Korean researchers have taken a promising first step towards finding an edible vaccine against the neurodegenerative disease – and to do so they have turned to the humble tomato.
HyunSoon Kim from the Korea Research Institute of Bioscience and Biotechnology say that the tomato could be a suitable carrier for an oral vaccine against Alzheimer’s disease.
“Tomatoes are an attractive candidate as a vaccine carrier because they can be eaten without heat treatment, which reduces the risk of destroying the immune stimulation potential of the foreign protein,” said Kim.
Alzheimer’s is thought to be caused by the accumulation of human beta-amyloid, a toxic insoluble fibrous protein in the brain, which leads to the death of neurons. Reducing the accumulation of beta-amyloid may inhibit the degeneration of the nervous system and therefore prevent or delay the onset of Alzheimer’s disease. One approach is to stimulate the immune system to reduce beta-amyloid in the brain.
Kim’s aim was to develop a plant-derived vaccine against Alzheimer’s disease, since beta-amyloid is toxic to animal cells. The researchers inserted the beta-amyloid gene into the tomato genome and measured the immune responses to the tomato-derived toxic protein in a group of 15-month-old mice.
They immunised the mice orally with the transgenic tomato plants once a week for three weeks, and also gave the mice a booster seven weeks after the first tomato feed. Blood analyses showed a strong immune response after the booster, with the production of antibodies to the human foreign protein.
Kim said: “Although we did not reveal a reduction of existing plaques in the brain of mice challenged with tomato-derived beta-amyloid, this study represents a unique approach in which transgenic plants expressing beta-amyloid protein are used to produce a vaccine.”
The team is currently looking at strategies to increase the potency of the tomato-based vaccine, because fresh tomatoes contain only 0.7% protein and levels of foreign protein are even lower. Their work is published online in the journal Biotechnology Letters.