Fig. 6: Structural analysis of the B41 Env SOSIP trimer–FD22 Fab complex. | Cell Discovery

Fig. 6: Structural analysis of the B41 Env SOSIP trimer–FD22 Fab complex.

From: A potent and broad CD4 binding site neutralizing antibody with strong ADCC activity from a Chinese HIV-1 elite neutralizer

Fig. 6

a Superimposition of CD4bs antibodies on gp120. Structural alignment of six CD4 binding site (CD4bs) antibodies in complex with gp120: VRC01 (PDB ID: 8VGW), CH235.12 (PDB ID: 8VH2), 1-18 (PDB ID: 6UDJ), 3BNC117 (PDB ID: 5V8M), and N6 (PDB ID: 5TE6). b Close-up of the interactions of CDRH3 with gp120. Detailed view of the interaction between FD22 CDRH3 and gp120, highlighting residues involved in hydrogen bonding. c Electrostatic surface potential of gp120. Surface electrostatic potential mapping of gp120, corresponding to the region shown in (a). d Neutralization activity of FD22 variants against pseudotyped viruses across different clades. Variants exhibiting reduced neutralization potency are color-coded based on the magnitude of change: red indicates >10-fold increase in IC50, while yellow represents a 5–10-fold increase. e Neutralization sensitivity of the resistant autologous virus SGA14 and its mutants to FD22. The resistant autologous virus SGA14, derived from P27, was engineered by substituting the V2 Loop, Loop D, CD4 BLP, and V5 Loop of HXBc2 Env into SGA14. Sequence variations in the P27 autologous virus relative to the HXBc2 reference are highlighted in red, with reverse mutations indicated in bold and underlined. IC50 values are represented using a color code: red (<0.1 μg/mL), orange (0.1–1 μg/mL), and yellow (>1 μg/mL). VRC01 was included as a control for comparative analysis. f Detailed view of FD22 Fab interactions with gp120 Loop D. Predicted interactions between FD22 Fab and the Loop D region of gp120, highlighting residues involved in hydrogen bonding. AlphaFold3 parameters: ModelSeeds = 1692646031, ranking score = 0.63. Additional details are provided in Supplementary Table S4. g Detailed view of FD22 Fab interactions with the CD4 BLP. Predicted structural interactions between FD22 Fab and the CD4 BLP of gp120, with residues forming hydrogen bonds highlighted. AlphaFold3 parameters: ModelSeeds = 1692646031, ranking score = 0.63. Additional details are provided in Supplementary Table S4. h Local superimposition of the predicted FD22 Fab-HXBc2 SOSIP and FD22 Fab-SGA14 SOSIP complexes. Structural alignment of the predicted FD22 Fab in complex with HXBc2 SOSIP and SGA14 SOSIP, showing residues involved in hydrogen bonding.

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