Related Experiment Video
Updated: Jun 26, 2026
Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins
Published on: September 30, 2014
Development of High-Throughput Serum Bactericidal Assays for Bordetella pertussis to Evaluate BPZE1
Peter Goldstein1,2, Tania Gensale3, Shannon Harris1
1ILiAD Biotechnologies, Inc., Weston, FL 33331, USA.
Insights
New assays can measure the immune response to pertussis (whooping cough) vaccines. These assays show that the BPZE1 vaccine generates immunity against both common and emerging pertussis strains.
Area of Science:
- Immunology and Microbiology
- Vaccinology
Background:
- Pertussis remains a global health concern, with pertactin-negative *Bordetella pertussis* strains emerging due to acellular pertussis vaccine (aPV) pressure.
- The live attenuated intranasal vaccine BPZE1 targets multiple antigens, potentially offering broader protection against various *B. pertussis* strains.
Purpose of the Study:
- To develop and qualify high-throughput human complement-mediated serum bactericidal assays (SBAs) for assessing bactericidal activity against *Bordetella pertussis*.
- To evaluate the immunogenicity of the BPZE1 vaccine compared to the tetanus-diphtheria-acellular pertussis (Tdap) vaccine using the developed SBAs.
Main Methods:
- Developed and validated two high-throughput serum bactericidal assays (SBAs) against pertactin-positive and pertactin-negative *B. pertussis* strains.
- Assessed assay accuracy, precision, linearity, and robustness using commercial and clinical trial samples.
- Analyzed serum samples from a phase 2b clinical trial of BPZE1 and Tdap vaccinees.
Main Results:
- The developed SBAs demonstrated good accuracy, precision, and linearity, with high throughput (120 samples/day/analyst).
- BPZE1 induced similar bactericidal activity against pertactin-positive *B. pertussis* as Tdap, despite lower anti-aP antigen IgG levels.
- Crucially, BPZE1 induced significant bactericidal activity against pertactin-negative *B. pertussis*, whereas Tdap did not.
Conclusions:
- High-throughput SBAs were successfully developed and qualified for measuring bactericidal activity against both pertactin-positive and pertactin-negative *B. pertussis*.
- These validated assays are essential tools to support the clinical development of next-generation pertussis vaccines, including BPZE1.
Background/Objectives:
Pertussis, caused by Bordetella pertussis, remains a global health problem, despite high vaccine coverage. In countries with high acellular pertussis vaccine (aPV) coverage, pertactin-negative B. pertussis strains emerged due to vaccine pressure on the sole bactericidal target of aPVs. In contrast, the live attenuated intranasal vaccine BPZE1 induces bactericidal antibodies to multiple antigenic targets that kill pertactin-positive and pertactin-negative B. pertussis strains. Here, we developed two high-throughput human complement-mediated serum bactericidal assays (SBA) using clinical samples to demonstrate bactericidal activity against B. pertussis.
Methods:
Assay accuracy, precision, linearity, range and robustness of the SBAs against pertactin-positive and pertactin-negative B. pertussis strain B1917 were determined using a panel of commercial and clinical trial samples. The assay was used to analyze a cohort of BPZE1 and tetanus-diphtheria-acellular pertussis (Tdap) vaccinee samples at baseline and 28 days post-vaccination from a phase 2b clinical trial.
Results:
Inter- and intra-assay variability of both assays had coefficients of variation for repeatability < 20% and for intermediate precision of <30%. The assays measured titers ranging from ~8 to ~20,000 and showed high linearity (R2 > 0.98) between bactericidal titers and serum dilutions. On clinical samples, BPZE1 induced similar bactericidal activity as Tdap against pertactin-positive B. pertussis, despite inducing lower anti-aP antigen IgG concentrations than Tdap. Additionally, BPZE1 induced serum bactericidal activity against pertactin-negative B. pertussis, while Tdap did not.
Conclusions:
High-throughput SBAs were developed and qualified against pertactin-positive and pertactin-negative B. pertussis, enabling measurement of 120 samples per day per analyst. These assays will support clinical development of next-generation pertussis vaccines, including BPZE1.
