The effect of oligomerization on Env antigenicity. The sensorgrams show the binding (RU) of the listed IgGs to the BG505 SOSIP.664 trimer, gp120-gp41ECTO protomer (gp140), and monomeric gp120 over time (s) on the x axis. Association was followed for 5 min and dissociation for 10 min. The Env proteins were captured on the chip by amine-coupled D7324 antibody. For each Ab tested similar levels of Env were captured: R
values were ~ 500 RU for trimers and protomers for all Abs except for the V3-specific ones, where R
was ~200 RU for trimer and protomer, and in all cases ~15% lower for gp120 to yield approximately equal numbers of gp120 subunits for all three forms of Env. The antibodies tested as analytes bind to different clusters of epitopes: b12, b6, and VRC01 to the CD4bs; F240 to cluster I in gp41; PG9, PG16, and PGT145 to V1V2-glycan epitopes at the apex of the trimer; PGT151 to a newly discovered epitope that spans the interface between gp120 and gp41ECTO in one protomer and also makes contact with a second gp41ECTO subunit; 2G12 to a mannose-glycan-dependent epitope; PGT123 and PGT128 to composite V3-base and glycan epitopes; and 14e and 19b to V3 epitopes. MAbs b12, b6, F240, 14e, and 19b do not neutralize the corresponding BG505.T332N virus, whereas VRC01, 2G12, PGT123, PGT128, PG9, PG16, PGT145, and PGT151 do. All MAbs were injected at 1 μM. The sensorgrams show one of two replicates.