Additionally, under unrestricted conditions (i.e., no tetherin expression and no agar overlay), VSV-GFP infection also became evident in cells that were not in direct contact with the central focus of infection (Fig. 1D; Movies S1 and S2, upper left panels), consistent with the notion that some cells become infected via diffusion of virions in the extracellular culture medium. Here, BST2 is linked to infection.