Article

Quantitative estimation of diphtheria and tetanus toxoids. 4. Toxoids as international reference materials defining Lf-units for diphtheria and tetanus toxoids.

WHO International Laboratory for Biological Standards, State Serum Institute, Copenhagen S, Denmark.
Biologicals (Impact Factor: 1.62). 02/1990; 18(1):11-7. DOI: 10.1016/1045-1056(90)90063-6
Source: PubMed

ABSTRACT The Lf-unit, which is used in the control of diphtheria and tetanus toxoid production and in some countries also to follow immunization of horses for production of antitoxins, has hitherto been defined by means of antitoxin preparations. A diphtheria toxoid and a tetanus toxoid preparation, both freeze-dried, were examined in an international collaborative study for their suitability to serve as reference reagents in the flocculation tests and for defining the Lf-units. It was shown that flocculation tests using the reference toxoids are very reproducible and reliable and the WHO Expert Committee on Biological Standardization established: the toxoid called DIFT as the International Reference Reagent of Diphtheria Toxoid for Flocculation Test with a defined content of 900 Lf-units of diphtheria toxoid per ampoule; and the toxoid called TEFT as the International Reference Reagent of Tetanus Toxoid for Flocculation Test with a defined content of 1000 Lf-units of diphtheria toxoid per ampoule.

0 Bookmarks
 · 
122 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Diphtheria toxoid, which is an important vaccine in the expanded program of immunization (EPI) in the developing countries, was microencapsulated using poly(D,L,-lactide) of 49,000 molecular weight and the in-water drying technique. The microcapsules were subjected to an in vitro antigen release study using a sensitive enzyme-linked immunosorbent assay (ELISA) developed in the laboratory. Antibody titers in immunized Balb/C mice were also determined using direct ELISA. The antibody units in the immunized group till day 75 were quite comparable to those in the group receiving conventional three-dose injection of diphtheria toxoid with calcium phosphate as an adjuvant. SEM photographs of the microcapsules during in vitro degradation demonstrated the erosion kinetics of the polymer, leading to controlled release of the antigen.
    Pharmaceutical Research 08/1991; 8(7):958-61. · 4.74 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tetanus toxoid is a vital primary reference material used for standardization of assays required to establish the antigenic purity of tetanus toxoid for vaccine production. Several formulations were assessed and ampouled fills of each formulation lyophilised. The relative Lf content determined by Ramon flocculation, SRD, and ELISA assays was measured. The stability of the tetanus toxoid activity in each formulation was assessed by accelerated degradation studies. Formulations containing glycine were not suitable in flocculation tests but both sorbitol and trehalose formulations were. The trehalose/sodium chloride formulation had a good appearance, showed good activity in all assays and maintained its activity best under stress conditions. This formulation has been applied to a large scale batch of ampoules prepared as a WHO candidate replacement standard, evaluated in a collaborative study and accepted as a replacement WHO IS for use in flocculation test (WHO ECBS, October 2007, ref no BS/07.2061). The stability of this formulation was also excellent for the large scale batch. The benefits of using thermal analysis and freeze drying microscopy coupled with small scale lyophilisation trials in order to screen formulations for the preparation of batches of biological reference materials are demonstrated.
    Biologicals 10/2008; 37(1):1-7. · 1.62 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Phage display technology is a powerful in vitro method for the identification of specific monoclonal antibodies (antibody fragments) to an antigenic target and allows the rapid generation and selection of high affinity, fully human antibodies directed toward any disease target appropriate for antibody therapy. In the present study, we exploited the phage display technology for the selection of an antigen binding fragment (Fabs) toward tetanus toxoid using human naïve phage antibody library constructed from peripheral blood lymphocytes of naïve human donors. The phages displaying Fab were subjected to three rounds of bio-panning with tetanus toxoid as antigen on a solid phase. The high affinity antibody fragments were expressed in HB2151 strain of Escherichia coli and purified by immobilized metal affinity chromatography. The binding activity and specificity of the antibody fragment was established by its reactivity toward tetanus toxoid and non-reactivity toward other related toxins as determined by enzyme-linked immunosorbent assay and immunoblot analysis. The selected Fab fragment forming the antigen-binding complexes with the toxoid in flocculation assay indicates that the Fab may have a potential neutralizing ability toward antigen.
    European journal of microbiology & immunology. 03/2014; 4(1):45-55.

Full-text (2 Sources)

View
11 Downloads
Available from