FIG. 1.
Phenotypic characterizations, cytopathic effects, and titers of virus release of ED-tag, ED-V−, and Ed-V+ after infection of human glioblastoma U-87 cells (MOI of 0.1). (a) Cell extracts were harvested 40 h p.i. and the expression of N protein was adjusted to similar amounts as defined by Western blotting (lanes 1 to 3). Identical lysate amounts were then used to detect V protein expression (lanes 4 to 6). (b) U-87 cells were infected with ED-tag (MOI of 0.5) or ED-V+ (MOI of 5) for 16 h and labeled for 3 h and then were harvested immediately (lanes 1 and 4) or chased for 8, (lanes 2 and 5) or 16 h (lanes 3 and 6). A monoclonal MV N-specific antibody or a V-specific serum was used for immunoprecipitation, and the corresponding signals were quantified by phosphorimaging. (c to e) Syncytium formation in U-87 cells infected with ED-tag (c), ED-V− (d), or ED-V+ (e) 24 h p.i. (f) Supernatants of U-87 cells infected with ED-tag, ED-V−, or ED-V+ for 24 or 48 h were titrated in duplicate by standard plaque assays. Values shown are the means of three independent experiments.