Cross-competition ELISA.

<p>Titration series of sera from two weeks after the third protein boost were competed with biotinylated mAbs or biotinylated soluble domains 1–4 monomeric CD4 using UG37 gp140 as the antigen and 50% inhibition titers (IT50) were calculated as the serum dilution at which binding of the biotinylated probes was reduced by 50% compared to control well without serum. Epitopes targeted by the mAbs are specified in parentheses. CD4bs: CD4 binding site; CD4i: CD4 inducible epitope. A one-way ANOVA was performed for each competing protein/antibody with Dunnett’s post-hoc tests to compare Group 1 and Group 3 with the control Group 2. Significance is illustrated by **p<0.001.