H9N2亚型AIV NA基因多聚腺苷酸化信号位点对病毒复制的影响

Effect of polydenosine signal site of H9N2 AIV NA gene on virus replication

H9N2亚型禽流感病毒NA基因vRNA 5′端的多聚腺苷酸化信号位点具有多样性,突变发生时,该位点失去与聚合酶的结合能力或结合能力减弱,阻碍多聚腺苷酸化过程,影响病毒mRNA的转录过程。为探究H9N2亚型禽流感病毒NA基因5′端多聚腺苷酸化信号位点处5个或6个连续的尿嘧啶(U_(5)或U_(6))碱基对病毒生物学特性的影响,以一株四川分离株A/Chicken/China/Sichuan/CQY/2014(H9N2)为骨架的反向遗传系统构建突变株。结果显示,含U_(5)的H9N2突变株(rCQYU_(5)-H9N2)的血凝效价、TCID_(50)和EID_(50)滴度均高于含U_(5)的H9N2突变株(rCQYU6-H9N2),但生长曲线无显著差异,表明H9N2 NA基因5′端多聚腺苷酸化信号位点U_(5)或U_(6)结构均不影响病毒的拯救,但U_(5)有助于提高病毒在鸡胚与细胞中的复制滴度。本实验研究结果可为H9N2亚型禽流感病毒的复制机理等研究提供参考。

The polyadenylation signal site at the 5′end of the NA gene vRNA of H9N2 subtype avian influenza virus is diverse.When mutated,this site loses its binding effect with polymerase or leads to weakened binding ability,it blocks the polyadenylation process and affects the transcription process of viral mRNA.To explore the effect of 5-terminal polyadenylation signal sites(five or six uracil bases,U_(5) or U_(6))of NA gene on the H9N2 subtype of avian influenza virus rescue,a series of mutants were constructed with a reverse genetic technology based on a A/Chicken/China/Sichuan/CQY/2014(H9N2)strain which was isolated in Sichuan Province.The results showed that both of the hemagglutination titer,TCID_(50) and EID_(50) of rCQYU_(5)-H9N2 strain were higher than those of rCQYU_(6)-H9N2 strain,while the growth curve had no significant difference.The results indicated that the structure of U_(5) and U_(6) at the 5′terminal of the H9N2 NA gene had no effect on the rescue of the virus,while the five consecutive uracil bases were more favorable for the titer of the H9N2 AIV on MDCK cells and chicken embryo.The results of this experimental study provided a certain reference for the research on the replication mechanism of H9N2 subtype avian influenza virus.