<< Back to SARS-CoV-2 Home Page

SARS-CoV-2 Overview & Product Data

Antibodies, Assays & Recombinant Proteins Developed by Active Motif

COVID-19 is one of the biggest public health issues in history and presents a unique challenge to the scientific research community – to develop reagents, diagnostics, and therapeutics more quickly than has ever been done.

Active Motif was one of the first companies to be involved in a key collaboration that led to the first cloning, expression, and characterization of recombinant human antibodies from patients who were infected with SARS-CoV-2, mounted an immune response, and recovered. Many of these recombinant antibodies are now available for commercial and research purposes. We also offer multiple recombinant SARS-CoV-2 proteins, including various formats of the SARS-CoV-2 Spike S1 protein, as well as many of the SARS-CoV-2 nonstructural proteins. We have additionally utilized these recombinant antibodies and proteins to create a SARS-CoV-2 Spike S1 protein ELISA.

Recombinant SARS-CoV-2 Antibodies

In partnership with our collaborators at Fudan University, Active Motif scientists successfully performed single-cell analysis of B cells from patients who recovered from COVID-19. Cells were cloned and their antibody genes were expressed, purified, and characterized to create recombinant human antibodies. Many of these have already been published and each is available in up to gram quantities.

Characterization of recombinant COVID-19 antibodies. Several assays were performed to characterize the recombinant human COVID-19 antibodies. The data shown here are from one representative recombinant antibody clone AM001414, Cat. No. 91361.
A.) SARS-CoV-2 Spike protein (Receptor Binding Domain, RBD) binding assay with recombinant human COVID-19 antibodies. SARS-CoV-2 Spike RBD was coated onto microtiter plates and then incubated with the indicated amount of a recombinant human COVID-19 antibody. Bound antibodies were detected with anti-human antibodies conjugated to horse radish peroxidase (HRP) and the resulting absorbance was measured at 450 nm after adding the HRP substrate. The recombinant COVID-19 antibody bound the Spike protein with high affinity. The EC50 value is indicated. B.) Inhibition of COVID-19 Spike RBD/angiotensin converting enzyme-2 (ACE2) interactions by recombinant human COVID-19 antibodies. Using a similar plate-based assay as described in A.), binding of a constant quantity of recombinant ACE2 (His-tagged) in the presence of increasing concentrations of a recombinant human COVID-19 antibody was performed. The recombinant COVID-19 antibody inhibited the interaction between the SARS-CoV-2 Spike protein and ACE2. Bound ACE2 was detected using anti-His Tag-HRP antibody. The IC50 value is indicated. C.) COVID-19 antibodies are neutralizing antibodies and can inhibit infection. Cell-based infection assays using A549 lung epithelial cell line expressing the ACE2 receptor and pseudotyped SARS-CoV-2 virus bearing the S1 spike protein show strong inhibition of viral infection by the recombinant human COVID-19 antibody. The IC50 value is indicated.

SARS-CoV-2 Recombinant Antibody Reactivity with Viral Variants

SARS-CoV-2 Antibody Binding Assay (EC50 Determination)
SARS-CoV-2 recombinant proteins were coated onto microtiter plates and then incubated with the indicated amount of SARS-CoV-2 Spike Antibody (AM002414, Cat. No. 91349). Bound antibody was detected with anti-human IgG conjugated to horse radish peroxidase (HRP) and the resulting absorbance was measured at 450 nm after adding HRP substrate. The EC50 value is indicated, and is the concentration of antibody at 50% of saturation. A summary of Active Motif antibody clones tested for reactivity with viral variants, as well as Spike S1 and Receptor Binding Domain proteins (RBD) is shown below.

SARS-CoV-2 Recombinant Antibodies - Human Ig

AbFlex^® SARS-CoV-2 Recombinant Antibodies - Mouse Ig

Recombinant SARS-CoV-2 Spike S1 Protein ELISA

As the SARS-CoV-2 Spike S1 protein is displayed on the surface of the viral particles, antibodies that bind very specifically and with high affinity to the S1 protein can be used in immunological assays like ELISAs to detect the presence of the virus in biological samples. Each S protein contains two subunits, S1 and S2, with the S1 subunit mainly comprised of the receptor-binding domain (RBD). It is the RBD which is responsible for recognizing the cell surface receptor ACE2.

The SARS-CoV-2 Spike S1 Protein ELISA Kit is designed for the detection of SARS-CoV-2 Spike S1 RBD in a convenient 96-stripwell plate, enabling you to simultaneously process up to 96 samples in a single experiment. For added convenience and a more quantitative interpretation of the results, the kit also includes recombinant Spike S1 RBD which enables you to build a reference standard curve.

SARS-CoV-2 Spike S1 Protein ELISA Kit Highlights:

• Pre-coated wells for faster time-to-result
• Designed for high-throughput use in a 96-well format
• Validated to detect Spike S1 protein in human saliva and plasma samples

More Info

SARS-CoV-2 Spike S1 Protein ELISA Overview: The kit is based on the sandwich enzyme immunoassay technique, using pre-coated well strips with recombinant SARS-CoV-2 Spike S1 antibody. Both recombinant SARS-CoV-2 Spike S1 protein standards and your samples are added to the pre-coated wells. Spike S1 present in the sample(s) is captured by the antibody. A biotinylated SARS-CoV-2 detection antibody is then added, producing the antibody-antigen-antibody “sandwich” immunocomplex. Streptavidin-horseradish peroxidase (HRP) conjugate is then added, followed by the developing solution to enable a sensitive colorimetric readout that is easily quantified by spectrophotometry.

SARS-CoV-2 Spike S1 Protein ELISA Kit – validated for biological samples including saliva and plasma.​

Recombinant SARS-CoV-2 Spike S1 protein generates reliable, consistent standard curves.

Raw absorbance (450 nm) was plotted versus concentration of the SARS-CoV-2 Spike S1 (RBD) Protein Standard. The data shown are an average of four independent experiments. Bars represent standard deviation. The development time was 5 minutes. The curve is a 5-Parameter Logistic (5PL) regression fit to the data determined using GraphPad Prism 8 software.

SARS-CoV-2 Spike S1 Protein ELISA Kit Info

Recombinant SARS-CoV-2 Proteins

Active Motif manufactures our own high-quality recombinant proteins, including SARS-CoV-2 spike S1 proteins, and a number of SARS-CoV-2 nonstructural proteins (NSPs). Each of these proteins is available in up to 1 mg quantities that are in stock and ready to ship. Contact us to inquire about bulk orders.

Recombinant SARS-CoV-2 Spike S1 protein for Antibody Binding and ACE2 Competition Assays
A) SARS-CoV-2 Spike Antibody (clone AM001414) competes with ACE2 receptor for RBD binding. SARS-CoV-2 Spike Antibody (clone AM001414) was serially diluted in the presence of 100 ng/mL biotinylated ACE2 receptor, then added to wells coated with 1 µg/mL RBD, aa319-541 for 30 min. Streptavidin-HRP was then added to detect bound ACE2 receptor. B) SARS-CoV-2 Spike Antibody (clone AM001414) blocks ACE2 receptor from binding to RBD. Serial dilutions of SARS-CoV-2 Spike Antibody (clone AM001414) was added to wells coated with 1 µg/mL RBD, aa319-541. 100 ng/mL biotinylated ACE2 receptor was then added for 30 min, followed by Streptavidin-HRP to detect bound ACE2 receptor.