FIG. 4.

Biotinylation of envelope glycoproteins expressed on the cell surface. Cells expressing radiolabeled glycoprotein were incubated with biotinylation reagent on ice. Following lysis and immunoprecipitation with patient serum to isolate viral proteins, pellets were boiled in SDS to denature antibody and biotinylated proteins were isolated by binding to streptavidin-agarose. The biotinylated viral proteins were then analyzed by SDS-PAGE (8% polyacrylamide).