Antibodies from tobacco plants protect against anthrax

Scientists have produced, in tobacco plants, human antibodies that could be used to treat anthrax exposure. They reported their findings at the 2005 American Society for Microbiology Biodefense Research Meeting.

"The nature of bioterrorism is such that an aggressor is likely to strike at a time and place calculated to induce maximum terror through mass casualties. The unpredictable nature of such events compels us to develop cost-effective, highly stable medical countermeasures to enable authorities to treat individuals exposed to bioterror agents such as anthrax," says Les Baillie of the Naval Medical Research Center. Dr. Baillie, who is also associated with the University of Maryland Biotechnology Institute, conducted his research in collaboration with Dr. Vidadi Yusibov, Director of the Fraunhofer USA Center for Molecular Biotechnology (CMB) in Newark, Delaware. Funding for this project at the Fraunhofer USA CMB was obtained through the efforts of a congressional delegation lead by Delaware's Senior Senator Joe Biden.

To create the "plantibodies," Baillie and his colleagues first collected the cells that make antibodies from individuals who had been vaccinated against anthrax. Then genes that encode the antibody itself were inserted into a bacterium that transfers the gene into the plant cells. "The plant makes the antibody for you in a few days," says Baillie.

The antibodies were then purified from leaves harvested from the infected plants and tested for their ability to protect mice against anthrax infection. The plant-produced antibodies were just as effective as the antibodies produced by human cells from immunized individuals.

The antibodies can be used either before exposure to prevent infection or after exposure as treatment.

"If you've been exposed to an agent, you want protection as soon as possible. Vaccination can take a very long time to build immunity. Antibodies give you immediate protection," says Baillie.

"Plant-produced antibodies are also safer because there is no risk of contamination by human or animal pathogens, and plant viruses are not known to infect humans," says Yusibov.

"It is an easy, inexpensive and, very stable system. If you're looking for a way to stockpile a large amount of antibodies for a long periods of time, plant-produced antibodies are the answer," says Baillie.

Anthrax antibodies are just the first step for Baillie and his collaborators. Plantibodies against the plague bacterium and botulism are also in development.