Anti sars cov 2 quantivac elisa igg

Blood samples were collected upon the admission for the booster shot and also on day 28±5 after it. Upon serum isolation, assessment of the generated antibodies was investigated with titers of Anti-SARS-CoV-2 Quantivac ELISA (IgG) (Euroimmun, Lübeck, Germany) and SARS-CoV-2 Neutralizing Ab (Pishtazteb, Iran).

Blood sera samples were collected before booster administration and 28, 60, 90, and 180 days after it. The levels of antispike IgG antibody, antiRBD IgG, and neutralizing antibody were measured using Anti-SARS-CoV-2 Quantivac ELISA (IgG) (Euroimmun, Lübeck, Germany), antiRBD IgG (Idealtashkhis, Tehran, Iran), and SARS-CoV-2 Neutralizing Ab (Pishtazteb, Iran), respectively. Thresholds of ≥2.5, 5, and 11 IU/mL were considered positive for SARS-CoV-2 Neutralizing Ab, antiRBD SARS-CoV-2, and antispike SARS-CoV-2 IgG, respectively. The antibody concentration above the threshold was repeated by diluting the samples with diluent solution.

Anti-SARS-CoV-2 QuantiVac ELISA IgG (Euroimmun Medizinische Labordiagnostika, Lübeck, Germany) was used for quantification of human antibodies of the immunoglobulin class IgG against the S1 domain of the SARS-CoV-2 spike protein in the sera of investigated individuals. Antibody titer was measured from the same blood sample to compare humoral and cellular immunity.
All values below the cut-off value of 200 mIU/mL for IFN-γ concentration and 35.2 IU/mL for antibody concentration were reported as negative results [15 (link)].

As a primary screening system, a quantitative ELISA for anti-SARS-CoV-2 spike protein 1 (S1) immunoglobulin G (IgG) will be used. We will use the CE certified version of the Anti-SARS-CoV-2-QuantiVac-ELISA (IgG) from Euroimmun, Lübeck, Germany. A semi-quantitative ELISA detecting anti-SARS-COV-2 S1 immunoglobulin A (IgA) will be performed in a subset of samples. In order to discriminate IgG specific for the spike regions S1, S2, and RBD multiplex analyses for IgG will be performed with plasma samples (1:200 dilutions) using the Luminex-based multiplex analyses (MiIliplex HC19SERG1-85). For Interferon Gamma Release Assays (IGRA) the Quant-T-Cell SARS-CoV-2 (Euroimmun, Lübeck, Germany) kits will be used.
Furthermore, influenza A/B IgG will be measured in selected frozen samples (i.e. those negative to anti-SARS-CoV-2 IgG). A suitable testing system will be selected when all samples have been acquired.
All remaining plasma samples will be available for additional research questions, in case novel serology testing systems (e.g. for assessing viral entry inhibition) or experimental tools evaluating neutralization of novel SARS-CoV-2 variants of concern become available.

313 serum samples from 155 individuals with previous SARS-CoV-2 infection (with or without SARS-CoV-2 vaccination) were analyzed by two commercially available assays according to the instructions of the manufacturer (anti-SARS-CoV-2-QuantiVac-ELISA (IgG), Euroimmun, Lübeck, Germany and Elecsys Anti-SARS-CoV-2 S, Roche, Mannheim, Germany). For individuals who have been measured several times, the sera were obtained from independent plasma donations performed at different dates. Samples were collected after written informed consent was obtained from convalescent plasma donors (22 (link)) and vaccinated individuals. The studies were approved by the Ethical Committee of University of Ulm and Ethical Committee II, Heidelberg University (392/20, 488/20, 56/21 and 41/22).

Antibodies against S1 and NCP were measured using the Anti-SARS-CoV-2 QuantiVac ELISA IgG, Anti-SARS-CoV-2 ELISA IgA and Anti-SARS-CoV-2 NCP ELISA IgG (EUROIMMUN Medizinische Labordiagnostika AG, Lübeck, Germany). Assays were performed and evaluated according to the manufacturer’s instructions. For anti-S1 IgG, results <25.6 binding antibody units (BAU)/mL were considered negative, ≥25.6 to <35.2 borderline, and ≥35.2 positive. For anti-S1 IgA and anti-NCP IgG, ratios <0.8 considered negative, ≥0.8 to <1.1 borderline, and ≥1.1 positive.

Before the COVID-19 vaccination, we determined the prevalence of SARS-CoV-2 infection using semi-quantitative anti-SARS-CoV-2 S IgG ELISA (EuroImmun GmbH, Lübeck, Germany). In addition, positive ELISA results were confirmed by quantitative anti-SARS-CoV-2 IgG immunoblots (Polycheck; Biocheck GmbH, Münster, Germany), which detected the anti-SARS-CoV-2 spike (S) protein and nucleocapsid protein (NCP) antibodies. After COVID-19 vaccination, a quantitative analysis of anti-SARS-CoV-2 S antibody levels was performed using anti-SARS-CoV-2 QuantiVac ELISA IgG (EuroImmun GmbH) according to the manufacturer’s instructions. Moreover, to analyze the SARS-CoV-2 seroprevalence after vaccination we used the anti-SARS-CoV-2 NCP IgG ELISA (EuroImmun GmbH), which detects anti-SARS-CoV-2 NCP antibodies generated only after natural infection and not produced as a consequence of BNT126b2 mRNA COVID-19 vaccination. The semiquantitative anti-SARS-CoV-2 NCP ELISA results were further confirmed by the quantitative anti-SARS-CoV-2 IgG immunoblots (Polycheck, Biocheck GmbH).