Stability of live attenuated classical swine fever cell culture vaccine virus in liquid form for developing an oral vaccine

摘要

Classical swine fever (CSF) is an important viral disease of pigs and controlled by vaccination. Unorganised backyard and wild pigs are difficult to vaccinate by needle vaccination. Here we formulated liquid vaccines using an Indian CSF cell culture vaccine virus and four stabilisers and evaluated their stability at 4 degrees C, 25 degrees C and 37 degrees C up to 24 h for use as oral vaccine. The stabilisers were Lactalbumin hydrolysate-Trehalose, Lactalbumin hydmlysate-Trehalose-Gelatin, Lactalbumin hydrolysate-Lactose-Sucrose and Lactalbumin hydrolysate-Sucrose. The liquid vaccines, with or without stabilisers, were stable at 4 degrees C up to 24 h, whereas, a drop of one logio titre was observed at 25 degrees C during the same period. At 37 degrees C, the virus titre diminished by only one logio with the Lactalbumin hydrolysate-Trehalose (LT) stabiliser up to 24 h compared to two log(10) losses in virus titre with other stabilisers and virus control. We therefore conclude that for developing a CSF oral vaccine, the vaccine virus in liquid form can be used directly during the winter, whereas for developing the oral vaccine for summer, the LT stabiliser would provide maximum stability to the virus to withstand the warm temperature while maintaining adequate therapeutic titre for inducing a protective immune response.