Figure 4

Biological characteristics of rescued rCE16-HNA430T and rCE16. A Representative plaque formation induced by viral infection of BHK-21 cells. Monolayer cells were fixed with 4% paraformaldehyde and stained with crystal violet. The fusion indices were determined by measuring the plaque diameters (n = 10). B The relative HAd ability and NA activity were assessed for 1 MOI virus-infected BHK-21 cells. C The expression of HN proteins was detected by IIFA. BHK-21 cells were infected with virus at an MOI of 0.01 for 24 h. The cells were then incubated with a primary HN monoclonal antibody and a fluorescein-labelled secondary antibody and then photographed under a fluorescence inverted microscope with 100-fold magnification, Bar = 100 µm. The mock cells were empty cells incubated with the primary antibody and secondary antibody. Anti-HN(–) indicates infected cells incubated only with the secondary antibody. D Growth kinetics of rCE16-HNA430T and rCE16 in DF-1 cells treated with an MOI of 0.01. All marks indicate significance in comparison to rCE16 (100%), and the results are presented as the mean ± SD of the results of three independent experiments. *p < 0.05, **p < 0.01.