Virus infection
Mouse-adapted A(H1N1)pdm09 (strain: A/Narita/1/09) or seasonal H1N1
(strain: A/Puerto Rico) viruses were provided by the National Institute
of Infectious Diseases (Tokyo, Japan). On day 31, influenza virus
(concentration: 1×105 pfu/20 μL) or vehicle
(mock-infection) was administered intranasally to the mice. The number
of mice in each group ranged from 4 to 7.