FIG 1.
HIV-1AD8 Env modification guided by natural polymorphisms. (A) Natural polymorphisms in HIV-1 Env were used to suggest amino acid residues that might tolerate replacement with a lysine residue or with acidic amino acid residues. The lysine substitutions are grouped according to the Env region in which the residues are located. Compared with sets 1 to 3, sets 4 to 7 contain an increased number of substitutions. (B) A schematic representation of the HIV-1AD8 Env glycoprotein is shown, with the gp120-gp41 cleavage site depicted as a black triangle. S, signal peptide; V1 to V5, gp120 major hypervariable regions; FP, fusion peptide; HR, heptad repeat region; TM, transmembrane region; CT, cytoplasmic tail. The amino acid changes associated with some of the key Env variants studied here are shown. Red vertical tick marks indicate changes in addition to those found in the 2–4 R Env.