Synchronized Retrovirus Fusion in Cells Expressing Alternative Receptor Isoforms Releases the Viral Core into Distinct Sub-cellular Compartments
(A, B) Examples of the mean square displacement (MSD) as a function of time for GFP-tagged (green circles) and DiD-tagged (red circles) particles in TVA950 (A) and TVA800 (B) cells. Blue asterisks mark spatial separation of cores from membranes that coincided with an abrupt increase in the MSD slope for SVPs (green), while the movement pattern of DiD-recipient endosomes did not change significantly. (C) Representative MSD curves after SVP release are shown for five SVPs in TVA950 cells (black lines) and in TVA800 cells (red lines). (D) Log-log plot showing the mean MSD slopes and standard deviations for 15 SVP trajectories after core release in TVA950 (black) and TVA800 (red) cells each. (E) Distributions of diffusion coefficients for endosomes and viral particles before and after SVP release. Diffusion coefficients were calculated, as detailed in the Materials and Methods. Box plots together with the Gaussian distribution for the diffusion values (circles and solid lines) corresponding to 18 endosomes (“DiD post-fusion”, red circles) and SVPs (“GFP post-fusion”, green circles) after core release are shown for TVA800 and TVA950 cells. Diffusion coefficients of three SVPs that were judged to be released into endosomal compartments of TVA950 cells are colored black (under “GFP post-fusion”). For comparison, the motility of 10 non-fusogenic particles trapped in endosomes after perfusion with HBSS is shown (“GFP, no fusion”, yellow circles). In addition, the diffusion coefficients for 10 not fused particles in the presence of the inhibitory peptide R99 is shown (blue circles). The diffusion coefficients of endosomes tagged with YFP-Rab7 (n = 20) and CFP-Rab5 (n = 20) in TVA800 and TVA950 cells (pooled data) are shown by magenta and cyan triangles, respectively.