Cholera vaccine from rice

17 June 2007
Posted by Chris Smith.

This week we have promising news for the fight against the dreadful disease cholera, because a team of scientists in Japan are developing a new vaccine against the disease using their national staple food - rice.

Cholera continues to be a huge problem across the developing world, with at least 5000 people a year, and probably a lot more, dying from the severe dehydration caused by chronic diarrhoea that is unleashed by eating food or water contaminated with Vibrio cholerae bacteria.  Fortunately it's a disease that's easily treated with clean fluids and antibiotics but sadly there are still millions of people in the world who don't have access to such treatment.

Now, researchers from the University of Tokyo have genetically engineered two strains of domestic rice to contain the CTB gene, which is a major protein of cholera bacteria.  The idea is that by introducing these cholera proteins into the body it will trigger an immune response that protects against future attacks of the disease.The scientists have rather nicely called their new rice Mucorice, because cholera is a disease of the mucosal lining of the intestine, and they've shown it to be effective in preventing cholera in mice.Sadly the vaccine can't be taken simply by eating a bowl of steamed rice, because that could give the wrong dosage, but it can easily be made into tablets that are swallowed, getting rid of the need to inject vaccines with needles which can cause other problems like secondary infections and disposal.  Another good thing about these tablets is that they don't need to be stored in refrigerators and the rice can easily be grown in areas of the developing world where cholera is still a huge problem.One of the really important breakthroughs with this technique is that the researchers have found a way of delivering the vaccine to the intestine - just where it's needed - without being broken down in the harsh enzyme-laden environment of the stomach.  Rice grains survive digestion in the stomach, and even when ground up into tablets the CTB protein is stable enough to pass through the stomach unharmed. So it's hoped that this new technique could be used to develop vaccines for other diseases of the intestine like flu, botulism and maybe even anthrax.

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