In vitro potency assays for nonreplicating veterinary vaccines: comparison to in vivo assays and considerations in...

Each finished batch or serial of veterinary vaccine must be potency tested to assure the quality of marketed product. The potency assay must be correlated to efficacy in the target species. Potency assays of nonreplicating vaccines have traditionally measured the immune response to the vaccine in host or laboratory animals by serology or protection from challenge. Such tests are expensive, time-consuming, and raise animal welfare concerns. As disease agent protective antigens are described, in vitro techniques for quantitating them can be applied to vaccine potency measurement. However, in many cases the immunological adjuvants critical to the efficacy of the biological interfere with in vitro antigen quantitation techniques. The development of techniques that remove or compensate for the effect of adjuvants on the assays, sham vaccines containing no antigen, reference preparations containing a proven protective immunogen dose, characterization of the immunological reactants, and appropriate design and data analysis have contributed to the development of rapid, reproducible, humane, and relatively inexpensive in vitro potency assays to be used in the evaluation of veterinary biologicals.