Fig. 7.

Closed Env conformation limits recognition of the V3 loop by tier 2 neutralizing, vaccine-induced antibodies. a CH505 TF gp120 and SOSIP trimer V3 amino acid sequence alignment. Amino acids idenitical to CH505 gp120 are shown as dots. b Surface plasmon resonance sensograms of antibody binding to serial dilutions of CH505 TF gp120, unstabilized SOSIP trimer that transitions to the open conformation, and SOSIP trimer stabilized in the closed conformation. Each row shows binding by an individual antibody. Each column shows binding to the specified version of HIV-1 Env. c Apparent equilibrium dissociation constants (K_D) for each antibody binding to the different forms of recombinant Env shown in b. Antibodies with binding magnitudes too weak to measure a K_D are listed as no binding. d, e Induction of trimer opening by soluble CD4 augments antibody binding to unstabilized trimers but not conformationally fixed, stabilized trimers. Surface plasmon resonance binding of rhesus monoclonal antibodies DH727.2, DH753, and DH796.1 to CH505 TF Env in the absence (open bar) or presence (filled bar) of soluble CD4. Antibody binding to d unstabilized CH505 TF trimer and e stabilized CH505 TF trimer is shown. The stabilized Env trimer (DS.SOSIP) contains the 201C-433C disulfide bond that prevents CD4 triggering. Symbols indicate independent measurements, and the bars represent the mean of the duplicate independent experiments. Source data are provided as a Source Data file