Fig. 4.

SPR and B-cell activation analysis of BG505 and ConM SOSIP-I53-50NP. a Each pair of sensorgrams shows the binding of SOSIP trimer (left) and SOSIP-I53-50NPs (right) to immobilized IgG of the bNAbs indicated above the sensorgrams. Trimers and NPs were titrated at a constant ratio of concentrations corresponding to equal amounts of SOSIP per volume as indicated in the color code to the right. Langmuir model fits in black are overlaid on the colored binding curves for each concentration. Please note that although Langmuir curves were fitted, no kinetic modeling was performed due to severe mass-transport limitations (for further explanation, see SOSIP trimer and SOSIP-I53-50NP binding to immobilized mAbs by SPR in Supplementary Methods). b The difference in macromolecules of SOSIP trimer or SOSIP-I53-50NP bound to several immobilized bNAbs plotted as a ratio (left) and a model of SOSIP (gray) presented on the I53-50NP (I53-50A in beige, I53-50B.4PT1 in light blue) with the corresponding bNAb footprints shown. c Activation of PGT145, VRC01, and PGT121-expressing B cells, measured by Ca²⁺ flux over 210 seconds for BG505 and ConM SOSIP-I53-50NPs (purple), ConM SOSIP-ferritin (orange), and the corresponding trimer (green). Unmodified I53-50NPs (red) were included to determine nonspecific activation by the I53-50NP core. Blanc, for which PBS was used, functioned as an additional negative control (blue). Source data are provided as a Source Data file