Comparison of in vivo and in vitro methods for potency assay of Bordetella Pertussis vaccines

  Background: One of the main applications of laboratory animals is in quality control of vaccines. In vitro methods have been suggested as alternatives to in vivo animal testing because of its special problems.   Objective: The aim of this study was to compare in vivo and in vitro methods for potency assay of bordetella pertussis vaccines.   Methods: This experimental study was performed on a group of mice using different lots of reference or whole cell pertussis (wP) vaccine that were provided by Razi Vaccine & Serum Research Institute at this Institute in 2010. Mice were killed after immunization and their peritoneal cavities were lavaged and were cultured with challenge strain to determine nitrite concentration produced from macrophages and to assess immune response. Data were analyzed by comparison with a standard curve of sodium nitrite (r=0.924).   Findings: There were significant differences between results of in vivo and in vitro methods using different lots of wP vaccines . Macrophages from mice immunized with wP vaccine produced higher levels of nitric oxide than macrophages from mice of control groups.   Conclusion: With regards to the results, nitric oxide induction assay is more sensitive than Kendrick assay in potency assay of vaccine and provides the possibility of assessing low-titre vaccine. Therefore, it can be used as an alternative to reduce animal testing.