Use of recombinant influenza vaccines expressing exogenous miRNAs for increased vaccine production

Abstract

Abstract Vaccination remains the most effective means by which influenza virus infection can be controlled. Traditionally vaccine production has focused on egg-based technology. Increasingly cell culture-based vaccine production is being used to improve preparedness. Cell cultured based production methods offer significant advantages over traditional egg-based strategies by allowing (i) rapid scale-up (ii) elimination of allergic egg components and (iii) circumvention of issues relating to egg-adaption. Our aim was to improve influenza vaccines and preparedness through the establishment of mammalian cell (Vero)-based vaccines using plasmid-based recombinant flu constructs expressing exogenous miRNA19 (flu-miR19), a regulator of key host anti-viral pathways that has previously been shown to modulate influenza virus replication. We successfully rescued recombinant influenza viruses expressing miR19 using reverse genetics; validated expression of miR19 and showed increased virus replication in vitro that corresponded with increased HA titres and matrix gene expression. Knockdown of miR19 host target genes was confirmed through qRT-PCR to validate the mechanism of action. This new influenza vaccine platform is scalable and can be merged with existing production technology to offer rapid clinical translation and improve vaccine quality and production times. In summary, silencing of anti-viral host genes using a flu-miR resulted in an increase of influenza vaccine and HA antigen yield. We now plan to further augment antigen yield by propagating these viruses in enhanced Vero cell vaccine substrates.