Construction of microRNA Let-7b-mediated recombinant influenza A (H1N1) virus with mutated PB1 / 医学研究生学报

ABSTRACT

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 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.