FIG 3.

Cell-cell fusion activity of gH truncation mutants and transcomplementation of PrV-ΔgH. (A) RK13 cells were cotransfected with 200 ng of expression plasmids for EGFP in combination with full-length gB, gL, gH, or C-terminally truncated gH. Twenty-four hours posttransfection, the areas of green fluorescing syncytia were measured, and total fusion activity was determined by multiplication of the mean syncytium area with the number of syncytia in 10 fields of view. Fusion activities obtained with wild-type gH Ka, gB, and gL were set as 100%. Cells transfected with empty vector pcDNA3 served as a negative control (vector). Shown are mean relative values and standard deviations from four independent experiments with the corresponding standard deviations. Values significantly differing from those obtained with gH Ka are marked (**, P < 0.01; ****, P < 0.0001; all by unpaired t test with Welch correction). n.s., not significantly different from gH Ka. (B) gH Ka- or mutant gH-expressing RK13 cells were infected with PrV-ΔgH. Progeny virus titers were determined on wild-type PrV gH/gL-expressing cells and are given in PFU per ml. Cells transfected with the empty vector pcDNA3 served as a negative control. Shown are mean values for three independent assays with corresponding standard deviations. n.s., not significantly different from gH Ka.