FIG. 1.

Competitive index analysis of the reference strain and wild-type 10403S L. monocytogenes. Groups of 3 to 10 naive or L. monocytogenes-immunized mice were infected with a 1:1 mixture of DP-L3903 and 10403S. CD-1 mice were sacrificed 48 h postinoculation, while BALB/c and C57BL/6 mice were euthanized after 60 h. A competitive index of 1 indicates that the two strains are proliferating equally in vivo. Abbreviations: S, spleen; L, liver. 1°, infection of naive mice; 2°, infection of L. monocytogenes-immunized mice; y axis, competitive index.