FIG. 1.

Impact of five single amino acid changes on wild-type H protein function. Vero/hSLAM and H358 cells were cotransfected with expression plasmids encoding GFP, IC323-F, and IC323-H or the corresponding mutants. (Top) SLAM-dependent fusion support on Vero/hSLAM cells. (Center) EpR-dependent fusion support on H358 cells. Fusion was graded as indicated in the Materials and Methods section, based on the average of three independent experiments; identification of syncytia was facilitated by the combination of phase-contrast analysis and observation of GFP expression. (Bottom) H protein expression levels in H358 cells at 24 h posttransfection of the corresponding plasmids. H protein was visualized by immunoblotting using an antibody directed against the cytoplasmic tail of H (3).