Characteristics of the antitoxic and antibacterial immune response in children with diphtheria

As found in this study, the development of the manifest forms of diphtheria occurred in the presence of lower levels of antitoxic antibodies, than bacterial carrier state. The level of antitoxic antibodies in all patients, irrespective of the time of their examination, was higher than that of antibacterial antibodies. In the dynamics of the disease a considerable increase in antitoxic and antibacterial antibodies was observed in localized and disseminated forms of diphtheria and, to a considerably lesser degree, in toxic and subtoxic forms of diphtheria, while not observed in the process of the formation of bacterial carrier state. The dynamics of a rise in the levels of antitoxic and antibacterial antibodies in the manifest forms of diphtheria infection made it possible to differentiate between the cases of toxigenic Corynebacterium diphtheriae carrier state and those of the disease.     

Characteristics of antitoxic and antibacterial immune response in nontoxic forms of oropharyngeal diphtheria

The enzyme immunoassay system (EIA) for differentiation of antibodies in therapeutic heterogeneous antitoxic serum and antibodies to Corynebacterium diphtheriae toxigenic strains in patients and carriers was developed. The use of EIA permitted the dynamic evaluation of the characteristics of humoral antitoxic and antibacterial immune response in 50 patients with the localized and disseminated forms of stomatopharyngeal diphtheria and 14 "healthy" carriers of toxigenic C. diphtheriae. As revealed in this study, the symptoms of the disease in patients with disseminated forms of stomatopharyngeal diphtheria developed in the presence of statistically significant low quantitative values of antitoxic and antibacterial antibodies to C. diphtheriae antigens. In the group of patients with the localized forms of the disease the initially low level of antitoxic antibodies was detected with the concentration of antibacterial antibodies remaining unchanged. During the period of convalescence the levels of antitoxic antibodies in both groups reached those of healthy persons. In case of localized forms of the disease the level of antibacterial antibodies decreased as compared with healthy persons, starting from the second week of the disease. The period of convalescence in the disseminated forms was characterized by the low concentration of antibacterial antibodies. Carrier state was formed in the presence of high levels of antitoxic antibodies and significantly low levels of antibacterial ones.     

Mathematical model of the infection process in diphtheria for determining the therapeutic dose of antitoxic anti-diphtheria serum

It is known that administration of horse serum against diphtheria toxin can cause autoimmune and allergic complications. Therefore it is important for improvement of serotherapy to develop methods of prediction of disease course and quantity of diphtheria toxin and antitoxic antibodies in a serum. We have developed the mathematical model of diphtheria infection, which consists of six differential equations describing dynamics of diphtheria toxin and antitoxic antibodies in a serum, quantity of infection agent and macrophages in a site of inflammation. This mathematical model allows to predict the course of infectious process, the level of diphtheria toxin and antitoxic antibodies in the sera of people with diphtheria and to calculate the individual therapeutic dose of antitoxic serum for each patient.     

The humoral immunity against diphtheria

Results of the conducted study showed that naturally acquired antibacterial and postvaccinal antitoxic antibodies against diphtheria were found in human blood sera. Challenge of ADT-M toxoid to adults resulted in production of antitoxic as well as antibacterial antibodies in high concentrations. In response to challenge of ADT-M toxoid simultaneously with bacterial vaccine against diphtheria Codivac both antibacterial and antitoxic antibodies were synthesized in blood on optimal physiologic levels. This study revealed dynamics of some specific characteristics of humoral immune response after challenge of two different vaccines against diphtheria--ADT-M toxoid and Codivac vaccine.     

Immunological surveys of antibodies against B. pertussis and B. parapertussis in some African and Asian countries.

Immunological surveys in African and Asian countries showed a different degree of herd immunity in the respective countries and the circulation of various types of B. pertussis. Antibodies against B. parapertussis, the second aertiological agent of whooping cough, were found in all countries in all age groups. Before planning any vaccination program, attention should be paid to the vaccine concerning the content of all types of B. pertussis, as was shown in the results of the testing of different vaccines used in Mongolia and Algeria. It is also possible to estimate the age limit for vaccination and thus economic use of the vaccine. The contemporary state of reporting whooping cough cases is very unsatisfactory.     

Evaluation of the immunological effectiveness of the planned vaccinal prophylaxis of diphtheria and tetanus in Sverdlovsk and Sverdlovsk Province

The level and intensity of antitoxic immunity to diphtheria and tetanus in children and adolescents were determined. The presence of tetanus antitoxin in titers exceeding the protective level in 96.3-98.5% of the examined children and adolescents is indicative of a high actual coverage by immunization. Protective titers against diphtheria were lower. There was no essential difference in the levels of protection in children immunized according to the vaccination schedule and in those immunized with some deviations from this schedule. A considerable part of newborns and children aged 3 months had antibodies to diphtheria and tetanus antitoxins. After the third booster immunization changes in antidiphtheria immunity characteristics occurred only in 2.5% of the vaccines and no changes in antitetanus immunity characteristics were observed.     

Antidiphtheria immunity in children after immunization with adsorbed DPT vaccine and ADPT-M toxoid

Antidiphtheria immunity in children aged 3-15 years was evaluated, depending on their age, the vaccinal preparation chosen for immunization and the immunization schedule. Adsorbed DPT vaccine was shown to have a higher immunological activity in comparison with adsorbed DT toxoid with reduced antigen content. The relationship between the tension of antidiphtheria antitoxic immunity in children and the possibility of the formation of the clinical forms of diphtheria with different severity in the patients was established. Children aged 4-6 years were considered to be a group of high risk in diphtheria morbidity, as it was among the children of this group that toxic and subtoxic forms of diphtheria were most often registered (44.9 +/- 7.1% of the examinees); in addition, a high proportion of children seronegative to this infection (26,3 +/- 2.2%) was observed in this group.     

Specific prevention of diphtheria in adults in foci of this infection

The studies demonstrated the immunological and epidemiological effectiveness of a single injection of adsorbed diphtheria-tetanus toxoid with reduced antigen content for adults: intense antidiphtheria immunity in 92.3% of the vaccinees 1-3 months and in 94.5% of the vaccinees 1 year after the injection. This immunity remained sufficiently intense for 3 years (the term of observation). The geometric mean of antitoxic titers was 0.84 I. U./ml. The highest intensity of immunity appearing after the injection was observed in persons aged 18-20 years who showed the highest antitoxic titers (exceeding 0.5 I. U./ml) in 100% of cases, the lowest intensity was registered in the age group of 30-39 years; in 14.2% of these vaccinees antitoxic titers were below the protective level. In other age groups (40-49 years, 50 years and over) the intensity of immunity was high. The geometric mean of the titers of diphtheria antitoxin were 1.2 I. U./ml and 2.1 I. U./ml respectively. In none of the foci under study the spread of the manifest forms of the disease was observed.     

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.     

Specific antibodies and their role in the formation of antidiphtheria immunity

In human sera, studied with the use of the enzyme immunoassay, antidiphtheria postvaccinal antitoxic IgG and naturally acquired antibacterial IgG, IgM and IgA were detected. In the blood of children and adults aged up to 50 years antitoxic IgG were present at normal and high concentrations. In 50% of children antibacterial IgA were absent, while specific antibacterial IgM could be found at high concentrations. Changes in the content of antibacterial antibodies of different classes in sera were observed with age. More than 90% of adults had antibacterial IgA and IgG at normal and hig concentrations, while the level of IgM decreased. Under the influence of ecological, social, anthropogenic and other environmental factors the optimum levels of specific antibodies were replaced by anomalous ones, which led to an increased number of persons susceptible to diphtheria infection and in the intensity of the circulation of the infective agent. The deficiency of antidiphtheria antibacterial antibodies in the blood determined the necessity of correcting immunity by means of not only toxoid, but also bacterial antigens.     

Blood antigens in the AB0 system and susceptibility of humans to diphtheria

The analysis of a large number of diphtheria cases (1326) at the peak of diphtheria morbidity in Russia (1993-1994) revealed that the intensity of antidiphtheria antitoxic immunity was age-dependent with a sharp immunodeficiency in the population aged 35 years and older. As adaptive capacity of the organism decreases, the positive associative links between immunity to diphtheria and the AB0 blood groups become evident. Populations with phenotype B (III) had the largest diphtheria immune stratum at the age of 35 years and over as compared to 3 other phenotypes. The genotypic analysis of serological data may be of practical importance for the detection of the degree of predisposition of humans to infectious diseases.     

Immunological structure of the population in a system of epidemiological surveillance of diphtheria

The characteristics of antitetanus and antidiphtheria immunity in children, adolescents and adults in Perm have been determined by means of the passive hemagglutination test, and the tendency towards the decrease of their immunity to diphtheria with the increase of their age has been established. The registered and actual coverage of children and adolescents by immunization is characterized on the basis of the presence of antibodies to the tetanus component of combined vaccines. A considerable proportion of persons at boarding schools and vocational technical schools has been found to be seronegative with respect to diphtheria. The seasonal dynamics of antitoxic immunity is presented.     

Recombinant fluorescent models for studying the diphtheria toxin

Diphtheria toxin is a major factor of the pathogenicity of the causative agent of diphtheria Corynebacterium. Due to a small size, it is of considerable interest as the basis for the development of synthetic protein molecules with a transport function, e.g., immunotoxins. In this work we describe the expression and characterized nontoxic recombinant fluorescent derivatives of the diphtheria toxin and its nontoxic CRM197 mutant. The proteins obtained can be used for studying receptor-binding and transport functions of the toxin in cells, evaluation of the expression level of the toxin proHB-EGF receptor membranes, immunization and generation of specific antibodies against the toxin, as well as for the development of diagnostic test-systems for the diphtheria toxin and antitoxic antibodies.     

Long-Term Protection against Diphtheria in the Netherlands after 50 Years of Vaccination: Results from a Seroepidemiological Study

Background and Aims

To evaluate the National Immunisation Programme (NIP) a population-based cross-sectional seroepidemiological study was performed in the Netherlands. We assessed diphtheria antitoxin levels in the general Dutch population and in low vaccination coverage (LVC) areas where a relatively high proportion of orthodox Protestants live who decline vaccination based on religious grounds. Results were compared with a nationwide seroepidemiological study performed 11 years earlier.

Methods

In 2006/2007 a national serum bank was established. Blood samples were tested for diphtheria antitoxin IgG concentrations using a multiplex immunoassay for 6383 participants from the national sample (NS) and 1518 participants from LVC municipalities. A cut-off above 0.01 international units per ml (IU/ml) was used as minimum protective level.

Results

In the NS 91% of the population had antibody levels above 0.01 IU/ml compared to 88% in the 1995/1996 serosurvey (p<0.05). On average, 82% (vs. 78% in the 1995/1996 serosurvey, p<0.05) of individuals from the NS born before introduction of diphtheria vaccination in the NIP and 46% (vs. 37% in the 1995/1996 serosurvey, p = 0.11) of orthodox Protestants living in LVC areas had antibody levels above 0.01 IU/ml. Linear regression analysis among fully immunized individuals (six vaccinations) without evidence of revaccination indicated a continuous decline in antibodies in both serosurveys, but geometric mean antibodies remained well above 0.01 IU/ml in all age groups.

Conclusions

The NIP provides long-term protection against diphtheria, although antibody levels decline after vaccination. As a result of natural waning immunity, a substantial proportion of individuals born before introduction of diphtheria vaccination in the NIP lack adequate levels of diphtheria antibodies. Susceptibility due to lack of vaccination is highest among strictly orthodox Protestants. The potential risk of spread of diphtheria within the geographically clustered orthodox Protestant community after introduction in the Netherlands has not disappeared, despite national long-term high vaccination coverage.     

Booster vaccination against tetanus and diphtheria: insufficient protection against diphtheria in young and elderly adults

We have recently demonstrated that single shot vaccinations against tetanus and diphtheria do not lead to long-lasting immunity against diphtheria in elderly persons despite administration at 5 year intervals. In the present study we have immunized a group of young adults against tetanus and diphtheria to compare the pre- and 28 days post-vaccination immune responses in the young group with results of the same vaccination performed in an elderly group of a previous study. We also studied protection in both groups 5 years after vaccination. We compared antibody titers at all three time points and also analyzed the T cell responses in both age groups 5 years after vaccination.Before vaccination 9 % of the elderly persons were not protected against tetanus, and 48 % did not have protection against diphtheria. In the young group all participants were protected against tetanus, but 52 % were also unprotected against diphtheria before vaccination. 28 days after vaccination 100 % of all participants had protective antibody concentrations against tetanus and only a small percentage in each age group (<10 %) was unprotected against diphtheria. 5 years later, 100 % of both cohorts were still protected against tetanus, but 24 % of the young and 54 % of the elderly group were unprotected against diphtheria. Antibody concentrations against diphtheria measured by ELISA correlated well with their neutralizing capacity. T cell responses to tetanus and diphtheria did not differ between young and old persons. We conclude that booster vaccinations against tetanus and diphtheria according to present recommendations provide long-lasting protection only against tetanus, but not against diphtheria, independently of age. In elderly persons, the level of protection is even lower, probably due to intrinsic age-related changes within the immune system and/or insufficient vaccination earlier in life.     

Surveillance of pertussis in the CSSR. IV. Immunological surveys of antibodies to pertussis and parapertussis in the Bohemian regions and in Slovakia in 1958 - 1971.

A comparison of the results of repeated immunological surveys with the notification of morbidity and mortality to pertussis and parapertussis revealed direct dependence and simultaneously confirmed the effectiveness of Czechoslovak vaccine. Immunological surveys should be continued in spite of the fact that morbidity of pertussis is low at present, because immunological surveys may lead to timely detection of shortcomings in the quality of vaccination and vaccine. The results after 14 years of systematic vaccination and revaccination and consequent follow-up to the state of immunity in the population and of other factors in the pertussis surveillance programme rank among the other achievements of epidemiology and hygiene in Czechoslovak health services. Contemporary immunological surveys show that the state of immunity in Czechoslovak child population is such as to exclude the occurrence of pertussis in epidemics in the nearest future. The situation is different in parapertussis where epidemic incidence is still possible and where epidemics regularly occur in children of prae-school age.     

The coagglutination reaction for detecting diphtheria toxin

High-titer antidiphtheria antitoxic rabbit serum has been obtained, and on the basis of this serum a coagglutinating diagnosticum has been developed. The sensitivity of the test has been found to depend on the content of antitoxic antibodies in the serum and on its purity. Diagnostica prepared from native serum containing 500 I. U./ml (a titer of 1:51, 200 in the passive hemagglutination test) permit the detection of 0.02-0.03 Lf/ml of diphtheria toxin. A decrease in antibody titer to 5-25 I. U./ml leads to a drop in sensitivity to 0.2-2 Lf/ml. The use of LgG fraction and pure antibodies increases the sensitivity of the test to 0.002-0.003 Lf/ml. The possibility of detecting toxin in Corynebacterium diphtheriae strains is shown.     

Epidemiology of diphtheria in the RSFSR during mass immunization over many years

The work defines the characteristic epidemiological features of diphtheria in the RSFSR at the present moment when a high level of antitoxic immunity is generally determined in children. With the diphtheria morbidity level having, on the whole, a sporadic character in the RSFSR, the intensification of the epidemic process has been found to occur in some regions. Changes in the ratio of morbidity rates among the urban and rural population are observed, the morbidity rate among the latter have the tendency towards increase. At present the characteristic feature of diphtheria is the prevalence of adults in the general morbidity structure. An important fact is a permanently high level of toxigenicity in Corynebacterium diphtheriae. As before, autumn is the season of the highest morbidity level.     

Incidence of Rubella Antibodies in Female Subjects

Sera from females aged 1 to 40 years were assayed for rubella virus antibodies. Results showed that by age 14 years, 60% had antibodies and that by 19 years, 70% were positive. This figure rose to 80% by 24 years of age and remained unchanged in older age groups.A comparison of the incidence of high and low levels of antibodies in each age group revealed that antibody levels fell between ages 20 and 40 years. Only 20% of individuals in the latter group had a high antibody level compared to 80% in the former.These results are discussed as they relate to the problems of reinfection and possible vaccination procedures.     

Antibody status to poliomyelitis,measles, rubella,diphtheria and tetanus,Ontario, 1969-70: deficiencies discovered and remedies required.

A serologic survey was made in 15 health unit areas, testing some 5000 individuals in the age groups 4 to 6, 11 to 13, 15 to 17 and 23 to 45 years. Two types of serious deficiency were found. Only 65% of children 4 to 6 years old had antibodies to all three types of poliovirus, the antibodies being due almost entirely to immunization with Salk vaccine. Even in children who had had six or more doses only 74% had antibodies to the three types. The high percentage of students 11 to 13 and 15 to 17 years old with poliovirus antibodies can be attributed largely to natural infection and to Sabin vaccine in the mass campaign of 1962, as well as to Salk vaccine. In children who had received Sabin vaccine as well as Salk vaccine a very high level of immunity was found. The immunity of the school-age population will decline to an insufficient level unless Sabin vaccine is used after immunization with Salk vaccine. Of children 4 to 6 years old 18% had no diphtheria antitoxin and 6% had no tetanus antitoxin. Even in those who had had six or more doses of the antigens 5% had no diphtheria antitoxin and 1 to 2% had no tetanus antitoxin. This apparently refractory state is probably due to the use of unadsorbed toxoids, and it is clear that adsorbed toxoids should be used. In the adults, diphtheria antitoxin was found in only 55% and tetanus antitoxin in only 38%.