A sensitive and specific serology test for evaluating potency of whole cell Pertussis vaccines

Immport Therapeutics, Inc., Irvine CA

Investigators

Abstract

Whooping cough (pertussis) is a highly contagious respiratory disease caused by the Gram-negative bacterium, Bordetella pertussis. In most of the world, infants receive a whole cell pertussis (wP) vaccine in conjunction with diphtheria and tetanus (DTwP). With tens of millions of doses of DTwP administered globally each year, evaluation of vaccine potency is a critical step for manufacturers toward vaccine release. First established in 1947 and still in use today, the Kendrick assay is the method of evaluating wP potency. As a labor intensive and highly variable mouse intracerebral challenge protocol, the Kendrick assay constitutes a bottleneck in DTwP vaccine release. There have been efforts to replace the Kendrick assay with a pertussis serology potency test (PSPT) based on a whole pertussis bacteria ELISA, but the PSPT suffers from issues of sensitivity and variability. Antigen Discovery, Inc. and Dr. Nicholas Mantis and colleagues at the Division of Infectious Diseases, Wadsworth Center, New York State Department of Health are collaborating in an effort to develop a PSPT based on discovery of new B. pertussis antigens that may serve as indicators of wP vaccine potency. In the proposed study, a B. pertussis proteome microarray will be developed to identify serological markers associated with wP vaccine potency in mice immunized with DTwP at full potency or degraded potency due to thermal stress. Pilot studies have already demonstrated that certain antigen-specific IgG responses indicate vaccine stability, while others indicate instability. We hypothesize that a B. pertussis proteomic screen of antisera from mice vaccinated with potent versus subpotent DTwP preparations will reveal B. pertussis antigens that could serve as reliable potency indicators and, ultimately, serve as the basis of a multiantigen array to replace the Kendrick assay. To accomplish this, mice will be immunized with DTwP either stored according to protocol (4ºC) or subjected to an accelerated decay protocol by extreme thermal stress (60ºC , 80ºC or 100ºC for 60 min). Baseline and post-immunization sera will be tested using B. pertussis proteome microarrays to identify IgG response associated with the mice’s ability to clear B. pertussis bacteria by 4 days after intranasal inoculation with 5x106 CFU of B. pertussis 18323. A sample-sparing multiplex Luminex-based PSPT prototype will then be developed using the antigens identified as indicators of wP vaccine stability and/or instability. The prototype assay will be optimized, qualified and tested in an independent set of sera from mouse DTwP immunization experiments with or without thermal stress. If successful, we will follow with an SBIR Phase II study, where the prototype Luminex-based PSPT will be transferred to a qualified ELISA or CLIA automated assay format and developed under all of the Quality Assurance and Regulatory Affairs requirements for submission of the potency assay to regulatory bodies. In a path toward commercialization, our novel antigen-specific PSPT will be of interest to members of the PSPT consortium within the Developing Countries Vaccine Manufacturing Network (https://dcvmn.org/pspt-consortium/), which includes all of the major manufacturers of wP-containing vaccines and expressed interest in replacing the Kendrick Test with a reliable PSPT.