scholarly journals Spike Glycoprotein Is Central to Coronavirus Pathogenesis-Parallel Between m-CoV and SARS-CoV-2

2021 ◽  
pp. 097275312110237
Author(s):  
Fareeha Saadi ◽  
Debnath Pal ◽  
Jayasri Das Sarma
Keyword(s):  
Membrane Fusion ◽  
Viral Entry ◽  
Protein Function ◽  
Neutralizing Antibodies ◽  
Therapeutic Potential ◽  
Disease Process ◽  
Antigenic Determinants ◽  
S Protein ◽  
Host Immune Responses ◽  
Heptad Repeats

Coronaviruses (CoVs) are single-stranded, polyadenylated, enveloped RNA of positive polarity with a unique potential to alter host tropism. This has been exceptionally demonstrated by the emergence of deadly virus outbreaks of the past: Severe Acute Respiratory Syndrome (SARS-CoV) in 2003 and Middle East Respiratory Syndrome (MERS-CoV) in 2012. The 2019 outbreak by the new cross-species transmission of SARS-CoV-2 has put the world on alert. CoV infection is triggered by receptor recognition, membrane fusion, and successive viral entry mediated by the surface Spike (S) glycoprotein. S protein is one of the major antigenic determinants and the target for neutralizing antibodies. It is a valuable target in antiviral therapies because of its central role in cell-cell fusion, viral antigen spread, and host immune responses leading to immunopathogenesis. The receptor-binding domain of S protein has received greater attention as it initiates host attachment and contains major antigenic determinants. However, investigating the therapeutic potential of fusion peptide as a part of the fusion core complex assembled by the heptad repeats 1 and 2 (HR1 and HR2) is also warranted. Along with receptor attachment and entry, fusion mechanisms should also be explored for designing inhibitors as a therapeutic intervention. In this article, we review the S protein function and its role in mediating membrane fusion, spread, tropism, and its associated pathogenesis with notable therapeutic strategies focusing on results obtained from studies on a murine β-Coronavirus (m-CoV) and its associated disease process.

scholarly journals Amino Acids 1055 to 1192 in the S2 Region of Severe Acute Respiratory Syndrome Coronavirus S Protein Induce Neutralizing Antibodies: Implications for the Development of Vaccines and Antiviral Agents

2005 ◽  
Vol 79 (6) ◽  
pp. 3289-3296 ◽  
Author(s):  
Choong-Tat Keng ◽  
Aihua Zhang ◽  
Shuo Shen ◽  
Kuo-Ming Lip ◽  
Burtram C. Fielding ◽  
...  
Keyword(s):  
Amino Acids ◽  
Severe Acute Respiratory Syndrome ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Antiviral Agents ◽  
Host Cells ◽  
Heptad Repeat ◽  
Antigenic Determinants ◽  
Amino Acid Residues ◽  
S Protein

ABSTRACT The spike (S) protein of the severe acute respiratory syndrome coronavirus (SARS-CoV) interacts with cellular receptors to mediate membrane fusion, allowing viral entry into host cells; hence it is recognized as the primary target of neutralizing antibodies, and therefore knowledge of antigenic determinants that can elicit neutralizing antibodies could be beneficial for the development of a protective vaccine. Here, we expressed five different fragments of S, covering the entire ectodomain (amino acids 48 to 1192), as glutathione S-transferase fusion proteins in Escherichia coli and used the purified proteins to raise antibodies in rabbits. By Western blot analysis and immunoprecipitation experiments, we showed that all the antibodies are specific and highly sensitive to both the native and denatured forms of the full-length S protein expressed in virus-infected cells and transfected cells, respectively. Indirect immunofluorescence performed on fixed but unpermeabilized cells showed that these antibodies can recognize the mature form of S on the cell surface. All the antibodies were also able to detect the maturation of the 200-kDa form of S to the 210-kDa form by pulse-chase experiments. When the antibodies were tested for their ability to inhibit SARS-CoV propagation in Vero E6 culture, it was found that the anti-SΔ10 antibody, which was targeted to amino acid residues 1029 to 1192 of S, which include heptad repeat 2, has strong neutralizing activities, suggesting that this region of S carries neutralizing epitopes and is very important for virus entry into cells.

scholarly journals Glycans of SARS-CoV-2 Spike Protein in Virus Infection and Antibody Production

2021 ◽  
Vol 8 ◽  
Author(s):  
Xiaohui Zhao ◽  
Huan Chen ◽  
Hongliang Wang
Keyword(s):  
Immune Response ◽  
Antibody Production ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Protein Glycosylation ◽  
The Other ◽  
Defense System ◽  
S Protein ◽  
Receptor Interactions

Viral protein glycosylation represents a successful strategy employed by the parasite to take advantage of host–cell machinery for modification of its own proteins. The resulting glycans have unneglectable roles in viral infection and immune response. The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which presents on the surface of matured virion and mediates viral entry into the host, also undergoes extensive glycosylation to shield it from the human defense system. It is believed that the ongoing COVID-19 pandemic with more than 90,000,000 infections and 1,900,000 deaths is partly due to its successful glycosylation strategy. On the other hand, while glycan patches on S protein have been reported to shield the host immune response by masking “nonself” viral peptides with “self-glycans,” the epitopes are also important in eliciting neutralizing antibodies. In this review, we will summarize the roles of S protein glycans in mediating virus–receptor interactions, and in antibody production, as well as indications for vaccine development.

scholarly journals Effects of Spike Mutations in SARS-CoV-2 Variants of Concern on Human or Animal ACE2-Mediated Virus Entry and Neutralization

2021 ◽  
Author(s):  
Yunjeong Kim ◽  
Natasha N Gaudreault ◽  
David A Meekins ◽  
Krishani D Perera ◽  
Dashzeveg Bold ◽  
...  
Keyword(s):  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Animal Species ◽  
Virus Entry ◽  
Neutralizing Antibody ◽  
Protein S ◽  
Pseudotyped Virus ◽  
S Protein ◽  
Viral Neutralization ◽  
Wide Range

SARS-CoV-2 is a zoonotic agent capable of infecting humans and a wide range of animal species. Over the duration of the pandemic, mutations in the SARS-CoV-2 Spike protein (S) have arisen in circulating viral populations, culminating in the spread of several variants of concern (VOC) with varying degrees of altered virulence, transmissibility, and neutralizing antibody escape. In this study, we employed lentivirus-based pseudotyped viruses that express specific SARS-CoV-2 S protein substitutions and cell lines that stably express ACE2 from nine different animal species to gain insights into the effects of VOC mutations on viral entry and antibody neutralization capability. All animal ACE2 receptors tested, except mink, support viral cell entry for pseudoviruses expressing the parental (prototype Wuhan-1) S at levels comparable to human ACE2. Most single S substitutions (e.g., 452R, 478K, 501Y) did not significantly change virus entry, although 614G and 484K resulted in a decreased efficiency in viral entry.  Conversely, combinatorial VOC substitutions in the S protein were associated with significantly increased entry capacity of pseudotyped viruses compared to that of the parental Wuhan-1 pseudotyped virus. Similarly, infection studies using live ancestral (USA-WA1/2020), Alpha, and Beta SARS-CoV-2 viruses in hamsters revealed a higher replication potential for the Beta variant compared to the ancestral prototype virus. Moreover, neutralizing titers in sera from various animal species, including humans, were significantly reduced by single substitutions of 484K or 452R, double substitutions of 501Y-484K, 452R-484K and 452R-478K and the triple substitution of 501Y-484K-417N, suggesting that 484K and 452R are particularly important for evading neutralizing antibodies in human, cat, and rabbit sera. Cumulatively, this study reveals important insights into the host range of SARS-CoV-2 and the effect of recently emergent S protein substitutions on viral entry, virus replication and antibody-mediated viral neutralization.

scholarly journals SARS-CoV-2 Entry Inhibitors: Small Molecules and Peptides Targeting Virus or Host Cells

2020 ◽  
Vol 21 (16) ◽  
pp. 5707 ◽  
Author(s):  
Rolando Cannalire ◽  
Irina Stefanelli ◽  
Carmen Cerchia ◽  
Andrea R. Beccari ◽  
Sveva Pelliccia ◽  
...  
Keyword(s):  
Small Molecules ◽  
Viral Entry ◽  
Viral Infections ◽  
Host Factors ◽  
Host Cells ◽  
S Protein ◽  
Entry Inhibitors ◽  
Heptad Repeats ◽  
Direct Acting ◽  
Complementary Strategy

The pandemic evolution of SARS-CoV-2 infection is forcing the scientific community to unprecedented efforts to explore all possible approaches against COVID-19. In this context, targeting virus entry is a promising antiviral strategy for controlling viral infections. The main strategies pursued to inhibit the viral entry are considering both the virus and the host factors involved in the process. Primarily, direct-acting antivirals rely on inhibition of the interaction between ACE2 and the receptor binding domain (RBD) of the Spike (S) protein or targeting the more conserved heptad repeats (HRs), involved in the membrane fusion process. The inhibition of host TMPRSS2 and cathepsins B/L may represent a complementary strategy to be investigated. In this review, we discuss the development entry inhibitors targeting the S protein, as well as the most promising host targeting strategies involving TMPRSS2 and CatB/L, which have been exploited so far against CoVs and other related viruses.

scholarly journals Identification of an Antigenic Determinant on the S2 Domain of the Severe Acute Respiratory Syndrome Coronavirus Spike Glycoprotein Capable of Inducing Neutralizing Antibodies

2004 ◽  
Vol 78 (13) ◽  
pp. 6938-6945 ◽  
Author(s):  
Hong Zhang ◽  
Guangwen Wang ◽  
Jian Li ◽  
Yuchun Nie ◽  
Xuanling Shi ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Antigenic Determinant ◽  
Neutralizing Antibodies ◽  
Antigenic Structure ◽  
Antigenic Determinants ◽  
Structural Protein ◽  
Binding Ability ◽  
S Protein ◽  
Life Threatening ◽  
Carboxyl Terminal

ABSTRACT Severe acute respiratory syndrome (SARS) is a life-threatening disease caused by a newly identified coronavirus (CoV), SARS-CoV. The spike (S) glycoprotein of CoV is the major structural protein responsible for induction of host immune response and virus neutralization by antibodies. Hence, knowledge of neutralization determinants on the S protein is helpful for designing protective vaccines. To analyze the antigenic structure of the SARS-CoV S2 domain, the carboxyl-terminal half of the S protein, we first used sera from convalescent SARS patients to test the antigenicity of 12 overlapping fragments spanning the entire S2 and identified two antigenic determinants (Leu 803 to Ala 828 and Pro 1061 to Ser 1093). To determine whether neutralizing antibodies can be elicited by these two determinants, we immunized animals and found that both of them could induce the S2-specific antisera. In some animals, however, only one determinant (Leu 803 to Ala 828) was able to induce the antisera with the binding ability to the native S protein and the neutralizing activity to the SARS-CoV pseudovirus. This determinant is highly conserved across different SARS-CoV isolates. Identification of a conserved antigenic determinant on the S2 domain of the SARS-CoV S protein, which has the potential for inducing neutralizing antibodies, has implications in the development of effective vaccines against SARS-CoV.

scholarly journals Hepatitis C Virus Envelope Glycoprotein E2 Glycans Modulate Entry, CD81 Binding, and Neutralization

2007 ◽  
Vol 81 (15) ◽  
pp. 8072-8079 ◽  
Author(s):  
Emilia Falkowska ◽  
Francis Kajumo ◽  
Edie Garcia ◽  
John Reinus ◽  
Tatjana Dragic
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Entry ◽  
Protein Function ◽  
Neutralizing Antibodies ◽  
Target Cells ◽  
Virus Envelope ◽  
New Strategy ◽  
Viral Envelopes ◽  
Cd81 Binding

ABSTRACT Hepatitis C virus (HCV) is a major human pathogen that causes serious liver disease, including cirrhosis and hepatocellular carcinoma. The primary target cells of HCV are hepatocytes, and entry is restricted by interactions of the envelope glycoproteins, E1 and E2, with cellular receptors. E1 and E2 form noncovalently linked heterodimers and are heavily glycosylated. Glycans contribute to protein folding and transport as well as protein function. In addition, glycans associated with viral envelopes mask important functional domains from the immune system and attenuate viral immunogenicity. Here, we explored the role of N- and O-linked glycans on E2, which is the receptor binding subunit of the HCV envelope. We identified a number of glycans that are critical for viral entry. Importantly, we showed that the removal of several glycans significantly increased the inhibition of entry by sera from HCV-positive individuals. Only some of the glycans that affected entry and neutralization were also important for CD81 binding. Our results show that HCV envelope-associated glycans play a crucial role in masking functionally important regions of E2 and suggest a new strategy for eliciting highly neutralizing antibodies against this virus.

scholarly journals Insight into vaccine development for Alpha-coronaviruses based on structural and immunological analyses of spike proteins

2020 ◽  
Author(s):  
Yuejun Shi ◽  
Jiale Shi ◽  
Limeng Sun ◽  
Yubei Tan ◽  
Gang Wang ◽  
...  
Keyword(s):  
Public Health ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Neutralizing Antibody ◽  
Immune Recognition ◽  
Global Public Health ◽  
S Protein ◽  
Specific Antibodies ◽  
Major Target

AbstractCoronaviruses that infect humans belong to the Alpha-coronavirus (including HCoV-229E) and Beta-coronavirus (including SARS-CoV and SARS-CoV-2) genera. In particular, SARS-CoV-2 is currently a major threat to public health worldwide. However, no commercial vaccines against the coronaviruses that can infect humans are available. The spike (S) homotrimers bind to their receptors through the receptor-binding domain (RBD), which is believed to be a major target to block viral entry. In this study, we selected Alpha-coronavirus (HCoV-229E) and Beta-coronavirus (SARS-CoV and SARS-CoV-2) as models. Their RBDs were observed to adopt two different conformational states (lying or standing). Then, structural and immunological analyses were used to explore differences in the immune response with RBDs among these coronaviruses. Our results showed that more RBD-specific antibodies were induced by the S trimer with the RBD in the “standing” state (SARS-CoV and SARS-CoV-2) than the S trimer with the RBD in the “lying” state (HCoV-229E), and the affinity between the RBD-specific antibodies and S trimer was also higher in the SARS-CoV and SARS-CoV-2. In addition, we found that the ability of the HCoV-229E RBD to induce neutralizing antibodies was much lower and the intact and stable S1 subunit was essential for producing efficient neutralizing antibodies against HCoV-229E. Importantly, our results reveal different vaccine strategies for coronaviruses, and S-trimer is better than RBD as a target for vaccine development in Alpha-coronavirus. Our findings will provide important implications for future development of coronavirus vaccines.ImportanceOutbreak of coronaviruses, especially SARS-CoV-2, poses a serious threat to global public health. Development of vaccines to prevent the coronaviruses that can infect humans has always been a top priority. Coronavirus spike (S) protein is considered as a major target for vaccine development. Currently, structural studies have shown that Alpha-coronavirus (HCoV-229E) and Beta-coronavirus (SARS-CoV and SARS-CoV-2) RBDs are in lying and standing state, respectively. Here, we tested the ability of S-trimer and RBD to induce neutralizing antibodies among these coronaviruses. Our results showed that Beta-CoVs RBDs are in a standing state, and their S proteins can induce more neutralizing antibodies targeting RBD. However, HCoV-229E RBD is in a lying state, and its S protein induces a low level of neutralizing antibody targeting RBD. Our results indicate that Alpha-coronavirus is more conducive to escape host immune recognition, and also provide novel ideas for the development of vaccines targeting S protein.

scholarly journals Human IgG neutralizing monoclonal antibodies block SARS-CoV-2 infection

2020 ◽  
Author(s):  
Jinkai Wan ◽  
Shenghui Xing ◽  
Longfei Ding ◽  
Yongheng Wang ◽  
Dandan Zhu ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Therapeutic Potential ◽  
Memory B Cells ◽  
Antigen Binding ◽  
Receptor Binding Domain ◽  
Cell Cloning ◽  
Further Development ◽  
Cloning Technology

AbstractThe coronavirus induced disease 19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a worldwide threat to human lives, and neutralizing antibodies present a great therapeutic potential in curing affected patients. We purified more than one thousand memory B cells specific to SARS-CoV-2 S1 or RBD (receptor binding domain) antigens from 11 convalescent COVID-19 patients, and a total of 729 naturally paired heavy and light chain fragments were obtained by single B cell cloning technology. Among these, 178 recombinant monoclonal antibodies were tested positive for antigen binding, and the top 13 binders with Kd below 0.5 nM are all RBD binders. Importantly, all these 13 antibodies could block pseudoviral entry into HEK293T cells overexpressing ACE2, with the best ones showing IC50s around 2-3 nM. We further identified 8 neutralizing antibodies against authentic virus with IC50s within 10 nM. Among these, 414-1 blocked authentic viral entry at IC50 of 1.75 nM and in combination with 105-38 could achieve IC50 as low as 0.45 nM. Meanwhile, we also found that 3 antibodies could cross-react with the SARS-CoV spike protein. Altogether, our study provided a panel of potent human neutralizing antibodies for COVID19 as therapeutics candidates for further development.

scholarly journals Blockade of SARS-CoV-2 spike protein-mediated cell–cell fusion using COVID-19 convalescent plasma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ling Wang ◽  
Juan Zhao ◽  
Lam N. T. Nguyen ◽  
James L. Adkins ◽  
Madison Schank ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Cell Fusion ◽  
Neutralizing Antibodies ◽  
Molecular Mechanisms ◽  
Virus Entry ◽  
High Capacity ◽  
Target Cells ◽  
Global Public Health ◽  
S Protein ◽  
Cell Cell

AbstractThe recent COVID-19 pandemic poses a serious threat to global public health, thus there is an urgent need to define the molecular mechanisms involved in SARS-CoV-2 spike (S) protein-mediated virus entry that is essential for preventing and/or treating this emerging infectious disease. In this study, we examined the blocking activity of human COVID-19 convalescent plasma by cell–cell fusion assays using SARS-CoV-2-S-transfected 293 T as effector cells and ACE2-expressing 293 T as target cells. We demonstrate that the SARS-CoV-2 S protein exhibits a very high capacity for membrane fusion and is efficient in mediating virus fusion and entry into target cells. Importantly, we find that COVID-19 convalescent plasma with high titers of IgG neutralizing antibodies can block cell–cell fusion and virus entry by interfering with the SARS-CoV-2-S/ACE2 or SARS-CoV-S/ACE2 interactions. These findings suggest that COVID-19 convalescent plasma may not only inhibit SARS-CoV-2-S but also cross-neutralize SARS-CoV-S-mediated membrane fusion and virus entry, supporting its potential as a preventive and/or therapeutic agent against SARS-CoV-2 as well as other SARS-CoV infections.

Evaluation of Neutralizing Antibodies against Highly Pathogenic Coronaviruses: A Detailed Protocol for a Rapid Evaluation of Neutralizing Antibodies Using Vesicular Stomatitis Virus (Vsv) Pseudovirus-Based Assay

2020 ◽  
Author(s):  
Sarah A. Almahboub ◽  
Abdullah Algaissi ◽  
Mohamed A. Alfaleh ◽  
M-Zaki ElAssouli ◽  
Anwar M. Hashem
Keyword(s):  
Vesicular Stomatitis Virus ◽  
Viral Entry ◽  
Neutralizing Antibodies ◽  
Highly Pathogenic ◽  
S Protein ◽  
Level 3 ◽  
Vesicular Stomatitis ◽  
Biosafety Level ◽  
Detailed Protocol ◽  
S Proteins

Emerging highly pathogenic human coronaviruses (CoVs) represent a serious ongoing threat to the public health worldwide. The spike (S) proteins of CoVs are surface glycoproteins that facilitate viral entry into host cells via attachment to their respective cellular receptors. The S protein is believed to be a major immunogenic component of CoVs and a target for neutralizing antibodies (nAbs) and most candidate vaccines. Development of a safe and convenient assay is thus urgently needed to determine the prevalence of CoVs nAbs in the population, to study immune response in infected individuals, and to aid in vaccines and viral entry inhibitors evaluation. While live virus-based neutralization assays are used as gold standard serological methods to detect and measure nAbs, handling of highly pathogenic live CoVs requires strict bio-containment conditions in biosafety level-3 laboratories. On the other hand, use of replication-incompetent pseudoviruses bearing CoVs S proteins could represent a safe and useful method to detect nAbs in serum samples under biosafety level-2 conditions. Here, we describe a detailed protocol of a safe and convenient assay to generate vesicular stomatitis virus (VSV)-based pseudoviruses to evaluate and measure nAbs against highly pathogenic CoVs. The protocol covers methods to produce VSV pseudovirus bearing the S protein of the Middle East respiratory syndrome-CoV (MERS-CoV) and the severe acute respiratory syndrome-CoV-2 (SARS-CoV-2), pseudovirus titration, and pseudovirus neutralizing assay. Such assay could be adapted by different laboratories and researchers working on highly pathogenic CoVs without the need to handle live viruses in biosafety level-3 environment.

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