Ultrasensitive high-resolution profiling of early seroconversion in patients with COVID-19

Norman, Maia; Gilboa, Tal; Ogata, Alana F.; Maley, Adam M.; Cohen, Limor; Busch, Evan L.; Lazarovits, Roey; Mao, Chih-Ping; Cai, Yongfei; Zhang, Jun; Feldman, Jared E.; Hauser, Blake M.; Caradonna, Timothy M.; Chen, Bing; Schmidt, Aaron G.; Alter, Galit; Charles, Richelle C.; Ryan, Edward T.; Walt, David R.

Sensitive assays are essential for the accurate identification of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we report a multiplexed assay for the fluorescence-based detection of seroconversion in infected individuals from less than 1 µl of blood, and as early as the day of the first positive nucleic acid test after symptom onset. The assay uses dye-encoded antigen-coated beads to quantify the levels of immunoglobulin G (IgG), IgM and IgA antibodies against four SARS-CoV-2 antigens. A logistic regression model trained using samples collected during the pandemic and samples collected from healthy individuals and patients with respiratory infections before the first outbreak of coronavirus disease 2019 (COVID-19) was 99% accurate in the detection of seroconversion in a blinded validation cohort of samples collected before the pandemic and from patients with COVID-19 five or more days after a positive nasopharyngeal test by PCR with reverse transcription. The high-throughput serological profiling of patients with COVID-19 allows for the interrogation of interactions between antibody isotypes and viral proteins, and should help us to understand the heterogeneity of clinical presentations.