Table 1.

HIV-1 coreceptor activities and fusion-enhancing activities of WT and mutant US28

US28 expression vectorHIV-1 core- ceptor activity (no. of syncytia)aEffect on VSV-G fusion (no. of syncytia)bFusion enhancement (fold)
None (Rc/CMV)2 ± 0.8564 ± 1471
WT US28643 ± 1761,033 ± 1271.8
MYC-tagged US28 (NT insertion)163 ± 1021,533 ± 1252.7
Mutant US28
 Δ2-22 (NT deletion)1.3 ± 0.51,313 ± 1232.3
 Δ317 (CT deletion)713 ± 751,850 ± 2343.3
 K158V K159V (ECL2)770 ± 64653 ± 1481.2
 K257V (ECL3)115 ± 261,243 ± 952.2
 E266V R267V (ECL3)1 ± 0.81,569 ± 812.8
  • 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.