If it works, it could reduce the cost of storing and transporting vaccines by hundreds of millions of dollars every year.
PODGER: Getting vaccines to remote regions in poor countries can present a huge challenge. They often need refrigerating, and medical workers need to be on hand to give injections. The work by Hiroshi Kiyono and his team at Tokyo University does away with these challenges. They've found a way of genetically engineering a strain of rice which contains a vaccine against cholera. The rice can be ground up and made into a pill or capsule, which will keep at room temperature for up to two years, as Dr Kiyono explains.
KIYONO: We have tested up to two years under normal teperature condition, then tested for effectiveness. We were able to show that capsule containing fresh harvested rice vaccine powder kept under normal temperature for two years, would have the same effectiveness to induce immune response.
PODGER: As well as transport and storage issues, oral vaccines in particular face another challenge: once you've taken a pill, it has to make it intact through the powerful acids in the stomach -- and arrive in the intestines, where its beneficial qualities pass through the intestinal walls into the blood. Dr Kiyono says rice is especially good at this, making it a good candidate for vaccine delivery.
KIYONO: Rice has unique protein body which is like a natural particle, it can be protected from an acid environment, so therefore can reach to the small intestine. Once you've taken it, then we have shown that those rice-expressed vaccine antigen can be taken up by tissue, processed, then initiate immuno-rsponse or initiate to build protection.
PODGER: So far the vaccine has worked on mice, and will soon be tested on primates. Dr Kiyono says cholera is a worthy target for this kind of research; it's so rare in rich countries that little attention's going into making better vaccines to protect against it. If it's caught early, cholera can be treated with rehydration salts; but untreated, it's fatal in around 50 percent of patients. Dr Robert Zeigler, director of the Philippines-based International Rice Research Institute, has welcomed the new study:
ZEIGLER: You can treat diarrhoeal diseases with rehydration salts. However that means that the person already has the disease, and for those of us who have suffered those diseases, they are extraordinarily painful and unpleasant and debilitating. Having a vaccine that would prevent getting the disease in the first place would be, I would think, far more friendlier to the population.
PODGER: Now Dr Kiyono's team hope to use their GM technique to produce rice strains to protect against other diseases, like botulism and flu. Dr Zeigler says that although the initial cost of producing modified rice strains and churning them out in pill form would be high, the lower associated transport and administering costs would make it cheaper in the long run.
ZEIGLER: Even the initial upfront costs of genetically engineering rice to produce a cholera vaccine or a vaccine against influenza, while nominally high, on a per dose basis would be very very low. To be able to have a vaccine, transport it to the most regions, and have it administered at the convenience of the recipients is very attractive. Transporting salts and having to teach people how to mix them with water and how to administer them is more complex than just distributing orally-taken vaccines.