Fig. 6: AMP-CpG immunization stimulates rapid and potent humoral responses to multiple variants of SARS-CoV-2 in NHPs.

Rhesus macaques (n = 2/3) were immunized as shown in Fig. 5a and humoral responses to SARS-CoV-2 were assessed in lymph node FNA and serum at various timepoints. a, b Shown are frequencies of Tetramer⁺ RBD-specific GC B cells (CD20⁺ BcL6⁺ Ki-67⁺) in lymph node FNAs at baseline and week 6 with corresponding representative flow cytometry dot plots of RBD-specific B cells. RBD-specific serum IgG binding unit concentrations were assessed for WH-01 (c) and VOC (d) RBD-binding activity, either longitudinally or at baseline and week 6. e, g Neutralizing antibody responses were determined through pseudovirus inhibitory activity. Shown are ID₅₀ values for WA1 (e), Delta (f), and Omicron (g) in comparison to convalescent human plasma (CHP). Values depicted are means±standard deviation. The dotted lines represent the lower limit of detection discriminating between the samples positive or negative for seroconversion and the mean value observed for the human plasma comparators where appropriate. ^*p < 0.05; ^**p < 0.01 by two-sided Mann-Whitney test (a, e–g), or paired one-way ANOVA followed by Dunnett’s post-hoc analysis (c, d).