Development of an ELISA for measuring the activity of tetanus toxoid in vaccines and comparison with the toxin neutralization test in mice

Nuclear magnetic resonance immunoassay of tetanus antibodies based on the displacement of magnetic nanoparticles

A nuclear magnetic resonance (NMR) immunoassay based on the application of carbon-coated iron nanoparticles conjugated with recognition molecules was designed. The principle of the assay is that ELISA plates are coated with a capture element, and then an analyte is added and detected by conjugating the magnetic nanoparticles with recognition molecules. Afterwards, the elution solution (0.1-M sodium hydroxide) is added to displace the magnetic nanoparticles from the well surfaces into the solution. The detached magnetic nanoparticles reduce transverse relaxation time (T2) values of protons from the surrounding solution. A portable NMR relaxometer is used to measure the T2. Magnetic nanoparticles conjugated with streptavidin, monoclonal antibodies, and protein G were applied for the detection of biotinylated albumin, prostate-specific antigen, and IgG specific to tetanus toxoid (TT). The limit of detection of anti-TT IgG was 0.08-0.12 mIU/mL. The reproducibility of the assay was within the acceptable range (CV < 7.4%). The key novelty of the immunoassay is that the displacement of the nanoparticles from the solid support by the elution solution allows the advantages of the solid phase assay to be combined with the sensitive detection of the T2 changes in a volume of liquid.

Cross-Reactive Effects of Vaccines: Heterologous Immunity between Tetanus and Chlamydia

Vaccines can have heterologous effects on the immune system, i.e., effects other than triggering an immune response against the disease targeted by the vaccine. We investigated whether monoclonal antibodies (mAbs) specific for tetanus could cross-react with Chlamydia and confer heterologous protection against chlamydial infection. The capability of two tetanus-specific mAbs, namely mAb26 and mAb51, to prevent chlamydial infection has been assessed: (i) in vitro, by performing a neutralization assay using human conjunctival epithelial (HCjE) cells infected with Chlamydia trachomatis serovar B, and (ii) in vivo, by using a guinea pig model of Chlamydiacaviae-induced inclusion conjunctivitis. The mAb26 has been superior in comparison with mAb51 in the prevention of chlamydial infection in HCjE cells. The mAb26 has conferred ≈40% inhibition of the infection, compared to less than 5% inhibition in the presence of the mAb51. In vivo, mAb26 significantly diminished ocular pathology intensity in guinea pigs infected with C. caviae compared to either the mAb51-treated or sham-treated guinea pigs. Our data provide insights that tetanus immunization generates antibodies which induce heterologous chlamydial immunity and promote protection beyond the intended target pathogen.

Neisseria meningitidis native outer membrane vesicles containing different lipopolysaccharide glycoforms as adjuvants for meningococcal and nonmeningococcal antigens

We evaluated the adjuvant effect of a modified glycoform of lipopolysaccharide (LPS) (LgtB-LpxL1) compared to that of the nonmodified glycoform Lpxl1 serogroup B meningococcal H44/76 native outer membrane vesicles (nOMVs) on immune responses to vaccination with the recombinant meningococcal protein, rPorA, tetanus toxoid, or meningococcal serogroup C capsular polysaccharide. We used LgtB-LpxL1 LPS because the disruption of the lgtB gene, which results in the exposure of N-acetylglucosamine-galactose-glucose residues in the LPS outer core, has been shown to enhance the activation of human dendritic cells in vitro. The responses were compared to those of a monophosphoryl lipid A (MPL)-based adjuvant and to an aluminum hydroxide suspension. The nOMVs induced blood serum IgG responses against each of the three antigens comparable to those obtained with MPL or aluminum salt. However, nOMVs elicited (i) a lower IgG1/IgG2a ratio against rPorA and (ii) serum bactericidal antibody titers superior to those achieved with aluminum salt, reaching similar titers to those obtained with MPL. Similarly, bactericidal antibody titers induced by immunization with meningococcal serogroup C polysaccharide and nOMVs were similar to those obtained using MPL but were better than those with aluminum salt. Immunization with tetanus toxoid and nOMVs resulted in tetanus toxoid-specific IgG responses similar to those obtained when adjuvanted with aluminum salt. These results highlight the potential utility of meningococcal LpxL1 LPS-containing nOMVs as an adjuvant for recombinant meningococcal protein vaccines and suggest their possible use with a variety of other antigens.

Safety and immunogenicity of a primary course and booster dose of a combined diphtheria, tetanus, acellular pertussis, hepatitis B and inactivated poliovirus vaccine

Primary immunization at 3, 4.5, and 6 months and boosting between 15 and 27 months of age with combined diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus (DTPa-HBV-IPV) vaccine was compared with separate administration of DTPa-HBV and IPV to healthy children (trials DTPa-HBV-IPV-019/033). Antibody titres were measured before and 1 month after primary and booster courses. Solicited local and general symptoms were recorded using diary cards. One month after primary vaccination, all children in both groups developed antibody titres above the assay cut-off for all vaccine components. Significantly higher anti-diphtheria, anti-pertactin (PRN) and anti-polio GMTs were measured following DTPa-HBV-IPV than DTPa-HBV plus IPV. Prior to boosting similar seroprotection/seropositivity rates were recorded in both groups. After boosting all children had seroprotective levels of diphtheria, tetanus, polio and HBV. Criteria for pertussis vaccine response were fulfilled in most children. Significantly higher anti-PRN GMTs were measured following DTPa-HBV-IPV than DTPa-HBV plus IPV. There was no difference between groups in the incidence or intensity of local and general symptoms after primary or booster vaccination, except for fever which was more frequent after the booster dose in the combined vaccine group. Both vaccine regimens were well tolerated and immunogenic, however the combined administration has the advantage of being administered as a single injection.

The monoclonal antibody 26 raised against tetanus toxoid also recognizes tetanus toxin and β2-glycoprotein I - its binding properties in vitro and potential applications

A murine monoclonal IgG1 antibody, marked as MAb26, specific for tetanus toxoid has been immunochemically characterized. By performing enzyme-linked immunosorbent assays (ELISAs) and western blot analyses, it was demonstrated that MAb26 reacted with tetanus toxoid, tetanus toxin and ?2-glycoprotein I (?2GPI). According to the results, MAb26 recognized the sequential epitope on the tetanus heavy chain. The affinity constant, calculated from Scatchard plots of MAb26 binding to tetanus toxoid, was 1.145?108 M-1 and the measurement of the relative affinity of MAb26 by ELISA using thiocyanate elution showed a significantly higher affinity of MAb26 to the toxoid (p = 0.0012) in comparison to the toxin. Additionally, the reactivity of MAb26 toward the toxoid forms increased when the tetanus toxin was detoxified using 8 mM and higher formaldehyde concentrations. The similarity of the tetanus toxoid to several sera proteins, either at the level of its conformation (IL-1?) or at the level of peptide sequences (?2GPI, laminin) favors its role in autoimmunity by the mechanism of molecular mimicry. As the induction of an autoimmune disease is dependent on the breakdown of tolerance, which could be the result of an overt hyperstimulation, the control of the presence and concentration of self-reactive epitopes in vaccine preparations is a prerequisite. In this study, it was shown that MAb26 can: 1) discriminate between the tetanus toxin and different toxoid forms, which makes it a good candidate for antibody control during vaccine preparation; 2) due to its cross-reactivity with ?2GPI, it could provide information on the presence of a potentially dangerous sequential epitope expressed at the protein surface.

Vaccination response to tetanus toxoid and 23-valent pneumococcal vaccines following administration of a single dose of abatacept: a randomized, open-label, parallel group study in healthy subjects

The effect of abatacept, a selective T-cell co-stimulation modulator, on vaccination has not been previously investigated. In this open-label, single-dose, randomized, parallel-group, controlled study, the effect of a single 750 mg infusion of abatacept on the antibody response to the intramuscular tetanus toxoid vaccine (primarily a memory response to a T-cell-dependent peptide antigen) and the intramuscular 23-valent pneumococcal vaccine (a less T-cell-dependent response to a polysaccharide antigen) was measured in 80 normal healthy volunteers. Subjects were uniformly randomized to receive one of four treatments: Group A (control group), subjects received vaccines on day 1 only; Group B, subjects received vaccines 2 weeks before abatacept; Group C, subjects received vaccines 2 weeks after abatacept; and Group D, subjects received vaccines 8 weeks after abatacept. Anti-tetanus and anti-pneumococcal (Danish serotypes 2, 6B, 8, 9V, 14, 19F and 23F) antibody titers were measured 14 and 28 days after vaccination. While there were no statistically significant differences between the dosing groups, geometric mean titers following tetanus or pneumococcal vaccination were generally lower in subjects who were vaccinated 2 weeks after receiving abatacept, compared with control subjects. A positive response (defined as a twofold increase in antibody titer from baseline) to tetanus vaccination at 28 days was seen, however, in ≥ 60% of subjects across all treatment groups versus 75% of control subjects. Similarly, over 70% of abatacept-treated subjects versus all control subjects (100%) responded to at least three pneumococcal serotypes, and approximately 25–30% of abatacept-treated subjects versus 45% of control subjects responded to at least six serotypes.

Immunogenicity and Reactogenicity following Primary Immunisation with a Combined DTaP-HBV Vaccine and a??Haemophilus influenzae Type B Vaccine Administered by Separate or Mixed Injection

OBJECTIVES

The aim of this open, randomised, multicentre trial was to evaluate the immunogenicity and reactogenicity of the tetravalent diphtheria-tetanus-acellular pertussis-hepatitis B (DTaP-HBV) vaccine when given either as a mixed or as a separate concomitant injection with the Haemophilus influenzae type b (Hib) vaccine at 3, 5 and 11 months of age.

METHODS

Antibody against diphtheria, tetanus, pertussis (ELISA), hepatitis B (radioimmunoassay) and Hib polyribosylribitol phosphate (PRP) [radiolabeled antigen binding assay] was determined. Solicited local and systemic adverse events were evaluated on the day of each vaccination and for three subsequent days. Follow-up of unsolicited and serious adverse events was conducted for 30 days following each vaccination.

RESULTS

A total of 360 subjects were enrolled in the study. After completion of the three-dose vaccination course, seroprotective antibody concentrations against diphtheria, tetanus and hepatitis B, together with a pertussis vaccine response, were seen in almost all subjects with immunogenicity results (n = 336). All subjects had post-vaccination Hib anti-PRP antibody concentrations of at least 0.15 mug/mL, and 97.0% and 99.4%, respectively, of the subjects receiving a single or separate injections had Hib anti-PRP antibody concentrations >/=1.0 mug/mL. Addition of the Hib vaccine to the tetravalent DTaP-HBV vaccine did not increase the incidence of local or systemic reactions.

CONCLUSIONS

Combination of DTaP-HBV and Hib vaccines in a single injection is safe, immunogenic and well tolerated, and thus has the potential to simplify the childhood immunisation schedule in Italy.

Development of Sandwich Enzyme‐Linked Immunosorbent Assay for Determination of Tetanus Toxoid Concentration

According to the recommendation of the World Health Organization (WHO), the use of an in vivo test for measuring of the potency of tetanus toxoid vaccine (TTdV) is still unavoidable, but the establishment of a convenient in vitro test would significantly improve the work in this field. A sandwich enzyme-linked immunosorbent assay (sELISA) was developed for a rapid and sensitive quantification of tetanus toxoid (TTd). We produced four monoclonal antibodies (MAbs) designated 41, 51, 62, and 71 that reacted with TTd and recognized different antigenic determinants on TTd. We also used two of these antibodies for developing a sELISA, with MoAb 71 as an immobilized and MoAb 51 as a capture antibody. The measurement range of this assay was from 31-1000 ng/mL and the minimum detection limit for TTd was 31 ng/mL. This high sensitivity of this sELISA and its good reproducibility suggest that the developed method could be reliably used to estimate the concentration of TTd, which could be easily extrapolated to the estimation of vaccine potency.

Tetanus immunization in pregnant women. Serum levels of antitetanus antibodies at time of delivery

The objective of this study was to determine the tetanus immunity status of pregnant women at the time of delivery according to tetanus toxoid (TT) vaccination coverage during their most pregnancy. The serum anti-tetanus antibody levels of 493 mothers who had live births at a hospital in Ankara were determined by enzyme-linked immunosorbent assay (ELISA). Protected women were defined as those with serum antibody levels > or = 0.6 IU/ml. Overall, 69.0% of mothers had protective tetanus antibody titers at the time of delivery. The rates of protection for mothers who had received no vaccination, one TT dose, or two TT doses during pregnancy were 46.4, 93.5, and 95.6%, respectively. Vaccinating every pregnant woman with at least one dose of TT would be an affordable and effective way to protect against neonatal tetanus, and would be a step toward eliminating the deaths that continue to occur due to this preventable disease in Turkey.

Calibration of replacement international standard and European pharmacopoeia biological reference preparation for tetanus toxoid, adsorbed

Here we report the characterisation of a preparation of tetanus toxoid, adsorbed, and its calibration by 27 laboratories in 19 countries in a joint international collaborative study co-sponsored by World Health Organization (WHO) Expert Committee of Biological Standardization (ECBS) and the European Biological Standardisation Programme of European Directorate for the Quality of Medicines (EDQM), Council of Europe. Calibration was in terms of the Second International Standard (I.S.) for Tetanus Toxoid, Adsorbed, by the established WHO/European Pharmacopoeia (Ph Eur) challenge methods. The replacement standard preparation was found to have a unitage of 469 IU/ampoule on the basis of its calibration in guinea-pigs and 496 IU/ampoule on the basis of its calibration in mice. Assessment, both within the collaborative study and as part of candidate characterisation, indicated satisfactory stability of the candidate preparation. This study also provided some information on the effect of mouse strain on potency testing of tetanus vaccines. A limited assessment of the impact of the replacement standard on testing of current production batches of vaccines was also carried out by four manufacturers. This study did not directly address the serological approaches to potency testing. However, one laboratory offered data from mouse serology assay, which gave comparable estimates to in vivo mouse bioassay. Based on the results of this study and with the agreement of participants, the candidate standard was established as the Third International Standard for Tetanus Toxoid, Adsorbed (coded 98/552) by the WHO Expert Committee of Biological Standardization (ECBS) in November 2000. The same preparation was also established as the second Ph Eur Biological Reference Preparation (Ph Eur BRP, batch no. 2) by the Steering Committee of the Biological Standardisation Programme of the EDQM and approved by the European Pharmacopoeia Commission.

Serum antibodies to diphtheria-tetanus-pertussis vaccine components in Argentine children

The Argentine vaccination schedule against diphtheria, tetanus and pertussis (DTP) recommends three doses of DTP vaccine at 2, 4 and 6 months of age, two boosters at 18 months and 6 years, a booster dose of tetanus vaccine every 10 years and two doses during pregnancy. To evaluate the effect of this schedule, antibodies against pertussis toxin (PT) and filamentous hemagglutinin (FHA) and against tetanus and diphtheria toxoids were determined by ELISA in serum samples from children (1 month to 6 years) who received different doses of DPT vaccine: 0 dose (n = 50), 1 dose (n = 25), 2 doses (n = 25), 3 doses (n = 55), first and second booster (n = 25); 25 pregnant women and their offspring, and 45 adults. High antibody levels against PT (> 140 EU/ml) and FHA (> 80 EU/ml) were recorded in mothers and in the newborn. Antibody titers against PT increased with the number of doses given and decreased with time. Full protection against tetanus (titers > 0.1 IU/ml) was observed in the group of adults (0.37 IU/ml), in mothers (4.4 IU/ml) and their newborn offspring (5.5 IU/ml), and in children after receiving the second dose of DTP vaccine (1.86 IU/ml). The immune status for diphtheria was far lower, as most of the groups lacked adequate protection. After the third dose of DTP vaccine, only 78% of the children had antibody titers above the protective level (0.1 IU/ml). Since antibody levels considered to provide full protection were only achieved after the first booster dose of DTP vaccine, the primary three-dose schedule seems to be insufficient to confer adequate immunity in all vaccinees. Because of the high proportion of non-protected adults, a booster dose of Td vaccine should be considered for this group.