Evaluatie van Whole Cell-vaccin geinduceerde humorale antilichaamresponsen in de Pertussis Serological Potency Test in relatie met de Muisbeschermingstest

The Pertussis Serological Potency Test (PSPT) has been developed as an alternative for the current MPT. The PSPT is based on in vitro assessment of the humoral immune response against the whole range of surface-antigens of B. pertussis in mice after immunisation with Whole Cell Vaccine (WCV). The concentration of pertussis antibodies in sera is measured in the 18323-Whole Cell ELISA (18323-WCE). In an in-house validation study 13 WCVs were tested in the PSPT and the MPT. Homogeneity of both test systems was proven by means of a modified chi-square test ; potencies were not significantly different (p = 0.95). Compared to the MPT, the PSPT is more reproducible as is indicated by its smaller 95% confidence intervals. Additionally, the immunogenicity of WCVs has been studied in antigen specific ELISAs and in vitro functional test systems to assess correlation with mouse protection. Estimation of WCV-potencies based on the antibody concentration against Pertussis Toxin (PT), Filamentous-Hemagglutinin (FHA) or 69-kDa Outer Membrane Protein (OMP) was not possible due to very low antibody responses which were not vaccine dose dependent. The anti-92-kDa OMP antibody response showed a poor correlation with the MPT, due to scattering. In conclusion, the protection of mice against a lethal intracerebral challenge is not related to a humoral immune response against a single 'protective' antigen, nor restricted to a single immune mechanism, but may be related to a synergistic effect of humoral responses against a wide range of 'protective' and 'non-protective' antigens. The PSPT is therefore a good alternative for the MPT and provides more precise information about immunogenicity, potency and hence on consistency in production of pertussis WCVs.De Pertussis Serologische Potency Test (PSPT) is ontwikkeld als een alternatief voor de huidige Muisbeschermingstest (MBT). De PSPT is gebaseerd op het in vitro bepalen van de humorale afweerrespons tegen het hele scala aan oppervlakte antigenen van B.pertussis bacterie in muizen na immunisatie met kinkhoest whole cell vaccins (WCV). Kinkhoest-antilichaamconcentraties in muizensera wordt bepaald met behulp van de 18323-whole cell ELISA (18323-WCE). Tijdens een 'in-house' validatie studie zijn 13 kinkhoest WCV's in zowel de PSPT als de MBT getest. De overeenkomst van beide testen is aangetoond m.b.v. een chi-kwadraat test ; de werkzaamheid van WCV's in beide testen zijn niet significant verschillend (p = 0.95). Vergeleken met de MBT is de PSPT beter reproduceerbaar, hetgeen tot uiting komt in de kleinere 95% betrouwbaarheidsintervallen. Aanvullend hierop is de immunogeniteit van WCV's in antigeen-specifieke ELISA's en in vitro functionele testsystemen bestudeerd. De schatting van WCV-werkzaamheid op basis van de antilichaam responsen tegen Pertussis Toxine (PT), Filamentous Heam-aggltinine (FHA) of 69-kDa Outer Membrane Protein (OMP) was niet mogelijk door dat deze te laag en niet dosis afhankelijk waren. De antilichaam respons tegen het 92-kDa OMP correleerde niet met de overleving van muizen in de MBT, door te grote fluctuaties. De bescherming van muizen tegen een letale intracerebrale challenge is niet gerelateerd aan de humorale antilichaam respons tegen een specifiek antigeen, noch beperkt tot een afweermechanisme, maar lijkt overeen te komen met een synergistische effect van de humorale afweer respons tegen diverse zogenaamde 'beschermende' en 'niet-beschermende' antigenen. De PSPT is daarom een goed alternatief voor de MBT en geeft bovendien meer en betere informatie over de immunogeniteit, werkzaamheid en consistentie in productie van kinkhoest WCV's

Evaluatie van Whole Cell-vaccin geinduceerde humorale antilichaamresponsen in de Pertussis Serological Potency Test in relatie met de Muisbeschermingstest

De Pertussis Serologische Potency Test (PSPT) is ontwikkeld als een alternatief voor de huidige Muisbeschermingstest (MBT). De PSPT is gebaseerd op het in vitro bepalen van de humorale afweerrespons tegen het hele scala aan oppervlakte antigenen van B.pertussis bacterie in muizen na immunisatie met kinkhoest whole cell vaccins (WCV). Kinkhoest-antilichaamconcentraties in muizensera wordt bepaald met behulp van de 18323-whole cell ELISA (18323-WCE). Tijdens een 'in-house' validatie studie zijn 13 kinkhoest WCV's in zowel de PSPT als de MBT getest. De overeenkomst van beide testen is aangetoond m.b.v. een chi-kwadraat test ; de werkzaamheid van WCV's in beide testen zijn niet significant verschillend (p = 0.95). Vergeleken met de MBT is de PSPT beter reproduceerbaar, hetgeen tot uiting komt in de kleinere 95% betrouwbaarheidsintervallen. Aanvullend hierop is de immunogeniteit van WCV's in antigeen-specifieke ELISA's en in vitro functionele testsystemen bestudeerd. De schatting van WCV-werkzaamheid op basis van de antilichaam responsen tegen Pertussis Toxine (PT), Filamentous Heam-aggltinine (FHA) of 69-kDa Outer Membrane Protein (OMP) was niet mogelijk door dat deze te laag en niet dosis afhankelijk waren. De antilichaam respons tegen het 92-kDa OMP correleerde niet met de overleving van muizen in de MBT, door te grote fluctuaties. De bescherming van muizen tegen een letale intracerebrale challenge is niet gerelateerd aan de humorale antilichaam respons tegen een specifiek antigeen, noch beperkt tot een afweermechanisme, maar lijkt overeen te komen met een synergistische effect van de humorale afweer respons tegen diverse zogenaamde 'beschermende' en 'niet-beschermende' antigenen. De PSPT is daarom een goed alternatief voor de MBT en geeft bovendien meer en betere informatie over de immunogeniteit, werkzaamheid en consistentie in productie van kinkhoest WCV's.The Pertussis Serological Potency Test (PSPT) has been developed as an alternative for the current MPT. The PSPT is based on in vitro assessment of the humoral immune response against the whole range of surface-antigens of B. pertussis in mice after immunisation with Whole Cell Vaccine (WCV). The concentration of pertussis antibodies in sera is measured in the 18323-Whole Cell ELISA (18323-WCE). In an in-house validation study 13 WCVs were tested in the PSPT and the MPT. Homogeneity of both test systems was proven by means of a modified chi-square test ; potencies were not significantly different (p = 0.95). Compared to the MPT, the PSPT is more reproducible as is indicated by its smaller 95% confidence intervals. Additionally, the immunogenicity of WCVs has been studied in antigen specific ELISAs and in vitro functional test systems to assess correlation with mouse protection. Estimation of WCV-potencies based on the antibody concentration against Pertussis Toxin (PT), Filamentous-Hemagglutinin (FHA) or 69-kDa Outer Membrane Protein (OMP) was not possible due to very low antibody responses which were not vaccine dose dependent. The anti-92-kDa OMP antibody response showed a poor correlation with the MPT, due to scattering. In conclusion, the protection of mice against a lethal intracerebral challenge is not related to a humoral immune response against a single 'protective' antigen, nor restricted to a single immune mechanism, but may be related to a synergistic effect of humoral responses against a wide range of 'protective' and 'non-protective' antigens. The PSPT is therefore a good alternative for the MPT and provides more precise information about immunogenicity, potency and hence on consistency in production of pertussis WCVs.V

The St George’s Respiratory Questionnaire revisited: a psychometric evaluation

Purpose The St George’s Respiratory Questionnaire (SGRQ) has clearly acquired the status of legacy questionnaire for measuring health-related quality of life in patients with chronic obstructive pulmonary disease (COPD). The main aim of this study was to assess the underlying dimensionality of the SGRQ and to investigate the added value of the empirical weights used to calculate total scores. Methods The official Dutch translation of the SGRQ was completed by 444 COPD patients participating in two clinical studies. These data were used for secondary data analysis in this study. Three complementary statistical methods were used to assess dimensionality: Mokken scale analysis (MSA), parametric multidimensional item response theory (IRT) and bifactor analysis. Additionally, the original SGRQ weighting procedure was compared to IRT-based weighting. Results The results of the MSA and multidimensional item response theory (MIRT) pointed toward a unidimensional structure. The bifactor analyses indicated that there was a strong general factor, but the group factors did have additional value. Nineteen items performed poorly in the MSA, MIRT analysis or both. Shortening the scale from 50 to 31 items did not negatively impact measurement precision. SGRQ total score and IRT-derived scores correlated strongly, 0.90 for the one-parameter model and 0.99 for the two-parameter model. Conclusion The SGRQ contains some multidimensionality, but an abbreviated version can be used as a unidimensional tool in patients with COPD. Subscale scores should be used with care. SGRQ total scores correlated highly with IRT-based scores, and thus, the weighting methods may be used interchangeably to calculate total scores