SARS-CoV-2 Spike RBD Recombinant Nanobody

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Datasheet

Code	CSB-RA33245A2GMY
Size	US$420
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Image	The Binding Activity of SARS-CoV-2 Spike RBD Nanobody with SARS-CoV-2-S1-RBD Activity: Measured by its binding ability in a functional ELISA. Immobilized SARS-CoV-2-S1-RBD (CSB-YP3324GMY1) at 2 μg/ml can bind SARS-CoV-2 Spike RBD Nanobody, the EC50 is 0.8674 ng/ml. In the Colloidal Gold Immunochromatography Assay detection system, the background of antibody (CSB-RA33245A2GMY) is clean, the detection limit can be as low as 25ng/ml (1.75ng/0.07ml), and the sensitivity is very good. SARS-CoV-2 Spike RBD Nanobody (CSB-RA33245A2GMY) competed with ACE2-HRP conjugate (CSB-MP866317HU) for binding to SARS-CoV-2-S1-RBD (CSB-YP3324GMY1). The binding signal of SARS-CoV-2-S1-RBD and ACE2-HRP conjugate was gradually reduced as the SARS-CoV-2 Spike RBD Nanobody concentrations increased. It indicated that this SARS-CoV-2 Spike RBD Nanobody effectively inhibited the SARS-CoV-2-S1-RBD/ACE2 binding. And the IC₅₀ of this SARS-CoV-2 Spike RBD Nanobody is 1.296 nM. SARS-CoV-2 Spike RBD Nanobody (CSB-RA33245A2GMY) competitively prevented SARS-CoV-2-S1-RBD (CSB-YP3324GMY1) from binding to ACE2-HRP conjugate (CSB-MP866317HU). The inhibition efficacy of the SARS-CoV-2-S1-RBD/ACE2 binding was positively proportionally to the SARS-CoV-2 Spike RBD Nanobody concentrations. It showed that this SARS-CoV-2 Spike RBD Nanobody effectively inhibited the SARS-CoV-2-S1-RBD/ACE2 binding. And the IC₅₀ of this SARS-CoV-2 Spike RBD Nanobody is 0.1074 μg/ml. SARS-CoV-2 Spike protein RBD His/Sumostar Tag (CSB-YP3324GMY1) captured on COOH chip binding to the SARS-CoV-2 Spike RBD Nanobody (CSB-RA33245A2GMY), increases the local refractive index (RI), leading to a red shift of the LSPR peak position. The higher concentrations of SARS-CoV-2 Spike RBD Nanobody, the larger the wavelength shift. The detected affinity constant of SARS-CoV-2 Spike protein RBD/SARS-CoV-2 Spike RBD Nanobody binding is 28.2nM. ELISA: Immobilize various types of SARS proteins at concentration of 2μg/ml on solid substrate, then react with SARS-CoV-2 Spike RBD Nanobody at concentration of 100μg/ml, 10μg/ml and 1μg/ml. It shows the SARS-CoV-2 Spike RBD Nanobody (CSB-RA33245A2GMY) is specific for SARS-CoV-2-S1-RBD protein, without any cross-reactivity with MERS-CoV, SARS-CoV, HCoV-OC43 or HCoV-229E.
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Product Details
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Target Background

Product Details

Uniprot No.

P0DTC2

Target Names

S (Spike glycoprotein)

Alternative Names

S; 2; Spike glycoprotein; S glycoprotein; E2; Peplomer protein)

Species Reactivity

Human Novel Coronavirus (SARS-CoV-2/ 2019-nCoV)

Immunogen

Recombinant Human Novel Coronavirus Spike glycoprotein(S) (319-541aa) (CSB-YP3324GMY1 and CSB-MP3324GMY1b1)

Immunogen Species

Human Novel Coronavirus (SARS-CoV-2/ 2019-nCoV)

Conjugate

Non-conjugated

Clonality

Monoclonal

Isotype

VHH fusion with human IgG1 Fc

Clone No.

Purification Method

Affinity-chromatography

Concentration

It differs from different batches. Please contact us to confirm it.

Buffer

Preservative: 0.03% Proclin 300
Constituents: 50% Glycerol, 0.01M PBS, pH 7.4

Form

Liquid

Tested Applications

ELISA, GICA, Neutralising

Recommended Dilution

Application	Recommended Dilution
ELISA	1:10000-1:100000
GICA	1:10000-1:40000
Neutralising	1:100-1:10000

Protocols

ELISA Protocol
CSB-RA33245A2GMY LSPR protocol

Troubleshooting and FAQs

Antibody FAQs

Storage

Upon receipt, store at -20°C or -80°C. Avoid repeated freeze.

Lead Time

Basically, we can dispatch the products out in 1-3 working days after receiving your orders. Delivery time maybe differs from different purchasing way or location, please kindly consult your local distributors for specific delivery time.

Description

The SARS-CoV-2 spike glycoprotein receptor-binding domain represents a critical interface in viral pathogenesis, mediating the initial attachment to human ACE2 receptors that enables cellular entry. This interaction has made the RBD a focal point for therapeutic development, diagnostic assay design, and fundamental studies of coronavirus biology.

This recombinant nanobody, derived from alpaca VHH sequences fused to a human IgG1 Fc domain, offers researchers a uniquely compact binding format with exceptional affinity. The recombinant production method ensures sequence-defined consistency between lots, eliminating the batch variability that can complicate longitudinal studies or assay standardization. Affinity chromatography purification delivers a reagent ready for demanding applications.

Validation data demonstrate impressive binding characteristics, with an EC50 of 0.8674 ng/ml in functional ELISA against immobilized S1-RBD and a measured affinity constant of 28.2 nM by surface plasmon resonance. Critically for neutralization studies, this nanobody effectively blocks the RBD-ACE2 interaction with an IC50 of 1.296 nM, providing a valuable tool for investigating viral entry mechanisms or developing competitive binding assays. Specificity testing confirms reactivity exclusively with SARS-CoV-2 S1-RBD, with no detectable binding to spike proteins from MERS-CoV, SARS-CoV, HCoV-OC43, or HCoV-229E, ensuring confidence in coronavirus-specific applications.

The antibody performs across multiple platforms including ELISA at dilutions from 1:10,000 to 1:100,000, colloidal gold immunochromatography assays with detection limits as low as 25 ng/ml, and neutralization studies. This versatility supports workflows ranging from high-throughput screening to rapid diagnostic development, making it a practical choice for virology research, vaccine evaluation studies, and infectious disease diagnostics.

Usage

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

Customer Reviews and Q&A

■ Customer Reviews

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■ Q&A

Where was CSB-RA33245A2GMY purified from? cell culture / hybridoma or serum / ascites?

It is a Nanobody that expressed from 293 cells (HEK293).

What is the concentration of this antibody, do you have this antibody in stock?

The concentration of CSB-RA33245A2GMY is 1mg/ml, we have stock for this antibody and the lead time is 1-2 working days.

I am interested in this product. What is the detection limit? Is it below 100-1000 SARS-CoV-2 particles?

We do not have information on the exact number of SARS-CoV-2 particles detected by the SARS-CoV-2 Spike RBD Nanobody. Please refer to the attached data sheet for the detection limit.

Is there any advantage of Nanobody compared with traditional hybridoma monoclonal antibody?

Compared with traditional hybridoma monoclonal antibody, the Nanobody has many advantages as below.
1. The homology between sequences of VH and VHH is very high, so the Nanobody can be humanized easily.
2. The Nanobodies are more likely to bind with antigens specifically, so the Nanobodies have a high affinity.
3. The Nanobodies are very stable on quality, because they can resistance high temperature, as well as have good solubility and strong penetration.
4. The Nanobodies have low immunogenicity and can recognize hidden epitopes.

What's the meaning of "Nanobody"?

The antibody contains only one heavy-chain variable region (VHH) and two regular CH2 and CH3 regions, but it does not stick to each other or even clump together as easily as the artificially engineered single-chain antibody fragment (scFv). More importantly, the independently cloned and expressed VHH structure has the same structural stability as the original heavy chain antibody and the binding activity with the antigen, which is the smallest unit of known binding target antigen, with the molecular weight of only 15KDa, also known as Nanobody (Nb).

What is the research significance of SARS-CoV-2 Spike RBD Nanobody?

The Nanobodies are very small in size, with a molecular weight of only 12-15 kDa, furthermore, Nanobodies have good biophysical properties, so they can be administered by inhalation, which makes Nanobodies particularly suitable for the treatment of respiratory diseases. Therefore, the SARS-CoV-2 Spike RBD Nanobody plays a very important role and has significance in the research of novel coronavirus.

In the Colloidal Gold Immunochromatography Assay, the detection limit was as low as 25ng/ml (1.75ng). Does it mean a concentration of 25ng/ml?

In the Colloidal Gold Immunochromatography Assay, the loading volume of sample is 70ul per test, and the concentration of sample is 25ng/ml, so the loading quantity of sample is 1.75ng.

Target Background

Function

attaches the virion to the cell membrane by interacting with host receptor, initiating the infection. Binding to human ACE2 receptor and internalization of the virus into the endosomes of the host cell induces conformational changes in the Spike glycoprotein. Binding to host NRP1 and NRP2 via C-terminal polybasic sequence enhances virion entry into host cell. This interaction may explain virus tropism of human olfactory epithelium cells, which express high level of NRP1 and NRP2 but low level of ACE2. The stalk domain of S contains three hinges, giving the head unexpected orientational freedom. Uses human TMPRSS2 for priming in human lung cells which is an essential step for viral entry. Can be alternatively processed by host furin. Proteolysis by cathepsin CTSL may unmask the fusion peptide of S2 and activate membranes fusion within endosomes.; mediates fusion of the virion and cellular membranes by acting as a class I viral fusion protein. Under the current model, the protein has at least three conformational states: pre-fusion native state, pre-hairpin intermediate state, and post-fusion hairpin state. During viral and target cell membrane fusion, the coiled coil regions (heptad repeats) assume a trimer-of-hairpins structure, positioning the fusion peptide in close proximity to the C-terminal region of the ectodomain. The formation of this structure appears to drive apposition and subsequent fusion of viral and target cell membranes.; Acts as a viral fusion peptide which is unmasked following S2 cleavage occurring upon virus endocytosis.; May down-regulate host tetherin (BST2) by lysosomal degradation, thereby counteracting its antiviral activity.

Gene References into Functions

Study presents crystal structure of C-terminal domain of SARS-CoV-2 (SARS-CoV-2-CTD) spike S protein in complex with human ACE2 (hACE2); hACE2-binding mode similar overall to that observed for SARS-CoV. However, details at the binding interface show that key residue substitutions in SARS-CoV-2-CTD slightly strengthen the interaction and lead to higher affinity for receptor binding than SARS-CoV receptor-binding domain. PMID: 32378705
crystal structure of the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 bound to the cell receptor ACE2 PMID: 32365751
crystal structure of the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 (engineered to facilitate crystallization) in complex with ACE2 PMID: 32320687
Out of the two isolates from India compared to the isolates from Wuhan, China, one was found to harbor a mutation in its receptor-binding domain (RBD) at position 407 where, arginine was replaced by isoleucine. This mutation has been seen to change the secondary structure of the protein at that region and this can potentially alter receptor binding of the virus. PMID: 32275855
Structural modeling of the SARS-CoV-2 spike glycoprotein show similar receptor utilization between SARS-CoV-2 and SARS-CoV, despite a relatively low amino acid similarity in the receptor binding module. Compared to SARS-CoV and all other coronaviruses in Betacoronavirus lineage B, an extended structural loop containing basic amino acids were identified at the interface of the receptor binding (S1) and fusion (S2) domains. PMID: 32245784
crystal structure of CR3022, a neutralizing antibody from a SARS patient, in complex with the receptor-binding domain of the SARS-CoV-2 spike (S) protein to 3.1 A; study provides insight into how SARS-CoV-2 can be targeted by the humoral immune response and revealed a conserved, but cryptic epitope shared between SARS-CoV-2 and SARS-CoV PMID: 32225176
SARS-CoV and SARS-CoV-2 spike proteins have comparable binding affinities achieved by balancing energetics and dynamics. The SARS-CoV-2-ACE2 complex contains a higher number of contacts, a larger interface area, and decreased interface residue fluctuations relative to the SARS-CoV-ACE2 complex. PMID: 32225175
Interaction interface between cat/dog/pangolin/Chinese hamster ACE2 and SARS-CoV/SARS-CoV-2 S protein was simulated through homology modeling. Authors identified that N82 of ACE2 showed closer contact with receptor-binding domain of S protein than human ACE2. PMID: 32221306
SARS-CoV-2 S glycoprotein harbors a furin cleavage site at the boundary between the S1/S2 subunits, which is processed during biogenesis and sets this virus apart from SARS-CoV and SARS-related CoVs; determined cryo-EM structures of the SARS-CoV-2 S ectodomain trimer. PMID: 32201080
Study demonstrates that SARS-CoV-2 uses the SARS-CoV receptor ACE2 for entry and the serine protease TMPRSS2 for S protein priming. PMID: 32155444
The ACE2-B0AT1 complex exists as a dimer of heterodimers. Structural alignment of the RBD-ACE2-B0AT1 ternary complex with the S protein of SARS-CoV-2 suggests that two S protein trimers can simultaneously bind to an ACE2 homodimer. PMID: 32142651
study demonstrated SARS-CoV-2 S protein entry on 293/hACE2 cells is mainly mediated through endocytosis, and PIKfyve, TPC2 and cathepsin L are critical for virus entry; found that SARS-CoV-2 S protein could trigger syncytia in 293/hACE2 cells independent of exogenous protease; there was limited cross-neutralization activity between convalescent sera from SARS and COVID-19 patients PMID: 32132184
study determined a 3.5-angstrom-resolution cryo-electron microscopy structure of the 2019-nCoV S trimer in the prefusion conformation; provided biophysical and structural evidence that the 2019-nCoV S protein binds angiotensin-converting enzyme 2 (ACE2) with higher affinity than does severe acute respiratory syndrome (SARS)-CoV S PMID: 32075877

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Subcellular Location

Virion membrane; Single-pass type I membrane protein. Host endoplasmic reticulum-Golgi intermediate compartment membrane; Single-pass type I membrane protein. Host cell membrane; Single-pass type I membrane protein.

Protein Families

Betacoronaviruses spike protein family

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