Evaluation of a Novel Multiplex Platform for Simultaneous Detection of IgG Antibodies Against the 4 Main SARS-CoV-2 Antigens

• Published in: The journal of applied laboratory medicine 2022-05, Vol.7 (3), p.698-710
• Main Authors: Nandakumar, Vijayalakshmi, Profaizer, Tracie, Lozier, Bucky K, Elgort, Marc G, Rychert, Jenna, Slev, Patricia R, Delgado, Julio C
• Format: Article
• Language: English
• Subjects: Antibodies, Viral; COVID-19 - diagnosis; COVID-19 Serological Testing; Humans; Immunoglobulin G; SARS-CoV-2; Sensitivity and Specificity
• ISSN: 2576-9456; 2475-7241
• DOI: 10.1093/jalm/jfab161

Numerous serology assays are available for detection of SARS-CoV-2 antibodies but are limited in that only 1 or 2 target antigen(s) can be tested at a time. Here, we describe a novel multiplex assay that simultaneously detects and quantifies IgG antibodies to SARS-CoV-2 antigens, spike (S), nucleocapsid (N), receptor-binding domain (RBD), and N-terminal domain (NTD) in a single well. Sensitivity was determined using samples (n = 124) from confirmed SARS-CoV-2 RT-PCR positive individuals. Prepandemic (n = 100) and non-COVID respiratory infection positive samples (n = 100) were used to evaluate specificity. Samples were analyzed using COVID-19 IgG multiplex serology assay from Meso Scale Discovery (MSD) and using commercial platforms from Abbott, EUROIMMUN, and Siemens. At >14 days post-PCR, MSD assay displayed >98.0% sensitivity [S 100% (95% CI 98.0%-100.0%); N 98.0% (95% CI 97.2%-98.9%); RBD 94.1% (95% CI 92.6%-95.6%); NTD 98.0% (95% CI, 97.2%-98.9%)] and 99% specificity (95% CI 99.3%-99.7%) for antibodies to all 4 antigens. Parallel assessment of antibodies to more than 1 antigen improved the sensitivity to 100% (95% CI 98.0%-100.0%) while maintaining 98% (95% CI 97.6%-98.4%) specificity regardless of the combinations used. When AU/mL concentrations of IgG antibodies from the MSD assay were compared against the corresponding IgG signals acquired from the single target commercial assays, the following correlations were observed: Abbott (vs MSD N, R2 = 0.73), Siemens (vs MSD RBD, R2 = 0.92), and EUROIMMUN (vs MSD S, R2 = 0.82). MSD assay offers an accurate and a comprehensive assessment of SARS-CoV-2 antibodies with higher sensitivity and equivalent specificity compared to the commercial IgG serology assays.