Scientists in the United States have developed a potential vaccine against hepatitis B by genetically modifying potato plants.
The modified plants produce one of the hepatitis virus's proteins, which might be enough to boost the immune systems of people eating the potatoes and protect them from infection.
The researchers at the Roswell Park Cancer Institute in Buffalo, New York, found signs of immunity in 60 per cent of the 42 people they tested it on.
Hepatitis B severely affects the liver and kills one million people each year. Many of these are in developing countries, where buying and storing the existing vaccine can be prohibitively expensive. The simplicity and low cost of an edible vaccine would make it ideal for global immunisation programmes.
The prototype needs more testing, and there are questions over whether the recently tested vaccine boosted people's immune system strongly enough. But Yasmin Thanavala and colleagues, whose results are published this week in Proceedings of the National Academy of Sciences of the United States of America, are confident it will lead to an oral hepatitis B vaccine that could be given as a capsule or powder.