Figure 2.

Correlation of anti-S1 OD ratio with anti-spike IgG titer and neutralizing activity (ppNT₅₀ and PRNT₅₀) in sera from 50 patients. A, Correlation of OD ratio values against S1 antigen with the antibody titers against spike antigen and the neutralizing titers against the pseudotyped lentivirus (ppNT₅₀) or MERS-CoV (PRNT₅₀) were assessed (left panels). Nonlinear regression curves (exponential growth) and goodness of curve fit (r² value) are presented. B, Kinetic changes of anti-S IgG titers and neutralizing activity (ppNT₅₀ and PRNT₅₀) in sera samples are presented in clinical severity groups (GI ~ GIII). Box and whiskers (min to max) plots including median (black line) and mean (+) values of each plot are presented at the indicated time points (G-I: n = 11, G-II: n = 23, and G-III: n = 16). Abbreviations: IgG, immunoglobulin G; MERS-CoV, Middle East respiratory syndrome coronavirus; OD, optical density.