Cross-protection of H5N1-M2e-MAP-vaccinated mice against lethal challenge of pandemic 2009 H1N1 virus. H5N1-M2e-MAP-vaccinated mice were challenged with lethal dose (10LD50) of heterosubtypic H1N1 virus A/Beijing/501/09 strain and monitored daily for 2 weeks post-challenge. (A) Percentage change (%) of mouse body weight. Each point represents mean body weight of 10 mice per group. (B) Survival rate (%). The significant differences (P < 0.001) of H5N1-M2e-MAP plus Freund's adjuvant versus Freund's adjuvant is indicated as *, while H5N1-M2e-MAP plus aluminum adjuvant versus aluminum adjuvant is indicated as **.