AffinityImmuno Inc.’s SARS-CoV-2 spike protein ligand binding assay allows rapid quantification of COVID-19 neutralizing antibodies in serum and plasma by measuring reduction in the binding of viral spike protein with its receptor ACE2. This assay allows rapid analysis of convalescent plasma, antibody-based therapeutics, vaccine leads, and immune response to the virus. This serological platform was designed as a tool to begin understanding the correlation between neutralizing antibody level and protective immunity in recovered SARS-CoV-2.
The World Health Organization has recently cautioned that positive results from antibody tests (IgM and IgG antibody tests) do not equal protective immunity owing to the fact that most antibodies in an immune response are not neutralizing and in fact may enhance infection. Current available antibody tests are for detection of binding antibodies, and do not differentiate neutralizing antibodies from total antibodies. The presence of neutralizing antibodies may or may not correlate with protection in SARS-CoV-2 serum, although neutralizing antibody levels is a good indicator of protective immunity in many other viral models.