- A genetically modified potato containing a vaccine for
hepatitis B has been successfully tested on animals, scientists reported
- 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
- 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
- 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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