TABLE 1.
Characterization of HIV-1YU2 gp120 W69 variantsg
| Env | Association indexa | Processing indexb | Infectivityc | IC50 (μg/ml) of CD4bs ligandd |
Cell-cell fusione | Immunoprecipitation resultf (gp120 monomer) |
|||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| sCD4 | VRC01 | VRC13 | VRC16 | CoRBS antibody |
Anti-cluster A antibody |
CD4bs antibody |
|||||||||||||
| 17b | 48d | A32 | N5-i5 | N60-i3 | CD4-Ig | VRC01 | VRC03 | VRC13 | VRC16 | b12 | |||||||||
| WT | 1.00 | 1.00 | 1.00 | 2.25 | 0.59 | 2.90 | 0.56 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| W69G | 0.58 | 0.20 | 0.01 | NA | NA | NA | NA | 0.10 | 0.47 | 0.18 | 0.09 | 0.05 | 0.03 | 0.73 | 1.12 | 1.67 | 1.72 | 4.57 | 1.56 |
| W69A | 0.57 | 0.27 | 0.05 | 2.77 | 0.23 | 1.07 | 0.13 | 0.54 | 0.38 | 0.18 | 0.08 | 0.15 | 0.01 | 0.69 | 1.05 | 1.50 | 1.41 | 3.94 | 1.72 |
| W69I | 0.81 | 0.51 | 0.19 | 5.43 | 0.24 | 2.07 | 0.24 | 0.51 | 0.34 | 0.12 | 0.07 | 0.10 | 0.01 | 0.57 | 0.95 | 1.60 | 1.24 | 2.33 | 1.81 |
| W69L | 1.40 | 0.55 | 0.51 | >10 | 0.21 | 1.65 | 0.18 | 0.75 | 0.36 | 0.14 | 0.15 | 0.10 | 0.05 | 0.52 | 1.02 | 1.25 | 1.29 | 2.87 | 1.98 |
| W69F | 1.31 | 0.91 | 1.16 | 2.51 | 0.66 | 3.30 | 0.66 | 0.88 | 0.90 | 0.83 | 1.09 | 1.17 | 0.94 | 0.69 | 0.93 | 0.59 | 0.89 | 0.66 | 0.92 |
| W69A/S115W | 0.44 | 0.28 | 0.01 | NA | NA | NA | NA | 0.03 | 0.51 | 0.21 | 0.15 | 0.10 | 0.00 | 1.03 | 1.16 | 1.65 | 1.63 | 3.39 | 1.38 |
The association index is a measure of the ability of the mutant gp120 molecule to remain associated with the envelope glycoprotein complex on the expressing cell relative to that of the wild-type envelope glycoproteins. The calculation method is described in Materials and Methods.
The processing index is a measure of the conversion of the mutant gp160 envelope glycoprotein precursor to mature gp120 relative to that of the wild-type envelope glycoproteins. The calculation method is described in Materials and Methods.
The infectivity was assessed on Cf2Th-CD4/CCR5 cells using RT-normalized amounts of pseudoviruses of the WT and W69 variants. Data shown here are the ratios of mutant to wild-type virus infectivity.
The ligand (sCD4, VRC01, VRC13, and VRC16) concentrations that inhibited the infection of pseudoviruses of the WT and W69 variants by 50% (IC50) are reported. NA, not applicable, since infectivity was too low to perform the neutralization experiment.
Cell-cell fusion activity was assessed by coincubation between 293T cells expressing Env variants and TZM-bl cells for 6 h at 37°C. Luciferase activity in the mixture of cell lysate was measured to determine the cell-to-cell fusion efficiency.
Comparable amounts of radiolabeled monomeric gp120 from the WT and W69 variants were incubated with 5 μg/ml of coreceptor binding antibodies (17b and 48d), anti-cluster A antibodies (A32, N5-i5, and N60-i3), CD4-Ig, and CD4-binding site antibodies (VRC01, VRC03, VRC13, VRC16, and b12) for 1 h at 37°C. The precipitates were washed, run on SDS-polyacrylamide gels, and analyzed by densitometry.
Values presented in this table represent the means of data from at least three independent experiments, with experimental variation typically not more than 20% of the value reported. When WT values were normalized to 1, signals of ≤0.5 are in boldface, and values of ≥1.5 are in italics.