Figure 4.

Cell–cell fusion activity of gB N-glycosylation site mutants. RK13 cells were cotransfected with 200 ng of the expression plasmids for enhanced green fluorescent protein (EGFP), PrV gH, gL, gD, gB wild-type (WT) or the indicated gB glycosylation site mutant. Cells transfected with EGFP and empty vector pcDNA-3 served as a mock control. 24 h post-transfection, syncytia formation was assessed. The number of syncytia in 10 fields of view was multiplied by the corresponding mean syncytia area to obtain the total fusion activity. Fusion activities were normalized to activities obtained with the four wild-type glycoproteins. Mean relative values from four independent experiments and corresponding standard deviations are shown.