FIG. 3.

Fusion of TE and 633 with liposomes prepared from N18 or BHK cell lipids. Lipids were extracted from N18 (A) and BHK (B) cells and used to prepare liposomes. Pyrene-labeled TE or 633 viruses were mixed with liposomes at 37°C. At 0 s, the buffer pH was adjusted to 5.0 or maintained at 7.4, after which the change in pyrene excimer fluorescence intensity at 480 nm, due to dilution of the pyrene-labeled viral lipids into the liposome membrane, was monitored continuously.