Septins are only recruited by CEV on the cell surface. (A) Representative immunofluorescence image showing the association of SEPT7 with CEV (yellow arrows) detected with the B5 antibody before membrane permeabilization in HeLa cells infected with WR expressing A3-RFP (virus) for 8 h. (B) Video stills showing GFP-SEPT6 (SEPT6) recruitment to an extracellular virus detected with the Alexa Fluor 488–conjugated B5 antibody (B5; yellow arrows) in live cells. The time in seconds is indicated. See Video 1. (C) Representative Airyscan confocal immunofluorescence image showing the association of SEPT7 (green) around CEV (red) in HeLa cells infected with WR expressing A3-RFP for 8 h. Bars: (A and B) 2 µm; (C) 3 µm (large upper image), 1 µm (lower medium-sized boxed images), and 300 nm (right small boxed images).