FIG. 3.

Cell fusion and infectivity complementation of gH_HR-EL. (A) Quantification of luciferase-based cell-cell fusion assay in COS and BHK cells expressing the indicated gH plasmid plus gD, gB, and gL. Luciferase activity was expressed as relative light units (RLU). Each experiment was performed at least three times, and samples were run in triplicate; mean values are shown. Vertical bars, standard errors. (B) Infectivity complementation. The indicated cells were transfected with plasmids encoding wt gH or gH_HR-EL and were infected 4 h later with a gH^−/+ stock of SCgHZ (7 PFU/cell). Progeny virus was titrated at 24 h in gH-expressing cells. Each experiment was performed twice. The mean values of a typical experiment are shown. Vertical bars, standard errors. (C) gH_HR-EL is incorporated into complemented virions. Extracellular virions from the experiment for which results are shown in panel B were pelleted by high-speed centrifugation, subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose membranes, and visualized by Western blotting with MAb H12 against gH and MAb H170 against gD, followed by anti-mouse peroxidase and ECL. The numbers to the left are the migration positions of molecular mass markers (in kilodaltons).