title: An international collaborative study of the effect of active pertussis toxin on the modified Kendrick test for acellular pertussis vaccines.
abstract: Speculation that the Japanese modified intra-cerebral challenge assay, which is used in several countries for control of acellular pertussis vaccines, depends on the presence of small amounts of active pertussis toxin led to an assumption that it may not be appropriate for highly toxoided or genetically detoxified vaccines. Consequently, at the recommendation of a World Health Organisation AD Hoc Working Group on mouse protection models for testing and control of acellular pertussis vaccine, the effect of pertussis toxin on the modified intra-cerebral challenge assay (modified Kendrick, MICA) was evaluated in an international collaborative study. Results of this study showed that for genetically detoxified vaccines both with and without active pertussis toxin the MICA clearly distinguished mice vaccinated with acellular vaccines from unvaccinated mice and gave a significant dose-response relationship. However, vaccine samples containing active pertussis toxin (5 or 50 ng/single human dose) appeared to be more potent than the equivalent sample without active pertussis toxin. Similar results were also given by two respiratory infection models (intranasal and aerosol) included in the study. The results also indicated that the effect of pertussis toxin may vary depending on mouse strain.
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Hertfordshire EN6 3QG, UK. Electronic address: Dorothy.Xing@nibsc.org.
authors.forename: Dorothy
authors.initials: D
authors.lastname: Xing
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Hertfordshire EN6 3QG, UK.
authors.forename: Rose
authors.initials: R
authors.lastname: Gaines Das
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Hertfordshire EN6 3QG, UK.
authors.forename: Alex
authors.initials: A
authors.lastname: Douglas-Bardsley
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Hertfordshire EN6 3QG, UK.
authors.forename: Catpagavalli
authors.initials: C
authors.lastname: Asokanathan
authors.affiliation: National Institute for Biological Standards and Control, Potters Bar, Hertfordshire EN6 3QG, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Corbel
mesh_terms: D000818:Animals; D007391:International Cooperation; D051379:Mice; D037342:Pertussis Toxin / Q000276:immunology*; D010567:Pertussis Vaccine / Q000276:immunology*; D022282:Vaccines, Acellular / Q000276:immunology*
chemical_list: D010567:Pertussis Vaccine; D022282:Vaccines, Acellular; D037342:Pertussis Toxin
keywords: Acellular pertussis vaccine; Pertussis toxin; Potency