Figure 4.

Immunized DBA/2J mice did not lose body weight and survived lethal infection with human 2009 pandemic influenza A virus. Female DBA/2J mice were immunized by i.m. injection of 2 × 10⁵ FFU HA04 virus in 20 μl PBS. Injections were repeated after 14 days. Immunized and naïve female DBA/2J mice were infected with 2 × 10³ FFU HA04 virus. Body weight loss for each group of infected mice at various days p.i. (time post infection) is shown with reference to the starting weight (body weight [%]). In addition to mice that were found dead, mice with a weight loss of more than 30% of the starting body weight were euthanized and recorded as dead. Data represent mean values +/- SEM.