Figure 2From: Identification of a new amino acid mutation in the HN protein of NDV involved in pathogenicityBiological activities of the original HNs. The expression of each HN protein at the cell surface was determined by A IIFA and FCM B analysis at 24 h post-transfection of BHK-21 cells by using a primary HN monoclonal antibody and a fluorescein-labelled secondary antibody. Empty cells were used as mock cells, and empty pCAGGS was used as the negative control. C The HAd activity was determined based on the ability of HN expressed at the cell surface at 16 h post-transfection to adsorb chicken erythrocytes at 4 °C. D NA activity was determined as the ability of the cell surface HN proteins to catalyse the release of sialic acid at 16 h post-transfection. All marks indicate significance in comparison to HN-CE16 (100%), and the results are presented as the mean ± SD of the results of three independent experiments. *p < 0.05, **p < 0.01.Back to article page