Adaptive Passage Of YF Vaccine Strain 17D On Vero Cells

To obtain the adaptive strains of YF 17D vaccine virus on Vero cells, YF vaccine virus derived from chicken embryos was cultured on Vero cells and selected through plague selection, and then adapted to Vero cells. The stability of YF 17D adaptive vaccine virus was studied.YF vaccine virus on SPF chicken embryos was adapted to Vero cells on monolayers with 0.1 PFU/cell of MOI at 37℃. Four adaptive strains of YF 17D vaccine virus on Vero cells (YFV-Vero(5)-Al, YFV-Vero(5)-A2, YFV-Vero(5)-B1 and YFV-Vero(5)-B2) were obtained by plague selection. The four adaptive strains of YF 17D can be neutralized by YF 17D monkey immune serum. In the process of adaptation, the virus titre was stable and beyond 6.9 Lg PFU/ml, the size of plagues of all passages had no change, and peak cytopathic effect occurred between 5~7 days. The test of neutralization was done on both BHK.-21 and Vero cells matrix, the immune sera of rabbits and mice can neutralize viruses of YF vaccine derived from chicken embryos with different lot numbers, and the titre of neutralization antibody was between 1:1280~1:5120. It suggests that the four adaptive strains of YF 17D vaccine virus on Vero cells have good immunogenicity.The results of the preliminary experiments show that the virus titre of the four adaptive strains of YF 17D on Vero cells is high and stable, the titre of neutralization antibody is high, and the immunogenicity of them is excellent. In future, the test of neurological toxicity in monkeys needs to be performed to confirm the hereditary stability of the virus strains, and the full sequences of them need to be detected to analyze their genetic stability.