COVID-19 (SARS-CoV-2) Antibody Test
Serological antibody tests for COVID-19 are used to detect the presence of antibodies against the SARS-CoV-2 virus. A positive result may indicate whether an individual has been exposed to, and mounted an immune response to, the virus. Specific and sensitive antibody tests are needed to provide insights to inform patient treatment and aid in population surveillance.
The Lumit™ Dx SARS-CoV-2 Immunoassay uses a fragment of the spike (S) protein chemically labeled with the small and large subunits of NanoBiT® Luciferase to detect antibodies. Bioluminescent antibody detection offers a simple workflow and lower background signal noise than traditional ELISA antibody tests.
Introduction to COVID-19 Antibody Tests
Accurate tests for detecting antibodies to the SARS-CoV-2 virus is crucial both for determining individual exposure and for population screening and surveillance. The presence of antibodies in a serum or plasma sample can be indicative of exposure, signaling that the individual has mounted an immune response to the virus. In addition to informing about individual exposure, antibody tests can be used by public health officials to better estimate prevalence of the SARS-CoV-2 virus.
Several antibody detection methods use an antigen to detect antibodies. The spike (S) glycoprotein of the SARS-CoV-2 virus binds to cellular ACE2 receptors, which allow the virus to infect the cell. This makes the glycoprotein a primary target of neutralizing antibodies and a good antigen choice for detecting antibodies.
ELISAs (Enzyme Linked Immunosorbent Assays) are a typical antibody test, or immunoassay method, used to detect SARS-CoV-2 antibodies. This method uses an antigen, such as a portion of the nucleocapsid (N) protein or other SARS-CoV-2-specific proteins, attached to a plate or solid surface. Antibodies from the sample bind to the antigen. A second antibody linked to an enzyme is used to detect the bound antibodies via a colorimetric signal. This approach is relatively easy to use but can be time consuming. It requires multiple wash and incubation steps, suffers from background signal noise and may produce variable results.
The Lumit™ Dx Immunoassay technology offers in-solution bioluminescent antibody detection without requiring wash steps or specialized plates. The assay uses a SARS-CoV-2 spike (S) protein fragment chemically labeled with the small and large subunits of NanoBiT® Luciferase (SmBiT and LgBiT, respectively). In the presence of SARS-CoV-2 antibodies, the two labeled proteins come into close proximity, allowing the two NanoBiT® subunits to form an active enzyme. Once a detection reagent is added, a bright luminescence signal is generated.