FIG 3.

Effects of vaccination and previous infection on colonization. Unvaccinated animals (n = 4), DTaP-vaccinated animals (n = 3), convalescent animals (n = 3), and animals vaccinated with DTwP (Triple Antigen, DT-COQ, or Quinvaxem; n = 2 per group) were directly challenged with B. pertussis. (A) Colonization was monitored by quantifying B. pertussis CFU per milliliter in biweekly nasopharyngeal washes with a limit of detection of 10 CFU/ml. The mean colonization is presented for each group and time point with error bars representing the SE. (B) For each animal, the time to clearance is defined as the first day that no B. pertussis CFU were recovered from nasopharyngeal washes. The mean time to clearance is shown for each group (same sizes as above except n = 3 for the unvaccinated group since one unvaccinated animal was not followed to clearance). Since no B. pertussis organisms were recovered from the convalescent animals, the mean time to clearance was defined as the first day of sampling (day 2, indicated by the dashed line). *, P < 0.01 versus naive.