Cross-species antibody recognition of the HIV-1 V2 apex site of vulnerability and their induction by SHIV. (a) Summary of rhesus and human structural modes of HCDR3-dominated V2 apex recognition. Roman numerals denote the neutralization mapping group (groups I–V) for each lineage as detailed in extended data Fig. 2 D; infecting SHIV strain and antibody class are also delineated as detailed in extended data Table S2 and extended data Fig. 6, respectively. (b–d) The 5-Å Env footprints of the most broadly neutralizing rhesus (top) and human (bottom) lineages with needle-like (b), axe-like (c), and combined (d) modes of recognition are mapped in red onto each respective trimer complex. The remaining gp120 surface is shown in gray, and all other components of the structure are omitted for clarity. Top view of trimer. (e) Epitope and paratope characteristics of V2 apex lineages compared across species and extended class. Each plot is a different structural feature that groups lineages by host species on the left and HCDR3 topology on the right. P values are only listed for statistically significant differences (*, P < 0.05; ***, P < 0.0005; unpaired t test) between two groups on the same side of the plot.