2.5 Data analysis
Based on the inhibition of virus growth, the half-maximal effective
concentration (EC50) of aprotinin was calculated using
the GraphPad Prism program (version 5; San Diego, CA, USA). This
procedure is commonly known as a logistic regression using the following
formula: Y = 1/1 + 10 ([logEC50 – logX] ×
Hillslope), where Y represents response (inhibition of virus growth),
and X represents the concentration of aprotinin. Hillslope is the
parameter to describe the steepness of the curve. The data analysis was
performed using GraphPad Prism for Windows, and differences were
evaluated by one-way ANOVA. P values less than 0.05 (P< 0.05) were considered statistically significant.