GM Potato Vaccine Found
For Hepatitis B
By Mark Henderson - Science Correspondent,,27195,00.html
A genetically modified potato containing a vaccine for hepatitis B has been successfully tested on animals, scientists reported yesterday.
The breakthrough by researchers at Cornell University in New York raises the prospect of cheap and effective oral vaccines in fruit and vegetables, which could revolutionise healthcare in the Third World.
In a study reported in Nature Biotechnology, scientists modified potatoes with a gene for HBsAg, an antigen found on the surface of the hepatitis B virus that stimulates the body to produce antibodies but does not cause infection. HBsAg is the basis of existing vaccines for the disease, administered by injection.
Mice fed three times a week with the GM potatoes began to produce antibodies to hepatitis B, which would protect them from infection with the virus, the study found.
The experiment is the first to prove that an oral vaccine gives rise to antibodies in the blood to a disease that is not transmitted orally. The only such vaccine presently available is for polio, which infects its victims orally. Hepatitis is transmitted by sexual or blood contact.
More than two billion people - about a third of the world's population - have been infected with hepatitis B. Of these, up to 500 million are chronic carriers, who are at risk of developing the acute form of the disease.
Symptoms of the virus include poor appetite, nausea, vomiting, headaches, general malaise and jaundice. Its effects can include long-term liver damage and liver cancer.
An injectable vaccine developed in 1978 has largely limited the spread of the disease in the developed world. The traditional vaccine, however, must be kept refrigerated and at £10 a dose is often too expensive to be used in the Third World.

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