Evaluation of various chemical stabilizers on the stability of avian infectious bronchitis vaccine

Infectious bronchitis vaccine (IBV) is a live attenuated viral vaccine which is sensitive to the environmental changes. In order to maintain their potency and efficacy, stabilizer agents are usually added to the lyophilized vaccines during preparation process, stabilizing the vaccine throughout the manufacturing, storage, and administration. This study aimed to determine the efficacy of four different stabilizers on IBV. Four different stabilizers including lactalbomin–lactose (LL), lactalbumin–sucrose (LS), lactose–peptone (LP) and gelatin–sorbitol (GS) were used to prepare lyophilized vaccines. The vaccine was titrated before and after lyophilization. To determine accelerated stability (based on OIE instruction), the vaccines were titrated after 7 days incubation in 37ºC. Residual moisture of lyophilized vaccines was measured by Karl-Fisher method. Furthermore, the stability of the vaccines in 4ºC was measured over 36 months at three months intervals. All experiments were repeated for three batches of the vaccine. The results showed that acceptable titer of the vaccine was observed with four stabilizers. Residual moisture found to be in appropriate limit, ranged from 1.42-2.72%. Following seven days incubation in 37ºC, titer reduction of the vaccine with lactose-lactalbomin was the lowest. The results showed that in the end of this period, the vaccine with LL has the highest titer. In conclusion, it seems that lactose-lactalbomin stabilizer provided good protection to IBV under lyophilization condition and maintenance of the vaccine for long time in 4ºC.