Architect sars cov 2 igg

We assessed SARS-CoV-2 IgG antibodies in all samples using three commercially available assays.
First, chemiluminescence immunoassay (CLIA) technology for the quantitative determination of anti-S1 and anti-S2 specific IgG antibodies to SARS-CoV-2 was used: Diasorin LIAISON SARS-CoV-2 S1/S2 IgG Assay. Antibody levels > 15.0 AU/mL were considered positive and levels between 12.0 and 15.0 AU/mL were considered equivocal.
Second, an ELISA detecting IgG against the S1 domain of the SARS-CoV-2 spike protein, Euroimmun Anti-SARS-CoV-2 ELISA, was used; a ratio < 0.8 was considered negative, 0.8–1.1 equivocal, > 1.1 positive.
Third, chemiluminescent microparticle immunoassay (CMIA) intended for the qualitative detection of IgG antibodies to the nucleocapsid protein of SARS-CoV-2, Abbott Diagnostics ARCHITECT SARS-CoV-2 IgG, was used. This assay relies on an assay-specific calibrator to report a ratio of specimen absorbance to calibrator absorbance. The interpretation of result is determined by an index (S/C) value, which is a ratio over the threshold value. An index (S/C) of < 1.4 was considered negative, ≥ 1.4 was considered positive.

Blood samples were collected once. Enzyme-linked immunosorbent assay (ELISA) was performed using the Architect SARS-CoV-2 IgG and IgG II Quant assay (Abbott-NP, Abbott, Chicago, IL) were used to detect antibody responses against SARS-CoV-2 [14 (link)–16 (link)]. The cutoff value for a positive IgG response was anti-Spike S1 protein IgG (Anti-S) < 50.0 AU/mL and anti-nucleocapsid IgG index (Anti-N) ≥ 1.4 according to the instructions of the manufacturer [14 (link)–16 (link)]. We have proceeded to convert the antibody titer measurements from arbitrary units per milliliter (AU/mL) to WHO’s standard BAU/mL, with BAU/mL being calculated as 0.142 times AU/mL.

Based on the results of antibody testing conducted in the Tokyo metropolitan area [12 ], the antibody-positive rate was predicted to be ≤1%. Therefore, it is important to use highly specific antibodies to reduce the false-positive rate [13 (link)]. In a systematic review of the diagnostic accuracy of antibody tests, the specificity of enzyme-linked immunosorbent assay and chemiluminescent immunoassay was reported to be high [14 (link)]; therefore, we used Elecsys^® Anti-SARS-CoV-2 (Roche Diagnostics), a chemiluminescent immunoassay. According to the manufacturer, the antibody test has a sensitivity of 100% (95% confidence interval [CI]: 88.1–100%) and specificity of 99.81% (95% CI: 99.65–99.91%) [15 ].
To confirm the sensitivity, patients who were admitted to the hospital with COVID-19 confirmed using a positive SARS-CoV-2 PCR test result were tested for antibodies (both Elecsys^® Anti-SARS-CoV-2 and Architect SARS-CoV-2 IgG [Abbott Laboratories Inc.]). All 10 patients with COVID-19 tested positive for anti-SARS-CoV-2 antibodies on both tests.
Additionally, the samples collected in May 2020 were tested for anti-SARS-CoV-2 IgG using Architect SARS-CoV-2 IgG [16 (link)] to check the consistency of the results. Any positive antibody results were confirmed using the Architect SARS-CoV-2 IgG Assay and Cica Immuno-test SARS-CoV-2 IgG [17 ].

The following commercial CE in vitro diagnostics (IVD) marked assays were used to determine the presence of SARS-CoV-2-specific antibodies in serum specimens: Architect SARS-CoV-2 IgG (6R86, Abbott, Illinois, USA) detecting anti-nucleocapsid antibodies and Anti-SARS-CoV-2-ELISA IgG (EI 2606–9601 G, EuroImmun, Lübeck, Germany) recognizing antibodies against the S1 domain of viral spike protein. Assays were performed in accordance with the manufacturers’ instructions by trained laboratory staff on appropriate analyzers and with the specified controls and calibrants, using thresholds for calling positives, indeterminates and negatives set by the manufacturers.

In order to exclude patients with prior SARS-CoV-2 infection, a qualitative chemiluminescence microparticle immunoassay was used for the qualitative detection of IgG antibodies against the SARS-CoV-2 nucleocapsid protein (Architect SARS-CoV-2-IgG, Abbott GmbH, Wiesbaden, Germany).
A quantitative analysis of IgG antibodies directed against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein was performed by chemiluminescence microparticle immunoassay (CMIA) (Architect SARS-CoV-2-IgG II Quant, Abbott GmbH, Wiesbaden, Germany). Vaccine response was considered to be present at a titer of >50 AU/mL (the threshold specified by the manufacturer).