Fig. 1.

Effect of cellular cholesterol removal on NDV fusion. (a) Uninfected avian ELL-0 cell monolayers were incubated in the presence of increasing concentrations of MβCD for 1 h at 37 °C. Cholesterol was extracted and quantified as described in Materials and methods. Data are means ± standard deviations of three independent experiments. (b) R18-labeled NDV was bound to MβCD-treated cells and untreated cells (control) for 1 h at 4 °C, after which they were allowed to fuse for 1 h at 37 °C. Fusion was assessed by transfer of the R18 red dye to the cell membrane. As a control of non-specific dye transfer, NDV was inactivated by incubation at 100 °C for 2 min (NDV-R18 inact). In these samples, non-significant dye transfer was observed in both untreated and MβCD-treated cells.