BG505 Env PV mutants used to map serum neutralization targets.

(A) Env PVs containing mutations that affect four major nAb targets on the BG505 Env were used (HXB2 numbering): V1 residues 133/136, a glycan hole located near positions 241 and 289, the C3/465 glycan hole cluster, and a region proximal to N611 near the trimer base. The substitutions that shift or add a glycan motif in BG505 Env generally result in a reduction in neutralization sensitivity; removal of the N355 (T357A), N398, and N611 glycan motifs from the BG505 Env generally results in an increase in neutralization sensitivity. (B) Amino acid residues at positions 131–137 in V1 of the BG505 WT and the 133aN and 133aN + 136aA mutants shows the shift of a glycan and elongation of the V1 loop. (C) Amino acid residues 355–358 in C3 for BG505 WT and the TI357KT mutant show a glycan shift and sequence changes. Glycan motifs are highlighted in gray, with bolded text, and mutations or insertions are indicated in red.

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