FIG. 4.
Characterization of particles released from WT- and NS2Aα QST-transfected cells. BHK cells were transfected with WT or NS2Aα QST mutant (QST) RNA transcripts, metabolically labeled with [35S]methionine-cysteine from 14 to 26 h posttransfection, concentrated by pelleting, and resuspended in buffer as described in Materials and Methods. (A) Rate-zonal sedimentation. WT or NS2Aα QST mutant particles were sedimented in parallel glycerol gradients as described in Materials and Methods. (B) Equilibrium banding. A portion of pooled fractions 5 and 6 [WT (virus)] and a portion of pooled fractions 12 to 14 [WT (subviral)] from the glycerol gradient shown in panel A were loaded on parallel tartrate gradients. For the NS2Aα QST mutant (QST), fractions 12 to 14 were pooled and analyzed. (C) Infectivity of the gradient fractions. Fractions of the gradients shown in panel B were analyzed for infectivity by plaque assay on BHK cells. In all panels, fractions are numbered from the bottom to the top.