TABLE 1.
HIV-1 coreceptor activities and fusion-enhancing activities of WT and mutant US28
| US28 expression vector | HIV-1 core- ceptor activity (no. of syncytia)a | Effect on VSV-G fusion (no. of syncytia)b | Fusion enhancement (fold) |
|---|---|---|---|
| None (Rc/CMV) | 2 ± 0.8 | 564 ± 147 | 1 |
| WT US28 | 643 ± 176 | 1,033 ± 127 | 1.8 |
| MYC-tagged US28 (NT insertion) | 163 ± 102 | 1,533 ± 125 | 2.7 |
| Mutant US28 | |||
| Δ2-22 (NT deletion) | 1.3 ± 0.5 | 1,313 ± 123 | 2.3 |
| Δ317 (CT deletion) | 713 ± 75 | 1,850 ± 234 | 3.3 |
| K158V K159V (ECL2) | 770 ± 64 | 653 ± 148 | 1.2 |
| K257V (ECL3) | 115 ± 26 | 1,243 ± 95 | 2.2 |
| E266V R267V (ECL3) | 1 ± 0.8 | 1,569 ± 81 | 2.8 |
a
US28 mutants were expressed in HeLa P4 cells (CD4+ LTRlacZ) and cocultured with HeLa-Env/ADA cells. The numbers of blue-stained foci per well (six-well trays; means and standard deviations for triplicate wells) after staining with X-Gal are shown.
b
US28 mutants and VSV-G were coexpressed in HeLa-Tat cells and cocultured with U87MG-CD4-LTRlacZ cells. The numbers of blue-stained foci per well (six-well trays; means and standard deviations) after staining with X-Gal are shown. No fusion was detected if VSV-G was omitted.