Fig. 4.
Mice immunized with NBS-SecA2 L. monocytogenes are not protected against secondary infection with wt bacteria. Mice (four or five per group) were immunized with 0.1× the LD50 of the indicated bacteria (wt, 2 × 103; Del-SecA2, NBS-SecA2, and NBS-SecA2-FLAG, 106) or injected with PBS. One month later, mice were given a secondary challenge with 3 × 105 wt bacteria and killed 48 h after the challenge infection. Data show the number of bacteria in the spleen and the liver for each individual mouse and represent pooled results from two experiments. P values were calculated between groups of mice immunized with wt versus NBS-SecA2 and NBS-SecA2-FLAG L. monocytogenes and PBS versus Del-SecA2 and NBS-SecA2 L. monocytogenes in the experiment shown. P values close to 0.05 have low statistical significance.