The Potential of Physicochemical and Immunochemical Assays to Replace Animal Tests in the Quality Control of Toxoid Vaccines

Abstract

This is the 61st report of a series of workshops organised by the European Centre for the Validation of Alternative Methods (ECVAM). The main goal of ECVAM, as defined in 1993 by its Scientific Advisory Committee, is to promote the scientific and regulatory acceptance of alternative methods which have scientific relevance and which reduce, refine or replace the use of laboratory animals. One of the first priorities set by ECVAM was the implementation of procedures that would enable it to become well informed about the stateof-the-art of non-animal test development and validation, and the potential for the possible incorporation of alternative tests into regulatory procedures. It was decided that this would be best achieved by the organisation of ECVAM workshops on specific topics, at which groups of invited experts would review the current status of non animalbased tests and their potential uses, and make recommendations about the best ways forward (1).The workshop on the potential of physicochemical and immunochemical assays to replace animal tests in the quality control of toxoid vaccines was held at ECVAM on 14-15 April 2005, under the cochairmanship of Coenraad Hendriksen and Gideon Kersten. The objectives of the workshop were: a) to review the state-of-the-art of physicochemical, biochemical and immunochemical tests for the quality control of diphtheria and tetanus toxoid vaccines; and b) to identify possibilities for and limitations to their use in the regulatory framework, i.e. for replacing the use of in vivo tests. The outcome of the discussions and the recommendations of the workshop participants are summarised in this report.

Structural correlates of carrier protein recognition in tetanus toxoid-conjugated bacterial polysaccharide vaccines

“…Tetanus toxoid conformation is considered to be a good characteristic of vaccine quality [26], although there is no evidence suggesting that maintenance of native-like conformation is a requirement for its immunogenicity and protection. Intrinsic fluorescence spectroscopy has been used to differentiate between TT conformers through the spectral features of its aromatic amino acid side-chains [14,27–29].…”

Non-animal replacement methods for veterinary vaccine potency testing: state of the science and future directions

“…Currently, in the United States and the EU, the potency tests for human and veterinary vaccines consist of vaccination of guinea pigs and serological evaluation of antitetanus toxoid antibodies by an indirect ELISA [44] or a toxin-binding inhibition (ToBI) test [45,47]. Efforts to develop a replacement test for either human or veterinary tetanus vaccines are impeded by the facts that toxoid vaccines are not well characterized, and potential analytical tests, including physiochemical and immunochemical tests, require much greater data generation, characterization, and validation for in-process and final product characterization [120].…”

“…A proposed blueprint for the development of an in vitro replacement potency test for Clostridium tetani included (1) the validation of currently available physiochemical and immunochemical tests, (2) parallel testing of vaccines by in vitro and serological methods, and (3) regulatory acceptance and implementation [120,121]. A focused, coordinated effort by human and veterinary tetanus vaccine experts to develop a replacement implementation plan was given a high priority by all workshop participants.…”

A pilot study on potency determination of human follicle-stimulating hormone: A comparison between reversed-phase high-performance liquid chromatography method and the in vivo bioassay

“…For this purpose, animal models are most commonly used. Considering the ethical and political pressures on the use of animals and the nature of the assay, which can be imprecise and is in general costly, there is clearly a need for alternative assays that reduce the use of and/or replace such tests [1][2][3][4].…”