The International Scientific Workshop on "Potency Testing of Veterinary Vaccines for Animals: The Way From in Vivo to in Vitro, was held in Langen, Germany in December 2010". Before being placed on the market, inactivated vaccines are predominantly tested in vivo, mainly in laboratory animals. In recent years substantial efforts have been made either to modify these animal tests in order to reduce the number of required animals and the stress imposed on them (Refinement) or to completely replace these experiments by in vitro tests. The acceptance of these tests differs considerably among vaccine manufacturers and licensing authorities. It is thus understandable that vaccines manufacturers hesitate to adopt the new test methods. This international scientific workshop aimed to promote further progress. It was attended by more than 130 participants from industry, academia and regulatory authorities from some 22 countries around the world. The current state of knowledge of replacement of in vivo tests was recapitulated, including examples of its successful implementation as well as still existing hurdles. Advantages and disadvantages of existing replacement approaches were presented and discussed. Proposals for new ways to ensure the quality of veterinary immunology medicinal products (IVMPs) were made. The hurdles to be overcome whenever the 3Rs should be implemented in the potency testing of inactivated veterinary vaccines were identified and discussed and a proposal for a road map for future steps towards in vitro testing was made.
