HA蛋白S227N突变对基于新城疫病毒载体的H7N9亚型禽流感疫苗免疫原性的影响

Effect of the S227N substitution in the hemagglutinin on the immunogenicity of Newcastle disease virus vectored-H7N9 avian influenza vaccine

为了评价HA蛋白S227N突变对基于新城疫病毒(NDV)载体的H7N9亚型禽流感疫苗免疫原性的影响,本研究向NDV载体携带的H7N9 HA蛋白中引入S227N突变,用反向遗传学技术拯救重组NDV,评价重组病毒的生物学特性与对鸡的免疫原性。结果显示,表达HAS227N的重组NDV的毒力弱(MDT>120 h),在鸡胚中的病毒效价高(HA效价:512;EID_(50):10^(9.3)/m L),复制性能较强,这些生物学特征与载体病毒及表达野生型HA蛋白的重组NDV相似。S227N突变不影响HA蛋白在重组NDV感染细胞中的表达。此外,表达HAS227N与野生型HA蛋白的重组NDV均能诱导产生较高的抗NDV血凝抑制(HI)抗体;HA蛋白S227N突变能够提高重组NDV免疫鸡的血清转化率,却不能显著提升针对H7N9的HI抗体效价。上述结果表明,HA蛋白S227N突变对基于NDV载体的H7N9亚型禽流感疫苗的免疫原性没有显著的增强作用。本研究对H7N9亚型禽流感疫苗的设计、优化与效力评估有参考意义。

The purpose of this study is to evaluate the effect of the S227N substitution in the hemagglutinin(HA)on the immunogenicity of Newcastle disease virus(NDV)-vectored H7N9 avian influenza vaccine in chickens.The recombinant NDV expressing the HA with the S227N substitution was generated using reverse genetics and its biological characteristics and immunogenicity in chickens were assessed.The results indicated that the recombinant NDV expressing the HAS227N had low virulence(MDT>120 h),high virus titer(HA titer:512;EID_(50):10~(9.3)/m L)and replication capacity in chicken embryonated eggs.These features were comparable to those of the vector virus and the recombinant NDV expressing the wild-type HA protein.The S227N substitution did not change HA expression pattern in the cells inoculated with the recombinant NDVs.Additionally,the recombinant NDVs expressing the HAS227N or the wild-type HA protein induced high hemagglutination-inhibition(HI)antibody titers against NDV.The HA S227N substitution increased seroconversion of chickens immunized with the recombinant NDV,whereas it failed to significantly elevate HI titers against H7N9 virus.In conclusion,the S227N substitution in HA cannot significantly enhance the immunogenicity of NDV-vectored H7N9 vaccine in chickens.This study presented helpful information for the design,optimization and evaluation of H7N9 avian influenza vaccines.