In a significant breakthrough for vaccine research, a flu jab grown in plants has passed two large-scale clinical trials. Researchers extracted virus-like particles from tobacco plants to create the inoculation.

The boffins used native Australian tobacco relatives that were genetically modified to create the viral proteins. The two trials involved nearly 23,000 people and the results indicated that the plant-derived vaccines are just as safe as current flu vaccines.

The influenza virus poses fresh problems for vaccine developers every year as it constantly shapeshifts. This is a massive undertaking and researchers have been crying out for an upgrade to the current technology.

The breakthrough is the largest ever demonstration of the potential to produce vaccines using plants.

“This is the first time a plant vaccine has been tested in a [human] clinical trial,” John Tregoning, an infectious disease researcher from Imperial College London, said about the results. “It is a milestone for this technology and sows the seeds for other plant-based vaccines and therapeutics.”

The development promises to be a huge boost to the annual fight against influenza, as plants can be mass-engineered to produce viral proteins at scale. Currently, most influenza vaccines are made using virus particles grown in chicken eggs or lab-grown cells.

The scientists used an Australian relative of the tobacco plant, Nicotiana benthamiana, engineered to produce just the outer shell of influenza viruses. These virus-like particles are then extracted and purified to make a flu vaccine.

In their paper published in The Lancet, the scientists say that their plant-based system can produce the first doses of a newly designed flu vaccine within two months of identifying an emerging influenza strain.

The results are hugely promising but the researchers still have to secure regulatory approvals for the vaccine, so it may be some time yet before plant-grown vaccines bear fruit.

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