SARS-CoV-2 Spike RBD Monoclonal Antibody

Human IgG Monoclonal Antibody.The monoclonal SARS-CoV-2 (2019-nCoV) spike antibody (S protein antibody, spike S1 antibody) was produced in mammalian cells.Specificity/Sensitivity: The monoclonal SARS-CoV-2 (2019-nCoV) spike RBD antibody binds to SARS-CoV-2 and SARS-CoV spike RBD, S protein, and S1 subunit.Applications: ELISA 1:10000, Flow Cytometry 1:500. It might be used as the human IgG antibody positive control for serological assays to detect SARS-CoV and SARS-CoV-2 infection.Form of Antibody: 1 mg/ml in PBS, pH 7.4.Clone: 25G1.Isotype: hIgG1, H+L.Purity: >95% by SDS-PAGE under reducing conditions.Shipping: The monoclonal SARS-CoV-2 spike RBD antibody is shipped with ice pack. Upon receipt, store it immediately at the temperature recommended below.Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.12 months from date of receipt, -20 to -70°C as supplied.

1 month from date of receipt, 2 to 8°C as supplied.

Background

The receptor binding domain (RBD) in the S1 subunit of the SARS-CoV-2 (2019-nCoV) spike (S) glycoprotein plays the most important roles in viral attachment, fusion and entry. 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 the receptor-binding domain (RBD) in the S1 subunit, and then fusing the viral and host membranes through the S2 subunit. The ACE2-binding affinity of the Spike RBD of SARS-CoV-2 is 10- to 20-fold higher than that of SARS-CoV.

The SARS-CoV-2 S protein, especially its S1 subunit and 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 S proteins, similar to the 77% identity between the whole S 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, only one out of a few published RBD monoclonal antibodies neutralizing SARS-CoV binds to SARS-CoV-2 spike RBD. Out of the 28 residues in the epitope of the S1 RBD monoclonal antibody, only 4 residues (14%) in SARS-CoV-2 S1 RBD are different from those in SARS-CoV S1 RBD. 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). It remains unreported that the S1 RBD neutralizing monoclonal antibody from a recovered SARS patient also behaves as a neutralizing antibody of SARS-CoV-2.