Influence of Accelerated Temperature on Thermal Stability of Inactivated Oil Based Vaccines

Accelerated thermal stability of vaccines during shelf life has vital impact on its potency. Temperature directly affects the stability of the vaccines and degradation of immunogen depends upon the storage and environmental conditions. The current study was undertaken to evaluate the potency of three different inactivated oil based commercial vaccines under artificially induced thermal conditions such as 4°C, 24°C, 36°C and 45°C. The vaccines were analyzed for their viscosity, density, pH, stability, particle distribution and serological potency after 10, 20 and 30 days. It was revealed that vaccines stored for 30 days at 4°C upto 24°C showed significantly better physiochemical response and in vivo serological potency (p>0.05) as compared to vaccines stored for 30 days at 36°C and 45°C (p<0.05). Otto ND showed significantly better emulsion stability even under accelerated temperature at 45°C for 30 days (p>0.05) as compared to Gallimune and Medivac (p<0.05). The density of Medivac was stable under thermal stress conditions even at 36°C for 30 days (p>0.05) as compare to Otto ND and Gallimune vaccine (p<0.05).

It is concluded that inactivated oil based ND vaccines can resist elevated thermal stress up to 36°C for 30 days without any ill effect on physiochemical properties of emulsion and decline in serological potency. The vaccines showed significant deterioration physically at temperature >30°C when stored for 30 days whereas, immunogenic response was protective with minimal uniformity. However, above vaccine could be used for effective immune-prophylaxis in poultry.