Objective:

To evaluate the performance of the T-SPOT.COVID test to identify SARS-CoV-2 sensitive T cells in participants with SARS-CoV-2 infection.

Methods:

The T-SPOT.COVID test uses interferon-gamma release assay (IGRA) ELISpot methodology to measure T-cell responses to SARS-CoV-2 S1 spike and nucleocapsid peptides. T-SPOT.COVID and anti-N immunoglobulin (Ig)G serology tests were performed on blood from 186 patients with SARS-CoV-2 infection confirmed by nucleic acid amplification test (NAAT) and 100 control group participants.

Results:

Within 2-8 weeks after NAAT-diagnosed SARS-CoV-2 infection, the T-SPOT.COVID test detected 98.4% (63 of 64) of infected participants, while serology anti -N IgG detected 82.8%. In the first 2 weeks after diagnosis, during the activation of the adaptive immune response, there were fewer reactive T-SPOT.COVID responses (75.7%, 28 of 37 participants infected) and far fewer seropositive responses (32.4%).

Response numbers decreased after 8 weeks; however, the T-SPOT.COVID test continued to detect the majority of participants with confirmed infection (83.6%, 56 of 67) and continued to outperform serology (52.2%). T-SPOT.COVID response due to cross-reactive T cells was ruled out by showing that, of the 44 participants in the control group with T cells that responded to 4 human common cold coronavirus peptides, only 1 was reactive with T -SPOT.COVID.

Conclusion:

The T-SPOT.COVID test performed well in detecting SARS-CoV-2 sensitized T cells for many months.

Keywords:

COVID-19; IGRA; SARS-CoV-2; T-SPOT.COVID; interferon-gamma release assay; serology.

The T-SPOT.COVID Test Antigen Mix Optimized for SARS-CoV-2

The T-SPOT.COVID test is a simple blood test intended to help identify people with an adaptive immune response to SARS-CoV-2, specifically the T-cell response. The test uses T-SPOT technology, a modified ELISPOT technology, with an optimized mixture of antigens, based on structural proteins, spike and nucleocapsid (S and N) of SARS-CoV-2, and allows to achieve the maximum amplitude of the immune response measured.

The T-SPOT.COVID test

CE marked for IVD use

  • Tested for evidence of a T-cell mediated immune response to SARS-CoV-2 infection in PCR-positive patients with a negative serology test result
  • The results, complemented by serology results, provide a comprehensive view of an individual’s immune response to SARS-CoV-2
  • Results can be generated quickly, the lab process takes only 2 days

Why partner with Oxford Immunotec?

A leading global diagnostics company with an 18-year history of transforming T cell science into meaningful insights using T-SPOT technology. T-SPOT technology is proven in the diagnosis of TB with more than 20 million tests shipped to more than 50 countries where the T-SPOT is.TB test is approved for clinical use.

Higher positive agreement than a leading serology test

In a study of 135 people, with a prior positive PCR result for SARS-CoV-2 infection, samples were tested with both the T-SPOT.COVID test and a leading serology test.

  • Positive T-cell concordance remained high throughout the duration of the study
  • Positive concordance of serology decreased over time
  • Positive serology concordance was low before 14 days.

Serology alone is not enough

Research shows that T-cell response and antibody immune response independently correlate with protection against SARS-CoV-2. The antibody response represents one half of the immune system and the T cells are the other half. A subsequent analysis of the study cohort assessed overlap between the two testing methods.

How does T-SPOT technology work?

Our T-SPOT.COVID test based on ELISPOT technology is normalized for both cell number and culture conditions. This means that the test standardizes the number of cells and eliminates serum factors that could negatively affect the results, making it the most sensitive and specific test for measuring T cells. A blood sample is collected via phlebotomy from routine and a standard blood collection tube from which a subset of white blood cells, known as peripheral blood mononuclear cells (PBMCs), is isolated.

Cells are washed, counted, and normalized to create a standard cell suspension. A standard number of cells are added to specially designed plates and stimulated with antigens specific to the disease under study. Cells that respond to these antigens release a chemical messenger known as a cytokine. Cytokine antibodies are used to directly capture the cytokine as it is released from cells.

A secondary labelled antibody is added and binds to the captured cytokine. A detection reagent is added and reacts with the secondary labelled antibody. This reaction produces spots, which are an imprint of where the cytokine was released. Then the points are listed.

What does a positive T-SPOT? COVID test result mean?

A positive test result means that the patient has T cells that react to the SARS-CoV-2-specific peptides used in the T-SPOT.COVID test. It is very likely that they have been exposed to the SARS-CoV-2 virus.

What does a negative test result mean?

A negative test result means that the patient does not have T cells reactive to the SARS-CoV-2-specific peptides used in the test. Therefore, it is unlikely that they were exposed to the SARS-CoV-2 virus.

What regulatory approval does the T-SPOT.COVID test have?

The T-SPOT.COVID test is CE marked and has been submitted to the FDA for emergency use authorization.

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