MicroRNA Let-7b介导甲型流感突变型PB1重组病毒的构建

Construction of microRNA Let-7b-mediated recombinant influenza A( H1N1) virus with mutated PB1

目的疫苗是预防流感所致疾病的最有效方法,MicroRNA介导的基因沉默机制为构建新型疫苗提供了新思路。文中旨在构建包含装载有miRNA Let-7b结合靶位PB1基因的甲型流感重组病毒。方法比对A/Nanjing/108/2009H1N1的PA、PB1、PB2与let-7b的靶序列选定PB1基因为最优序列后,通过基因突变,插入Let-7b的结合靶位;构建p DP2000重组表达载体,设计p DP-mu-PB1,同时设计对照组p DP-sclb-PB1,并与其余7个质粒共转染MDCK细胞和293T细胞拯救病毒;留取上清接种鸡胚尿囊腔,血凝法检测病毒,TCID50检测病毒滴度;提取病毒RNA,采用RT-PCR扩增病毒c DNA,通过琼脂糖凝胶电泳和核苷酸序列分析鉴定病毒。结果选择PB1片段最优序列(位置83 bp-107 bp),突变片段改变了3个氨基酸,同时有3个碱基不能与Let-7b靶序列配对;酶切鉴定重组质粒构建正确;重组病毒miRT(miRNA target elements)-H1N1和scramble(scbl)-H1N1的血凝效价分别为1∶32和1∶64,病毒滴度为4.68×105TCID50/m L和7.94×104TCID50/m L;测序确认突变病毒包含目的片段。结论构建成功重组病毒株,为进一步的毒力评估实验奠定了基础。

Objective Vaccination is a most effective method for the prevention of severe diseases caused by pandemic influenza and microRNA （ miRNA） mediated gene silencing has offered a novel approach to the construction of new vaccines.Our study aimed to construct a recombinant influenza A （ H1 N1 ） virus with the PB1 gene that carries the target fragment of miRNA Let-7b. Methods After comparing the sequence of the A/Nanjing/108/2009 H1N1 viral fragments with that of Let-7b, we selected PB1 as the optimal gene sequence, inserted the Let-7b binding target gene into PB1, ligated the modified fragments with pDP 2000, and named the recombinant plasmids pDP-mu-PB1 and pDP-sclb-PB1, respectively.We co-transfected the MDCK and 293T cells with the recombinant and other seven plasmids and injected the supernatant into the allantoic cavity of the chickenembryo for virus propagation, followed by detection of the virus by hemagglutination （ HA） assay and measurement of the viral titer by TCID50 .We amplified the viral cRNA by RT-PCR and identified the viruses by agarose gel electrophoresis and nucleotide sequence analysis. Results PB1 was the optimal sequence （ 83 bp -107bp） for the attenuation of viruses.The HA-titers of miRT-H1N1 and scbl-H1N1 were 1∶32 and 1∶64, and their viral loads＆nbsp;were 4.68 ×105 and 7.94 ×104 TCID50/mL, respectively.Nucleotide sequence analysis showed the expected fragment in the rescued virus. Conclusion A recombinant strain vaccine was successfully constructed, which has laid the foundation for fur-ther assessment of virulence.