Fig. 3.

Effect of cholesterol removal from cells on NDV infectivity. (a) NDV at 5 mois was allowed to bind to MβCD-treated and -untreated cells for 1 h at 4 °C, and was then transferred to 37 °C. At 24 h post-infection, viral infectivity was analyzed by a FACS-based immunoassay, probing with anti-F and anti-HN primary antibodies (see Materials and methods). The negative control corresponds to cells in the absence of virus with or without MβCD. (b) Effect of cholesterol depletion on the course of NDV entry. Monolayers of ELL-0 cells were infected with a 10^− 4 dilution of the recombinant rNDV-F3aa-mRFP NDV, meaning a moi of 1. At different times post-infection, 10 mM of MβCD and lovastatin were added for 1 h at 37 °C. After 24 h at 37 °C, infectivity was quantified as the number of red fluorescent cells out of the total number of cells in a fluorescent microscopy assay, and is referred to control untreated cells. Preincubation data refer to cells incubated with 10 mM of MβCD for 1 h at 37 °C before virus infection. Data are means ± SD of three independent experiments.