Fig 9. Immunization with emrA1-mAb complexes using a prime-boost vaccination regimen or a low dose immunization improves the extent of protection against Ft SchuS4 challenge.

(A) C57BL/6 mice (n = 10 per group) were immunized i.d. with 1×10⁶ CFU of the emrA1 mutant-mAb immune complex and boosted i.n. on day 21 with a similar dose. On day 42 of the primary immunization mice were challenged i.n. with 17 CFU of Ft SchuS4. Age matched unvaccinated mice challenged with a similar dose of Ft SchuS4 served as controls. (B) C57BL/6 mice (n = 10 per group) immunized i.n. with 1×10⁶ CFU of the emrA1mutant-mAb immune complex and boosted i.d. on day 21 with a similar dose. On day 42 of the primary immunization mice were challenged i.n. with 17 CFU of Ft SchuS4. Age matched unvaccinated mice challenged with a similar dose of Ft SchuS4 served as controls. (C) C57BL/6 mice (n = 10 per group) immunized i.n. with 1×10³ CFU of the emrA1 mutant and boosted i.d. on day 21 with a similar dose. On day 42 of the primary immunization mice were challenged i.n. with 17 CFU of Ft SchuS4. Age matched unvaccinated mice challenged with a similar dose of Ft SchuS4 served as controls. (D) C57BL/6 mice (n = 10 per group) immunized i.d. with 1×10³ CFU of the emrA1 mutant and boosted i.n. on day 21 with a similar dose. On day 42 of the primary immunization mice were challenged i.n. with 17 CFU of Ft SchuS4. Age matched unvaccinated mice challenged with a similar dose of Ft SchuS4 served as controls. The survival results are expressed as Kaplan-Meier survival curves and P values were determined by Log-rank test.