Coronavirus and anti-coronavirus antibody detection in blood by ELISA.

At the end of July 2020, more than 300 antibody-based tests were available.

Most of them are based on the Enzyme-Linked Immunosorbent Assay (ELISA) principle. ELISA is a high sensitivity and throughput test typically performed in a multi-well plate coated with antigen or antibodies. Detection is versatile as it can be colorimetric, fluorescent, chemiluminescent, or electrochemical.

Immunoassays can be used for:

Antigen tests: allowing the detection of the virus. 

Serological tests: allowing the detection of host-derived antibodies against SARS-CoV-2 (3).

Antigen tests

Effective antigen-based tests could be an alternative to molecular testing. Viral antigens can be detected when the virus is actively replicating.

Antigen tests are rapid and highly specific but still may lack sensitivity. Thus, they can be used as a fast triage reducing the need for a molecular confirmation (3).

To improve diagnostic accuracy, one needs to develop and synthesize highly immunogenic, high-affinity viral antigens (3). Nowadays, several rapid test kits are under development or already available, i.e. using monoclonal antibodies against N protein of SARS-CoV-2(8).

Even if qPCR testing remains the method of choice for COVID-19 diagnostic, antigen testing is considered a good alternative to prevent the shortage of qPCR Reagents.

Principle

  1. Coating
    Antibodies against SARS-CoV-2 protein are coated on a plate.

  2. Biological samples from a patient potentially containing SARS-CoV-2 are added to the plate.

  3. Recognition
    Labeled antibodies recognizing SARS-CoV-2-derived antigens are added to detect the presence of the virus in the sample.

  4. Signal detection

Serological tests

Based on data on SARS-CoV, among the four structural proteins, Spike and Nucleocapsid proteins are suggested to be the most immunogenic (6,7). More precisely the S1 subunit of SARS-CoV-2 Spike protein is considered the most suitable antigen because it has the least overlap with other coronaviruses. (6)

Principle

  1. Coating
    1. Viral proteins or peptides are coated on a plate.
    2. Secondary antibodies recognizing human IgG or IgM are coated on a plate.

  2. Blood, plasma or serum, or potentially other biological fluids (like saliva) from a patient potentially containing anti-SARS-CoV-2 antibodies is added to the plate.

  3. Recognition
    1. Labeled secondary antibodies recognizing human IgG or IgM are added to detect the presence of anti-SARS-CoV-2 antibodies
    2. Labeled proteins or peptides are added to detect the presence of anti-SARS-CoV-2 antibodies

  4. Signal detection and antibody titer determination

Choose your weapon

We have various tools to help you in your serological test development

We have developed catalog peptide libraries derived from spike protein.
We also offer custom peptide library synthesis upon request.

Catalog SARS-CoV-2 peptides libraries Specifications
Custom peptides libraries Learn more

Besides ready-to-use catalog peptides from SARS-CoV-2 proteins including critical peptide domains/regions or peptide substrates, we can synthesize custom peptides from simple to highly complex sequences.

We also offer custom manufacturing of Critical Raw Material (CRM) peptides for demanding applications.

Catalog SARS-CoV-2 peptides Learn more
Custom peptide synthesis Learn more
Critical raw material peptides Learn more

We are producing recombinant proteins like Nucleocapsid protein, Spike protein or a domain thereof, or ACE2 receptor variants, do not hesitate to contact us. Some of them are already available!

Contact us

We are ready-to-start immunization programs targeting Spike glycoprotein from SARS-CoV-2 and other antigens.

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SARS-CoV-2 related subjects

References


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