Potato Hepatitis B Vaccine Succeeds in Human Trial
Genetically Modified Potatoes Prevent Hepatitis B (Sansi Science Report)
American scientists have developed a genetically modified potato that may act as a hepatitis B vaccine, which is good news for developing countries.
The hepatitis B virus attacks the liver and claims about 500,000 lives each year. But traditional vaccines require refrigeration, which is difficult to achieve in remote areas of warm developing countries. Medical workers often must also struggle to determine whether the expensive hepatitis B vaccine has been rendered ineffective by accidental heat exposure during transport.
To this end, biologist Charles Arntzen of the University of Arizona and his colleagues designed a refrigeration-free, edible vaccine: the potato. They took a gene from the hepatitis B virus and inserted it into potato plants, which then produced the viral antigen. After a person eats this potato, the antigen protein triggers an immune response against the hepatitis B virus.
The research team says that although this method is unlikely to replace the initial immunization injection, it could replace the later booster injections that maintain immunity. Julian Ma, an immunologist at St George's Hospital Medical School in London, said: "It has the potential to have a major impact on global health."
Super Potato
In the trial conducted by Arntzen and his colleagues using this genetically modified potato, participants had received an initial hepatitis B vaccination between 1 and 15 years earlier. The results showed that 19 of the 33 participants produced more hepatitis B antibodies after eating the potato, and one of them saw antibody levels rise 56-fold. The report was published in the Proceedings of the National Academy of Sciences (PNAS).
The potato vaccine worked in 60% of the trial participants, which is good news. The researchers explained that even commercial vaccines containing special substances to attract immune cells and enhance the immune response do not reach a 10% effectiveness rate.
The Process of Progress
Arntzen's team has already combined two other vaccines into potatoes, one against traveler's diarrhea caused by E. coli and one against enteric flu caused by Norwalk factor.
"We are very pleased," Arntzen said. "There are always skeptics who say this can't be done, but we solved all these problems." Unlike E. coli and Norwalk factor, the hepatitis B virus has not evolved to survive in the intestine, so the success of this new vaccine is especially surprising: if the hepatitis B vaccine in the potato is to act on the immune system and take effect, it must first pass the test of the digestive tract.
However, raw potatoes are not a very appetizing food, and the vaccine content in them is not very stable. For this reason, Arntzen and his colleagues are focusing on genetically modified tomatoes containing the vaccine and trying to turn them into pills. He said: "Hopefully we will never again need to conduct human clinical trials with unprocessed material."