[The standardization of the methods for assessing the immunogenic activity of all of the components of an adsorbed DTP vaccine].

The reproducibility of laboratory methods, recommended by WHO and used by manufacturing and control institutions of most countries for the evaluation of the immunogenic potency of the pertussis, diphtheria and tetanus components of adsorbed DPT vaccine in the process of its production, was studied. This immunogenic potency was experimentally studied in comparison with the immunogenic potency of national standard samples from Bulgaria, Czechoslovakia, Hungary, Poland and Russia. The results of this study indicated that the coded commercial lots of adsorbed DPT vaccine corresponded to WHO requirements with respect to the immunogenic potency of all their components.

[Improvement in the laboratory methods of assessing the safety of the of the pertussis component of DPT vaccine adsorbed].

The mouse paw edema test and the tests for the determination of leukocytosis-stimulating and histamine-sensitizing activity are reproducible if standard samples are used and the properties under test are evaluated with reference to the characteristics of standard samples. The standard character of the weight gain test on mice is also enhanced if all conditions of the test are standardized. The most accurate information on the toxicity of the pertussis component of adsorbed DPT vaccine can be obtained if a single human dose (0.

[2-cycle culture of Vibrio cholerae in a fermenter].

The method for the two-cycle cultivation of V. cholerae, reference strains Inaba and Ogawa, in a fermenter has been developed. In the first and second cultivation cycles no difference in the yield of the biomass and in the ultrastructure of the vibrios has been established.

[Experience of the People's Republic of Bulgaria in controlling diphtheria, tetanus and whooping cough].

The analysis of the morbidity and mortality rates in diphtheria, tetanus and pertussis in Bulgaria after the introduction of the compulsory mass immunization of children with combined DPT vaccine is presented. These data indicate that morbidity in diphtheria, tetanus and pertussis has sharply decreased. Favorable results with respect to these three diseases are the consequence of the complete coverage of the child population by immunization with the vaccine whose quality has been steadily improving for the last 20 years.

[Standardization of cholera vaccine and preparation of a national reference standard].

The antigenic potency of the proposed national reference preparations in comparison with that of the corresponding international reference preparations was studied by means of the active protection test in mice. The antigenic potency of the proposed national reference preparations for Inaba and Ogawa was found to be the same or even greater than the antigenic potency of the international reference preparations for cholera vaccine. A high level of antigenic activity was observed during comparison of a production lot of cholera divaccine with the international reference preparation and the national reference preparation in parallel tests.