FIG 3.

Schematic of the wt and modified forms of the gp120 V1/V2 and V3 loops. The sequences of wt and modified V3 (A) and V1/V2 (B) loops are shown with disulfide bonds depicted as black lines. Amino acid numbering corresponds to BaL gp120. Landmark cysteine residues are numbered for convenience. wt sequences are shown in black, and altered sequences are shown in gray. (A) V3 loop mutants, including (i) the wt V3 loop, (ii) V3 base (gp120 with a partially truncated V3 loop), and (iii) ΔV3 (gp120 with a truncated V3 loop). (B) V1/V2 loop mutants, including (i) wt V1/V2 loops, (ii) ΔV1 (gp120 with a truncated V1 loop), (iii) ΔV2 (gp120 with a truncated V2 loop), (iv) ΔV1V2 (gp120 with truncated V1/V2 loops), and (v) ΔH1 (gp120 with truncated V1/V2 loops and stem).