FIG. 1.

Oral vaccination with MPL-based adjuvants does not prime effective immune responses. (A) Systemic immune responses as assessed from IFN-γ levels after in vitro restimulation of spleen cells from mice harvested 2 weeks after the booster vaccination. Results are IFN-γ levels (in picograms per milliliter) from four mice per experimental group ± standard deviations. (B) Protective efficacy as assessed by determining reductions in the numbers of CFU in the lungs of mice 6 weeks after aerosol infection. Results are mean log₁₀ numbers of CFU ± standard deviations from four mice per experimental group. Protection expressed as the log reduction in numbers of CFU in vaccinated versus naïve animals is shown above each group. sc, subcutaneous.