Vaccine containing M2e protein showed a reduction in viral load during the course of influenza A virus infection. BALB/c mice (9 heads/group) were infected with A/chicken/Korea/ma163/04 (ma163/H9N2), A/aquatic bird/Korea/maW81/05 (maW81/H5N2), or A/Philippines/2/82 (Phil82/H3N2) influenza virus at 2LD50 per mouse. Mice were sacrificed 3, 5, or 7 days post-challenge and samples were collected for lung virus titer. Lung (A) ma163/H9N2, (B) maW81/H5N2, and (C) Phil82/H3N2 influenza virus titers were detected at 3, 5, and 7 days post-challenge. The data are presented as GMT ± SD of 3 mice per group. † indicates p < 0.01 compared to the control group; ‡, p < 0.001 compared to the control group; §, p < 0.05 relative to the control group; mice died are indicated by *. The lower limit of detection (0.75 log10TCID50) is indicated by a dotted line.