Influenza Challenges
Four weeks after immunization, the mice were challenged intranasally
with mouse-adapted influenza A/Puerto Rico/8/34 (PR8; H1N1). Groups of
10 mice were challenged intranasally (i.n.) on day 28. The mice were
anesthetized intraperitoneally with ketamine/xylazine (2 mg ketamine and
0.15 mg xylazine) before i.n. infection with 10 µL of sterile saline
containing PR8 (20 HAU/mouse). The protective efficacy of the
immunization was measured by survival up to 14 days and mice that lost ≥
25% of their initial body weight was euthanized according to
institutional guidelines.