A single immunogenicity assay for testing potency of combination DTaP vaccines: Simultaneous quantitation of anti-DT, anti-TT, anti-PTxd and anti-FHA antibodies in Guinea-pig serum with a Luminex®-xMAP® bead-based serological assay

The diphtheria toxoid (DT), tetanus toxoid (TT), and acellular pertussis (aP) single immunogenicity assay (DTaP SIA) is a Luminex®-xMAP®-bead-based multiplex immunoassay for estimating the potency of DTaP pediatric combination vaccines in guinea pigs. This manuscript describes the validation of this assay for the simultaneous quantitation of anti-diphtheria toxoid (anti-DT), anti-tetanus toxoid (anti-TT), anti-pertussis toxoid (anti-PTxd), and anti-filamentous hemagglutinin (anti-FHA) antibodies in guinea pig serum following injection of a DTaP vaccine formulation. The results were expressed in arbitrary units/mL (AU/mL) using reference serum for comparison. Specificity was demonstrated by ≥ 75% homologous and ≤25% heterologous inhibition for all the antigens. The results were linear for anti-DT, anti-TT, anti-PTxd and anti-FHA antibodies. Accuracy was demonstrated with recovery of between 80% and 120% for all four antibodies. The relative standard deviation of repeatability was ≤20%. The results demonstrate that this SIA can be used for the linear, accurate, and precise simultaneous detection of all four antibodies, based on both the ICH Q2 and the EMA guidelines on bioanalytical method validation.