FIG 2.
Protection conferred by immunization with the recombinant adenoviruses in mice that had preexisting immunity to adenovirus. To establish preexisting immunity to adenovirus, naive mice (n = 40) received a single dose (8 × 109 v.p./100 μl) in both quadriceps (50 μl each) of Ad5-Empty by i.m. injection at 30 days prior to vaccination. Naive mice receiving saline served as a control. Subsequently, mice were i.n. immunized with one dose (8 × 109 v.p.) of rAd5-LcrV or rAd5-YFV vaccine. Animals received the same dose of Ad5-Empty by i.n. instillation and served as a negative control. These mice were then divided into two sets and challenged on day 15 postimmunization either subcutaneously (s.c.) with 24 LD50 (A) or intranasally (i.n.) with 21 LD50 (B) of the WT CO92. The P values are in comparison to the negative-control group and are based on Kaplan-Meier curve analysis. Mice were also bled prior to the challenge to evaluate IgG antibody titers, titers to its isotypes, and IgA to LcrV by ELISA (C). The P values are in comparison to the indicated groups and are based on two-way ANOVA with Tukey's post hoc correction. The asterisks indicate statistical significance compared to the control (Ad5-Empty) mice for IgA levels by using multiple Student's t test with the Holm-Sidak post hoc test correction.