miRNA-Mediated Viral Attenuation Gives Vaccines a Boost

With all the recent talk of swine flu and pandemics, you might be wondering how the development of new flu vaccines is coming along. In an example of impeccable timing, researchers at the Mount Sinai School of Medicine now report that they’ve attenuated, two strains of the influenza A virus, the culprit behind swine, avian, and—let’s not forget—human flu. The team took advantage of miRNAs silencing prowess and instances of species specific expression to show that the miRNA silencing can be very complementary to current attenuation approaches, improving vaccine safety and broadening the suitable age range those receiving vaccines.

Although miRNA-mediated viral attenuation had been performed previously on a few viruses, it hadn’t been tried with influenza A until now. To do this, the researchers popped miRNA response elements (MREs) for miR93 into the open reading frames of the nucleoprotein genes of H1N1 and H5N1 influenza A strains. The team went with MREs for miR93 since they’re endogenously expressed in humans and mice, but not in birds. This way, the viruses could be propagated in chick embryos, but silenced or weakened in human and mouse cells.

The scientists think this approach could easily be adapted for use with other influenza A strains. Also, with the appropriate MREs, modified viruses could be propagated in tissue culture cells instead of chick embryos. Get the full boost at Nature Biotechnology, May 2009.