A new vaccine that could spell the end of polio has been produced using a genetically modified "drug factory" plant.
The leaves of the plant, a close relative of tobacco, contain virus-like particles that mimic the polio pathogen but are incapable of causing a harmful disease.
In animal tests, the viral particle vaccine tricked the immune system into setting up a defence against polio.
Researchers hope it will do the same for humans, without the risks associated with a weakened "live" vaccine that in rare cases triggers symptoms including paralysis.
Although a harmless de-activated polio vaccine exists it is five times more expensive than the live vaccine and difficult to administer.
A vaccine mass-produced in plants could provide a cost-effective solution that may eventually bring about the elimination of polio around the world, the scientists believe.
Project leader Professor Dave Rowlands, from the University of Leeds, said: "Small scale laboratory tests demonstrated that the ground-breaking synthetic vaccine provided animals with immunity from the disease similar to the existing widely used vaccine....
"The results of our research pave the way towards production of a novel synthetic vaccine to help bring about the global elimination of poliomyelitis. Such a vaccine would be quicker, easier and safer to produce, without the inherent danger of accidental release of virus associated with the production of current vaccines."
The research, reported in the journal Nature Communications, was funded by the World Health Organisation and the Bill & Melinda Gates Foundation. Both are actively searching for new vaccines that will aid the international drive to eradicate polio.
A team at the John Innes Centre in Norwich used soil bacteria to carry the genetic instructions for making the vaccine into the plants.
Other scientists from the Diamond Light Source synchrotron facility near Didcot, Oxfordshire, used an advanced form of electron microscopy to analyse the viral particles and confirm they had the same structure as the "real" polio virus.
Experiments were then conducted in mice to see how their immune systems responded to the vaccine.
Polio was a global scourge until the middle of the last century.
Since 1988 the Global Polio Eradication Initiative led by the WHO has reduced incidence of the disease by 99 per cent, but the disease has stubbornly resisted complete elimination.
A few hundred cases of infection still occur each year worldwide, and the numbers are remaining steady with the virus kept at large by use of the live vaccine.
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