The Pertussis Serological Potency Test collaborative study to evaluate the replacement of the Mouse Protection Test
Evaluatie van de Pertussis Serological Potency Test ter vervanging van de muisbeschermings test middels een internationale ringstudie
26 May 2012, PDF |
34 pages |
van der Ark A, van Straaten-van de Kapelle I, Enssle K, Jadhay S, Olander R-M, van de Donk H, Hendriksen C
RIVM Report 623860008
The Pertussis Serological Potency Test (PSPT) - based on in vitro assessment of the humoral immune response against Bordetella pertussis - was developed as an alternative for the Mouse Protection Test (MPT). A small-scale collaborative study was carried out in five laboratories to evaluate the relevance and reliability of the PSPT. The study has been divided into three separate phases, each with its own objective. A pre-phase study of the antibody detection assay, the 18323-whole cell ELISA (WCE) was included for training purposes. Sixteen serum samples were tested on 5 different days, resulting in significant differences in absorbance and antibody concentrations between the laboratories. In the Phase I study, the intra-assay, inter-assay and inter-laboratory precision of the 18323-WCE was assessed. The 5 participants assayed sixteen other serum pools 5 times on 5 different days. Although a precision of less than 20% was not always established and significant differences in antibody concentrations were found at random throughout the Phase I study, the ranking of the antibody concentrations corresponded well between the laboratories and should warrant a reliable potency estimation of whole cell vaccines (WCV's) in the PSPT. Phase II was a comparative study of the PSPT and the MPT to evaluate the implementation of the PSPT, to demonstrate correlation and to compare the reproducibility and reliability of both tests. Four out of the 5 participant have tested 4 different WCV's twice in the PSPT and the MPT. The mean antibody concentrations per vaccine dose in the PSPT and the survival of mice in the MPT differed significantly within and between the laboratories. Nevertheless, the potencies of the vaccines under test estimated in both test models did not differ significantly (p > 0.05). The PSPT and MPT correlated well in a c2-test of homogeneity within and between the laboratories. The potencies were almost similar (overall ratio = 0.877), but the PSPT is more reproducible and reduces the chance of re-testing due to the smaller 95% confidence intervals. In conclusion, the PSPT is a valid model to estimate the potencies of pertussis WCV's of different manufacturers.