A multiplex antigen microarray for simultaneous IgG and IgM detection against SARS‐CoV‐2 reveals higher seroprevalence than reported

Abstract

The surge of SARS‐CoV‐2 has challenged health systems worldwide and efficient tests to detect viral particles, as well as antibodies generated against them, are needed. Specificity, sensitivity, promptness or scalability are the main parameters to estimate the final performance, but rarely all of them match in a single test. We have developed SCOVAM, a protein microarray with several viral antigens (spike, nucleocapsid, main protease Nsp5) as capturing probes in a fluorescence immunoassay for COVID‐19 serological testing. SCOVAM depicts IgG and IgM antibody responses against each of these proteins of 22 individuals in a single microscope slide. It detects specific IgM (0.094 μg ml‐1) and IgG (~0.017 μg ml‐1) and is scalable and cost‐effective. We validated SCOVAM by comparing with a widely used chemiluminescent commercial serological test (n = 742). SCOVAM showed twice the sensitivity and allowed following seroconversion in a single assay. By analysing the prevalence 4 months later in a subset of 76 positive sera, we still detected 93.42% of positives, almost doubling the detection of the commercial assay. The higher sensitivity of SCOVAM is especially relevant to screen sera for convalescent plasma‐based treatments, high‐throughput antibody response monitoring after vaccination or evaluation of vaccine efficiency. ; This work has been funded by INTA's internal budget and the Spanish Ministry of Science and Innovation grant nos. RTI2018‐094368‐B‐I00, and MDM‐2017‐0737 (Excelencia 'María de Maeztu' to Centro de Astrobiología). The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. DRG is funded by the 'Programa de Atracción de Talento' of local Government of Madrid. Centro Superior de Investigaciones Cientificas: project number 202020E079. ; Peer reviewed