scholarly journals CD147-spike protein is a novel route for SARS-CoV-2 infection to host cells

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Ke Wang ◽  
Wei Chen ◽  
Zheng Zhang ◽  
Yongqiang Deng ◽  
Jian-Qi Lian ◽  
...  
Keyword(s):  
Virus Entry ◽  
Rapid Evolution ◽  
Cell Receptor ◽  
Host Cells ◽  
Spike Protein ◽  
Dependent Manner ◽  
Viral Loads ◽  
Host Cell Receptor ◽  
Human T Cells ◽  
Effective Drugs

AbstractIn face of the everlasting battle toward COVID-19 and the rapid evolution of SARS-CoV-2, no specific and effective drugs for treating this disease have been reported until today. Angiotensin-converting enzyme 2 (ACE2), a receptor of SARS-CoV-2, mediates the virus infection by binding to spike protein. Although ACE2 is expressed in the lung, kidney, and intestine, its expressing levels are rather low, especially in the lung. Considering the great infectivity of COVID-19, we speculate that SARS-CoV-2 may depend on other routes to facilitate its infection. Here, we first discover an interaction between host cell receptor CD147 and SARS-CoV-2 spike protein. The loss of CD147 or blocking CD147 in Vero E6 and BEAS-2B cell lines by anti-CD147 antibody, Meplazumab, inhibits SARS-CoV-2 amplification. Expression of human CD147 allows virus entry into non-susceptible BHK-21 cells, which can be neutralized by CD147 extracellular fragment. Viral loads are detectable in the lungs of human CD147 (hCD147) mice infected with SARS-CoV-2, but not in those of virus-infected wild type mice. Interestingly, virions are observed in lymphocytes of lung tissue from a COVID-19 patient. Human T cells with a property of ACE2 natural deficiency can be infected with SARS-CoV-2 pseudovirus in a dose-dependent manner, which is specifically inhibited by Meplazumab. Furthermore, CD147 mediates virus entering host cells by endocytosis. Together, our study reveals a novel virus entry route, CD147-spike protein, which provides an important target for developing specific and effective drug against COVID-19.

scholarly journals An ultrapotent synthetic nanobody neutralizes SARS-CoV-2 by stabilizing inactive Spike

Science ◽  
2020 ◽  
pp. eabe3255 ◽  
Author(s):  
Michael Schoof ◽  
Bryan Faust ◽  
Reuben A. Saunders ◽  
Smriti Sangwan ◽  
Veronica Rezelj ◽  
...  
Keyword(s):  
Cell Receptor ◽  
Affinity Maturation ◽  
Host Cells ◽  
Spike Protein ◽  
Airway Epithelia ◽  
Angiotensin Converting Enzyme 2 ◽  
Inactive Conformation ◽  
Binding Domains ◽  
Host Cell Receptor ◽  
Yeast Surface

The SARS-CoV-2 virus enters host cells via an interaction between its Spike protein and the host cell receptor angiotensin converting enzyme 2 (ACE2). By screening a yeast surface-displayed library of synthetic nanobody sequences, we developed nanobodies that disrupt the interaction between Spike and ACE2. Cryogenic electron microscopy (cryo-EM) revealed that one nanobody, Nb6, binds Spike in a fully inactive conformation with its receptor binding domains (RBDs) locked into their inaccessible down-state, incapable of binding ACE2. Affinity maturation and structure-guided design of multivalency yielded a trivalent nanobody, mNb6-tri, with femtomolar affinity for Spike and picomolar neutralization of SARS-CoV-2 infection. mNb6-tri retains function after aerosolization, lyophilization, and heat treatment, which enables aerosol-mediated delivery of this potent neutralizer directly to the airway epithelia.

scholarly journals The Importance of Therapeutically Targeting the Binary Toxin from Clostridioides difficile

2021 ◽  
Vol 22 (6) ◽  
pp. 2926
Author(s):  
Dinendra L. Abeyawardhane ◽  
Raquel Godoy-Ruiz ◽  
Kaylin A. Adipietro ◽  
Kristen M. Varney ◽  
Richard R. Rustandi ◽  
...  
Keyword(s):  
Host Cell ◽  
The Elderly ◽  
Cell Receptor ◽  
Host Cells ◽  
Binary Toxin ◽  
Clostridioides Difficile ◽  
Host Cell Receptor ◽  
Oligomeric Assembly ◽  
Nosocomial Disease ◽  
Binary Toxins

Novel therapeutics are needed to treat pathologies associated with the Clostridioides difficile binary toxin (CDT), particularly when C. difficile infection (CDI) occurs in the elderly or in hospitalized patients having illnesses, in addition to CDI, such as cancer. While therapies are available to block toxicities associated with the large clostridial toxins (TcdA and TcdB) in this nosocomial disease, nothing is available yet to treat toxicities arising from strains of CDI having the binary toxin. Like other binary toxins, the active CDTa catalytic subunit of CDT is delivered into host cells together with an oligomeric assembly of CDTb subunits via host cell receptor-mediated endocytosis. Once CDT arrives in the host cell’s cytoplasm, CDTa catalyzes the ADP-ribosylation of G-actin leading to degradation of the cytoskeleton and rapid cell death. Although a detailed molecular mechanism for CDT entry and host cell toxicity is not yet fully established, structural and functional resemblances to other binary toxins are described. Additionally, unique conformational assemblies of individual CDT components are highlighted herein to refine our mechanistic understanding of this deadly toxin as is needed to develop effective new therapeutic strategies for treating some of the most hypervirulent and lethal strains of CDT-containing strains of CDI.

Adherence of Legionella pneumophila to U-937 cells, guinea-pig alveolar macrophages, and MRC-5 cells by a novel, complement-independent binding mechanism

1994 ◽  
Vol 40 (10) ◽  
pp. 865-872 ◽  
Author(s):  
Frank C. Gibson III ◽  
Arthur O. Tzianabos ◽  
Frank G. Rodgers
Keyword(s):  
Monoclonal Antibodies ◽  
Guinea Pig ◽  
Host Cell ◽  
Alveolar Macrophages ◽  
Legionella Pneumophila ◽  
Cell Receptor ◽  
Host Cells ◽  
Order Kinetic ◽  
Complement Receptors ◽  
Host Cell Receptor

In the absence of serum, Legionella pneumophila demonstrated wash-resistant adherence to U-937 cells, primary guinea-pig alveolar macrophages, and MRC-5 cells. Neither complement nor antibody was required for binding. The dynamics of adherence following inoculation of L. pneumophila at increasing 10-fold multiplicities of infection to each of the three host cell types resulted in a first-order kinetic relationship of binding, indicative of one bacterial adhesin molecule recognized by one host cell receptor moiety. Host cell receptor saturation studies showed that depending on the cell type, 2–8% of the bacterial inoculum adhered to cells under these nonopsonic conditions. Preliminary adhesin and receptor characterization studies were preformed to define the chemical composition of the binding structures on both the organism and the three different host cell surfaces. The adherence phenomenon was investigated using competitive binding assays in the presence of putative adhesin analogs as well as following treatments modifying the microbial and host cell surface membranes. Attachment was evaluated both by viable bacterial cell colony counts and by indirect immunofluorescent assay. With the exception of aldehyde treatments, the various membrane-modifying regimes and the presence of the adhesin analogs were shown to have no effect on organism or host cell viability. Data suggested that the L. pneumophila adhesin responsible for opsonin-independent binding to these host cells was a protein structure with lectin-like properties. Furthermore, this protein would appear to be intimately associated with carbohydrate or lipid structures located on the bacterial outer membrane. The receptor moiety present on all host cells responsible for binding L. pneumophila had properties consistent with a carbohydrate or complex saccharide structure. To evaluate the role of complement receptors as the structures necessary for L. pneumophila infection of macrophages, a battery of monoclonal antibodies were used to block the complement receptor (CR) types 1 (CD35), CR3 (CD 18, CD11b), and CR4 (CD18, CD11c). Blocking studies with CR-specific monoclonal antibodies indicated that CR1 and the integrin receptors CR3 and CR4 were not involved in the opsonin-independent binding of L. pneumophila to macrophage-like cells.Key words: Legionella, opsonin-independent attachment, bacterial adherence, complement receptors, adhesion–receptor interactions.

scholarly journals Increasing Host Cellular Receptor—Angiotensin-Converting Enzyme 2 (ACE2) Expression by Coronavirus may Facilitate 2019-nCoV Infection

2020 ◽  
Author(s):  
Pei-Hui Wang ◽  
Yun Cheng
Keyword(s):  
Angiotensin Converting Enzyme ◽  
Emerging Infectious Diseases ◽  
Cell Receptor ◽  
Host Cells ◽  
Cellular Receptor ◽  
Converting Enzyme ◽  
Angiotensin Converting Enzyme 2 ◽  
Host Cell Receptor ◽  
Coronavirus Infection ◽  
Entry Receptor

AbstractThe ongoing outbreak of a new coronavirus (2019-nCoV) causes an epidemic of acute respiratory syndrome in humans. 2019-nCoV rapidly spread to national regions and multiple other countries, thus, pose a serious threat to public health. Recent studies show that spike (S) proteins of 2019-nCoV and SARS-CoV may use the same host cell receptor called angiotensin-converting enzyme 2 (ACE2) for entering into host cells. The affinity between ACE2 and 2019-nCoV S is much higher than ACE2 binding to SARS-CoV S protein, explaining that why 2019-nCoV seems to be more readily transmitted from the human to human. Here, we reported that ACE2 can be significantly upregulated after infection of various viruses including SARS-CoV and MERS-CoV. Basing on findings here, we propose that coronavirus infection can positively induce its cellular entry receptor to accelerate their replication and spread, thus drugs targeting ACE2 expression may be prepared for the future emerging infectious diseases caused by this cluster of viruses.

scholarly journals Can ChAdOx1, a replication-deficient adenoviral (Ad) vector used to deliver SARS-Cov2 spike protein as a vaccine, recombine with the homologous human Ad to generate a novel Ad+Spike virus?

2020 ◽  
Author(s):  
Sandeep Chakraborty
Keyword(s):  
Viral Vector ◽  
Rna Virus ◽  
Human Adenovirus ◽  
Cell Receptor ◽  
Spike Protein ◽  
Transcriptional Unit ◽  
Human Virus ◽  
Dna And Rna ◽  
Host Cell Receptor ◽  
Weakened Version

The development of a vaccine for Covid19 is being expedited [1]. The underlying technology for the vaccines are varied: ‘nucleic acid (DNA and RNA), virus-like particle, peptide, viral vector (replicating and non- replicating), recombinant protein, live attenuated virus and inactivated virus’ [2]. Among these, ChAdOx1, a genetically modified, weakened version of a common cold virus (adenovirus) is now in human clinical trials [3]. The ChAd vector (Chimpanzee adenovirus) was introduced in 2012 Chimpanzee adenovirus Y25 [4]. A large proportion of human adults possess significant titres of neutralising antibodies to human Adv, hence the requirement for a different adenovirus. The deletion of a single transcriptional unit, E1, ensures these viruses cant replicate. Other genes like the E3 region may also be deleted. Now, in the Covid19 vaccine ChAdOx1, the spike protein gene from MERS-CoV strain Camel/Qatar/2/2014 ‘was inserted into the E1 locus of a genomic clone of ChAdOx1 using site-specific recombination’ [5].One of the theories about the genesis of SARS-Cov2 is recombination with coronaviruses from pan- golins [6]. Whether or not it happened in SARS-Cov2, there is no denying that such recombinations do happen.How do we know that the spike protein wont be inserted into a human adenovirus using recombination?Human adenovirus shares 95% homology to ChAd. The spike protein may be inserted after the E1 protein in a viable human virus. What will happen after that to the virus is anyone’s guess. Note, that there is precedence for such recombinant adenoviruses - using ‘ping-pong” zoonosis and anthroponosis’, where the genome of a promiscuous pathogen is ‘embedded with evidence of unprecedented multiple, multidirectional, stable, and reciprocal cross-species infections of hosts from three species (human, chimpanzee, and bonobo)’ [7].Another critique - co-stimulation in host cellsA spike protein from SARS-Cov2, which is supposed to bind to ACE2 and CD147 [8], has been inserted in an adenovirus. The adenovirus has its own host-cell receptor preferences [9] - what will be the consequences of co-stimulation in those cells in which both these receptors are expressed?

scholarly journals An ultra-potent synthetic nanobody neutralizes SARS-CoV-2 by locking Spike into an inactive conformation

2020 ◽  
Author(s):  
Michael Schoof ◽  
Bryan Faust ◽  
Reuben A. Saunders ◽  
Smriti Sangwan ◽  
Veronica Rezelj ◽  
...  
Keyword(s):  
Viral Entry ◽  
Cell Receptor ◽  
Affinity Maturation ◽  
Host Cells ◽  
Angiotensin Converting Enzyme 2 ◽  
Inactive Conformation ◽  
Binding Domains ◽  
Host Cell Receptor ◽  
Yeast Surface ◽  
And Function

ABSTRACTWithout an effective prophylactic solution, infections from SARS-CoV-2 continue to rise worldwide with devastating health and economic costs. SARS-CoV-2 gains entry into host cells via an interaction between its Spike protein and the host cell receptor angiotensin converting enzyme 2 (ACE2). Disruption of this interaction confers potent neutralization of viral entry, providing an avenue for vaccine design and for therapeutic antibodies. Here, we develop single-domain antibodies (nanobodies) that potently disrupt the interaction between the SARS-CoV-2 Spike and ACE2. By screening a yeast surface-displayed library of synthetic nanobody sequences, we identified a panel of nanobodies that bind to multiple epitopes on Spike and block ACE2 interaction via two distinct mechanisms. Cryogenic electron microscopy (cryo-EM) revealed that one exceptionally stable nanobody, Nb6, binds Spike in a fully inactive conformation with its receptor binding domains (RBDs) locked into their inaccessible down-state, incapable of binding ACE2. Affinity maturation and structure-guided design of multivalency yielded a trivalent nanobody, mNb6-tri, with femtomolar affinity for SARS-CoV-2 Spike and picomolar neutralization of SARS-CoV-2 infection. mNb6-tri retains stability and function after aerosolization, lyophilization, and heat treatment. These properties may enable aerosol-mediated delivery of this potent neutralizer directly to the airway epithelia, promising to yield a widely deployable, patient-friendly prophylactic and/or early infection therapeutic agent to stem the worst pandemic in a century.

scholarly journals Host-cell recognition through GRP78 is enhanced in the new UK variant of SARS-CoV-2, in silico 

2021 ◽  
Author(s):  
Abdo A Elfiky ◽  
Ibrahim M Ibrahim
Keyword(s):  
Host Cell ◽  
Cell Receptor ◽  
Spike Protein ◽  
Cell Recognition ◽  
Receptor Binding Domain ◽  
Host Cell Receptor ◽  
Mutant Variant ◽  
New Variant ◽  
The Uk ◽  
Host Cell Recognition

Abstract New SARS-CoV-2 variant VUI 202012/01 started in the UK and currently spreading in Europe and Australia during the last few days. The new variant bears about nine mutations in the spike protein (Δ69-70, Δ145, N501Y, A570D, D614G, P681H, T716I, S982A, and D1118H). The N501Y lies in the receptor-binding domain (RBD) of the spike and interacts with the host-cell receptor ACE2 responsible for viral recognition and entry. We tried to simulate the system of ACE2-SARS-CoV-2 spike RBD in the wildtype and mutated isoform of the RBD (N501Y). Additionally, the GRP78 association with the ACE2-SARS-CoV-2 spike RBD is modeled at the presence of this mutant variant of the viral spike.

scholarly journals Elucidating Interactions Between SARS-CoV-2 Trimeric Spike Protein and ACE2 Using Homology Modeling and Molecular Dynamics Simulations

2021 ◽  
Vol 8 ◽  
Author(s):  
Sugunadevi Sakkiah ◽  
Wenjing Guo ◽  
Bohu Pan ◽  
Zuowei Ji ◽  
Gokhan Yavas ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Homology Modeling ◽  
Molecular Dynamics Simulations ◽  
Host Cell ◽  
Tertiary Structure ◽  
Cell Receptor ◽  
Host Cells ◽  
Spike Protein ◽  
Receptor Protein ◽  
Dynamics Simulations

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). As of October 21, 2020, more than 41.4 million confirmed cases and 1.1 million deaths have been reported. Thus, it is immensely important to develop drugs and vaccines to combat COVID-19. The spike protein present on the outer surface of the virion plays a major role in viral infection by binding to receptor proteins present on the outer membrane of host cells, triggering membrane fusion and internalization, which enables release of viral ssRNA into the host cell. Understanding the interactions between the SARS-CoV-2 trimeric spike protein and its host cell receptor protein, angiotensin converting enzyme 2 (ACE2), is important for developing drugs and vaccines to prevent and treat COVID-19. Several crystal structures of partial and mutant SARS-CoV-2 spike proteins have been reported; however, an atomistic structure of the wild-type SARS-CoV-2 trimeric spike protein complexed with ACE2 is not yet available. Therefore, in our study, homology modeling was used to build the trimeric form of the spike protein complexed with human ACE2, followed by all-atom molecular dynamics simulations to elucidate interactions at the interface between the spike protein and ACE2. Molecular Mechanics Poisson-Boltzmann Surface Area (MMPBSA) and in silico alanine scanning were employed to characterize the interacting residues at the interface. Twenty interacting residues in the spike protein were identified that are likely to be responsible for tightly binding to ACE2, of which five residues (Val445, Thr478, Gly485, Phe490, and Ser494) were not reported in the crystal structure of the truncated spike protein receptor binding domain (RBD) complexed with ACE2. These data indicate that the interactions between ACE2 and the tertiary structure of the full-length spike protein trimer are different from those between ACE2 and the truncated monomer of the spike protein RBD. These findings could facilitate the development of drugs and vaccines to prevent SARS-CoV-2 infection and combat COVID-19.

scholarly journals SARS - CoV - 2 Attachment to Host Cells is Possibly Mediated via RGD - Inte grin Interaction in a Calcium - dependent Manner

2020 ◽  
Author(s):  
TIKAM CHAND DAKAL
Keyword(s):  
Binding Affinity ◽  
Cell Attachment ◽  
Specific Treatment ◽  
Host Cells ◽  
Ion Concentration ◽  
Spike Protein ◽  
Lung Cells ◽  
Dependent Manner ◽  
Rgd Motif ◽  
Calcium Dependent

Our study revealed that SARS-CoV-2 harbors a RGD motif in its receptor binding domain (RBD) and the motif is absent in all previously known SARS-CoVs. The RGD motif plays a key role in cell-cell adhesion. Integrins display high affinity for RGD motifs and are known to bind to RGD motifs. Gene expression profiling revealed that expression of integrins is significantly high in lung cells, in particular αvβ6, α5β1, αvβ8 and an ECM protein, ICAM1. However, the expression of ACE2, which is a known receptor for SARS-CoV-2, was found to be negligible. The molecular docking experiment showed the RBD of spike protein binds with integrins precisely at RGD motif in a similar manner as a synthetic RGD peptide binds to integrins as found by other researchers. SARS-CoV-2 spike protein has a number of phosphorylation sites for cAMP, PKC, Tyr signaling pathways. These pathways either activate calcium ion channels or get activated by calcium. In fact, integrins have calcium & metal binding sites that were predicted around and in vicinity of RGD-integrin docking site suggesting RGD-integrins interaction occurs in calcium-dependent manner. The higher expression of integrins in lungs along with their previously known high binding affinity (~KD = 4.0nM) for virus RGD motif could serve as a possible explanation for high infectivity of SARS-CoV-2. On the contrary, the lower expression of human ACE2 in lungs and its low binding affinity (~KD= 15nM) for spike RBD suggests that human ACE2 is less likely to be a receptor for SARS-CoV-2, at least in lung cells. A highly relevant evidence never reported earlier which corroborate in favor of RGD-integrins mediated virus-host attachment is an unleashed cytokine storm which causes due to activation of TNF-α and IL-6 activation; and integrins role in their activation is also well established. Altogether, the current study highlighted the possible role of calcium and other divalent ions in RGD-integrins interaction for virus invasion into host cells and suggested that lowering divalent ion in lungs could avert virus-host cells attachment. Since, EDTA is well known chelating agent, we suggest pulmonary EDTA chelation therapy as a mean to phenotypically remodel the Ca+2 ion concentration in lungs to prevent RGD-integrin interaction which is dependent upon Ca+2 ion for facilitating virus-host cell attachment. The suggested therapy presents a novel, technically simple, quick, safe, affordable and effective solution to prevent SARS-CoV-2 infection and treat COVID 19, especially in the midst of global emergency when a specific treatment is inexistent.

scholarly journals The insert sequence in SARS-CoV-2 enhances spike protein cleavage by TMPRSS

2020 ◽  
Author(s):  
Tong Meng ◽  
Hao Cao ◽  
Hao Zhang ◽  
Zijian Kang ◽  
Da Xu ◽  
...  
Keyword(s):  
Insertion Sequence ◽  
Cell Receptor ◽  
Host Cells ◽  
Spike Protein ◽  
Target Cells ◽  
Cleavage Sites ◽  
Protein Cleavage ◽  
Protease Cleavage ◽  
Cleavage Efficiency ◽  
Protease Cleavage Sites

AbstractAt the end of 2019, the SARS-CoV-2 induces an ongoing outbreak of pneumonia in China1, even more spread than SARS-CoV infection2. The entry of SARS-CoV into host cells mainly depends on the cell receptor (ACE2) recognition and spike protein cleavage-induced cell membrane fusion3,4. The spike protein of SARS-CoV-2 also binds to ACE2 with a similar affinity, whereas its spike protein cleavage remains unclear5,6. Here we show that an insertion sequence in the spike protein of SARS-CoV-2 enhances the cleavage efficiency, and besides pulmonary alveoli, intestinal and esophagus epithelium were also the target tissues of SARS-CoV-2. Compared with SARS-CoV, we found a SPRR insertion in the S1/S2 protease cleavage sites of SARS-CoV-2 spike protein increasing the cleavage efficiency by the protein sequence aligment and furin score calculation. Additionally, the insertion sequence facilitates the formation of an extended loop which was more suitable for protease recognition by the homology modeling and molicular docking. Furthermore, the single-cell transcriptomes identified that ACE2 and TMPRSSs are highly coexpressed in AT2 cells of lung, along with esophageal upper epithelial cells and absorptive enterocytes. Our results provide the bioinformatics evidence for the increased spike protein cleavage of SARS-CoV-2 and indicate its potential target cells.

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