.17 D Yellow Fever Virus In The Adaptive Passages On Chicken Embryo Cells And Their Associated Characteristics,

Yellow fever vaccine (YFV) has been used commercially since 1936. It has been considered as one of the most effective and the safest Arbovirus vaccines by now, which having been used safely more than 60 years around the world. However, the yellow fever epidemic hasn't been controlled successfully by YFV in Africa and south America,for the vaccine can not cover all vulnerable populations, And what's more, people begin to pay more attention to its adverse reactions.Yellow fever vaccine produced in chicken embryo, so it is difficult to maintain effective immunogenicity to obtain good purity in the follow-up purification process .In this study, we used chicken embryo fibroblasts(CEF) as medium instead of chicken embryo to not reduce the immunogenicity of YFV while reducing chick embryo impurity, and propagated 10 passages ,for investigating the influence of the different medium towards the working seed in the aspects of biological characters and genetic stability, and then providing some basis data for the further study of manufacture of the YFV with the CEF.First of all, we chose two different seeds, one was international standard of YFV 99/616-CE (BTBP code), the other was our native seed 2008(54) 01 (54) 5#( BTBP code). Both of them came from the same strain of 17D, and came from the seed of 17D204,them were identificated by identity test.The two seeds were blindly passed respectively for 10 passages in CEF and they were marked as 99/616-passage virus and YFVBJ-passage virus .We respectively investgated the passages of the two seeds for the biologlogical character and genetic stability , including the virus titer,LD50,average survival time in mouse,plaque size,immunogenicity,hybridprotein and part of nonstructural gene order detection.Experimental results showed that:一: Viral titers of two virus strain subculture species have decreased tendency, but all titers are higher than 5.0 lgPFU/ml, there is no significant difference between the various passages.二: LD50 in mouse of two virus strain subculture species have decreased tendency, but except 99/616-1 all titers are higher than 5.0 lgLD50/ml, there is no significant difference between the various passages.三:There is no significant difference between the passages of two virus strain in average survival time and immunogenicity in mice .四: Plaque size of two virus strain subculture species have decreased tendency, there is significant difference between part of the various passages.五:Analysis of non-structural gene NS1 showed no significant difference between various passages. Although changed the culture medium, these results suggested that our yellow fever vaccine working viurs seed has good stability in terms of the relevant characteristics of biological and genetic sequences.In conclution: This study has completed the adaptive passage of our working virus seed and 99/616 international standard of YFV in the chicken embryo fibroblast cell ,and preliminary investigation has been done on the effect of biologlogical characteristics and genetic stability caused by medium change. Except the virus plaque size differed significantly, the passage virus of two virus strain show good stability. These works provide scientific data for the future study in using chicken embryo fibroblasts as substrate to produce yellow fever vaccine.