Plants have been “hijacked” to make polio vaccine in a breakthrough with the potential to transform vaccine manufacture, say scientists. The team at the John Innes Centre, in Norfolk, says the process is cheap, easy and quick. As well as helping eliminate polio, the scientists believe their approach could help the world react to unexpected threats such as Zika virus or Ebola. Experts said the achievement was both impressive and important. The vaccine is an “authentic mimic” of poliovirus called a virus-like particle. Outwardly it looks almost identical to poliovirus but – like the difference between a mannequin and person – it is empty on the inside. It has all the features needed to train the immune system, but none of the weapons to cause an infection. The scientists hijacked a relative of the tobacco plant’s metabolism to turn its leaves into polio-vaccine “factories”. First, they needed to create new instructions for the plant to follow. The starting material was the genetic code for making the outer surface of poliovirus. It was enhanced by combining it with material from viruses that naturally infect plants. The new instructions were then put into soil bacteria, which were used to infect tobacco. The infection took hold; the plants read the genetic instructions and started making the virus-like particles. Infected leaves were mixed with water, blended, and the polio vaccine was extracted. The virus-like particles prevented polio in animal experiments, and an analysis of their 3D structure showed they looked almost identical to poliovirus. Prof George Lomonossoff, from the John Innes Centre, told the BBC News website: “They are incredibly good mimics. “It’s a very promising technology, “I would hope we get vaccines produced in plants in the not too distant future.” The research is funded by the World Health Organization, as part of efforts to find replacements for the polio vaccine. Polio – which can cause permanent paralysis – is a thing of the past for most of the world, but the infection has not been eradicated. And using weakened poliovirus in current vaccines poses a risk of the virus regaining some of its dangerous traits – called vaccine-derived poliovirus. Dr Andrew Macadam, principal scientist at the UK’s National Institute for Biological Standards and Control, said: “Current vaccines for polio are produced from large amounts of live virus, which carries a threat of accidental escape and re-introduction.
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