FIG. 7.

Results of luciferase assay to determine fusion ability of SIV TM mutants. COS-1 cells were transfected with pSREB (control), pSRSEB (wild type), and pTM185EB to pTM189EB as described in the legend to Fig. 3 except that at 48 h posttransfection, the COS-1 cells were mixed with JC53-BL target cells. After overnight incubation, cells were lysed and measured for luciferase activity. The fusion efficiencies from the luciferase assay and the lipid dye transfer assay were compared for SIV wild-type Env (WT) and TM truncation mutants.