Determination of the antigenic activity of diphtheria anatoxin in liquid and sorbed preparations using an erythrocyte diphtheria antigen (anatoxin) diagnostic agent

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.     

Variants in the immune response to revaccination with diphtheria anatoxin in adults

The immunological effectiveness of the revaccination (made in two injections) of 488 adults aged 18-67 years with diphtheria-tetanus toxoid is discussed; the parallel study of the results of this revaccination was carried out in the diphtheria toxin neutralization test on Vero cells and in the passive hemagglutination (PHA) test. The specific features of the dynamics of the increase of diphtheria antitoxic antibodies, depending on the initial immunity level, the age and the sex of revaccinated persons, were determined. Among persons with the low level of circulating antibodies before revaccination four variants of immune response to the injection of diphtheria toxoid were registered: variant 1--rapid reaction like in secondary immune response (53.6%); variant 2--delayed but effective reaction like in primary immune response (27.3%); variant 3--slow weak response (6.5%); and variant 4--the absence of effective immune response to immunization made in 2-3 injections (12.6%). The immunological and neutralizing properties of diphtheria antitoxic antibodies in the process of immunization made in 2 injections were evaluated. Persons with abnormal immune response (variants 3 and 4) produced defective antibodies, displaying immunological activity in the PHA test, but in most cases unable to neutralize diphtheria toxin in vitro when tested on Vero cells.     

The specific prophylaxis of diphtheria in adults with adsorbed DT-m anatoxin]

The dependence of immune response on commonly observed immunity characteristics prior to immunization has been established on the basis of the study of the kinetics of immune response in adults receiving injections of adsorbed diphtheria-tetanus (DT) toxoid with reduced antigen content, both for routine immunization and on epidemiological indications. The necessity of the practical use of immunological screening for the differentiated approach to the choice of a suitable preparation (adsorbed diphtheria toxoid, adsorbed DT toxoid or adsorbed DT toxoid with reduced antigen content) and immunization schedule for adults, especially in epidemic foci, has been substantiated.