A flow cytometry‐based assay to measure neutralizing antibodies against SARS‐CoV‐2 virus

• Published in: Cytometry. Part A Vol. 105; no. 6; pp. 446 - 457
• Main Authors: Pscheidt, Veridiane M., Souza, Priscila Oliveira, Fazolo, Tiago, Modena, José Luiz Proença, Simeoni, Camila, Teixeira, Daniel, Silva, Natália Brunetti, Santos, Karina Bispo, Júnior, Luiz Rodrigues, Bonorino, Cristina
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-06-2024; Wiley Subscription Services, Inc
• Subjects: Antibodies; Antibodies, Neutralizing - blood; Antibodies, Neutralizing - immunology; Antibodies, Viral - blood; Antibodies, Viral - immunology; Assaying; Biosafety; COVID-19; COVID-19 - diagnosis; COVID-19 - immunology; COVID-19 - virology; COVID-19 Serological Testing - methods; Dilution; Female; Flow cytometry; Flow Cytometry - methods; Humans; Male; Neutralization Tests - methods; Neutralizing; Pandemics; PRNT; S protein; SARS-CoV-2 - immunology; Sensitivity and Specificity; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; Spike Glycoprotein, Coronavirus - immunology; Viral diseases; Viruses; flow cytometry; COVID‐19; S protein; PRNT
• ISSN: 1552-4922; 1552-4930
• DOI: 10.1002/cyto.a.24838

The COVID‐19 pandemic caused by the SARS‐CoV‐2 virus has highlighted the need for serological assays that can accurately evaluate the neutralizing efficiency of antibodies produced during infection or induced by vaccines. However, conventional assays often require the manipulation of live viruses on a level‐three biosafety (BSL3) facility, which presents practical and safety challenges. Here, we present a novel, alternative assay that measures neutralizing antibodies (NAbs) against SARS‐CoV‐2 in plasma using flow cytometry. This assay is based on antibody binding to the S protein and has demonstrated precision in both intra‐ and inter‐assay measurements at a dilution of 1:50. The cut‐off was determined using Receiver Operating Characteristic (ROC) analysis and the value of 36.01% has shown high sensitivity and specificity in distinguishing between pre‐pandemic sera, COVID‐19 patients, and vaccinated individuals. The efficiency significantly correlates with the gold standard test, PRNT. Our new assay offers a safe and efficient alternative to conventional assays for evaluating NAbs against SARS‐CoV‐2.