FIG. 4.

Syncytium formation mediated by homotypic and heterotypic NiV and HeV envelope glycoprotein combinations. HeLa cells were infected with recombinant vaccinia viruses encoding either HeV F (A), NiV F (B), HeV F and HeV G (C), NiV F and NiV G (D), HeV F and NiV G (E), or NiV F and HeV G (F) (effector cells). Partner U373 cells were detached by using EDTA and washed three times with PBS. The effector cells (10⁵) were mixed with the U373 partner cells (10⁵) in duplicate wells of a 96-well plate and incubated at 37°C. After 18 h, photographs were taken at ×400 magnification.