FIG. 1.
Recombinant vectors and expression of HIV-1 envelope glycoproteins. (A) A schematic representation of rSFV vectors expressing the YU2gp120 and YU2gp140(-/GCN4) envelope glycoproteins is shown. The envelope genes are inserted downstream of the SFV nonstructural proteins (Replicase). The location of the SFV subgenomic promoter is indicated by an arrow. (B) Pulse-chase analysis of [35S]methionine-labeled BHK-21 cells infected with rSFV-YU2gp120 or rSFV-YU2gp140(-/GCN4) particles. Total labeled proteins at the different chase time points (0.5, 2, and 6 h) in cell lysates (left panel) and in TCA-precipitated supernatants (right panel) were separated by SDS-PAGE, and the proteins were visualized by autoradiography. (C) Supernatants from BHK-21 cells infected for 24 h with rSFV-YU2gp120 or rSFV-YU2gp140(-/GCN4) were immunoprecipitated with MAb IgGb12 and protein G Sepharose and eluted in SDS-PAGE sample buffer containing 2% BME, and the proteins were analyzed by SDS-PAGE and silver staining.