Figure 4.

Cell–cell fusion assay using parental PM1 cells (PM1-P) and clones derived from the control transduced PM1 cells (PM1-RAI3–5) and from PM1 cells transduced with ST6-encoding retrovirus (PM1–6-G). PM1 cells were infected with a vaccinia recombinant encoding T7 RNA polymerase. To assess background luciferase activity, parental PM1 cells were infected with vaccinia virus encoding β-galactosidase instead (PM1-P-lacZ). Reporter gene activity upon coculturing of PM1 cells with 293T cells expressing HIV-1 env and transfected with reporter plasmid is shown as relative light units (RLU) on the y-axis. Pairs of individual experiments are shown.