A spoonful of rice could soon vaccinate your child against cholera. Scientists from the University of Tokyo have developed a type of rice that carries the cholera vaccine, which will not need refrigeration or injections for delivery.

The edible rice vaccine for the deadly water-borne disease has successfully passed the test in mice. The team now plans to start primate trials of the rice. If proved successful, this breakthrough may come as a boon for India where rice is the staple food of 85% of the country's population and where cholera is a major problem.

According to Hiroshi Kiyono, the lead researcher, who announced the breakthrough in Tuesday's issue of 'Proceedings of the National Academy of Sciences', the rice vaccine provided a two-tier immunity in mice who consumed the transgenic rice and had several advantages over standard injectable cholera vaccines.

It does not need to be injected, purified or refrigerated and was found to be highly effective after being stored for a year-and-a-half at room temperature. It also did not dissolve in the stomach and lasted till it reached the intestine where it instigated the immune response against the cholera bacteria.

The Japan team created the vaccine by inserting part of the bacterium, vibrio cholerae, into the Kitaake rice plant. About 30 micrograms of the genes were introduced into each grain of rice. The transgenic rice was then fed to mice in the form of powder.

The new vaccine subsequently demonstrated a superior immunity level. It not only provoked normal resistance in the body but also produced antibodies in the nose, mouth and urinary tracts mucosal surfaces.

Director of the National Institute for Cholera and Enteric Diseases, Kolkata, S K Bhattacharya, told TOI, "For India, it has great promise because most of its population consumes rice and where refrigeration can be a problem in remote villages."

However, a slightly skeptical Bhattacharya added, "Scientists were trying to inject potatoes with this vaccine. But potatoes, like rice, need to be boiled for consumption. The vaccine when boiled might become ineffective."

The use of cholera vaccine was scrapped in 1970s in India because it was found to be only 30%-50% effective and provided immunity only for eight months. Bhattacharya is now trying to recreate the whole-cell heat killed oral vaccine. Imported from Vietnam and modified for use in India, the stronger vaccine will be effective against both the O1 and O139 types of cholera that are common in India.

The vaccine has already been tried on 110,000 people in Kolkata. Reacting to the study, HOD of genetics at the Indian Agricultural Research Institute K V Prabhu said attempts to alter plants to produce proteins that induce an immune reaction to various diseases have been underway for years but none has reached the state where it could be used in humans.