FIG 2.

Specificity and kinetics of the humoral immune response to ZIKV. (A and B) ZIKV-challenged nonhuman primate (NHP) IgG recognition of ZIKV particles harvested early (48 h) or late (144 h) postinfection of HEK293T cells (A) and ZIKV proteins (envelope [E], nonstructural protein 1 [NS1], and premembrane protein [pM]) (B) from five Asian (AS) and six African (AFR) lineages (Table 1). ZIKV-specific antibody responses are denoted by scatter plots with center horizontal lines representing the mean binding of serum antibodies from NHPs challenged with either an AFR (n = 3) (circles) or AS (n = 3) (squares) lineage ZIKV at 0 to 2 days postinfection (dpi) (open symbols) and 21 to 28 dpi (filled symbols). Error bars indicate SEM. Statistically significant differences between mean antibody binding of all ZIKV-challenged NHPs to ZIKV antigens at 0 to 2 dpi and 21 to 28 dpi were calculated using a one-tailed Student's t test (*, P < 7.5e−5; ns, not significant), while no significant differences were observed between mean antibody binding of ZIKV-AS- and ZIKV-AFR-challenged groups to AS and AFR ZIKV antigens at 21 to 28 dpi (two-tailed Student's t test). (C) IgM and IgG binding profiles to ZIKV particles (harvest at 144 h) and ZIKV E protein are compared to viral load (Zika Open-Research Portal [https://zika.labkey.com]) from preinfection (day 0) to 28 dpi for ZIKV-challenged NHPs (n = 9). Second-order (IgM), third-order (IgG), and fourth-order (viral load) polynomial curves were fitted to the data, with fitted lines and shading under the curve consistent with data point colors.