Abstract
Human respiratory syncytial virus (RSV) infection in human lung epithelial A549 cells induces filopodia, cellular protrusions consisting of F-actin, that extend to neighboring uninfected cells (Mehedi et al., 2016). High-resolution imaging via stimulated emission depletion (STED) microscopy revealed filamentous RSV particles along these filopodia, suggesting that filopodia facilitate RSV cell-to-cell spread (Mehedi et al., 2016). In this protocol, we describe how to fix, permeabilize, immunostain, and mount RSV-infected A549 cells for STED imaging. We show that STED increases resolution compared to confocal microscopy, which can be further improved by image processing using deconvolution software.