Researchers studying viral entry have not been able to visualize exactly how a viral particle fuses with a cell. We've developed a method whereby the different stages of fusion can be detected by the release of different fluorescent tags.
We inserted blue dye into the viral membrane so that at the moment fusion occurs, these dye molecules escape into an artificial membrane sheet, throwing off a bright burst of green light. Next, the inner leaflet of the viral membrane fuses with the lower leaflet of the membrane sheet creating a pore, which releases the red dye from the viral particles when fusion is complete.