Fig 11.
Cysteine 123 in the NDV HN globular head alters neuraminidase and fusion promotion. (A) Schematic diagram of chimeric protein G1-186-HN123-571 constructs. (B) FACS analysis of cell surface expression from cells transfected with the chimeric proteins shown in panel A. The results are presented as percentages of NDV HN cell surface expression. (C) Receptor binding in the absence (□) or presence (■) of 2 mM zanamivir. (D) Neuraminidase activity of the receptor binding proteins, expressed in relative fluorescence intensity units (RFU) in the absence (□) or presence (■) of 2 mM zanamivir. The values in panels B, C, and D are means ± the SD of results from samples assessed in triplicate and are representative of the experiment repeated at least three times. (E) Cell-to-cell fusion promoted by the chimeric proteins expressed with NiV F was observed in the top panel by syncytium formation using visible microscopy and in the bottom panel by redistribution of RFP (red fluorescent protein) using fluorescence microscopy.