Scientists may soon be able to grow vaccines in fruit and vegetables.
A British biotechnology company, Axis Genetics, has agreed on a collaboration with Cornell University where researchers have genetically engineered plants to make edible vaccines.Some have already been used to protect animals against disease, and clinical trials have begun on humans. In a few years, Axis expects to grow potatoes that will protect against diarrhea, bananas that will inoculate against hepatitis B and tomatoes that could save humans from rabies.
"Instead of having to keep vaccines refrigerated, as we do now, we will simply give them as pieces of dried banana or as tomato juice," said Dr. Iain Cubitt, chief executive of Axis. "A single field will be able to grow enough modified plants to provide vaccines for millions of people."
Plant vaccines are created by isolating a gene that directs the manufacture of a surface protein of a virus, such as hepatitis B. This gene is then inserted into a seed's genetic machinery. As it grows into a plant, it starts to manufacture the virus protein. When the plant is eaten, the protein stimulates defenses against the virus from which it was first isolated.
Scientists believe edible vaccines will protect humans by stimulating the body's first line of defenses, the mucosal linings of the gut, nose and mouth. Standard vaccines - which are injected - stimulate secondary defenses in the blood.
Last month scientists at the Boyce Thomson Institute at Cornell reported in Nature Medicine that they had completed the first clinical trial of an edible vaccine for humans. Volunteers ate golf ball-size pieces of raw potato, genetically engineered to make pieces of the protein coat of the virus that causes diarrhea. Tests showed these individuals produced defense antibodies to the virus.
Now Axis, which is based in Cambridge, England, and which pioneered research on animal vaccines made in plants, has struck an exclusive deal with Cornell. In exchange for Axis stock and a fee of $6 million, institute researchers will provide expertise and data.
"We are not going to create vaccines that can be plucked off a tree," Cubitt said. "Instead we will use standard food processing technology to treat vaccine plants and create dried products, pastes or pills."