Figure 4.

Plasminogen binding to NA on the cell surface. (A) 293T cells were transfected with the WSN NA (WSN) gene, a mutant containing an alteration at the carboxyl-terminal residue, from lysine to arginine (K453R), or the HK NA gene and incubated for 24 h. Transfected cells were suspended in PBS containing 1% BSA and then incubated with 100 μg/ml human plasminogen. Bound plasminogen was detected by anti-human plasminogen antibody and fluorescein isothiocyanate-labeled anti-rabbit antibody. Cells were analyzed by flow cytometry. The thin line indicates control cells transfected with an expression plasmid with no insert, while the thick line refers to NA gene-transfected cells. (B) MDBK cells were infected with the WSN, WSN-HK, or WS virus. Twelve hours after infection, the cells were incubated with human plasminogen (10 μg/ml) and bound human plasminogen was detected as described above. MOCK, mock-infected cells.