FIG. 4.

Systemic anti-spore IgG responses. Groups of six mice were inoculated (arrows) orally with 10⁹ spores of probiotic strains of Bacillus, including Biosubtyl^NT (•), Enterogermina (▴), Subtyl (Δ), Bactisubtil (▪), and Biosubtyl^DL (□). A laboratory strain of B. subtilis (PY79) was also included (○). Individual samples were tested by indirect whole-spore ELISA for spore-specific serum total IgG. Naïve groups gave basal responses for all strains, and a representative line (anti-PY79) (⋄) is shown. For each animal, the end point IgG titer was calculated by determining the dilution of serum that produced the same optical density as the 1/40 dilution of the preimmune serum. The data are arithmetic means, and the error bars indicate standard deviations.