AN ALTERNATIVE POTENCY TEST IN MICE FOR PORVAC®, A SUBUNIT VACCINE AGAINST CLASSICAL SWINE FEVER

Classical swine fever (CSF) is the main sanitary problem of pig farming in endemic regions. Porvac® is a subunit vaccine against CSF with promissory results in clinical trials. Porvac® lots are released with a lethal viral challenge test in pigs. An alternative potency test that measures neutralizing antibodies (NAb) titers in mice was established. The dose-response curve was standardized in the range from 125 ng to 8 ng. The effective dose to induce a NAb titer ≥1:50 in half the immunized mice (ED50) for the reference lot was 28.3 ± 3.6 ng. The reference vaccine lot was stable after four years at 4C and a coefficient of variation of 35% was calculated for the intermediate precision. Another ten vaccines batches tested had a relative potency above 0.9. Nine of these batches also fulfilled the parallelism and linearity tests. The tenth batch did not comply with the linearity criteria. The assay was specific since no response was observed in negative controls. Moreover, the method was sensitive to detect physical changes in the vaccine, as the ED50 increased more than tenfold after thermal stress. Finally, a blind study confirmed the capacity of the method to detect batches with reduced amounts of the active ingredient. © 2022 Institute of Validation Technology. All rights reserved.