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Adsorbed DPT vaccine and adsorbed DT toxoids with normal and reduced antigen content were used for the immunization of rabbits. The levels of IgM and IgG and the dynamics of antibodies to diphtheria and tetanus toxins and to Bordetella pertussis in the blood sera of the animals were studied in the postvaccinal period (on days 15 and 34). This study revealed that the reduction of the antigen content of adsorbed DT toxoid to 5 Lf of diphtheria toxoid and 5 binding units of tetanus toxoid did not decrease the capacity of the preparation for increasing the levels of IgG and IgM, antibodies to diphtheria and tetanus toxins in the sera of the rabbits. The reduced content of these toxoids in adsorbed DPT vaccine did not affect its capacity for inducing the enhanced synthesis of IgG, antibodies to diphtheria and tetanus toxins, while the production of IgM and IgA remained unchanged. At the same time an increase in the titers of antibodies to B. pertussis in the animals was less pronounced than that observed after the injection of commercial adsorbed DPT vaccine. Additional investigations are necessary in order to establish the protective potency of the pertussis component in adsorbed DPT vaccine with the reduced content of toxoids and to find out the optimum antigenic composition for this preparation.

Antibody diagnosticum to pneumococci (serovar 3) has been prepared. The analysis of different antigenic preparations of pneumococci (serovars 1,3 and 6B) and the filtrates of culture fluid obtained in the process of the cultivation of bacteria belonging to serovars 3,9N and 23F has been carried out by means of the indirect hemagglutination test. The new diagnosticum has proved to be type-specific. This diagnosticum can be used for the evaluation of the quantitative content of specific polysaccharide in different antigenic preparations of serovar 3 pneumococci, as well as for the determination of the content of specific polysaccharide directly in the culture fluid, which constitutes a step in the determination of the period of the maximum synthesis of polysaccharide, necessary for the optimization of the process of the cultivation of pneumococci.

An extended controlled epidemiological trial was carried out for the purpose of studying the reactogenic properties, immunological and epidemiological efficacy of immunization against whooping cough, diphtheria and tetanus according to a scheme suggested by the authors (AKdeltaC-AKdeltaC-KB) in comparison with the official scheme (AKdeltaC-AKdeltaC-AKdeltaC). There was revealed some increase in the frequency of general reactions in children vaccinated by the experimental scheme; however strong general reactions and local reactions of different intensity were encountered with equal frequency in both groups. Two months after the end of the vaccination significantly higher titres of pertussis agglutinins were revealed in children immunized by the AKdeltaC-AKdeltaC-KB scheme; no significant difference was found in the content of the protective titres of diphtheria and tetanus antitoxins. The duration of preservation of postvaccinal antibodies against all the AKdeltaC-vaccine components and increase in their amount after the first revaccination (in 1.5-2 years) was the same in both the groups of children. A greater epidemiological efficacy of pertussis antigen was revealed by prolonged observation in immunization by the AKdeltaC-AKdeltaC-KB sheme in comparison with immunization by the official scheme (pertussis incidence per 100 thousand children proved to be 12.7 and 71.2, respectively).

Data are presented on the study of possibilities of the application of the passive hemagglutination test for titration of the blood sera of mice, guinea pigs and rabbits immunized with Cl. perfringens toxoid. A diagnostic agent obtained by the sensitization of formalin- and tannin-treated sheep erythrocytes with the serologically pure toxoid, and homologous sera (as standard) were used in this test. A high immune response of BALB/c and C3H mice to the Cl. perfringens toxoid permits to suggest inbred mice as a model for the immunological and immunogenetic studies connected with this toxoid.

For the first time O antigens obtained from phagolysates were proved to be suitable for use as material for the production of highly specific erythrocyte diagnostic preparations. O antigens obtained from Salmonella by two methods, i.e. phage disintegration and Grasset's method, were subjected to comparative chemical analysis and found to have no essential difference. Nevertheless, the sensitizing potency of O antigens obtained from phagolysates were experimentally shown to be 3 times greater than that of O antigens obtained by Grasset's method. The optimum sensitizing doses established in the passive hemagglutination test for O antigens obtained by both methods indicated that these antigens were highly sensitive and specific.

The work deals with the study of the possibility of using the passive hemagglutination inhibition test (antibody neutralization) for the determination of the antigenic activity of botulinum toxoids, types A, B and E. Erythrocytic diagnostic preparations were shown to allow the determination of up to 0.1 g of antigen. At the same time in vitro determinations were found to satisfactorily correlate with the results of in vivo determinations of the antigenic activity of these toxoids in the antitoxin-fixation test.

The comparative study of 5 analogs of muramyldipeptide (MDP) on primary and secondary immune response to bovine serum albumin has been studied. The adjuvant activity of the MDP analogs has been shown to be closely connected with their structure. Thus, the replacement of glutamine by aspartic acid leads to the loss of adjuvant properties, and the replacement of L-alanine by its stereoisomer causes a perceptible decrease in these properties. The most active analog of MDP is GlcNAc-MurNAc-Ala-D-Glu-NH2 which produces a stimulating effect when introduced parenterally (subcutaneously and intraperitoneally) in a dose of 1 microgram, and orally in a dose of 100 micrograms.

When comparing delayed hypersensitivity (DN) to B. pertussis corpuscular antigens with the agglutinogenic composition of B. pertussis, as well as to its histamine-sensitizing, leukocyte-sensitizing, adjuvant and hemagglutinating activity, no correlation was detected between the specific sensitizing properties of these antigens and the serotype and studied nonspecific properties of B. pertussis. The DH level correlated with the protective activity of B. pertussis corpuscular antigens and the ultrasonic fractions of B. pertussis. The close correlation of these two phenomena suggest that DH-inducing and protective B. pertussis antigens are identical, though their action has different manifestations, depending on the method of administration of the antigen preparation. On these grounds a new method for evaluating the immunogenicity of B. pertussis antigens is proposed. This method consists in comparing the sensitizing activity of the antigen under test and that of the national standard.

Mice belonging to a number of inbred strains were immunized intradermally with Cl. oedematiens alpha-toxoid. The immunization was repeated 30 days later. On the 20th and the 30th days after the first injection and on the 10th day after the second one the antibody level against the toxoid was determined in the blood of mice by the passive hemagglutination test. The maximum response to the primary immunization was observed in the mice of the C3H strain, and the minimum one--in mice of the DBA/2 strain; the difference was more than 30-fold. The rest of the strains used in the test (A,CBA, BALB/c, AKR, CC57BR) displayed an intermediate level of the immune response. The differences reduced after the repeated immunization. The immune response to this antigen in mice is supposed to be genetically controlled.

The study revealed that the immunization of children with adsorbed DPT vaccine from the age of 3-4 months, as compared with the immunization of children from the age of 5-6 months, did not lead to an essential increase in the coverage of children with immunization at the period under study (1970-1983) and did not affect the total level of pertussis morbidity, as well as the proportion of children aged up to 1 year in the total number of pertussis cases. Children immunized at an early age produced antibodies in titers, equivalent to the titers in older children, but their immunity against pertussis, in contrast to their immunity against diphtheria and tetanus, was retained for a shorter period. The injection of adsorbed DPT vaccine at the age of 3-4 months was accompanied by a poorly pronounced increase in the content of IgG, the predominant synthesis of IgM and the suppression of the synthesis of IgA. The shift of the start of vaccination to the age of 3-4 months has probably some immunological grounds for diphtheria and tetanus, but it is premature with respect to pertussis.

The influence of homosensitization with syngeneic tissue antigens on immune response to adsorbed DPT vaccine and sheep red blood cells (SRBC) was studied in experiments in CBA mice and noninbred white mice. These experiments revealed that preliminary homosensitization suppressed the production of antibodies to the components of adsorbed DPT vaccine, while after immunization with SRBC the immunosuppressing effect of homosensitization was absent.

The authors studied the antigenic activity of Bordetella pertussis during stab cultivation. For the first time there were revealed changes (oscillations) of antigenic activity: formation of 3 peaks of which the middle was the highest. A possibility of improving the quality of pertussis vaccine by using biomass at the height of the peak was experimentally founded.

An experiment on guinea pigs immunized with staphylococcal vaccine prepared from water-soluble antigens revealed that the degree of developing sensitization and specific resistance was essentially determined by the method and schedule of the administration of the preparation. The intranasal administration of the vaccine induced a lesser degree of sensitization in comparison with its subcutaneous injection. The optimum response to the administration of the vaccine (a low sensitization level and a high degree of protection from infection) was observed in the animals immunized first intranasally and then by subcutaneous injection. The subcutaneous injection of the preparation in combination with its subsequent intranasal application induced a more pronounced degree of sensitization and a lesser degree of protection from infection.

Human IgG, IgM and IgA produce a pronounced protective effect, preventing enterobacteria from penetration into the mucous membrane of the proximal section of the small intestine of mice in antibiotic-induced dysbacteriosis. Normal mouse IgG and IgM, in contrast to IgA, are effective against mucosal enterobacteria of the small intestine. Immune mouse IgG, IgM and IgA show greater activity in protecting the mucous membrane than normal immunoglobulins of these classes.