Why vaccination by potato got chopped
New Scientist 19 February 2005
ONE of the first human trials of an edible vaccine produced promising results. But the vaccine, a potato genetically engineered to produce a hepatitis B protein, has been abandoned because of fears that "pharm" crops could be mixed up with normal produce.
Details of the potato's trial have only just been published in Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0409899102). When 42 volunteers ate two or three doses of the raw potato, concentrations of hepatitis B antibodies in their blood increased up to 60-fold.
The idea of edible vaccines like this was to enable developing countries to produce cheap vaccines that could be stored without refrigerators. But enthusiasm has cooled because of fears that vaccine-laden fruit and veg might be confused with normal produce, with potentially dangerous consequences.
So the team that developed the vaccine axed the project two years ago. Instead, it is switching to producing vaccines in non-food plants such as Nicotiana benthamiana, a relative of tobacco. The idea is to immunise people by giving them pills containing the preserved, ground-up leaves of the plants.
"We don't say 'edible' any more," says team leader Charles Arntzen of Arizona State University, one of the pioneers in the field. "We say, 'heat-stable oral vaccines' now." From issue 2487 of New Scientist magazine, 19 February 2005, page 19