Figure 3. Production of pertussis toxin (Ptx) and pertactin (Prn) by pertussis toxin promoter 1 (ptxP1) and ptxP3 strains. Strains were incubated for the 48, 54, and 60 h, after which the amount of Ptx and Prn was determined by ELISA. The production ratio was calculated as follows: ptxP3 strain values/ptxP1 strain values; 8 strains, 4 ptxP1 strains and 4 ptxP3 strains, were used. The experiment was performed 3 times. Error bars indicate 95% confidence intervals. The Ptx and Prn ratios were significantly different from 1 (p<0.0001 and 0.03, respectively).