2.4 Mouse experiments
All animal experiments were conducted in biosafety level 2-plus
facilities at the Korea Research Institute of Bioscience and
Biotechnology (Daejeon, South Korea). General animal care was provided
as required by the Institutional Animal Care and Use committee. Six- to
eight-week-old C57BL/6 mice were purchased from Koatech (Pyeongtaek,
South Korea), and ten mice per group were used. The mice were inoculated
via intranasal instillation with 3 times the 50% lethal dose (3
LD50) of the PR8 virus. The following day, the mice were
treated intravenously with aprotinin (2 mg/kg/day), orally with
oseltamivir (10 mg/kg/day), or intravenously with PBS (negative control)
twice a day for 5 days. The mice were monitored daily for 14 days for
weight change and mortality.