mice compared to the PBS treated group.ConclusionsIn conclusions, the immunogenicity of the RBDr produced in N. benthamiana was confirmed. These findings support the use of plants as an antigen expression system for the rapid development of vaccine candidates.

Semi-Mechanistic Pharmacokinetic-Pharmacodynamic Model of Camostat Mesylate-Predicted Efficacy against SARS-CoV-2 in COVID-19.

ABSTRACTThe SARS-CoV-2 coronavirus, which causes COVID-19, uses a viral surface spike protein for host cell entry and the human cell-surface transmembrane serine protease, TMPRSS2, to process the spike protein. Camostat mesylate, an orally available and clinically used serine protease inhibitor, inhibits TMPRSS2, supporting clinical trials to investigate its use in COVID-19. A one-compartment pharmacokinetic (PK)/pharmacodynamic (PD) model for camostat and the active metabolite FOY-251 was developed, incorporating TMPRSS2 reversible covalent inhibition by FOY-251, and empirical equations linking TMPRSS2 inhibition of SARS-CoV-2 cell entry. The model predicts that 95% inhibition of TMPRSS2 is required for 50% inhibition of viral entry efficiency. For camostat 200 mg dosed four times daily, 90% inhibition of TMPRSS2 is predicted to occur but with only about 40% viral entry inhibition. For 3-fold higher camostat dosing, marginal improvement of viral entry rate inhibition, up to 54%, is predicted. Because respiratory tract viral load may be associated with negative outcome, even modestly reducing viral entry and respiratory tract viral load may reduce disease progression. This modeling also supports medicinal chemistry approaches to enhancing PK/PD and potency of the camostat molecule.IMPORTANCE Strategies to repurpose already-approved drugs for the treatment of COVID-19 has been attractive since the beginning of the pandemic. Camostat mesylate, a serine protease inhibitor approved in Japan for the treatment of acute exacerbations of chronic pancreatitis, inhibits TMPRSS1, a host cell surface serine protease essential for SARS-CoV-2 viral entry. In vitro experiments provided data suggesting that camostat might be effective in the treatment of COVID-19. Multiple clinical trials were planned to test the hypothesis that camostat would be beneficial for treating COVID-19 (for example, clinicaltrials.gov, NCT04353284). The present work used a one-compartment pharmacokinetic (PK)/pharmacodynamic (PD) mathematical model for camostat and the active metabolite FOY-251, incorporating TMPRSS2 reversible covalent inhibition by FOY-251, and empirical equations linking TMPRSS2 inhibition of SARS-CoV-2 cell entry. This work is valuable to guide further development of camostat mesylate and possible medicinal chemistry derivatives for the treatment of COVID-19.

The prevalence of inverse health consequences of COVID-19 vaccines: A post-vaccination study

BackgroundCOVID-19 vaccinations are intended to help produce neutralizing antibodies which target surface spike protein to combat the SARS-Cov-2 virus. Similarly, COVID-19 recovered patients exhibit high levels of SARS-CoV-2 neutralizing antibodies, which predominantly target the surface spike protein and are associated with the occurrence of health consequences in survivors. ObjectiveThe aim of the study is to explore the long-term health consequences of the COVID-19 vaccines. MethodologyA prospective, exploratory observational study conducted both online and offline using various questionnaires with all immunized individuals who had been inoculated for at least a month following their last COVID-19 vaccine either AZD1222® or BBV152® vaccines. ResultsWe evaluated 258 individuals who had taken the COVID vaccine and found that females made up the majority (54.3%) and that the mean age was 24 years. Post-vaccination long-term health issues were reported by 36.05% (93) of the participants, with 37.86% (53) of females and 33.9% (40) of males (p = 0.292). Myalgia was reported by 20.15% (52), fatigue was 13.95% (36), paresthesia was 1.16% (3), ageusia was 0.77% (2), sadness/irritability was 2.31% (6), and lack of concentration/excessive worry was 3.1% (8). ConclusionsMyalgia, fatigue, paresthesia, ageusia, coughs and colds, dyspnea, sadness/irritability, and lack of concentration/excessive worry are health consequences related to the COVID-19 vaccination which follow a similar pattern of post-COVID syndrome.

Vaccination with SARS-CoV-2 spike protein lacking glycan shields elicits enhanced protective responses in animal models.

A major challenge to end the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is to develop a broadly protective vaccine that elicits long-term immunity. As the key immunogen, the viral surface spike (S) protein is frequently mutated, and conserved epitopes are shielded by glycans. Here, we revealed that S protein glycosylation has site-differential effects on viral infectivity. We found that S protein generated by lung epithelial cells has glycoforms associated with increased infectivity. Compared to the fully glycosylated S protein, immunization of S protein with N-glycans trimmed to the mono-GlcNAc-decorated state (SMG) elicited stronger immune responses and better protection for human angiotensin-converting enzyme 2 (hACE2) transgenic mice against variants of concern (VOCs). In addition, a broadly neutralizing monoclonal antibody was identified from SMG-immunized mice that could neutralize wild-type SARS-CoV-2 and VOCs with subpicomolar potency. Together, these results demonstrate that removal of glycan shields to better expose the conserved sequences has the potential to be an effective and simple approach for developing a broadly protective SARS-CoV-2 vaccine.

Immunodominant Linear B-Cell Epitopes of SARS-CoV-2 Spike, Identified by Sera from K18-hACE2 Mice Infected with the WT or Variant Viruses.

SARS-CoV-2 surface spike protein mediates the viral entry into the host cell and represents the primary immunological target of COVID-19 vaccines as well as post-exposure immunotherapy. Establishment of the highly immunogenic B-cell epitope profile of SARS-CoV-2 proteins in general, and that of the spike protein in particular, may contribute to the development of sensitive diagnostic tools and identification of vaccine` candidate targets. In the current study, the anti-viral antibody response in transgenic K18-hACE-2 mice was examined by implementing an immunodominant epitope mapping approach of the SARS-CoV-2 spike. Serum samples for probing an epitope array covering the entire spike protein were collected from mice following infection with the original SARS-CoV-2 strain as well as the B.1.1.7 Alpha and B.1.351 Beta genetic variants of concern. The analysis resulted in distinction of six linear epitopes common to the humoral response against all virus variants inspected at a frequency of more than 20% of the serum samples. Finally, the universality of the response was probed by cross-protective in vitro experiments using plaque-reducing neutralization tests. The data presented here has important implications for prediction of the efficacy of immune countermeasures against emerging SARS-CoV-2 variants.

Coumarins and Quinolones as Effective Multiple Targeted Agents Versus Covid-19: An In Silico Study.

The Covid-19 virus emerged a few months ago in China, and infections rapidly escalated into a pandemic. To date, there is no selective antiviral agent for the management of pathologies associated with covid-19 and the need for an effective agent against it is essential. In this work, two home-made databases from synthetic quinolines and coumarins were virtually docked against viral proteases (3CL and PL), human cell surface proteases (TMPRSS2 and furin) and spike proteins (S1 and S2). Chloroquine, a reference drug without a clear mechanism against coronavirus was also docked on mentioned targets and the binding affinities compared with title compounds. The best compounds of synthetic coumarins and quinolines for each target were determined. All compounds against all targets showed binding affinity between -5.80 to -8.99 kcal/mol in comparison with the FDA-approved drug, Chloroquine, with binding affinity of -5.7 to -7.98 kcal/mol. Two compounds, quinoline-1 and coumarin-24, were found to be effective on three targets - S2, TMPRSS2 and furin - simultaneously, with good predicted affinity between -7.54 to -8.85 kcal/mol. In silico ADME studies also confirmed good oral absorption for them. Furthermore, PASS prediction was calculated and coumarin-24 had higher probable activity (Pa) than probable inactivity (Pi) with acceptable protease inhibitory as well as good antiviral activity against Hepatitis C virus (HCV), Human immunodeficiency virus (HIV) and influenza. Quinoline-1 and Coumarin-24 have the potential to be used against Covid-19. Hence these agents could be useful in combating covid-19 infection after further in vitro and in vivo studies.

Detection of SARS CoV-2 coronavirus omicron variant with mass spectrometry.

Mass mapping using high resolution mass spectrometry has been applied to identify and rapidly distinguish the omicron variant of the SARS-CoV2 coronavirus strains from other major variants of concern. Insertions, deletions and mutations within the surface spike protein result in associated mass differences in the mass maps that distinguish the variant from the originating strain and the preceding alpha, beta, gamma and delta variants of concern. The same mass map profiles can also be used to construct phylogenetic trees, without the need for protein (or gene) sequences or their alignment, in order to chart and study the origins of the variants, or any other strains. The speed and sensitivity of mass spectrometric analysis is demonstrated for a preliminary set of clinical specimens with comparable sample handling to that required in PCR based approaches.

A NEW PANEL OF MONOCLONAL ANTIBODIES TO RECOMBINANT SARS-COV-2 SPIKE ANTIGEN FOR DIAGNOSTICS

Two collections of hybridomas synthesizing antibodies to various regions of the SARS-CoV-2 surface Spike (S) protein were obtained. The candidate pairs of monoclonal antibodies were selected for constructing a kit that detects the SARS-CoV-2 S protein.

DNA aptamers inhibit SARS-CoV-2 spike-protein binding to hACE2 by an RBD- independent or dependent approach.

Objective: Nobody knows when the COVID-19 pandemic will end or when and where the next coronavirus will outbreak. Therefore, it is still necessary to develop SARS-CoV-2 inhibitors for different variants or even the new coronavirus. Since SARS-CoV-2 uses its surface spike-protein to recognize hACE2, mediating its entry into cells, ligands that can specifically recognize the spike-protein have the potential to prevent infection.Methods: We have recently discovered DNA aptamers against the S2-domain of the WT spike-protein by exploiting the selection process called SELEX. After optimization, among all candidates, the aptamer S2A2C1 has the shortest sequence and the best binding affinity toward the S2-protein. More importantly, the S2A2C1 aptamer does not bind to the RBD of the spike-protein, but it efficiently blocks the spike-protein/hACE2 interaction, suggesting an RBD-independent inhibition approach. To further improve its performance, we conjugated the S2A2C1 aptamer with a reported anti-RBD aptamer, S1B6C3, using various linkers and constructed hetero-bivalent fusion aptamers. Binding affinities of mono and fusion aptamers against the spike-proteins were measured. The inhibition efficacies of mono and fusion aptamers to prevent the hACE2/spike-protein interaction were determined using ELISA.Results: Anti-spike-protein aptamers, including S2A2C1 and S1B6C3-A5-S2A2C1, maintained high binding affinity toward the WT, Delta, and Omicron spike-proteins and high inhibition efficacies to prevent them from binding to hACE2, rendering them well-suited as diagnostic and therapeutic molecular tools to target SARS-CoV-2 and its variants.Conclusions: Overall, we discovered the anti-S2 aptamer, S2A2C1, which inhibits the hACE2/spike-protein interaction via an RBD-independent approach. The anti-S2 and anti-RBD aptamers were conjugated to obtain the fusion aptamer, S1B6C3-A5-S2A2C1, which recognizes the spike-protein by an RBD-dependent approach. Our strategies, which discovered aptamer inhibitors targeting the highly conserved S2-protein, as well as the design of fusion aptamers, can be used to target new coronaviruses as they emerge.

The Nuts and Bolts of SARS-CoV-2 Spike Receptor-Binding Domain Heterologous Expression.

COVID-19 is a highly infectious disease caused by a newly emerged coronavirus (SARS-CoV-2) that has rapidly progressed into a pandemic. This unprecedent emergency has stressed the significance of developing effective therapeutics to fight the current and future outbreaks. The receptor-binding domain (RBD) of the SARS-CoV-2 surface Spike protein is the main target for vaccines and represents a helpful “tool” to produce neutralizing antibodies or diagnostic kits. In this work, we provide a detailed characterization of the native RBD produced in three major model systems: Escherichia coli, insect and HEK-293 cells. Circular dichroism, gel filtration chromatography and thermal denaturation experiments indicated that recombinant SARS-CoV-2 RBD proteins are stable and correctly folded. In addition, their functionality and receptor-binding ability were further evaluated through ELISA, flow cytometry assays and bio-layer interferometry.

The Effect of Coronavirus Disease 2019 on Reproduction System and Fertility

As of October 9, 2020, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was recorded to have infected more than 235 countries and 36,361,054 people globally, and 1,056,186 people died from coronavirus disease 2019 (COVID-19). In early October 2020, it was reported that the rate of increase in new cases reached 300,000 cases per day. A scientific reference source about COVID-19 in pregnancy and fertility system based on the results of previous research. By conducting a literature search that was carried out until October 12, 2020, through the PubMed and Google Scholar databases using the keyword COVID-19 and pregnancy, 20 articles were used as a reference source. Human SARS-CoV appeared in China, causing a deadly epidemic 18 years ago. Novel coronavirus-2019 infects target cells by binding to angiotensin-converting enzyme 2 (ACE2) through its surface spike protein. nCoV-2 modulates ACE2 expression and causes serious injury, similar to SARS-CoV. There is the possibility that the SARS-CoV-2 mechanism can affect fertility on female, namely, SARS-CoV-2 can harm ovarian tissue and granulosa cells, and reduce ovarian function and quality of oocytes, and can make infertility or miscarriage; also damage the endometrial epithelium and affect early embryo implantation. COVID-19 is caused by SARS-CoV-2 which is an acute infectious disease that mostly affects the respiratory system, but can also attack the reproductive system.

Update: Drug treatment options for coronavirus disease 2019 (COVID-19).

Coronavirus disease 19 (COVID-19) continues to rage as a global pandemic. A number of potential therapeutic agents have been explored over the past year or two. However, numerous drugs that were expected to prove highly effective, such as lopinavir/ritonavir and remdesivir, have been found to have little benefit in large clinical trials. Interleukin-6 receptor antagonists, glucocorticoids, Janus kinase inhibitors, and some antivirals have been found to provide significant benefits in terms of reducing viral load, reducing the time of nucleic acid conversion, or improving survival. For example, bamlanivimab and etesevimab, which are newly designed monoclonal antibodies against the surface spike protein S1 subunit receptor-binding domain (RBD) of SARS-CoV-2, have a significant effect on reducing the viral load and the hospitalization rate of patients with mild COVID-19. Several vaccines against SARS-CoV-2 have been widely administered worldwide and have provided good protection. Nevertheless, the increasingly hardy variants of the virus have raised the requirements for vaccine design. Perhaps RBD-based vaccines are a viable way to defend against variants, but this still needs to be verified in a large sample. Therefore, this paper provides an update on the treatment options for COVID-19 based on three previously proposed dimensions of drug screening: standard assays of existing broad-spectrum antivirals, screening of chemical libraries, and redevelopment of new, specific drugs.

Carbon nanotube field-effect transistor (CNT-FET)-based biosensor for rapid detection of SARS-CoV-2 (COVID-19) surface spike protein S1

The large-scale diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is important for traceability and treatment during pandemic outbreaks. We developed a fast (2–3 min), easy-to-use, low-cost, and quantitative electrochemical biosensor based on carbon nanotube field-effect transistor (CNT-FET) that allows digital detection of the SARS-CoV-2 S1 in fortifited saliva samples for quick and accurate detection of SARS-CoV-2 S1 antigens. The biosensor was developed on a Si/SiO2 surface by CNT printing with the immobilization of a anti-SARS-CoV-2 S1. SARS-CoV-2 S1 antibody was immobilized on the CNT surface between the S-D channel area using a linker 1-pyrenebutanoic acid succinimidyl ester (PBASE) through non-covalent interaction. A commercial SARS-CoV-2 S1 antigen was used to characterize the electrical output of the CNT-FET biosensor. The SARS-CoV-2 S1 antigen in the 10 mM AA buffer pH 6.0 was effectively detected by the CNT-FET biosensor at concentrations from 0.1 fg/mL to 5.0 pg/mL. The limit of detection (LOD) of the developed CNT-FET biosensor was 4.12 fg/mL. The selectivity test was performed by using target SARS-CoV-2 S1 and non-target SARS-CoV-1 S1 and MERS-CoV S1 antigens in the 10 mM AA buffer pH 6.0. The biosensor showed high selectivity (no response to SARS-CoV-1 S1 or MERS-CoV S1 antigen) with SARS-CoV-2 S1 antigen detection in the 10 mM AA buffer pH 6.0. The biosensor is highly sensitive, saves time, and could be a helpful platform for rapid detection of SARS-CoV-2 S1 antigen from the patients saliva.

Recent Update of COVID-19 Vaccines.

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) has been recently identified as a novel member of beta coronaviruses (CoVs) and the cause of coronavirus disease 2019 (COVID-19). It has been first discovered in China and soon has spread across continents with an escalating number of mortalities. There is an urgent need for developing a COVID-19 vaccine to control the rapid transmission and the deleterious impact of the virus. The potent vaccine should have a good tolerable and efficacious profile to induce target-specific humoral and cellular immune responses. It should also exhibit no or minimal detrimental effects in children, young adults, and elderly people with or without co-morbidities from different racial backgrounds. Previously published findings of SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV) played vital role in the characterization of surface spike proteins as the tool of entry of the SARS-CoV-2 into host cells. It has become evident that SARS-CoVs have high genetic similarity and this implies antecedent vaccination strategies could be implicated in the production of COVID-19 vaccines. Although several vaccines have been approved and rolled out, only a handful of them have passed the three phases of clinical studies. This review highlights the completed, and ongoing clinical trials of COVID-19 vaccines and efforts are being made globally to avert the pandemic.

Genetic drift in the genome of SARS COV-2 and its global health concern.

The outbreak of the current coronavirus disease (COVID‐19) occurred in late 2019 and quickly spread all over the world. The severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) belongs to a genetically diverse group that mutates continuously leading to the emergence of multiple variants. Although a few antiviral agents and anti‐inflammatory medicines are available, thousands of individuals have passed away due to emergence of new viral variants. Thus, proper surveillance of the SARS‐CoV‐2 genome is needed for the rapid identification of developing mutations over time, which are of the major concern if they occur specifically in the surface spike proteins of the virus (neutralizing analyte). This article reviews the potential mutations acquired by the SARS‐CoV2 since the pandemic began and their significant impact on the neutralizing efficiency of vaccines and validity of the diagnostic assays.

Neutralization of SARS-CoV-2 requires antibodies against conformational receptor-binding domain epitopes.

BackgroundThe determinants of successful humoral immune response to the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) are of critical importance for the design of effective vaccines and the evaluation of the degree of protective immunity conferred by exposure to the virus. As novel variants emerge, understanding their likelihood of suppression by population antibody repertoires has become increasingly important.MethodsIn this study, we analyzed the SARS‐CoV‐2 polyclonal antibody response in a large population of clinically well‐characterized patients after mild and severe COVID‐19 using a panel of microarrayed structurally folded and unfolded SARS‐CoV‐2 proteins, as well as sequential peptides, spanning the surface spike protein (S) and the receptor‐binding domain (RBD) of the virus.ResultsS‐ and RBD‐specific antibody responses were dominated by immunoglobulin G (IgG), mainly IgG1, and directed against structurally folded S and RBD and three distinct peptide epitopes in S2. The virus neutralization activity of patients´ sera was highly correlated with IgG antibodies specific for conformational but not sequential RBD epitopes and their ability to prevent RBD binding to its human receptor angiotensin‐converting enzyme 2 (ACE2). Twenty percent of patients selectively lacked RBD‐specific IgG. Only immunization with folded, but not with unfolded RBD, induced antibodies against conformational epitopes with high virus‐neutralizing activity. Conformational RBD epitopes required for protection do not seem to be altered in the currently emerging virus variants.ConclusionThese results are fundamental for estimating the protective activity of antibody responses after natural infection or vaccination and for the design of vaccines, which can induce high levels of SARS‐CoV‐2–neutralizing antibodies conferring sterilizing immunity.