Fig. 5.

IFN α treatment and IFITMs directly block viral fusion. a THP1 wild-type or overexpressing IFITM3-HA were treated for 24 h with 0 or 1000 U/mL IFNα for 24 h, and then infected with the indicated amount of HIV-1Δenv(VSV-G) packaging the Vpr-β-lactamase fusion protein for 3 h. Cells were then incubated with the fluorescent CCF2-AM substrate for 2 h, fixed, and acquired by flow cytometry immediately. Representative flow cytometry plots are shown. b Representative dose response experiment. Solid black line: wild-type THP1 cells, dashed black line: wild-type THP1 treated with IFNα, grey dashed line: THP1 cells overexpressing IFITM3. c Combined data from three independent experiments, using a viral dose within linear range. **p < 0.01 (paired t test). d THP1 cells wild-type (in black) or knockout for IFITM2/3 (in grey) were treated with IFNα (dashed lines) or untreated (solid lines) and infected with the indicated amount or HIV∆env(VSV-G). One representative dose response experiment is shown. e Combined data from four independent experiments, using a viral dose within linear range. Each symbol represents data from one experiment. **p < 0.01 (paired t test)