FIG 6.

Use of alternative coreceptors by SIVmac239, iMac239, and iMac239-ΔD385. (A) Fusion activity of the indicated Envs on rhesus coreceptors in the presence (left) or absence (right) of rhesus CD4 was assessed in a cell-cell fusion assay. In each panel, luciferase activity was normalized to values for rhesus CCR5. Background fusion levels were subtracted prior to normalization. Data shown are the means from three experiments plus SEM. (B) Replication of SIVmac239, iMac239, and iMac239-ΔD385 viruses in CD4⁺ CCR5⁻ CEMx174 (left) and HUT-78 (right) cells. RT activity in culture supernatants was measured at the indicated time points. Results from a representative experiment are shown.