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SARS-CoV-2 Spike S1 Rabbit Monoclonal Antibody Development Service

COVID-19 Virus Spike S1 Monoclonal Antibodies, 2019-nCoV Spike RBD Monoclonal Antibodies

Catalog No. Product Name Size List Price (US$) Quantity
BS091 SARS-CoV-2 Spike S1 Rabbit Monoclonal Antibody Development Service 1 package Request

BS091: Anti-SARS-CoV-2 Spike Protein S1 Subunit and RBD Recombinant Rabbit Monoclonal Antibodies (mAbs)

We immunized rabbits with SARS-CoV-2 S protein S1 subunit, identified a number of anti-Spike S1 and RBD rabbit monoclonal antibodies (mAbs), sequenced and cloned the antibody genes, then expressed and purified the recombinant rabbit Spike S1 protein monoclonal antibodies and Spike RBD mAbs. We measured antigen binding affinity and pairing possibility of some recombinant rabbit mAbs, which can be used for clinical diagnostics to detect the SARS-CoV-2 antigen. Some RBD rabbit mAbs even have the neutralization function to block the RBD-ACE2 interaction, which is critical for antibody discovery for therapeutics. The feature of our S1 and RBD recombinant rabbit mAbs:

High sensitivity: the affinity to the SARS-CoV-2 S1 subunit and RBD domain measured by the Biacore method is as low as 300 pM.

Antibody pairing: the recombinant rabbit mAbs bind to various epitopes of the SARS-CoV-2 S1 subunit and RBD domain.

We have sold recombinant rabbit S1 and RBD mAbs and licensed some clones to diagnostic companies to develop COVID-19 antigen test kits. Welcome to contact us if you are interested in our rabbit monoclonal antibodies against SARS-CoV-2 Spike protein especially the S1 subunit or RBD (receptor binding domain).

To know more about our rabbit monoclonal antibody development services, please visit:

Rabbit monoclonal antibody development services
Single B cell antibody cloning and sequencing services

In addition to SARS-CoV-2 Spike S1 protein and RBD rabbit monoclonal antibodies, monoclonal antibodies from other species have also been developed and produced:

Recombinant alpaca nanobodies (VHH-Fc) against the SARS-CoV-2 Spike S1 subunit and RBD;
Mouse monoclonal antibodies against the SARS-CoV-2 Spike S1 and RBD;
Recombinant human monoclonal antibodies against the SARS-CoV-2 Spike protein, S1 subunit, and RBD.


The S1 subunit of the SARS-CoV-2 (2019-nCoV) spike (S) glycoprotein plays the most important roles in viral attachment, fusion and entry, and serves as a target for development of virus entry inhibitors, neutralizing antibodies, and vaccines. There are two subunits, S1 and S2, in the SARS-CoV-2 spike (S) glycoprotein. The S1 subunit, the N-terminal 14–685 amino acids of S protein, contains N-terminal domain (NTD), receptor binding domain (RBD), and receptor binding motif (RBM). The SARS-CoV and SARS-CoV-2 S proteins mediate viral entry into host cells by binding to a host receptor, angiotensin-converting enzyme 2 (ACE2), through RBD in the S1 subunit, and then fusing the viral and host membranes through the S2 subunit.

The SARS-CoV-2 S1 subunit especially its RBD has become a popular target of antibodies for diagnostics test and proteins and antibodies for therapeutic drugs. The amino-acid sequence identity is around 74% between the RBDs in the SARS-CoV and SARS-CoV-2 spike proteins, similar to the 77% identity between the whole spike proteins of SARS-CoV and SARS-CoV-2. Such a high degree of sequence similarity raises the possibility that cross-reactive epitopes may exist. Although the SARS-CoV RBD polyclonal antibodies can recognize both viruses, it was reported that only one published RBD monoclonal antibodies neutralizing SARS-CoV bound to SARS-CoV-2 spike RBD. Out of the 28 residues in the epitope of the S1 RBD monoclonal antibody, only 4 residues (86%) in SARS-CoV-2 are different from SARS-CoV. However, the S1 RBD mAb binds to SARS-CoV spike RBD (Kd = 1 nM) with a much higher affinity than to SARS-CoV-2 spike RBD (Kd = 115 nM, or 6.3 nM measured by another lab). Thus, it is important and possible to develop SARS-CoV-2 specific monoclonal antibodies using SARS-CoV-2 Spike protein, its S1 subunit, or RBD with binding and even neutralizing functions.

To check more Syd Labs SARS-CoV-2 (2019-nCoV) Antigen and Antibody Reagents and Discovery Services

Questions and Answers:

Question: Is SARS-CoV-2 spike protein S1 subunit or its RBD a better immunogen for antibody development?
Answer: S1 subunit is better since it is bigger with more potential epitopes possibly better for neutralizing antibody development. Even for RBD, some antibodies binds to RBD but does not block the interaction between RBD and the receptor ACE2.

Question: Do you deliver a cell line like hybridoma?
Answer: No, the rabbit monoclonal antibody sequences (VH and VL) or plasmid DNAs will be delivered. Clients can use them to produce recombinant rabbit monoclonal antibodies in HEK 293 or CHO cells.

Question: What is the advantage of your rabbit monoclonal antibody screening method against other single B cell-based rabbit monoclonal antibody development methods?
Answer: Using the strategy without culturing, one may screen antibodies from hundreds of single B cells after a lot of efforts; however, one may easily screen antibodies from thousands of cultured single B cells.

Question: Can I license the clone sequences after screening?
Answer: If only one client is interested in a clone, he/she can license the clone. If more than one client are interested in the same clone, we prefer to sell purified antibodies.

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