Evidence that the cell glycocalyx envelops respiratory syncytial virus (RSV) particles that form on the surface of RSV-infected human airway cells.

We examined how respiratory syncytial virus (RSV) particles circumvent the overlying glycocalyx on virus-infected A549 cells. The glycocalyx was detected using the lectin WGA-AL488 probe, and the antibodies anti-HS and anti-syndecan-4 that detect heparin sulphate (HS) and the syndecan-4 protein (SYND4) respectively. Imaging of RSV-infected cells provided evidence that the glycocalyx envelopes the virus filaments as they form, and that components of the glycocalyx such as HS moieties and SYND4 are displayed on the surface of the mature virus filaments. Using recombinant expression of the G protein we also demonstrated that the G protein was trafficked into pre-existing filamentous cellular structures with a well-defined glycocalyx, suggesting that the glycocalyx is maintained at the site of virus particle assembly. These data provide evidence that during RSV particle assembly the virus filaments become enveloped by the glycocalyx, and that the glycocalyx should be considered as a structural component of RSV particles.