SARS-CoV-2 Inhibitor Screening Kit

Designed for identifying and characterizing molecules that block SARS-CoV-2 viral entry, this screening kit from STEMCELL Technologies measures inhibitors of the interaction between the viral Spike (S) protein and the human angiotensin-converting enzyme 2 (ACE2) receptor. The S protein is a type I transmembrane glycoprotein present on the surface of coronaviruses that mediates host cell entry by binding ACE2, a receptor expressed on intestinal and respiratory epithelia in humans.

The assay is based on a competitive ELISA method using a flat-bottom 96-well plate (6 strips × 16 wells) coated with recombinant SARS-CoV-2 Spike protein receptor-binding domain (RBD). Test inhibitors are mixed with biotinylated recombinant human ACE2 and added to the coated wells. Captured ACE2 is detected using streptavidin-horseradish peroxidase (SA-HRP) and 3,3',5,5'-tetramethylbenzidine (TMB) substrate, producing a coloured product with intensity proportional to ACE2 binding activity. More effective inhibitors compete with biotinylated ACE2 for binding to the S protein, producing reduced signal. An anti-human ACE2 blocking antibody (clone AC384) is included as a positive control. Plates are read at a wavelength of 450 nm.

The kit can also be performed in a reverse configuration, with biotinylated recombinant ACE2 coating the plate and recombinant S protein as the binding partner, detected using HRP-conjugated anti-human IgG antibody. All kit components are stable until the expiry date on the label and should be stored at 2-8°C upon receipt, with opened components stored at 2-8°C and used within one month.