Determination of the epinephrine-refractory hypoglycaemic activity of whole-cell pertussis vaccine in mice

A new assay method has been developed for the quantitative estimation of the inhibitory effect of pertussis vaccine on epinephrine-induced hyperglycaemia in mice. The statistical analysis of the assay was based on logarithm-transformed estimates of the blood glucose levels. The method was sufficiently sensitive to detect the activity of 0·004 millilitre of commercial combined diphtheria-tetanus-whole cell pertussis vaccine. The estimated common variance was as small as 0·0034 and the assay was highly reproducible. Among commercial vaccines there was a significant difference in activity. The activity of a stock pertussis vaccine was inactivated by 5 mm glutaraldehyde at 37 °C for 30 min, but resisted treatment with 40 mm formaldehyde at 37 °C for 5 days. The extent of inactivation with the chemicals was calculated by a parallel line assay as the activity relative to that of untreated control pertussis vaccine.