FIG 6.
Protection conferred by passive serum transfer. Naive BALB/c mice were i.p. injected with 500 μl serum from AdC68-F3M2e(H1-H5-H7)- or AdC68-F3M2e(H1-H7-H5)-immunized mice 1 day before infection with 5 LD50 of PR8 (AdC68-F3M2e(H1-H5-H7) (n = 5), AdC68-F3M2e(H1-H7-H5) (n = 5), or AdC68-empty (n = 11) or injection of PBS (n = 12). AdC68-empty- and PBS-treated groups served as controls. Mice from each group were monitored for 14 days for survival rates (a) and weight loss (b). Mean weights ± SD were determined at each time point. The chi-square test was applied to compare survival rates. One mouse in the AdC68-F3M2e(H1-H7-H5) group survived the challenge, but its weight loss was not included in the data in panel b corresponding to the time period after day 10. The experiments described above were repeated twice.