Membrane staining of cells resulting from fusion with fluorescently labeled VLPs. DFJ-8 cells were incubated on chambered coverslips coated with VLPs (corresponding to 500 ng p24) labeled with MA.mCherry carrying the indicated Env derivatives: (A) Env.YFP; (B) Env.YFP.H8R; (C) Env.YFP.PR(-). Cells were fixed 2 and 30 minutes after virus-cell contact, respectively, and z-stacks were recorded. Maximum projections of deconvolved z-series are shown. White lines indicate the outline of the cell as determined by bright-field microscopy. Scale bars correspond to 10 μm.