A novel antibody against the furin cleavage site of SARS-CoV-2 spike protein: Effects on proteolytic cleavage and ACE2 binding.
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ABSTRACT:
SUBMITTER: Spelios MG
PROVIDER: S-EPMC8739817 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Compared with other SARS-related coronaviruses (SARSr-CoVs), SARS-CoV-2 possesses a unique furin cleavage site (FCS) in its spike. This has stimulated discussion pertaining to the origin of SARS-CoV-2 because the FCS has been observed to be under strong selective pressure in humans and confers the enhanced ability to infect some cell types and induce cell-cell fusion. Furthermore, scientists have demonstrated interest in studying novel cleavage sites by introducing them into SARSr-CoVs. We review what is known about the SARS-CoV-2 FCS in the context of its pathogenesis, origin, and how future wildlife coronavirus sampling may alter the interpretation of existing data.
| S-EPMC8689951 | biostudies-literature
Project description:BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the global coronavirus disease 2019 (COVID-19) pandemic, contains a unique, four amino acid (aa) "PRRA" insertion in the spike (S) protein that creates a transmembrane protease serine 2 (TMPRSS2)/furin cleavage site and enhances viral infectivity. More research into immunogenic epitopes and protective antibodies against this SARS-CoV-2 furin cleavage site is needed.MethodsCombining computational and experimental methods, we identified and characterized an immunogenic epitope overlapping the furin cleavage site that detects antibodies in COVID-19 patients and elicits strong antibody responses in immunized mice. We also identified a high-affinity monoclonal antibody from COVID-19 patient peripheral blood mononuclear cells; the antibody directly binds the furin cleavage site and protects against SARS-CoV-2 infection in a mouse model.FindingsThe presence of "PRRA" amino acids in the S protein of SARS-CoV-2 not only creates a furin cleavage site but also generates an immunogenic epitope that elicits an antibody response in COVID-19 patients. An antibody against this epitope protected against SARS-CoV-2 infection in mice.InterpretationThe immunogenic epitope and protective antibody we have identified may augment our strategy in handling COVID-19 epidemic.FundingThe National Natural Science Foundation of China (82102371, 91542201, 81925025, 82073181, and 81802870), the Chinese Academy of Medical Sciences Initiative for Innovative Medicine (2021-I2M-1-047 and 2022-I2M-2-004), the Non-profit Central Research Institute Fund of the Chinese Academy of Medical Sciences (2020-PT310-006, 2019XK310002, and 2018TX31001), the National Key Research and Development Project of China (2020YFC0841700), US National Institute of Health (NIH) funds grant AI158154, University of California Los Angeles (UCLA) AI and Charity Treks, and UCLA DGSOM BSCRC COVID-19 Award Program. H.Y. is supported by Natural Science Foundation of Jiangsu Province (BK20211554 andBE2022728).
| S-EPMC9732504 | biostudies-literature
Project description:The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has resulted in tremendous loss worldwide. Although viral spike (S) protein binding of angiotensin-converting enzyme 2 (ACE2) has been established, the functional consequences of the initial receptor binding and the stepwise fusion process are not clear. By utilizing a cell-cell fusion system, in complement with a pseudoviral infection model, we found that the spike engagement of ACE2 primed the generation of S2' fragments in target cells, a key proteolytic event coupled with spike-mediated membrane fusion. Mutagenesis of an S2' cleavage site at the arginine (R) 815, but not an S2 cleavage site at arginine 685, was sufficient to prevent subsequent syncytia formation and infection in a variety of cell lines and primary cells isolated from human ACE2 knock-in mice. The requirement for S2' cleavage at the R815 site was also broadly shared by other SARS-CoV-2 spike variants, such as the Alpha, Beta, and Delta variants of concern. Thus, our study highlights an essential role for host receptor engagement and the key residue of spike for proteolytic activation, and uncovers a targetable mechanism for host cell infection by SARS-CoV-2.
| S-EPMC8740742 | biostudies-literature
Project description:The furin cleavage site in the spike glycoprotein of the SARS-CoV-2 coronavirus is considered important for the virus to enter the host cells. By analyzing 45828 SARS-CoV-2 genome sequences, we identified 103 strains of SARS-CoV-2 with various DNA mutations including 18 unique non-synonymous point mutations, one deletion, and six gains of premature stop codon that may affect the furin cleavage site. Our results revealed that the furin cleavage site might not be required for SARS-CoV-2 to enter human cells in vivo. The identified mutants may represent a new subgroup of SARS-CoV-2 coronavirus with reduced tropism and transmissibility as potential live-attenuated vaccine candidates.
| S-EPMC7379507 | biostudies-literature
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-a new coronavirus that has led to a worldwide pandemic1-has a furin cleavage site (PRRAR) in its spike protein that is absent in other group-2B coronaviruses2. To explore whether the furin cleavage site contributes to infection and pathogenesis in this virus, we generated a mutant SARS-CoV-2 that lacks the furin cleavage site (ΔPRRA). Here we report that replicates of ΔPRRA SARS-CoV-2 had faster kinetics, improved fitness in Vero E6 cells and reduced spike protein processing, as compared to parental SARS-CoV-2. However, the ΔPRRA mutant had reduced replication in a human respiratory cell line and was attenuated in both hamster and K18-hACE2 transgenic mouse models of SARS-CoV-2 pathogenesis. Despite reduced disease, the ΔPRRA mutant conferred protection against rechallenge with the parental SARS-CoV-2. Importantly, the neutralization values of sera from patients with coronavirus disease 2019 (COVID-19) and monoclonal antibodies against the receptor-binding domain of SARS-CoV-2 were lower against the ΔPRRA mutant than against parental SARS-CoV-2, probably owing to an increased ratio of particles to plaque-forming units in infections with the former. Together, our results demonstrate a critical role for the furin cleavage site in infection with SARS-CoV-2 and highlight the importance of this site for evaluating the neutralization activities of antibodies.
| S-EPMC8175039 | biostudies-literature
Project description:SARS-CoV-2 has resulted in a global pandemic and shutdown economies around the world. Sequence analysis indicates that the novel coronavirus (CoV) has an insertion of a furin cleavage site (PRRAR) in its spike protein. Absent in other group 2B CoVs, the insertion may be a key factor in the replication and virulence of SARS-CoV-2. To explore this question, we generated a SARS-CoV-2 mutant lacking the furin cleavage site (ΔPRRA) in the spike protein. This mutant virus replicated with faster kinetics and improved fitness in Vero E6 cells. The mutant virus also had reduced spike protein processing as compared to wild-type SARS-CoV-2. In contrast, the ΔPRRA had reduced replication in Calu3 cells, a human respiratory cell line, and had attenuated disease in a hamster pathogenesis model. Despite the reduced disease, the ΔPRRA mutant offered robust protection from SARS-CoV-2 rechallenge. Importantly, plaque reduction neutralization tests (PRNT 50 ) with COVID-19 patient sera and monoclonal antibodies against the receptor-binding domain found a shift, with the mutant virus resulting in consistently reduced PRNT 50 titers. Together, these results demonstrate a critical role for the furin cleavage site insertion in SARS-CoV-2 replication and pathogenesis. In addition, these findings illustrate the importance of this insertion in evaluating neutralization and other downstream SARS-CoV-2 assays.ImportanceAs COVID-19 has impacted the world, understanding how SARS-CoV-2 replicates and causes virulence offers potential pathways to disrupt its disease. By removing the furin cleavage site, we demonstrate the importance of this insertion to SARS-CoV-2 replication and pathogenesis. In addition, the findings with Vero cells indicate the likelihood of cell culture adaptations in virus stocks that can influence reagent generation and interpretation of a wide range of data including neutralization and drug efficacy. Overall, our work highlights the importance of this key motif in SARS-CoV-2 infection and pathogenesis.Article summaryA deletion of the furin cleavage site in SARS-CoV-2 amplifies replication in Vero cells, but attenuates replication in respiratory cells and pathogenesis in vivo. Loss of the furin site also reduces susceptibility to neutralization in vitro .
| S-EPMC7457603 | biostudies-literature
Project description: Not available
| EMPIAR-11181 | biostudies-other
Project description:The SARS-CoV-2 coronavirus responsible for the global pandemic contains a unique furin cleavage site in the spike protein (S) that increases viral infectivity and syncytia formation. Here, we show that O-glycosylation near the furin cleavage site is mediated by specific members of the GALNT enzyme family and is dependent on the novel proline at position 681 (P681). We further demonstrate that O-glycosylation of S decreases furin cleavage. Finally, we show that GALNT family members capable of glycosylating S are expressed in human respiratory cells that are targets for SARS-CoV-2 infection. Our results suggest that O-glycosylation may influence viral infectivity/tropism by modulating furin cleavage of S and provide mechanistic insight into the potential role of P681 mutations in the recently identified, highly transmissible B.1.1.7 variant.
| S-EPMC7872346 | biostudies-literature
Project description:The novel coronavirus disease 2019 (COVID-19) is a global epidemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). SARS-CoV-2 has a similar structure to severe acute respiratory syndrome coronavirus-1(SARS-CoV-1). The S protein on the surface of the virus is cleaved by host proprotein convertases (PCs) to expose the active N-terminal S1 extracellular domain. Its receptors are angiotensin-converting enzyme 2 (ACE2), and the C-terminal S2 membrane anchoring protein is responsible for translocating the virus into the cell. Among patients with COVID-19, there is a higher prevalence of cardiovascular disease, and more than 7% of patients have suffered myocardial damage due to the infection, but the internal mechanism is still poorly understood. There is currently no specific and effective targeted treatment. Reduction of the patient's morbidity and mortality is an urgent problem that needs to be solved clinically. By exploring the theoretical analysis of PCs and ACE2 in COVID-19 cardiovascular susceptibility, some insights on how to prevent and alleviate adverse cardiovascular prognosis have been provided in this study.
| S-EPMC7352091 | biostudies-literature
Project description:SARS-CoV-2 pathogenesis, vaccine, and therapeutic studies rely on the use of animals challenged with highly pathogenic virus stocks produced in cell cultures. Ideally, these virus stocks should be genetically and functionally similar to the original clinical isolate, retaining wild-type properties to be reliably used in animal model studies. It is well-established that SARS-CoV-2 isolates serially passaged on Vero cell lines accumulate mutations and deletions in the furin cleavage site; however, these can be eliminated when passaged on Calu-3 lung epithelial cell lines, as presented in this study. As numerous stocks of SARS-CoV-2 variants of concern are being grown in cell cultures with the intent for use in animal models, it is essential that propagation methods generate virus stocks that are pathogenic in vivo. Here, we found that the propagation of a B.1.351 SARS-CoV-2 stock on Calu-3 cells eliminated viruses that previously accumulated mutations in the furin cleavage site. Notably, there were alternative variants that accumulated at the same nucleotide positions in virus populations grown on Calu-3 cells at multiple independent facilities. When a Calu-3-derived B.1.351 virus stock was used to infect hamsters, the virus remained pathogenic and the Calu-3-specific variants persisted in the population. These results suggest that Calu-3-derived virus stocks are pathogenic but care should still be taken to evaluate virus stocks for newly arising mutations during propagation.
| S-EPMC8704555 | biostudies-literature