抄録
In order to confirm the data reported in the previous papers, variously prepared pertussis vaccines were employed in the present investigation. Pertussis organisms grown either on α solid or in a liquid semi-synthetic medium were treated by: (1) heating at 56C for 30min, (2) storage in 0.1% formalin at 37C for 5 days, (3) storage in 0.1% formalin at 25C for 5 days, and (4) simple addition of sodium ethyl-mercuri thiosalicylate (merthiolate) as a preservative. Freeze-dried vaccines were made from these preparations four and a half months later. Mice were immunized intraperitoneally and challenged intracerebrally with a virulent strain of Bordetella pertussis 10 or 17 days later. The data were analyzed statistically assuming the probit corresponding to the percentage of survivors at any dose be a linear function of the logarithms of the dose. The 50% effective doses (ED50) and slopes of each vaccine were found to be uniform. More accurate estimates of ED50 were obtained by employing a pooled slope in each experiment. From these ED50 values, the relative potency was estimated by comparing the value of a vaccine to that of a dried merthiolate-vaccine. For vaccines derived from solid cultures, with an immunization period of 17 days, the relative potency of the vaccine heated at 56C was 0.63 (95% fiducial limits=0.52 to 0.76); the value for the formalinized vaccine at 37C was 0.40 (0.30 to 0.53) and one at 25C was 0.51 (0.34 to 0.77). Vaccines derived from liquid cultures showed a relative potency of 20 to 50% less than that of corresponding vaccine derived from α solid culture. The potency obtained for the 17 day immunization period was usually higher than that for the 10 day period. Using the overallpooled slope, an experimental design which will be appropriate for statistical analysis is discussed.
