Anti-SARS-CoV-2 Neutralizing Antibody (NtAb) ELISA Kit

Catalog No.: BEK1265

Size: 96T

Storage and Expiration: Store at 2-8℃ for 6 months.

1. Store Positive Control, Negative Control and HRP conjugated S-RBD antibody at -20℃.
2. It is recommended to use the kit within 1 month once open.

Application: For qualitative detection of any antibodies that neutralize the interaction of SARS-CoV-2 Spike RBD-ACE2 in serum, plasma.

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, or 2019-nCoV) is an enveloped non-segmented positive-sense RNA virus. It is the cause of coronavirus disease 2019 (COVID-19), which is contagious in humans. SARS-CoV-2 has several structural proteins including spike (S), envelope (E),membrane (M) and nucleocapsid (N). The spike protein (S) contains a receptor binding domain (RBD), which is responsible for recognizing the cell surface receptor, angiotensin converting enzyme-2 (ACE2). It is found that the RBD of the SARS-CoV-2 S protein strongly interacts with the human ACE2 receptor leading to endocytosis into the host cells of the deep lung and viral replication. Infection with the SARS-CoV-2 initiates an immune response, which includes the production of antibodies in the blood. The secreted antibodies provide protection against future infections from viruses, because they remain in the circulatory system for months to years after infection and will bind quickly and strongly to the pathogen to block cellular infiltration and replication. These antibodies are named neutralizing antibodies. 

This kit can detect circulating neutralizing antibodies against SARS-CoV-2 that block the interaction between the receptor binding domain of the viral spike glycoprotein (RBD) with the ACE2 cell surface receptor. The detection is not limited by both species and antibody isotypes.

Principle of the Assay  

The kit is based on the competitive ELISA, it is a blocking ELISA detection tool, which mimics the virus neutralization process. The kit contains two key components: HRP conjugated recombinant SARS-CoV-2 Spike RBD fragment protein (HRP-SRBD) and the human ACE2 receptor protein (hACE2). The protein-protein interactions between HRP-SRBD and hACE2 can be blocked by neutralizing antibodies against SARS-CoV-2 Spike RBD. Incubate the samples and controls with HRP-SRBD to make the combination of the neutralization antibodies with HRP-SRBD. Then, add the mixture to the hACE2 pre-coated plate. The unbound HRP-SRBD as well as any HRP-SRBD bound to non-neutralizing antibody will be captured on the plate, while the neutralizing antibodies-HRP-SRBD complexes remain in the supernatant and were washed away with  wash buffer. TMB substrates were used to visualize HRP enzymatic reaction. TMB was catalyzed by HRP to produce a blue color product that changed into yellow after adding acidic stop solution. The density of yellow is inverse to the Anti-SARS-CoV-2 Neutralizing Antibody amount of sample captured in plate. Read the O.D. absorbance at 450nm in a microplate reader, and then the concentration of Anti-SARS-CoV-2 Neutralizing Antibody can be calculated.