Elecsys® IGRA SARS-CoV-2
Immunoassay for the qualitative detection of T cell-mediated immune response to SARS-CoV-2
Elecsys® IGRA SARS-CoV-2 test was developed as an aid in identifying individuals with an adaptive T cell response to SARS-CoV-2, indicative of past exposure to the virus or COVID-19 vaccination. By that, it provides the physicians valuable information on the T cell responses of the patient, enabling them to make better-informed decisions for patient care.
Together with other diagnostic and serological assays, Elecsys® IGRA SARS-CoV-2 represents a complementary tool that allows physicians to have a comprehensive picture of the immune status of patients.
Elecsys® IGRA SARS-CoV-2 assay characteristics
The Elecsys® IGRA SARS-CoV-2 test combines the cobas® IGRA SARS-CoV-2 Tubes for in vitro T cell stimulation and an automated electrochemiluminescence immunoassay (“ECLIA”) for interferon gamma measurement, to qualitatively detect T cell-mediated immune response to SARS-CoV-2 in human whole blood. Using 189 different SARS-CoV-2 antigens with a broad coverage of the viral genome and host HLA subtypes, the assay is designed for robustness against viral variants and population diversity.
* Resulting after centrifugation of whole blood after T cell stimulation. ** In plasma samples containing IFN-γ (~0.4 - 90 IU/mL)
** on the cobas e 411 analyzer and the cobas e 601 / 602 modules; *** on the cobas e 801 and cobas e 402 analytical units
Elecsys® IGRA SARS-CoV-2 (Mat. No. 09542477190, 09542485190) method sheets, V1 2022-06.
Elecsys® IGRA SARS-CoV-2 test principle
The Elecsys® IGRA SARS‐CoV‐2 test includes two major steps:
Step 1: ex-vivo / in vitro stimulation of patient T cells with pathogen specific peptides to generate production of interferon gamma indicating a previous contact of the patient with the pathogen - this phase takes place in the cobas® IGRA SARS-CoV-2 Tubes filled with patient whole blood.
Step 2: interferon gamma read out in the plasma extracted from the cobas® IGRA SARS-CoV-2 Tubes after incubation and centrifugation. Such read out will be performed on the cobas platforms with the Elecsys® IGRA SARS-CoV-2 immunoassay.
Elecsys® IGRA SARS-CoV-2
A stimulation phase using SARS-CoV-2 antigens in the cobas® IGRA SARS-CoV-2 tubes
An automated ECLIA IFN-γ readout to qualitatively detect in vitro the patient T cell-mediated immune response to SARS-CoV-2
| Process | T cells in sample are stimulated by SARS-CoV-2 specific peptides. Activated SARS-CoV-2 specific T cells release IFN-γ as a result. | IFN-γ levels are measured and result from the different tubes are combined for the final interpretation, so that the presence of IFN-γ released by SARS-CoV-2 specific cells is determined. |
| Sample | Whole blood (heparinized) | Plasma |
| Incubation Time | 16–24h | 18min |
| Specific for SARS-CoV-2 | Yes | No |
| Manufacturer | LG Chem (3rd party) | Roche |
The Elecsys® IGRA SARS-CoV-2 solution comprises two types of reagents:
- cobas® IGRA SARS-CoV-2 Tubes
- Elecsys® IGRA SARS-CoV-2 immunoassay
T cell collection tubes - Combining the results of 3 individual tubes per patient
Positive control (PC) Tube
Confirmation of sample quality (T cell fitness and stimulation potential)
- Tube coated with mitogen (generic, non-pathogen specific T cell activator)
- Value above a minimum threshold
Negative control (NC) tube
Determination of baseline IFN-γ levels in blood
- No activating components coated inside tube
- Value below a maximum threshold
Antigen (Ag) Tube
Determination of IFN-γ released upon stimulation with SARS-CoV-2 peptides
- Ag test tube coated with SARS-CoV-2 unique peptides (≈ 200)
- Only T cells that recognize and bind to the specific SARS-CoV-2 viral antigens (reactive T cells) will secrete IFN-γ
- No specific threshold
The Elecsys® IGRA SARS-CoV-2 immunoassay is a ready-to-use reagent pack for interferon gamma read-out. The module is calibrated and controlled with a negative and positive calibrator and control, respectively. The PreciControl Interferon Gamma (PC1: negative; PC2: IFN Gamma positive) is launched together with the Elecsys® IGRA SARS-CoV-2 immunoassay.