Pharmaceutical Plants

Yesterday, the Proceedings of the National Academy of Sciences (PNAS) published a paper describing the use of tobacco plants to produce a vaccine against one of humankind’s longtime scourges, the plague. In the study, scientists genetically modified tobacco mosaic virus (TMV) with genes from Yersinia pestis, the bacteria that causes plague. They then infected tobacco plants with the virus, making the plants effective producers of plague vaccine, pumping out the plague bacterial proteins necessary to stimulate the immune system to provide protection against the disease. After guinea pigs were exposed to Yersinia pestis, all untreated animals died, but 38 to 75% of vaccinated animals survived, depending on the specific vaccine used.

Although this is an interesting development, this study uses transgenic virus, not transgenic plants. As I stated in my previous post entitled “Biotechnology for the Masses”, pharmaceutical production by transgenic crops has not been fully realized, although it is promising, and examples of this promise do exist in the scientific literature.

A paper published in March 2005 in PNAS described a clinical trial in which participants ate potatoes that acted as a hepatitis B vaccine, having been genetically modified to produce proteins from the hepatitis B virus. Although the scientists could obviously not infect the participants with the hepatitis B virus to test the effectiveness of the vaccine, they did measure their immune response to the vaccine and found that 53 to 63% of participants responded to the vaccine, depending on how many potatoes they ate. The use of edible vaccines is especially suited for health campaigns in the developing world, so additional research along these lines could have great humanitarian implications.