Fig. 2From: Two mutations in the HR2 region of Newcastle disease virus fusion protein with a cleavage motif “RRQRRL” are critical for fusogenic activityEffect of different regions of the F* protein on membrane fusion. a Induction of syncytium formation by different regions between F48-F* and La-F* in BHK-21 cells when co-transfected with F48-HN. Schematic diagram of each construct with substituted regions in F48-F* is shown at the top of each picture. b Quantitative analysis of syncytia in (a). c Identification of region 449–499 of HR2 in triggering syncytium formation. d Quantitative analysis of the syncytia in (c). Statistical significance is designated with lowercase letters (P < 0.05) or capital letters (P < 0.01)Back to article page