表达双拷贝H7N9亚型禽流感病毒HA基因的重组新城疫病毒免疫原性的评价

Immunogenicity of a recombinant Newcastle disease virus expressing dual-copy HA gene of avian influenza virus H7N9

为评价新城疫病毒(NDV)载体携带的外源基因大小对其免疫原性的影响,将2个拷贝的H7N9亚型禽流感病毒HA基因插入NDV的P与M基因之间非编码区最佳插入位点,构建重组NDV并评价其生物学特性及对鸡的免疫原性。结果显示,表达单、双拷贝HA基因的重组NDV与亲本株在鸡胚中的复制水平均相似,而携带双拷贝HA基因使重组NDV诱导鸡产生的NDV抗体显著下降;表达双拷贝HA基因的重组NDV的HA蛋白表达量明显提高,但其诱导鸡产生的H7N9血凝抑制、IgG抗体水平均与表达单拷贝HA基因的重组NDV相当。结果表明,在NDV的P和M基因之间插入双拷贝HA基因能够显著提高HA蛋白表达量,但却使重组NDV在鸡体内的复制能力下降,而不能提高NDV载体疫苗诱导机体产生的H7N9特异性抗体应答的水平。本研究对NDV疫苗载体的构建和优化具有重要参考意义。

To evaluate the impact of foreign gene size on immunogenicity of Newcastle disease virus(NDV)-vectored vaccines,two copies of the hemagglutinin(HA)gene of avian influenza virus(AIV)of the H7N9 subtype were inserted in the non-encoding region between the phosphoprotein(P)and matrix protein(M)genes,the optimal insertion site for foreign genes in NDV.The recombinant NDV carrying dual-copy HA gene was constructed and its biological characteristics and immunogenicity in chickens were evaluated.The results indicated that,replication capacity of the recombinant NDVs carrying single-or dual-copy HA gene in embryonated chicken eggs was similar as their parental virus,whereas increase of HA gene copy in NDV had generated a significant reduction of NDV-specific antibodies in chickens.In addition,although the recombinant NDV carrying dual-copy HA gene can express the HA protein at a higher level,this virus elicited comparable levels of H7N9-specific hemagglutination-inhibition and IgG antibodies in chickens as the recombinant NDV harboring single HA gene.In conclusion,insertion of dual-copy HA gene between the P and M genes of NDV significantly elevated HA protein expression but reduced replication capacity of the recombinant NDV in chickens.Therefore,increase of HA gene copy in the NDV-vectored vaccine cannot enhance antibody response against H7N9 subtype AIV in chickens.This study provided important information for generation of NDV-vectored vaccines.