Growing Rice and a Cholera Vaccine at the
Same Time
Researchers experiment with a plant-based way to protect
against the intestinal infection and possibly other diseases. Transcript of
radio broadcast:
25 June 2007
This is the VOA Special English Agriculture
Report.
Someday, rice plants might not only provide food
but also a way to prevent cholera and other diseases.
Cholera is a bacterial infection of the
intestines. Today it is found mostly in Africa, Asia and Latin America. Current
vaccines to protect against cholera must be kept in cold storage. The need for
refrigeration limits use in poor countries.
But research in Japan may lead to rice plants
that contain a cholera vaccine that does not need to be kept cold. So far, the
research has been carried out only on mice. The Proceedings of the National
Academy of Sciences in the United States published the study earlier this
month.
Hiroshi Kiyono of the University of Tokyo and his
team experimented with genetic material from the bacterium responsible for
cholera. They placed it into the Kitaake rice plant.
Mice ate the genetically changed rice seeds as a
powder. The report says the vaccine was not destroyed by stomach acid; instead,
the animals developed antibodies against the cholera toxin. The scientists say
the vaccine remained active even after being stored at room temperature for more
than a year and a half.
People would take the vaccine as a drug that
contains the powder.
Cholera is usually spread through water or food,
in places where conditions are dirty and drinking water supplies are unsafe.
Cholera infections are often mild. But some people develop severe cases. The
World Health Organization says half of them will die if they are not
treated.
The researchers say the experimental cholera
vaccine produced reactions in the immune system and in areas of mucosal tissue.
Mucosal surfaces include the mouth, nose and reproductive organs. Cholera as
well as viruses like those that cause influenza and AIDS infect these areas.
The scientists have great hopes for rice-based
vaccines as a way to protect large populations against mucosal infections. There
would be no need for injection, since the vaccine would be taken by
mouth.
Yet scientists have tried for some time to make
plant-based vaccines. Researchers in the United States have developed one for
Newcastle disease in chickens, but so far there are no products for humans. At
the same time, scientists have to deal with concerns about genetically
engineered plants accidentally mixing with food crops.
And that's the VOA Special English Agriculture
Report, written by Jerilyn Watson.