Fig 2.

Cleavage of A/Beijing/718/2009 influenza virus HAs by human plasmin. (A) Human plasmin-dependent HA cleavage of A/Beijing/718/2009 (Bei718) HA and Bei718 HA-328S. Surface biotinylation was performed on 293T cells expressing each HA. Transfected cells were treated with human plasmin (100 mU/ml) at the indicated times, and the cleavage product(s) was detected by Western blot analysis using anti-HA antibody. (B) Quantification of the time-dependent human plasmin-mediated HA cleavage efficiency of Bei718 HA and Bei718 HA-328S. The error bars represent the standard deviations of the results of three independent experiments. Statistical analyses were performed using Student's t test (unpaired, one tail) by GraphPad Prism, comparing the individual treatment times (*, P < 0.05; **, P < 0.005; ***, P < 0.0001).