Fig. 4.

FAC-induced fusion of influenza A virus or liposome. a PR8-infected A549 cells were treated with FAC at indicated time points post infection. Viruses were washed out at 3 h post infection and cells were analyzed for viral RNA at 12 h post infection through real-time PCR. b A549 cells and PR8 were incubated at 4 °C ± FAC for 1 h and cells were washed and analyzed for viral RNA through real-time PCR. c PR8-infected A549 cells were treated with or without FAC for 1 h. Cells were analyzed under confocal microscopy of PR8 NP protein. Scale bars, 20 μm. d PR8-infected A549 cells were treated in the presence or absence of FAC for 1 h. Cells were analyzed via electron microscopy. Arrows indicate endocytosing and endocytosed viruses in the PR8 panels (left, upper and lower images, scale bars: 0.2 μm). In the PR8 + FAC panels, upper image shows fusion viruses (right, upper panel, scale bar: 0.2 μm); lower image shows fusion viruses on the cell surface (right, lower panel, scale bar: 1 μm). e A549 cells and PR8 virus were incubated at 37 °C ± FAC for 3 h. Cells were washed and analyzed for viral RNA through real-time PCR. f PR8 in solution with or without FAC was incubated for 1 h at room temperature, centrifuged, and analyzed by negative-stain electron microscopy. g Liposome ± FAC were incubated for 1 h at 37 °C, stained with DiD (50 μM), and analyzed through bright field microscopy. Scale bars, 20 μm. h Hela cells were transfected by liposome and poly(dA:dT)-rhodamine mix ± FAC for 6 h. Cells were analyzed via confocal microscopy. Scale bars, 10 μm. Data are representative of three independent experiments. Error bars represent SD