1th quarter 2005

Potatoes against hepatitis

Edible vaccine works in humans

Over 100 million people worldwide carry the hepatitis B virus, which causes cirrhosis and cancer of the liver and is responsible for about one million deaths per year. An effective vaccine has been available since the 1980s. Because it is expensive, however, even in the USA there are still about 300,000 new hepatitis B infections every year. Moreover, the vaccine has to be kept refrigerated at all times. This is why it cannot be used in many developing countries.

For the above reasons, scientists are now looking for ways to produce non-perishable vaccines locally and at low cost with the help of edible plants.

A first remarkable study result has now been published. A team of US scientists reported that a potato into which they had incorporated a gene encoding a part of the hepatitis B virus (the same HBs antigen which is used in the conventional vaccine) triggered an immune response in humans. To get vaccinated, it is sufficient to eat a few hundred grams of raw, genetically modified potatoes; raw because cooking would destroy the vaccine. The vaccine was tested on 33 healthy volunteers who had already been vaccinated with the conventional serum and had low blood antibody levels. 19 test persons showed increased antibody production after ingesting the potatoes, which is the desired effect of a vaccination.

Nevertheless, many hurdles will have to be overcome before the method is ready for use. Using genetically modified plants for vaccine production is a promising concept in the battle against infectious diseases. There are few other options, especially for poor countries, which are hardest hit by the disease. In the short term, further studies on small groups of human subjects can therefore be expected. In the medium term, large-scale studies need to be conducted under realistic conditions.

Critics have already pointed to the risk that the vaccine may be mistaken for normal food. In fact, molecular biological methods (genetic tests, antibody tests) are needed to tell apart a vaccine potato from a normal one. For this reason, researchers also consider using plants for vaccine production which are not part of the normal human diet.

The recent study has confirmed that vaccination by means of edible plants is a viable option. The low response rate (19 out of 33) is no argument against this, because there are some possible ways of increasing effectiveness that have not yet been applied.

9 March 2005