Sensitive detection of total anti-Spike antibodies and isotype switching in asymptomatic and symptomatic individuals with COVID-19
Yun Shan Goh, Jean‐Marc Chavatte, Alicia Lim Jieling, Bernett Lee, Pei Xiang Hor, Siti Naqiah Amrun, Cheryl Yi‐Pin Lee, Rhonda Sin‐Ling Chee, Bei Wang, Chia Yin Lee, Eve Zhi Xian Ngoh, Cheng‐I Wang, Barnaby Edward Young, Paul Anantharajah Tambyah, Shirin Kalimuddin, Surinder Pada, Seow Yen Tan, Louisa Sun, Mark Chen, Yee‐Sin Leo, David Chien Lye, Lisa F. P. Ng, Raymond Tzer Pin Lin, Laurent Rénia
Abstract
Early detection of infection is crucial to limit the spread of coronavirus disease 2019 (COVID-19). Here we develop a flow cytometry-based assay to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein antibodies in individuals with COVID-19. The assay detects specific immunoglobulin M (IgM), IgA, and IgG in individuals with COVID-19 and also acquisition of all IgG subclasses, with IgG1 being the most dominant. The antibody response is significantly higher at a later stage of infection. Furthermore, asymptomatic individuals with COVID-19 also develop specific IgM, IgA, and IgG, with IgG1 being the most dominant subclass. Although the antibody levels are lower in asymptomatic infection, the assay is highly sensitive and detects 97% of asymptomatic infections. These findings demonstrate that the assay can be used for serological analysis of symptomatic and asymptomatic infections, which may otherwise remain undetected.