National Toxicology Program

National Toxicology Program

UPDATE NewsletterUPDATE NewsletterApril 2015

New method will reduce animal use in pertussis vaccine testing

By Catherine Sprankle

Participants at a March 4-5 workshop, including regulators and vaccine manufacturers, agreed on a new test method that uses fewer animals for pertussis vaccine safety testing, and a plan was proposed for international adoption of the test.

Scientists with the National Toxicology Program (NTP) and international collaborators organized the workshop, which was hosted by the National Centre for the Replacement, Refinement and Reduction of Animals in Research at its headquarters in London.

Interest in alternatives to pertussis vaccines

Acellular pertussis vaccines, which contain proteins purified from bacteria, rather than whole cells, were developed in the 1980s. Prior to marketing these vaccines, manufacturers must confirm the absence of residual pertussis toxin by using the rodent-reliant murine histamine sensitization test, or HIST. There is widespread interest among vaccine manufacturers and animal welfare advocates in finding a nonanimal alternative to the test, because the technically challenging test requires up to 60 animals per test, and the animals experience significant pain and distress.

The International Working Group for Alternatives to HIST, established in 2011, has addressed this issue through a series of four workshops. Participants reviewed available alternatives, recommended studies to evaluate those alternatives, and considered requirements for regulatory acceptance. Scientists with the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM) have participated in the working group from the beginning.

“This ongoing effort serves as an excellent example of a successful collaboration between regulators and industry scientists,” said Dave Allen, Ph.D., who presented a summary of the previous workshops. “Working together to identify valid nonanimal alternatives for biologics testing, this group of experts is making significant progress towards reducing our reliance on animal use.” Allen is a researcher with NICEATM support contractor Integrated Laboratory Systems Inc. (ILS).

Successful workshop series

The 43 international experts who attended the March workshop examined data from a multilaboratory study. The study evaluated an assay that uses a cell line derived from Chinese hamster ovarian tissue to measure pertussis toxin in vaccine samples that contain reference preparations, or specific quantities of added toxin. The experts concluded that the assay worked adequately, and they recommended that vaccine manufacturers begin using the assay alongside current HIST testing to demonstrate its validity for their specific products.

Participants also discussed implementing an approach that would allow manufacturers to waive testing entirely under certain circumstances, and regulatory agency representatives attending the meeting agreed in principle to this suggestion.

Proceedings from the workshop will be submitted to Pharmeuropa Bio and Scientific Notes for publication later this year.

(Catherine Sprankle is a communications specialist with ILS.)

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