Distribution of the attachment (G) glycoprotein and GM1 within the envelope of mature respiratory syncytial virus filaments revealed using field emission scanning electron microscopy

Field emission scanning electron microscopy (FE SEM) was used to visualize the distribution of virus-associated components, the virus-attachment (G) protein, and the host-cell-derived lipid, GM1, in respiratory syncytial virus (RSV) filaments. RSV-infected cells were labeled in situ with a G protein antibody (MAb30) whose presence was detected using a second antibody conjugated to colloidal gold. No bound MAb30 was detected in mock-infected cells, whereas significant quantities bound to viral filaments revealing G protein clusters throughout the filaments. GM1 was detected using cholera toxin B subunit conjugated to colloidal gold. Mock-infected cells revealed numerous GM1 clusters on the cell surface. In RSV-infected cells, these gold clusters were detected on the filaments in low, but significant, amounts, indicating the incorporation of GM1 within the viral envelope. This report describes the first use of FE SEM to map the distribution of specific structural components within the envelope of a Paramyxovirus.