FIG. 5.

Quantitation of cell fusion mediated by homotypic and heterotypic NiV and HeV envelope glycoprotein combinations. HeLa or 3T3 cells were infected with recombinant vaccinia viruses encoding various combinations of the envelope glycoproteins HeV F, HeV G, NiV F, NiV G, MeV F, MeV H, CDV H, and CDV F, along with a recombinant vaccinia virus encoding T7 RNA polymerase (effector cells). HeLa cells were used as effector cells for expression of HeV and NiV G envelope combinations, and 3T3 cells were used as effector cells for expression of MeV and CDV HA envelope combinations. TK⁻, U373, and 3T3 target cells were infected with the reporter vaccinia virus vCB21R encoding E. coli lacZ (target cells). Glycoprotein-expressing cells (10⁵) were mixed with each target cell type (10⁵) in duplicate wells of a 96-well plate. After 3 h at 37°C, Nonidet P-40 was added and β-Gal activity was quantitated. Key: no target cells, level of background β-Gal activity in effector cell populations alone. The level of background β-Gal activity in target cell populations alone is labeled “target cells” on the x axis, and that from target cells mixed with effector cells infected only with a vaccinia virus encoding T7 RNA polymerase is labeled “none.” (A) HeV and NiV envelope combinations; (B) MeV and CDV envelope combinations; (C) henipavirus and morbillivirus envelope combinations.