Development Of The Lyophilized Heat-resistant Stabilizers Of Lyophilized Newcastle Disease Virus Vaccine (Clone30 Strain)

Newcastle disease is one of the most infectious diseases in poultry industry, and avirulent strain live vaccine against this disease is the most widely used vaccines. Lyophilized live vaccine possesses a considerable proportion in the market of poultry vaccines in China mainland. At present, conventional stabilizers used in vaccine in our country are composed of sugar, skimmed milk, glutin and so on. Because of simple combination of conventional stabilizers and poor heat-resistant protection, the live vaccines only preserved 3-6 months in 2-8℃, so, it commonly preserved in -15℃. However, the development of animal vaccinal stabilizers have lagged in our country, and shortage of equipments in cold chains restrcted long-distance transfer and long time storage of live vaccine, which made efficiency of live vaccine easily lost. New forms of heat-resistant lyophilized stabilizers have been applied in live vaccines in developed country, however, the techniques are commercially a secret.Because of short storage term for lyophilized live Newcastle disease vaccine of in 2-8℃, exploring the new forms of lyophilized heat-resistant stabilizers is of necessity. The composition and mixed proportion of heat-resistant stabilizers and optimal freeze-drying curves procedures were explored by orthogonal and single factor experiments in NDV Clone30.Three groups heat-resistant stabilizers, named C8,14 and 38, were developed in the first round test, and tested in production of live vaccine of NDV Clone30. The results indicated only a slight decrease in efficiency during the process of freeze-drying in the heat-resistant stabilizers groups, in contrast, control group reduced by 100.5EID50. The stabilizers groups of C8 and 38 were further optimized with freeze-drying curves. C8 and 38 were used in the production test, which took on good shape and shorter freeze-drying term (approximate 40 h).In the tests of storage term for C8 and 38, when production store for 3 weeks at 37℃, there were 15.7% and 16.2%, respectively, reduction in the two test groups; when production store for 30 days at room temperature, there were 7.9% and 10.1%, respectively, reduction in the two test groups; and only a little virus loss when production store at 2-8℃for 9 months. However, when product stored for only 20 days at room temperature, 24.1% virus has reduced in the control group. The results indicated stabilizers of C8 and 38 were of good heat-resistance and showed promise in application of production.In conclusion, two groups of stabilizers, C8 and 38, were developed in this study, which provided useful reagents for reforming the conventional production procedures, reducing production cost, improving production quality and for reassement scientific data in application of new veterinary bio-products.