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October 2000
Vol. 3, No. 8, p. 21.

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Do you want vaccine with that?

...Imagine a world where you could be immunized against viral infection by eating. This is one step closer to reality with the development and clinical trials of the first antiviral vaccine to be delivered in a potato.

Research has demonstrated that the capsid protein of the Norwalk virus, a major cause of acute epidemic gastroenteritis, assembles into stable viruslike particles that can be safely ingested to generate an immune response. Using this fact, researchers at several institutes performed clinical tests of a potato that was genetically engineered to produce these noninfectious capsid particles (J. Inf. Dis. 2000, 182, 302–305).

According to Genevieve Losonsky, a researcher at Baltimore’s Center for Vaccine Development, foodborne vaccines can solve several oral vaccine delivery problems at once by protecting the antigen from the harsh environment of the digestive tract and by simplifying worldwide production. She explains, “Because most pathogens enter the host at mucosal surfaces, delivery of vaccines to the gastrointestinal tract offers one of the best routes for immunization.”

Initial experiments established that the edible vaccine induced an immune response in mice. Similarly, when the potato vaccine or placebo was given to 24 human volunteers in a double-blind trial, the vaccinated humans also generated specific immune responses, as measured by the levels of various immunoglobulins and immunoglobulin-secreting cells in blood and stool samples. It is hoped that future work will demonstrate the vaccine’s ability to protect against Norwalk virus infection.

But Losonsky cautions that several challenges remain. For such edible vaccines to be effective, the dose of antigen produced will need to be controlled and a more palatable delivery system will need to be developed.


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