scholarly journals Single-amplicon, multiplex real-time RT-PCR with tiled probes to detect SARS-CoV-2 spike mutations associated with variants of concern

2021 ◽  
Author(s):  
Ahmed Babiker ◽  
Katherine Immergluck ◽  
Samuel D. Stampfer ◽  
Anuradha Rao ◽  
Leda Bassit ◽  
...  
Keyword(s):  
Real Time ◽  
Genome Sequencing ◽  
Receptor Binding ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Rt Pcr ◽  
Inexpensive Method ◽  
Single Amplicon ◽  
Single Primer ◽  
New Mutations

To provide an accessible and inexpensive method to surveil for SARS-CoV-2 mutations, we developed a multiplex real-time RT-PCR (the Spike SNP assay) to detect specific mutations in the spike receptor binding domain. A single primer pair was designed to amplify a 348 bp region of spike , and probes were initially designed to detect K417, E484K, and N501Y. The assay was evaluated using characterized variant sample pools and residual nasopharyngeal samples. Variant calls were confirmed by SARS-CoV-2 genome sequencing in a subset of samples. Subsequently, a fourth probe was designed to detect L452R. The lower limit of 95% detection was 2.46 to 2.48 log 10 GE/mL for the three initial targets (∼1-2 GE/reaction). Among 253 residual nasopharyngeal swabs with detectable SARS-CoV-2 RNA, the Spike SNP assay was positive in 238 (94.1%) samples. All 220 samples with Ct values < 30 for the SARS-CoV-2 N2 target were detected, whereas 18/33 samples with N2 Ct values ≥ 30 were detected. Spike SNP results were confirmed by sequencing in 50/50 samples (100%). Addition of the 452R probe did not affect performance for the original targets. The Spike SNP assay accurately identifies SARS-CoV-2 mutations in receptor binding domain, and it can be quickly modified to detect new mutations that emerge.

scholarly journals A Novel Real-Time RT-PCR-Based Methodology for the Preliminary Typing of SARS-CoV-2 Variants, Employing Non-Extendable LNA Oligonucleotides and Three Signature Mutations at the Spike Protein Receptor-Binding Domain

Life ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1015
Author(s):  
Serafeim C. Chaintoutis ◽  
Taxiarchis Chassalevris ◽  
Sofia Balaska ◽  
Evangelia Mouchtaropoulou ◽  
George Tsiolas ◽  
...  
Keyword(s):  
Amino Acid ◽  
Real Time ◽  
Receptor Binding ◽  
Binding Domain ◽  
Locked Nucleic Acid ◽  
Spike Protein ◽  
Amino Acid Substitutions ◽  
Receptor Binding Domain ◽  
Rt Pcr ◽  
Protein Receptor

Mutations resulting in amino-acid substitutions of the SARS-CoV-2 spike protein receptor-binding domain (RBD) have been associated with enhanced transmissibility and immune escape of the respective variants, namely Alpha, Beta, Gamma or Delta. Rapid identification of the aforementioned variants of concern and their discrimination of other variants is thus of importance for public health interventions. For this reason, a one-step real-time RT-PCR assay employing four locked nucleic acid (LNA) modified TaqMan probes was developed, to target signature mutations associated with amino-acid substitutions at positions 478, 484 and 501 present in the receptor-binding motif (RBM) of the spike protein RBD. This region contains most contacting residues of SARS-CoV-2 that bind to ACE2. A novel strategy employing the use of non-extendable LNA oligonucleotide blockers that can reduce non-specific hybridization of probes increased the number of different mutated sites examined in a multiplex PCR. The combinatory analysis of the different fluorescence signals obtained enabled the preliminary differentiation of SARS-CoV-2 variants of concern. The assay is sensitive with a LOD of 263 copies/reaction for the Delta variant, 170 copies/reaction for the Beta variant, amplification efficiencies > 91% and a linear range of >5 log10 copies/reaction against all targets. Validation of the assay using known SARS-CoV-2-positive and negative samples from humans and animals revealed its ability to correctly identify the targeted mutations and preliminary characterize the SARS-CoV-2 variants. The novel approach for mutation typing using LNA oligonucleotide blockers can be modified to target signature mutations at four different sites in the RBM and further expand the range of variants detected.

scholarly journals Development of a Fast SARS-CoV-2 IgG ELISA, Based on Receptor-Binding Domain, and Its Comparative Evaluation Using Temporally Segregated Samples From RT-PCR Positive Individuals

2021 ◽  
Vol 11 ◽  
Author(s):  
Farha Mehdi ◽  
Souvick Chattopadhyay ◽  
Ramachandran Thiruvengadam ◽  
Sarla Yadav ◽  
Manjit Kumar ◽  
...  
Keyword(s):  
Antibody Response ◽  
Receptor Binding ◽  
Neutralizing Antibodies ◽  
Elisa Test ◽  
Binding Domain ◽  
Antibody Detection ◽  
Receptor Binding Domain ◽  
Rt Pcr ◽  
Vaccine Response ◽  
Higher Sensitivity

SARS-CoV-2 antibody detection assays are crucial for gathering seroepidemiological information and monitoring the sustainability of antibody response against the virus. The SARS-CoV-2 Spike protein’s receptor-binding domain (RBD) is a very specific target for anti-SARS-CoV-2 antibodies detection. Moreover, many neutralizing antibodies are mapped to this domain, linking antibody response to RBD with neutralizing potential. Detection of IgG antibodies, rather than IgM or total antibodies, against RBD is likely to play a larger role in understanding antibody-mediated protection and vaccine response. Here we describe a rapid and stable RBD-based IgG ELISA test obtained through extensive optimization of the assay components and conditions. The test showed a specificity of 99.79% (95% CI: 98.82–99.99%) in a panel of pre-pandemic samples (n = 470) from different groups, i.e., pregnancy, fever, HCV, HBV, and autoantibodies positive. Test sensitivity was evaluated using sera from SARS-CoV-2 RT-PCR positive individuals (n = 312) and found to be 53.33% (95% CI: 37.87–68.34%), 80.47% (95% CI: 72.53–86.94%), and 88.24% (95% CI: 82.05–92.88%) in panel 1 (days 0–13), panel 2 (days 14–20) and panel 3 (days 21–27), respectively. Higher sensitivity was achieved in symptomatic individuals and reached 92.14% (95% CI: 86.38–96.01%) for panel 3. Our test, with a shorter runtime, showed higher sensitivity than parallelly tested commercial ELISAs for SARS-CoV-2-IgG, i.e., Euroimmun and Zydus, even when equivocal results in the commercial ELISAs were considered positive. None of the tests, which are using different antigens, could detect anti-SARS-CoV-2 IgGs in 10.5% RT-PCR positive individuals by the fourth week, suggesting the lack of IgG response.

Destabilizing the Structural Integrity of SARS-CoV2 Receptor Proteins by Curcumin Along with Hydroxychloroquine: An Insilco Approach for a Combination Therapy

2020 ◽  
Author(s):  
Akhileshwar Srivastava ◽  
Divya Singh
Keyword(s):  
Binding Energy ◽  
Combination Therapy ◽  
Receptor Binding ◽  
Structural Integrity ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Receptor Proteins ◽  
Main Protease ◽  
The Stability ◽  
Therapeutic Activities

Presently, an emerging disease (COVID-19) has been spreading across the world due to coronavirus (SARS-CoV2). For treatment of SARS-CoV2 infection, currently hydroxychloroquine has been suggested by researchers, but it has not been found enough effective against this virus. The present study based on in silico approaches was designed to enhance the therapeutic activities of hydroxychloroquine by using curcumin as an adjunct drug against SARS-CoV2 receptor proteins: main-protease and S1 receptor binding domain (RBD). The webserver (ANCHOR) showed the higher protein stability for both receptors with disordered score (<0.5). The molecular docking analysis revealed that the binding energy (-24.58 kcal/mol) of hydroxychloroquine was higher than curcumin (-20.47 kcal/mol) for receptor main-protease, whereas binding energy of curcumin (<a>-38.84</a> kcal/mol) had greater than hydroxychloroquine<a> (-35.87</a> kcal/mol) in case of S1 receptor binding domain. Therefore, this study suggested that the curcumin could be used as combination therapy along with hydroxychloroquine for disrupting the stability of SARS-CoV2 receptor proteins

Role of key point Mutations in Receptor Binding Domain of SARS-CoV-2 Spike Glycoprotein

2020 ◽  
Vol 20 ◽  
Author(s):  
Bipin Singh
Keyword(s):  
Receptor Binding ◽  
Point Mutations ◽  
Binding Domain ◽  
Receptor Binding Domain ◽  
Spike Glycoprotein ◽  
Angiotensin Converting Enzyme 2 ◽  
Recent Outbreak ◽  
Novel Coronavirus ◽  
Genomic Similarity

: The recent outbreak of novel coronavirus (SARS-CoV-2 or 2019-nCoV) and its worldwide spread is posing one of the major threats to human health and the world economy. It has been suggested that SARS-CoV-2 is similar to SARSCoV based on the comparison of the genome sequence. Despite the genomic similarity between SARS-CoV-2 and SARSCoV, the spike glycoprotein and receptor binding domain in SARS-CoV-2 shows the considerable difference compared to SARS-CoV, due to the presence of several point mutations. The analysis of receptor binding domain (RBD) from recently published 3D structures of spike glycoprotein of SARS-CoV-2 (Yan, R., et al. (2020); Wrapp, D., et al. (2020); Walls, A. C., et al. (2020)) highlights the contribution of a few key point mutations in RBD of spike glycoprotein and molecular basis of its efficient binding with human angiotensin-converting enzyme 2 (ACE2).

scholarly journals Ivermectin Docks to the SARS-CoV-2 Spike Receptor-binding Domain Attached to ACE2

In Vivo ◽  
2020 ◽  
Vol 34 (5) ◽  
pp. 3023-3026 ◽  
Author(s):  
STEVEN LEHRER ◽  
PETER H. RHEINSTEIN
Keyword(s):  
Receptor Binding ◽  
Binding Domain ◽  
Receptor Binding Domain

scholarly journals Neutralization of SARS‐CoV‐2 requires antibodies against conformational receptor‐binding domain epitopes

Allergy ◽  
2021 ◽  
Author(s):  
Pia Gattinger ◽  
Katarzyna Niespodziana ◽  
Karin Stiasny ◽  
Sabina Sahanic ◽  
Inna Tulaeva ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Binding Domain ◽  
Receptor Binding Domain
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