FIG 6.

Immunization of mice with the rAd5-YFV vaccine alone or in combination with rYFV provides protection against lethal primary aerosol and subsequent intranasal WT CO92 challenges. PreAd mice (n = 10) were i.n. immunized with 8 × 10⁹ v.p./40 μl of rAd5-YFV either alone or in the combination with 10 μg of rYFV (emulsified 1:1 in alum adjuvant) i.m. The immunizations occurred 2 weeks apart. PreAd mice injected with Ad5-Empty served as a negative control. After 15 days postimmunization, mice were first challenged with aerosolized WT CO92 at a Dp of 4.62 × 10⁵ CFU. At 32 days after the initial aerosol challenge, the surviving animals from the immunized groups along with five age-matched uninfected naive mice were infected with 100 LD₅₀ of WT strain CO92 luc2 by the i.n. route. (A) The deaths were recorded for the initial aerosol challenge and then the subsequent intranasal challenge, and the percentages of survival were plotted. The P values are in comparison to the control group for each challenge and are based on Kaplan-Meier curve analysis. (B) The animals were also imaged by IVIS for bioluminescence on day 3 after WT strain CO92 luc2 i.n. challenge. Panel I, infected naive mice as an i.n. challenge control. The rightmost animal in this panel is an uninfected image control. Panel II, animals immunized with the prime-boost strategy. Panel III, animals immunized with rAd5-YFV vaccine alone. The bioluminescence scale ranges from most intense (red) to least intense (violet).