Preliminary Study On Thermotolerant Form Of Infectious Bronchitis Attenuated Vaccine

Avian infectious bronchitis(IB)is a kind of acute and highly contagious respiratory disease caused by infectious bronchitis virus(IBV).It can cause chickens growth retardation,and even death.Adult chickens generally do not die after infect IBV,but will cause hens a decline in the quantity and quality of egg,that cause huge economic losses.Vaccination is essential to prevent and control the disease.The infectious bronchitis attenuated vaccines generally have poor heat resistance,the current avian infectious bronchitis virus vaccine stored mainly at-15?-20 ?,it must rely on the system of "cold chains",which make it difficult to transport and use in remote areas.In this study,we mixed heat-resisting protector with the virus and applicated freeze-drying and foam-drying technology to select the vaccine which show the high-temperature stability.In addition to screen resistant protective agent,the drying process optimization,residual moisture determination,aging tests at 37 ? and shelf-time test were studied to obtain infectious bronchitis virus vaccine that have strong immune potency and withstand high temperatures.The study could resolve the unstable problem at room temperature of live vaccine.1 Study on freeze-drying of infectious bronchitis live vaccineIn order to improve the heat resistance of avian infectious bronchitis virus vaccine,the protective agent including sugar,gelatin,EDTA,etc.was screened through single factor test,residual moisture determination of dried vaccine and aging test at 37 ?.After the recipe determined,vacuum freeze drying process was adjusted in order to prepare a vaccine shapes like round cakes,and the surface is smooth,no shrinking,no stratification of the bottom,dried infectious bronchitis virus vaccine have residual water content between 2?3%,viral titers loss within 1.0Lg at 37? for 10 days.In this experiment S3-T4,S3-T9 resistant protective formulations were screened,and viral titers loss in 37? aging test was 0.74Lg and 0.67 Lg respectively.2 Vacuum foam drying research of infectious bronchitis vaccineThe main component of the foam drying protective agents are trehalose,gelatin,EDTA,etc.,by single factor test for each variable composition and ratio,we intend to gain the resistant formula which enhance the infectious bronchitis virus vaccine stability.We screened the thermal protection formulations by considering of morphology,residual moisture content,aging test and shelf-time test.Adjustments of foam drying procedure based on literature and laboratory in order to obtain vaccine which have uniform foam and high 1/2-3/4 vial,control the residual moisture content less than 4%that can stored at room temperature for a long time.The study selected P3,P3-11,P3-13,P3-15 four resistant formula,the residual moisture of vaccines were 2.5%,2.6%,2.8%,2.2%.After 4 months preservation at room temperature,virus titers loss were 0.79Lg,0.85Lg,0.89Lg,0.59Lg relatively.