"Protective antigen (PA) of Bacillus anthracis is one of the three components of the anthrax toxin," says Alexander Karasev, a lead researcher on the study. "Purified PA is currently used as a vaccine against anthrax. However, the licensed vaccine derived from apathogenic B. anthracis has side effects and a more efficacious and safer vaccine is needed."
Karasev and his colleagues have genetically engineered a tobacco mosaic virus that, when inserted into spinach plants, instructs the plants to manufacture fragments of PA. The fragments can then easily be purified and used in a vaccine. They are already being used in the production of PA specific antibodies in laboratory animals.
"Plants can be an excellent vehicle for production of a subunit vaccine against anthrax based on protective antigen," says Karasev.