Fig. 5: Neutralizing titers for SARS-CoV-2 and SARS-CoV in COVID-19 subject plasma.

a Neutralization assay with S-RBD-specific NAb, healthy control plasma, and a COVID-19 patient plasma. Threefold serial dilutions of NAb from 10 μg/ml to 1 ng/ml or the plasma from 1:10 to 1:10,000 were pre-incubated with spike protein pseudovirus and added to 293-ACE2 cells. GFP expression was analyzed by flow cytometry 3 days post infection. b SARS-CoV-2 neutralization titers (NT50) of COVID-19 plasma grouped as an outpatient, hospitalized, ICU or deceased and convalescent plasma donor groups (n = 113). c NT50 of COVID-19 patient and plasma donor groups subdivided into males and females (n = 113). d Comparison of NT50 of COVID-19 plasma for SARS-CoV-2 and SARS-CoV neutralization. SARS-CoV-2 or SARS-CoV pseudoviruses were pre-incubated with COVID-19 plasma from all severity groups (n = 104), 293-ACE2 cells were infected and RFP expression was determined at day 3 using flow cytometry. e Graph of SARS-CoV-2 NT50 values from hospitalized subjects plotted against SARS-CoV (n = 46). Two-tailed Mann–Whitney U test was used to determine the statistical significances in figures (b), (c) and (d) and two-tailed Spearman’s was used for figure (e). Horizontal bars in (b), (c) and (d) indicate mean values.