Preparation and heat resistance study of porcine reproductive and respiratory syndrome virus sugar glass vaccine

To improve the preservation period without cold-chain of the live attenuated vaccine of porcine reproductive and respiratory syndrome (PRRS), a set of thermostable formulations composed of trehalose, tryptone and other protectants were dried by vacuum foam drying (VFD) along with PRRSV solutions. In the 37 °C and 45 °C resistance ageing test, the dried foam vaccine showed significant thermostability, and the virus titer lost 0.8 Log10 at 37 °C for 4 months, 1.0 Log10 at 45 °C for 25 days. Furthermore, the foam vaccine could be stored at 25 °C for at least one year. Besides, the vaccine preserved in 37 °C, 25 °C and 4 °C for 3 months were inoculated on 20-days old piglet, and the serum titer was monitoring by ELISA kit. Inoculated two weeks later, the ELISA titer were all qualified and had the similar level compared to the commercial vaccines of the lyophilization dosage.