TABLE 1

Outcome of immunized mice after live intranasal F. tularensis Schu S4 challenge

Immunization typeaImmunization routebSurvival 14 days postchallengeTime to death postchallengec
No. of survivors/total no. (%)PdAvg ± SD (days)Pe
V (control)i.p./i.p., i.p./i.n., i.n./i.p./i.n.0/34 (0)4.9 ± 0.3
F. tularensis Schu S4-Vi.p.0/5 (0)NS6.4 ± 0.9<0.01
i.p./i.p.1/10 (10)NS6.8 ± 1.0<0.001
i.p./i.n.7/35 (20)0.0116.1 ± 0.9<0.001
i.n./i.p.2/8 (25)0.0336.3 ± 1.0<0.01
i.n./i.p./i.n.2/9 (22)0.0407.0 ± 0.8<0.001
i.n./i.n.0/11 (0)NS5.5 ± 0.5NS
i.n./i.n./i.n.3/15 (20)0.0255.9 ± 0.8<0.001
s.c./i.p., s.c./i.n., s.c./s.c.0/30 (0)NS5.7 ± 0.7<0.001
  • a Mice were immunized with control vesicles (V) or Schu S4-V at 2-week intervals by the indicated routes. Two weeks after the final immunization, all mice were challenged with ∼20 CFU (ranging from 3 to 49 CFU in different experiments) of F. tularensis Schu S4 by the intranasal route.

  • b i.p., intraperitoneal; i.n., intranasal; s.c., subcutaneous.

  • c Mean and standard deviation of time to death were calculated from only those animals that succumbed to infection.

  • d Fisher's exact test, P value compared to that of control; NS, not significant.

  • e One-way ANOVA, P value of Tukey posttest compared to that of control.