FIG. 3.

Bactericidal activity in serum samples and nasal washes of mice immunized three times with the different formulations shown in Table 1, containing the conjugated CRM-MenC vaccine (2.5 μg of oligosaccharide per dose) and the LTK63 mutant (1 μg per dose) with or without the SMBV (100 μg per dose). Bactericidal antibody titers from pooled serum samples taken before (pre) and after (post-1, -2, and -3) each immunization are shown. Bactericidal titers from individual serum samples did not differ from the data obtained with pooled samples (not shown). Results are expressed as the last dilution of the serum samples giving 50% bacterial killing. Bactericidal activity was also tested in nasal washes taken after the third immunization and pooled. Each pool was tested, starting from a 1:2 dilution. Considering the dilution factor inherent in the nasal wash, results are expressed as the actual numbers of surviving bacterial colonies.