A practical validation approach for virus titer testing of avian infectious bursal disease live vaccine according to current regulatory guidelines.

The method for virus titer determination of avian infectious bursal disease (IBD) live vaccine, developed long before regulatory validation guidelines is a cell culture based biological assay intended for use in vaccine release testing. The aim of our study was to perform a validation, based on fit-for-purpose principle, of an old 50% tissue culture infectious dose (TCID(50)) method according to Guidelines of the International Cooperation on Harmonization of Technical Requirements for Registration of Veterinary Medicinal Products (VICH). This paper addresses challenges and discusses some key aspects that should be considered when validating biological methods.