NEW YORK (Reuters Health) - In a new study, Japanese researchers describe the development of an experimental rice-based oral vaccine that requires neither refrigeration nor injection.
Because of these properties, mucosal vaccines, which are absorbed through the mucosal tissues, rather than injected, are considered ideal for combating infectious diseases on a global scale. In the present study, Dr. Hiroshi Kiyono, from the University of Tokyo, and colleagues describe the creation of a rice-based mucosal vaccine against cholera, which was used in a series of animal studies.
The vaccine was designed to express a subunit of the disease-causing cholera toxin B, according to the report in the Early Edition of the Proceedings of the National Academy of Sciences. About 30 micrograms of the subunit were stored in each rice seed.
After feeding the vaccine to mice, the researchers noted that the cholera toxin B antigen expressed by rice seeds was absorbed. This caused the immune system to release very specific antibodies that were capable of neutralizing the cholera toxin.
The rice-based vaccine was also resistant to digestion by gastric juices in the stomach and remained active even after long-term storage at room temperature.
"Rice-based mucosal vaccines offer a highly practical and cost-effective strategy for orally vaccinating large populations against mucosal infections, including those that may result from an act of bioterrorism," the authors conclude.
SOURCE: Proceedings of the National Academy of Sciences, early addition, June 11, 2007.
