FIG. 2.

Mucosal vaccination with influenza B virus vaccine fails to protect against lethal influenza A virus challenge. Groups of BALB/c mice received three i.n. inoculations of 20 μg of formalin-fixed H3N2 or B/Harbin/7/94 virus in the presence or absence of 2 μg of LT(R192G). An additional group of mice received three s.c. inoculations of 20 μg of fixed H3N2 virus together with 2 μg of LT(R192G). Two weeks after the final vaccine boost, mice were challenged i.n. with a lethal dose of H5N1 virus and monitored for survival (A) or euthanatized 5 days later for collection of lung and nose tissue (B). An asterisk indicates the vaccinated group was significantly (P < 0.05) different from the adjuvant-only control group by analysis of variance.