This observation, together with the more efficient dissemination of Δvpu virus than wt virus from tetherinneg cells (Figure 5), suggests the faster replication of Δvpu virus in this setting (cell-to-cell spread) but not during the initial (cell-free) phase of infection, which proved not to be affected by Vpu, irrespective of the presence/absence of tetherin at the cell surface (Figure 3, B and 3C). This evidence concerns the gene BST2 and infection.