Cell Receptor ACE2 Research Articles

Ensemble-Based Mutational Profiling and Network Analysis of the SARS-CoV-2 Spike Omicron XBB Lineages for Interactions with the ACE2 Receptor and Antibodies: Cooperation of Binding Hotspots in Mediating Epistatic Couplings Underlies Binding Mechanism and Immune Escape.

In this study, we performed a computational study of binding mechanisms for the SARS-CoV-2 spike Omicron XBB lineages with the host cell receptor ACE2 and a panel of diverse class one antibodies. The central objective of this investigation was to examine the molecular factors underlying epistatic couplings among convergent evolution hotspots that enable optimal balancing of ACE2 binding and antibody evasion for Omicron variants BA.1, BA2, BA.3, BA.4/BA.5, BQ.1.1, XBB.1, XBB.1.5, and XBB.1.5 + L455F/F456L. By combining evolutionary analysis, molecular dynamics simulations, and ensemble-based mutational scanning of spike protein residues in complexes with ACE2, we identified structural stability and binding affinity hotspots that are consistent with the results of biochemical studies. In agreement with the results of deep mutational scanning experiments, our quantitative analysis correctly reproduced strong and variant-specific epistatic effects in the XBB.1.5 and BA.2 variants. It was shown that Y453W and F456L mutations can enhance ACE2 binding when coupled with Q493 in XBB.1.5, while these mutations become destabilized when coupled with the R493 position in the BA.2 variant. The results provided a molecular rationale of the epistatic mechanism in Omicron variants, showing a central role of the Q493/R493 hotspot in modulating epistatic couplings between convergent mutational sites L455F and F456L in XBB lineages. The results of mutational scanning and binding analysis of the Omicron XBB spike variants with ACE2 receptors and a panel of class one antibodies provide a quantitative rationale for the experimental evidence that epistatic interactions of the physically proximal binding hotspots Y501, R498, Q493, L455F, and F456L can determine strong ACE2 binding, while convergent mutational sites F456L and F486P are instrumental in mediating broad antibody resistance. The study supports a mechanism in which the impact on ACE2 binding affinity is mediated through a small group of universal binding hotspots, while the effect of immune evasion could be more variant-dependent and modulated by convergent mutational sites in the conformationally adaptable spike regions.

The antiviral potential of the antiandrogen enzalutamide and the viral-androgen signaling interplay in seasonal coronaviruses.

The sex disparity in COVID-19 outcomes with males generally faring worse than females has been associated with the androgen-regulated expression of the protease TMPRSS2 and the cell receptor ACE2 in the lung and fueled interest in antiandrogens as potential antivirals. In this study, we explored enzalutamide, an antiandrogen used commonly to treat prostate cancer, as a potential antiviral against the human coronaviruses which cause seasonal respiratory infections (HCoV-NL63, -229E, and -OC43). Using lentivirus-pseudotyped and authentic HCoV, we report that enzalutamide reduced 229E and NL63 entry and infection in both TMPRSS2- and nonexpressing immortalized cells, suggesting a TMPRSS2-independent mechanism. However, no effect was observed against OC43. To decipher this distinction, we performed RNA-sequencing analysis on 229E- and OC43-infected primary human airway cells. Our results show a significant induction of androgen-responsive genes by 229E compared to OC43 at 24and 72 h postinfection. The virus-mediated effect on AR-signaling was further confirmed with a consensus androgen response element-driven luciferase assay in androgen-depleted MRC-5 cells. Specifically, 229E induced luciferase-reporter activity in the presence and absence of the synthetic androgen mibolerone, while OC43 inhibited induction. These findings highlight a complex interplay between viral infections and androgen-signaling, offering insights for disparities in viral outcomes and antiviral interventions.

Susceptibility and Resistance of SARS-CoV-2 Variants to LCB1 and Its Multivalent Derivatives.

LCB1 is a computationally designed three-helix miniprotein that precisely targets the spike (S) receptor-binding motif (RBM) of SARS-CoV-2, exhibiting remarkable antiviral efficacy; however, emerging SARS-CoV-2 variants could substantially compromise its neutralization effectiveness. In this study, we constructed two multivalent LCB1 fusion proteins termed LCB1T and LCB1T-Fc, and characterized their potency in inhibiting SARS-CoV-2 pseudovirus and authentic virus in vitro. In the inhibition of various SARS-CoV-2 variants, the two LCB1 fusion proteins exhibited markedly improved inhibitory activities compared to LCB1 as anticipated; however, it was observed that relative to the D614G mutation hosting variant, the variants Delta, Lambda, and Omicron BQ.1.1, XBB, XBB.1.5, and EG.5.1 caused various degrees of resistance to the two fusion proteins' inhibition, with XBB, XBB.1.5, and EG.5.1 variants showing high-level resistance. Moreover, we demonstrated that bat coronavirus RaTG13 and pangolin coronavirus PCoV-GD/PCoV-GX were highly sensitive to two LCB1 fusion proteins, but not LCB1, inhibition. Importantly, our findings revealed a notable decrease in the blocking capacity of the multivalent LCB1 inhibitor on the interaction between the virus's RBD/S and the cell receptor ACE2 when confronted with the XBB variant compared to WT and the Omicron BA.1 variant. In conclusion, our studies provide valuable insights into the antiviral profiling of multivalent LCB1 inhibitors and offer a promising avenue for the development of novel broad-spectrum antiviral therapeutics.

Distinctive Features of the XBB.1.5 and XBB.1.16 Spike Protein Receptor-Binding Domains and Their Roles in Conformational Changes and Angiotensin-Converting Enzyme 2 Binding.

The emergence and the high transmissibility of the XBB.1.5 and XBB.1.16 subvariants of the SARS-CoV-2 omicron has reignited concerns over the potential impact on vaccine efficacy for these and future variants. We investigated the roles of the XBB.1.5 and XBB.1.16 mutations on the structure of the spike protein's receptor-binding domain (RBD) and its interactions with the host cell receptor ACE2. To bind to ACE2, the RBD must transition from the closed-form to the open-form configuration. We found that the XBB variants have less stable closed-form structures that may make the transition to the open-form easier. We found that the mutations enhance the RBD-ACE2 interactions in XBB.1.16 compared to XBB.1.5. We observed significant structural changes in the loop and motif regions of the RBD, altering well-known antibody-binding sites and potentially rendering primary RBD-specific antibodies ineffective. Our findings elucidate how subtle structural changes and interactions contribute to the subvariants' fitness over their predecessors.

Improving Soluble Expression of SARS-CoV-2 Spike Priming Protease TMPRSS2 with an Artificial Fusing Protein.

SARS-CoV-2 relies on the recognition of the spike protein by the host cell receptor ACE2 for cellular entry. In this process, transmembrane serine protease 2 (TMPRSS2) plays a pivotal role, as it acts as the principal priming agent catalyzing spike protein cleavage to initiate the fusion of the cell membrane with the virus. Thus, TMPRSS2 is an ideal pharmacological target for COVID-19 therapy development, and the effective production of high-quality TMPRSS2 protein is essential for basic and pharmacological research. Unfortunately, as a mammalian-originated protein, TMPRSS2 could not be solubly expressed in the prokaryotic system. In this study, we applied different protein engineering methods and found that an artificial protein XXA derived from an antifreeze protein can effectively promote the proper folding of TMPRSS2, leading to a significant improvement in the yield of its soluble form. Our study also showed that the fused XXA protein did not influence the enzymatic catalytic activity; instead, it greatly enhanced TMPRSS2's thermostability. Therefore, our strategy for increasing TMPRSS2 expression would be beneficial for the large-scale production of this stable enzyme, which would accelerate aniti-SARS-CoV-2 therapeutics development.

Understanding Mutations in Human SARS-CoV-2 Spike Glycoprotein: A Systematic Review & Meta-Analysis.

Genetic variant(s) of concern (VoC) of SARS-CoV-2 have been emerging worldwide due to mutations in the gene encoding spike glycoprotein. We performed comprehensive analyses of spike protein mutations in the significant variant clade of SARS-CoV-2, using the data available on the Nextstrain server. We selected various mutations, namely, A222V, N439K, N501Y, L452R, Y453F, E484K, K417N, T478K, L981F, L212I, N856K, T547K, G496S, and Y369C for this study. These mutations were chosen based on their global entropic score, emergence, spread, transmission, and their location in the spike receptor binding domain (RBD). The relative abundance of these mutations was mapped with global mutation D614G as a reference. Our analyses suggest the rapid emergence of newer global mutations alongside D614G, as reported during the recent waves of COVID-19 in various parts of the world. These mutations could be instrumentally imperative for the transmission, infectivity, virulence, and host immune system's evasion of SARS-CoV-2. The probable impact of these mutations on vaccine effectiveness, antigenic diversity, antibody interactions, protein stability, RBD flexibility, and accessibility to human cell receptor ACE2 was studied in silico. Overall, the present study can help researchers to design the next generation of vaccines and biotherapeutics to combat COVID-19 infection.

SARS-CoV-2 spike and ACE2 entanglement-like binding.

We describe the binding between the glycoprotein Spike of SARS-CoV-2 and the human host cell receptor ACE2 as a quantum circuit, comprising the one-qubit Hadamard quantum logic gate performing the quantum superposition of the S1 subunit of the Spike protein, and the two-qubit quantum logic gate CNOT, which performs maximum entanglement between the Spike-qubit S1 and the ACE2 receptor protein. Also, we consider two strategies to prevent the binding process between the Spike-qubit S1 and the ACE2 receptor. The first one is the use of competitive peptidomimetic inhibitors that can selectively bind to the receptor binding domain (RBD) of the Spike glycoprotein with much higher affinity than the cell surface receptor itself. These inhibitors are targeted to the CNOT quantum logic gate and will get maximally entangled with the S1 qubit in place of the natural ACE2 receptor. The second one is to use covalent inhibitors, which will destroy S1 by acting as a projective quantum measurement. Finally, the conjecture that S1 is a quantum bio-robot is formulated.

Force-tuned avidity of spike variant-ACE2 interactions viewed on the single-molecule level

Recent waves of COVID-19 correlate with the emergence of the Delta and the Omicron variant. We report that the Spike trimer acts as a highly dynamic molecular caliper, thereby forming up to three tight bonds through its RBDs with ACE2 expressed on the cell surface. The Spike of both Delta and Omicron (B.1.1.529) Variant enhance and markedly prolong viral attachment to the host cell receptor ACE2, as opposed to the early Wuhan-1 isolate. Delta Spike shows rapid binding of all three Spike RBDs to three different ACE2 molecules with considerably increased bond lifetime when compared to the reference strain, thereby significantly amplifying avidity. Intriguingly, Omicron (B.1.1.529) Spike displays less multivalent bindings to ACE2 molecules, yet with a ten time longer bond lifetime than Delta. Delta and Omicron (B.1.1.529) Spike variants enhance and prolong viral attachment to the host, which likely not only increases the rate of viral uptake, but also enhances the resistance of the variants against host-cell detachment by shear forces such as airflow, mucus or blood flow. We uncover distinct binding mechanisms and strategies at single-molecule resolution, employed by circulating SARS-CoV-2 variants to enhance infectivity and viral transmission.

Resistance profile and mechanism of severe acute respiratory syndrome coronavirus-2 variants to LCB1 inhibitor targeting the spike receptor-binding motif.

LCB1 is a 56-mer miniprotein computationally designed to target the spike (S) receptor-binding motif of SARS-CoV-2 with potent in vitro and in vivo inhibitory activities (Cao et al., 2020; Case et al., 2021). However, the rapid emergence and epidemic of viral variants have greatly impacted the effectiveness of S protein-targeting vaccines and antivirals. In this study, we chemically synthesized a peptide-based LCB1 inhibitor and characterized the resistance profile and underlying mechanism of SARS-CoV-2 variants. Among five variants of concern (VOCs), we found that pseudoviruses of Beta, Gamma, and Omicron were highly resistant to the LCB1 inhibition, whereas the pseudoviruses of Alpha and Delta as well as the variant of interest (VOI) Lambda only caused mild resistance. By generating a group of mutant viruses carrying single or combination mutations, we verified that K417N and N501Y substitutions in RBD critically determined the high resistance phenotype of VOCs. Furthermore, a large panel of 85 pseudoviruses with naturally occurring RBD point-mutations were generated and applied to LCB1, which identified that E406Q, K417N, and L455F conferred high-levels of resistance, when Y505W caused a ∼6-fold resistance fold-change. We also showed that the resistance mutations could greatly weaken the binding affinity of LCB1 to RBD and thus attenuated its blocking capacity on the interaction between RBD and the cell receptor ACE2. In conclusion, our data have provided crucial information for understanding the mechanism of SARS-CoV-2 resistance to LCB1 and will guide the design strategy of novel LCB1-based antivirals against divergent VOCs and evolutionary mutants.

Potential inhibitors for blocking the interaction of the coronavirus SARS-CoV-2 spike protein and its host cell receptor ACE2

BackgroundThe outbreak of SARS-CoV-2 continues to pose a serious threat to human health and social. The ongoing pandemic of COVID-19 caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made a serious threat to public health and economic stability worldwide. Given the urgency of the situation, researchers are attempting to repurpose existing drugs for treating COVID-19.MethodsWe first established an anti-coronavirus drug screening platform based on the Homogeneous Time Resolved Fluorescence (HTRF) technology and the interaction between the coronavirus spike protein and its host receptor ACE2. Two compound libraries of 2,864 molecules were screened with this platform. Selected candidate compounds were validated by SARS-CoV-2_S pseudotyped lentivirus and ACE2-overexpressing cell system. Molecular docking was used to analyze the interaction between S protein and compounds.ResultsWe identified three potential anti-coronavirus compounds: tannic acid (TA), TS-1276 (anthraquinone), and TS-984 (9-Methoxycanthin-6-one). Our in vitro validation experiments indicated that TS-984 strongly inhibits the interaction of the coronavirus S protein and the human cell ACE2 receptor. Additionally, tannic acid showed moderate inhibitory effect on the interaction of S protein and ACE2.ConclusionThis platform is a rapid, sensitive, specific, and high throughput system, and available for screening large compound libraries. TS-984 is a potent blocker of the interaction between the S-protein and ACE2, which might have the potential to be developed into an effective anti-coronavirus drug.

An L-theanine derivative targets against SARS-CoV-2 and its Delta and Omicron variants

Recent research efforts have shown that tea has activities against SARS-CoV-2. However, the active compounds and the action mechanisms are largely unknown. Here we study the inhibitory potential of L-theanine from tea and its semi-synthesized derivative, a small-molecule fluorescent compound, ethyl 6-bromocoumarin-3-carboxylyl L-theanine (TBrC) against infection and replication of SARS-CoV-2 and the underlying mechanisms of action. We reveal that TBrC has potential activities against SARS-CoV-2 in addition to its activity against lung cancer. TBrC showed extracellular inhibition of SARS-CoV-2 Mpro/3CL and the host cell receptor ACE2 while interacting with the viral spike glycoproteins (wild-type, Delta, and Omicron mutants). Moreover, TBrC and L-theanine significantly suppressed growth and TNFα-induced nuclear transcriptional activation of NF-κB in human lung cancer cells without affecting the viability of normal lung cells, suggesting a potential protection of TBrC and L-theanine from pulmonary damages in SARS-CoV-2 infected patients, especially for lung cancer patients with SARS-CoV-2 infection.

Targeting different VOCs of SARS-CoV-2 and their host cell receptor ACE2 by potent phytochemical Orientin: an in silico approach

Targeting different VOCs of SARS-CoV-2 and their host cell receptor ACE2 by potent phytochemical Orientin: an in silico approach

Integrative structural studies of the SARS-CoV-2 spike protein during the fusion process (2022).

SARS-CoV-2 is the virus responsible for the COVID-19 pandemic and catastrophic, worldwide health and economic impacts. The spike protein on the viral surface is responsible for viral entry into the host cell. The binding of spike protein to the host cell receptor ACE2 is the first step leading to fusion of the host and viral membranes. Despite the vast amount of structure data that has been generated for the spike protein of SARS-CoV-2, many of the detailed structures of the spike protein in different stages of the fusion pathway are unknown, leaving a wealth of potential drug-target space unexplored. The atomic-scale structure of the complete S2 segment, as well as the complete fusion intermediate are also unknown and represent major gaps in our knowledge of the infectious pathway of SAR-CoV-2. The conformational changes of the spike protein during this process are similarly not well understood. Here we present structures of the spike protein at different stages of the fusion process. With the transitions being a necessary step before the receptor binding, we propose sites along the transition pathways as potential targets for drug development.

BRD2 inhibition blocks SARS-CoV-2 infection by reducing transcription of the host cell receptor ACE2.

SARS-CoV-2 infection of human cells is initiated by the binding of the viral Spike protein to its cell-surface receptor ACE2. We conducted a targeted CRISPRi screen to uncover druggable pathways controlling Spike protein binding to human cells. Here we show that the protein BRD2 is required for ACE2 transcription in human lung epithelial cells and cardiomyocytes, and BRD2 inhibitors currently evaluated in clinical trials potently block endogenous ACE2 expression and SARS-CoV-2 infection of human cells, including those of human nasal epithelia. Moreover, pharmacological BRD2 inhibition with the drug ABBV-744 inhibited SARS-CoV-2 replication in Syrian hamsters. We also found that BRD2 controls transcription of several other genes induced upon SARS-CoV-2 infection, including the interferon response, which in turn regulates the antiviral response. Together, our results pinpoint BRD2 as a potent and essential regulator of the host response to SARS-CoV-2 infection and highlight the potential of BRD2 as a therapeutic target for COVID-19.

Scoping review on the role and interactions of hydroxytyrosol and alpha-cyclodextrin in lipid-raft-mediated endocytosis of SARS-CoV-2 and bioinformatic molecular docking studies.

The aim of the study was to show the effect that two naturally occurring compounds, a cyclodextrin and hydroxytyrosol, can have on the entry of SARS-CoV-2 into human cells. The PubMed database was searched to retrieve studies published from 2000 to 2020, satisfying the inclusion criteria. The search keywords were: SARS-CoV, SARS-CoV-2, coronavirus, lipid raft, endocytosis, hydroxytyrosol, cyclodextrin. Modeling of alpha-cyclodextrin and hydroxytyrosol were done using UCSF Chimera 1.14. The search results indicated that cyclodextrins can reduce the efficiency of viral endocytosis and that hydroxytyrosol has antiviral properties. Bioinformatic docking studies showed that alpha-cyclodextrin and hydroxytyrosol, alone or in combination, interact with the viral spike protein and its host cell receptor ACE2, thereby potentially influencing the endocytosis process. Hydroxytyrosol and alpha-cyclodextrin can be useful against the spread of SARS-CoV-2.

Disulfide Bonds Play a Critical Role in the Structure and Function of the Receptor-binding Domain of the SARS-CoV-2 Spike Antigen

The current coronavirus pandemic is exerting a tremendously detrimental impact on global health. The Spike proteins of coronaviruses, responsible for cell receptor binding and viral internalization, possess multiple and frequently conserved disulfide bonds raising the question about their role in these proteins. Here, we present a detailed structural and functional investigation of the disulfide bonds of the SARS-CoV-2 Spike receptor-binding domain (RBD). Molecular dynamics simulations of the RBD predict increased flexibility of the surface loops when the four disulfide bonds of the domain are reduced. This flexibility is particularly prominent for the disulfide bond-containing surface loop (residues 456–490) that participates in the formation of the interaction surface with the Spike cell receptor ACE2. In vitro, disulfide bond reducing agents affect the RBD secondary structure, lower its melting temperature from 52 °C to 36–39 °C and decrease its binding affinity to ACE2 by two orders of magnitude at 37 °C. Consistent with these in vitro findings, the reducing agents tris(2-carboxyethyl)phosphine (TCEP) and dithiothreitol (DTT) were able to inhibit viral replication at low millimolar levels in cell-based assays. Our research demonstrates the mechanism by which the disulfide bonds contribute to the molecular structure of the RBD of the Spike protein, allowing the RBD to execute its viral function.

VTR: A Web Tool for Identifying Analogous Contacts on Protein Structures and Their Complexes.

Evolutionarily related proteins can present similar structures but very dissimilar sequences. Hence, understanding the role of the inter-residues contacts for the protein structure has been the target of many studies. Contacts comprise non-covalent interactions, which are essential to stabilize macromolecular structures such as proteins. Here we show VTR, a new method for the detection of analogous contacts in protein pairs. The VTR web tool performs structural alignment between proteins and detects interactions that occur in similar regions. To evaluate our tool, we proposed three case studies: we 1) compared vertebrate myoglobin and truncated invertebrate hemoglobin; 2) analyzed interactions between the spike protein RBD of SARS-CoV-2 and the cell receptor ACE2; and 3) compared a glucose-tolerant and a non-tolerant β-glucosidase enzyme used for biofuel production. The case studies demonstrate the potential of VTR for the understanding of functional similarities between distantly sequence-related proteins, as well as the exploration of important drug targets and rational design of enzymes for industrial applications. We envision VTR as a promising tool for understanding differences and similarities between homologous proteins with similar 3D structures but different sequences. VTR is available at http://bioinfo.dcc.ufmg.br/vtr.

Atomistic insight into 2D COFs as antiviral agents against SARS-CoV-2

The recent pandemic of COVID‐19 has raised global health concerns. Preventing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) activity in the body is a very promising method to overcome the COVID-19 pandemic. One of the prevention methods is constraining the binding process among the human cell receptor-ACE2 and coronavirus spike protein. In the research done, the effect of deformation of the spike protein structure, due to the covalent organic frameworks (COFs), in reducing the interactions of ACE2 and the spike protein by the computational method was investigated. In this regard, atomic analysis of the interactions of ACE2 and the spike protein is provided using a molecular dynamics simulation. First, we investigated the interactions of the three different COFs, including COF-78, DAAQ-TFP, and COF–OEt, with the spike protein by analyzing the bond energies, as well as structural changes of the spike protein. Then, intermolecular interactions of the deformed spike protein along with ACE2 were assessed to clarify the protein's fusion after the deformation. As indicated by the results, although all introduced COFs deformed the spike protein in an effective way, COF-78 showed the best performance in the prevention of spike protein-ACE2 interactions by changing the molecular structure of the protein. Indeed, the interaction analysis of the deformed spike protein by COF-78 with the ACE2 showed that their interactions had the lowest absolute value of energy, along with the least amount of hydrogen bonds, in which the compaction of the protein was lower compared to the other deformed proteins. Moreover, having a high contact area with an aqueous media as well as severe fluctuations during the simulation time confirmed the positive performance of COF-78. In the current study, we aimed to introduce novel materials and COVID-19 prevention methodology that can be used in face masks and for surface disinfection.

Natural Immunomodulators Treat the Cytokine Storm in SARS-CoV-2.

Recently, the world has been dealing with a destructive global pandemic Coronavirus disease 2019 (COVID-19) infection, since 2020; there were millions of infections and hundreds of thousands of deaths worldwide. With sequencing generations of the virus, around 60% are expected to become infected during the pandemic. Unfortunately, no drug or vaccine has been approved because no real evidence from clinical trials in treatment was reached. According to current thinking, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mortality is caused by a cytokine storm syndrome in patients with hyper-inflammatory conditions, resulting in acute respiratory distress and finally death. In this review, we discuss the various types of natural immune-modulatory agents and their role in the management of SARS-CoV-2, and cytokine storm syndrome. For example, Polyphenols as natural products can block the binding of SARS-CoV-2 spike protein to host cell receptor ACE2, stop viral entry into the host cell and block viral RNA replication. Also, saikosaponins (A, B2, C, and D), triterpene glycosides, which are isolated from medicinal plants exert antiviral action against HCoV-22E9, and Houttuynia cordata water extract has antiviral effects on SARS-CoV. Moreover, eucalyptus oil has promising potential for COVID-19 prevention and treatment. There is an urgent need for research to improve the function of the human immune system all over the world. As a result, actions for better understanding and improving the human immune system are critical steps toward mitigating risks and negative outcomes. These approaches will be strongly recommended for future emerging viruses and pathogens.

In vitro data suggest that Indian delta variant B.1.617 of SARS-CoV-2 escapes neutralization by both receptor affinity and immune evasion.

BackgroundEmerged mutations can be attributed to increased transmissibility of the B.1.617 and B.1.36 Indian delta variants of SARS‐CoV‐2, most notably substitutions L452R/E484Q and N440K, respectively, which occur in the receptor‐binding domain (RBD) of the Spike (S) fusion glycoprotein.ObjectiveWe aimed to assess the effects of mutations L452R/E484Q and N440K (as well as the previously studied mutation E484K present in variants B.1.351 and P.1) on the affinity of RBD for ACE2, SARS‐CoV‐2 main receptor. We also aimed to assess the ability of antibodies induced by natural infection or by immunization with BNT162b2 mRNA vaccine to recognize the mutated versions of the RBD, as well as blocking the interaction RBD‐ACE2, an important surrogate readout for virus neutralization.MethodsTo this end, we produced recombinant wild‐type RBD, as well as RBD containing each of the mutations L452R/E484Q, N440K, or E484K (the latest present in variants of concern B.1.351 and P.1), as well as the ectodomain of ACE2. Using Biolayer Interferometry (BLI), we measured the binding affinity of RBD for ACE2 and the ability of sera from COVID‐19 convalescent donors or subjects immunized with BNT162b2 mRNA vaccine to block this interaction. Finally, we correlated these results with total anti‐RBD IgG titers measured from the same sera by direct ELISA.ResultsThe binding assays showed L452R/E484Q double‐mutant RBD to interact with ACE2 with higher affinity (KD = 4.6 nM) than wild‐type (KD = 21.3 nM) or single mutants N440K (KD = 9.9 nM) and E484K (KD = 19.7 nM) RBDs. Meanwhile, the anti‐RBD IgG titration resulted in lower recognition of mutants E484K and L452R/E484Q by infection‐induced antibodies, whereas only mutant E484K was recognized less by antibodies induced by vaccination. More interestingly, sera from convalescent as well as immunized subjects showed reduced ability to block the interaction between ACE2 and RBD mutants E484K and L452R/E484Q, as shown by the inhibition assays.ConclusionOur data suggest that the newly emerged SARS‐CoV‐2 variant B.1.617, as well as the better‐studied variants B.1.351 and P.1 (all containing a mutation at position E484) display increased transmissibility both due to their higher affinity for the cell receptor ACE2 and their ability to partially bypass immunity generated against the wild‐type virus. For variant B.1.36 (with a point mutation at position N440), only increased affinity seems to play a role.