| Abstract: | On the basis of the experimentally established dependence of the degree of binding of diphtheria toxoid with standard diphtheria antitoxin on the duration of their joint incubation with the maximum binding occurring in 3-4 hours of incubation at 37 degrees C, the method of the in vitro determination of the antigenic activity of diphtheria toxoid in liquid and adsorbed preparations is proposed. The method is based on the principle of double binding with the use of diphtheria antigenic (toxoid) erythrocyte diagnosticum. The antigenic activity of diphtheria toxoid, evaluated by the degree of its maximum binding with diphtheria antitoxin, correlated with its antitoxin-binding activity in animal experiments and did not correlate with its flocculating activity. The antigenic activity of diphtheria toxoid in adsorbed preparations, evaluated by their maximum binding with standard diphtheria antitoxin, was shown to be closely related to the immunogenic potency of these vaccines in animals. |
