SARS-CoV-2 IGRA - INF-Gamma

Interferon gamma (IFN-γ) is a cytokine critical to both innate and adaptive immunity, and functions as the primary activator of macrophages, in addition to stimulating natural killer cells and neutrophils. T lymphocytes from most persons that have been infected with SARS-CoV-2 will release interferon gamma (IFN-γ) when mixed with antigens derived from SARS-CoV-2. WANTAI SARS-CoV-2 IGRA is an enzyme-linked immunosorbent assay for quantitative detection of Interferon Gamma (IFN-γ) that responds to in-vitro stimulation by spike protein of SARS-CoV-2 in human whole blood. It is intended for use as an aid in the diagnosis of specific T cellular immune response of SARS-CoV-2 spike protein after vaccination or infection. This kit cannot be used as the only basis for clinical diagnosis. PRINCIPLE OF THE TEST This kit uses the principle of IGRA combined with enzyme linked immunosorbent assay (ELISA) to measure specific antigen mediated immune response strength. Specific T lymphocytes of SARS-CoV-2 after vaccination is stimulated and proliferated by SARS-CoV-2 specific antigen (spike protein), then release IFN-γ. Polystyrene microwell strips are pre-coated with mouse anti-human IFN-γ IgG monoclonal antibody. During the first incubation step, the IFN-γ, if present, will be bound to the solid phase pre-coated anti-IFN-γ antibody, then anti-IFN-γ antibody conjugated to horseradish peroxidase (HRP) are added. During the second incubation step, these HRP-conjugated antibodies will be bound to any complex previously formed and the unbound HRP-conjugate or unbound proteins are then removed by washing. Chromogen solutions containing Tetramethyl benzidine (TMB) and urea peroxide are added to the wells. In presence of immunocomplex, the colorless Chromogens are hydrolyzed by the bound HRP conjugate to a blue colored product. The blue color turns yellow after stopping the reaction with sulfuric acid. Wells containing no IFN-γ remain colorless. The amount of color intensity can be measured and is proportional to the amount of IFN-γ captured in the wells, and to the specimen respectively. The concentration of IFN-γ can be calculated by standard concentration and absorbance value (A value) to determine the existence of T cellular immune response to SARS-CoV-2. MATERIALS AND REAGENTS Microwell plate Background control culture tube (N) Testing culture tube (T) Positive control culture tube (P) Standard HRP - Conugate Speciment diluent Standard diluent Wash buffer Chromogen solution A Chromogen solution B Stop solution Plastic sealing bag Package insert PERFORMANCE A group of 129 vaccinated individuals were tested with this kit, 14 tested negative and 115 tested positive, which calculates in sensitivity of 89.15%. In a group of 91 non-vaccinated and non-infected individuals, 90 tested negative, 1 tested positive (false positive), which calculates in specificity of 98.90%. The first CE-IVD certified SARS-CoV-2 test for quantitative measurement of interferon gamma levels by the ELISA method