Dimeric IgA is a specific biomarker of recent SARS-CoV-2 infection.

Abstract

Current tests for SARS-CoV-2 antibodies (IgG, IgM, IgA) cannot differentiate recent and past infections. We describe a point of care, lateral flow assay for SARS-CoV-2 dIgA based on the highly selective binding of dIgA to a chimeric form of secretory component (CSC), that distinguishes dIgA from monomeric IgA. Detection of specific dIgA uses a complex of biotinylated SARS-CoV-2 receptor binding domain and streptavidin-colloidal gold. SARS-CoV-2-specific dIgA was measured both in 112 cross-sectional samples and a longitudinal panel of 362 plasma samples from 45 patients with PCR-confirmed SARS-CoV-2 infection, and 193 discrete pre-COVID-19 or PCR-negative patient samples. The assay demonstrated 100% sensitivity from 11 days post-symptom onset, and a specificity of 98.2%. With an estimated half-life of 6.3 days, dIgA provides a unique biomarker for the detection of recent SARS-CoV-2 infections with potential to enhance diagnosis and management of COVID-19 at point-of-care.

• Authors: Heidi E Drummer, Huy Van, Ethan Klock, Shuning Zheng, Zihui Wei, Irene Boo, Rob J Center, Fan Li, Purnima Bhat, Rosemary Ffrench, Jillian Sy Lau, James McMahon, Oliver Laeyendecker, Reinaldo E Fernandez, Yukari C Manabe, Sabra L Klein, Thomas C Quinn, David A Anderson
• Journal: medRxiv : the preprint server for health sciences (medRxiv) (Jul 01 2021) United States
• PMID: 34230936 (Publication Type: Preprint)