Fig 3.

(A) Amino acid alignment of envelope regions of S208 variants. The sequence for S208 M^sens1 is shown. Symbols: dashes, amino acids similar to those in S208 M^sens1; dots, deletions; x, loss of PNGS in B^res; +, gain of PNGS in B^res. Modifications in PNGS highlighted are relative to one or both of the sensitive maternal variants. Constant (C1 to C5) and variable (V1 to V5) regions of the surface gp120 subunit of the envelope are indicated. For gp41, abbreviations are as follows: FP, fusion peptide; HR1, heptad region 1; HR2, heptad region 2; MPER, membrane-proximal external region; MSD, membrane-spanning domain; CT, cytoplasmic tail. Neutralization profiles of S208 pseudoviruses bearing chimeric envelopes from B^res and M^sens1 (B) or B^res and M^sens2 (D) against maternal plasma are shown. Average IC₅₀s from at least 2 independent experiments are shown next to bars representing chimeric envelopes. Gray bars represent envelope sequence of M^sens1 or M^sens2. White bars represent envelope sequence of B^res. Asterisks denote regions in B^res with amino acid differences relative to the maternal envelope. The right-side-up triangle represents deletion in B^res. The inverted triangle represents insertion in B^res. Neutralization curves of chimeric viruses bearing regions found to confer resistance to maternal plasma (V4 in panel C and HR2 in panel E) are shown relative to native maternal and infant viruses. Percent neutralization versus plasma dilution is shown.