Uses of Single Dose Dependent and Relative Potency Assays for Evaluation of Inactivated Fowl Cholera Vaccine

Abstract

Fowl cholera is a septicemic respiratory complex caused by Pasteurella multocida, widely distributed in poultry and other avian species and of major economic importance. A total of 37 different inactivated Pasteurella multocida vaccines from different sources either locally prepared or imported from different sources were comparatively tested for relative potency following both single dose and booster dose vaccination assays. The study objective was to minimize the time factor exhausted in the evaluation processes of the inactivated fowl cholera vaccines. So it is planned to compare between single and booster dose vaccinations and their related potency. Correlation between protection associated with the single dose and booster dose vaccination were evaluated and average requirement for protection was 43.7% in single dose vaccination assay compared to 76.2 % associated with booster dose vaccination assay. In the same concern, the correlation between both assays for the seroconversion was estimated using ELISA and the minimum requirement was 1.8× cut off value in the single dose vaccination assay compared to 2.25× cut off value in the booster dose vaccination assay. In conclusion, single dose vaccination assay could be valuable in the evaluation of inactivated fowl cholera vaccines through determination of protection indices and/or estimation of humoral immune response if the above mentioned data is considered.