Table 2. Characterization of ligand binding to selected HIV-1BG505 variants by cell-based ELISA. a .
| HIV-1BG505 Env variant | |||||||
|---|---|---|---|---|---|---|---|
| Env subunit | Epitope | Ligand | wt | S375W | I559P | SOS | SOSIP |
| gp120 | CD4-BS | VRC01 | 1.00 | 0.79 | 0.51 | 0.82 | 0.52 |
| CD4-BS | b12 | 1.00 | 1.72 | 0.19 | 1.09 | 0.73 | |
| CD4-BS | CD4-Ig | 1.00 | 1.42 | 0.31 | 1.35 | 0.74 | |
| V3 | 19b | 1.00 | 1.26 | 0.30 | 1.87 | 0.66 | |
| V3 | GE2 JG8 | 1.00 | 1.54 | 0.38 | 2.57 | 0.96 | |
| V3 glycans | PGT121 | 1.00 | 1.29 | 1.73 | 1.04 | 1.59 | |
| V2 glycans | PG9 -sCD4 | 1.00 | 0.84 | 0.71 | 1.01 | 0.66 | |
| V2 glycans | PG9 +sCD4 | 0.68 | 0.48 | 0.61 | 0.65 | 0.57 | |
| CD4i | 17b -sCD4 | 1.00 | 3.56 | <0.01 | 2.68 | 1.13 | |
| CD4i | 17b +sCD4 | 21.80 | 61.87 | 12.66 | 35.86 | 20.45 | |
| CD4i | A32 -sCD4 | 1.00 | 2.54 | 0.03 | 1.47 | 0.08 | |
| CD4i | A32 +sCD4 | 2.59 | 9.81 | 0.19 | 5.70 | 0.62 | |
| gp120-gp41 | gp120-gp41 interface | PGT151 - sCD4 | 1.00 | 0.45 | 0.34 | 0.98 | 0.33 |
| gp120-gp41 interface | PGT151 + sCD4 | 0.68 | 0.24 | 0.28 | 0.56 | 0.26 | |
| gp120-gp41 interface | 35O22 - sCD4 | 1.00 | 1.47 | 1.48 | 1.00 | 1.72 | |
| gp120-gp41 interface | 35O22 + sCD4 | 1.02 | 0.96 | 1.84 | 1.15 | 2.32 | |
| gp120-gp41 interface | ps b | 1.00 | 0.99 | 0.17 | 0.38 | 0.26 | |
| gp41 | MPER | 4e10 | 1.00 | 1.40 | 0.48 | 1.24 | 0.96 |
| Cluster I | 7b2 | 1.00 | 1.08 | 0.04 | 0.09 | 0.02 | |
| Cluster I | F240 | 1.00 | 1.22 | 0.03 | 0.25 | 0.07 | |
| Cluster II | 2.2b | 1.00 | 1.13 | <0.01 | 0.55 | 0.18 | |
a For the cell-based ELISA experiments, a stop codon was introduced in place of the codon for glycine 711 to truncate the cytoplasmic tail (ΔCT) and enhance cell-surface expression of the indicated HIV-1BG505 envelope glycoproteins. Ligand binding was measured by cell-based ELISA, as described in the Materials and Methods. Each signal was normalized for the relative level of Env expression by the binding of the 2G12 antibody. The cell-surface expression of the four Env mutants, as determined by 2G12 binding, was comparable and exhibited no greater than 20% variation from the level of the wt Env. The ligand-binding values relative to those associated with the wt Env in the absence of sCD4 are reported.
b The reported values for polyclonal serum (ps) from an HIV-1-infected individual represent the average obtained with serum from one HIV-1-infected individual; however, similar results were obtained with sera from more than six randomly selected HIV-1-infected individuals.
Values presented in this table represent the mean of at least four independent experiments done in quadruplicate, with experimental variation typically not more than 20% of the value reported. In bold are values that are statistically different (p≤0.05) from those of the wt Env, as measured by a paired t test.