FIG 3.

Cell-cell fusion efficacy in the presence of canine N4 of H-A75/17 and derivative H-Y539A mutant viruses. Vero, Vero-cN4, and Vero-cSLAM cells were transfected with DNA plasmids encoding empty vector (pCI), H-A75/17 (Hwt), or H-Y539A along with F-A75/17 (Fwt) (A) or F-L372A (B). A plasmid encoding the red fluorescent protein was included to increase the sensitivity of the assay. Representative fields of view were captured at 24 h (or 48 h for the Hwt and F-L372A combination in Vero-cN4 cells) posttransfection with a confocal microscope (magnification, ×100; FluoView FV1000; Olympus). The white arrow indicates very limited induction of cell-cell fusion.