Fig. 4

CedV F glycoprotein-mediated fusion activity. Syncytium formation in a MDCK-2 and b Vero76 cells co-expressing CedV F and G proteins was visualized by Giemsa staining at 30 h p.t.. Magnification, × 20. n = 3; c Quantitative reporter gene assay. At 24 h p.t., Vero76 cells expressing the T7 polymerase were layered on the cells expressing the indicated glycoproteins and incubated for 3 h at 37 °C. After cell lysis, luciferase activity was measured. Samples were tested in duplicates in three independent experiments. Reporter activity measured for the parental CedV F protein co-transfected with CedV G protein was set to 1 serving as a reference point for fusion activity. Bars represent the fusion activities of the different (mutant) CedV F proteins in relation to the fusion activity of the parental protein and include the standard error of the mean (SEM). Statistical analysis: unpaired Student’s t-test with Welch’s correction; (*) p ≤ 0.05; (**) p ≤ 0.005