Synchronized Retrovirus Fusion in Cells Expressing Alternative Receptor Isoforms Releases the Viral Core into Distinct Sub-cellular Compartments
(A) Schematic diagram of the NH4Cl arrest/chase experiments. EnvΔCT/BlaM-Vpr pseudoviruses were bound to either TVA950 (B) or TVA800 (C) cells at 4°C. Cells were allowed to internalize virus during 45 min at 37°C in the presence of 70 mM NH4Cl (yellow line in A). Fusion was initiated by transferring the cells into HBSS supplemented with 50 µg/ml R99 (blue line in A) for varied times and stopped either by adding back NH4Cl containing 50 µg/ml R99 (black circles) or by placing the samples on ice (TB) (red circles). At the end of the chase, cells were chilled on ice, loaded with the BlaM substrate and incubated overnight at 12°C. Data points are means and SEM of combined triplicate measurements from two independent experiments.