Researchers at Cayman have developed a SARS-CoV-2 Neutralizing Antibody Detection ELISA Kit to enable semi-quantitative identification of neutralizing antibodies in human plasma or serum for the SARS-CoV-2 virus that causes COVID-19. Starting approximately 4-10 days after symptom onset, SARS-CoV-2 infection can lead to the production of neutralizing antibodies that bind to the viral spike protein receptor binding domain (RBD) on the S1 subunit and prevent its interaction with the human ACE2 receptor, preventing further viral entry and infection. Investigators can utilize this technology to investigate antibody response and recovery from infection.
“We designed the ELISA to detect any antibodies—independent of isotype—that neutralize the spike-ACE2 interaction,” said Daniel Tew, Manager of ELISA Research and Development at Cayman. “Any SARS-CoV-2 neutralizing antibodies present will interfere with the interaction between SARS-CoV-2 spike RBD and ACE2.”
The ELISA includes a SARS-CoV-2 neutralizing antibody as a standard that was tested to ensure its interference with the ACE2 protein for binding sites on the SARS-CoV-2 spike S1 RBD. The assay can be completed in under 4 hours using a plate-based, colorimetric (450 nm) readout. The assay has a range of 7.81-1,000 ng/ml with a midpoint of approximately 107 ng/ml (50% B/B 0 ) and a sensitivity (80% B/B 0 ) of approximately 41 ng/ml. Validation of the kit was performed using plasma from volunteers that tested positive in a PCR test for COVID-19.
“The detection of neutralizing antibodies to SARS-CoV-2 is important in evaluating the lifetime and efficacy of specific antibodies in the infected individual,” said Dr. María Inés Morano, Senior Director of Discovery Research and Development at Cayman. “This ELISA offers the opportunity to investigate SARS-CoV-2 neutralizing antibodies present in convalescent plasma as well as those raised against the SARS-CoV-2 spike glycoprotein in vitro.”