Figure 6: Protection against lethal challenge.

Groups of mice immunized twice with the indicated VLPs (or PBS) were challenged intranasally with a lethal dose of influenza virus A/PR/8/34 (5 LD50). (a) Morbidity was assessed by daily monitoring body weight for two weeks. Values represent the mean weight of each group expressed as a percentage of the initial weight on the day of inoculation (100%). Error bars show the standard error of the mean. (b) Survival was monitored for 14 days and is expressed as the percentage of surviving mice.