FIG. 3.

Sucrose gradient sedimentation profile and electron microscopy of Δγ381 particles. (A) Monolayers of Drosophila cells (approximately 1.2 × 10⁸ cells) were transfected with wt RNA1 and Δγ381 RNA2, as described in Materials and Methods. After 24 h, cells were lysed and virus particles were pelleted through a 30% (wt/wt) sucrose cushion. The resuspended pellet was layered on a linear 10 to 40% (wt/wt) sucrose gradient and centrifuged at 274,000 × g for 1.5 h at 4°C. The gradient was fractionated with continuous absorbance at 254 nm. OD, optical density. (Inset) Electrophoretic analysis of proteins in the peak fraction and comparison with wt FHV. Gamma peptide migrated off the gel under the conditions used. Proteins were stained with Coomassie brilliant blue. (B) Electron micrograph of negatively stained, gradient-purified Δγ381 particles. Arrows indicate aberrant structures. Bar, 100 nm.